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swiftshader / SwiftShader / b73f419279dcf71d6fbf255a5d96ce53fff4c8f0 / . / third_party / llvm-16.0 / llvm / lib / CodeGen / AsmPrinter / AsmPrinter.cpp
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//===- AsmPrinter.cpp - Common AsmPrinter code ----------------------------===//
//
// 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 the AsmPrinter class.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/AsmPrinter.h"
#include "CodeViewDebug.h"
#include "DwarfDebug.h"
#include "DwarfException.h"
#include "PseudoProbePrinter.h"
#include "WasmException.h"
#include "WinCFGuard.h"
#include "WinException.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/EHPersonalities.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBundle.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/Config/config.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Comdat.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GCStrategy.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalIFunc.h"
#include "llvm/IR/GlobalObject.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PseudoProbe.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDirectives.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolELF.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/Pass.h"
#include "llvm/Remarks/RemarkStreamer.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include <algorithm>
#include <cassert>
#include <cinttypes>
#include <cstdint>
#include <iterator>
#include <memory>
#include <optional>
#include <string>
#include <utility>
#include <vector>
using namespace llvm;
#define DEBUG_TYPE "asm-printer"
const char DWARFGroupName[] = "dwarf";
const char DWARFGroupDescription[] = "DWARF Emission";
const char DbgTimerName[] = "emit";
const char DbgTimerDescription[] = "Debug Info Emission";
const char EHTimerName[] = "write_exception";
const char EHTimerDescription[] = "DWARF Exception Writer";
const char CFGuardName[] = "Control Flow Guard";
const char CFGuardDescription[] = "Control Flow Guard";
const char CodeViewLineTablesGroupName[] = "linetables";
const char CodeViewLineTablesGroupDescription[] = "CodeView Line Tables";
const char PPTimerName[] = "emit";
const char PPTimerDescription[] = "Pseudo Probe Emission";
const char PPGroupName[] = "pseudo probe";
const char PPGroupDescription[] = "Pseudo Probe Emission";
STATISTIC(EmittedInsts, "Number of machine instrs printed");
char AsmPrinter::ID = 0;
namespace {
class AddrLabelMapCallbackPtr final : CallbackVH {
AddrLabelMap *Map = nullptr;
public:
AddrLabelMapCallbackPtr() = default;
AddrLabelMapCallbackPtr(Value *V) : CallbackVH(V) {}
void setPtr(BasicBlock *BB) {
ValueHandleBase::operator=(BB);
}
void setMap(AddrLabelMap *map) { Map = map; }
void deleted() override;
void allUsesReplacedWith(Value *V2) override;
};
} // namespace
class llvm::AddrLabelMap {
MCContext &Context;
struct AddrLabelSymEntry {
/// The symbols for the label.
TinyPtrVector<MCSymbol *> Symbols;
Function *Fn; // The containing function of the BasicBlock.
unsigned Index; // The index in BBCallbacks for the BasicBlock.
};
DenseMap<AssertingVH<BasicBlock>, AddrLabelSymEntry> AddrLabelSymbols;
/// Callbacks for the BasicBlock's that we have entries for. We use this so
/// we get notified if a block is deleted or RAUWd.
std::vector<AddrLabelMapCallbackPtr> BBCallbacks;
/// This is a per-function list of symbols whose corresponding BasicBlock got
/// deleted. These symbols need to be emitted at some point in the file, so
/// AsmPrinter emits them after the function body.
DenseMap<AssertingVH<Function>, std::vector<MCSymbol *>>
DeletedAddrLabelsNeedingEmission;
public:
AddrLabelMap(MCContext &context) : Context(context) {}
~AddrLabelMap() {
assert(DeletedAddrLabelsNeedingEmission.empty() &&
"Some labels for deleted blocks never got emitted");
}
ArrayRef<MCSymbol *> getAddrLabelSymbolToEmit(BasicBlock *BB);
void takeDeletedSymbolsForFunction(Function *F,
std::vector<MCSymbol *> &Result);
void UpdateForDeletedBlock(BasicBlock *BB);
void UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New);
};
ArrayRef<MCSymbol *> AddrLabelMap::getAddrLabelSymbolToEmit(BasicBlock *BB) {
assert(BB->hasAddressTaken() &&
"Shouldn't get label for block without address taken");
AddrLabelSymEntry &Entry = AddrLabelSymbols[BB];
// If we already had an entry for this block, just return it.
if (!Entry.Symbols.empty()) {
assert(BB->getParent() == Entry.Fn && "Parent changed");
return Entry.Symbols;
}
// Otherwise, this is a new entry, create a new symbol for it and add an
// entry to BBCallbacks so we can be notified if the BB is deleted or RAUWd.
BBCallbacks.emplace_back(BB);
BBCallbacks.back().setMap(this);
Entry.Index = BBCallbacks.size() - 1;
Entry.Fn = BB->getParent();
MCSymbol *Sym = BB->hasAddressTaken() ? Context.createNamedTempSymbol()
: Context.createTempSymbol();
Entry.Symbols.push_back(Sym);
return Entry.Symbols;
}
/// If we have any deleted symbols for F, return them.
void AddrLabelMap::takeDeletedSymbolsForFunction(
Function *F, std::vector<MCSymbol *> &Result) {
DenseMap<AssertingVH<Function>, std::vector<MCSymbol *>>::iterator I =
DeletedAddrLabelsNeedingEmission.find(F);
// If there are no entries for the function, just return.
if (I == DeletedAddrLabelsNeedingEmission.end())
return;
// Otherwise, take the list.
std::swap(Result, I->second);
DeletedAddrLabelsNeedingEmission.erase(I);
}
//===- Address of Block Management ----------------------------------------===//
ArrayRef<MCSymbol *>
AsmPrinter::getAddrLabelSymbolToEmit(const BasicBlock *BB) {
// Lazily create AddrLabelSymbols.
if (!AddrLabelSymbols)
AddrLabelSymbols = std::make_unique<AddrLabelMap>(OutContext);
return AddrLabelSymbols->getAddrLabelSymbolToEmit(
const_cast<BasicBlock *>(BB));
}
void AsmPrinter::takeDeletedSymbolsForFunction(
const Function *F, std::vector<MCSymbol *> &Result) {
// If no blocks have had their addresses taken, we're done.
if (!AddrLabelSymbols)
return;
return AddrLabelSymbols->takeDeletedSymbolsForFunction(
const_cast<Function *>(F), Result);
}
void AddrLabelMap::UpdateForDeletedBlock(BasicBlock *BB) {
// If the block got deleted, there is no need for the symbol. If the symbol
// was already emitted, we can just forget about it, otherwise we need to
// queue it up for later emission when the function is output.
AddrLabelSymEntry Entry = std::move(AddrLabelSymbols[BB]);
AddrLabelSymbols.erase(BB);
assert(!Entry.Symbols.empty() && "Didn't have a symbol, why a callback?");
BBCallbacks[Entry.Index] = nullptr; // Clear the callback.
#if !LLVM_MEMORY_SANITIZER_BUILD
// BasicBlock is destroyed already, so this access is UB detectable by msan.
assert((BB->getParent() == nullptr || BB->getParent() == Entry.Fn) &&
"Block/parent mismatch");
#endif
for (MCSymbol *Sym : Entry.Symbols) {
if (Sym->isDefined())
return;
// If the block is not yet defined, we need to emit it at the end of the
// function. Add the symbol to the DeletedAddrLabelsNeedingEmission list
// for the containing Function. Since the block is being deleted, its
// parent may already be removed, we have to get the function from 'Entry'.
DeletedAddrLabelsNeedingEmission[Entry.Fn].push_back(Sym);
}
}
void AddrLabelMap::UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New) {
// Get the entry for the RAUW'd block and remove it from our map.
AddrLabelSymEntry OldEntry = std::move(AddrLabelSymbols[Old]);
AddrLabelSymbols.erase(Old);
assert(!OldEntry.Symbols.empty() && "Didn't have a symbol, why a callback?");
AddrLabelSymEntry &NewEntry = AddrLabelSymbols[New];
// If New is not address taken, just move our symbol over to it.
if (NewEntry.Symbols.empty()) {
BBCallbacks[OldEntry.Index].setPtr(New); // Update the callback.
NewEntry = std::move(OldEntry); // Set New's entry.
return;
}
BBCallbacks[OldEntry.Index] = nullptr; // Update the callback.
// Otherwise, we need to add the old symbols to the new block's set.
llvm::append_range(NewEntry.Symbols, OldEntry.Symbols);
}
void AddrLabelMapCallbackPtr::deleted() {
Map->UpdateForDeletedBlock(cast<BasicBlock>(getValPtr()));
}
void AddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) {
Map->UpdateForRAUWBlock(cast<BasicBlock>(getValPtr()), cast<BasicBlock>(V2));
}
/// getGVAlignment - Return the alignment to use for the specified global
/// value. This rounds up to the preferred alignment if possible and legal.
Align AsmPrinter::getGVAlignment(const GlobalObject *GV, const DataLayout &DL,
Align InAlign) {
Align Alignment;
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
Alignment = DL.getPreferredAlign(GVar);
// If InAlign is specified, round it to it.
if (InAlign > Alignment)
Alignment = InAlign;
// If the GV has a specified alignment, take it into account.
const MaybeAlign GVAlign(GV->getAlign());
if (!GVAlign)
return Alignment;
assert(GVAlign && "GVAlign must be set");
// If the GVAlign is larger than NumBits, or if we are required to obey
// NumBits because the GV has an assigned section, obey it.
if (*GVAlign > Alignment || GV->hasSection())
Alignment = *GVAlign;
return Alignment;
}
AsmPrinter::AsmPrinter(TargetMachine &tm, std::unique_ptr<MCStreamer> Streamer)
: MachineFunctionPass(ID), TM(tm), MAI(tm.getMCAsmInfo()),
OutContext(Streamer->getContext()), OutStreamer(std::move(Streamer)),
SM(*this) {
VerboseAsm = OutStreamer->isVerboseAsm();
DwarfUsesRelocationsAcrossSections =
MAI->doesDwarfUseRelocationsAcrossSections();
}
AsmPrinter::~AsmPrinter() {
assert(!DD && Handlers.size() == NumUserHandlers &&
"Debug/EH info didn't get finalized");
}
bool AsmPrinter::isPositionIndependent() const {
return TM.isPositionIndependent();
}
/// getFunctionNumber - Return a unique ID for the current function.
unsigned AsmPrinter::getFunctionNumber() const {
return MF->getFunctionNumber();
}
const TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
return *TM.getObjFileLowering();
}
const DataLayout &AsmPrinter::getDataLayout() const {
return MMI->getModule()->getDataLayout();
}
// Do not use the cached DataLayout because some client use it without a Module
// (dsymutil, llvm-dwarfdump).
unsigned AsmPrinter::getPointerSize() const {
return TM.getPointerSize(0); // FIXME: Default address space
}
const MCSubtargetInfo &AsmPrinter::getSubtargetInfo() const {
assert(MF && "getSubtargetInfo requires a valid MachineFunction!");
return MF->getSubtarget<MCSubtargetInfo>();
}
void AsmPrinter::EmitToStreamer(MCStreamer &S, const MCInst &Inst) {
S.emitInstruction(Inst, getSubtargetInfo());
}
void AsmPrinter::emitInitialRawDwarfLocDirective(const MachineFunction &MF) {
if (DD) {
assert(OutStreamer->hasRawTextSupport() &&
"Expected assembly output mode.");
// This is NVPTX specific and it's unclear why.
// PR51079: If we have code without debug information we need to give up.
