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swiftshader/SwiftShader/b8f1a3a/./third_party/llvm-10.0/llvm/lib/Transforms/IPO/Attributor.cpp
blob: f2995817eaf89606e5e25ec1d0a1c3aff19ce8ec [file]
//===- Attributor.cpp - Module-wide attribute deduction -------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements an inter procedural pass that deduces and/or propagating
// attributes. This is done in an abstract interpretation style fixpoint
// iteration. See the Attributor.h file comment and the class descriptions in
// that file for more information.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO/Attributor.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Verifier.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
using namespace llvm;
#define DEBUG_TYPE "attributor"
STATISTIC(NumFnWithExactDefinition,
"Number of function with exact definitions");
STATISTIC(NumFnWithoutExactDefinition,
"Number of function without exact definitions");
STATISTIC(NumAttributesTimedOut,
"Number of abstract attributes timed out before fixpoint");
STATISTIC(NumAttributesValidFixpoint,
"Number of abstract attributes in a valid fixpoint state");
STATISTIC(NumAttributesManifested,
"Number of abstract attributes manifested in IR");
STATISTIC(NumAttributesFixedDueToRequiredDependences,
"Number of abstract attributes fixed due to required dependences");
// Some helper macros to deal with statistics tracking.
//
// Usage:
// For simple IR attribute tracking overload trackStatistics in the abstract
// attribute and choose the right STATS_DECLTRACK_********* macro,
// e.g.,:
// void trackStatistics() const override {
// STATS_DECLTRACK_ARG_ATTR(returned)
// }
// If there is a single "increment" side one can use the macro
// STATS_DECLTRACK with a custom message. If there are multiple increment
// sides, STATS_DECL and STATS_TRACK can also be used separatly.
//
#define BUILD_STAT_MSG_IR_ATTR(TYPE, NAME) \
("Number of " #TYPE " marked '" #NAME "'")
#define BUILD_STAT_NAME(NAME, TYPE) NumIR##TYPE##_##NAME
#define STATS_DECL_(NAME, MSG) STATISTIC(NAME, MSG);
#define STATS_DECL(NAME, TYPE, MSG) \
STATS_DECL_(BUILD_STAT_NAME(NAME, TYPE), MSG);
#define STATS_TRACK(NAME, TYPE) ++(BUILD_STAT_NAME(NAME, TYPE));
#define STATS_DECLTRACK(NAME, TYPE, MSG) \
{ \
STATS_DECL(NAME, TYPE, MSG) \
STATS_TRACK(NAME, TYPE) \
}
#define STATS_DECLTRACK_ARG_ATTR(NAME) \
STATS_DECLTRACK(NAME, Arguments, BUILD_STAT_MSG_IR_ATTR(arguments, NAME))
#define STATS_DECLTRACK_CSARG_ATTR(NAME) \
STATS_DECLTRACK(NAME, CSArguments, \
BUILD_STAT_MSG_IR_ATTR(call site arguments, NAME))
#define STATS_DECLTRACK_FN_ATTR(NAME) \
STATS_DECLTRACK(NAME, Function, BUILD_STAT_MSG_IR_ATTR(functions, NAME))
#define STATS_DECLTRACK_CS_ATTR(NAME) \
STATS_DECLTRACK(NAME, CS, BUILD_STAT_MSG_IR_ATTR(call site, NAME))
#define STATS_DECLTRACK_FNRET_ATTR(NAME) \
STATS_DECLTRACK(NAME, FunctionReturn, \
BUILD_STAT_MSG_IR_ATTR(function returns, NAME))
#define STATS_DECLTRACK_CSRET_ATTR(NAME) \
STATS_DECLTRACK(NAME, CSReturn, \
BUILD_STAT_MSG_IR_ATTR(call site returns, NAME))
#define STATS_DECLTRACK_FLOATING_ATTR(NAME) \
STATS_DECLTRACK(NAME, Floating, \
("Number of floating values known to be '" #NAME "'"))
// Specialization of the operator<< for abstract attributes subclasses. This
// disambiguates situations where multiple operators are applicable.
namespace llvm {
#define PIPE_OPERATOR(CLASS) \
raw_ostream &operator<<(raw_ostream &OS, const CLASS &AA) { \
return OS << static_cast<const AbstractAttribute &>(AA); \
}
PIPE_OPERATOR(AAIsDead)
PIPE_OPERATOR(AANoUnwind)
PIPE_OPERATOR(AANoSync)
PIPE_OPERATOR(AANoRecurse)
PIPE_OPERATOR(AAWillReturn)
PIPE_OPERATOR(AANoReturn)
PIPE_OPERATOR(AAReturnedValues)
PIPE_OPERATOR(AANonNull)
PIPE_OPERATOR(AANoAlias)
PIPE_OPERATOR(AADereferenceable)
PIPE_OPERATOR(AAAlign)
PIPE_OPERATOR(AANoCapture)
PIPE_OPERATOR(AAValueSimplify)
PIPE_OPERATOR(AANoFree)
PIPE_OPERATOR(AAHeapToStack)
PIPE_OPERATOR(AAReachability)
PIPE_OPERATOR(AAMemoryBehavior)
PIPE_OPERATOR(AAValueConstantRange)
#undef PIPE_OPERATOR
} // namespace llvm
// TODO: Determine a good default value.
//
// In the LLVM-TS and SPEC2006, 32 seems to not induce compile time overheads
// (when run with the first 5 abstract attributes). The results also indicate
// that we never reach 32 iterations but always find a fixpoint sooner.
//
// This will become more evolved once we perform two interleaved fixpoint
// iterations: bottom-up and top-down.
static cl::opt<unsigned>
MaxFixpointIterations("attributor-max-iterations", cl::Hidden,
cl::desc("Maximal number of fixpoint iterations."),
cl::init(32));
static cl::opt<bool> VerifyMaxFixpointIterations(
"attributor-max-iterations-verify", cl::Hidden,
cl::desc("Verify that max-iterations is a tight bound for a fixpoint"),
cl::init(false));
static cl::opt<bool> DisableAttributor(
"attributor-disable", cl::Hidden,
cl::desc("Disable the attributor inter-procedural deduction pass."),
cl::init(true));
static cl::opt<bool> AnnotateDeclarationCallSites(
"attributor-annotate-decl-cs", cl::Hidden,
cl::desc("Annotate call sites of function declarations."), cl::init(false));
static cl::opt<bool> ManifestInternal(
"attributor-manifest-internal", cl::Hidden,
cl::desc("Manifest Attributor internal string attributes."),
cl::init(false));
static cl::opt<unsigned> DepRecInterval(
"attributor-dependence-recompute-interval", cl::Hidden,
cl::desc("Number of iterations until dependences are recomputed."),
cl::init(4));
static cl::opt<bool> EnableHeapToStack("enable-heap-to-stack-conversion",
cl::init(true), cl::Hidden);
static cl::opt<int> MaxHeapToStackSize("max-heap-to-stack-size", cl::init(128),
cl::Hidden);
/// Logic operators for the change status enum class.
///
///{
ChangeStatus llvm::operator|(ChangeStatus l, ChangeStatus r) {
return l == ChangeStatus::CHANGED ? l : r;
}
ChangeStatus llvm::operator&(ChangeStatus l, ChangeStatus r) {
return l == ChangeStatus::UNCHANGED ? l : r;
}
///}
Argument *IRPosition::getAssociatedArgument() const {
if (getPositionKind() == IRP_ARGUMENT)
return cast<Argument>(&getAnchorValue());
// Not an Argument and no argument number means this is not a call site
// argument, thus we cannot find a callback argument to return.
int ArgNo = getArgNo();
if (ArgNo < 0)
return nullptr;
// Use abstract call sites to make the connection between the call site
// values and the ones in callbacks. If a callback was found that makes use
// of the underlying call site operand, we want the corresponding callback
// callee argument and not the direct callee argument.
Optional<Argument *> CBCandidateArg;
SmallVector<const Use *, 4> CBUses;
ImmutableCallSite ICS(&getAnchorValue());
AbstractCallSite::getCallbackUses(ICS, CBUses);
for (const Use *U : CBUses) {
AbstractCallSite ACS(U);
assert(ACS && ACS.isCallbackCall());
if (!ACS.getCalledFunction())
continue;
for (unsigned u = 0, e = ACS.getNumArgOperands(); u < e; u++) {
// Test if the underlying call site operand is argument number u of the
// callback callee.
if (ACS.getCallArgOperandNo(u) != ArgNo)
continue;
assert(ACS.getCalledFunction()->arg_size() > u &&
"ACS mapped into var-args arguments!");
if (CBCandidateArg.hasValue()) {
CBCandidateArg = nullptr;
break;
}
CBCandidateArg = ACS.getCalledFunction()->getArg(u);
}
}
// If we found a unique callback candidate argument, return it.
if (CBCandidateArg.hasValue() && CBCandidateArg.getValue())
return CBCandidateArg.getValue();
// If no callbacks were found, or none used the underlying call site operand
// exclusively, use the direct callee argument if available.
const Function *Callee = ICS.getCalledFunction();
if (Callee && Callee->arg_size() > unsigned(ArgNo))
return Callee->getArg(ArgNo);
return nullptr;
}
/// For calls (and invokes) we will only replace instruction uses to not disturb
/// the old style call graph.
/// TODO: Remove this once we get rid of the old PM.
static void replaceAllInstructionUsesWith(Value &Old, Value &New) {
if (!isa<CallBase>(Old))
return Old.replaceAllUsesWith(&New);
SmallVector<Use *, 8> Uses;
for (Use &U : Old.uses())
if (isa<Instruction>(U.getUser()))
Uses.push_back(&U);
for (Use *U : Uses)
U->set(&New);
}
/// Recursively visit all values that might become \p IRP at some point. This
/// will be done by looking through cast instructions, selects, phis, and calls
/// with the "returned" attribute. Once we cannot look through the value any
/// further, the callback \p VisitValueCB is invoked and passed the current
/// value, the \p State, and a flag to indicate if we stripped anything. To
/// limit how much effort is invested, we will never visit more values than
/// specified by \p MaxValues.
template <typename AAType, typename StateTy>
static bool genericValueTraversal(
Attributor &A, IRPosition IRP, const AAType &QueryingAA, StateTy &State,
const function_ref<bool(Value &, StateTy &, bool)> &VisitValueCB,
int MaxValues = 8) {
const AAIsDead *LivenessAA = nullptr;
if (IRP.getAnchorScope())
LivenessAA = &A.getAAFor<AAIsDead>(
QueryingAA, IRPosition::function(*IRP.getAnchorScope()),
/* TrackDependence */ false);
bool AnyDead = false;
// TODO: Use Positions here to allow context sensitivity in VisitValueCB
SmallPtrSet<Value *, 16> Visited;
SmallVector<Value *, 16> Worklist;
Worklist.push_back(&IRP.getAssociatedValue());
int Iteration = 0;
do {
Value *V = Worklist.pop_back_val();
// Check if we should process the current value. To prevent endless
// recursion keep a record of the values we followed!
if (!Visited.insert(V).second)
continue;
// Make sure we limit the compile time for complex expressions.
if (Iteration++ >= MaxValues)
return false;
// Explicitly look through calls with a "returned" attribute if we do
// not have a pointer as stripPointerCasts only works on them.
Value *NewV = nullptr;
if (V->getType()->isPointerTy()) {
NewV = V->stripPointerCasts();
} else {
CallSite CS(V);
if (CS && CS.getCalledFunction()) {
for (Argument &Arg : CS.getCalledFunction()->args())
if (Arg.hasReturnedAttr()) {
NewV = CS.getArgOperand(Arg.getArgNo());
break;
}
}
}
if (NewV && NewV != V) {
Worklist.push_back(NewV);
continue;
}
// Look through select instructions, visit both potential values.
if (auto *SI = dyn_cast<SelectInst>(V)) {
Worklist.push_back(SI->getTrueValue());
Worklist.push_back(SI->getFalseValue());
continue;
}
// Look through phi nodes, visit all live operands.
if (auto *PHI = dyn_cast<PHINode>(V)) {
assert(LivenessAA &&
"Expected liveness in the presence of instructions!");
for (unsigned u = 0, e = PHI->getNumIncomingValues(); u < e; u++) {
const BasicBlock *IncomingBB = PHI->getIncomingBlock(u);
if (LivenessAA->isAssumedDead(IncomingBB->getTerminator())) {
AnyDead = true;
continue;
}
Worklist.push_back(PHI->getIncomingValue(u));
}
continue;
}
// Once a leaf is reached we inform the user through the callback.
if (!VisitValueCB(*V, State, Iteration > 1))
return false;
} while (!Worklist.empty());
// If we actually used liveness information so we have to record a dependence.
if (AnyDead)
A.recordDependence(*LivenessAA, QueryingAA, DepClassTy::OPTIONAL);
// All values have been visited.
return true;
}
/// Return true if \p New is equal or worse than \p Old.
static bool isEqualOrWorse(const Attribute &New, const Attribute &Old) {
if (!Old.isIntAttribute())
return true;
return Old.getValueAsInt() >= New.getValueAsInt();
}
/// Return true if the information provided by \p Attr was added to the
/// attribute list \p Attrs. This is only the case if it was not already present
/// in \p Attrs at the position describe by \p PK and \p AttrIdx.
static bool addIfNotExistent(LLVMContext &Ctx, const Attribute &Attr,
AttributeList &Attrs, int AttrIdx) {
if (Attr.isEnumAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isStringAttribute()) {
StringRef Kind = Attr.getKindAsString();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
if (Attr.isIntAttribute()) {
Attribute::AttrKind Kind = Attr.getKindAsEnum();
if (Attrs.hasAttribute(AttrIdx, Kind))
if (isEqualOrWorse(Attr, Attrs.getAttribute(AttrIdx, Kind)))
return false;
Attrs = Attrs.removeAttribute(Ctx, AttrIdx, Kind);
Attrs = Attrs.addAttribute(Ctx, AttrIdx, Attr);
return true;
}
llvm_unreachable("Expected enum or string attribute!");
}
static const Value *
getBasePointerOfAccessPointerOperand(const Instruction *I, int64_t &BytesOffset,
const DataLayout &DL,
bool AllowNonInbounds = false) {
const Value *Ptr =
Attributor::getPointerOperand(I, /* AllowVolatile */ false);
if (!Ptr)
return nullptr;
return GetPointerBaseWithConstantOffset(Ptr, BytesOffset, DL,
AllowNonInbounds);
}
ChangeStatus AbstractAttribute::update(Attributor &A) {
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
if (getState().isAtFixpoint())
return HasChanged;
LLVM_DEBUG(dbgs() << "[Attributor] Update: " << *this << "\n");
HasChanged = updateImpl(A);
LLVM_DEBUG(dbgs() << "[Attributor] Update " << HasChanged << " " << *this
<< "\n");
return HasChanged;
}
ChangeStatus
IRAttributeManifest::manifestAttrs(Attributor &A, const IRPosition &IRP,
const ArrayRef<Attribute> &DeducedAttrs) {
Function *ScopeFn = IRP.getAssociatedFunction();
IRPosition::Kind PK = IRP.getPositionKind();
// In the following some generic code that will manifest attributes in
// DeducedAttrs if they improve the current IR. Due to the different
// annotation positions we use the underlying AttributeList interface.
AttributeList Attrs;
switch (PK) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
return ChangeStatus::UNCHANGED;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
Attrs = ScopeFn->getAttributes();
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
Attrs = ImmutableCallSite(&IRP.getAnchorValue()).getAttributes();
break;
}
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
LLVMContext &Ctx = IRP.getAnchorValue().getContext();
for (const Attribute &Attr : DeducedAttrs) {
if (!addIfNotExistent(Ctx, Attr, Attrs, IRP.getAttrIdx()))
continue;
HasChanged = ChangeStatus::CHANGED;
}
if (HasChanged == ChangeStatus::UNCHANGED)
return HasChanged;
switch (PK) {
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_FUNCTION:
case IRPosition::IRP_RETURNED:
ScopeFn->setAttributes(Attrs);
break;
case IRPosition::IRP_CALL_SITE:
case IRPosition::IRP_CALL_SITE_RETURNED:
case IRPosition::IRP_CALL_SITE_ARGUMENT:
CallSite(&IRP.getAnchorValue()).setAttributes(Attrs);
break;
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
break;
}
return HasChanged;
}
const IRPosition IRPosition::EmptyKey(255);
const IRPosition IRPosition::TombstoneKey(256);
SubsumingPositionIterator::SubsumingPositionIterator(const IRPosition &IRP) {
IRPositions.emplace_back(IRP);
ImmutableCallSite ICS(&IRP.getAnchorValue());
switch (IRP.getPositionKind()) {
case IRPosition::IRP_INVALID:
case IRPosition::IRP_FLOAT:
case IRPosition::IRP_FUNCTION:
return;
case IRPosition::IRP_ARGUMENT:
case IRPosition::IRP_RETURNED:
IRPositions.emplace_back(
IRPosition::function(*IRP.getAssociatedFunction()));
return;
case IRPosition::IRP_CALL_SITE:
assert(ICS && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!ICS.hasOperandBundles())
if (const Function *Callee = ICS.getCalledFunction())
IRPositions.emplace_back(IRPosition::function(*Callee));
return;
case IRPosition::IRP_CALL_SITE_RETURNED:
assert(ICS && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!ICS.hasOperandBundles()) {
if (const Function *Callee = ICS.getCalledFunction()) {
IRPositions.emplace_back(IRPosition::returned(*Callee));
IRPositions.emplace_back(IRPosition::function(*Callee));
}
}
IRPositions.emplace_back(
IRPosition::callsite_function(cast<CallBase>(*ICS.getInstruction())));
return;
case IRPosition::IRP_CALL_SITE_ARGUMENT: {
int ArgNo = IRP.getArgNo();
assert(ICS && ArgNo >= 0 && "Expected call site!");
// TODO: We need to look at the operand bundles similar to the redirection
// in CallBase.
if (!ICS.hasOperandBundles()) {
const Function *Callee = ICS.getCalledFunction();
if (Callee && Callee->arg_size() > unsigned(ArgNo))
IRPositions.emplace_back(IRPosition::argument(*Callee->getArg(ArgNo)));
if (Callee)
IRPositions.emplace_back(IRPosition::function(*Callee));
}
IRPositions.emplace_back(IRPosition::value(IRP.getAssociatedValue()));
return;
}
}
}
bool IRPosition::hasAttr(ArrayRef<Attribute::AttrKind> AKs,
bool IgnoreSubsumingPositions) const {
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs)
if (EquivIRP.getAttr(AK).getKindAsEnum() == AK)
return true;
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
return false;
}
void IRPosition::getAttrs(ArrayRef<Attribute::AttrKind> AKs,
SmallVectorImpl<Attribute> &Attrs,
bool IgnoreSubsumingPositions) const {
for (const IRPosition &EquivIRP : SubsumingPositionIterator(*this)) {
for (Attribute::AttrKind AK : AKs) {
const Attribute &Attr = EquivIRP.getAttr(AK);
if (Attr.getKindAsEnum() == AK)
Attrs.push_back(Attr);
}
// The first position returned by the SubsumingPositionIterator is
// always the position itself. If we ignore subsuming positions we
// are done after the first iteration.
if (IgnoreSubsumingPositions)
break;
}
}
void IRPosition::verify() {
switch (KindOrArgNo) {
default:
assert(KindOrArgNo >= 0 && "Expected argument or call site argument!");
assert((isa<CallBase>(AnchorVal) || isa<Argument>(AnchorVal)) &&
"Expected call base or argument for positive attribute index!");
if (isa<Argument>(AnchorVal)) {
assert(cast<Argument>(AnchorVal)->getArgNo() == unsigned(getArgNo()) &&
"Argument number mismatch!");
assert(cast<Argument>(AnchorVal) == &getAssociatedValue() &&
"Associated value mismatch!");
} else {
assert(cast<CallBase>(*AnchorVal).arg_size() > unsigned(getArgNo()) &&
"Call site argument number mismatch!");
assert(cast<CallBase>(*AnchorVal).getArgOperand(getArgNo()) ==
&getAssociatedValue() &&
"Associated value mismatch!");
}
break;
case IRP_INVALID:
assert(!AnchorVal && "Expected no value for an invalid position!");
break;
case IRP_FLOAT:
assert((!isa<CallBase>(&getAssociatedValue()) &&
!isa<Argument>(&getAssociatedValue())) &&
"Expected specialized kind for call base and argument values!");
break;
case IRP_RETURNED:
assert(isa<Function>(AnchorVal) &&
"Expected function for a 'returned' position!");
assert(AnchorVal == &getAssociatedValue() && "Associated value mismatch!");
break;
case IRP_CALL_SITE_RETURNED:
assert((isa<CallBase>(AnchorVal)) &&
"Expected call base for 'call site returned' position!");
assert(AnchorVal == &getAssociatedValue() && "Associated value mismatch!");
break;
case IRP_CALL_SITE:
assert((isa<CallBase>(AnchorVal)) &&
"Expected call base for 'call site function' position!");
assert(AnchorVal == &getAssociatedValue() && "Associated value mismatch!");
break;
case IRP_FUNCTION:
assert(isa<Function>(AnchorVal) &&
"Expected function for a 'function' position!");
assert(AnchorVal == &getAssociatedValue() && "Associated value mismatch!");
break;
}
}
namespace {
/// Helper function to clamp a state \p S of type \p StateType with the
/// information in \p R and indicate/return if \p S did change (as-in update is
/// required to be run again).
template <typename StateType>
ChangeStatus clampStateAndIndicateChange(StateType &S, const StateType &R) {
auto Assumed = S.getAssumed();
S ^= R;
return Assumed == S.getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// Clamp the information known for all returned values of a function
/// (identified by \p QueryingAA) into \p S.
template <typename AAType, typename StateType = typename AAType::StateType>
static void clampReturnedValueStates(Attributor &A, const AAType &QueryingAA,
StateType &S) {
LLVM_DEBUG(dbgs() << "[Attributor] Clamp return value states for "
<< QueryingAA << " into " << S << "\n");
assert((QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_RETURNED ||
QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_CALL_SITE_RETURNED) &&
"Can only clamp returned value states for a function returned or call "
"site returned position!");
// Use an optional state as there might not be any return values and we want
// to join (IntegerState::operator&) the state of all there are.
Optional<StateType> T;
// Callback for each possibly returned value.
auto CheckReturnValue = [&](Value &RV) -> bool {
const IRPosition &RVPos = IRPosition::value(RV);
const AAType &AA = A.getAAFor<AAType>(QueryingAA, RVPos);
LLVM_DEBUG(dbgs() << "[Attributor] RV: " << RV << " AA: " << AA.getAsStr()
<< " @ " << RVPos << "\n");
const StateType &AAS = static_cast<const StateType &>(AA.getState());
if (T.hasValue())
*T &= AAS;
else
T = AAS;
LLVM_DEBUG(dbgs() << "[Attributor] AA State: " << AAS << " RV State: " << T
<< "\n");
return T->isValidState();
};
if (!A.checkForAllReturnedValues(CheckReturnValue, QueryingAA))
S.indicatePessimisticFixpoint();
else if (T.hasValue())
S ^= *T;
}
/// Helper class to compose two generic deduction
template <typename AAType, typename Base, typename StateType,
template <typename...> class F, template <typename...> class G>
struct AAComposeTwoGenericDeduction
: public F<AAType, G<AAType, Base, StateType>, StateType> {
AAComposeTwoGenericDeduction(const IRPosition &IRP)
: F<AAType, G<AAType, Base, StateType>, StateType>(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus ChangedF =
F<AAType, G<AAType, Base, StateType>, StateType>::updateImpl(A);
ChangeStatus ChangedG = G<AAType, Base, StateType>::updateImpl(A);
return ChangedF | ChangedG;
}
};
/// Helper class for generic deduction: return value -> returned position.
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
struct AAReturnedFromReturnedValues : public Base {
AAReturnedFromReturnedValues(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
StateType S;
clampReturnedValueStates<AAType, StateType>(A, *this, S);
// TODO: If we know we visited all returned values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange<StateType>(this->getState(), S);
}
};
/// Clamp the information known at all call sites for a given argument
/// (identified by \p QueryingAA) into \p S.
template <typename AAType, typename StateType = typename AAType::StateType>
static void clampCallSiteArgumentStates(Attributor &A, const AAType &QueryingAA,
StateType &S) {
LLVM_DEBUG(dbgs() << "[Attributor] Clamp call site argument states for "
<< QueryingAA << " into " << S << "\n");
assert(QueryingAA.getIRPosition().getPositionKind() ==
IRPosition::IRP_ARGUMENT &&
"Can only clamp call site argument states for an argument position!");
// Use an optional state as there might not be any return values and we want
// to join (IntegerState::operator&) the state of all there are.
Optional<StateType> T;
// The argument number which is also the call site argument number.
unsigned ArgNo = QueryingAA.getIRPosition().getArgNo();
auto CallSiteCheck = [&](AbstractCallSite ACS) {
const IRPosition &ACSArgPos = IRPosition::callsite_argument(ACS, ArgNo);
// Check if a coresponding argument was found or if it is on not associated
// (which can happen for callback calls).
if (ACSArgPos.getPositionKind() == IRPosition::IRP_INVALID)
return false;
const AAType &AA = A.getAAFor<AAType>(QueryingAA, ACSArgPos);
LLVM_DEBUG(dbgs() << "[Attributor] ACS: " << *ACS.getInstruction()
<< " AA: " << AA.getAsStr() << " @" << ACSArgPos << "\n");
const StateType &AAS = static_cast<const StateType &>(AA.getState());
if (T.hasValue())
*T &= AAS;
else
T = AAS;
LLVM_DEBUG(dbgs() << "[Attributor] AA State: " << AAS << " CSA State: " << T
<< "\n");
return T->isValidState();
};
if (!A.checkForAllCallSites(CallSiteCheck, QueryingAA, true))
S.indicatePessimisticFixpoint();
else if (T.hasValue())
S ^= *T;
}
/// Helper class for generic deduction: call site argument -> argument position.
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
struct AAArgumentFromCallSiteArguments : public Base {
AAArgumentFromCallSiteArguments(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
StateType S;
clampCallSiteArgumentStates<AAType, StateType>(A, *this, S);
// TODO: If we know we visited all incoming values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange<StateType>(this->getState(), S);
}
};
/// Helper class for generic replication: function returned -> cs returned.
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
struct AACallSiteReturnedFromReturned : public Base {
AACallSiteReturnedFromReturned(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
assert(this->getIRPosition().getPositionKind() ==
IRPosition::IRP_CALL_SITE_RETURNED &&
"Can only wrap function returned positions for call site returned "
"positions!");
auto &S = this->getState();
const Function *AssociatedFunction =
this->getIRPosition().getAssociatedFunction();
if (!AssociatedFunction)
return S.indicatePessimisticFixpoint();
IRPosition FnPos = IRPosition::returned(*AssociatedFunction);
const AAType &AA = A.getAAFor<AAType>(*this, FnPos);
return clampStateAndIndicateChange(
S, static_cast<const typename AAType::StateType &>(AA.getState()));
}
};
/// Helper class for generic deduction using must-be-executed-context
/// Base class is required to have `followUse` method.
/// bool followUse(Attributor &A, const Use *U, const Instruction *I)
/// U - Underlying use.
/// I - The user of the \p U.
/// `followUse` returns true if the value should be tracked transitively.
