blob: 7c7a8eb04a2cc726f166f329b5f9b5f149f4b425 [file] [log] [blame]
//===- PredicateInfo.h - Build PredicateInfo ----------------------*-C++-*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// This file implements the PredicateInfo analysis, which creates an Extended
/// SSA form for operations used in branch comparisons and llvm.assume
/// comparisons.
/// Copies of these operations are inserted into the true/false edge (and after
/// assumes), and information attached to the copies. All uses of the original
/// operation in blocks dominated by the true/false edge (and assume), are
/// replaced with uses of the copies. This enables passes to easily and sparsely
/// propagate condition based info into the operations that may be affected.
/// Example:
/// %cmp = icmp eq i32 %x, 50
/// br i1 %cmp, label %true, label %false
/// true:
/// ret i32 %x
/// false:
/// ret i32 1
/// will become
/// %cmp = icmp eq i32, %x, 50
/// br i1 %cmp, label %true, label %false
/// true:
/// %x.0 = call \@llvm.ssa_copy.i32(i32 %x)
/// ret i32 %x.0
/// false:
/// ret i32 1
/// Using getPredicateInfoFor on x.0 will give you the comparison it is
/// dominated by (the icmp), and that you are located in the true edge of that
/// comparison, which tells you x.0 is 50.
/// In order to reduce the number of copies inserted, predicateinfo is only
/// inserted where it would actually be live. This means if there are no uses of
/// an operation dominated by the branch edges, or by an assume, the associated
/// predicate info is never inserted.
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/ilist.h"
#include "llvm/ADT/ilist_node.h"
#include "llvm/ADT/iterator.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/OrderedInstructions.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/OperandTraits.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include "llvm/PassAnalysisSupport.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <iterator>
#include <memory>
#include <utility>
namespace llvm {
class DominatorTree;
class Function;
class Instruction;
class MemoryAccess;
class LLVMContext;
class raw_ostream;
enum PredicateType { PT_Branch, PT_Assume, PT_Switch };
// Base class for all predicate information we provide.
// All of our predicate information has at least a comparison.
class PredicateBase : public ilist_node<PredicateBase> {
PredicateType Type;
// The original operand before we renamed it.
// This can be use by passes, when destroying predicateinfo, to know
// whether they can just drop the intrinsic, or have to merge metadata.
Value *OriginalOp;
PredicateBase(const PredicateBase &) = delete;
PredicateBase &operator=(const PredicateBase &) = delete;
PredicateBase() = delete;
virtual ~PredicateBase() = default;
PredicateBase(PredicateType PT, Value *Op) : Type(PT), OriginalOp(Op) {}
class PredicateWithCondition : public PredicateBase {
Value *Condition;
static bool classof(const PredicateBase *PB) {
return PB->Type == PT_Assume || PB->Type == PT_Branch ||
PB->Type == PT_Switch;
PredicateWithCondition(PredicateType PT, Value *Op, Value *Condition)
: PredicateBase(PT, Op), Condition(Condition) {}
// Provides predicate information for assumes. Since assumes are always true,
// we simply provide the assume instruction, so you can tell your relative
// position to it.
class PredicateAssume : public PredicateWithCondition {
IntrinsicInst *AssumeInst;
PredicateAssume(Value *Op, IntrinsicInst *AssumeInst, Value *Condition)
: PredicateWithCondition(PT_Assume, Op, Condition),
AssumeInst(AssumeInst) {}
PredicateAssume() = delete;
static bool classof(const PredicateBase *PB) {
return PB->Type == PT_Assume;
// Mixin class for edge predicates. The FROM block is the block where the
// predicate originates, and the TO block is the block where the predicate is
// valid.
class PredicateWithEdge : public PredicateWithCondition {
BasicBlock *From;
BasicBlock *To;
PredicateWithEdge() = delete;
static bool classof(const PredicateBase *PB) {
return PB->Type == PT_Branch || PB->Type == PT_Switch;
PredicateWithEdge(PredicateType PType, Value *Op, BasicBlock *From,
BasicBlock *To, Value *Cond)
: PredicateWithCondition(PType, Op, Cond), From(From), To(To) {}
// Provides predicate information for branches.
class PredicateBranch : public PredicateWithEdge {
// If true, SplitBB is the true successor, otherwise it's the false successor.
bool TrueEdge;
PredicateBranch(Value *Op, BasicBlock *BranchBB, BasicBlock *SplitBB,
Value *Condition, bool TakenEdge)
: PredicateWithEdge(PT_Branch, Op, BranchBB, SplitBB, Condition),
TrueEdge(TakenEdge) {}
PredicateBranch() = delete;
static bool classof(const PredicateBase *PB) {
return PB->Type == PT_Branch;
class PredicateSwitch : public PredicateWithEdge {
Value *CaseValue;
// This is the switch instruction.