DISubprogram *MFSP = MF.getFunction().getSubprogram();
if (!MFSP)
return;
(void)DD->emitInitialLocDirective(MF, /*CUID=*/0);
}
}
/// getCurrentSection() - Return the current section we are emitting to.
const MCSection *AsmPrinter::getCurrentSection() const {
return OutStreamer->getCurrentSectionOnly();
}
void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
AU.addRequired<MachineOptimizationRemarkEmitterPass>();
AU.addRequired<GCModuleInfo>();
}
bool AsmPrinter::doInitialization(Module &M) {
auto *MMIWP = getAnalysisIfAvailable<MachineModuleInfoWrapperPass>();
MMI = MMIWP ? &MMIWP->getMMI() : nullptr;
HasSplitStack = false;
HasNoSplitStack = false;
AddrLabelSymbols = nullptr;
// Initialize TargetLoweringObjectFile.
const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
.Initialize(OutContext, TM);
const_cast<TargetLoweringObjectFile &>(getObjFileLowering())
.getModuleMetadata(M);
OutStreamer->initSections(false, *TM.getMCSubtargetInfo());
// Emit the version-min deployment target directive if needed.
//
// FIXME: If we end up with a collection of these sorts of Darwin-specific
// or ELF-specific things, it may make sense to have a platform helper class
// that will work with the target helper class. For now keep it here, as the
// alternative is duplicated code in each of the target asm printers that
// use the directive, where it would need the same conditionalization
// anyway.
const Triple &Target = TM.getTargetTriple();
Triple TVT(M.getDarwinTargetVariantTriple());
OutStreamer->emitVersionForTarget(
Target, M.getSDKVersion(),
M.getDarwinTargetVariantTriple().empty() ? nullptr : &TVT,
M.getDarwinTargetVariantSDKVersion());
// Allow the target to emit any magic that it wants at the start of the file.
emitStartOfAsmFile(M);
// Very minimal debug info. It is ignored if we emit actual debug info. If we
// don't, this at least helps the user find where a global came from.
if (MAI->hasSingleParameterDotFile()) {
// .file "foo.c"
SmallString<128> FileName;
if (MAI->hasBasenameOnlyForFileDirective())
FileName = llvm::sys::path::filename(M.getSourceFileName());
else
FileName = M.getSourceFileName();
if (MAI->hasFourStringsDotFile()) {
#ifdef PACKAGE_VENDOR
const char VerStr[] =
PACKAGE_VENDOR " " PACKAGE_NAME " version " PACKAGE_VERSION;
#else
const char VerStr[] = PACKAGE_NAME " version " PACKAGE_VERSION;
#endif
// TODO: Add timestamp and description.
OutStreamer->emitFileDirective(FileName, VerStr, "", "");
} else {
OutStreamer->emitFileDirective(FileName);
}
}
GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
assert(MI && "AsmPrinter didn't require GCModuleInfo?");
for (const auto &I : *MI)
if (GCMetadataPrinter *MP = getOrCreateGCPrinter(*I))
MP->beginAssembly(M, *MI, *this);
// Emit module-level inline asm if it exists.
if (!M.getModuleInlineAsm().empty()) {
OutStreamer->AddComment("Start of file scope inline assembly");
OutStreamer->addBlankLine();
emitInlineAsm(M.getModuleInlineAsm() + "\n", *TM.getMCSubtargetInfo(),
TM.Options.MCOptions);
OutStreamer->AddComment("End of file scope inline assembly");
OutStreamer->addBlankLine();
}
if (MAI->doesSupportDebugInformation()) {
bool EmitCodeView = M.getCodeViewFlag();
if (EmitCodeView && TM.getTargetTriple().isOSWindows()) {
Handlers.emplace_back(std::make_unique<CodeViewDebug>(this),
DbgTimerName, DbgTimerDescription,
CodeViewLineTablesGroupName,
CodeViewLineTablesGroupDescription);
}
if (!EmitCodeView || M.getDwarfVersion()) {
if (MMI->hasDebugInfo()) {
DD = new DwarfDebug(this);
Handlers.emplace_back(std::unique_ptr<DwarfDebug>(DD), DbgTimerName,
DbgTimerDescription, DWARFGroupName,
DWARFGroupDescription);
}
}
}
if (M.getNamedMetadata(PseudoProbeDescMetadataName)) {
PP = new PseudoProbeHandler(this);
Handlers.emplace_back(std::unique_ptr<PseudoProbeHandler>(PP), PPTimerName,
PPTimerDescription, PPGroupName, PPGroupDescription);
}
switch (MAI->getExceptionHandlingType()) {
case ExceptionHandling::None:
// We may want to emit CFI for debug.
[[fallthrough]];
case ExceptionHandling::SjLj:
case ExceptionHandling::DwarfCFI:
case ExceptionHandling::ARM:
for (auto &F : M.getFunctionList()) {
if (getFunctionCFISectionType(F) != CFISection::None)
ModuleCFISection = getFunctionCFISectionType(F);
// If any function needsUnwindTableEntry(), it needs .eh_frame and hence
// the module needs .eh_frame. If we have found that case, we are done.
if (ModuleCFISection == CFISection::EH)
break;
}
assert(MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI ||
ModuleCFISection != CFISection::EH);
break;
default:
break;
}
EHStreamer *ES = nullptr;
switch (MAI->getExceptionHandlingType()) {
case ExceptionHandling::None:
if (!needsCFIForDebug())
break;
[[fallthrough]];
case ExceptionHandling::SjLj:
case ExceptionHandling::DwarfCFI:
ES = new DwarfCFIException(this);
break;
case ExceptionHandling::ARM:
ES = new ARMException(this);
break;
case ExceptionHandling::WinEH:
switch (MAI->getWinEHEncodingType()) {
default: llvm_unreachable("unsupported unwinding information encoding");
case WinEH::EncodingType::Invalid:
break;
case WinEH::EncodingType::X86:
case WinEH::EncodingType::Itanium:
ES = new WinException(this);
break;
}
break;
case ExceptionHandling::Wasm:
ES = new WasmException(this);
break;
case ExceptionHandling::AIX:
ES = new AIXException(this);
break;
}
if (ES)
Handlers.emplace_back(std::unique_ptr<EHStreamer>(ES), EHTimerName,
EHTimerDescription, DWARFGroupName,
DWARFGroupDescription);
// Emit tables for any value of cfguard flag (i.e. cfguard=1 or cfguard=2).
if (mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("cfguard")))
Handlers.emplace_back(std::make_unique<WinCFGuard>(this), CFGuardName,
CFGuardDescription, DWARFGroupName,
DWARFGroupDescription);
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->beginModule(&M);
}
return false;
}
static bool canBeHidden(const GlobalValue *GV, const MCAsmInfo &MAI) {
if (!MAI.hasWeakDefCanBeHiddenDirective())
return false;
return GV->canBeOmittedFromSymbolTable();
}
void AsmPrinter::emitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
GlobalValue::LinkageTypes Linkage = GV->getLinkage();
switch (Linkage) {
case GlobalValue::CommonLinkage:
case GlobalValue::LinkOnceAnyLinkage:
case GlobalValue::LinkOnceODRLinkage:
case GlobalValue::WeakAnyLinkage:
case GlobalValue::WeakODRLinkage:
if (MAI->hasWeakDefDirective()) {
// .globl _foo
OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
if (!canBeHidden(GV, *MAI))
// .weak_definition _foo
OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefinition);
else
OutStreamer->emitSymbolAttribute(GVSym, MCSA_WeakDefAutoPrivate);
} else if (MAI->avoidWeakIfComdat() && GV->hasComdat()) {
// .globl _foo
OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
//NOTE: linkonce is handled by the section the symbol was assigned to.
} else {
// .weak _foo
OutStreamer->emitSymbolAttribute(GVSym, MCSA_Weak);
}
return;
case GlobalValue::ExternalLinkage:
OutStreamer->emitSymbolAttribute(GVSym, MCSA_Global);
return;
case GlobalValue::PrivateLinkage:
case GlobalValue::InternalLinkage:
return;
case GlobalValue::ExternalWeakLinkage:
case GlobalValue::AvailableExternallyLinkage:
case GlobalValue::AppendingLinkage:
llvm_unreachable("Should never emit this");
}
llvm_unreachable("Unknown linkage type!");
}
void AsmPrinter::getNameWithPrefix(SmallVectorImpl<char> &Name,
const GlobalValue *GV) const {
TM.getNameWithPrefix(Name, GV, getObjFileLowering().getMangler());
}
MCSymbol *AsmPrinter::getSymbol(const GlobalValue *GV) const {
return TM.getSymbol(GV);
}
MCSymbol *AsmPrinter::getSymbolPreferLocal(const GlobalValue &GV) const {
// On ELF, use .Lfoo$local if GV is a non-interposable GlobalObject with an
// exact definion (intersection of GlobalValue::hasExactDefinition() and
// !isInterposable()). These linkages include: external, appending, internal,
// private. It may be profitable to use a local alias for external. The
// assembler would otherwise be conservative and assume a global default
// visibility symbol can be interposable, even if the code generator already
// assumed it.
if (TM.getTargetTriple().isOSBinFormatELF() && GV.canBenefitFromLocalAlias()) {
const Module &M = *GV.getParent();
if (TM.getRelocationModel() != Reloc::Static &&
M.getPIELevel() == PIELevel::Default && GV.isDSOLocal())
return getSymbolWithGlobalValueBase(&GV, "$local");
}
return TM.getSymbol(&GV);
}
/// EmitGlobalVariable - Emit the specified global variable to the .s file.
void AsmPrinter::emitGlobalVariable(const GlobalVariable *GV) {
bool IsEmuTLSVar = TM.useEmulatedTLS() && GV->isThreadLocal();
assert(!(IsEmuTLSVar && GV->hasCommonLinkage()) &&
"No emulated TLS variables in the common section");
// Never emit TLS variable xyz in emulated TLS model.
// The initialization value is in __emutls_t.xyz instead of xyz.
if (IsEmuTLSVar)
return;
if (GV->hasInitializer()) {
// Check to see if this is a special global used by LLVM, if so, emit it.
if (emitSpecialLLVMGlobal(GV))
return;
// Skip the emission of global equivalents. The symbol can be emitted later
// on by emitGlobalGOTEquivs in case it turns out to be needed.
if (GlobalGOTEquivs.count(getSymbol(GV)))
return;
if (isVerbose()) {
// When printing the control variable __emutls_v.*,
// we don't need to print the original TLS variable name.
GV->printAsOperand(OutStreamer->getCommentOS(),
/*PrintType=*/false, GV->getParent());
OutStreamer->getCommentOS() << '\n';
}
}
MCSymbol *GVSym = getSymbol(GV);
MCSymbol *EmittedSym = GVSym;
// getOrCreateEmuTLSControlSym only creates the symbol with name and default
// attributes.
// GV's or GVSym's attributes will be used for the EmittedSym.
emitVisibility(EmittedSym, GV->getVisibility(), !GV->isDeclaration());
if (GV->isTagged()) {
Triple T = TM.getTargetTriple();
if (T.getArch() != Triple::aarch64 || !T.isAndroid())
OutContext.reportError(SMLoc(),
"Tagged symbols (-fsanitize=memtag-globals) are "
"only supported on aarch64 + Android.");
OutStreamer->emitSymbolAttribute(EmittedSym, MAI->getMemtagAttr());
}
if (!GV->hasInitializer()) // External globals require no extra code.
return;
GVSym->redefineIfPossible();
if (GVSym->isDefined() || GVSym->isVariable())
OutContext.reportError(SMLoc(), "symbol '" + Twine(GVSym->getName()) +
"' is already defined");
if (MAI->hasDotTypeDotSizeDirective())
OutStreamer->emitSymbolAttribute(EmittedSym, MCSA_ELF_TypeObject);
SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
const DataLayout &DL = GV->getParent()->getDataLayout();
uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
// If the alignment is specified, we *must* obey it. Overaligning a global
// with a specified alignment is a prompt way to break globals emitted to
// sections and expected to be contiguous (e.g. ObjC metadata).
const Align Alignment = getGVAlignment(GV, DL);
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription,
HI.TimerGroupName, HI.TimerGroupDescription,
TimePassesIsEnabled);
HI.Handler->setSymbolSize(GVSym, Size);
}
// Handle common symbols
if (GVKind.isCommon()) {
if (Size == 0) Size = 1; // .comm Foo, 0 is undefined, avoid it.