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
struct AAFromMustBeExecutedContext : public Base {
AAFromMustBeExecutedContext(const IRPosition &IRP) : Base(IRP) {}
void initialize(Attributor &A) override {
Base::initialize(A);
const IRPosition &IRP = this->getIRPosition();
Instruction *CtxI = IRP.getCtxI();
if (!CtxI)
return;
for (const Use &U : IRP.getAssociatedValue().uses())
Uses.insert(&U);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto BeforeState = this->getState();
auto &S = this->getState();
Instruction *CtxI = this->getIRPosition().getCtxI();
if (!CtxI)
return ChangeStatus::UNCHANGED;
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
auto EIt = Explorer.begin(CtxI), EEnd = Explorer.end(CtxI);
for (unsigned u = 0; u < Uses.size(); ++u) {
const Use *U = Uses[u];
if (const Instruction *UserI = dyn_cast<Instruction>(U->getUser())) {
bool Found = Explorer.findInContextOf(UserI, EIt, EEnd);
if (Found && Base::followUse(A, U, UserI))
for (const Use &Us : UserI->uses())
Uses.insert(&Us);
}
}
return BeforeState == S ? ChangeStatus::UNCHANGED : ChangeStatus::CHANGED;
}
private:
/// Container for (transitive) uses of the associated value.
SetVector<const Use *> Uses;
};
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
using AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext =
AAComposeTwoGenericDeduction<AAType, Base, StateType,
AAFromMustBeExecutedContext,
AAArgumentFromCallSiteArguments>;
template <typename AAType, typename Base,
typename StateType = typename AAType::StateType>
using AACallSiteReturnedFromReturnedAndMustBeExecutedContext =
AAComposeTwoGenericDeduction<AAType, Base, StateType,
AAFromMustBeExecutedContext,
AACallSiteReturnedFromReturned>;
/// -----------------------NoUnwind Function Attribute--------------------------
struct AANoUnwindImpl : AANoUnwind {
AANoUnwindImpl(const IRPosition &IRP) : AANoUnwind(IRP) {}
const std::string getAsStr() const override {
return getAssumed() ? "nounwind" : "may-unwind";
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto Opcodes = {
(unsigned)Instruction::Invoke, (unsigned)Instruction::CallBr,
(unsigned)Instruction::Call, (unsigned)Instruction::CleanupRet,
(unsigned)Instruction::CatchSwitch, (unsigned)Instruction::Resume};
auto CheckForNoUnwind = [&](Instruction &I) {
if (!I.mayThrow())
return true;
if (ImmutableCallSite ICS = ImmutableCallSite(&I)) {
const auto &NoUnwindAA =
A.getAAFor<AANoUnwind>(*this, IRPosition::callsite_function(ICS));
return NoUnwindAA.isAssumedNoUnwind();
}
return false;
};
if (!A.checkForAllInstructions(CheckForNoUnwind, *this, Opcodes))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
struct AANoUnwindFunction final : public AANoUnwindImpl {
AANoUnwindFunction(const IRPosition &IRP) : AANoUnwindImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nounwind) }
};
/// NoUnwind attribute deduction for a call sites.
struct AANoUnwindCallSite final : AANoUnwindImpl {
AANoUnwindCallSite(const IRPosition &IRP) : AANoUnwindImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoUnwindImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoUnwind>(*this, FnPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AANoUnwind::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nounwind); }
};
/// --------------------- Function Return Values -------------------------------
/// "Attribute" that collects all potential returned values and the return
/// instructions that they arise from.
///
/// If there is a unique returned value R, the manifest method will:
/// - mark R with the "returned" attribute, if R is an argument.
class AAReturnedValuesImpl : public AAReturnedValues, public AbstractState {
/// Mapping of values potentially returned by the associated function to the
/// return instructions that might return them.
MapVector<Value *, SmallSetVector<ReturnInst *, 4>> ReturnedValues;
/// Mapping to remember the number of returned values for a call site such
/// that we can avoid updates if nothing changed.
DenseMap<const CallBase *, unsigned> NumReturnedValuesPerKnownAA;
/// Set of unresolved calls returned by the associated function.
SmallSetVector<CallBase *, 4> UnresolvedCalls;
/// State flags
///
///{
bool IsFixed = false;
bool IsValidState = true;
///}
public:
AAReturnedValuesImpl(const IRPosition &IRP) : AAReturnedValues(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// Reset the state.
IsFixed = false;
IsValidState = true;
ReturnedValues.clear();
Function *F = getAssociatedFunction();
if (!F) {
indicatePessimisticFixpoint();
return;
}
// The map from instruction opcodes to those instructions in the function.
auto &OpcodeInstMap = A.getInfoCache().getOpcodeInstMapForFunction(*F);
// Look through all arguments, if one is marked as returned we are done.
for (Argument &Arg : F->args()) {
if (Arg.hasReturnedAttr()) {
auto &ReturnInstSet = ReturnedValues[&Arg];
for (Instruction *RI : OpcodeInstMap[Instruction::Ret])
ReturnInstSet.insert(cast<ReturnInst>(RI));
indicateOptimisticFixpoint();
return;
}
}
if (!F->hasExactDefinition())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override;
/// See AbstractAttribute::getState(...).
AbstractState &getState() override { return *this; }
/// See AbstractAttribute::getState(...).
const AbstractState &getState() const override { return *this; }
/// See AbstractAttribute::updateImpl(Attributor &A).
ChangeStatus updateImpl(Attributor &A) override;
llvm::iterator_range<iterator> returned_values() override {
return llvm::make_range(ReturnedValues.begin(), ReturnedValues.end());
}
llvm::iterator_range<const_iterator> returned_values() const override {
return llvm::make_range(ReturnedValues.begin(), ReturnedValues.end());
}
const SmallSetVector<CallBase *, 4> &getUnresolvedCalls() const override {
return UnresolvedCalls;
}
/// Return the number of potential return values, -1 if unknown.
size_t getNumReturnValues() const override {
return isValidState() ? ReturnedValues.size() : -1;
}
/// Return an assumed unique return value if a single candidate is found. If
/// there cannot be one, return a nullptr. If it is not clear yet, return the
/// Optional::NoneType.
Optional<Value *> getAssumedUniqueReturnValue(Attributor &A) const;
/// See AbstractState::checkForAllReturnedValues(...).
bool checkForAllReturnedValuesAndReturnInsts(
const function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)>
&Pred) const override;
/// Pretty print the attribute similar to the IR representation.
const std::string getAsStr() const override;
/// See AbstractState::isAtFixpoint().
bool isAtFixpoint() const override { return IsFixed; }
/// See AbstractState::isValidState().
bool isValidState() const override { return IsValidState; }
/// See AbstractState::indicateOptimisticFixpoint(...).
ChangeStatus indicateOptimisticFixpoint() override {
IsFixed = true;
return ChangeStatus::UNCHANGED;
}
ChangeStatus indicatePessimisticFixpoint() override {
IsFixed = true;
IsValidState = false;
return ChangeStatus::CHANGED;
}
};
ChangeStatus AAReturnedValuesImpl::manifest(Attributor &A) {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
// Bookkeeping.
assert(isValidState());
STATS_DECLTRACK(KnownReturnValues, FunctionReturn,
"Number of function with known return values");
// Check if we have an assumed unique return value that we could manifest.
Optional<Value *> UniqueRV = getAssumedUniqueReturnValue(A);
if (!UniqueRV.hasValue() || !UniqueRV.getValue())
return Changed;
// Bookkeeping.
STATS_DECLTRACK(UniqueReturnValue, FunctionReturn,
"Number of function with unique return");
// Callback to replace the uses of CB with the constant C.
auto ReplaceCallSiteUsersWith = [](CallBase &CB, Constant &C) {
if (CB.getNumUses() == 0 || CB.isMustTailCall())
return ChangeStatus::UNCHANGED;
replaceAllInstructionUsesWith(CB, C);
return ChangeStatus::CHANGED;
};
// If the assumed unique return value is an argument, annotate it.
if (auto *UniqueRVArg = dyn_cast<Argument>(UniqueRV.getValue())) {
// TODO: This should be handled differently!
this->AnchorVal = UniqueRVArg;
this->KindOrArgNo = UniqueRVArg->getArgNo();
Changed = IRAttribute::manifest(A);
} else if (auto *RVC = dyn_cast<Constant>(UniqueRV.getValue())) {
// We can replace the returned value with the unique returned constant.
Value &AnchorValue = getAnchorValue();
if (Function *F = dyn_cast<Function>(&AnchorValue)) {
for (const Use &U : F->uses())
if (CallBase *CB = dyn_cast<CallBase>(U.getUser()))
if (CB->isCallee(&U)) {
Constant *RVCCast =
CB->getType() == RVC->getType()
? RVC
: ConstantExpr::getTruncOrBitCast(RVC, CB->getType());
Changed = ReplaceCallSiteUsersWith(*CB, *RVCCast) | Changed;
}
} else {
assert(isa<CallBase>(AnchorValue) &&
"Expcected a function or call base anchor!");
Constant *RVCCast =
AnchorValue.getType() == RVC->getType()
? RVC
: ConstantExpr::getTruncOrBitCast(RVC, AnchorValue.getType());
Changed = ReplaceCallSiteUsersWith(cast<CallBase>(AnchorValue), *RVCCast);
}
if (Changed == ChangeStatus::CHANGED)
STATS_DECLTRACK(UniqueConstantReturnValue, FunctionReturn,
"Number of function returns replaced by constant return");
}
return Changed;
}
const std::string AAReturnedValuesImpl::getAsStr() const {
return (isAtFixpoint() ? "returns(#" : "may-return(#") +
(isValidState() ? std::to_string(getNumReturnValues()) : "?") +
")[#UC: " + std::to_string(UnresolvedCalls.size()) + "]";
}
Optional<Value *>
AAReturnedValuesImpl::getAssumedUniqueReturnValue(Attributor &A) const {
// If checkForAllReturnedValues provides a unique value, ignoring potential
// undef values that can also be present, it is assumed to be the actual
// return value and forwarded to the caller of this method. If there are
// multiple, a nullptr is returned indicating there cannot be a unique
// returned value.
Optional<Value *> UniqueRV;
auto Pred = [&](Value &RV) -> bool {
// If we found a second returned value and neither the current nor the saved
// one is an undef, there is no unique returned value. Undefs are special
// since we can pretend they have any value.
if (UniqueRV.hasValue() && UniqueRV != &RV &&
!(isa<UndefValue>(RV) || isa<UndefValue>(UniqueRV.getValue()))) {
UniqueRV = nullptr;
return false;
}
// Do not overwrite a value with an undef.
if (!UniqueRV.hasValue() || !isa<UndefValue>(RV))
UniqueRV = &RV;
return true;
};
if (!A.checkForAllReturnedValues(Pred, *this))
UniqueRV = nullptr;
return UniqueRV;
}
bool AAReturnedValuesImpl::checkForAllReturnedValuesAndReturnInsts(
const function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)>
&Pred) const {
if (!isValidState())
return false;
// Check all returned values but ignore call sites as long as we have not
// encountered an overdefined one during an update.
for (auto &It : ReturnedValues) {
Value *RV = It.first;
CallBase *CB = dyn_cast<CallBase>(RV);
if (CB && !UnresolvedCalls.count(CB))
continue;
if (!Pred(*RV, It.second))
return false;
}
return true;
}
ChangeStatus AAReturnedValuesImpl::updateImpl(Attributor &A) {
size_t NumUnresolvedCalls = UnresolvedCalls.size();
bool Changed = false;
// State used in the value traversals starting in returned values.
struct RVState {
// The map in which we collect return values -> return instrs.
decltype(ReturnedValues) &RetValsMap;
// The flag to indicate a change.
bool &Changed;
// The return instrs we come from.
SmallSetVector<ReturnInst *, 4> RetInsts;
};
// Callback for a leaf value returned by the associated function.
auto VisitValueCB = [](Value &Val, RVState &RVS, bool) -> bool {
auto Size = RVS.RetValsMap[&Val].size();
RVS.RetValsMap[&Val].insert(RVS.RetInsts.begin(), RVS.RetInsts.end());
bool Inserted = RVS.RetValsMap[&Val].size() != Size;
RVS.Changed |= Inserted;
LLVM_DEBUG({
if (Inserted)
dbgs() << "[AAReturnedValues] 1 Add new returned value " << Val
<< " => " << RVS.RetInsts.size() << "\n";
});
return true;
};
// Helper method to invoke the generic value traversal.
auto VisitReturnedValue = [&](Value &RV, RVState &RVS) {
IRPosition RetValPos = IRPosition::value(RV);
return genericValueTraversal<AAReturnedValues, RVState>(A, RetValPos, *this,
RVS, VisitValueCB);
};
// Callback for all "return intructions" live in the associated function.
auto CheckReturnInst = [this, &VisitReturnedValue, &Changed](Instruction &I) {
ReturnInst &Ret = cast<ReturnInst>(I);
RVState RVS({ReturnedValues, Changed, {}});
RVS.RetInsts.insert(&Ret);
return VisitReturnedValue(*Ret.getReturnValue(), RVS);
};
// Start by discovering returned values from all live returned instructions in
// the associated function.
if (!A.checkForAllInstructions(CheckReturnInst, *this, {Instruction::Ret}))
return indicatePessimisticFixpoint();
// Once returned values "directly" present in the code are handled we try to
// resolve returned calls.
decltype(ReturnedValues) NewRVsMap;
for (auto &It : ReturnedValues) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Returned value: " << *It.first
<< " by #" << It.second.size() << " RIs\n");
CallBase *CB = dyn_cast<CallBase>(It.first);
if (!CB || UnresolvedCalls.count(CB))
continue;
if (!CB->getCalledFunction()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Unresolved call: " << *CB
<< "\n");
UnresolvedCalls.insert(CB);
continue;
}
// TODO: use the function scope once we have call site AAReturnedValues.
const auto &RetValAA = A.getAAFor<AAReturnedValues>(
*this, IRPosition::function(*CB->getCalledFunction()));
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Found another AAReturnedValues: "
<< RetValAA << "\n");
// Skip dead ends, thus if we do not know anything about the returned
// call we mark it as unresolved and it will stay that way.
if (!RetValAA.getState().isValidState()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Unresolved call: " << *CB
<< "\n");
UnresolvedCalls.insert(CB);
continue;
}
// Do not try to learn partial information. If the callee has unresolved
// return values we will treat the call as unresolved/opaque.
auto &RetValAAUnresolvedCalls = RetValAA.getUnresolvedCalls();
if (!RetValAAUnresolvedCalls.empty()) {
UnresolvedCalls.insert(CB);
continue;
}
// Now check if we can track transitively returned values. If possible, thus
// if all return value can be represented in the current scope, do so.
bool Unresolved = false;
for (auto &RetValAAIt : RetValAA.returned_values()) {
Value *RetVal = RetValAAIt.first;
if (isa<Argument>(RetVal) || isa<CallBase>(RetVal) ||
isa<Constant>(RetVal))
continue;
// Anything that did not fit in the above categories cannot be resolved,
// mark the call as unresolved.
LLVM_DEBUG(dbgs() << "[AAReturnedValues] transitively returned value "
"cannot be translated: "
<< *RetVal << "\n");
UnresolvedCalls.insert(CB);
Unresolved = true;
break;
}
if (Unresolved)
continue;
// Now track transitively returned values.
unsigned &NumRetAA = NumReturnedValuesPerKnownAA[CB];
if (NumRetAA == RetValAA.getNumReturnValues()) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Skip call as it has not "
"changed since it was seen last\n");
continue;
}
NumRetAA = RetValAA.getNumReturnValues();
for (auto &RetValAAIt : RetValAA.returned_values()) {
Value *RetVal = RetValAAIt.first;
if (Argument *Arg = dyn_cast<Argument>(RetVal)) {
// Arguments are mapped to call site operands and we begin the traversal
// again.
bool Unused = false;
RVState RVS({NewRVsMap, Unused, RetValAAIt.second});
VisitReturnedValue(*CB->getArgOperand(Arg->getArgNo()), RVS);
continue;
} else if (isa<CallBase>(RetVal)) {
// Call sites are resolved by the callee attribute over time, no need to
// do anything for us.
continue;
} else if (isa<Constant>(RetVal)) {
// Constants are valid everywhere, we can simply take them.
NewRVsMap[RetVal].insert(It.second.begin(), It.second.end());
continue;
}
}
}
// To avoid modifications to the ReturnedValues map while we iterate over it
// we kept record of potential new entries in a copy map, NewRVsMap.
for (auto &It : NewRVsMap) {
assert(!It.second.empty() && "Entry does not add anything.");
auto &ReturnInsts = ReturnedValues[It.first];
for (ReturnInst *RI : It.second)
if (ReturnInsts.insert(RI)) {
LLVM_DEBUG(dbgs() << "[AAReturnedValues] Add new returned value "
<< *It.first << " => " << *RI << "\n");
Changed = true;
}
}
Changed |= (NumUnresolvedCalls != UnresolvedCalls.size());
return Changed ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
struct AAReturnedValuesFunction final : public AAReturnedValuesImpl {
AAReturnedValuesFunction(const IRPosition &IRP) : AAReturnedValuesImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(returned) }
};
/// Returned values information for a call sites.
struct AAReturnedValuesCallSite final : AAReturnedValuesImpl {
AAReturnedValuesCallSite(const IRPosition &IRP) : AAReturnedValuesImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites instead of
// redirecting requests to the callee.
llvm_unreachable("Abstract attributes for returned values are not "
"supported for call sites yet!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// ------------------------ NoSync Function Attribute -------------------------
struct AANoSyncImpl : AANoSync {
AANoSyncImpl(const IRPosition &IRP) : AANoSync(IRP) {}
const std::string getAsStr() const override {
return getAssumed() ? "nosync" : "may-sync";
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// Helper function used to determine whether an instruction is non-relaxed
/// atomic. In other words, if an atomic instruction does not have unordered
/// or monotonic ordering
static bool isNonRelaxedAtomic(Instruction *I);
/// Helper function used to determine whether an instruction is volatile.
static bool isVolatile(Instruction *I);
/// Helper function uset to check if intrinsic is volatile (memcpy, memmove,
/// memset).
static bool isNoSyncIntrinsic(Instruction *I);
};
bool AANoSyncImpl::isNonRelaxedAtomic(Instruction *I) {
if (!I->isAtomic())
return false;
AtomicOrdering Ordering;
switch (I->getOpcode()) {
case Instruction::AtomicRMW:
Ordering = cast<AtomicRMWInst>(I)->getOrdering();
break;
case Instruction::Store:
Ordering = cast<StoreInst>(I)->getOrdering();
break;
case Instruction::Load:
Ordering = cast<LoadInst>(I)->getOrdering();
break;
case Instruction::Fence: {
auto *FI = cast<FenceInst>(I);
if (FI->getSyncScopeID() == SyncScope::SingleThread)
return false;
Ordering = FI->getOrdering();
break;
}
case Instruction::AtomicCmpXchg: {
AtomicOrdering Success = cast<AtomicCmpXchgInst>(I)->getSuccessOrdering();
AtomicOrdering Failure = cast<AtomicCmpXchgInst>(I)->getFailureOrdering();
// Only if both are relaxed, than it can be treated as relaxed.
// Otherwise it is non-relaxed.
if (Success != AtomicOrdering::Unordered &&
Success != AtomicOrdering::Monotonic)
return true;
if (Failure != AtomicOrdering::Unordered &&
Failure != AtomicOrdering::Monotonic)
return true;
return false;
}
default:
llvm_unreachable(
"New atomic operations need to be known in the attributor.");
}
// Relaxed.
if (Ordering == AtomicOrdering::Unordered ||
Ordering == AtomicOrdering::Monotonic)
return false;
return true;
}
/// Checks if an intrinsic is nosync. Currently only checks mem* intrinsics.
/// FIXME: We should ipmrove the handling of intrinsics.
bool AANoSyncImpl::isNoSyncIntrinsic(Instruction *I) {
if (auto *II = dyn_cast<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) {
/// Element wise atomic memory intrinsics are can only be unordered,
/// therefore nosync.
case Intrinsic::memset_element_unordered_atomic:
case Intrinsic::memmove_element_unordered_atomic:
case Intrinsic::memcpy_element_unordered_atomic:
return true;
case Intrinsic::memset:
case Intrinsic::memmove:
case Intrinsic::memcpy:
if (!cast<MemIntrinsic>(II)->isVolatile())
return true;
return false;
default:
return false;
}
}
return false;
}
bool AANoSyncImpl::isVolatile(Instruction *I) {
assert(!ImmutableCallSite(I) && !isa<CallBase>(I) &&
"Calls should not be checked here");
switch (I->getOpcode()) {
case Instruction::AtomicRMW:
return cast<AtomicRMWInst>(I)->isVolatile();
case Instruction::Store:
return cast<StoreInst>(I)->isVolatile();
case Instruction::Load:
return cast<LoadInst>(I)->isVolatile();
case Instruction::AtomicCmpXchg:
return cast<AtomicCmpXchgInst>(I)->isVolatile();
default:
return false;
}
}
ChangeStatus AANoSyncImpl::updateImpl(Attributor &A) {
auto CheckRWInstForNoSync = [&](Instruction &I) {
/// We are looking for volatile instructions or Non-Relaxed atomics.
/// FIXME: We should improve the handling of intrinsics.
if (isa<IntrinsicInst>(&I) && isNoSyncIntrinsic(&I))
return true;
if (ImmutableCallSite ICS = ImmutableCallSite(&I)) {
if (ICS.hasFnAttr(Attribute::NoSync))
return true;
const auto &NoSyncAA =
A.getAAFor<AANoSync>(*this, IRPosition::callsite_function(ICS));
if (NoSyncAA.isAssumedNoSync())
return true;
return false;
}
if (!isVolatile(&I) && !isNonRelaxedAtomic(&I))
return true;
return false;
};
auto CheckForNoSync = [&](Instruction &I) {
// At this point we handled all read/write effects and they are all
// nosync, so they can be skipped.
if (I.mayReadOrWriteMemory())
return true;
// non-convergent and readnone imply nosync.
return !ImmutableCallSite(&I).isConvergent();
};
if (!A.checkForAllReadWriteInstructions(CheckRWInstForNoSync, *this) ||
!A.checkForAllCallLikeInstructions(CheckForNoSync, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
struct AANoSyncFunction final : public AANoSyncImpl {
AANoSyncFunction(const IRPosition &IRP) : AANoSyncImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nosync) }
};
/// NoSync attribute deduction for a call sites.
struct AANoSyncCallSite final : AANoSyncImpl {
AANoSyncCallSite(const IRPosition &IRP) : AANoSyncImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoSyncImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoSync>(*this, FnPos);
return clampStateAndIndicateChange(
getState(), static_cast<const AANoSync::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nosync); }
};
/// ------------------------ No-Free Attributes ----------------------------
struct AANoFreeImpl : public AANoFree {
AANoFreeImpl(const IRPosition &IRP) : AANoFree(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto CheckForNoFree = [&](Instruction &I) {
ImmutableCallSite ICS(&I);
if (ICS.hasFnAttr(Attribute::NoFree))
return true;
const auto &NoFreeAA =
A.getAAFor<AANoFree>(*this, IRPosition::callsite_function(ICS));
return NoFreeAA.isAssumedNoFree();
};
if (!A.checkForAllCallLikeInstructions(CheckForNoFree, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "nofree" : "may-free";
}
};
struct AANoFreeFunction final : public AANoFreeImpl {
AANoFreeFunction(const IRPosition &IRP) : AANoFreeImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(nofree) }
};
/// NoFree attribute deduction for a call sites.
struct AANoFreeCallSite final : AANoFreeImpl {
AANoFreeCallSite(const IRPosition &IRP) : AANoFreeImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoFreeImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoFree>(*this, FnPos);
return clampStateAndIndicateChange(
getState(), static_cast<const AANoFree::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(nofree); }
};
/// NoFree attribute for floating values.
struct AANoFreeFloating : AANoFreeImpl {
AANoFreeFloating(const IRPosition &IRP) : AANoFreeImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_FLOATING_ATTR(nofree)}
/// See Abstract Attribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
const IRPosition &IRP = getIRPosition();
const auto &NoFreeAA =
A.getAAFor<AANoFree>(*this, IRPosition::function_scope(IRP));
if (NoFreeAA.isAssumedNoFree())
return ChangeStatus::UNCHANGED;
Value &AssociatedValue = getIRPosition().getAssociatedValue();
auto Pred = [&](const Use &U, bool &Follow) -> bool {
Instruction *UserI = cast<Instruction>(U.getUser());
if (auto *CB = dyn_cast<CallBase>(UserI)) {
if (CB->isBundleOperand(&U))
return false;
if (!CB->isArgOperand(&U))
return true;
unsigned ArgNo = CB->getArgOperandNo(&U);
const auto &NoFreeArg = A.getAAFor<AANoFree>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
return NoFreeArg.isAssumedNoFree();
}
if (isa<GetElementPtrInst>(UserI) || isa<BitCastInst>(UserI) ||
isa<PHINode>(UserI) || isa<SelectInst>(UserI)) {
Follow = true;
return true;
}
// Unknown user.
return false;
};
if (!A.checkForAllUses(Pred, *this, AssociatedValue))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
/// NoFree attribute for a call site argument.
struct AANoFreeArgument final : AANoFreeFloating {
AANoFreeArgument(const IRPosition &IRP) : AANoFreeFloating(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nofree) }
};
/// NoFree attribute for call site arguments.
struct AANoFreeCallSiteArgument final : AANoFreeFloating {
AANoFreeCallSiteArgument(const IRPosition &IRP) : AANoFreeFloating(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AANoFree>(*this, ArgPos);
return clampStateAndIndicateChange(
getState(), static_cast<const AANoFree::StateType &>(ArgAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_CSARG_ATTR(nofree)};
};
/// NoFree attribute for function return value.
struct AANoFreeReturned final : AANoFreeFloating {
AANoFreeReturned(const IRPosition &IRP) : AANoFreeFloating(IRP) {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("NoFree is not applicable to function returns!");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// NoFree attribute deduction for a call site return value.
struct AANoFreeCallSiteReturned final : AANoFreeFloating {
AANoFreeCallSiteReturned(const IRPosition &IRP) : AANoFreeFloating(IRP) {}
ChangeStatus manifest(Attributor &A) override {
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(nofree) }
};
/// ------------------------ NonNull Argument Attribute ------------------------
static int64_t getKnownNonNullAndDerefBytesForUse(
Attributor &A, AbstractAttribute &QueryingAA, Value &AssociatedValue,
const Use *U, const Instruction *I, bool &IsNonNull, bool &TrackUse) {
TrackUse = false;
const Value *UseV = U->get();
if (!UseV->getType()->isPointerTy())
return 0;
Type *PtrTy = UseV->getType();
const Function *F = I->getFunction();
bool NullPointerIsDefined =
F ? llvm::NullPointerIsDefined(F, PtrTy->getPointerAddressSpace()) : true;
const DataLayout &DL = A.getInfoCache().getDL();
if (ImmutableCallSite ICS = ImmutableCallSite(I)) {
if (ICS.isBundleOperand(U))
return 0;
if (ICS.isCallee(U)) {
IsNonNull |= !NullPointerIsDefined;
return 0;
}
unsigned ArgNo = ICS.getArgumentNo(U);
IRPosition IRP = IRPosition::callsite_argument(ICS, ArgNo);
// As long as we only use known information there is no need to track
// dependences here.