SwitchInst *Switch;
PredicateSwitch(Value *Op, BasicBlock *SwitchBB, BasicBlock *TargetBB,
Value *CaseValue, SwitchInst *SI)
: PredicateWithEdge(PT_Switch, Op, SwitchBB, TargetBB,
CaseValue(CaseValue), Switch(SI) {}
PredicateSwitch() = delete;
static bool classof(const PredicateBase *PB) {
return PB->Type == PT_Switch;
// This name is used in a few places, so kick it into their own namespace
namespace PredicateInfoClasses {
struct ValueDFS;
/// Encapsulates PredicateInfo, including all data associated with memory
/// accesses.
class PredicateInfo {
// Used to store information about each value we might rename.
struct ValueInfo {
// Information about each possible copy. During processing, this is each
// inserted info. After processing, we move the uninserted ones to the
// uninserted vector.
SmallVector<PredicateBase *, 4> Infos;
SmallVector<PredicateBase *, 4> UninsertedInfos;
// This owns the all the predicate infos in the function, placed or not.
iplist<PredicateBase> AllInfos;
PredicateInfo(Function &, DominatorTree &, AssumptionCache &);
void verifyPredicateInfo() const;
void dump() const;
void print(raw_ostream &) const;
const PredicateBase *getPredicateInfoFor(const Value *V) const {
return PredicateMap.lookup(V);
// Used by PredicateInfo annotater, dumpers, and wrapper pass.
friend class PredicateInfoAnnotatedWriter;
friend class PredicateInfoPrinterLegacyPass;
void buildPredicateInfo();
void processAssume(IntrinsicInst *, BasicBlock *, SmallVectorImpl<Value *> &);
void processBranch(BranchInst *, BasicBlock *, SmallVectorImpl<Value *> &);
void processSwitch(SwitchInst *, BasicBlock *, SmallVectorImpl<Value *> &);
void renameUses(SmallVectorImpl<Value *> &);
using ValueDFS = PredicateInfoClasses::ValueDFS;
typedef SmallVectorImpl<ValueDFS> ValueDFSStack;
void convertUsesToDFSOrdered(Value *, SmallVectorImpl<ValueDFS> &);
Value *materializeStack(unsigned int &, ValueDFSStack &, Value *);
bool stackIsInScope(const ValueDFSStack &, const ValueDFS &) const;
void popStackUntilDFSScope(ValueDFSStack &, const ValueDFS &);
ValueInfo &getOrCreateValueInfo(Value *);
void addInfoFor(SmallVectorImpl<Value *> &OpsToRename, Value *Op,
PredicateBase *PB);
const ValueInfo &getValueInfo(Value *) const;
Function &F;
DominatorTree &DT;
AssumptionCache &AC;
OrderedInstructions OI;
// This maps from copy operands to Predicate Info. Note that it does not own
// the Predicate Info, they belong to the ValueInfo structs in the ValueInfos
// vector.
DenseMap<const Value *, const PredicateBase *> PredicateMap;
// This stores info about each operand or comparison result we make copies
// of. The real ValueInfos start at index 1, index 0 is unused so that we can
// more easily detect invalid indexing.
SmallVector<ValueInfo, 32> ValueInfos;
// This gives the index into the ValueInfos array for a given Value. Because
// 0 is not a valid Value Info index, you can use DenseMap::lookup and tell
// whether it returned a valid result.
DenseMap<Value *, unsigned int> ValueInfoNums;
// The set of edges along which we can only handle phi uses, due to critical
// edges.
DenseSet<std::pair<BasicBlock *, BasicBlock *>> EdgeUsesOnly;
// The set of ssa_copy declarations we created with our custom mangling.
SmallSet<AssertingVH<Function>, 20> CreatedDeclarations;
// This pass does eager building and then printing of PredicateInfo. It is used
// by
// the tests to be able to build, dump, and verify PredicateInfo.
class PredicateInfoPrinterLegacyPass : public FunctionPass {
static char ID;
bool runOnFunction(Function &) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
/// Printer pass for \c PredicateInfo.
class PredicateInfoPrinterPass
: public PassInfoMixin<PredicateInfoPrinterPass> {
raw_ostream &OS;
explicit PredicateInfoPrinterPass(raw_ostream &OS) : OS(OS) {}
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
/// Verifier pass for \c PredicateInfo.
struct PredicateInfoVerifierPass : PassInfoMixin<PredicateInfoVerifierPass> {
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
} // end namespace llvm