// .comm _foo, 42, 4
OutStreamer->emitCommonSymbol(GVSym, Size, Alignment);
return;
}
// Determine to which section this global should be emitted.
MCSection *TheSection = getObjFileLowering().SectionForGlobal(GV, GVKind, TM);
// If we have a bss global going to a section that supports the
// zerofill directive, do so here.
if (GVKind.isBSS() && MAI->hasMachoZeroFillDirective() &&
TheSection->isVirtualSection()) {
if (Size == 0)
Size = 1; // zerofill of 0 bytes is undefined.
emitLinkage(GV, GVSym);
// .zerofill __DATA, __bss, _foo, 400, 5
OutStreamer->emitZerofill(TheSection, GVSym, Size, Alignment);
return;
}
// If this is a BSS local symbol and we are emitting in the BSS
// section use .lcomm/.comm directive.
if (GVKind.isBSSLocal() &&
getObjFileLowering().getBSSSection() == TheSection) {
if (Size == 0)
Size = 1; // .comm Foo, 0 is undefined, avoid it.
// Use .lcomm only if it supports user-specified alignment.
// Otherwise, while it would still be correct to use .lcomm in some
// cases (e.g. when Align == 1), the external assembler might enfore
// some -unknown- default alignment behavior, which could cause
// spurious differences between external and integrated assembler.
// Prefer to simply fall back to .local / .comm in this case.
if (MAI->getLCOMMDirectiveAlignmentType() != LCOMM::NoAlignment) {
// .lcomm _foo, 42
OutStreamer->emitLocalCommonSymbol(GVSym, Size, Alignment);
return;
}
// .local _foo
OutStreamer->emitSymbolAttribute(GVSym, MCSA_Local);
// .comm _foo, 42, 4
OutStreamer->emitCommonSymbol(GVSym, Size, Alignment);
return;
}
// Handle thread local data for mach-o which requires us to output an
// additional structure of data and mangle the original symbol so that we
// can reference it later.
//
// TODO: This should become an "emit thread local global" method on TLOF.
// All of this macho specific stuff should be sunk down into TLOFMachO and
// stuff like "TLSExtraDataSection" should no longer be part of the parent
// TLOF class. This will also make it more obvious that stuff like
// MCStreamer::EmitTBSSSymbol is macho specific and only called from macho
// specific code.
if (GVKind.isThreadLocal() && MAI->hasMachoTBSSDirective()) {
// Emit the .tbss symbol
MCSymbol *MangSym =
OutContext.getOrCreateSymbol(GVSym->getName() + Twine("$tlv$init"));
if (GVKind.isThreadBSS()) {
TheSection = getObjFileLowering().getTLSBSSSection();
OutStreamer->emitTBSSSymbol(TheSection, MangSym, Size, Alignment);
} else if (GVKind.isThreadData()) {
OutStreamer->switchSection(TheSection);
emitAlignment(Alignment, GV);
OutStreamer->emitLabel(MangSym);
emitGlobalConstant(GV->getParent()->getDataLayout(),
GV->getInitializer());
}
OutStreamer->addBlankLine();
// Emit the variable struct for the runtime.
MCSection *TLVSect = getObjFileLowering().getTLSExtraDataSection();
OutStreamer->switchSection(TLVSect);
// Emit the linkage here.
emitLinkage(GV, GVSym);
OutStreamer->emitLabel(GVSym);
// Three pointers in size:
// - __tlv_bootstrap - used to make sure support exists
// - spare pointer, used when mapped by the runtime
// - pointer to mangled symbol above with initializer
unsigned PtrSize = DL.getPointerTypeSize(GV->getType());
OutStreamer->emitSymbolValue(GetExternalSymbolSymbol("_tlv_bootstrap"),
PtrSize);
OutStreamer->emitIntValue(0, PtrSize);
OutStreamer->emitSymbolValue(MangSym, PtrSize);
OutStreamer->addBlankLine();
return;
}
MCSymbol *EmittedInitSym = GVSym;
OutStreamer->switchSection(TheSection);
emitLinkage(GV, EmittedInitSym);
emitAlignment(Alignment, GV);
OutStreamer->emitLabel(EmittedInitSym);
MCSymbol *LocalAlias = getSymbolPreferLocal(*GV);
if (LocalAlias != EmittedInitSym)
OutStreamer->emitLabel(LocalAlias);
emitGlobalConstant(GV->getParent()->getDataLayout(), GV->getInitializer());
if (MAI->hasDotTypeDotSizeDirective())
// .size foo, 42
OutStreamer->emitELFSize(EmittedInitSym,
MCConstantExpr::create(Size, OutContext));
OutStreamer->addBlankLine();
}
/// Emit the directive and value for debug thread local expression
///
/// \p Value - The value to emit.
/// \p Size - The size of the integer (in bytes) to emit.
void AsmPrinter::emitDebugValue(const MCExpr *Value, unsigned Size) const {
OutStreamer->emitValue(Value, Size);
}
void AsmPrinter::emitFunctionHeaderComment() {}
/// EmitFunctionHeader - This method emits the header for the current
/// function.
void AsmPrinter::emitFunctionHeader() {
const Function &F = MF->getFunction();
if (isVerbose())
OutStreamer->getCommentOS()
<< "-- Begin function "
<< GlobalValue::dropLLVMManglingEscape(F.getName()) << '\n';
// Print out constants referenced by the function
emitConstantPool();
// Print the 'header' of function.
// If basic block sections are desired, explicitly request a unique section
// for this function's entry block.
if (MF->front().isBeginSection())
MF->setSection(getObjFileLowering().getUniqueSectionForFunction(F, TM));
else
MF->setSection(getObjFileLowering().SectionForGlobal(&F, TM));
OutStreamer->switchSection(MF->getSection());
if (!MAI->hasVisibilityOnlyWithLinkage())
emitVisibility(CurrentFnSym, F.getVisibility());
if (MAI->needsFunctionDescriptors())
emitLinkage(&F, CurrentFnDescSym);
emitLinkage(&F, CurrentFnSym);
if (MAI->hasFunctionAlignment())
emitAlignment(MF->getAlignment(), &F);
if (MAI->hasDotTypeDotSizeDirective())
OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_ELF_TypeFunction);
if (F.hasFnAttribute(Attribute::Cold))
OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_Cold);
if (isVerbose()) {
F.printAsOperand(OutStreamer->getCommentOS(),
/*PrintType=*/false, F.getParent());
emitFunctionHeaderComment();
OutStreamer->getCommentOS() << '\n';
}
// Emit the prefix data.
if (F.hasPrefixData()) {
if (MAI->hasSubsectionsViaSymbols()) {
// Preserving prefix data on platforms which use subsections-via-symbols
// is a bit tricky. Here we introduce a symbol for the prefix data
// and use the .alt_entry attribute to mark the function's real entry point
// as an alternative entry point to the prefix-data symbol.
MCSymbol *PrefixSym = OutContext.createLinkerPrivateTempSymbol();
OutStreamer->emitLabel(PrefixSym);
emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
// Emit an .alt_entry directive for the actual function symbol.
OutStreamer->emitSymbolAttribute(CurrentFnSym, MCSA_AltEntry);
} else {
emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrefixData());
}
}
// Emit KCFI type information before patchable-function-prefix nops.
emitKCFITypeId(*MF);
// Emit M NOPs for -fpatchable-function-entry=N,M where M>0. We arbitrarily
// place prefix data before NOPs.
unsigned PatchableFunctionPrefix = 0;
unsigned PatchableFunctionEntry = 0;
(void)F.getFnAttribute("patchable-function-prefix")
.getValueAsString()
.getAsInteger(10, PatchableFunctionPrefix);
(void)F.getFnAttribute("patchable-function-entry")
.getValueAsString()
.getAsInteger(10, PatchableFunctionEntry);
if (PatchableFunctionPrefix) {
CurrentPatchableFunctionEntrySym =
OutContext.createLinkerPrivateTempSymbol();
OutStreamer->emitLabel(CurrentPatchableFunctionEntrySym);
emitNops(PatchableFunctionPrefix);
} else if (PatchableFunctionEntry) {
// May be reassigned when emitting the body, to reference the label after
// the initial BTI (AArch64) or endbr32/endbr64 (x86).
CurrentPatchableFunctionEntrySym = CurrentFnBegin;
}
// Emit the function descriptor. This is a virtual function to allow targets
// to emit their specific function descriptor. Right now it is only used by
// the AIX target. The PowerPC 64-bit V1 ELF target also uses function
// descriptors and should be converted to use this hook as well.
if (MAI->needsFunctionDescriptors())
emitFunctionDescriptor();
// Emit the CurrentFnSym. This is a virtual function to allow targets to do
// their wild and crazy things as required.
emitFunctionEntryLabel();
// If the function had address-taken blocks that got deleted, then we have
// references to the dangling symbols. Emit them at the start of the function
// so that we don't get references to undefined symbols.
std::vector<MCSymbol*> DeadBlockSyms;
takeDeletedSymbolsForFunction(&F, DeadBlockSyms);
for (MCSymbol *DeadBlockSym : DeadBlockSyms) {
OutStreamer->AddComment("Address taken block that was later removed");
OutStreamer->emitLabel(DeadBlockSym);
}
if (CurrentFnBegin) {
if (MAI->useAssignmentForEHBegin()) {
MCSymbol *CurPos = OutContext.createTempSymbol();
OutStreamer->emitLabel(CurPos);
OutStreamer->emitAssignment(CurrentFnBegin,
MCSymbolRefExpr::create(CurPos, OutContext));
} else {
OutStreamer->emitLabel(CurrentFnBegin);
}
}
// Emit pre-function debug and/or EH information.
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->beginFunction(MF);
}
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->beginBasicBlockSection(MF->front());
}
// Emit the prologue data.
if (F.hasPrologueData())
emitGlobalConstant(F.getParent()->getDataLayout(), F.getPrologueData());
// Emit the function prologue data for the indirect call sanitizer.
if (const MDNode *MD = F.getMetadata(LLVMContext::MD_func_sanitize)) {
assert(TM.getTargetTriple().getArch() == Triple::x86 ||
TM.getTargetTriple().getArch() == Triple::x86_64);
assert(MD->getNumOperands() == 2);
auto *PrologueSig = mdconst::extract<Constant>(MD->getOperand(0));
auto *FTRTTIProxy = mdconst::extract<Constant>(MD->getOperand(1));
assert(PrologueSig && FTRTTIProxy);
emitGlobalConstant(F.getParent()->getDataLayout(), PrologueSig);
const MCExpr *Proxy = lowerConstant(FTRTTIProxy);
const MCExpr *FnExp = MCSymbolRefExpr::create(CurrentFnSym, OutContext);
const MCExpr *PCRel = MCBinaryExpr::createSub(Proxy, FnExp, OutContext);
// Use 32 bit since only small code model is supported.