auto &DerefAA = A.getAAFor<AADereferenceable>(QueryingAA, IRP,
/* TrackDependence */ false);
IsNonNull |= DerefAA.isKnownNonNull();
return DerefAA.getKnownDereferenceableBytes();
}
// We need to follow common pointer manipulation uses to the accesses they
// feed into. We can try to be smart to avoid looking through things we do not
// like for now, e.g., non-inbounds GEPs.
if (isa<CastInst>(I)) {
TrackUse = true;
return 0;
}
if (auto *GEP = dyn_cast<GetElementPtrInst>(I))
if (GEP->hasAllConstantIndices()) {
TrackUse = true;
return 0;
}
int64_t Offset;
if (const Value *Base = getBasePointerOfAccessPointerOperand(I, Offset, DL)) {
if (Base == &AssociatedValue &&
Attributor::getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
int64_t DerefBytes =
(int64_t)DL.getTypeStoreSize(PtrTy->getPointerElementType()) + Offset;
IsNonNull |= !NullPointerIsDefined;
return std::max(int64_t(0), DerefBytes);
}
}
/// Corner case when an offset is 0.
if (const Value *Base = getBasePointerOfAccessPointerOperand(
I, Offset, DL, /*AllowNonInbounds*/ true)) {
if (Offset == 0 && Base == &AssociatedValue &&
Attributor::getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
int64_t DerefBytes =
(int64_t)DL.getTypeStoreSize(PtrTy->getPointerElementType());
IsNonNull |= !NullPointerIsDefined;
return std::max(int64_t(0), DerefBytes);
}
}
return 0;
}
struct AANonNullImpl : AANonNull {
AANonNullImpl(const IRPosition &IRP)
: AANonNull(IRP),
NullIsDefined(NullPointerIsDefined(
getAnchorScope(),
getAssociatedValue().getType()->getPointerAddressSpace())) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (!NullIsDefined &&
hasAttr({Attribute::NonNull, Attribute::Dereferenceable}))
indicateOptimisticFixpoint();
else if (isa<ConstantPointerNull>(getAssociatedValue()))
indicatePessimisticFixpoint();
else
AANonNull::initialize(A);
}
/// See AAFromMustBeExecutedContext
bool followUse(Attributor &A, const Use *U, const Instruction *I) {
bool IsNonNull = false;
bool TrackUse = false;
getKnownNonNullAndDerefBytesForUse(A, *this, getAssociatedValue(), U, I,
IsNonNull, TrackUse);
setKnown(IsNonNull);
return TrackUse;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "nonnull" : "may-null";
}
/// Flag to determine if the underlying value can be null and still allow
/// valid accesses.
const bool NullIsDefined;
};
/// NonNull attribute for a floating value.
struct AANonNullFloating
: AAFromMustBeExecutedContext<AANonNull, AANonNullImpl> {
using Base = AAFromMustBeExecutedContext<AANonNull, AANonNullImpl>;
AANonNullFloating(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus Change = Base::updateImpl(A);
if (isKnownNonNull())
return Change;
if (!NullIsDefined) {
const auto &DerefAA =
A.getAAFor<AADereferenceable>(*this, getIRPosition());
if (DerefAA.getAssumedDereferenceableBytes())
return Change;
}
const DataLayout &DL = A.getDataLayout();
DominatorTree *DT = nullptr;
InformationCache &InfoCache = A.getInfoCache();
if (const Function *Fn = getAnchorScope())
DT = InfoCache.getAnalysisResultForFunction<DominatorTreeAnalysis>(*Fn);
auto VisitValueCB = [&](Value &V, AANonNull::StateType &T,
bool Stripped) -> bool {
const auto &AA = A.getAAFor<AANonNull>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
if (!isKnownNonZero(&V, DL, 0, /* TODO: AC */ nullptr, getCtxI(), DT))
T.indicatePessimisticFixpoint();
} else {
// Use abstract attribute information.
const AANonNull::StateType &NS =
static_cast<const AANonNull::StateType &>(AA.getState());
T ^= NS;
}
return T.isValidState();
};
StateType T;
if (!genericValueTraversal<AANonNull, StateType>(A, getIRPosition(), *this,
T, VisitValueCB))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(nonnull) }
};
/// NonNull attribute for function return value.
struct AANonNullReturned final
: AAReturnedFromReturnedValues<AANonNull, AANonNullImpl> {
AANonNullReturned(const IRPosition &IRP)
: AAReturnedFromReturnedValues<AANonNull, AANonNullImpl>(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(nonnull) }
};
/// NonNull attribute for function argument.
struct AANonNullArgument final
: AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<AANonNull,
AANonNullImpl> {
AANonNullArgument(const IRPosition &IRP)
: AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<AANonNull,
AANonNullImpl>(
IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nonnull) }
};
struct AANonNullCallSiteArgument final : AANonNullFloating {
AANonNullCallSiteArgument(const IRPosition &IRP) : AANonNullFloating(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(nonnull) }
};
/// NonNull attribute for a call site return position.
struct AANonNullCallSiteReturned final
: AACallSiteReturnedFromReturnedAndMustBeExecutedContext<AANonNull,
AANonNullImpl> {
AANonNullCallSiteReturned(const IRPosition &IRP)
: AACallSiteReturnedFromReturnedAndMustBeExecutedContext<AANonNull,
AANonNullImpl>(
IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(nonnull) }
};
/// ------------------------ No-Recurse Attributes ----------------------------
struct AANoRecurseImpl : public AANoRecurse {
AANoRecurseImpl(const IRPosition &IRP) : AANoRecurse(IRP) {}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "norecurse" : "may-recurse";
}
};
struct AANoRecurseFunction final : AANoRecurseImpl {
AANoRecurseFunction(const IRPosition &IRP) : AANoRecurseImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoRecurseImpl::initialize(A);
if (const Function *F = getAnchorScope())
if (A.getInfoCache().getSccSize(*F) == 1)
return;
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto CheckForNoRecurse = [&](Instruction &I) {
ImmutableCallSite ICS(&I);
if (ICS.hasFnAttr(Attribute::NoRecurse))
return true;
const auto &NoRecurseAA =
A.getAAFor<AANoRecurse>(*this, IRPosition::callsite_function(ICS));
if (!NoRecurseAA.isAssumedNoRecurse())
return false;
// Recursion to the same function
if (ICS.getCalledFunction() == getAnchorScope())
return false;
return true;
};
if (!A.checkForAllCallLikeInstructions(CheckForNoRecurse, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(norecurse) }
};
/// NoRecurse attribute deduction for a call sites.
struct AANoRecurseCallSite final : AANoRecurseImpl {
AANoRecurseCallSite(const IRPosition &IRP) : AANoRecurseImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoRecurseImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoRecurse>(*this, FnPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AANoRecurse::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(norecurse); }
};
/// -------------------- Undefined-Behavior Attributes ------------------------
struct AAUndefinedBehaviorImpl : public AAUndefinedBehavior {
AAUndefinedBehaviorImpl(const IRPosition &IRP) : AAUndefinedBehavior(IRP) {}
/// See AbstractAttribute::updateImpl(...).
// through a pointer (i.e. also branches etc.)
ChangeStatus updateImpl(Attributor &A) override {
const size_t UBPrevSize = KnownUBInsts.size();
const size_t NoUBPrevSize = AssumedNoUBInsts.size();
auto InspectMemAccessInstForUB = [&](Instruction &I) {
// Skip instructions that are already saved.
if (AssumedNoUBInsts.count(&I) || KnownUBInsts.count(&I))
return true;
// If we reach here, we know we have an instruction
// that accesses memory through a pointer operand,
// for which getPointerOperand() should give it to us.
const Value *PtrOp =
Attributor::getPointerOperand(&I, /* AllowVolatile */ true);
assert(PtrOp &&
"Expected pointer operand of memory accessing instruction");
// A memory access through a pointer is considered UB
// only if the pointer has constant null value.
// TODO: Expand it to not only check constant values.
if (!isa<ConstantPointerNull>(PtrOp)) {
AssumedNoUBInsts.insert(&I);
return true;
}
const Type *PtrTy = PtrOp->getType();
// Because we only consider instructions inside functions,
// assume that a parent function exists.
const Function *F = I.getFunction();
// A memory access using constant null pointer is only considered UB
// if null pointer is _not_ defined for the target platform.
if (llvm::NullPointerIsDefined(F, PtrTy->getPointerAddressSpace()))
AssumedNoUBInsts.insert(&I);
else
KnownUBInsts.insert(&I);
return true;
};
auto InspectBrInstForUB = [&](Instruction &I) {
// A conditional branch instruction is considered UB if it has `undef`
// condition.
// Skip instructions that are already saved.
if (AssumedNoUBInsts.count(&I) || KnownUBInsts.count(&I))
return true;
// We know we have a branch instruction.
auto BrInst = cast<BranchInst>(&I);
// Unconditional branches are never considered UB.
if (BrInst->isUnconditional())
return true;
// Either we stopped and the appropriate action was taken,
// or we got back a simplified value to continue.
Optional<Value *> SimplifiedCond =
stopOnUndefOrAssumed(A, BrInst->getCondition(), BrInst);
if (!SimplifiedCond.hasValue())
return true;
AssumedNoUBInsts.insert(&I);
return true;
};
A.checkForAllInstructions(InspectMemAccessInstForUB, *this,
{Instruction::Load, Instruction::Store,
Instruction::AtomicCmpXchg,
Instruction::AtomicRMW});
A.checkForAllInstructions(InspectBrInstForUB, *this, {Instruction::Br});
if (NoUBPrevSize != AssumedNoUBInsts.size() ||
UBPrevSize != KnownUBInsts.size())
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
bool isKnownToCauseUB(Instruction *I) const override {
return KnownUBInsts.count(I);
}
bool isAssumedToCauseUB(Instruction *I) const override {
// In simple words, if an instruction is not in the assumed to _not_
// cause UB, then it is assumed UB (that includes those
// in the KnownUBInsts set). The rest is boilerplate
// is to ensure that it is one of the instructions we test
// for UB.
switch (I->getOpcode()) {
case Instruction::Load:
case Instruction::Store:
case Instruction::AtomicCmpXchg:
case Instruction::AtomicRMW:
return !AssumedNoUBInsts.count(I);
case Instruction::Br: {
auto BrInst = cast<BranchInst>(I);
if (BrInst->isUnconditional())
return false;
return !AssumedNoUBInsts.count(I);
} break;
default:
return false;
}
return false;
}
ChangeStatus manifest(Attributor &A) override {
if (KnownUBInsts.empty())
return ChangeStatus::UNCHANGED;
for (Instruction *I : KnownUBInsts)
A.changeToUnreachableAfterManifest(I);
return ChangeStatus::CHANGED;
}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "undefined-behavior" : "no-ub";
}
/// Note: The correctness of this analysis depends on the fact that the
/// following 2 sets will stop changing after some point.
/// "Change" here means that their size changes.
/// The size of each set is monotonically increasing
/// (we only add items to them) and it is upper bounded by the number of
/// instructions in the processed function (we can never save more
/// elements in either set than this number). Hence, at some point,
/// they will stop increasing.
/// Consequently, at some point, both sets will have stopped
/// changing, effectively making the analysis reach a fixpoint.
/// Note: These 2 sets are disjoint and an instruction can be considered
/// one of 3 things:
/// 1) Known to cause UB (AAUndefinedBehavior could prove it) and put it in
/// the KnownUBInsts set.
/// 2) Assumed to cause UB (in every updateImpl, AAUndefinedBehavior
/// has a reason to assume it).
/// 3) Assumed to not cause UB. very other instruction - AAUndefinedBehavior
/// could not find a reason to assume or prove that it can cause UB,
/// hence it assumes it doesn't. We have a set for these instructions
/// so that we don't reprocess them in every update.
/// Note however that instructions in this set may cause UB.
protected:
/// A set of all live instructions _known_ to cause UB.
SmallPtrSet<Instruction *, 8> KnownUBInsts;
private:
/// A set of all the (live) instructions that are assumed to _not_ cause UB.
SmallPtrSet<Instruction *, 8> AssumedNoUBInsts;
// Should be called on updates in which if we're processing an instruction
// \p I that depends on a value \p V, one of the following has to happen:
// - If the value is assumed, then stop.
// - If the value is known but undef, then consider it UB.
// - Otherwise, do specific processing with the simplified value.
// We return None in the first 2 cases to signify that an appropriate
// action was taken and the caller should stop.
// Otherwise, we return the simplified value that the caller should
// use for specific processing.
Optional<Value *> stopOnUndefOrAssumed(Attributor &A, const Value *V,
Instruction *I) {
const auto &ValueSimplifyAA =
A.getAAFor<AAValueSimplify>(*this, IRPosition::value(*V));
Optional<Value *> SimplifiedV =
ValueSimplifyAA.getAssumedSimplifiedValue(A);
if (!ValueSimplifyAA.isKnown()) {
// Don't depend on assumed values.
return llvm::None;
}
if (!SimplifiedV.hasValue()) {
// If it is known (which we tested above) but it doesn't have a value,
// then we can assume `undef` and hence the instruction is UB.
KnownUBInsts.insert(I);
return llvm::None;
}
Value *Val = SimplifiedV.getValue();
if (isa<UndefValue>(Val)) {
KnownUBInsts.insert(I);
return llvm::None;
}
return Val;
}
};
struct AAUndefinedBehaviorFunction final : AAUndefinedBehaviorImpl {
AAUndefinedBehaviorFunction(const IRPosition &IRP)
: AAUndefinedBehaviorImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECL(UndefinedBehaviorInstruction, Instruction,
"Number of instructions known to have UB");
BUILD_STAT_NAME(UndefinedBehaviorInstruction, Instruction) +=
KnownUBInsts.size();
}
};
/// ------------------------ Will-Return Attributes ----------------------------
// Helper function that checks whether a function has any cycle.
// TODO: Replace with more efficent code
static bool containsCycle(Function &F) {
SmallPtrSet<BasicBlock *, 32> Visited;
// Traverse BB by dfs and check whether successor is already visited.
for (BasicBlock *BB : depth_first(&F)) {
Visited.insert(BB);
for (auto *SuccBB : successors(BB)) {
if (Visited.count(SuccBB))
return true;
}
}
return false;
}
// Helper function that checks the function have a loop which might become an
// endless loop
// FIXME: Any cycle is regarded as endless loop for now.
// We have to allow some patterns.
static bool containsPossiblyEndlessLoop(Function *F) {
return !F || !F->hasExactDefinition() || containsCycle(*F);
}
struct AAWillReturnImpl : public AAWillReturn {
AAWillReturnImpl(const IRPosition &IRP) : AAWillReturn(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAWillReturn::initialize(A);
Function *F = getAssociatedFunction();
if (containsPossiblyEndlessLoop(F))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto CheckForWillReturn = [&](Instruction &I) {
IRPosition IPos = IRPosition::callsite_function(ImmutableCallSite(&I));
const auto &WillReturnAA = A.getAAFor<AAWillReturn>(*this, IPos);
if (WillReturnAA.isKnownWillReturn())
return true;
if (!WillReturnAA.isAssumedWillReturn())
return false;
const auto &NoRecurseAA = A.getAAFor<AANoRecurse>(*this, IPos);
return NoRecurseAA.isAssumedNoRecurse();
};
if (!A.checkForAllCallLikeInstructions(CheckForWillReturn, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::getAsStr()
const std::string getAsStr() const override {
return getAssumed() ? "willreturn" : "may-noreturn";
}
};
struct AAWillReturnFunction final : AAWillReturnImpl {
AAWillReturnFunction(const IRPosition &IRP) : AAWillReturnImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(willreturn) }
};
/// WillReturn attribute deduction for a call sites.
struct AAWillReturnCallSite final : AAWillReturnImpl {
AAWillReturnCallSite(const IRPosition &IRP) : AAWillReturnImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAWillReturnImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AAWillReturn>(*this, FnPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AAWillReturn::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(willreturn); }
};
/// -------------------AAReachability Attribute--------------------------
struct AAReachabilityImpl : AAReachability {
AAReachabilityImpl(const IRPosition &IRP) : AAReachability(IRP) {}
const std::string getAsStr() const override {
// TODO: Return the number of reachable queries.
return "reachable";
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override { indicatePessimisticFixpoint(); }
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
};
struct AAReachabilityFunction final : public AAReachabilityImpl {
AAReachabilityFunction(const IRPosition &IRP) : AAReachabilityImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(reachable); }
};
/// ------------------------ NoAlias Argument Attribute ------------------------
struct AANoAliasImpl : AANoAlias {
AANoAliasImpl(const IRPosition &IRP) : AANoAlias(IRP) {}
const std::string getAsStr() const override {
return getAssumed() ? "noalias" : "may-alias";
}
};
/// NoAlias attribute for a floating value.
struct AANoAliasFloating final : AANoAliasImpl {
AANoAliasFloating(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoAliasImpl::initialize(A);
Value &Val = getAssociatedValue();
if (isa<AllocaInst>(Val))
indicateOptimisticFixpoint();
if (isa<ConstantPointerNull>(Val) &&
Val.getType()->getPointerAddressSpace() == 0)
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Implement this.
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(noalias)
}
};
/// NoAlias attribute for an argument.
struct AANoAliasArgument final
: AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl> {
using Base = AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl>;
AANoAliasArgument(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::update(...).
ChangeStatus updateImpl(Attributor &A) override {
// We have to make sure no-alias on the argument does not break
// synchronization when this is a callback argument, see also [1] below.
// If synchronization cannot be affected, we delegate to the base updateImpl
// function, otherwise we give up for now.
// If the function is no-sync, no-alias cannot break synchronization.
const auto &NoSyncAA = A.getAAFor<AANoSync>(
*this, IRPosition::function_scope(getIRPosition()));
if (NoSyncAA.isAssumedNoSync())
return Base::updateImpl(A);
// If the argument is read-only, no-alias cannot break synchronization.
const auto &MemBehaviorAA =
A.getAAFor<AAMemoryBehavior>(*this, getIRPosition());
if (MemBehaviorAA.isAssumedReadOnly())
return Base::updateImpl(A);
// If the argument is never passed through callbacks, no-alias cannot break
// synchronization.
if (A.checkForAllCallSites(
[](AbstractCallSite ACS) { return !ACS.isCallbackCall(); }, *this,
true))
return Base::updateImpl(A);
// TODO: add no-alias but make sure it doesn't break synchronization by
// introducing fake uses. See:
// [1] Compiler Optimizations for OpenMP, J. Doerfert and H. Finkel,
// International Workshop on OpenMP 2018,
// http://compilers.cs.uni-saarland.de/people/doerfert/par_opt18.pdf
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(noalias) }
};
struct AANoAliasCallSiteArgument final : AANoAliasImpl {
AANoAliasCallSiteArgument(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// See callsite argument attribute and callee argument attribute.
ImmutableCallSite ICS(&getAnchorValue());
if (ICS.paramHasAttr(getArgNo(), Attribute::NoAlias))
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// We can deduce "noalias" if the following conditions hold.
// (i) Associated value is assumed to be noalias in the definition.
// (ii) Associated value is assumed to be no-capture in all the uses
// possibly executed before this callsite.
// (iii) There is no other pointer argument which could alias with the
// value.
const Value &V = getAssociatedValue();
const IRPosition IRP = IRPosition::value(V);
// (i) Check whether noalias holds in the definition.
auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, IRP);
LLVM_DEBUG(dbgs() << "[Attributor][AANoAliasCSArg] check definition: " << V
<< " :: " << NoAliasAA << "\n");
if (!NoAliasAA.isAssumedNoAlias())
return indicatePessimisticFixpoint();
LLVM_DEBUG(dbgs() << "[Attributor][AANoAliasCSArg] " << V
<< " is assumed NoAlias in the definition\n");
// (ii) Check whether the value is captured in the scope using AANoCapture.
// FIXME: This is conservative though, it is better to look at CFG and
// check only uses possibly executed before this callsite.
auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, IRP);
if (!NoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
LLVM_DEBUG(
dbgs() << "[Attributor][AANoAliasCSArg] " << V
<< " cannot be noalias as it is potentially captured\n");
return indicatePessimisticFixpoint();
}
// (iii) Check there is no other pointer argument which could alias with the
// value.
// TODO: AbstractCallSite
ImmutableCallSite ICS(&getAnchorValue());
for (unsigned i = 0; i < ICS.getNumArgOperands(); i++) {
if (getArgNo() == (int)i)
continue;
const Value *ArgOp = ICS.getArgOperand(i);
if (!ArgOp->getType()->isPointerTy())
continue;
if (const Function *F = getAnchorScope()) {
if (AAResults *AAR = A.getInfoCache().getAAResultsForFunction(*F)) {
bool IsAliasing = !AAR->isNoAlias(&getAssociatedValue(), ArgOp);
LLVM_DEBUG(dbgs()
<< "[Attributor][NoAliasCSArg] Check alias between "
"callsite arguments "
<< AAR->isNoAlias(&getAssociatedValue(), ArgOp) << " "
<< getAssociatedValue() << " " << *ArgOp << " => "
<< (IsAliasing ? "" : "no-") << "alias \n");
if (!IsAliasing)
continue;
}
}
return indicatePessimisticFixpoint();
}
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(noalias) }
};
/// NoAlias attribute for function return value.
struct AANoAliasReturned final : AANoAliasImpl {
AANoAliasReturned(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
virtual ChangeStatus updateImpl(Attributor &A) override {
auto CheckReturnValue = [&](Value &RV) -> bool {
if (Constant *C = dyn_cast<Constant>(&RV))
if (C->isNullValue() || isa<UndefValue>(C))
return true;
/// For now, we can only deduce noalias if we have call sites.
/// FIXME: add more support.
ImmutableCallSite ICS(&RV);
if (!ICS)
return false;
const IRPosition &RVPos = IRPosition::value(RV);
const auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, RVPos);
if (!NoAliasAA.isAssumedNoAlias())
return false;
const auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, RVPos);
return NoCaptureAA.isAssumedNoCaptureMaybeReturned();
};
if (!A.checkForAllReturnedValues(CheckReturnValue, *this))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(noalias) }
};
/// NoAlias attribute deduction for a call site return value.
struct AANoAliasCallSiteReturned final : AANoAliasImpl {
AANoAliasCallSiteReturned(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoAliasImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::returned(*F);
auto &FnAA = A.getAAFor<AANoAlias>(*this, FnPos);
return clampStateAndIndicateChange(
getState(), static_cast<const AANoAlias::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(noalias); }
};
/// -------------------AAIsDead Function Attribute-----------------------
struct AAIsDeadValueImpl : public AAIsDead {
AAIsDeadValueImpl(const IRPosition &IRP) : AAIsDead(IRP) {}
/// See AAIsDead::isAssumedDead().
bool isAssumedDead() const override { return getAssumed(); }
/// See AAIsDead::isAssumedDead(BasicBlock *).
bool isAssumedDead(const BasicBlock *BB) const override { return false; }
/// See AAIsDead::isKnownDead(BasicBlock *).
bool isKnownDead(const BasicBlock *BB) const override { return false; }
/// See AAIsDead::isAssumedDead(Instruction *I).
bool isAssumedDead(const Instruction *I) const override {
return I == getCtxI() && isAssumedDead();
}
/// See AAIsDead::isKnownDead(Instruction *I).
bool isKnownDead(const Instruction *I) const override {
return I == getCtxI() && getKnown();
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return isAssumedDead() ? "assumed-dead" : "assumed-live";
}
};
struct AAIsDeadFloating : public AAIsDeadValueImpl {
AAIsDeadFloating(const IRPosition &IRP) : AAIsDeadValueImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (Instruction *I = dyn_cast<Instruction>(&getAssociatedValue()))
if (!wouldInstructionBeTriviallyDead(I))
indicatePessimisticFixpoint();
if (isa<UndefValue>(getAssociatedValue()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto UsePred = [&](const Use &U, bool &Follow) {
Instruction *UserI = cast<Instruction>(U.getUser());
if (CallSite CS = CallSite(UserI)) {
if (!CS.isArgOperand(&U))
return false;
const IRPosition &CSArgPos =
IRPosition::callsite_argument(CS, CS.getArgumentNo(&U));
const auto &CSArgIsDead = A.getAAFor<AAIsDead>(*this, CSArgPos);
return CSArgIsDead.isAssumedDead();
}
if (ReturnInst *RI = dyn_cast<ReturnInst>(UserI)) {
const IRPosition &RetPos = IRPosition::returned(*RI->getFunction());
const auto &RetIsDeadAA = A.getAAFor<AAIsDead>(*this, RetPos);
return RetIsDeadAA.isAssumedDead();
}
Follow = true;
return wouldInstructionBeTriviallyDead(UserI);
};
if (!A.checkForAllUses(UsePred, *this, getAssociatedValue()))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
Value &V = getAssociatedValue();
if (auto *I = dyn_cast<Instruction>(&V))
if (wouldInstructionBeTriviallyDead(I)) {
A.deleteAfterManifest(*I);
return ChangeStatus::CHANGED;
}
if (V.use_empty())
return ChangeStatus::UNCHANGED;
UndefValue &UV = *UndefValue::get(V.getType());
bool AnyChange = A.changeValueAfterManifest(V, UV);
return AnyChange ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(IsDead)
}
};
struct AAIsDeadArgument : public AAIsDeadFloating {
AAIsDeadArgument(const IRPosition &IRP) : AAIsDeadFloating(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (!getAssociatedFunction()->hasExactDefinition())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = AAIsDeadFloating::manifest(A);
Argument &Arg = *getAssociatedArgument();
if (Arg.getParent()->hasLocalLinkage())
if (A.registerFunctionSignatureRewrite(
Arg, /* ReplacementTypes */ {},
Attributor::ArgumentReplacementInfo::CalleeRepairCBTy{},
Attributor::ArgumentReplacementInfo::ACSRepairCBTy{}))
return ChangeStatus::CHANGED;
return Changed;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(IsDead) }
};
struct AAIsDeadCallSiteArgument : public AAIsDeadValueImpl {
AAIsDeadCallSiteArgument(const IRPosition &IRP) : AAIsDeadValueImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (isa<UndefValue>(getAssociatedValue()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AAIsDead>(*this, ArgPos);
return clampStateAndIndicateChange(
getState(), static_cast<const AAIsDead::StateType &>(ArgAA.getState()));
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
CallBase &CB = cast<CallBase>(getAnchorValue());
Use &U = CB.getArgOperandUse(getArgNo());
assert(!isa<UndefValue>(U.get()) &&
"Expected undef values to be filtered out!");
UndefValue &UV = *UndefValue::get(U->getType());
if (A.changeUseAfterManifest(U, UV))
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(IsDead) }
};
struct AAIsDeadReturned : public AAIsDeadValueImpl {
AAIsDeadReturned(const IRPosition &IRP) : AAIsDeadValueImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
auto PredForCallSite = [&](AbstractCallSite ACS) {
if (ACS.isCallbackCall())
return false;
const IRPosition &CSRetPos =
IRPosition::callsite_returned(ACS.getCallSite());
const auto &RetIsDeadAA = A.getAAFor<AAIsDead>(*this, CSRetPos);
return RetIsDeadAA.isAssumedDead();
};
if (!A.checkForAllCallSites(PredForCallSite, *this, true))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// TODO: Rewrite the signature to return void?
bool AnyChange = false;
UndefValue &UV = *UndefValue::get(getAssociatedFunction()->getReturnType());
auto RetInstPred = [&](Instruction &I) {
ReturnInst &RI = cast<ReturnInst>(I);
if (!isa<UndefValue>(RI.getReturnValue()))
AnyChange |= A.changeUseAfterManifest(RI.getOperandUse(0), UV);
return true;
};
A.checkForAllInstructions(RetInstPred, *this, {Instruction::Ret});
return AnyChange ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(IsDead) }
};
struct AAIsDeadCallSiteReturned : public AAIsDeadFloating {
AAIsDeadCallSiteReturned(const IRPosition &IRP) : AAIsDeadFloating(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSRET_ATTR(IsDead) }
};
struct AAIsDeadFunction : public AAIsDead {
AAIsDeadFunction(const IRPosition &IRP) : AAIsDead(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
const Function *F = getAssociatedFunction();
if (F && !F->isDeclaration()) {
ToBeExploredFrom.insert(&F->getEntryBlock().front());
assumeLive(A, F->getEntryBlock());
}
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return "Live[#BB " + std::to_string(AssumedLiveBlocks.size()) + "/" +
std::to_string(getAssociatedFunction()->size()) + "][#TBEP " +
std::to_string(ToBeExploredFrom.size()) + "][#KDE " +
std::to_string(KnownDeadEnds.size()) + "]";
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
assert(getState().isValidState() &&
"Attempted to manifest an invalid state!");
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
Function &F = *getAssociatedFunction();
if (AssumedLiveBlocks.empty()) {
A.deleteAfterManifest(F);
return ChangeStatus::CHANGED;
}
// Flag to determine if we can change an invoke to a call assuming the
// callee is nounwind. This is not possible if the personality of the
// function allows to catch asynchronous exceptions.
bool Invoke2CallAllowed = !mayCatchAsynchronousExceptions(F);
KnownDeadEnds.set_union(ToBeExploredFrom);
for (const Instruction *DeadEndI : KnownDeadEnds) {
auto *CB = dyn_cast<CallBase>(DeadEndI);
if (!CB)
continue;
const auto &NoReturnAA =
A.getAAFor<AANoReturn>(*this, IRPosition::callsite_function(*CB));
bool MayReturn = !NoReturnAA.isAssumedNoReturn();
if (MayReturn && (!Invoke2CallAllowed || !isa<InvokeInst>(CB)))
continue;
if (auto *II = dyn_cast<InvokeInst>(DeadEndI))
A.registerInvokeWithDeadSuccessor(const_cast<InvokeInst &>(*II));
else
A.changeToUnreachableAfterManifest(
const_cast<Instruction *>(DeadEndI->getNextNode()));
HasChanged = ChangeStatus::CHANGED;
}
for (BasicBlock &BB : F)
if (!AssumedLiveBlocks.count(&BB))
A.deleteAfterManifest(BB);
return HasChanged;
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
/// Returns true if the function is assumed dead.
bool isAssumedDead() const override { return false; }
/// See AAIsDead::isAssumedDead(BasicBlock *).
bool isAssumedDead(const BasicBlock *BB) const override {
assert(BB->getParent() == getAssociatedFunction() &&
"BB must be in the same anchor scope function.");
if (!getAssumed())
return false;
return !AssumedLiveBlocks.count(BB);
}
/// See AAIsDead::isKnownDead(BasicBlock *).
bool isKnownDead(const BasicBlock *BB) const override {
return getKnown() && isAssumedDead(BB);
}
/// See AAIsDead::isAssumed(Instruction *I).
bool isAssumedDead(const Instruction *I) const override {
assert(I->getParent()->getParent() == getAssociatedFunction() &&
"Instruction must be in the same anchor scope function.");
if (!getAssumed())
return false;
// If it is not in AssumedLiveBlocks then it for sure dead.