OutStreamer->emitValue(PCRel, 4u);
}
}
/// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the
/// function. This can be overridden by targets as required to do custom stuff.
void AsmPrinter::emitFunctionEntryLabel() {
CurrentFnSym->redefineIfPossible();
// The function label could have already been emitted if two symbols end up
// conflicting due to asm renaming. Detect this and emit an error.
if (CurrentFnSym->isVariable())
report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
"' is a protected alias");
OutStreamer->emitLabel(CurrentFnSym);
if (TM.getTargetTriple().isOSBinFormatELF()) {
MCSymbol *Sym = getSymbolPreferLocal(MF->getFunction());
if (Sym != CurrentFnSym) {
cast<MCSymbolELF>(Sym)->setType(ELF::STT_FUNC);
CurrentFnBeginLocal = Sym;
OutStreamer->emitLabel(Sym);
if (MAI->hasDotTypeDotSizeDirective())
OutStreamer->emitSymbolAttribute(Sym, MCSA_ELF_TypeFunction);
}
}
}
/// emitComments - Pretty-print comments for instructions.
static void emitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
const MachineFunction *MF = MI.getMF();
const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
// Check for spills and reloads
// We assume a single instruction only has a spill or reload, not
// both.
std::optional<unsigned> Size;
if ((Size = MI.getRestoreSize(TII))) {
CommentOS << *Size << "-byte Reload\n";
} else if ((Size = MI.getFoldedRestoreSize(TII))) {
if (*Size) {
if (*Size == unsigned(MemoryLocation::UnknownSize))
CommentOS << "Unknown-size Folded Reload\n";
else
CommentOS << *Size << "-byte Folded Reload\n";
}
} else if ((Size = MI.getSpillSize(TII))) {
CommentOS << *Size << "-byte Spill\n";
} else if ((Size = MI.getFoldedSpillSize(TII))) {
if (*Size) {
if (*Size == unsigned(MemoryLocation::UnknownSize))
CommentOS << "Unknown-size Folded Spill\n";
else
CommentOS << *Size << "-byte Folded Spill\n";
}
}
// Check for spill-induced copies
if (MI.getAsmPrinterFlag(MachineInstr::ReloadReuse))
CommentOS << " Reload Reuse\n";
}
/// emitImplicitDef - This method emits the specified machine instruction
/// that is an implicit def.
void AsmPrinter::emitImplicitDef(const MachineInstr *MI) const {
Register RegNo = MI->getOperand(0).getReg();
SmallString<128> Str;
raw_svector_ostream OS(Str);
OS << "implicit-def: "
<< printReg(RegNo, MF->getSubtarget().getRegisterInfo());
OutStreamer->AddComment(OS.str());
OutStreamer->addBlankLine();
}
static void emitKill(const MachineInstr *MI, AsmPrinter &AP) {
std::string Str;
raw_string_ostream OS(Str);
OS << "kill:";
for (const MachineOperand &Op : MI->operands()) {
assert(Op.isReg() && "KILL instruction must have only register operands");
OS << ' ' << (Op.isDef() ? "def " : "killed ")
<< printReg(Op.getReg(), AP.MF->getSubtarget().getRegisterInfo());
}
AP.OutStreamer->AddComment(OS.str());
AP.OutStreamer->addBlankLine();
}
/// emitDebugValueComment - This method handles the target-independent form
/// of DBG_VALUE, returning true if it was able to do so. A false return
/// means the target will need to handle MI in EmitInstruction.
static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
// This code handles only the 4-operand target-independent form.
if (MI->isNonListDebugValue() && MI->getNumOperands() != 4)
return false;
SmallString<128> Str;
raw_svector_ostream OS(Str);
OS << "DEBUG_VALUE: ";
const DILocalVariable *V = MI->getDebugVariable();
if (auto *SP = dyn_cast<DISubprogram>(V->getScope())) {
StringRef Name = SP->getName();
if (!Name.empty())
OS << Name << ":";
}
OS << V->getName();
OS << " <- ";
const DIExpression *Expr = MI->getDebugExpression();
// First convert this to a non-variadic expression if possible, to simplify
// the output.
if (auto NonVariadicExpr = DIExpression::convertToNonVariadicExpression(Expr))
Expr = *NonVariadicExpr;
// Then, output the possibly-simplified expression.
if (Expr->getNumElements()) {
OS << '[';
ListSeparator LS;
for (auto &Op : Expr->expr_ops()) {
OS << LS << dwarf::OperationEncodingString(Op.getOp());
for (unsigned I = 0; I < Op.getNumArgs(); ++I)
OS << ' ' << Op.getArg(I);
}
OS << "] ";
}
// Register or immediate value. Register 0 means undef.
for (const MachineOperand &Op : MI->debug_operands()) {
if (&Op != MI->debug_operands().begin())
OS << ", ";
switch (Op.getType()) {
case MachineOperand::MO_FPImmediate: {
APFloat APF = APFloat(Op.getFPImm()->getValueAPF());
Type *ImmTy = Op.getFPImm()->getType();
if (ImmTy->isBFloatTy() || ImmTy->isHalfTy() || ImmTy->isFloatTy() ||
ImmTy->isDoubleTy()) {
OS << APF.convertToDouble();
} else {
// There is no good way to print long double. Convert a copy to
// double. Ah well, it's only a comment.
bool ignored;
APF.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
&ignored);
OS << "(long double) " << APF.convertToDouble();
}
break;
}
case MachineOperand::MO_Immediate: {
OS << Op.getImm();
break;
}
case MachineOperand::MO_CImmediate: {
Op.getCImm()->getValue().print(OS, false /*isSigned*/);
break;
}
case MachineOperand::MO_TargetIndex: {
OS << "!target-index(" << Op.getIndex() << "," << Op.getOffset() << ")";
break;
}
case MachineOperand::MO_Register:
case MachineOperand::MO_FrameIndex: {
Register Reg;
std::optional<StackOffset> Offset;
if (Op.isReg()) {
Reg = Op.getReg();
} else {
const TargetFrameLowering *TFI =
AP.MF->getSubtarget().getFrameLowering();
Offset = TFI->getFrameIndexReference(*AP.MF, Op.getIndex(), Reg);
}
if (!Reg) {
// Suppress offset, it is not meaningful here.
OS << "undef";
break;
}
// The second operand is only an offset if it's an immediate.
if (MI->isIndirectDebugValue())
Offset = StackOffset::getFixed(MI->getDebugOffset().getImm());
if (Offset)
OS << '[';
OS << printReg(Reg, AP.MF->getSubtarget().getRegisterInfo());
if (Offset)
OS << '+' << Offset->getFixed() << ']';
break;
}
default:
llvm_unreachable("Unknown operand type");
}
}
// NOTE: Want this comment at start of line, don't emit with AddComment.
AP.OutStreamer->emitRawComment(OS.str());
return true;
}
/// This method handles the target-independent form of DBG_LABEL, returning
/// true if it was able to do so. A false return means the target will need
/// to handle MI in EmitInstruction.
static bool emitDebugLabelComment(const MachineInstr *MI, AsmPrinter &AP) {
if (MI->getNumOperands() != 1)
return false;
SmallString<128> Str;
raw_svector_ostream OS(Str);
OS << "DEBUG_LABEL: ";
const DILabel *V = MI->getDebugLabel();
if (auto *SP = dyn_cast<DISubprogram>(
V->getScope()->getNonLexicalBlockFileScope())) {
StringRef Name = SP->getName();
if (!Name.empty())
OS << Name << ":";
}
OS << V->getName();
// NOTE: Want this comment at start of line, don't emit with AddComment.
AP.OutStreamer->emitRawComment(OS.str());
return true;
}
AsmPrinter::CFISection
AsmPrinter::getFunctionCFISectionType(const Function &F) const {
// Ignore functions that won't get emitted.
if (F.isDeclarationForLinker())
return CFISection::None;
if (MAI->getExceptionHandlingType() == ExceptionHandling::DwarfCFI &&
F.needsUnwindTableEntry())
return CFISection::EH;
if (MMI->hasDebugInfo() || TM.Options.ForceDwarfFrameSection)
return CFISection::Debug;
return CFISection::None;
}
AsmPrinter::CFISection
AsmPrinter::getFunctionCFISectionType(const MachineFunction &MF) const {
return getFunctionCFISectionType(MF.getFunction());
}
bool AsmPrinter::needsSEHMoves() {
return MAI->usesWindowsCFI() && MF->getFunction().needsUnwindTableEntry();
}
bool AsmPrinter::needsCFIForDebug() const {
return MAI->getExceptionHandlingType() == ExceptionHandling::None &&
MAI->doesUseCFIForDebug() && ModuleCFISection == CFISection::Debug;
}
void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) {
ExceptionHandling ExceptionHandlingType = MAI->getExceptionHandlingType();
if (!needsCFIForDebug() &&
ExceptionHandlingType != ExceptionHandling::DwarfCFI &&
ExceptionHandlingType != ExceptionHandling::ARM)
return;
if (getFunctionCFISectionType(*MF) == CFISection::None)
return;
// If there is no "real" instruction following this CFI instruction, skip
// emitting it; it would be beyond the end of the function's FDE range.
auto *MBB = MI.getParent();
auto I = std::next(MI.getIterator());
while (I != MBB->end() && I->isTransient())
++I;
if (I == MBB->instr_end() &&
MBB->getReverseIterator() == MBB->getParent()->rbegin())
return;
const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();
unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
const MCCFIInstruction &CFI = Instrs[CFIIndex];
emitCFIInstruction(CFI);
}
void AsmPrinter::emitFrameAlloc(const MachineInstr &MI) {
// The operands are the MCSymbol and the frame offset of the allocation.
MCSymbol *FrameAllocSym = MI.getOperand(0).getMCSymbol();
int FrameOffset = MI.getOperand(1).getImm();
// Emit a symbol assignment.
OutStreamer->emitAssignment(FrameAllocSym,
MCConstantExpr::create(FrameOffset, OutContext));
}
/// Returns the BB metadata to be emitted in the .llvm_bb_addr_map section for a
/// given basic block. This can be used to capture more precise profile
/// information. We use the last 4 bits (LSBs) to encode the following
/// information:
/// * (1): set if return block (ret or tail call).
/// * (2): set if ends with a tail call.
/// * (3): set if exception handling (EH) landing pad.
/// * (4): set if the block can fall through to its next.
/// The remaining bits are zero.
static unsigned getBBAddrMapMetadata(const MachineBasicBlock &MBB) {
const TargetInstrInfo *TII = MBB.getParent()->getSubtarget().getInstrInfo();
return ((unsigned)MBB.isReturnBlock()) |
((!MBB.empty() && TII->isTailCall(MBB.back())) << 1) |
(MBB.isEHPad() << 2) |
(const_cast<MachineBasicBlock &>(MBB).canFallThrough() << 3);
}
void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
MCSection *BBAddrMapSection =
getObjFileLowering().getBBAddrMapSection(*MF.getSection());
assert(BBAddrMapSection && ".llvm_bb_addr_map section is not initialized.");
const MCSymbol *FunctionSymbol = getFunctionBegin();
OutStreamer->pushSection();
OutStreamer->switchSection(BBAddrMapSection);
OutStreamer->AddComment("version");
uint8_t BBAddrMapVersion = OutStreamer->getContext().getBBAddrMapVersion();
OutStreamer->emitInt8(BBAddrMapVersion);
OutStreamer->AddComment("feature");
OutStreamer->emitInt8(0);
OutStreamer->AddComment("function address");
OutStreamer->emitSymbolValue(FunctionSymbol, getPointerSize());
OutStreamer->AddComment("number of basic blocks");
OutStreamer->emitULEB128IntValue(MF.size());
const MCSymbol *PrevMBBEndSymbol = FunctionSymbol;
// Emit BB Information for each basic block in the funciton.
for (const MachineBasicBlock &MBB : MF) {
const MCSymbol *MBBSymbol =
MBB.isEntryBlock() ? FunctionSymbol : MBB.getSymbol();
// TODO: Remove this check when version 1 is deprecated.
if (BBAddrMapVersion > 1) {
OutStreamer->AddComment("BB id");
// Emit the BB ID for this basic block.