// Otherwise, it can still be after noreturn call in a live block.
if (!AssumedLiveBlocks.count(I->getParent()))
return true;
// If it is not after a liveness barrier it is live.
const Instruction *PrevI = I->getPrevNode();
while (PrevI) {
if (KnownDeadEnds.count(PrevI) || ToBeExploredFrom.count(PrevI))
return true;
PrevI = PrevI->getPrevNode();
}
return false;
}
/// See AAIsDead::isKnownDead(Instruction *I).
bool isKnownDead(const Instruction *I) const override {
return getKnown() && isAssumedDead(I);
}
/// Determine if \p F might catch asynchronous exceptions.
static bool mayCatchAsynchronousExceptions(const Function &F) {
return F.hasPersonalityFn() && !canSimplifyInvokeNoUnwind(&F);
}
/// Assume \p BB is (partially) live now and indicate to the Attributor \p A
/// that internal function called from \p BB should now be looked at.
bool assumeLive(Attributor &A, const BasicBlock &BB) {
if (!AssumedLiveBlocks.insert(&BB).second)
return false;
// We assume that all of BB is (probably) live now and if there are calls to
// internal functions we will assume that those are now live as well. This
// is a performance optimization for blocks with calls to a lot of internal
// functions. It can however cause dead functions to be treated as live.
for (const Instruction &I : BB)
if (ImmutableCallSite ICS = ImmutableCallSite(&I))
if (const Function *F = ICS.getCalledFunction())
if (F->hasLocalLinkage())
A.markLiveInternalFunction(*F);
return true;
}
/// Collection of instructions that need to be explored again, e.g., we
/// did assume they do not transfer control to (one of their) successors.
SmallSetVector<const Instruction *, 8> ToBeExploredFrom;
/// Collection of instructions that are known to not transfer control.
SmallSetVector<const Instruction *, 8> KnownDeadEnds;
/// Collection of all assumed live BasicBlocks.
DenseSet<const BasicBlock *> AssumedLiveBlocks;
};
static bool
identifyAliveSuccessors(Attributor &A, const CallBase &CB,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
const IRPosition &IPos = IRPosition::callsite_function(CB);
const auto &NoReturnAA = A.getAAFor<AANoReturn>(AA, IPos);
if (NoReturnAA.isAssumedNoReturn())
return !NoReturnAA.isKnownNoReturn();
if (CB.isTerminator())
AliveSuccessors.push_back(&CB.getSuccessor(0)->front());
else
AliveSuccessors.push_back(CB.getNextNode());
return false;
}
static bool
identifyAliveSuccessors(Attributor &A, const InvokeInst &II,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation =
identifyAliveSuccessors(A, cast<CallBase>(II), AA, AliveSuccessors);
// First, determine if we can change an invoke to a call assuming the
// callee is nounwind. This is not possible if the personality of the
// function allows to catch asynchronous exceptions.
if (AAIsDeadFunction::mayCatchAsynchronousExceptions(*II.getFunction())) {
AliveSuccessors.push_back(&II.getUnwindDest()->front());
} else {
const IRPosition &IPos = IRPosition::callsite_function(II);
const auto &AANoUnw = A.getAAFor<AANoUnwind>(AA, IPos);
if (AANoUnw.isAssumedNoUnwind()) {
UsedAssumedInformation |= !AANoUnw.isKnownNoUnwind();
} else {
AliveSuccessors.push_back(&II.getUnwindDest()->front());
}
}
return UsedAssumedInformation;
}
static Optional<ConstantInt *>
getAssumedConstant(Attributor &A, const Value &V, AbstractAttribute &AA,
bool &UsedAssumedInformation) {
const auto &ValueSimplifyAA =
A.getAAFor<AAValueSimplify>(AA, IRPosition::value(V));
Optional<Value *> SimplifiedV = ValueSimplifyAA.getAssumedSimplifiedValue(A);
UsedAssumedInformation |= !ValueSimplifyAA.isKnown();
if (!SimplifiedV.hasValue())
return llvm::None;
if (isa_and_nonnull<UndefValue>(SimplifiedV.getValue()))
return llvm::None;
return dyn_cast_or_null<ConstantInt>(SimplifiedV.getValue());
}
static bool
identifyAliveSuccessors(Attributor &A, const BranchInst &BI,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation = false;
if (BI.getNumSuccessors() == 1) {
AliveSuccessors.push_back(&BI.getSuccessor(0)->front());
} else {
Optional<ConstantInt *> CI =
getAssumedConstant(A, *BI.getCondition(), AA, UsedAssumedInformation);
if (!CI.hasValue()) {
// No value yet, assume both edges are dead.
} else if (CI.getValue()) {
const BasicBlock *SuccBB =
BI.getSuccessor(1 - CI.getValue()->getZExtValue());
AliveSuccessors.push_back(&SuccBB->front());
} else {
AliveSuccessors.push_back(&BI.getSuccessor(0)->front());
AliveSuccessors.push_back(&BI.getSuccessor(1)->front());
UsedAssumedInformation = false;
}
}
return UsedAssumedInformation;
}
static bool
identifyAliveSuccessors(Attributor &A, const SwitchInst &SI,
AbstractAttribute &AA,
SmallVectorImpl<const Instruction *> &AliveSuccessors) {
bool UsedAssumedInformation = false;
Optional<ConstantInt *> CI =
getAssumedConstant(A, *SI.getCondition(), AA, UsedAssumedInformation);
if (!CI.hasValue()) {
// No value yet, assume all edges are dead.
} else if (CI.getValue()) {
for (auto &CaseIt : SI.cases()) {
if (CaseIt.getCaseValue() == CI.getValue()) {
AliveSuccessors.push_back(&CaseIt.getCaseSuccessor()->front());
return UsedAssumedInformation;
}
}
AliveSuccessors.push_back(&SI.getDefaultDest()->front());
return UsedAssumedInformation;
} else {
for (const BasicBlock *SuccBB : successors(SI.getParent()))
AliveSuccessors.push_back(&SuccBB->front());
}
return UsedAssumedInformation;
}
ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
ChangeStatus Change = ChangeStatus::UNCHANGED;
LLVM_DEBUG(dbgs() << "[AAIsDead] Live [" << AssumedLiveBlocks.size() << "/"
<< getAssociatedFunction()->size() << "] BBs and "
<< ToBeExploredFrom.size() << " exploration points and "
<< KnownDeadEnds.size() << " known dead ends\n");
// Copy and clear the list of instructions we need to explore from. It is
// refilled with instructions the next update has to look at.
SmallVector<const Instruction *, 8> Worklist(ToBeExploredFrom.begin(),
ToBeExploredFrom.end());
decltype(ToBeExploredFrom) NewToBeExploredFrom;
SmallVector<const Instruction *, 8> AliveSuccessors;
while (!Worklist.empty()) {
const Instruction *I = Worklist.pop_back_val();
LLVM_DEBUG(dbgs() << "[AAIsDead] Exploration inst: " << *I << "\n");
AliveSuccessors.clear();
bool UsedAssumedInformation = false;
switch (I->getOpcode()) {
// TODO: look for (assumed) UB to backwards propagate "deadness".
default:
if (I->isTerminator()) {
for (const BasicBlock *SuccBB : successors(I->getParent()))
AliveSuccessors.push_back(&SuccBB->front());
} else {
AliveSuccessors.push_back(I->getNextNode());
}
break;
case Instruction::Call:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<CallInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Invoke:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<InvokeInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Br:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<BranchInst>(*I),
*this, AliveSuccessors);
break;
case Instruction::Switch:
UsedAssumedInformation = identifyAliveSuccessors(A, cast<SwitchInst>(*I),
*this, AliveSuccessors);
break;
}
if (UsedAssumedInformation) {
NewToBeExploredFrom.insert(I);
} else {
Change = ChangeStatus::CHANGED;
if (AliveSuccessors.empty() ||
(I->isTerminator() && AliveSuccessors.size() < I->getNumSuccessors()))
KnownDeadEnds.insert(I);
}
LLVM_DEBUG(dbgs() << "[AAIsDead] #AliveSuccessors: "
<< AliveSuccessors.size() << " UsedAssumedInformation: "
<< UsedAssumedInformation << "\n");
for (const Instruction *AliveSuccessor : AliveSuccessors) {
if (!I->isTerminator()) {
assert(AliveSuccessors.size() == 1 &&
"Non-terminator expected to have a single successor!");
Worklist.push_back(AliveSuccessor);
} else {
if (assumeLive(A, *AliveSuccessor->getParent()))
Worklist.push_back(AliveSuccessor);
}
}
}
ToBeExploredFrom = std::move(NewToBeExploredFrom);
// If we know everything is live there is no need to query for liveness.
// Instead, indicating a pessimistic fixpoint will cause the state to be
// "invalid" and all queries to be answered conservatively without lookups.
// To be in this state we have to (1) finished the exploration and (3) not
// discovered any non-trivial dead end and (2) not ruled unreachable code
// dead.
if (ToBeExploredFrom.empty() &&
getAssociatedFunction()->size() == AssumedLiveBlocks.size() &&
llvm::all_of(KnownDeadEnds, [](const Instruction *DeadEndI) {
return DeadEndI->isTerminator() && DeadEndI->getNumSuccessors() == 0;
}))
return indicatePessimisticFixpoint();
return Change;
}
/// Liveness information for a call sites.
struct AAIsDeadCallSite final : AAIsDeadFunction {
AAIsDeadCallSite(const IRPosition &IRP) : AAIsDeadFunction(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites instead of
// redirecting requests to the callee.
llvm_unreachable("Abstract attributes for liveness are not "
"supported for call sites yet!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
return indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// -------------------- Dereferenceable Argument Attribute --------------------
template <>
ChangeStatus clampStateAndIndicateChange<DerefState>(DerefState &S,
const DerefState &R) {
ChangeStatus CS0 =
clampStateAndIndicateChange(S.DerefBytesState, R.DerefBytesState);
ChangeStatus CS1 = clampStateAndIndicateChange(S.GlobalState, R.GlobalState);
return CS0 | CS1;
}
struct AADereferenceableImpl : AADereferenceable {
AADereferenceableImpl(const IRPosition &IRP) : AADereferenceable(IRP) {}
using StateType = DerefState;
void initialize(Attributor &A) override {
SmallVector<Attribute, 4> Attrs;
getAttrs({Attribute::Dereferenceable, Attribute::DereferenceableOrNull},
Attrs);
for (const Attribute &Attr : Attrs)
takeKnownDerefBytesMaximum(Attr.getValueAsInt());
NonNullAA = &A.getAAFor<AANonNull>(*this, getIRPosition());
const IRPosition &IRP = this->getIRPosition();
bool IsFnInterface = IRP.isFnInterfaceKind();
const Function *FnScope = IRP.getAnchorScope();
if (IsFnInterface && (!FnScope || !FnScope->hasExactDefinition()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::getState()
/// {
StateType &getState() override { return *this; }
const StateType &getState() const override { return *this; }
/// }
/// Helper function for collecting accessed bytes in must-be-executed-context
void addAccessedBytesForUse(Attributor &A, const Use *U,
const Instruction *I) {
const Value *UseV = U->get();
if (!UseV->getType()->isPointerTy())
return;
Type *PtrTy = UseV->getType();
const DataLayout &DL = A.getDataLayout();
int64_t Offset;
if (const Value *Base = getBasePointerOfAccessPointerOperand(
I, Offset, DL, /*AllowNonInbounds*/ true)) {
if (Base == &getAssociatedValue() &&
Attributor::getPointerOperand(I, /* AllowVolatile */ false) == UseV) {
uint64_t Size = DL.getTypeStoreSize(PtrTy->getPointerElementType());
addAccessedBytes(Offset, Size);
}
}
return;
}
/// See AAFromMustBeExecutedContext
bool followUse(Attributor &A, const Use *U, const Instruction *I) {
bool IsNonNull = false;
bool TrackUse = false;
int64_t DerefBytes = getKnownNonNullAndDerefBytesForUse(
A, *this, getAssociatedValue(), U, I, IsNonNull, TrackUse);
addAccessedBytesForUse(A, U, I);
takeKnownDerefBytesMaximum(DerefBytes);
return TrackUse;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Change = AADereferenceable::manifest(A);
if (isAssumedNonNull() && hasAttr(Attribute::DereferenceableOrNull)) {
removeAttrs({Attribute::DereferenceableOrNull});
return ChangeStatus::CHANGED;
}
return Change;
}
void getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
// TODO: Add *_globally support
if (isAssumedNonNull())
Attrs.emplace_back(Attribute::getWithDereferenceableBytes(
Ctx, getAssumedDereferenceableBytes()));
else
Attrs.emplace_back(Attribute::getWithDereferenceableOrNullBytes(
Ctx, getAssumedDereferenceableBytes()));
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
if (!getAssumedDereferenceableBytes())
return "unknown-dereferenceable";
return std::string("dereferenceable") +
(isAssumedNonNull() ? "" : "_or_null") +
(isAssumedGlobal() ? "_globally" : "") + "<" +
std::to_string(getKnownDereferenceableBytes()) + "-" +
std::to_string(getAssumedDereferenceableBytes()) + ">";
}
};
/// Dereferenceable attribute for a floating value.
struct AADereferenceableFloating
: AAFromMustBeExecutedContext<AADereferenceable, AADereferenceableImpl> {
using Base =
AAFromMustBeExecutedContext<AADereferenceable, AADereferenceableImpl>;
AADereferenceableFloating(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus Change = Base::updateImpl(A);
const DataLayout &DL = A.getDataLayout();
auto VisitValueCB = [&](Value &V, DerefState &T, bool Stripped) -> bool {
unsigned IdxWidth =
DL.getIndexSizeInBits(V.getType()->getPointerAddressSpace());
APInt Offset(IdxWidth, 0);
const Value *Base =
V.stripAndAccumulateInBoundsConstantOffsets(DL, Offset);
const auto &AA =
A.getAAFor<AADereferenceable>(*this, IRPosition::value(*Base));
int64_t DerefBytes = 0;
if (!Stripped && this == &AA) {
// Use IR information if we did not strip anything.
// TODO: track globally.
bool CanBeNull;
DerefBytes = Base->getPointerDereferenceableBytes(DL, CanBeNull);
T.GlobalState.indicatePessimisticFixpoint();
} else {
const DerefState &DS = static_cast<const DerefState &>(AA.getState());
DerefBytes = DS.DerefBytesState.getAssumed();
T.GlobalState &= DS.GlobalState;
}
// TODO: Use `AAConstantRange` to infer dereferenceable bytes.
// For now we do not try to "increase" dereferenceability due to negative
// indices as we first have to come up with code to deal with loops and
// for overflows of the dereferenceable bytes.
int64_t OffsetSExt = Offset.getSExtValue();
if (OffsetSExt < 0)
OffsetSExt = 0;
T.takeAssumedDerefBytesMinimum(
std::max(int64_t(0), DerefBytes - OffsetSExt));
if (this == &AA) {
if (!Stripped) {
// If nothing was stripped IR information is all we got.
T.takeKnownDerefBytesMaximum(
std::max(int64_t(0), DerefBytes - OffsetSExt));
T.indicatePessimisticFixpoint();
} else if (OffsetSExt > 0) {
// If something was stripped but there is circular reasoning we look
// for the offset. If it is positive we basically decrease the
// dereferenceable bytes in a circluar loop now, which will simply
// drive them down to the known value in a very slow way which we
// can accelerate.
T.indicatePessimisticFixpoint();
}
}
return T.isValidState();
};
DerefState T;
if (!genericValueTraversal<AADereferenceable, DerefState>(
A, getIRPosition(), *this, T, VisitValueCB))
return indicatePessimisticFixpoint();
return Change | clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for a return value.
struct AADereferenceableReturned final
: AAReturnedFromReturnedValues<AADereferenceable, AADereferenceableImpl,
DerefState> {
AADereferenceableReturned(const IRPosition &IRP)
: AAReturnedFromReturnedValues<AADereferenceable, AADereferenceableImpl,
DerefState>(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for an argument
struct AADereferenceableArgument final
: AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<
AADereferenceable, AADereferenceableImpl, DerefState> {
using Base = AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<
AADereferenceable, AADereferenceableImpl, DerefState>;
AADereferenceableArgument(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute for a call site argument.
struct AADereferenceableCallSiteArgument final : AADereferenceableFloating {
AADereferenceableCallSiteArgument(const IRPosition &IRP)
: AADereferenceableFloating(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(dereferenceable)
}
};
/// Dereferenceable attribute deduction for a call site return value.
struct AADereferenceableCallSiteReturned final
: AACallSiteReturnedFromReturnedAndMustBeExecutedContext<
AADereferenceable, AADereferenceableImpl> {
using Base = AACallSiteReturnedFromReturnedAndMustBeExecutedContext<
AADereferenceable, AADereferenceableImpl>;
AADereferenceableCallSiteReturned(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CS_ATTR(dereferenceable);
}
};
// ------------------------ Align Argument Attribute ------------------------
static unsigned int getKnownAlignForUse(Attributor &A,
AbstractAttribute &QueryingAA,
Value &AssociatedValue, const Use *U,
const Instruction *I, bool &TrackUse) {
// We need to follow common pointer manipulation uses to the accesses they
// feed into.
if (isa<CastInst>(I)) {
// Follow all but ptr2int casts.
TrackUse = !isa<PtrToIntInst>(I);
return 0;
}
if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
if (GEP->hasAllConstantIndices()) {
TrackUse = true;
return 0;
}
}
unsigned Alignment = 0;
if (ImmutableCallSite ICS = ImmutableCallSite(I)) {
if (ICS.isBundleOperand(U) || ICS.isCallee(U))
return 0;
unsigned ArgNo = ICS.getArgumentNo(U);
IRPosition IRP = IRPosition::callsite_argument(ICS, ArgNo);
// As long as we only use known information there is no need to track
// dependences here.
auto &AlignAA = A.getAAFor<AAAlign>(QueryingAA, IRP,
/* TrackDependence */ false);
Alignment = AlignAA.getKnownAlign();
}
const Value *UseV = U->get();
if (auto *SI = dyn_cast<StoreInst>(I))
Alignment = SI->getAlignment();
else if (auto *LI = dyn_cast<LoadInst>(I))
Alignment = LI->getAlignment();
if (Alignment <= 1)
return 0;
auto &DL = A.getDataLayout();
int64_t Offset;
if (const Value *Base = GetPointerBaseWithConstantOffset(UseV, Offset, DL)) {
if (Base == &AssociatedValue) {
// BasePointerAddr + Offset = Alignment * Q for some integer Q.
// So we can say that the maximum power of two which is a divisor of
// gcd(Offset, Alignment) is an alignment.
uint32_t gcd =
greatestCommonDivisor(uint32_t(abs((int32_t)Offset)), Alignment);
Alignment = llvm::PowerOf2Floor(gcd);
}
}
return Alignment;
}
struct AAAlignImpl : AAAlign {
AAAlignImpl(const IRPosition &IRP) : AAAlign(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
SmallVector<Attribute, 4> Attrs;
getAttrs({Attribute::Alignment}, Attrs);
for (const Attribute &Attr : Attrs)
takeKnownMaximum(Attr.getValueAsInt());
if (getIRPosition().isFnInterfaceKind() &&
(!getAssociatedFunction() ||
!getAssociatedFunction()->hasExactDefinition()))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
// Check for users that allow alignment annotations.
Value &AnchorVal = getIRPosition().getAnchorValue();
for (const Use &U : AnchorVal.uses()) {
if (auto *SI = dyn_cast<StoreInst>(U.getUser())) {
if (SI->getPointerOperand() == &AnchorVal)
if (SI->getAlignment() < getAssumedAlign()) {
STATS_DECLTRACK(AAAlign, Store,
"Number of times alignment added to a store");
SI->setAlignment(Align(getAssumedAlign()));
Changed = ChangeStatus::CHANGED;
}
} else if (auto *LI = dyn_cast<LoadInst>(U.getUser())) {
if (LI->getPointerOperand() == &AnchorVal)
if (LI->getAlignment() < getAssumedAlign()) {
LI->setAlignment(Align(getAssumedAlign()));
STATS_DECLTRACK(AAAlign, Load,
"Number of times alignment added to a load");
Changed = ChangeStatus::CHANGED;
}
}
}
return AAAlign::manifest(A) | Changed;
}
// TODO: Provide a helper to determine the implied ABI alignment and check in
// the existing manifest method and a new one for AAAlignImpl that value
// to avoid making the alignment explicit if it did not improve.
/// See AbstractAttribute::getDeducedAttributes
virtual void
getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
if (getAssumedAlign() > 1)
Attrs.emplace_back(
Attribute::getWithAlignment(Ctx, Align(getAssumedAlign())));
}
/// See AAFromMustBeExecutedContext
bool followUse(Attributor &A, const Use *U, const Instruction *I) {
bool TrackUse = false;
unsigned int KnownAlign =
getKnownAlignForUse(A, *this, getAssociatedValue(), U, I, TrackUse);
takeKnownMaximum(KnownAlign);
return TrackUse;
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumedAlign() ? ("align<" + std::to_string(getKnownAlign()) +
"-" + std::to_string(getAssumedAlign()) + ">")
: "unknown-align";
}
};
/// Align attribute for a floating value.
struct AAAlignFloating : AAFromMustBeExecutedContext<AAAlign, AAAlignImpl> {
using Base = AAFromMustBeExecutedContext<AAAlign, AAAlignImpl>;
AAAlignFloating(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
Base::updateImpl(A);
const DataLayout &DL = A.getDataLayout();
auto VisitValueCB = [&](Value &V, AAAlign::StateType &T,
bool Stripped) -> bool {
const auto &AA = A.getAAFor<AAAlign>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
// Use only IR information if we did not strip anything.
const MaybeAlign PA = V.getPointerAlignment(DL);
T.takeKnownMaximum(PA ? PA->value() : 0);
T.indicatePessimisticFixpoint();
} else {
// Use abstract attribute information.
const AAAlign::StateType &DS =
static_cast<const AAAlign::StateType &>(AA.getState());
T ^= DS;
}
return T.isValidState();
};
StateType T;
if (!genericValueTraversal<AAAlign, StateType>(A, getIRPosition(), *this, T,
VisitValueCB))
return indicatePessimisticFixpoint();
// TODO: If we know we visited all incoming values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FLOATING_ATTR(align) }
};
/// Align attribute for function return value.
struct AAAlignReturned final
: AAReturnedFromReturnedValues<AAAlign, AAAlignImpl> {
AAAlignReturned(const IRPosition &IRP)
: AAReturnedFromReturnedValues<AAAlign, AAAlignImpl>(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FNRET_ATTR(aligned) }
};
/// Align attribute for function argument.
struct AAAlignArgument final
: AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<AAAlign,
AAAlignImpl> {
AAAlignArgument(const IRPosition &IRP)
: AAArgumentFromCallSiteArgumentsAndMustBeExecutedContext<AAAlign,
AAAlignImpl>(
IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(aligned) }
};
struct AAAlignCallSiteArgument final : AAAlignFloating {
AAAlignCallSiteArgument(const IRPosition &IRP) : AAAlignFloating(IRP) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
return AAAlignImpl::manifest(A);
}
/// See AbstractAttribute::updateImpl(Attributor &A).
ChangeStatus updateImpl(Attributor &A) override {
ChangeStatus Changed = AAAlignFloating::updateImpl(A);
if (Argument *Arg = getAssociatedArgument()) {
const auto &ArgAlignAA = A.getAAFor<AAAlign>(
*this, IRPosition::argument(*Arg), /* TrackDependence */ false,
DepClassTy::OPTIONAL);
takeKnownMaximum(ArgAlignAA.getKnownAlign());
}
return Changed;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CSARG_ATTR(aligned) }
};
/// Align attribute deduction for a call site return value.
struct AAAlignCallSiteReturned final
: AACallSiteReturnedFromReturnedAndMustBeExecutedContext<AAAlign,
AAAlignImpl> {
using Base =
AACallSiteReturnedFromReturnedAndMustBeExecutedContext<AAAlign,
AAAlignImpl>;
AAAlignCallSiteReturned(const IRPosition &IRP) : Base(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Base::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(align); }
};
/// ------------------ Function No-Return Attribute ----------------------------
struct AANoReturnImpl : public AANoReturn {
AANoReturnImpl(const IRPosition &IRP) : AANoReturn(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AANoReturn::initialize(A);
Function *F = getAssociatedFunction();
if (!F)
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? "noreturn" : "may-return";
}
/// See AbstractAttribute::updateImpl(Attributor &A).
virtual ChangeStatus updateImpl(Attributor &A) override {
auto CheckForNoReturn = [](Instruction &) { return false; };
if (!A.checkForAllInstructions(CheckForNoReturn, *this,
{(unsigned)Instruction::Ret}))
return indicatePessimisticFixpoint();
return ChangeStatus::UNCHANGED;
}
};
struct AANoReturnFunction final : AANoReturnImpl {
AANoReturnFunction(const IRPosition &IRP) : AANoReturnImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(noreturn) }
};
/// NoReturn attribute deduction for a call sites.
struct AANoReturnCallSite final : AANoReturnImpl {
AANoReturnCallSite(const IRPosition &IRP) : AANoReturnImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AANoReturn>(*this, FnPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AANoReturn::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(noreturn); }
};
/// ----------------------- Variable Capturing ---------------------------------
/// A class to hold the state of for no-capture attributes.
struct AANoCaptureImpl : public AANoCapture {
AANoCaptureImpl(const IRPosition &IRP) : AANoCapture(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (hasAttr(getAttrKind(), /* IgnoreSubsumingPositions */ true)) {
indicateOptimisticFixpoint();
return;
}
Function *AnchorScope = getAnchorScope();
if (isFnInterfaceKind() &&
(!AnchorScope || !AnchorScope->hasExactDefinition())) {
indicatePessimisticFixpoint();
return;
}
// You cannot "capture" null in the default address space.
if (isa<ConstantPointerNull>(getAssociatedValue()) &&
getAssociatedValue().getType()->getPointerAddressSpace() == 0) {
indicateOptimisticFixpoint();
return;
}
const Function *F = getArgNo() >= 0 ? getAssociatedFunction() : AnchorScope;
// Check what state the associated function can actually capture.
if (F)
determineFunctionCaptureCapabilities(getIRPosition(), *F, *this);
else
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// see AbstractAttribute::isAssumedNoCaptureMaybeReturned(...).
virtual void
getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
if (!isAssumedNoCaptureMaybeReturned())
return;
if (getArgNo() >= 0) {
if (isAssumedNoCapture())
Attrs.emplace_back(Attribute::get(Ctx, Attribute::NoCapture));
else if (ManifestInternal)
Attrs.emplace_back(Attribute::get(Ctx, "no-capture-maybe-returned"));
}
}
/// Set the NOT_CAPTURED_IN_MEM and NOT_CAPTURED_IN_RET bits in \p Known
/// depending on the ability of the function associated with \p IRP to capture
/// state in memory and through "returning/throwing", respectively.
static void determineFunctionCaptureCapabilities(const IRPosition &IRP,
const Function &F,
BitIntegerState &State) {
// TODO: Once we have memory behavior attributes we should use them here.
// If we know we cannot communicate or write to memory, we do not care about
// ptr2int anymore.
if (F.onlyReadsMemory() && F.doesNotThrow() &&
F.getReturnType()->isVoidTy()) {
State.addKnownBits(NO_CAPTURE);
return;
}
// A function cannot capture state in memory if it only reads memory, it can
// however return/throw state and the state might be influenced by the
// pointer value, e.g., loading from a returned pointer might reveal a bit.
if (F.onlyReadsMemory())
State.addKnownBits(NOT_CAPTURED_IN_MEM);
// A function cannot communicate state back if it does not through
// exceptions and doesn not return values.
if (F.doesNotThrow() && F.getReturnType()->isVoidTy())
State.addKnownBits(NOT_CAPTURED_IN_RET);
// Check existing "returned" attributes.
int ArgNo = IRP.getArgNo();
if (F.doesNotThrow() && ArgNo >= 0) {
for (unsigned u = 0, e = F.arg_size(); u < e; ++u)
if (F.hasParamAttribute(u, Attribute::Returned)) {
if (u == unsigned(ArgNo))
State.removeAssumedBits(NOT_CAPTURED_IN_RET);
else if (F.onlyReadsMemory())
State.addKnownBits(NO_CAPTURE);
else
State.addKnownBits(NOT_CAPTURED_IN_RET);
break;
}
}
}
/// See AbstractState::getAsStr().
const std::string getAsStr() const override {
if (isKnownNoCapture())
return "known not-captured";
if (isAssumedNoCapture())
return "assumed not-captured";
if (isKnownNoCaptureMaybeReturned())
return "known not-captured-maybe-returned";
if (isAssumedNoCaptureMaybeReturned())
return "assumed not-captured-maybe-returned";
return "assumed-captured";
}
};
/// Attributor-aware capture tracker.
struct AACaptureUseTracker final : public CaptureTracker {
/// Create a capture tracker that can lookup in-flight abstract attributes
/// through the Attributor \p A.
///
/// If a use leads to a potential capture, \p CapturedInMemory is set and the
/// search is stopped. If a use leads to a return instruction,
/// \p CommunicatedBack is set to true and \p CapturedInMemory is not changed.
/// If a use leads to a ptr2int which may capture the value,
/// \p CapturedInInteger is set. If a use is found that is currently assumed
/// "no-capture-maybe-returned", the user is added to the \p PotentialCopies
/// set. All values in \p PotentialCopies are later tracked as well. For every
/// explored use we decrement \p RemainingUsesToExplore. Once it reaches 0,
/// the search is stopped with \p CapturedInMemory and \p CapturedInInteger
/// conservatively set to true.
AACaptureUseTracker(Attributor &A, AANoCapture &NoCaptureAA,
const AAIsDead &IsDeadAA, AANoCapture::StateType &State,
SmallVectorImpl<const Value *> &PotentialCopies,
unsigned &RemainingUsesToExplore)
: A(A), NoCaptureAA(NoCaptureAA), IsDeadAA(IsDeadAA), State(State),
PotentialCopies(PotentialCopies),
RemainingUsesToExplore(RemainingUsesToExplore) {}
/// Determine if \p V maybe captured. *Also updates the state!*
bool valueMayBeCaptured(const Value *V) {
if (V->getType()->isPointerTy()) {
PointerMayBeCaptured(V, this);
} else {
State.indicatePessimisticFixpoint();
}
return State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
}
/// See CaptureTracker::tooManyUses().
void tooManyUses() override {
State.removeAssumedBits(AANoCapture::NO_CAPTURE);
}
bool isDereferenceableOrNull(Value *O, const DataLayout &DL) override {
if (CaptureTracker::isDereferenceableOrNull(O, DL))
return true;
const auto &DerefAA =
A.getAAFor<AADereferenceable>(NoCaptureAA, IRPosition::value(*O));
return DerefAA.getAssumedDereferenceableBytes();
}
/// See CaptureTracker::captured(...).
bool captured(const Use *U) override {
Instruction *UInst = cast<Instruction>(U->getUser());
LLVM_DEBUG(dbgs() << "Check use: " << *U->get() << " in " << *UInst
<< "\n");
// Because we may reuse the tracker multiple times we keep track of the
// number of explored uses ourselves as well.
if (RemainingUsesToExplore-- == 0) {
LLVM_DEBUG(dbgs() << " - too many uses to explore!\n");
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
}
// Deal with ptr2int by following uses.
if (isa<PtrToIntInst>(UInst)) {
LLVM_DEBUG(dbgs() << " - ptr2int assume the worst!\n");
return valueMayBeCaptured(UInst);
}
// Explicitly catch return instructions.
if (isa<ReturnInst>(UInst))
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ true);
// For now we only use special logic for call sites. However, the tracker
// itself knows about a lot of other non-capturing cases already.
CallSite CS(UInst);
if (!CS || !CS.isArgOperand(U))
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
unsigned ArgNo = CS.getArgumentNo(U);
const IRPosition &CSArgPos = IRPosition::callsite_argument(CS, ArgNo);
// If we have a abstract no-capture attribute for the argument we can use
// it to justify a non-capture attribute here. This allows recursion!
auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(NoCaptureAA, CSArgPos);
if (ArgNoCaptureAA.isAssumedNoCapture())
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ false);
if (ArgNoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
addPotentialCopy(CS);
return isCapturedIn(/* Memory */ false, /* Integer */ false,
/* Return */ false);
}
// Lastly, we could not find a reason no-capture can be assumed so we don't.
return isCapturedIn(/* Memory */ true, /* Integer */ true,
/* Return */ true);
}
/// Register \p CS as potential copy of the value we are checking.
void addPotentialCopy(CallSite CS) {
PotentialCopies.push_back(CS.getInstruction());
}
/// See CaptureTracker::shouldExplore(...).
bool shouldExplore(const Use *U) override {
// Check liveness.
return !IsDeadAA.isAssumedDead(cast<Instruction>(U->getUser()));
}
/// Update the state according to \p CapturedInMem, \p CapturedInInt, and
/// \p CapturedInRet, then return the appropriate value for use in the
/// CaptureTracker::captured() interface.
bool isCapturedIn(bool CapturedInMem, bool CapturedInInt,
bool CapturedInRet) {
LLVM_DEBUG(dbgs() << " - captures [Mem " << CapturedInMem << "|Int "
<< CapturedInInt << "|Ret " << CapturedInRet << "]\n");
if (CapturedInMem)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_MEM);
if (CapturedInInt)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_INT);
if (CapturedInRet)
State.removeAssumedBits(AANoCapture::NOT_CAPTURED_IN_RET);
return !State.isAssumed(AANoCapture::NO_CAPTURE_MAYBE_RETURNED);
}
private:
/// The attributor providing in-flight abstract attributes.
Attributor &A;
/// The abstract attribute currently updated.
AANoCapture &NoCaptureAA;
/// The abstract liveness state.
const AAIsDead &IsDeadAA;
/// The state currently updated.
AANoCapture::StateType &State;
/// Set of potential copies of the tracked value.
SmallVectorImpl<const Value *> &PotentialCopies;
/// Global counter to limit the number of explored uses.
unsigned &RemainingUsesToExplore;
};
ChangeStatus AANoCaptureImpl::updateImpl(Attributor &A) {
const IRPosition &IRP = getIRPosition();
const Value *V =
getArgNo() >= 0 ? IRP.getAssociatedArgument() : &IRP.getAssociatedValue();
if (!V)
return indicatePessimisticFixpoint();
const Function *F =
getArgNo() >= 0 ? IRP.getAssociatedFunction() : IRP.getAnchorScope();
assert(F && "Expected a function!");
const IRPosition &FnPos = IRPosition::function(*F);
const auto &IsDeadAA = A.getAAFor<AAIsDead>(*this, FnPos);
AANoCapture::StateType T;
// Readonly means we cannot capture through memory.
const auto &FnMemAA = A.getAAFor<AAMemoryBehavior>(*this, FnPos);
if (FnMemAA.isAssumedReadOnly()) {
T.addKnownBits(NOT_CAPTURED_IN_MEM);
if (FnMemAA.isKnownReadOnly())
addKnownBits(NOT_CAPTURED_IN_MEM);
}
// Make sure all returned values are different than the underlying value.
// TODO: we could do this in a more sophisticated way inside
// AAReturnedValues, e.g., track all values that escape through returns
// directly somehow.
auto CheckReturnedArgs = [&](const AAReturnedValues &RVAA) {
bool SeenConstant = false;
for (auto &It : RVAA.returned_values()) {
if (isa<Constant>(It.first)) {
if (SeenConstant)
return false;
SeenConstant = true;
} else if (!isa<Argument>(It.first) ||
It.first == getAssociatedArgument())
return false;
}
return true;
};
const auto &NoUnwindAA = A.getAAFor<AANoUnwind>(*this, FnPos);
if (NoUnwindAA.isAssumedNoUnwind()) {
bool IsVoidTy = F->getReturnType()->isVoidTy();
const AAReturnedValues *RVAA =
IsVoidTy ? nullptr : &A.getAAFor<AAReturnedValues>(*this, FnPos);
if (IsVoidTy || CheckReturnedArgs(*RVAA)) {
T.addKnownBits(NOT_CAPTURED_IN_RET);
if (T.isKnown(NOT_CAPTURED_IN_MEM))
return ChangeStatus::UNCHANGED;
if (NoUnwindAA.isKnownNoUnwind() &&
(IsVoidTy || RVAA->getState().isAtFixpoint())) {
addKnownBits(NOT_CAPTURED_IN_RET);
if (isKnown(NOT_CAPTURED_IN_MEM))
return indicateOptimisticFixpoint();
}
}
}
// Use the CaptureTracker interface and logic with the specialized tracker,
// defined in AACaptureUseTracker, that can look at in-flight abstract
// attributes and directly updates the assumed state.
SmallVector<const Value *, 4> PotentialCopies;
unsigned RemainingUsesToExplore = DefaultMaxUsesToExplore;
AACaptureUseTracker Tracker(A, *this, IsDeadAA, T, PotentialCopies,
RemainingUsesToExplore);
// Check all potential copies of the associated value until we can assume
// none will be captured or we have to assume at least one might be.
unsigned Idx = 0;
PotentialCopies.push_back(V);
while (T.isAssumed(NO_CAPTURE_MAYBE_RETURNED) && Idx < PotentialCopies.size())
Tracker.valueMayBeCaptured(PotentialCopies[Idx++]);
AANoCapture::StateType &S = getState();
auto Assumed = S.getAssumed();
S.intersectAssumedBits(T.getAssumed());
if (!isAssumedNoCaptureMaybeReturned())
return indicatePessimisticFixpoint();
return Assumed == S.getAssumed() ? ChangeStatus::UNCHANGED
: ChangeStatus::CHANGED;
}
/// NoCapture attribute for function arguments.
struct AANoCaptureArgument final : AANoCaptureImpl {
AANoCaptureArgument(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(nocapture) }
};
/// NoCapture attribute for call site arguments.
struct AANoCaptureCallSiteArgument final : AANoCaptureImpl {
AANoCaptureCallSiteArgument(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (Argument *Arg = getAssociatedArgument())
if (Arg->hasByValAttr())
indicateOptimisticFixpoint();
AANoCaptureImpl::initialize(A);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
if (!Arg)
return indicatePessimisticFixpoint();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AANoCapture>(*this, ArgPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AANoCapture::StateType &>(ArgAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override{STATS_DECLTRACK_CSARG_ATTR(nocapture)};
};
/// NoCapture attribute for floating values.
struct AANoCaptureFloating final : AANoCaptureImpl {
AANoCaptureFloating(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(nocapture)
}
};
/// NoCapture attribute for function return value.
struct AANoCaptureReturned final : AANoCaptureImpl {
AANoCaptureReturned(const IRPosition &IRP) : AANoCaptureImpl(IRP) {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("NoCapture is not applicable to function returns!");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// NoCapture attribute deduction for a call site return value.
struct AANoCaptureCallSiteReturned final : AANoCaptureImpl {
AANoCaptureCallSiteReturned(const IRPosition &IRP) : AANoCaptureImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(nocapture)
}
};
/// ------------------ Value Simplify Attribute ----------------------------
struct AAValueSimplifyImpl : AAValueSimplify {
AAValueSimplifyImpl(const IRPosition &IRP) : AAValueSimplify(IRP) {}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
return getAssumed() ? (getKnown() ? "simplified" : "maybe-simple")
: "not-simple";
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
/// See AAValueSimplify::getAssumedSimplifiedValue()
Optional<Value *> getAssumedSimplifiedValue(Attributor &A) const override {
if (!getAssumed())
return const_cast<Value *>(&getAssociatedValue());
return SimplifiedAssociatedValue;
}
void initialize(Attributor &A) override {}
/// Helper function for querying AAValueSimplify and updating candicate.
/// \param QueryingValue Value trying to unify with SimplifiedValue
/// \param AccumulatedSimplifiedValue Current simplification result.
static bool checkAndUpdate(Attributor &A, const AbstractAttribute &QueryingAA,
Value &QueryingValue,
Optional<Value *> &AccumulatedSimplifiedValue) {
// FIXME: Add a typecast support.
auto &ValueSimpifyAA = A.getAAFor<AAValueSimplify>(
QueryingAA, IRPosition::value(QueryingValue));
Optional<Value *> QueryingValueSimplified =
ValueSimpifyAA.getAssumedSimplifiedValue(A);
if (!QueryingValueSimplified.hasValue())
return true;
if (!QueryingValueSimplified.getValue())
return false;
Value &QueryingValueSimplifiedUnwrapped =
*QueryingValueSimplified.getValue();
if (isa<UndefValue>(QueryingValueSimplifiedUnwrapped))
return true;
if (AccumulatedSimplifiedValue.hasValue())
return AccumulatedSimplifiedValue == QueryingValueSimplified;
LLVM_DEBUG(dbgs() << "[Attributor][ValueSimplify] " << QueryingValue
<< " is assumed to be "
<< QueryingValueSimplifiedUnwrapped << "\n");
AccumulatedSimplifiedValue = QueryingValueSimplified;
return true;
}
bool askSimplifiedValueForAAValueConstantRange(Attributor &A) {
if (!getAssociatedValue().getType()->isIntegerTy())
return false;
const auto &ValueConstantRangeAA =
A.getAAFor<AAValueConstantRange>(*this, getIRPosition());
Optional<ConstantInt *> COpt =
ValueConstantRangeAA.getAssumedConstantInt(A);
if (COpt.hasValue()) {
if (auto *C = COpt.getValue())
SimplifiedAssociatedValue = C;
else
return false;
} else {
// FIXME: It should be llvm::None but if you set llvm::None,
// values are mistakenly infered as `undef` now.
SimplifiedAssociatedValue = &getAssociatedValue();
}
return true;
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
if (!SimplifiedAssociatedValue.hasValue() ||
!SimplifiedAssociatedValue.getValue())
return Changed;
if (auto *C = dyn_cast<Constant>(SimplifiedAssociatedValue.getValue())) {
// We can replace the AssociatedValue with the constant.
Value &V = getAssociatedValue();
if (!V.user_empty() && &V != C && V.getType() == C->getType()) {
LLVM_DEBUG(dbgs() << "[Attributor][ValueSimplify] " << V << " -> " << *C
<< "\n");
A.changeValueAfterManifest(V, *C);
Changed = ChangeStatus::CHANGED;
}
}
return Changed | AAValueSimplify::manifest(A);
}
/// See AbstractState::indicatePessimisticFixpoint(...).
ChangeStatus indicatePessimisticFixpoint() override {
// NOTE: Associated value will be returned in a pessimistic fixpoint and is
// regarded as known. That's why`indicateOptimisticFixpoint` is called.
SimplifiedAssociatedValue = &getAssociatedValue();
indicateOptimisticFixpoint();
return ChangeStatus::CHANGED;
}
protected:
// An assumed simplified value. Initially, it is set to Optional::None, which
// means that the value is not clear under current assumption. If in the
// pessimistic state, getAssumedSimplifiedValue doesn't return this value but
// returns orignal associated value.
Optional<Value *> SimplifiedAssociatedValue;
};
struct AAValueSimplifyArgument final : AAValueSimplifyImpl {
AAValueSimplifyArgument(const IRPosition &IRP) : AAValueSimplifyImpl(IRP) {}
void initialize(Attributor &A) override {
AAValueSimplifyImpl::initialize(A);
if (!getAssociatedFunction() || getAssociatedFunction()->isDeclaration())
indicatePessimisticFixpoint();
if (hasAttr({Attribute::InAlloca, Attribute::StructRet, Attribute::Nest},
/* IgnoreSubsumingPositions */ true))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// Byval is only replacable if it is readonly otherwise we would write into
// the replaced value and not the copy that byval creates implicitly.
Argument *Arg = getAssociatedArgument();
if (Arg->hasByValAttr()) {
const auto &MemAA = A.getAAFor<AAMemoryBehavior>(*this, getIRPosition());
if (!MemAA.isAssumedReadOnly())
return indicatePessimisticFixpoint();
}
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
auto PredForCallSite = [&](AbstractCallSite ACS) {
// Check if we have an associated argument or not (which can happen for
// callback calls).
Value *ArgOp = ACS.getCallArgOperand(getArgNo());
if (!ArgOp)
return false;
// We can only propagate thread independent values through callbacks.
// This is different to direct/indirect call sites because for them we
// know the thread executing the caller and callee is the same. For
// callbacks this is not guaranteed, thus a thread dependent value could
// be different for the caller and callee, making it invalid to propagate.
if (ACS.isCallbackCall())
if (auto *C = dyn_cast<Constant>(ArgOp))
if (C->isThreadDependent())
return false;
return checkAndUpdate(A, *this, *ArgOp, SimplifiedAssociatedValue);
};
if (!A.checkForAllCallSites(PredForCallSite, *this, true))
if (!askSimplifiedValueForAAValueConstantRange(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(value_simplify)
}
};
struct AAValueSimplifyReturned : AAValueSimplifyImpl {
AAValueSimplifyReturned(const IRPosition &IRP) : AAValueSimplifyImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
auto PredForReturned = [&](Value &V) {
return checkAndUpdate(A, *this, V, SimplifiedAssociatedValue);
};
if (!A.checkForAllReturnedValues(PredForReturned, *this))
if (!askSimplifiedValueForAAValueConstantRange(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(value_simplify)
}
};
struct AAValueSimplifyFloating : AAValueSimplifyImpl {
AAValueSimplifyFloating(const IRPosition &IRP) : AAValueSimplifyImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
Value &V = getAnchorValue();
// TODO: add other stuffs
if (isa<Constant>(V))
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
bool HasValueBefore = SimplifiedAssociatedValue.hasValue();
auto VisitValueCB = [&](Value &V, BooleanState, bool Stripped) -> bool {
auto &AA = A.getAAFor<AAValueSimplify>(*this, IRPosition::value(V));
if (!Stripped && this == &AA) {
// TODO: Look the instruction and check recursively.
LLVM_DEBUG(
dbgs() << "[Attributor][ValueSimplify] Can't be stripped more : "
<< V << "\n");
return false;
}
return checkAndUpdate(A, *this, V, SimplifiedAssociatedValue);
};
if (!genericValueTraversal<AAValueSimplify, BooleanState>(
A, getIRPosition(), *this, static_cast<BooleanState &>(*this),
VisitValueCB))
if (!askSimplifiedValueForAAValueConstantRange(A))
return indicatePessimisticFixpoint();
// If a candicate was found in this update, return CHANGED.
return HasValueBefore == SimplifiedAssociatedValue.hasValue()
? ChangeStatus::UNCHANGED
: ChangeStatus ::CHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(value_simplify)
}
};
struct AAValueSimplifyFunction : AAValueSimplifyImpl {
AAValueSimplifyFunction(const IRPosition &IRP) : AAValueSimplifyImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
SimplifiedAssociatedValue = &getAnchorValue();
indicateOptimisticFixpoint();
}
/// See AbstractAttribute::initialize(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable(
"AAValueSimplify(Function|CallSite)::updateImpl will not be called");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FN_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSite : AAValueSimplifyFunction {
AAValueSimplifyCallSite(const IRPosition &IRP)
: AAValueSimplifyFunction(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CS_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSiteReturned : AAValueSimplifyReturned {
AAValueSimplifyCallSiteReturned(const IRPosition &IRP)
: AAValueSimplifyReturned(IRP) {}
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(value_simplify)
}
};
struct AAValueSimplifyCallSiteArgument : AAValueSimplifyFloating {
AAValueSimplifyCallSiteArgument(const IRPosition &IRP)
: AAValueSimplifyFloating(IRP) {}
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(value_simplify)
}
};
/// ----------------------- Heap-To-Stack Conversion ---------------------------
struct AAHeapToStackImpl : public AAHeapToStack {
AAHeapToStackImpl(const IRPosition &IRP) : AAHeapToStack(IRP) {}
const std::string getAsStr() const override {
return "[H2S] Mallocs: " + std::to_string(MallocCalls.size());
}
ChangeStatus manifest(Attributor &A) override {
assert(getState().isValidState() &&
"Attempted to manifest an invalid state!");
ChangeStatus HasChanged = ChangeStatus::UNCHANGED;
Function *F = getAssociatedFunction();
const auto *TLI = A.getInfoCache().getTargetLibraryInfoForFunction(*F);
for (Instruction *MallocCall : MallocCalls) {
// This malloc cannot be replaced.
if (BadMallocCalls.count(MallocCall))
continue;
for (Instruction *FreeCall : FreesForMalloc[MallocCall]) {
LLVM_DEBUG(dbgs() << "H2S: Removing free call: " << *FreeCall << "\n");
A.deleteAfterManifest(*FreeCall);
HasChanged = ChangeStatus::CHANGED;
}
LLVM_DEBUG(dbgs() << "H2S: Removing malloc call: " << *MallocCall
<< "\n");
Constant *Size;
if (isCallocLikeFn(MallocCall, TLI)) {
auto *Num = cast<ConstantInt>(MallocCall->getOperand(0));
auto *SizeT = dyn_cast<ConstantInt>(MallocCall->getOperand(1));
APInt TotalSize = SizeT->getValue() * Num->getValue();
Size =
ConstantInt::get(MallocCall->getOperand(0)->getType(), TotalSize);
} else {
Size = cast<ConstantInt>(MallocCall->getOperand(0));
}
unsigned AS = cast<PointerType>(MallocCall->getType())->getAddressSpace();
Instruction *AI = new AllocaInst(Type::getInt8Ty(F->getContext()), AS,
Size, "", MallocCall->getNextNode());
if (AI->getType() != MallocCall->getType())
AI = new BitCastInst(AI, MallocCall->getType(), "malloc_bc",
AI->getNextNode());
replaceAllInstructionUsesWith(*MallocCall, *AI);
if (auto *II = dyn_cast<InvokeInst>(MallocCall)) {
auto *NBB = II->getNormalDest();
BranchInst::Create(NBB, MallocCall->getParent());
A.deleteAfterManifest(*MallocCall);
} else {
A.deleteAfterManifest(*MallocCall);
}
if (isCallocLikeFn(MallocCall, TLI)) {
auto *BI = new BitCastInst(AI, MallocCall->getType(), "calloc_bc",
AI->getNextNode());
Value *Ops[] = {
BI, ConstantInt::get(F->getContext(), APInt(8, 0, false)), Size,
ConstantInt::get(Type::getInt1Ty(F->getContext()), false)};
Type *Tys[] = {BI->getType(), MallocCall->getOperand(0)->getType()};
Module *M = F->getParent();
Function *Fn = Intrinsic::getDeclaration(M, Intrinsic::memset, Tys);
CallInst::Create(Fn, Ops, "", BI->getNextNode());
}
HasChanged = ChangeStatus::CHANGED;
}
return HasChanged;
}
/// Collection of all malloc calls in a function.
SmallSetVector<Instruction *, 4> MallocCalls;
/// Collection of malloc calls that cannot be converted.
DenseSet<const Instruction *> BadMallocCalls;
/// A map for each malloc call to the set of associated free calls.