OutStreamer->emitULEB128IntValue(*MBB.getBBID());
}
// Emit the basic block offset relative to the end of the previous block.
// This is zero unless the block is padded due to alignment.
emitLabelDifferenceAsULEB128(MBBSymbol, PrevMBBEndSymbol);
// Emit the basic block size. When BBs have alignments, their size cannot
// always be computed from their offsets.
emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), MBBSymbol);
// Emit the Metadata.
OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
PrevMBBEndSymbol = MBB.getEndSymbol();
}
OutStreamer->popSection();
}
void AsmPrinter::emitKCFITrapEntry(const MachineFunction &MF,
const MCSymbol *Symbol) {
MCSection *Section =
getObjFileLowering().getKCFITrapSection(*MF.getSection());
if (!Section)
return;
OutStreamer->pushSection();
OutStreamer->switchSection(Section);
MCSymbol *Loc = OutContext.createLinkerPrivateTempSymbol();
OutStreamer->emitLabel(Loc);
OutStreamer->emitAbsoluteSymbolDiff(Symbol, Loc, 4);
OutStreamer->popSection();
}
void AsmPrinter::emitKCFITypeId(const MachineFunction &MF) {
const Function &F = MF.getFunction();
if (const MDNode *MD = F.getMetadata(LLVMContext::MD_kcfi_type))
emitGlobalConstant(F.getParent()->getDataLayout(),
mdconst::extract<ConstantInt>(MD->getOperand(0)));
}
void AsmPrinter::emitPseudoProbe(const MachineInstr &MI) {
if (PP) {
auto GUID = MI.getOperand(0).getImm();
auto Index = MI.getOperand(1).getImm();
auto Type = MI.getOperand(2).getImm();
auto Attr = MI.getOperand(3).getImm();
DILocation *DebugLoc = MI.getDebugLoc();
PP->emitPseudoProbe(GUID, Index, Type, Attr, DebugLoc);
}
}
void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
if (!MF.getTarget().Options.EmitStackSizeSection)
return;
MCSection *StackSizeSection =
getObjFileLowering().getStackSizesSection(*getCurrentSection());
if (!StackSizeSection)
return;
const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
// Don't emit functions with dynamic stack allocations.
if (FrameInfo.hasVarSizedObjects())
return;
OutStreamer->pushSection();
OutStreamer->switchSection(StackSizeSection);
const MCSymbol *FunctionSymbol = getFunctionBegin();
uint64_t StackSize =
FrameInfo.getStackSize() + FrameInfo.getUnsafeStackSize();
OutStreamer->emitSymbolValue(FunctionSymbol, TM.getProgramPointerSize());
OutStreamer->emitULEB128IntValue(StackSize);
OutStreamer->popSection();
}
void AsmPrinter::emitStackUsage(const MachineFunction &MF) {
const std::string &OutputFilename = MF.getTarget().Options.StackUsageOutput;
// OutputFilename empty implies -fstack-usage is not passed.
if (OutputFilename.empty())
return;
const MachineFrameInfo &FrameInfo = MF.getFrameInfo();
uint64_t StackSize =
FrameInfo.getStackSize() + FrameInfo.getUnsafeStackSize();
if (StackUsageStream == nullptr) {
std::error_code EC;
StackUsageStream =
std::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::OF_Text);
if (EC) {
errs() << "Could not open file: " << EC.message();
return;
}
}
*StackUsageStream << MF.getFunction().getParent()->getName();
if (const DISubprogram *DSP = MF.getFunction().getSubprogram())
*StackUsageStream << ':' << DSP->getLine();
*StackUsageStream << ':' << MF.getName() << '\t' << StackSize << '\t';
if (FrameInfo.hasVarSizedObjects())
*StackUsageStream << "dynamic\n";
else
*StackUsageStream << "static\n";
}
void AsmPrinter::emitPCSectionsLabel(const MachineFunction &MF,
const MDNode &MD) {
MCSymbol *S = MF.getContext().createTempSymbol("pcsection");
OutStreamer->emitLabel(S);
PCSectionsSymbols[&MD].emplace_back(S);
}
void AsmPrinter::emitPCSections(const MachineFunction &MF) {
const Function &F = MF.getFunction();
if (PCSectionsSymbols.empty() && !F.hasMetadata(LLVMContext::MD_pcsections))
return;
const CodeModel::Model CM = MF.getTarget().getCodeModel();
const unsigned RelativeRelocSize =
(CM == CodeModel::Medium || CM == CodeModel::Large) ? getPointerSize()
: 4;
// Switch to PCSection, short-circuiting the common case where the current
// section is still valid (assume most MD_pcsections contain just 1 section).
auto SwitchSection = [&, Prev = StringRef()](const StringRef &Sec) mutable {
if (Sec == Prev)
return;
MCSection *S = getObjFileLowering().getPCSection(Sec, MF.getSection());
assert(S && "PC section is not initialized");
OutStreamer->switchSection(S);
Prev = Sec;
};
// Emit symbols into sections and data as specified in the pcsections MDNode.
auto EmitForMD = [&](const MDNode &MD, ArrayRef<const MCSymbol *> Syms,
bool Deltas) {
// Expect the first operand to be a section name. After that, a tuple of
// constants may appear, which will simply be emitted into the current
// section (the user of MD_pcsections decides the format of encoded data).
assert(isa<MDString>(MD.getOperand(0)) && "first operand not a string");
for (const MDOperand &MDO : MD.operands()) {
if (auto *S = dyn_cast<MDString>(MDO)) {
SwitchSection(S->getString());
const MCSymbol *Prev = Syms.front();
for (const MCSymbol *Sym : Syms) {
if (Sym == Prev || !Deltas) {
// Use the entry itself as the base of the relative offset.
MCSymbol *Base = MF.getContext().createTempSymbol("pcsection_base");
OutStreamer->emitLabel(Base);
// Emit relative relocation `addr - base`, which avoids a dynamic
// relocation in the final binary. User will get the address with
// `base + addr`.
emitLabelDifference(Sym, Base, RelativeRelocSize);
} else {
emitLabelDifference(Sym, Prev, 4);
}
Prev = Sym;
}
} else {
assert(isa<MDNode>(MDO) && "expecting either string or tuple");
const auto *AuxMDs = cast<MDNode>(MDO);
for (const MDOperand &AuxMDO : AuxMDs->operands()) {
assert(isa<ConstantAsMetadata>(AuxMDO) && "expecting a constant");
const auto *C = cast<ConstantAsMetadata>(AuxMDO);
emitGlobalConstant(F.getParent()->getDataLayout(), C->getValue());
}
}
}
};
OutStreamer->pushSection();
// Emit PCs for function start and function size.
if (const MDNode *MD = F.getMetadata(LLVMContext::MD_pcsections))
EmitForMD(*MD, {getFunctionBegin(), getFunctionEnd()}, true);
// Emit PCs for instructions collected.
for (const auto &MS : PCSectionsSymbols)
EmitForMD(*MS.first, MS.second, false);
OutStreamer->popSection();
PCSectionsSymbols.clear();
}
/// Returns true if function begin and end labels should be emitted.
static bool needFuncLabels(const MachineFunction &MF) {
MachineModuleInfo &MMI = MF.getMMI();
if (!MF.getLandingPads().empty() || MF.hasEHFunclets() ||
MMI.hasDebugInfo() ||
MF.getFunction().hasMetadata(LLVMContext::MD_pcsections))
return true;
// We might emit an EH table that uses function begin and end labels even if
// we don't have any landingpads.
if (!MF.getFunction().hasPersonalityFn())
return false;
return !isNoOpWithoutInvoke(
classifyEHPersonality(MF.getFunction().getPersonalityFn()));
}
/// EmitFunctionBody - This method emits the body and trailer for a
/// function.
void AsmPrinter::emitFunctionBody() {
emitFunctionHeader();
// Emit target-specific gunk before the function body.
emitFunctionBodyStart();
if (isVerbose()) {
// Get MachineDominatorTree or compute it on the fly if it's unavailable
MDT = getAnalysisIfAvailable<MachineDominatorTree>();
if (!MDT) {
OwnedMDT = std::make_unique<MachineDominatorTree>();
OwnedMDT->getBase().recalculate(*MF);
MDT = OwnedMDT.get();
}
// Get MachineLoopInfo or compute it on the fly if it's unavailable
MLI = getAnalysisIfAvailable<MachineLoopInfo>();
if (!MLI) {
OwnedMLI = std::make_unique<MachineLoopInfo>();
OwnedMLI->getBase().analyze(MDT->getBase());
MLI = OwnedMLI.get();
}
}
// Print out code for the function.
bool HasAnyRealCode = false;
int NumInstsInFunction = 0;
bool CanDoExtraAnalysis = ORE->allowExtraAnalysis(DEBUG_TYPE);
for (auto &MBB : *MF) {
// Print a label for the basic block.
emitBasicBlockStart(MBB);
DenseMap<StringRef, unsigned> MnemonicCounts;
for (auto &MI : MBB) {
// Print the assembly for the instruction.
if (!MI.isPosition() && !MI.isImplicitDef() && !MI.isKill() &&
!MI.isDebugInstr()) {
HasAnyRealCode = true;
++NumInstsInFunction;
}
// If there is a pre-instruction symbol, emit a label for it here.
if (MCSymbol *S = MI.getPreInstrSymbol())
OutStreamer->emitLabel(S);
if (MDNode *MD = MI.getPCSections())
emitPCSectionsLabel(*MF, *MD);
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->beginInstruction(&MI);
}
if (isVerbose())
emitComments(MI, OutStreamer->getCommentOS());
switch (MI.getOpcode()) {
case TargetOpcode::CFI_INSTRUCTION:
emitCFIInstruction(MI);
break;
case TargetOpcode::LOCAL_ESCAPE:
emitFrameAlloc(MI);
break;
case TargetOpcode::ANNOTATION_LABEL:
case TargetOpcode::EH_LABEL:
case TargetOpcode::GC_LABEL:
OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol());
break;
case TargetOpcode::INLINEASM:
case TargetOpcode::INLINEASM_BR:
emitInlineAsm(&MI);
break;
case TargetOpcode::DBG_VALUE:
case TargetOpcode::DBG_VALUE_LIST:
if (isVerbose()) {
if (!emitDebugValueComment(&MI, *this))
emitInstruction(&MI);
}
break;
case TargetOpcode::DBG_INSTR_REF:
// This instruction reference will have been resolved to a machine
// location, and a nearby DBG_VALUE created. We can safely ignore
// the instruction reference.
break;
case TargetOpcode::DBG_PHI:
// This instruction is only used to label a program point, it's purely
// meta information.