DenseMap<Instruction *, SmallPtrSet<Instruction *, 4>> FreesForMalloc;
ChangeStatus updateImpl(Attributor &A) override;
};
ChangeStatus AAHeapToStackImpl::updateImpl(Attributor &A) {
const Function *F = getAssociatedFunction();
const auto *TLI = A.getInfoCache().getTargetLibraryInfoForFunction(*F);
MustBeExecutedContextExplorer &Explorer =
A.getInfoCache().getMustBeExecutedContextExplorer();
auto FreeCheck = [&](Instruction &I) {
const auto &Frees = FreesForMalloc.lookup(&I);
if (Frees.size() != 1)
return false;
Instruction *UniqueFree = *Frees.begin();
return Explorer.findInContextOf(UniqueFree, I.getNextNode());
};
auto UsesCheck = [&](Instruction &I) {
bool ValidUsesOnly = true;
bool MustUse = true;
auto Pred = [&](const Use &U, bool &Follow) -> bool {
Instruction *UserI = cast<Instruction>(U.getUser());
if (isa<LoadInst>(UserI))
return true;
if (auto *SI = dyn_cast<StoreInst>(UserI)) {
if (SI->getValueOperand() == U.get()) {
LLVM_DEBUG(dbgs()
<< "[H2S] escaping store to memory: " << *UserI << "\n");
ValidUsesOnly = false;
} else {
// A store into the malloc'ed memory is fine.
}
return true;
}
if (auto *CB = dyn_cast<CallBase>(UserI)) {
if (!CB->isArgOperand(&U) || CB->isLifetimeStartOrEnd())
return true;
// Record malloc.
if (isFreeCall(UserI, TLI)) {
if (MustUse) {
FreesForMalloc[&I].insert(UserI);
} else {
LLVM_DEBUG(dbgs() << "[H2S] free potentially on different mallocs: "
<< *UserI << "\n");
ValidUsesOnly = false;
}
return true;
}
unsigned ArgNo = CB->getArgOperandNo(&U);
const auto &NoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
// If a callsite argument use is nofree, we are fine.
const auto &ArgNoFreeAA = A.getAAFor<AANoFree>(
*this, IRPosition::callsite_argument(*CB, ArgNo));
if (!NoCaptureAA.isAssumedNoCapture() ||
!ArgNoFreeAA.isAssumedNoFree()) {
LLVM_DEBUG(dbgs() << "[H2S] Bad user: " << *UserI << "\n");
ValidUsesOnly = false;
}
return true;
}
if (isa<GetElementPtrInst>(UserI) || isa<BitCastInst>(UserI) ||
isa<PHINode>(UserI) || isa<SelectInst>(UserI)) {
MustUse &= !(isa<PHINode>(UserI) || isa<SelectInst>(UserI));
Follow = true;
return true;
}
// Unknown user for which we can not track uses further (in a way that
// makes sense).
LLVM_DEBUG(dbgs() << "[H2S] Unknown user: " << *UserI << "\n");
ValidUsesOnly = false;
return true;
};
A.checkForAllUses(Pred, *this, I);
return ValidUsesOnly;
};
auto MallocCallocCheck = [&](Instruction &I) {
if (BadMallocCalls.count(&I))
return true;
bool IsMalloc = isMallocLikeFn(&I, TLI);
bool IsCalloc = !IsMalloc && isCallocLikeFn(&I, TLI);
if (!IsMalloc && !IsCalloc) {
BadMallocCalls.insert(&I);
return true;
}
if (IsMalloc) {
if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(0)))
if (Size->getValue().ule(MaxHeapToStackSize))
if (UsesCheck(I) || FreeCheck(I)) {
MallocCalls.insert(&I);
return true;
}
} else if (IsCalloc) {
bool Overflow = false;
if (auto *Num = dyn_cast<ConstantInt>(I.getOperand(0)))
if (auto *Size = dyn_cast<ConstantInt>(I.getOperand(1)))
if ((Size->getValue().umul_ov(Num->getValue(), Overflow))
.ule(MaxHeapToStackSize))
if (!Overflow && (UsesCheck(I) || FreeCheck(I))) {
MallocCalls.insert(&I);
return true;
}
}
BadMallocCalls.insert(&I);
return true;
};
size_t NumBadMallocs = BadMallocCalls.size();
A.checkForAllCallLikeInstructions(MallocCallocCheck, *this);
if (NumBadMallocs != BadMallocCalls.size())
return ChangeStatus::CHANGED;
return ChangeStatus::UNCHANGED;
}
struct AAHeapToStackFunction final : public AAHeapToStackImpl {
AAHeapToStackFunction(const IRPosition &IRP) : AAHeapToStackImpl(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECL(MallocCalls, Function,
"Number of malloc calls converted to allocas");
for (auto *C : MallocCalls)
if (!BadMallocCalls.count(C))
++BUILD_STAT_NAME(MallocCalls, Function);
}
};
/// -------------------- Memory Behavior Attributes ----------------------------
/// Includes read-none, read-only, and write-only.
/// ----------------------------------------------------------------------------
struct AAMemoryBehaviorImpl : public AAMemoryBehavior {
AAMemoryBehaviorImpl(const IRPosition &IRP) : AAMemoryBehavior(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
getKnownStateFromValue(getIRPosition(), getState());
IRAttribute::initialize(A);
}
/// Return the memory behavior information encoded in the IR for \p IRP.
static void getKnownStateFromValue(const IRPosition &IRP,
BitIntegerState &State,
bool IgnoreSubsumingPositions = false) {
SmallVector<Attribute, 2> Attrs;
IRP.getAttrs(AttrKinds, Attrs, IgnoreSubsumingPositions);
for (const Attribute &Attr : Attrs) {
switch (Attr.getKindAsEnum()) {
case Attribute::ReadNone:
State.addKnownBits(NO_ACCESSES);
break;
case Attribute::ReadOnly:
State.addKnownBits(NO_WRITES);
break;
case Attribute::WriteOnly:
State.addKnownBits(NO_READS);
break;
default:
llvm_unreachable("Unexpcted attribute!");
}
}
if (auto *I = dyn_cast<Instruction>(&IRP.getAnchorValue())) {
if (!I->mayReadFromMemory())
State.addKnownBits(NO_READS);
if (!I->mayWriteToMemory())
State.addKnownBits(NO_WRITES);
}
}
/// See AbstractAttribute::getDeducedAttributes(...).
void getDeducedAttributes(LLVMContext &Ctx,
SmallVectorImpl<Attribute> &Attrs) const override {
assert(Attrs.size() == 0);
if (isAssumedReadNone())
Attrs.push_back(Attribute::get(Ctx, Attribute::ReadNone));
else if (isAssumedReadOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::ReadOnly));
else if (isAssumedWriteOnly())
Attrs.push_back(Attribute::get(Ctx, Attribute::WriteOnly));
assert(Attrs.size() <= 1);
}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
const IRPosition &IRP = getIRPosition();
// Check if we would improve the existing attributes first.
SmallVector<Attribute, 4> DeducedAttrs;
getDeducedAttributes(IRP.getAnchorValue().getContext(), DeducedAttrs);
if (llvm::all_of(DeducedAttrs, [&](const Attribute &Attr) {
return IRP.hasAttr(Attr.getKindAsEnum(),
/* IgnoreSubsumingPositions */ true);
}))
return ChangeStatus::UNCHANGED;
// Clear existing attributes.
IRP.removeAttrs(AttrKinds);
// Use the generic manifest method.
return IRAttribute::manifest(A);
}
/// See AbstractState::getAsStr().
const std::string getAsStr() const override {
if (isAssumedReadNone())
return "readnone";
if (isAssumedReadOnly())
return "readonly";
if (isAssumedWriteOnly())
return "writeonly";
return "may-read/write";
}
/// The set of IR attributes AAMemoryBehavior deals with.
static const Attribute::AttrKind AttrKinds[3];
};
const Attribute::AttrKind AAMemoryBehaviorImpl::AttrKinds[] = {
Attribute::ReadNone, Attribute::ReadOnly, Attribute::WriteOnly};
/// Memory behavior attribute for a floating value.
struct AAMemoryBehaviorFloating : AAMemoryBehaviorImpl {
AAMemoryBehaviorFloating(const IRPosition &IRP) : AAMemoryBehaviorImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryBehaviorImpl::initialize(A);
// Initialize the use vector with all direct uses of the associated value.
for (const Use &U : getAssociatedValue().uses())
Uses.insert(&U);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override;
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_FLOATING_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_FLOATING_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_FLOATING_ATTR(writeonly)
}
private:
/// Return true if users of \p UserI might access the underlying
/// variable/location described by \p U and should therefore be analyzed.
bool followUsersOfUseIn(Attributor &A, const Use *U,
const Instruction *UserI);
/// Update the state according to the effect of use \p U in \p UserI.
void analyzeUseIn(Attributor &A, const Use *U, const Instruction *UserI);
protected:
/// Container for (transitive) uses of the associated argument.
SetVector<const Use *> Uses;
};
/// Memory behavior attribute for function argument.
struct AAMemoryBehaviorArgument : AAMemoryBehaviorFloating {
AAMemoryBehaviorArgument(const IRPosition &IRP)
: AAMemoryBehaviorFloating(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
intersectAssumedBits(BEST_STATE);
const IRPosition &IRP = getIRPosition();
// TODO: Make IgnoreSubsumingPositions a property of an IRAttribute so we
// can query it when we use has/getAttr. That would allow us to reuse the
// initialize of the base class here.
bool HasByVal =
IRP.hasAttr({Attribute::ByVal}, /* IgnoreSubsumingPositions */ true);
getKnownStateFromValue(IRP, getState(),
/* IgnoreSubsumingPositions */ HasByVal);
// Initialize the use vector with all direct uses of the associated value.
Argument *Arg = getAssociatedArgument();
if (!Arg || !Arg->getParent()->hasExactDefinition()) {
indicatePessimisticFixpoint();
} else {
// Initialize the use vector with all direct uses of the associated value.
for (const Use &U : Arg->uses())
Uses.insert(&U);
}
}
ChangeStatus manifest(Attributor &A) override {
// TODO: From readattrs.ll: "inalloca parameters are always
// considered written"
if (hasAttr({Attribute::InAlloca})) {
removeKnownBits(NO_WRITES);
removeAssumedBits(NO_WRITES);
}
return AAMemoryBehaviorFloating::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_ARG_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_ARG_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_ARG_ATTR(writeonly)
}
};
struct AAMemoryBehaviorCallSiteArgument final : AAMemoryBehaviorArgument {
AAMemoryBehaviorCallSiteArgument(const IRPosition &IRP)
: AAMemoryBehaviorArgument(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
if (Argument *Arg = getAssociatedArgument()) {
if (Arg->hasByValAttr()) {
addKnownBits(NO_WRITES);
removeKnownBits(NO_READS);
removeAssumedBits(NO_READS);
}
} else {
}
AAMemoryBehaviorArgument::initialize(A);
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Argument *Arg = getAssociatedArgument();
const IRPosition &ArgPos = IRPosition::argument(*Arg);
auto &ArgAA = A.getAAFor<AAMemoryBehavior>(*this, ArgPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AAMemoryBehavior::StateType &>(ArgAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_CSARG_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_CSARG_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_CSARG_ATTR(writeonly)
}
};
/// Memory behavior attribute for a call site return position.
struct AAMemoryBehaviorCallSiteReturned final : AAMemoryBehaviorFloating {
AAMemoryBehaviorCallSiteReturned(const IRPosition &IRP)
: AAMemoryBehaviorFloating(IRP) {}
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
// We do not annotate returned values.
return ChangeStatus::UNCHANGED;
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {}
};
/// An AA to represent the memory behavior function attributes.
struct AAMemoryBehaviorFunction final : public AAMemoryBehaviorImpl {
AAMemoryBehaviorFunction(const IRPosition &IRP) : AAMemoryBehaviorImpl(IRP) {}
/// See AbstractAttribute::updateImpl(Attributor &A).
virtual ChangeStatus updateImpl(Attributor &A) override;
/// See AbstractAttribute::manifest(...).
ChangeStatus manifest(Attributor &A) override {
Function &F = cast<Function>(getAnchorValue());
if (isAssumedReadNone()) {
F.removeFnAttr(Attribute::ArgMemOnly);
F.removeFnAttr(Attribute::InaccessibleMemOnly);
F.removeFnAttr(Attribute::InaccessibleMemOrArgMemOnly);
}
return AAMemoryBehaviorImpl::manifest(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_FN_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_FN_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_FN_ATTR(writeonly)
}
};
/// AAMemoryBehavior attribute for call sites.
struct AAMemoryBehaviorCallSite final : AAMemoryBehaviorImpl {
AAMemoryBehaviorCallSite(const IRPosition &IRP) : AAMemoryBehaviorImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAMemoryBehaviorImpl::initialize(A);
Function *F = getAssociatedFunction();
if (!F || !F->hasExactDefinition())
indicatePessimisticFixpoint();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Once we have call site specific value information we can provide
// call site specific liveness liveness information and then it makes
// sense to specialize attributes for call sites arguments instead of
// redirecting requests to the callee argument.
Function *F = getAssociatedFunction();
const IRPosition &FnPos = IRPosition::function(*F);
auto &FnAA = A.getAAFor<AAMemoryBehavior>(*this, FnPos);
return clampStateAndIndicateChange(
getState(),
static_cast<const AAMemoryBehavior::StateType &>(FnAA.getState()));
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
if (isAssumedReadNone())
STATS_DECLTRACK_CS_ATTR(readnone)
else if (isAssumedReadOnly())
STATS_DECLTRACK_CS_ATTR(readonly)
else if (isAssumedWriteOnly())
STATS_DECLTRACK_CS_ATTR(writeonly)
}
};
} // namespace
ChangeStatus AAMemoryBehaviorFunction::updateImpl(Attributor &A) {
// The current assumed state used to determine a change.
auto AssumedState = getAssumed();
auto CheckRWInst = [&](Instruction &I) {
// If the instruction has an own memory behavior state, use it to restrict
// the local state. No further analysis is required as the other memory
// state is as optimistic as it gets.
if (ImmutableCallSite ICS = ImmutableCallSite(&I)) {
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(
*this, IRPosition::callsite_function(ICS));
intersectAssumedBits(MemBehaviorAA.getAssumed());
return !isAtFixpoint();
}
// Remove access kind modifiers if necessary.
if (I.mayReadFromMemory())
removeAssumedBits(NO_READS);
if (I.mayWriteToMemory())
removeAssumedBits(NO_WRITES);
return !isAtFixpoint();
};
if (!A.checkForAllReadWriteInstructions(CheckRWInst, *this))
return indicatePessimisticFixpoint();
return (AssumedState != getAssumed()) ? ChangeStatus::CHANGED
: ChangeStatus::UNCHANGED;
}
ChangeStatus AAMemoryBehaviorFloating::updateImpl(Attributor &A) {
const IRPosition &IRP = getIRPosition();
const IRPosition &FnPos = IRPosition::function_scope(IRP);
AAMemoryBehavior::StateType &S = getState();
// First, check the function scope. We take the known information and we avoid
// work if the assumed information implies the current assumed information for
// this attribute. This is a valid for all but byval arguments.
Argument *Arg = IRP.getAssociatedArgument();
AAMemoryBehavior::base_t FnMemAssumedState =
AAMemoryBehavior::StateType::getWorstState();
if (!Arg || !Arg->hasByValAttr()) {
const auto &FnMemAA = A.getAAFor<AAMemoryBehavior>(*this, FnPos);
FnMemAssumedState = FnMemAA.getAssumed();
S.addKnownBits(FnMemAA.getKnown());
if ((S.getAssumed() & FnMemAA.getAssumed()) == S.getAssumed())
return ChangeStatus::UNCHANGED;
}
// Make sure the value is not captured (except through "return"), if
// it is, any information derived would be irrelevant anyway as we cannot
// check the potential aliases introduced by the capture. However, no need
// to fall back to anythign less optimistic than the function state.
const auto &ArgNoCaptureAA = A.getAAFor<AANoCapture>(
*this, IRP, /* TrackDependence */ true, DepClassTy::OPTIONAL);
if (!ArgNoCaptureAA.isAssumedNoCaptureMaybeReturned()) {
S.intersectAssumedBits(FnMemAssumedState);
return ChangeStatus::CHANGED;
}
// The current assumed state used to determine a change.
auto AssumedState = S.getAssumed();
// Liveness information to exclude dead users.
// TODO: Take the FnPos once we have call site specific liveness information.
const auto &LivenessAA = A.getAAFor<AAIsDead>(
*this, IRPosition::function(*IRP.getAssociatedFunction()));
// Visit and expand uses until all are analyzed or a fixpoint is reached.
for (unsigned i = 0; i < Uses.size() && !isAtFixpoint(); i++) {
const Use *U = Uses[i];
Instruction *UserI = cast<Instruction>(U->getUser());
LLVM_DEBUG(dbgs() << "[AAMemoryBehavior] Use: " << **U << " in " << *UserI
<< " [Dead: " << (LivenessAA.isAssumedDead(UserI))
<< "]\n");
if (LivenessAA.isAssumedDead(UserI))
continue;
// Check if the users of UserI should also be visited.
if (followUsersOfUseIn(A, U, UserI))
for (const Use &UserIUse : UserI->uses())
Uses.insert(&UserIUse);
// If UserI might touch memory we analyze the use in detail.
if (UserI->mayReadOrWriteMemory())
analyzeUseIn(A, U, UserI);
}
return (AssumedState != getAssumed()) ? ChangeStatus::CHANGED
: ChangeStatus::UNCHANGED;
}
bool AAMemoryBehaviorFloating::followUsersOfUseIn(Attributor &A, const Use *U,
const Instruction *UserI) {
// The loaded value is unrelated to the pointer argument, no need to
// follow the users of the load.
if (isa<LoadInst>(UserI))
return false;
// By default we follow all uses assuming UserI might leak information on U,
// we have special handling for call sites operands though.
ImmutableCallSite ICS(UserI);
if (!ICS || !ICS.isArgOperand(U))
return true;
// If the use is a call argument known not to be captured, the users of
// the call do not need to be visited because they have to be unrelated to
// the input. Note that this check is not trivial even though we disallow
// general capturing of the underlying argument. The reason is that the
// call might the argument "through return", which we allow and for which we
// need to check call users.
unsigned ArgNo = ICS.getArgumentNo(U);
const auto &ArgNoCaptureAA =
A.getAAFor<AANoCapture>(*this, IRPosition::callsite_argument(ICS, ArgNo));
return !ArgNoCaptureAA.isAssumedNoCapture();
}
void AAMemoryBehaviorFloating::analyzeUseIn(Attributor &A, const Use *U,
const Instruction *UserI) {
assert(UserI->mayReadOrWriteMemory());
switch (UserI->getOpcode()) {
default:
// TODO: Handle all atomics and other side-effect operations we know of.
break;
case Instruction::Load:
// Loads cause the NO_READS property to disappear.
removeAssumedBits(NO_READS);
return;
case Instruction::Store:
// Stores cause the NO_WRITES property to disappear if the use is the
// pointer operand. Note that we do assume that capturing was taken care of
// somewhere else.
if (cast<StoreInst>(UserI)->getPointerOperand() == U->get())
removeAssumedBits(NO_WRITES);
return;
case Instruction::Call:
case Instruction::CallBr:
case Instruction::Invoke: {
// For call sites we look at the argument memory behavior attribute (this
// could be recursive!) in order to restrict our own state.
ImmutableCallSite ICS(UserI);
// Give up on operand bundles.
if (ICS.isBundleOperand(U)) {
indicatePessimisticFixpoint();
return;
}
// Calling a function does read the function pointer, maybe write it if the
// function is self-modifying.
if (ICS.isCallee(U)) {
removeAssumedBits(NO_READS);
break;
}
// Adjust the possible access behavior based on the information on the
// argument.
unsigned ArgNo = ICS.getArgumentNo(U);
const IRPosition &ArgPos = IRPosition::callsite_argument(ICS, ArgNo);
const auto &MemBehaviorAA = A.getAAFor<AAMemoryBehavior>(*this, ArgPos);
// "assumed" has at most the same bits as the MemBehaviorAA assumed
// and at least "known".
intersectAssumedBits(MemBehaviorAA.getAssumed());
return;
}
};
// Generally, look at the "may-properties" and adjust the assumed state if we
// did not trigger special handling before.
if (UserI->mayReadFromMemory())
removeAssumedBits(NO_READS);
if (UserI->mayWriteToMemory())
removeAssumedBits(NO_WRITES);
}
/// ------------------ Value Constant Range Attribute -------------------------
struct AAValueConstantRangeImpl : AAValueConstantRange {
using StateType = IntegerRangeState;
AAValueConstantRangeImpl(const IRPosition &IRP) : AAValueConstantRange(IRP) {}
/// See AbstractAttribute::getAsStr().
const std::string getAsStr() const override {
std::string Str;
llvm::raw_string_ostream OS(Str);
OS << "range(" << getBitWidth() << ")<";
getKnown().print(OS);
OS << " / ";
getAssumed().print(OS);
OS << ">";
return OS.str();
}
/// Helper function to get a SCEV expr for the associated value at program
/// point \p I.
const SCEV *getSCEV(Attributor &A, const Instruction *I = nullptr) const {
if (!getAnchorScope())
return nullptr;
ScalarEvolution *SE =
A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(
*getAnchorScope());
LoopInfo *LI = A.getInfoCache().getAnalysisResultForFunction<LoopAnalysis>(
*getAnchorScope());
if (!SE || !LI)
return nullptr;
const SCEV *S = SE->getSCEV(&getAssociatedValue());
if (!I)
return S;
return SE->getSCEVAtScope(S, LI->getLoopFor(I->getParent()));
}
/// Helper function to get a range from SCEV for the associated value at
/// program point \p I.
ConstantRange getConstantRangeFromSCEV(Attributor &A,
const Instruction *I = nullptr) const {
if (!getAnchorScope())
return getWorstState(getBitWidth());
ScalarEvolution *SE =
A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(
*getAnchorScope());
const SCEV *S = getSCEV(A, I);
if (!SE || !S)
return getWorstState(getBitWidth());
return SE->getUnsignedRange(S);
}
/// Helper function to get a range from LVI for the associated value at
/// program point \p I.
ConstantRange
getConstantRangeFromLVI(Attributor &A,
const Instruction *CtxI = nullptr) const {
if (!getAnchorScope())
return getWorstState(getBitWidth());
LazyValueInfo *LVI =
A.getInfoCache().getAnalysisResultForFunction<LazyValueAnalysis>(
*getAnchorScope());
if (!LVI || !CtxI)
return getWorstState(getBitWidth());
return LVI->getConstantRange(&getAssociatedValue(),
const_cast<BasicBlock *>(CtxI->getParent()),
const_cast<Instruction *>(CtxI));
}
/// See AAValueConstantRange::getKnownConstantRange(..).
ConstantRange
getKnownConstantRange(Attributor &A,
const Instruction *CtxI = nullptr) const override {
if (!CtxI || CtxI == getCtxI())
return getKnown();
ConstantRange LVIR = getConstantRangeFromLVI(A, CtxI);
ConstantRange SCEVR = getConstantRangeFromSCEV(A, CtxI);
return getKnown().intersectWith(SCEVR).intersectWith(LVIR);
}
/// See AAValueConstantRange::getAssumedConstantRange(..).
ConstantRange
getAssumedConstantRange(Attributor &A,
const Instruction *CtxI = nullptr) const override {
// TODO: Make SCEV use Attributor assumption.
// We may be able to bound a variable range via assumptions in
// Attributor. ex.) If x is assumed to be in [1, 3] and y is known to
// evolve to x^2 + x, then we can say that y is in [2, 12].
if (!CtxI || CtxI == getCtxI())
return getAssumed();
ConstantRange LVIR = getConstantRangeFromLVI(A, CtxI);
ConstantRange SCEVR = getConstantRangeFromSCEV(A, CtxI);
return getAssumed().intersectWith(SCEVR).intersectWith(LVIR);
}
/// See AbstractAttribute::initialize(..).
void initialize(Attributor &A) override {
// Intersect a range given by SCEV.
intersectKnown(getConstantRangeFromSCEV(A, getCtxI()));
// Intersect a range given by LVI.
intersectKnown(getConstantRangeFromLVI(A, getCtxI()));
}
/// Helper function to create MDNode for range metadata.
static MDNode *
getMDNodeForConstantRange(Type *Ty, LLVMContext &Ctx,
const ConstantRange &AssumedConstantRange) {
Metadata *LowAndHigh[] = {ConstantAsMetadata::get(ConstantInt::get(
Ty, AssumedConstantRange.getLower())),
ConstantAsMetadata::get(ConstantInt::get(
Ty, AssumedConstantRange.getUpper()))};
return MDNode::get(Ctx, LowAndHigh);
}
/// Return true if \p Assumed is included in \p KnownRanges.
static bool isBetterRange(const ConstantRange &Assumed, MDNode *KnownRanges) {
if (Assumed.isFullSet())
return false;
if (!KnownRanges)
return true;
// If multiple ranges are annotated in IR, we give up to annotate assumed
// range for now.
// TODO: If there exists a known range which containts assumed range, we
// can say assumed range is better.
if (KnownRanges->getNumOperands() > 2)
return false;
ConstantInt *Lower =
mdconst::extract<ConstantInt>(KnownRanges->getOperand(0));
ConstantInt *Upper =
mdconst::extract<ConstantInt>(KnownRanges->getOperand(1));
ConstantRange Known(Lower->getValue(), Upper->getValue());
return Known.contains(Assumed) && Known != Assumed;
}
/// Helper function to set range metadata.
static bool
setRangeMetadataIfisBetterRange(Instruction *I,
const ConstantRange &AssumedConstantRange) {
auto *OldRangeMD = I->getMetadata(LLVMContext::MD_range);
if (isBetterRange(AssumedConstantRange, OldRangeMD)) {
if (!AssumedConstantRange.isEmptySet()) {
I->setMetadata(LLVMContext::MD_range,
getMDNodeForConstantRange(I->getType(), I->getContext(),
AssumedConstantRange));
return true;
}
}
return false;
}
/// See AbstractAttribute::manifest()
ChangeStatus manifest(Attributor &A) override {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
ConstantRange AssumedConstantRange = getAssumedConstantRange(A);
assert(!AssumedConstantRange.isFullSet() && "Invalid state");
auto &V = getAssociatedValue();
if (!AssumedConstantRange.isEmptySet() &&
!AssumedConstantRange.isSingleElement()) {
if (Instruction *I = dyn_cast<Instruction>(&V))
if (isa<CallInst>(I) || isa<LoadInst>(I))
if (setRangeMetadataIfisBetterRange(I, AssumedConstantRange))
Changed = ChangeStatus::CHANGED;
}
return Changed;
}
};
struct AAValueConstantRangeArgument final : public AAValueConstantRangeImpl {
AAValueConstantRangeArgument(const IRPosition &IRP)
: AAValueConstantRangeImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Use AAArgumentFromCallSiteArguments
IntegerRangeState S(getBitWidth());
clampCallSiteArgumentStates<AAValueConstantRange, IntegerRangeState>(
A, *this, S);
// TODO: If we know we visited all incoming values, thus no are assumed
// dead, we can take the known information from the state T.
return clampStateAndIndicateChange<IntegerRangeState>(this->getState(), S);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_ARG_ATTR(value_range)
}
};
struct AAValueConstantRangeReturned : AAValueConstantRangeImpl {
AAValueConstantRangeReturned(const IRPosition &IRP)
: AAValueConstantRangeImpl(IRP) {}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
// TODO: Use AAReturnedFromReturnedValues
// TODO: If we know we visited all returned values, thus no are assumed
// dead, we can take the known information from the state T.