break;
case TargetOpcode::DBG_LABEL:
if (isVerbose()) {
if (!emitDebugLabelComment(&MI, *this))
emitInstruction(&MI);
}
break;
case TargetOpcode::IMPLICIT_DEF:
if (isVerbose()) emitImplicitDef(&MI);
break;
case TargetOpcode::KILL:
if (isVerbose()) emitKill(&MI, *this);
break;
case TargetOpcode::PSEUDO_PROBE:
emitPseudoProbe(MI);
break;
case TargetOpcode::ARITH_FENCE:
if (isVerbose())
OutStreamer->emitRawComment("ARITH_FENCE");
break;
case TargetOpcode::MEMBARRIER:
OutStreamer->emitRawComment("MEMBARRIER");
break;
default:
emitInstruction(&MI);
if (CanDoExtraAnalysis) {
MCInst MCI;
MCI.setOpcode(MI.getOpcode());
auto Name = OutStreamer->getMnemonic(MCI);
auto I = MnemonicCounts.insert({Name, 0u});
I.first->second++;
}
break;
}
// If there is a post-instruction symbol, emit a label for it here.
if (MCSymbol *S = MI.getPostInstrSymbol())
OutStreamer->emitLabel(S);
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->endInstruction();
}
}
// We must emit temporary symbol for the end of this basic block, if either
// we have BBLabels enabled or if this basic blocks marks the end of a
// section.
if (MF->hasBBLabels() ||
(MAI->hasDotTypeDotSizeDirective() && MBB.isEndSection()))
OutStreamer->emitLabel(MBB.getEndSymbol());
if (MBB.isEndSection()) {
// The size directive for the section containing the entry block is
// handled separately by the function section.
if (!MBB.sameSection(&MF->front())) {
if (MAI->hasDotTypeDotSizeDirective()) {
// Emit the size directive for the basic block section.
const MCExpr *SizeExp = MCBinaryExpr::createSub(
MCSymbolRefExpr::create(MBB.getEndSymbol(), OutContext),
MCSymbolRefExpr::create(CurrentSectionBeginSym, OutContext),
OutContext);
OutStreamer->emitELFSize(CurrentSectionBeginSym, SizeExp);
}
MBBSectionRanges[MBB.getSectionIDNum()] =
MBBSectionRange{CurrentSectionBeginSym, MBB.getEndSymbol()};
}
}
emitBasicBlockEnd(MBB);
if (CanDoExtraAnalysis) {
// Skip empty blocks.
if (MBB.empty())
continue;
MachineOptimizationRemarkAnalysis R(DEBUG_TYPE, "InstructionMix",
MBB.begin()->getDebugLoc(), &MBB);
// Generate instruction mix remark. First, sort counts in descending order
// by count and name.
SmallVector<std::pair<StringRef, unsigned>, 128> MnemonicVec;
for (auto &KV : MnemonicCounts)
MnemonicVec.emplace_back(KV.first, KV.second);
sort(MnemonicVec, [](const std::pair<StringRef, unsigned> &A,
const std::pair<StringRef, unsigned> &B) {
if (A.second > B.second)
return true;
if (A.second == B.second)
return StringRef(A.first) < StringRef(B.first);
return false;
});
R << "BasicBlock: " << ore::NV("BasicBlock", MBB.getName()) << "\n";
for (auto &KV : MnemonicVec) {
auto Name = (Twine("INST_") + getToken(KV.first.trim()).first).str();
R << KV.first << ": " << ore::NV(Name, KV.second) << "\n";
}
ORE->emit(R);
}
}
EmittedInsts += NumInstsInFunction;
MachineOptimizationRemarkAnalysis R(DEBUG_TYPE, "InstructionCount",
MF->getFunction().getSubprogram(),
&MF->front());
R << ore::NV("NumInstructions", NumInstsInFunction)
<< " instructions in function";
ORE->emit(R);
// If the function is empty and the object file uses .subsections_via_symbols,
// then we need to emit *something* to the function body to prevent the
// labels from collapsing together. Just emit a noop.
// Similarly, don't emit empty functions on Windows either. It can lead to
// duplicate entries (two functions with the same RVA) in the Guard CF Table
// after linking, causing the kernel not to load the binary:
// https://developercommunity.visualstudio.com/content/problem/45366/vc-linker-creates-invalid-dll-with-clang-cl.html
// FIXME: Hide this behind some API in e.g. MCAsmInfo or MCTargetStreamer.
const Triple &TT = TM.getTargetTriple();
if (!HasAnyRealCode && (MAI->hasSubsectionsViaSymbols() ||
(TT.isOSWindows() && TT.isOSBinFormatCOFF()))) {
MCInst Noop = MF->getSubtarget().getInstrInfo()->getNop();
// Targets can opt-out of emitting the noop here by leaving the opcode
// unspecified.
if (Noop.getOpcode()) {
OutStreamer->AddComment("avoids zero-length function");
emitNops(1);
}
}
// Switch to the original section in case basic block sections was used.
OutStreamer->switchSection(MF->getSection());
const Function &F = MF->getFunction();
for (const auto &BB : F) {
if (!BB.hasAddressTaken())
continue;
MCSymbol *Sym = GetBlockAddressSymbol(&BB);
if (Sym->isDefined())
continue;
OutStreamer->AddComment("Address of block that was removed by CodeGen");
OutStreamer->emitLabel(Sym);
}
// Emit target-specific gunk after the function body.
emitFunctionBodyEnd();
// Even though wasm supports .type and .size in general, function symbols
// are automatically sized.
bool EmitFunctionSize = MAI->hasDotTypeDotSizeDirective() && !TT.isWasm();
if (needFuncLabels(*MF) || EmitFunctionSize) {
// Create a symbol for the end of function.
CurrentFnEnd = createTempSymbol("func_end");
OutStreamer->emitLabel(CurrentFnEnd);
}
// If the target wants a .size directive for the size of the function, emit
// it.
if (EmitFunctionSize) {
// We can get the size as difference between the function label and the
// temp label.
const MCExpr *SizeExp = MCBinaryExpr::createSub(
MCSymbolRefExpr::create(CurrentFnEnd, OutContext),
MCSymbolRefExpr::create(CurrentFnSymForSize, OutContext), OutContext);
OutStreamer->emitELFSize(CurrentFnSym, SizeExp);
if (CurrentFnBeginLocal)
OutStreamer->emitELFSize(CurrentFnBeginLocal, SizeExp);
}
// Call endBasicBlockSection on the last block now, if it wasn't already
// called.
if (!MF->back().isEndSection()) {
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->endBasicBlockSection(MF->back());
}
}
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->markFunctionEnd();
}
MBBSectionRanges[MF->front().getSectionIDNum()] =
MBBSectionRange{CurrentFnBegin, CurrentFnEnd};
// Print out jump tables referenced by the function.
emitJumpTableInfo();
// Emit post-function debug and/or EH information.
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->endFunction(MF);
}
// Emit section containing BB address offsets and their metadata, when
// BB labels are requested for this function. Skip empty functions.
if (MF->hasBBLabels() && HasAnyRealCode)
emitBBAddrMapSection(*MF);
// Emit sections containing instruction and function PCs.
emitPCSections(*MF);
// Emit section containing stack size metadata.
emitStackSizeSection(*MF);
// Emit .su file containing function stack size information.
emitStackUsage(*MF);
emitPatchableFunctionEntries();
if (isVerbose())
OutStreamer->getCommentOS() << "-- End function\n";
OutStreamer->addBlankLine();
}
/// Compute the number of Global Variables that uses a Constant.
static unsigned getNumGlobalVariableUses(const Constant *C) {
if (!C)
return 0;
if (isa<GlobalVariable>(C))
return 1;
unsigned NumUses = 0;
for (const auto *CU : C->users())
NumUses += getNumGlobalVariableUses(dyn_cast<Constant>(CU));
return NumUses;
}
/// Only consider global GOT equivalents if at least one user is a
/// cstexpr inside an initializer of another global variables. Also, don't
/// handle cstexpr inside instructions. During global variable emission,
/// candidates are skipped and are emitted later in case at least one cstexpr
/// isn't replaced by a PC relative GOT entry access.
static bool isGOTEquivalentCandidate(const GlobalVariable *GV,
unsigned &NumGOTEquivUsers) {
// Global GOT equivalents are unnamed private globals with a constant
// pointer initializer to another global symbol. They must point to a
// GlobalVariable or Function, i.e., as GlobalValue.
if (!GV->hasGlobalUnnamedAddr() || !GV->hasInitializer() ||
!GV->isConstant() || !GV->isDiscardableIfUnused() ||
!isa<GlobalValue>(GV->getOperand(0)))
return false;
// To be a got equivalent, at least one of its users need to be a constant
// expression used by another global variable.
for (const auto *U : GV->users())
NumGOTEquivUsers += getNumGlobalVariableUses(dyn_cast<Constant>(U));
return NumGOTEquivUsers > 0;
}
/// Unnamed constant global variables solely contaning a pointer to
/// another globals variable is equivalent to a GOT table entry; it contains the
/// the address of another symbol. Optimize it and replace accesses to these
/// "GOT equivalents" by using the GOT entry for the final global instead.
/// Compute GOT equivalent candidates among all global variables to avoid
/// emitting them if possible later on, after it use is replaced by a GOT entry
/// access.
void AsmPrinter::computeGlobalGOTEquivs(Module &M) {
if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
return;
for (const auto &G : M.globals()) {
unsigned NumGOTEquivUsers = 0;
if (!isGOTEquivalentCandidate(&G, NumGOTEquivUsers))
continue;
const MCSymbol *GOTEquivSym = getSymbol(&G);
GlobalGOTEquivs[GOTEquivSym] = std::make_pair(&G, NumGOTEquivUsers);
}
}
/// Constant expressions using GOT equivalent globals may not be eligible
/// for PC relative GOT entry conversion, in such cases we need to emit such
/// globals we previously omitted in EmitGlobalVariable.
void AsmPrinter::emitGlobalGOTEquivs() {
if (!getObjFileLowering().supportIndirectSymViaGOTPCRel())
return;
SmallVector<const GlobalVariable *, 8> FailedCandidates;
for (auto &I : GlobalGOTEquivs) {
const GlobalVariable *GV = I.second.first;
unsigned Cnt = I.second.second;
if (Cnt)
FailedCandidates.push_back(GV);
}
GlobalGOTEquivs.clear();
for (const auto *GV : FailedCandidates)
emitGlobalVariable(GV);
}
void AsmPrinter::emitGlobalAlias(Module &M, const GlobalAlias &GA) {
MCSymbol *Name = getSymbol(&GA);
bool IsFunction = GA.getValueType()->isFunctionTy();
// Treat bitcasts of functions as functions also. This is important at least
// on WebAssembly where object and function addresses can't alias each other.
if (!IsFunction)
IsFunction = isa<Function>(GA.getAliasee()->stripPointerCasts());
// AIX's assembly directive `.set` is not usable for aliasing purpose,
// so AIX has to use the extra-label-at-definition strategy. At this
// point, all the extra label is emitted, we just have to emit linkage for
// those labels.
if (TM.getTargetTriple().isOSBinFormatXCOFF()) {
assert(MAI->hasVisibilityOnlyWithLinkage() &&
"Visibility should be handled with emitLinkage() on AIX.");
// Linkage for alias of global variable has been emitted.
if (isa<GlobalVariable>(GA.getAliaseeObject()))
return;
emitLinkage(&GA, Name);
// If it's a function, also emit linkage for aliases of function entry
// point.
if (IsFunction)
emitLinkage(&GA,
getObjFileLowering().getFunctionEntryPointSymbol(&GA, TM));
return;
}
if (GA.hasExternalLinkage() || !MAI->getWeakRefDirective())
OutStreamer->emitSymbolAttribute(Name, MCSA_Global);
else if (GA.hasWeakLinkage() || GA.hasLinkOnceLinkage())
OutStreamer->emitSymbolAttribute(Name, MCSA_WeakReference);
else
assert(GA.hasLocalLinkage() && "Invalid alias linkage");
// Set the symbol type to function if the alias has a function type.