IntegerRangeState S(getBitWidth());
clampReturnedValueStates<AAValueConstantRange, IntegerRangeState>(A, *this,
S);
return clampStateAndIndicateChange<StateType>(this->getState(), S);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FNRET_ATTR(value_range)
}
};
struct AAValueConstantRangeFloating : AAValueConstantRangeImpl {
AAValueConstantRangeFloating(const IRPosition &IRP)
: AAValueConstantRangeImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
AAValueConstantRange::initialize(A);
Value &V = getAssociatedValue();
if (auto *C = dyn_cast<ConstantInt>(&V)) {
unionAssumed(ConstantRange(C->getValue()));
indicateOptimisticFixpoint();
return;
}
if (isa<UndefValue>(&V)) {
indicateOptimisticFixpoint();
return;
}
if (auto *I = dyn_cast<Instruction>(&V))
if (isa<BinaryOperator>(I) || isa<CmpInst>(I)) {
Value *LHS = I->getOperand(0);
Value *RHS = I->getOperand(1);
if (LHS->getType()->isIntegerTy() && RHS->getType()->isIntegerTy())
return;
}
// If it is a load instruction with range metadata, use it.
if (LoadInst *LI = dyn_cast<LoadInst>(&V))
if (auto *RangeMD = LI->getMetadata(LLVMContext::MD_range)) {
intersectKnown(getConstantRangeFromMetadata(*RangeMD));
return;
}
// Otherwise we give up.
indicatePessimisticFixpoint();
LLVM_DEBUG(dbgs() << "[Attributor][AAValueConstantRange] We give up: "
<< getAssociatedValue());
}
bool calculateBinaryOperator(Attributor &A, BinaryOperator *BinOp,
IntegerRangeState &T, Instruction *CtxI) {
Value *LHS = BinOp->getOperand(0);
Value *RHS = BinOp->getOperand(1);
auto &LHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*LHS));
auto LHSAARange = LHSAA.getAssumedConstantRange(A, CtxI);
auto &RHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*RHS));
auto RHSAARange = RHSAA.getAssumedConstantRange(A, CtxI);
auto AssumedRange = LHSAARange.binaryOp(BinOp->getOpcode(), RHSAARange);
T.unionAssumed(AssumedRange);
// TODO: Track a known state too.
return T.isValidState();
}
bool calculateCmpInst(Attributor &A, CmpInst *CmpI, IntegerRangeState &T,
Instruction *CtxI) {
Value *LHS = CmpI->getOperand(0);
Value *RHS = CmpI->getOperand(1);
auto &LHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*LHS));
auto &RHSAA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(*RHS));
auto LHSAARange = LHSAA.getAssumedConstantRange(A, CtxI);
auto RHSAARange = RHSAA.getAssumedConstantRange(A, CtxI);
// If one of them is empty set, we can't decide.
if (LHSAARange.isEmptySet() || RHSAARange.isEmptySet())
return true;
bool MustTrue = false, MustFalse = false;
auto AllowedRegion =
ConstantRange::makeAllowedICmpRegion(CmpI->getPredicate(), RHSAARange);
auto SatisfyingRegion = ConstantRange::makeSatisfyingICmpRegion(
CmpI->getPredicate(), RHSAARange);
if (AllowedRegion.intersectWith(LHSAARange).isEmptySet())
MustFalse = true;
if (SatisfyingRegion.contains(LHSAARange))
MustTrue = true;
assert((!MustTrue || !MustFalse) &&
"Either MustTrue or MustFalse should be false!");
if (MustTrue)
T.unionAssumed(ConstantRange(APInt(/* numBits */ 1, /* val */ 1)));
else if (MustFalse)
T.unionAssumed(ConstantRange(APInt(/* numBits */ 1, /* val */ 0)));
else
T.unionAssumed(ConstantRange(/* BitWidth */ 1, /* isFullSet */ true));
LLVM_DEBUG(dbgs() << "[AAValueConstantRange] " << *CmpI << " " << LHSAA
<< " " << RHSAA << "\n");
// TODO: Track a known state too.
return T.isValidState();
}
/// See AbstractAttribute::updateImpl(...).
ChangeStatus updateImpl(Attributor &A) override {
Instruction *CtxI = getCtxI();
auto VisitValueCB = [&](Value &V, IntegerRangeState &T,
bool Stripped) -> bool {
Instruction *I = dyn_cast<Instruction>(&V);
if (!I) {
// If the value is not instruction, we query AA to Attributor.
const auto &AA =
A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(V));
// Clamp operator is not used to utilize a program point CtxI.
T.unionAssumed(AA.getAssumedConstantRange(A, CtxI));
return T.isValidState();
}
if (auto *BinOp = dyn_cast<BinaryOperator>(I))
return calculateBinaryOperator(A, BinOp, T, CtxI);
else if (auto *CmpI = dyn_cast<CmpInst>(I))
return calculateCmpInst(A, CmpI, T, CtxI);
else {
// Give up with other instructions.
// TODO: Add other instructions
T.indicatePessimisticFixpoint();
return false;
}
};
IntegerRangeState T(getBitWidth());
if (!genericValueTraversal<AAValueConstantRange, IntegerRangeState>(
A, getIRPosition(), *this, T, VisitValueCB))
return indicatePessimisticFixpoint();
return clampStateAndIndicateChange(getState(), T);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_FLOATING_ATTR(value_range)
}
};
struct AAValueConstantRangeFunction : AAValueConstantRangeImpl {
AAValueConstantRangeFunction(const IRPosition &IRP)
: AAValueConstantRangeImpl(IRP) {}
/// See AbstractAttribute::initialize(...).
ChangeStatus updateImpl(Attributor &A) override {
llvm_unreachable("AAValueConstantRange(Function|CallSite)::updateImpl will "
"not be called");
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_FN_ATTR(value_range) }
};
struct AAValueConstantRangeCallSite : AAValueConstantRangeFunction {
AAValueConstantRangeCallSite(const IRPosition &IRP)
: AAValueConstantRangeFunction(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override { STATS_DECLTRACK_CS_ATTR(value_range) }
};
struct AAValueConstantRangeCallSiteReturned : AAValueConstantRangeReturned {
AAValueConstantRangeCallSiteReturned(const IRPosition &IRP)
: AAValueConstantRangeReturned(IRP) {}
/// See AbstractAttribute::initialize(...).
void initialize(Attributor &A) override {
// If it is a load instruction with range metadata, use the metadata.
if (CallInst *CI = dyn_cast<CallInst>(&getAssociatedValue()))
if (auto *RangeMD = CI->getMetadata(LLVMContext::MD_range))
intersectKnown(getConstantRangeFromMetadata(*RangeMD));
AAValueConstantRangeReturned::initialize(A);
}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSRET_ATTR(value_range)
}
};
struct AAValueConstantRangeCallSiteArgument : AAValueConstantRangeFloating {
AAValueConstantRangeCallSiteArgument(const IRPosition &IRP)
: AAValueConstantRangeFloating(IRP) {}
/// See AbstractAttribute::trackStatistics()
void trackStatistics() const override {
STATS_DECLTRACK_CSARG_ATTR(value_range)
}
};
/// ----------------------------------------------------------------------------
/// Attributor
/// ----------------------------------------------------------------------------
bool Attributor::isAssumedDead(const AbstractAttribute &AA,
const AAIsDead *LivenessAA) {
const Instruction *CtxI = AA.getIRPosition().getCtxI();
if (!CtxI)
return false;
// TODO: Find a good way to utilize fine and coarse grained liveness
// information.
if (!LivenessAA)
LivenessAA =
&getAAFor<AAIsDead>(AA, IRPosition::function(*CtxI->getFunction()),
/* TrackDependence */ false);
// Don't check liveness for AAIsDead.
if (&AA == LivenessAA)
return false;
if (!LivenessAA->isAssumedDead(CtxI))
return false;
// We actually used liveness information so we have to record a dependence.
recordDependence(*LivenessAA, AA, DepClassTy::OPTIONAL);
return true;
}
bool Attributor::checkForAllUses(
const function_ref<bool(const Use &, bool &)> &Pred,
const AbstractAttribute &QueryingAA, const Value &V) {
const IRPosition &IRP = QueryingAA.getIRPosition();
SmallVector<const Use *, 16> Worklist;
SmallPtrSet<const Use *, 16> Visited;
for (const Use &U : V.uses())
Worklist.push_back(&U);
LLVM_DEBUG(dbgs() << "[Attributor] Got " << Worklist.size()
<< " initial uses to check\n");
if (Worklist.empty())
return true;
bool AnyDead = false;
const Function *ScopeFn = IRP.getAnchorScope();
const auto *LivenessAA =
ScopeFn ? &getAAFor<AAIsDead>(QueryingAA, IRPosition::function(*ScopeFn),
/* TrackDependence */ false)
: nullptr;
while (!Worklist.empty()) {
const Use *U = Worklist.pop_back_val();
if (!Visited.insert(U).second)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Check use: " << **U << "\n");
if (Instruction *UserI = dyn_cast<Instruction>(U->getUser()))
if (LivenessAA && LivenessAA->isAssumedDead(UserI)) {
LLVM_DEBUG(dbgs() << "[Attributor] Dead user: " << *UserI << ": "
<< *LivenessAA << "\n");
AnyDead = true;
continue;
}
bool Follow = false;
if (!Pred(*U, Follow))
return false;
if (!Follow)
continue;
for (const Use &UU : U->getUser()->uses())
Worklist.push_back(&UU);
}
if (AnyDead)
recordDependence(*LivenessAA, QueryingAA, DepClassTy::OPTIONAL);
return true;
}
bool Attributor::checkForAllCallSites(
const function_ref<bool(AbstractCallSite)> &Pred,
const AbstractAttribute &QueryingAA, bool RequireAllCallSites) {
// We can try to determine information from
// the call sites. However, this is only possible all call sites are known,
// hence the function has internal linkage.
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction) {
LLVM_DEBUG(dbgs() << "[Attributor] No function associated with " << IRP
<< "\n");
return false;
}
return checkForAllCallSites(Pred, *AssociatedFunction, RequireAllCallSites,
&QueryingAA);
}
bool Attributor::checkForAllCallSites(
const function_ref<bool(AbstractCallSite)> &Pred, const Function &Fn,
bool RequireAllCallSites, const AbstractAttribute *QueryingAA) {
if (RequireAllCallSites && !Fn.hasLocalLinkage()) {
LLVM_DEBUG(
dbgs()
<< "[Attributor] Function " << Fn.getName()
<< " has no internal linkage, hence not all call sites are known\n");
return false;
}
for (const Use &U : Fn.uses()) {
AbstractCallSite ACS(&U);
if (!ACS) {
LLVM_DEBUG(dbgs() << "[Attributor] Function " << Fn.getName()
<< " has non call site use " << *U.get() << " in "
<< *U.getUser() << "\n");
// BlockAddress users are allowed.
if (isa<BlockAddress>(U.getUser()))
continue;
return false;
}
Instruction *I = ACS.getInstruction();
Function *Caller = I->getFunction();
const auto *LivenessAA =
lookupAAFor<AAIsDead>(IRPosition::function(*Caller), QueryingAA,
/* TrackDependence */ false);
// Skip dead calls.
if (LivenessAA && LivenessAA->isAssumedDead(I)) {
// We actually used liveness information so we have to record a
// dependence.
if (QueryingAA)
recordDependence(*LivenessAA, *QueryingAA, DepClassTy::OPTIONAL);
continue;
}
const Use *EffectiveUse =
ACS.isCallbackCall() ? &ACS.getCalleeUseForCallback() : &U;
if (!ACS.isCallee(EffectiveUse)) {
if (!RequireAllCallSites)
continue;
LLVM_DEBUG(dbgs() << "[Attributor] User " << EffectiveUse->getUser()
<< " is an invalid use of " << Fn.getName() << "\n");
return false;
}
if (Pred(ACS))
continue;
LLVM_DEBUG(dbgs() << "[Attributor] Call site callback failed for "
<< *ACS.getInstruction() << "\n");
return false;
}
return true;
}
bool Attributor::checkForAllReturnedValuesAndReturnInsts(
const function_ref<bool(Value &, const SmallSetVector<ReturnInst *, 4> &)>
&Pred,
const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide return instructions we have to have an exact
// definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// If this is a call site query we use the call site specific return values
// and liveness information.
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal = getAAFor<AAReturnedValues>(QueryingAA, QueryIRP);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(Pred);
}
bool Attributor::checkForAllReturnedValues(
const function_ref<bool(Value &)> &Pred,
const AbstractAttribute &QueryingAA) {
const IRPosition &IRP = QueryingAA.getIRPosition();
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &AARetVal = getAAFor<AAReturnedValues>(QueryingAA, QueryIRP);
if (!AARetVal.getState().isValidState())
return false;
return AARetVal.checkForAllReturnedValuesAndReturnInsts(
[&](Value &RV, const SmallSetVector<ReturnInst *, 4> &) {
return Pred(RV);
});
}
static bool
checkForAllInstructionsImpl(InformationCache::OpcodeInstMapTy &OpcodeInstMap,
const function_ref<bool(Instruction &)> &Pred,
const AAIsDead *LivenessAA, bool &AnyDead,
const ArrayRef<unsigned> &Opcodes) {
for (unsigned Opcode : Opcodes) {
for (Instruction *I : OpcodeInstMap[Opcode]) {
// Skip dead instructions.
if (LivenessAA && LivenessAA->isAssumedDead(I)) {
AnyDead = true;
continue;
}
if (!Pred(*I))
return false;
}
}
return true;
}
bool Attributor::checkForAllInstructions(
const llvm::function_ref<bool(Instruction &)> &Pred,
const AbstractAttribute &QueryingAA, const ArrayRef<unsigned> &Opcodes) {
const IRPosition &IRP = QueryingAA.getIRPosition();
// Since we need to provide instructions we have to have an exact definition.
const Function *AssociatedFunction = IRP.getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &LivenessAA =
getAAFor<AAIsDead>(QueryingAA, QueryIRP, /* TrackDependence */ false);
bool AnyDead = false;
auto &OpcodeInstMap =
InfoCache.getOpcodeInstMapForFunction(*AssociatedFunction);
if (!checkForAllInstructionsImpl(OpcodeInstMap, Pred, &LivenessAA, AnyDead,
Opcodes))
return false;
// If we actually used liveness information so we have to record a dependence.
if (AnyDead)
recordDependence(LivenessAA, QueryingAA, DepClassTy::OPTIONAL);
return true;
}
bool Attributor::checkForAllReadWriteInstructions(
const llvm::function_ref<bool(Instruction &)> &Pred,
AbstractAttribute &QueryingAA) {
const Function *AssociatedFunction =
QueryingAA.getIRPosition().getAssociatedFunction();
if (!AssociatedFunction)
return false;
// TODO: use the function scope once we have call site AAReturnedValues.
const IRPosition &QueryIRP = IRPosition::function(*AssociatedFunction);
const auto &LivenessAA =
getAAFor<AAIsDead>(QueryingAA, QueryIRP, /* TrackDependence */ false);
bool AnyDead = false;
for (Instruction *I :
InfoCache.getReadOrWriteInstsForFunction(*AssociatedFunction)) {
// Skip dead instructions.
if (LivenessAA.isAssumedDead(I)) {
AnyDead = true;
continue;
}
if (!Pred(*I))
return false;
}
// If we actually used liveness information so we have to record a dependence.
if (AnyDead)
recordDependence(LivenessAA, QueryingAA, DepClassTy::OPTIONAL);
return true;
}
ChangeStatus Attributor::run(Module &M) {
LLVM_DEBUG(dbgs() << "[Attributor] Identified and initialized "
<< AllAbstractAttributes.size()
<< " abstract attributes.\n");
// Now that all abstract attributes are collected and initialized we start
// the abstract analysis.
unsigned IterationCounter = 1;
SmallVector<AbstractAttribute *, 64> ChangedAAs;
SetVector<AbstractAttribute *> Worklist, InvalidAAs;
Worklist.insert(AllAbstractAttributes.begin(), AllAbstractAttributes.end());
bool RecomputeDependences = false;
do {
// Remember the size to determine new attributes.
size_t NumAAs = AllAbstractAttributes.size();
LLVM_DEBUG(dbgs() << "\n\n[Attributor] #Iteration: " << IterationCounter
<< ", Worklist size: " << Worklist.size() << "\n");
// For invalid AAs we can fix dependent AAs that have a required dependence,
// thereby folding long dependence chains in a single step without the need
// to run updates.
for (unsigned u = 0; u < InvalidAAs.size(); ++u) {
AbstractAttribute *InvalidAA = InvalidAAs[u];
auto &QuerriedAAs = QueryMap[InvalidAA];
LLVM_DEBUG(dbgs() << "[Attributor] InvalidAA: " << *InvalidAA << " has "
<< QuerriedAAs.RequiredAAs.size() << "/"
<< QuerriedAAs.OptionalAAs.size()
<< " required/optional dependences\n");
for (AbstractAttribute *DepOnInvalidAA : QuerriedAAs.RequiredAAs) {
AbstractState &DOIAAState = DepOnInvalidAA->getState();
DOIAAState.indicatePessimisticFixpoint();
++NumAttributesFixedDueToRequiredDependences;
assert(DOIAAState.isAtFixpoint() && "Expected fixpoint state!");
if (!DOIAAState.isValidState())
InvalidAAs.insert(DepOnInvalidAA);
}
if (!RecomputeDependences)
Worklist.insert(QuerriedAAs.OptionalAAs.begin(),
QuerriedAAs.OptionalAAs.end());
}
// If dependences (=QueryMap) are recomputed we have to look at all abstract
// attributes again, regardless of what changed in the last iteration.
if (RecomputeDependences) {
LLVM_DEBUG(
dbgs() << "[Attributor] Run all AAs to recompute dependences\n");
QueryMap.clear();
ChangedAAs.clear();
Worklist.insert(AllAbstractAttributes.begin(),
AllAbstractAttributes.end());
}
// Add all abstract attributes that are potentially dependent on one that
// changed to the work list.
for (AbstractAttribute *ChangedAA : ChangedAAs) {
auto &QuerriedAAs = QueryMap[ChangedAA];
Worklist.insert(QuerriedAAs.OptionalAAs.begin(),
QuerriedAAs.OptionalAAs.end());
Worklist.insert(QuerriedAAs.RequiredAAs.begin(),
QuerriedAAs.RequiredAAs.end());
}
LLVM_DEBUG(dbgs() << "[Attributor] #Iteration: " << IterationCounter
<< ", Worklist+Dependent size: " << Worklist.size()
<< "\n");
// Reset the changed and invalid set.
ChangedAAs.clear();
InvalidAAs.clear();
// Update all abstract attribute in the work list and record the ones that
// changed.
for (AbstractAttribute *AA : Worklist)
if (!AA->getState().isAtFixpoint() && !isAssumedDead(*AA, nullptr)) {
QueriedNonFixAA = false;
if (AA->update(*this) == ChangeStatus::CHANGED) {
ChangedAAs.push_back(AA);
if (!AA->getState().isValidState())
InvalidAAs.insert(AA);
} else if (!QueriedNonFixAA) {
// If the attribute did not query any non-fix information, the state
// will not change and we can indicate that right away.
AA->getState().indicateOptimisticFixpoint();
}
}
// Check if we recompute the dependences in the next iteration.
RecomputeDependences = (DepRecomputeInterval > 0 &&
IterationCounter % DepRecomputeInterval == 0);
// Add attributes to the changed set if they have been created in the last
// iteration.
ChangedAAs.append(AllAbstractAttributes.begin() + NumAAs,
AllAbstractAttributes.end());
// Reset the work list and repopulate with the changed abstract attributes.
// Note that dependent ones are added above.
Worklist.clear();
Worklist.insert(ChangedAAs.begin(), ChangedAAs.end());
} while (!Worklist.empty() && (IterationCounter++ < MaxFixpointIterations ||
VerifyMaxFixpointIterations));
LLVM_DEBUG(dbgs() << "\n[Attributor] Fixpoint iteration done after: "
<< IterationCounter << "/" << MaxFixpointIterations
<< " iterations\n");
size_t NumFinalAAs = AllAbstractAttributes.size();
// Reset abstract arguments not settled in a sound fixpoint by now. This
// happens when we stopped the fixpoint iteration early. Note that only the
// ones marked as "changed" *and* the ones transitively depending on them
// need to be reverted to a pessimistic state. Others might not be in a
// fixpoint state but we can use the optimistic results for them anyway.
SmallPtrSet<AbstractAttribute *, 32> Visited;
for (unsigned u = 0; u < ChangedAAs.size(); u++) {
AbstractAttribute *ChangedAA = ChangedAAs[u];
if (!Visited.insert(ChangedAA).second)
continue;
AbstractState &State = ChangedAA->getState();
if (!State.isAtFixpoint()) {
State.indicatePessimisticFixpoint();
NumAttributesTimedOut++;
}
auto &QuerriedAAs = QueryMap[ChangedAA];
ChangedAAs.append(QuerriedAAs.OptionalAAs.begin(),
QuerriedAAs.OptionalAAs.end());
ChangedAAs.append(QuerriedAAs.RequiredAAs.begin(),
QuerriedAAs.RequiredAAs.end());
}
LLVM_DEBUG({
if (!Visited.empty())
dbgs() << "\n[Attributor] Finalized " << Visited.size()
<< " abstract attributes.\n";
});
unsigned NumManifested = 0;
unsigned NumAtFixpoint = 0;
ChangeStatus ManifestChange = ChangeStatus::UNCHANGED;
for (AbstractAttribute *AA : AllAbstractAttributes) {
AbstractState &State = AA->getState();
// If there is not already a fixpoint reached, we can now take the
// optimistic state. This is correct because we enforced a pessimistic one
// on abstract attributes that were transitively dependent on a changed one
// already above.
if (!State.isAtFixpoint())
State.indicateOptimisticFixpoint();
// If the state is invalid, we do not try to manifest it.
if (!State.isValidState())
continue;
// Skip dead code.
if (isAssumedDead(*AA, nullptr))
continue;
// Manifest the state and record if we changed the IR.
ChangeStatus LocalChange = AA->manifest(*this);
if (LocalChange == ChangeStatus::CHANGED && AreStatisticsEnabled())
AA->trackStatistics();
ManifestChange = ManifestChange | LocalChange;
NumAtFixpoint++;
NumManifested += (LocalChange == ChangeStatus::CHANGED);
}
(void)NumManifested;
(void)NumAtFixpoint;
LLVM_DEBUG(dbgs() << "\n[Attributor] Manifested " << NumManifested
<< " arguments while " << NumAtFixpoint
<< " were in a valid fixpoint state\n");
NumAttributesManifested += NumManifested;
NumAttributesValidFixpoint += NumAtFixpoint;
(void)NumFinalAAs;
assert(
NumFinalAAs == AllAbstractAttributes.size() &&
"Expected the final number of abstract attributes to remain unchanged!");
// Delete stuff at the end to avoid invalid references and a nice order.
{
LLVM_DEBUG(dbgs() << "\n[Attributor] Delete at least "
<< ToBeDeletedFunctions.size() << " functions and "
<< ToBeDeletedBlocks.size() << " blocks and "
<< ToBeDeletedInsts.size() << " instructions and "
<< ToBeChangedUses.size() << " uses\n");
SmallVector<Instruction *, 32> DeadInsts;
SmallVector<Instruction *, 32> TerminatorsToFold;
for (auto &It : ToBeChangedUses) {
Use *U = It.first;
Value *NewV = It.second;
Value *OldV = U->get();
LLVM_DEBUG(dbgs() << "Use " << *NewV << " in " << *U->getUser()
<< " instead of " << *OldV << "\n");
U->set(NewV);
if (Instruction *I = dyn_cast<Instruction>(OldV))
if (!isa<PHINode>(I) && !ToBeDeletedInsts.count(I) &&
isInstructionTriviallyDead(I)) {
DeadInsts.push_back(I);
}
if (isa<Constant>(NewV) && isa<BranchInst>(U->getUser())) {
Instruction *UserI = cast<Instruction>(U->getUser());
if (isa<UndefValue>(NewV)) {
ToBeChangedToUnreachableInsts.insert(UserI);
} else {
TerminatorsToFold.push_back(UserI);
}
}
}
for (auto &V : InvokeWithDeadSuccessor)
if (InvokeInst *II = dyn_cast_or_null<InvokeInst>(V)) {
bool UnwindBBIsDead = II->hasFnAttr(Attribute::NoUnwind);
bool NormalBBIsDead = II->hasFnAttr(Attribute::NoReturn);
bool Invoke2CallAllowed =
!AAIsDeadFunction::mayCatchAsynchronousExceptions(
*II->getFunction());
assert((UnwindBBIsDead || NormalBBIsDead) &&
"Invoke does not have dead successors!");
BasicBlock *BB = II->getParent();
BasicBlock *NormalDestBB = II->getNormalDest();
if (UnwindBBIsDead) {
Instruction *NormalNextIP = &NormalDestBB->front();
if (Invoke2CallAllowed) {
changeToCall(II);
NormalNextIP = BB->getTerminator();
}
if (NormalBBIsDead)
ToBeChangedToUnreachableInsts.insert(NormalNextIP);
} else {
assert(NormalBBIsDead && "Broken invariant!");
if (!NormalDestBB->getUniquePredecessor())
NormalDestBB = SplitBlockPredecessors(NormalDestBB, {BB}, ".dead");
ToBeChangedToUnreachableInsts.insert(&NormalDestBB->front());
}
}
for (auto &V : ToBeChangedToUnreachableInsts)
if (Instruction *I = dyn_cast_or_null<Instruction>(V))
changeToUnreachable(I, /* UseLLVMTrap */ false);
for (Instruction *I : TerminatorsToFold)
ConstantFoldTerminator(I->getParent());
for (Instruction *I : ToBeDeletedInsts) {
I->replaceAllUsesWith(UndefValue::get(I->getType()));
if (!isa<PHINode>(I) && isInstructionTriviallyDead(I))
DeadInsts.push_back(I);
else
I->eraseFromParent();
}
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts);
if (unsigned NumDeadBlocks = ToBeDeletedBlocks.size()) {
SmallVector<BasicBlock *, 8> ToBeDeletedBBs;
ToBeDeletedBBs.reserve(NumDeadBlocks);
ToBeDeletedBBs.append(ToBeDeletedBlocks.begin(), ToBeDeletedBlocks.end());
// Actually we do not delete the blocks but squash them into a single
// unreachable but untangling branches that jump here is something we need
// to do in a more generic way.
DetatchDeadBlocks(ToBeDeletedBBs, nullptr);
STATS_DECL(AAIsDead, BasicBlock, "Number of dead basic blocks deleted.");
BUILD_STAT_NAME(AAIsDead, BasicBlock) += ToBeDeletedBlocks.size();
}
// Identify dead internal functions and delete them. This happens outside
// the other fixpoint analysis as we might treat potentially dead functions
// as live to lower the number of iterations. If they happen to be dead, the
// below fixpoint loop will identify and eliminate them.
SmallVector<Function *, 8> InternalFns;
for (Function &F : M)
if (F.hasLocalLinkage())
InternalFns.push_back(&F);
bool FoundDeadFn = true;
while (FoundDeadFn) {
FoundDeadFn = false;
for (unsigned u = 0, e = InternalFns.size(); u < e; ++u) {
Function *F = InternalFns[u];
if (!F)
continue;
if (!checkForAllCallSites(
[this](AbstractCallSite ACS) {
return ToBeDeletedFunctions.count(
ACS.getInstruction()->getFunction());
},
*F, true, nullptr))
continue;
ToBeDeletedFunctions.insert(F);
InternalFns[u] = nullptr;
FoundDeadFn = true;
}
}
}
STATS_DECL(AAIsDead, Function, "Number of dead functions deleted.");
BUILD_STAT_NAME(AAIsDead, Function) += ToBeDeletedFunctions.size();
// Rewrite the functions as requested during manifest.
ManifestChange = ManifestChange | rewriteFunctionSignatures();
for (Function *Fn : ToBeDeletedFunctions) {
Fn->deleteBody();
Fn->replaceAllUsesWith(UndefValue::get(Fn->getType()));
Fn->eraseFromParent();
}
if (VerifyMaxFixpointIterations &&
IterationCounter != MaxFixpointIterations) {
errs() << "\n[Attributor] Fixpoint iteration done after: "
<< IterationCounter << "/" << MaxFixpointIterations
<< " iterations\n";
llvm_unreachable("The fixpoint was not reached with exactly the number of "
"specified iterations!");
}
return ManifestChange;
}
bool Attributor::registerFunctionSignatureRewrite(
Argument &Arg, ArrayRef<Type *> ReplacementTypes,
ArgumentReplacementInfo::CalleeRepairCBTy &&CalleeRepairCB,
ArgumentReplacementInfo::ACSRepairCBTy &&ACSRepairCB) {
auto CallSiteCanBeChanged = [](AbstractCallSite ACS) {
// Forbid must-tail calls for now.
return !ACS.isCallbackCall() && !ACS.getCallSite().isMustTailCall();
};
Function *Fn = Arg.getParent();
// Avoid var-arg functions for now.
if (Fn->isVarArg()) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite var-args functions\n");
return false;
}
// Avoid functions with complicated argument passing semantics.
AttributeList FnAttributeList = Fn->getAttributes();
if (FnAttributeList.hasAttrSomewhere(Attribute::Nest) ||
FnAttributeList.hasAttrSomewhere(Attribute::StructRet) ||
FnAttributeList.hasAttrSomewhere(Attribute::InAlloca)) {
LLVM_DEBUG(
dbgs() << "[Attributor] Cannot rewrite due to complex attribute\n");
return false;
}
// Avoid callbacks for now.
if (!checkForAllCallSites(CallSiteCanBeChanged, *Fn, true, nullptr)) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite all call sites\n");
return false;
}
auto InstPred = [](Instruction &I) {
if (auto *CI = dyn_cast<CallInst>(&I))
return !CI->isMustTailCall();
return true;
};
// Forbid must-tail calls for now.
// TODO:
bool AnyDead;
auto &OpcodeInstMap = InfoCache.getOpcodeInstMapForFunction(*Fn);
if (!checkForAllInstructionsImpl(OpcodeInstMap, InstPred, nullptr, AnyDead,
{Instruction::Call})) {
LLVM_DEBUG(dbgs() << "[Attributor] Cannot rewrite due to instructions\n");
return false;
}
SmallVectorImpl<ArgumentReplacementInfo *> &ARIs = ArgumentReplacementMap[Fn];
if (ARIs.size() == 0)
ARIs.resize(Fn->arg_size());
// If we have a replacement already with less than or equal new arguments,
// ignore this request.
ArgumentReplacementInfo *&ARI = ARIs[Arg.getArgNo()];
if (ARI && ARI->getNumReplacementArgs() <= ReplacementTypes.size()) {
LLVM_DEBUG(dbgs() << "[Attributor] Existing rewrite is preferred\n");
return false;
}
// If we have a replacement already but we like the new one better, delete
// the old.
if (ARI)
delete ARI;
// Remember the replacement.
ARI = new ArgumentReplacementInfo(*this, Arg, ReplacementTypes,
std::move(CalleeRepairCB),
std::move(ACSRepairCB));
return true;
}
ChangeStatus Attributor::rewriteFunctionSignatures() {
ChangeStatus Changed = ChangeStatus::UNCHANGED;
for (auto &It : ArgumentReplacementMap) {
Function *OldFn = It.getFirst();
// Deleted functions do not require rewrites.
if (ToBeDeletedFunctions.count(OldFn))
continue;
const SmallVectorImpl<ArgumentReplacementInfo *> &ARIs = It.getSecond();
assert(ARIs.size() == OldFn->arg_size() && "Inconsistent state!");
SmallVector<Type *, 16> NewArgumentTypes;
SmallVector<AttributeSet, 16> NewArgumentAttributes;
// Collect replacement argument types and copy over existing attributes.
AttributeList OldFnAttributeList = OldFn->getAttributes();
for (Argument &Arg : OldFn->args()) {
if (ArgumentReplacementInfo *ARI = ARIs[Arg.getArgNo()]) {
NewArgumentTypes.append(ARI->ReplacementTypes.begin(),
ARI->ReplacementTypes.end());
NewArgumentAttributes.append(ARI->getNumReplacementArgs(),
AttributeSet());
} else {
NewArgumentTypes.push_back(Arg.getType());
NewArgumentAttributes.push_back(
OldFnAttributeList.getParamAttributes(Arg.getArgNo()));
}
}
FunctionType *OldFnTy = OldFn->getFunctionType();
Type *RetTy = OldFnTy->getReturnType();
// Construct the new function type using the new arguments types.
FunctionType *NewFnTy =
FunctionType::get(RetTy, NewArgumentTypes, OldFnTy->isVarArg());
LLVM_DEBUG(dbgs() << "[Attributor] Function rewrite '" << OldFn->getName()
<< "' from " << *OldFn->getFunctionType() << " to "
<< *NewFnTy << "\n");
// Create the new function body and insert it into the module.
Function *NewFn = Function::Create(NewFnTy, OldFn->getLinkage(),
OldFn->getAddressSpace(), "");
OldFn->getParent()->getFunctionList().insert(OldFn->getIterator(), NewFn);
NewFn->takeName(OldFn);
NewFn->copyAttributesFrom(OldFn);
// Patch the pointer to LLVM function in debug info descriptor.
NewFn->setSubprogram(OldFn->getSubprogram());
OldFn->setSubprogram(nullptr);
// Recompute the parameter attributes list based on the new arguments for
// the function.
LLVMContext &Ctx = OldFn->getContext();
NewFn->setAttributes(AttributeList::get(
Ctx, OldFnAttributeList.getFnAttributes(),
OldFnAttributeList.getRetAttributes(), NewArgumentAttributes));
// Since we have now created the new function, splice the body of the old
// function right into the new function, leaving the old rotting hulk of the
// function empty.
NewFn->getBasicBlockList().splice(NewFn->begin(),
OldFn->getBasicBlockList());
// Set of all "call-like" instructions that invoke the old function mapped
// to their new replacements.
SmallVector<std::pair<CallBase *, CallBase *>, 8> CallSitePairs;
// Callback to create a new "call-like" instruction for a given one.
auto CallSiteReplacementCreator = [&](AbstractCallSite ACS) {
CallBase *OldCB = cast<CallBase>(ACS.getInstruction());
const AttributeList &OldCallAttributeList = OldCB->getAttributes();
// Collect the new argument operands for the replacement call site.
SmallVector<Value *, 16> NewArgOperands;
SmallVector<AttributeSet, 16> NewArgOperandAttributes;
for (unsigned OldArgNum = 0; OldArgNum < ARIs.size(); ++OldArgNum) {
unsigned NewFirstArgNum = NewArgOperands.size();
(void)NewFirstArgNum; // only used inside assert.
if (ArgumentReplacementInfo *ARI = ARIs[OldArgNum]) {
if (ARI->ACSRepairCB)
ARI->ACSRepairCB(*ARI, ACS, NewArgOperands);
assert(ARI->getNumReplacementArgs() + NewFirstArgNum ==
NewArgOperands.size() &&
"ACS repair callback did not provide as many operand as new "
"types were registered!");
// TODO: Exose the attribute set to the ACS repair callback
NewArgOperandAttributes.append(ARI->ReplacementTypes.size(),
AttributeSet());
} else {
NewArgOperands.push_back(ACS.getCallArgOperand(OldArgNum));
NewArgOperandAttributes.push_back(
OldCallAttributeList.getParamAttributes(OldArgNum));
}
}
assert(NewArgOperands.size() == NewArgOperandAttributes.size() &&
"Mismatch # argument operands vs. # argument operand attributes!");
assert(NewArgOperands.size() == NewFn->arg_size() &&
"Mismatch # argument operands vs. # function arguments!");
SmallVector<OperandBundleDef, 4> OperandBundleDefs;
OldCB->getOperandBundlesAsDefs(OperandBundleDefs);
// Create a new call or invoke instruction to replace the old one.
CallBase *NewCB;
if (InvokeInst *II = dyn_cast<InvokeInst>(OldCB)) {
NewCB =
InvokeInst::Create(NewFn, II->getNormalDest(), II->getUnwindDest(),
NewArgOperands, OperandBundleDefs, "", OldCB);
} else {
auto *NewCI = CallInst::Create(NewFn, NewArgOperands, OperandBundleDefs,
"", OldCB);
NewCI->setTailCallKind(cast<CallInst>(OldCB)->getTailCallKind());
NewCB = NewCI;
}
// Copy over various properties and the new attributes.
uint64_t W;
if (OldCB->extractProfTotalWeight(W))
NewCB->setProfWeight(W);
NewCB->setCallingConv(OldCB->getCallingConv());
NewCB->setDebugLoc(OldCB->getDebugLoc());
NewCB->takeName(OldCB);
NewCB->setAttributes(AttributeList::get(
Ctx, OldCallAttributeList.getFnAttributes(),
OldCallAttributeList.getRetAttributes(), NewArgOperandAttributes));
CallSitePairs.push_back({OldCB, NewCB});
return true;
};
// Use the CallSiteReplacementCreator to create replacement call sites.
bool Success =
checkForAllCallSites(CallSiteReplacementCreator, *OldFn, true, nullptr);
(void)Success;
assert(Success && "Assumed call site replacement to succeed!");
// Rewire the arguments.
auto OldFnArgIt = OldFn->arg_begin();
auto NewFnArgIt = NewFn->arg_begin();
for (unsigned OldArgNum = 0; OldArgNum < ARIs.size();
++OldArgNum, ++OldFnArgIt) {
if (ArgumentReplacementInfo *ARI = ARIs[OldArgNum]) {
if (ARI->CalleeRepairCB)
ARI->CalleeRepairCB(*ARI, *NewFn, NewFnArgIt);
NewFnArgIt += ARI->ReplacementTypes.size();
} else {
NewFnArgIt->takeName(&*OldFnArgIt);
OldFnArgIt->replaceAllUsesWith(&*NewFnArgIt);
++NewFnArgIt;
}
}
// Eliminate the instructions *after* we visited all of them.
for (auto &CallSitePair : CallSitePairs) {
CallBase &OldCB = *CallSitePair.first;
CallBase &NewCB = *CallSitePair.second;
OldCB.replaceAllUsesWith(&NewCB);
OldCB.eraseFromParent();
}
ToBeDeletedFunctions.insert(OldFn);
Changed = ChangeStatus::CHANGED;
}
return Changed;
}
void Attributor::initializeInformationCache(Function &F) {
// Walk all instructions to find interesting instructions that might be
// queried by abstract attributes during their initialization or update.
// This has to happen before we create attributes.
auto &ReadOrWriteInsts = InfoCache.FuncRWInstsMap[&F];
auto &InstOpcodeMap = InfoCache.FuncInstOpcodeMap[&F];
for (Instruction &I : instructions(&F)) {
bool IsInterestingOpcode = false;
// To allow easy access to all instructions in a function with a given
// opcode we store them in the InfoCache. As not all opcodes are interesting
// to concrete attributes we only cache the ones that are as identified in
// the following switch.
// Note: There are no concrete attributes now so this is initially empty.
switch (I.getOpcode()) {
default:
assert((!ImmutableCallSite(&I)) && (!isa<CallBase>(&I)) &&
"New call site/base instruction type needs to be known int the "
"Attributor.");
break;
case Instruction::Load:
// The alignment of a pointer is interesting for loads.
case Instruction::Store:
// The alignment of a pointer is interesting for stores.
case Instruction::Call:
case Instruction::CallBr:
case Instruction::Invoke:
case Instruction::CleanupRet:
case Instruction::CatchSwitch:
case Instruction::AtomicRMW:
case Instruction::AtomicCmpXchg:
case Instruction::Br:
case Instruction::Resume:
case Instruction::Ret:
IsInterestingOpcode = true;
}
if (IsInterestingOpcode)
InstOpcodeMap[I.getOpcode()].push_back(&I);
if (I.mayReadOrWriteMemory())
ReadOrWriteInsts.push_back(&I);
}
}
void Attributor::recordDependence(const AbstractAttribute &FromAA,
const AbstractAttribute &ToAA,
DepClassTy DepClass) {
if (FromAA.getState().isAtFixpoint())
return;
if (DepClass == DepClassTy::REQUIRED)
QueryMap[&FromAA].RequiredAAs.insert(
const_cast<AbstractAttribute *>(&ToAA));
else
QueryMap[&FromAA].OptionalAAs.insert(
const_cast<AbstractAttribute *>(&ToAA));
QueriedNonFixAA = true;
}
void Attributor::identifyDefaultAbstractAttributes(Function &F) {
if (!VisitedFunctions.insert(&F).second)
return;
if (F.isDeclaration())
return;
IRPosition FPos = IRPosition::function(F);
// Check for dead BasicBlocks in every function.
// We need dead instruction detection because we do not want to deal with
// broken IR in which SSA rules do not apply.
getOrCreateAAFor<AAIsDead>(FPos);
// Every function might be "will-return".
getOrCreateAAFor<AAWillReturn>(FPos);
// Every function might contain instructions that cause "undefined behavior".
getOrCreateAAFor<AAUndefinedBehavior>(FPos);
// Every function can be nounwind.
getOrCreateAAFor<AANoUnwind>(FPos);
// Every function might be marked "nosync"
getOrCreateAAFor<AANoSync>(FPos);
// Every function might be "no-free".
getOrCreateAAFor<AANoFree>(FPos);
// Every function might be "no-return".
getOrCreateAAFor<AANoReturn>(FPos);
// Every function might be "no-recurse".
getOrCreateAAFor<AANoRecurse>(FPos);
// Every function might be "readnone/readonly/writeonly/...".
getOrCreateAAFor<AAMemoryBehavior>(FPos);
// Every function might be applicable for Heap-To-Stack conversion.
if (EnableHeapToStack)
getOrCreateAAFor<AAHeapToStack>(FPos);
// Return attributes are only appropriate if the return type is non void.
Type *ReturnType = F.getReturnType();
if (!ReturnType->isVoidTy()) {
// Argument attribute "returned" --- Create only one per function even
// though it is an argument attribute.
getOrCreateAAFor<AAReturnedValues>(FPos);
IRPosition RetPos = IRPosition::returned(F);
// Every returned value might be dead.
getOrCreateAAFor<AAIsDead>(RetPos);
// Every function might be simplified.
getOrCreateAAFor<AAValueSimplify>(RetPos);
if (ReturnType->isPointerTy()) {
// Every function with pointer return type might be marked align.
getOrCreateAAFor<AAAlign>(RetPos);
// Every function with pointer return type might be marked nonnull.
getOrCreateAAFor<AANonNull>(RetPos);
// Every function with pointer return type might be marked noalias.
getOrCreateAAFor<AANoAlias>(RetPos);
// Every function with pointer return type might be marked
// dereferenceable.
getOrCreateAAFor<AADereferenceable>(RetPos);
}
}
for (Argument &Arg : F.args()) {
IRPosition ArgPos = IRPosition::argument(Arg);
// Every argument might be simplified.
getOrCreateAAFor<AAValueSimplify>(ArgPos);
if (Arg.getType()->isPointerTy()) {
// Every argument with pointer type might be marked nonnull.
getOrCreateAAFor<AANonNull>(ArgPos);
// Every argument with pointer type might be marked noalias.
getOrCreateAAFor<AANoAlias>(ArgPos);
// Every argument with pointer type might be marked dereferenceable.
getOrCreateAAFor<AADereferenceable>(ArgPos);
// Every argument with pointer type might be marked align.
getOrCreateAAFor<AAAlign>(ArgPos);
// Every argument with pointer type might be marked nocapture.
getOrCreateAAFor<AANoCapture>(ArgPos);
// Every argument with pointer type might be marked
// "readnone/readonly/writeonly/..."
getOrCreateAAFor<AAMemoryBehavior>(ArgPos);
// Every argument with pointer type might be marked nofree.
getOrCreateAAFor<AANoFree>(ArgPos);
}
}
auto CallSitePred = [&](Instruction &I) -> bool {
CallSite CS(&I);
if (Function *Callee = CS.getCalledFunction()) {
// Skip declerations except if annotations on their call sites were
// explicitly requested.
if (!AnnotateDeclarationCallSites && Callee->isDeclaration() &&
!Callee->hasMetadata(LLVMContext::MD_callback))
return true;
if (!Callee->getReturnType()->isVoidTy() && !CS->use_empty()) {
IRPosition CSRetPos = IRPosition::callsite_returned(CS);
// Call site return values might be dead.
getOrCreateAAFor<AAIsDead>(CSRetPos);
// Call site return integer values might be limited by a constant range.
if (Callee->getReturnType()->isIntegerTy()) {
getOrCreateAAFor<AAValueConstantRange>(CSRetPos);
}
}
for (int i = 0, e = CS.getNumArgOperands(); i < e; i++) {
IRPosition CSArgPos = IRPosition::callsite_argument(CS, i);
// Every call site argument might be dead.
getOrCreateAAFor<AAIsDead>(CSArgPos);
// Call site argument might be simplified.
getOrCreateAAFor<AAValueSimplify>(CSArgPos);
if (!CS.getArgument(i)->getType()->isPointerTy())
continue;
// Call site argument attribute "non-null".
getOrCreateAAFor<AANonNull>(CSArgPos);
// Call site argument attribute "no-alias".
getOrCreateAAFor<AANoAlias>(CSArgPos);
// Call site argument attribute "dereferenceable".
getOrCreateAAFor<AADereferenceable>(CSArgPos);
// Call site argument attribute "align".
getOrCreateAAFor<AAAlign>(CSArgPos);
// Call site argument attribute
// "readnone/readonly/writeonly/..."
getOrCreateAAFor<AAMemoryBehavior>(CSArgPos);
// Call site argument attribute "nofree".
getOrCreateAAFor<AANoFree>(CSArgPos);
}
}
return true;
};
auto &OpcodeInstMap = InfoCache.getOpcodeInstMapForFunction(F);
bool Success, AnyDead = false;
Success = checkForAllInstructionsImpl(
OpcodeInstMap, CallSitePred, nullptr, AnyDead,
{(unsigned)Instruction::Invoke, (unsigned)Instruction::CallBr,
(unsigned)Instruction::Call});
(void)Success;
assert(Success && !AnyDead && "Expected the check call to be successful!");
auto LoadStorePred = [&](Instruction &I) -> bool {
if (isa<LoadInst>(I))
getOrCreateAAFor<AAAlign>(
IRPosition::value(*cast<LoadInst>(I).getPointerOperand()));
else
getOrCreateAAFor<AAAlign>(
IRPosition::value(*cast<StoreInst>(I).getPointerOperand()));
return true;
};
Success = checkForAllInstructionsImpl(
OpcodeInstMap, LoadStorePred, nullptr, AnyDead,
{(unsigned)Instruction::Load, (unsigned)Instruction::Store});
(void)Success;
assert(Success && !AnyDead && "Expected the check call to be successful!");
}
/// Helpers to ease debugging through output streams and print calls.
///
///{
raw_ostream &llvm::operator<<(raw_ostream &OS, ChangeStatus S) {
return OS << (S == ChangeStatus::CHANGED ? "changed" : "unchanged");
}
raw_ostream &llvm::operator<<(raw_ostream &OS, IRPosition::Kind AP) {
switch (AP) {
case IRPosition::IRP_INVALID:
return OS << "inv";
case IRPosition::IRP_FLOAT:
return OS << "flt";
case IRPosition::IRP_RETURNED:
return OS << "fn_ret";
case IRPosition::IRP_CALL_SITE_RETURNED:
return OS << "cs_ret";
case IRPosition::IRP_FUNCTION:
return OS << "fn";
case IRPosition::IRP_CALL_SITE:
return OS << "cs";
case IRPosition::IRP_ARGUMENT:
return OS << "arg";
case IRPosition::IRP_CALL_SITE_ARGUMENT:
return OS << "cs_arg";
}
llvm_unreachable("Unknown attribute position!");
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const IRPosition &Pos) {
const Value &AV = Pos.getAssociatedValue();
return OS << "{" << Pos.getPositionKind() << ":" << AV.getName() << " ["
<< Pos.getAnchorValue().getName() << "@" << Pos.getArgNo() << "]}";
}
template <typename base_ty, base_ty BestState, base_ty WorstState>
raw_ostream &
llvm::operator<<(raw_ostream &OS,
const IntegerStateBase<base_ty, BestState, WorstState> &S) {
return OS << "(" << S.getKnown() << "-" << S.getAssumed() << ")"
<< static_cast<const AbstractState &>(S);
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const IntegerRangeState &S) {
OS << "range-state(" << S.getBitWidth() << ")<";
S.getKnown().print(OS);
OS << " / ";
S.getAssumed().print(OS);
OS << ">";
return OS << static_cast<const AbstractState &>(S);
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const AbstractState &S) {
return OS << (!S.isValidState() ? "top" : (S.isAtFixpoint() ? "fix" : ""));
}
raw_ostream &llvm::operator<<(raw_ostream &OS, const AbstractAttribute &AA) {
AA.print(OS);
return OS;
}
void AbstractAttribute::print(raw_ostream &OS) const {
OS << "[P: " << getIRPosition() << "][" << getAsStr() << "][S: " << getState()
<< "]";
}
///}
/// ----------------------------------------------------------------------------
/// Pass (Manager) Boilerplate
/// ----------------------------------------------------------------------------
static bool runAttributorOnModule(Module &M, AnalysisGetter &AG) {
if (DisableAttributor)
return false;
LLVM_DEBUG(dbgs() << "[Attributor] Run on module with " << M.size()
<< " functions.\n");
// Create an Attributor and initially empty information cache that is filled
// while we identify default attribute opportunities.
InformationCache InfoCache(M, AG);
Attributor A(InfoCache, DepRecInterval);
for (Function &F : M)
A.initializeInformationCache(F);
for (Function &F : M) {
if (F.hasExactDefinition())
NumFnWithExactDefinition++;
else
NumFnWithoutExactDefinition++;
// We look at internal functions only on-demand but if any use is not a
// direct call, we have to do it eagerly.
if (F.hasLocalLinkage()) {
if (llvm::all_of(F.uses(), [](const Use &U) {
return ImmutableCallSite(U.getUser()) &&
ImmutableCallSite(U.getUser()).isCallee(&U);
}))
continue;
}
// Populate the Attributor with abstract attribute opportunities in the
// function and the information cache with IR information.
A.identifyDefaultAbstractAttributes(F);
}
bool Changed = A.run(M) == ChangeStatus::CHANGED;
assert(!verifyModule(M, &errs()) && "Module verification failed!");
return Changed;
}
PreservedAnalyses AttributorPass::run(Module &M, ModuleAnalysisManager &AM) {
AnalysisGetter AG(AM);
if (runAttributorOnModule(M, AG)) {
// FIXME: Think about passes we will preserve and add them here.
return PreservedAnalyses::none();
}
return PreservedAnalyses::all();
}
namespace {
struct AttributorLegacyPass : public ModulePass {
static char ID;
AttributorLegacyPass() : ModulePass(ID) {
initializeAttributorLegacyPassPass(*PassRegistry::getPassRegistry());
}
bool runOnModule(Module &M) override {
if (skipModule(M))
return false;
AnalysisGetter AG;
return runAttributorOnModule(M, AG);
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
// FIXME: Think about passes we will preserve and add them here.
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
};
} // end anonymous namespace
Pass *llvm::createAttributorLegacyPass() { return new AttributorLegacyPass(); }
char AttributorLegacyPass::ID = 0;
const char AAReturnedValues::ID = 0;
const char AANoUnwind::ID = 0;
const char AANoSync::ID = 0;
const char AANoFree::ID = 0;
const char AANonNull::ID = 0;
const char AANoRecurse::ID = 0;
const char AAWillReturn::ID = 0;
const char AAUndefinedBehavior::ID = 0;
const char AANoAlias::ID = 0;
const char AAReachability::ID = 0;
const char AANoReturn::ID = 0;
const char AAIsDead::ID = 0;
const char AADereferenceable::ID = 0;
const char AAAlign::ID = 0;
const char AANoCapture::ID = 0;
const char AAValueSimplify::ID = 0;
const char AAHeapToStack::ID = 0;
const char AAMemoryBehavior::ID = 0;
const char AAValueConstantRange::ID = 0;
// Macro magic to create the static generator function for attributes that
// follow the naming scheme.
#define SWITCH_PK_INV(CLASS, PK, POS_NAME) \
case IRPosition::PK: \
llvm_unreachable("Cannot create " #CLASS " for a " POS_NAME " position!");
#define SWITCH_PK_CREATE(CLASS, IRP, PK, SUFFIX) \
case IRPosition::PK: \
AA = new CLASS##SUFFIX(IRP); \
break;
#define CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_FLOAT, "floating") \
SWITCH_PK_INV(CLASS, IRP_ARGUMENT, "argument") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_RETURNED, "call site returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_ARGUMENT, "call site argument") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
} \
return *AA; \
}
#define CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_FUNCTION, "function") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE, "call site") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_RETURNED, Returned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
#define CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_RETURNED, Returned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
#define CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_ARGUMENT, "argument") \
SWITCH_PK_INV(CLASS, IRP_FLOAT, "floating") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_RETURNED, "call site returned") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE_ARGUMENT, "call site argument") \
SWITCH_PK_INV(CLASS, IRP_CALL_SITE, "call site") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
} \
return *AA; \
}
#define CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION(CLASS) \
CLASS &CLASS::createForPosition(const IRPosition &IRP, Attributor &A) { \
CLASS *AA = nullptr; \
switch (IRP.getPositionKind()) { \
SWITCH_PK_INV(CLASS, IRP_INVALID, "invalid") \
SWITCH_PK_INV(CLASS, IRP_RETURNED, "returned") \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FUNCTION, Function) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE, CallSite) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_FLOAT, Floating) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_ARGUMENT, Argument) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_RETURNED, CallSiteReturned) \
SWITCH_PK_CREATE(CLASS, IRP, IRP_CALL_SITE_ARGUMENT, CallSiteArgument) \
} \
return *AA; \
}
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoUnwind)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoSync)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoRecurse)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAWillReturn)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoReturn)
CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAReturnedValues)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANonNull)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoAlias)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AADereferenceable)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAAlign)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoCapture)
CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAValueConstantRange)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAValueSimplify)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAIsDead)
CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION(AANoFree)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAHeapToStack)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAReachability)
CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAUndefinedBehavior)
CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION(AAMemoryBehavior)
#undef CREATE_FUNCTION_ONLY_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_FUNCTION_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_NON_RET_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_VALUE_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef CREATE_ALL_ABSTRACT_ATTRIBUTE_FOR_POSITION
#undef SWITCH_PK_CREATE
#undef SWITCH_PK_INV
INITIALIZE_PASS_BEGIN(AttributorLegacyPass, "attributor",
"Deduce and propagate attributes", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(AttributorLegacyPass, "attributor",
"Deduce and propagate attributes", false, false)