// This affects codegen when the aliasee is not a function.
if (IsFunction) {
OutStreamer->emitSymbolAttribute(Name, MCSA_ELF_TypeFunction);
if (TM.getTargetTriple().isOSBinFormatCOFF()) {
OutStreamer->beginCOFFSymbolDef(Name);
OutStreamer->emitCOFFSymbolStorageClass(
GA.hasLocalLinkage() ? COFF::IMAGE_SYM_CLASS_STATIC
: COFF::IMAGE_SYM_CLASS_EXTERNAL);
OutStreamer->emitCOFFSymbolType(COFF::IMAGE_SYM_DTYPE_FUNCTION
<< COFF::SCT_COMPLEX_TYPE_SHIFT);
OutStreamer->endCOFFSymbolDef();
}
}
emitVisibility(Name, GA.getVisibility());
const MCExpr *Expr = lowerConstant(GA.getAliasee());
if (MAI->hasAltEntry() && isa<MCBinaryExpr>(Expr))
OutStreamer->emitSymbolAttribute(Name, MCSA_AltEntry);
// Emit the directives as assignments aka .set:
OutStreamer->emitAssignment(Name, Expr);
MCSymbol *LocalAlias = getSymbolPreferLocal(GA);
if (LocalAlias != Name)
OutStreamer->emitAssignment(LocalAlias, Expr);
// If the aliasee does not correspond to a symbol in the output, i.e. the
// alias is not of an object or the aliased object is private, then set the
// size of the alias symbol from the type of the alias. We don't do this in
// other situations as the alias and aliasee having differing types but same
// size may be intentional.
const GlobalObject *BaseObject = GA.getAliaseeObject();
if (MAI->hasDotTypeDotSizeDirective() && GA.getValueType()->isSized() &&
(!BaseObject || BaseObject->hasPrivateLinkage())) {
const DataLayout &DL = M.getDataLayout();
uint64_t Size = DL.getTypeAllocSize(GA.getValueType());
OutStreamer->emitELFSize(Name, MCConstantExpr::create(Size, OutContext));
}
}
void AsmPrinter::emitGlobalIFunc(Module &M, const GlobalIFunc &GI) {
assert(!TM.getTargetTriple().isOSBinFormatXCOFF() &&
"IFunc is not supported on AIX.");
MCSymbol *Name = getSymbol(&GI);
if (GI.hasExternalLinkage() || !MAI->getWeakRefDirective())
OutStreamer->emitSymbolAttribute(Name, MCSA_Global);
else if (GI.hasWeakLinkage() || GI.hasLinkOnceLinkage())
OutStreamer->emitSymbolAttribute(Name, MCSA_WeakReference);
else
assert(GI.hasLocalLinkage() && "Invalid ifunc linkage");
OutStreamer->emitSymbolAttribute(Name, MCSA_ELF_TypeIndFunction);
emitVisibility(Name, GI.getVisibility());
// Emit the directives as assignments aka .set:
const MCExpr *Expr = lowerConstant(GI.getResolver());
OutStreamer->emitAssignment(Name, Expr);
MCSymbol *LocalAlias = getSymbolPreferLocal(GI);
if (LocalAlias != Name)
OutStreamer->emitAssignment(LocalAlias, Expr);
}
void AsmPrinter::emitRemarksSection(remarks::RemarkStreamer &RS) {
if (!RS.needsSection())
return;
remarks::RemarkSerializer &RemarkSerializer = RS.getSerializer();
std::optional<SmallString<128>> Filename;
if (std::optional<StringRef> FilenameRef = RS.getFilename()) {
Filename = *FilenameRef;
sys::fs::make_absolute(*Filename);
assert(!Filename->empty() && "The filename can't be empty.");
}
std::string Buf;
raw_string_ostream OS(Buf);
std::unique_ptr<remarks::MetaSerializer> MetaSerializer =
Filename ? RemarkSerializer.metaSerializer(OS, Filename->str())
: RemarkSerializer.metaSerializer(OS);
MetaSerializer->emit();
// Switch to the remarks section.
MCSection *RemarksSection =
OutContext.getObjectFileInfo()->getRemarksSection();
OutStreamer->switchSection(RemarksSection);
OutStreamer->emitBinaryData(OS.str());
}
bool AsmPrinter::doFinalization(Module &M) {
// Set the MachineFunction to nullptr so that we can catch attempted
// accesses to MF specific features at the module level and so that
// we can conditionalize accesses based on whether or not it is nullptr.
MF = nullptr;
// Gather all GOT equivalent globals in the module. We really need two
// passes over the globals: one to compute and another to avoid its emission
// in EmitGlobalVariable, otherwise we would not be able to handle cases
// where the got equivalent shows up before its use.
computeGlobalGOTEquivs(M);
// Emit global variables.
for (const auto &G : M.globals())
emitGlobalVariable(&G);
// Emit remaining GOT equivalent globals.
emitGlobalGOTEquivs();
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
// Emit linkage(XCOFF) and visibility info for declarations
for (const Function &F : M) {
if (!F.isDeclarationForLinker())
continue;
MCSymbol *Name = getSymbol(&F);
// Function getSymbol gives us the function descriptor symbol for XCOFF.
if (!TM.getTargetTriple().isOSBinFormatXCOFF()) {
GlobalValue::VisibilityTypes V = F.getVisibility();
if (V == GlobalValue::DefaultVisibility)
continue;
emitVisibility(Name, V, false);
continue;
}
if (F.isIntrinsic())
continue;
// Handle the XCOFF case.
// Variable `Name` is the function descriptor symbol (see above). Get the
// function entry point symbol.
MCSymbol *FnEntryPointSym = TLOF.getFunctionEntryPointSymbol(&F, TM);
// Emit linkage for the function entry point.
emitLinkage(&F, FnEntryPointSym);
// Emit linkage for the function descriptor.
emitLinkage(&F, Name);
}
// Emit the remarks section contents.
// FIXME: Figure out when is the safest time to emit this section. It should
// not come after debug info.
if (remarks::RemarkStreamer *RS = M.getContext().getMainRemarkStreamer())
emitRemarksSection(*RS);
TLOF.emitModuleMetadata(*OutStreamer, M);
if (TM.getTargetTriple().isOSBinFormatELF()) {
MachineModuleInfoELF &MMIELF = MMI->getObjFileInfo<MachineModuleInfoELF>();
// Output stubs for external and common global variables.
MachineModuleInfoELF::SymbolListTy Stubs = MMIELF.GetGVStubList();
if (!Stubs.empty()) {
OutStreamer->switchSection(TLOF.getDataSection());
const DataLayout &DL = M.getDataLayout();
emitAlignment(Align(DL.getPointerSize()));
for (const auto &Stub : Stubs) {
OutStreamer->emitLabel(Stub.first);
OutStreamer->emitSymbolValue(Stub.second.getPointer(),
DL.getPointerSize());
}
}
}
if (TM.getTargetTriple().isOSBinFormatCOFF()) {
MachineModuleInfoCOFF &MMICOFF =
MMI->getObjFileInfo<MachineModuleInfoCOFF>();
// Output stubs for external and common global variables.
MachineModuleInfoCOFF::SymbolListTy Stubs = MMICOFF.GetGVStubList();
if (!Stubs.empty()) {
const DataLayout &DL = M.getDataLayout();
for (const auto &Stub : Stubs) {
SmallString<256> SectionName = StringRef(".rdata$");
SectionName += Stub.first->getName();
OutStreamer->switchSection(OutContext.getCOFFSection(
SectionName,
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_LNK_COMDAT,
SectionKind::getReadOnly(), Stub.first->getName(),
COFF::IMAGE_COMDAT_SELECT_ANY));
emitAlignment(Align(DL.getPointerSize()));
OutStreamer->emitSymbolAttribute(Stub.first, MCSA_Global);
OutStreamer->emitLabel(Stub.first);
OutStreamer->emitSymbolValue(Stub.second.getPointer(),
DL.getPointerSize());
}
}
}
// This needs to happen before emitting debug information since that can end
// arbitrary sections.
if (auto *TS = OutStreamer->getTargetStreamer())
TS->emitConstantPools();
// Emit Stack maps before any debug info. Mach-O requires that no data or
// text sections come after debug info has been emitted. This matters for
// stack maps as they are arbitrary data, and may even have a custom format
// through user plugins.
emitStackMaps();
// Finalize debug and EH information.
for (const HandlerInfo &HI : Handlers) {
NamedRegionTimer T(HI.TimerName, HI.TimerDescription, HI.TimerGroupName,
HI.TimerGroupDescription, TimePassesIsEnabled);
HI.Handler->endModule();
}
// This deletes all the ephemeral handlers that AsmPrinter added, while
// keeping all the user-added handlers alive until the AsmPrinter is
// destroyed.
Handlers.erase(Handlers.begin() + NumUserHandlers, Handlers.end());
DD = nullptr;
// If the target wants to know about weak references, print them all.
if (MAI->getWeakRefDirective()) {
// FIXME: This is not lazy, it would be nice to only print weak references
// to stuff that is actually used. Note that doing so would require targets
// to notice uses in operands (due to constant exprs etc). This should
// happen with the MC stuff eventually.
// Print out module-level global objects here.
for (const auto &GO : M.global_objects()) {
if (!GO.hasExternalWeakLinkage())
continue;
OutStreamer->emitSymbolAttribute(getSymbol(&GO), MCSA_WeakReference);
}
if (shouldEmitWeakSwiftAsyncExtendedFramePointerFlags()) {
auto SymbolName = "swift_async_extendedFramePointerFlags";
auto Global = M.getGlobalVariable(SymbolName);
if (!Global) {
auto Int8PtrTy = Type::getInt8PtrTy(M.getContext());
Global = new GlobalVariable(M, Int8PtrTy, false,
GlobalValue::ExternalWeakLinkage, nullptr,
SymbolName);
OutStreamer->emitSymbolAttribute(getSymbol(Global), MCSA_WeakReference);
}
}
}
// Print aliases in topological order, that is, for each alias a = b,
// b must be printed before a.
// This is because on some targets (e.g. PowerPC) linker expects aliases in
// such an order to generate correct TOC information.
SmallVector<const GlobalAlias *, 16> AliasStack;
SmallPtrSet<const GlobalAlias *, 16> AliasVisited;
for (const auto &Alias : M.aliases()) {
if (Alias.hasAvailableExternallyLinkage())
continue;
for (const GlobalAlias *Cur = &Alias; Cur;
Cur = dyn_cast<GlobalAlias>(Cur->getAliasee())) {
if (!AliasVisited.insert(Cur).second)
break;
AliasStack.push_back(Cur);
}
for (const GlobalAlias *AncestorAlias : llvm::reverse(AliasStack))
emitGlobalAlias(M, *AncestorAlias);
AliasStack.clear();
}
for (const auto &IFunc : M.ifuncs())
emitGlobalIFunc(M, IFunc);
GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
assert(MI && "AsmPrinter didn't require GCModuleInfo?");
for (GCModuleInfo::iterator I = MI->end(), E = MI->begin(); I != E; )
if (GCMetadataPrinter *MP = getOrCreateGCPrinter(**--I))
MP->finishAssembly(M, *MI, *this);
// Emit llvm.ident metadata in an '.ident' directive.
emitModuleIdents(M);
// Emit bytes for llvm.commandline metadata.
emitModuleCommandLines(M);
// Emit .note.GNU-split-stack and .note.GNU-no-split-stack sections if
// split-stack is used.
if (TM.getTargetTriple().isOSBinFormatELF() && HasSplitStack) {
OutStreamer->switchSection(OutContext.getELFSection(".note.GNU-split-stack",
ELF::SHT_PROGBITS, 0));
if (HasNoSplitStack)
OutStreamer->switchSection(OutContext.getELFSection(
".note.GNU-no-split-stack", ELF::SHT_PROGBITS, 0));
}
// If we don't have any trampolines, then we don't require stack memory
// to be executable. Some targets have a directive to declare this.
Function *InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
if (MCSection *S = MAI->getNonexecutableStackSection(OutContext))
OutStreamer->switchSection(S);
if (TM.Options.EmitAddrsig) {
// Emit address-significance attributes for all globals.
OutStreamer->emitAddrsig();
for (const GlobalValue &GV : M.global_values()) {
if (!GV.use_empty() && !GV.isThreadLocal() &&
!GV.hasDLLImportStorageClass() && !GV.getName().startswith("llvm.") &&
!GV.hasAtLeastLocalUnnamedAddr())
OutStreamer->emitAddrsigSym(getSymbol(&GV));
}
}
// Emit symbol partition specifications (ELF only).
if (TM.getTargetTriple().isOSBinFormatELF()) {
unsigned UniqueID = 0;
for (const GlobalValue &GV : M.global_values()) {
if (!GV.hasPartition() || GV.isDeclarationForLinker() ||
GV.getVisibility() != GlobalValue::DefaultVisibility)
continue;
OutStreamer->switchSection(
OutContext.getELFSection(".llvm_sympart", ELF::SHT_LLVM_SYMPART, 0, 0,
"", false, ++UniqueID, nullptr));
OutStreamer->emitBytes(GV.getPartition());
OutStreamer->emitZeros(1);
OutStreamer->emitValue(
MCSymbolRefExpr::create(getSymbol(&GV), OutContext),
MAI->getCodePointerSize());
}
}
// Allow the target to emit any magic that it wants at the end of the file,
// after everything else has gone out.
emitEndOfAsmFile(M);
MMI = nullptr;
AddrLabelSymbols = nullptr;
OutStreamer->finish();
OutStreamer->reset();
OwnedMLI.reset();
OwnedMDT.reset();
return false;
}
MCSymbol *AsmPrinter::getMBBExceptionSym(const MachineBasicBlock &MBB) {
auto Res = MBBSectionExceptionSyms.try_emplace(MBB.getSectionIDNum());
if (Res.second)
Res.first->second = createTempSymbol("exception");
return Res.first->second;
}
void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
this->MF = &MF;
const Function &F = MF.getFunction();
// Record that there are split-stack functions, so we will emit a special
// section to tell the linker.
if (MF.shouldSplitStack()) {
HasSplitStack = true;
if (!MF.getFrameInfo().needsSplitStackProlog())
HasNoSplitStack = true;
} else
HasNoSplitStack = true;
// Get the function symbol.
if (!MAI->needsFunctionDescriptors()) {
CurrentFnSym = getSymbol(&MF.getFunction());
} else {
assert(TM.getTargetTriple().isOSAIX() &&
"Only AIX uses the function descriptor hooks.");
// AIX is unique here in that the name of the symbol emitted for the
// function body does not have the same name as the source function's
// C-linkage name.
assert(CurrentFnDescSym && "The function descriptor symbol needs to be"
" initalized first.");
// Get the function entry point symbol.
CurrentFnSym = getObjFileLowering().getFunctionEntryPointSymbol(&F, TM);
}
CurrentFnSymForSize = CurrentFnSym;
CurrentFnBegin = nullptr;
CurrentFnBeginLocal = nullptr;
CurrentSectionBeginSym = nullptr;
MBBSectionRanges.clear();
MBBSectionExceptionSyms.clear();
bool NeedsLocalForSize = MAI->needsLocalForSize();
if (F.hasFnAttribute("patchable-function-entry") ||
F.hasFnAttribute("function-instrument") ||
F.hasFnAttribute("xray-instruction-threshold") ||
needFuncLabels(MF) || NeedsLocalForSize ||
MF.getTarget().Options.EmitStackSizeSection || MF.hasBBLabels()) {
CurrentFnBegin = createTempSymbol("func_begin");
if (NeedsLocalForSize)
CurrentFnSymForSize = CurrentFnBegin;
}
ORE = &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE();
}
namespace {
// Keep track the alignment, constpool entries per Section.
struct SectionCPs {
MCSection *S;
Align Alignment;
SmallVector<unsigned, 4> CPEs;
SectionCPs(MCSection *s, Align a) : S(s), Alignment(a) {}
};
} // end anonymous namespace
/// EmitConstantPool - Print to the current output stream assembly
/// representations of the constants in the constant pool MCP. This is
/// used to print out constants which have been "spilled to memory" by
/// the code generator.
void AsmPrinter::emitConstantPool() {
const MachineConstantPool *MCP = MF->getConstantPool();
const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
if (CP.empty()) return;
// Calculate sections for constant pool entries. We collect entries to go into
// the same section together to reduce amount of section switch statements.
SmallVector<SectionCPs, 4> CPSections;
for (unsigned i = 0, e = CP.size(); i != e; ++i) {
const MachineConstantPoolEntry &CPE = CP[i];
Align Alignment = CPE.getAlign();
SectionKind Kind = CPE.getSectionKind(&getDataLayout());
const Constant *C = nullptr;
if (!CPE.isMachineConstantPoolEntry())
C = CPE.Val.ConstVal;
MCSection *S = getObjFileLowering().getSectionForConstant(
getDataLayout(), Kind, C, Alignment);
// The number of sections are small, just do a linear search from the
// last section to the first.
bool Found = false;
unsigned SecIdx = CPSections.size();
while (SecIdx != 0) {
if (CPSections[--SecIdx].S == S) {
Found = true;
break;
}
}
if (!Found) {
SecIdx = CPSections.size();
CPSections.push_back(SectionCPs(S, Alignment));
}
if (Alignment > CPSections[SecIdx].Alignment)
CPSections[SecIdx].Alignment = Alignment;
CPSections[SecIdx].CPEs.push_back(i);
}
// Now print stuff into the calculated sections.
const MCSection *CurSection = nullptr;
unsigned Offset = 0;
for (unsigned i = 0, e = CPSections.size(); i != e; ++i) {
for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
unsigned CPI = CPSections[i].CPEs[j];
MCSymbol *Sym = GetCPISymbol(CPI);
if (!Sym->isUndefined())
continue;
if (CurSection != CPSections[i].S) {
OutStreamer->switchSection(CPSections[i].S);
emitAlignment(Align(CPSections[i].Alignment));
CurSection = CPSections[i].S;
Offset = 0;
}
MachineConstantPoolEntry CPE = CP[CPI];
// Emit inter-object padding for alignment.
unsigned NewOffset = alignTo(Offset, CPE.getAlign());
OutStreamer->emitZeros(NewOffset - Offset);
Offset = NewOffset + CPE.getSizeInBytes(getDataLayout());
OutStreamer->emitLabel(Sym);
if (CPE.isMachineConstantPoolEntry())
emitMachineConstantPoolValue(CPE.Val.MachineCPVal);
else
emitGlobalConstant(getDataLayout(), CPE.Val.ConstVal);
}
}
}
// Print assembly representations of the jump tables used by the current
// function.
void AsmPrinter::emitJumpTableInfo() {
const DataLayout &DL = MF->getDataLayout();
const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
if (!MJTI) return;
if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty()) return;
// Pick the directive to use to print the jump table entries, and switch to
// the appropriate section.
const Function &F = MF->getFunction();
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
bool JTInDiffSection = !TLOF.shouldPutJumpTableInFunctionSection(
MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32,
F);
if (JTInDiffSection) {
// Drop it in the readonly section.
MCSection *ReadOnlySection = TLOF.getSectionForJumpTable(F, TM);
OutStreamer->switchSection(ReadOnlySection);
}
emitAlignment(Align(MJTI->getEntryAlignment(DL)));
// Jump tables in code sections are marked with a data_region directive
// where that's supported.
if (!JTInDiffSection)
OutStreamer->emitDataRegion(MCDR_DataRegionJT32);
for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
// If this jump table was deleted, ignore it.
if (JTBBs.empty()) continue;
// For the EK_LabelDifference32 entry, if using .set avoids a relocation,
/// emit a .set directive for each unique entry.
if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
MAI->doesSetDirectiveSuppressReloc()) {
SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
for (const MachineBasicBlock *MBB : JTBBs) {
if (!EmittedSets.insert(MBB).second)
continue;
// .set LJTSet, LBB32-base
const MCExpr *LHS =
MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
OutStreamer->emitAssignment(GetJTSetSymbol(JTI, MBB->getNumber()),
MCBinaryExpr::createSub(LHS, Base,
OutContext));
}
}
// On some targets (e.g. Darwin) we want to emit two consecutive labels
// before each jump table. The first label is never referenced, but tells
// the assembler and linker the extents of the jump table object. The
// second label is actually referenced by the code.
if (JTInDiffSection && DL.hasLinkerPrivateGlobalPrefix())
// FIXME: This doesn't have to have any specific name, just any randomly
// named and numbered local label started with 'l' would work. Simplify
// GetJTISymbol.
OutStreamer->emitLabel(GetJTISymbol(JTI, true));
MCSymbol* JTISymbol = GetJTISymbol(JTI);
OutStreamer->emitLabel(JTISymbol);
for (const MachineBasicBlock *MBB : JTBBs)
emitJumpTableEntry(MJTI, MBB, JTI);
}
if (!JTInDiffSection)
OutStreamer->emitDataRegion(MCDR_DataRegionEnd);
}
/// EmitJumpTableEntry - Emit a jump table entry for the specified MBB to the
/// current stream.
void AsmPrinter::emitJumpTableEntry(const MachineJumpTableInfo *MJTI,
const MachineBasicBlock *MBB,
unsigned UID) const {
assert(MBB && MBB->getNumber() >= 0 && "Invalid basic block");
const MCExpr *Value = nullptr;
switch (MJTI->getEntryKind()) {
case MachineJumpTableInfo::EK_Inline:
llvm_unreachable("Cannot emit EK_Inline jump table entry");
case MachineJumpTableInfo::EK_Custom32:
Value = MF->getSubtarget().getTargetLowering()->LowerCustomJumpTableEntry(
MJTI, MBB, UID, OutContext);
break;
case MachineJumpTableInfo::EK_BlockAddress:
// EK_BlockAddress - Each entry is a plain address of block, e.g.:
// .word LBB123
Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
break;
case MachineJumpTableInfo::EK_GPRel32BlockAddress: {
// EK_GPRel32BlockAddress - Each entry is an address of block, encoded
// with a relocation as gp-relative, e.g.:
// .gprel32 LBB123
MCSymbol *MBBSym = MBB->getSymbol();
OutStreamer->emitGPRel32Value(MCSymbolRefExpr::create(MBBSym, OutContext));
return;
}
case MachineJumpTableInfo::EK_GPRel64BlockAddress: {
// EK_GPRel64BlockAddress - Each entry is an address of block, encoded
// with a relocation as gp-relative, e.g.:
// .gpdword LBB123
MCSymbol *MBBSym = MBB->getSymbol();
OutStreamer->emitGPRel64Value(MCSymbolRefExpr::create(MBBSym, OutContext));
return;
}
case MachineJumpTableInfo::EK_LabelDifference32: {
// Each entry is the address of the block minus the address of the jump
// table. This is used for PIC jump tables where gprel32 is not supported.
// e.g.:
// .word LBB123 - LJTI1_2
// If the .set directive avoids relocations, this is emitted as:
// .set L4_5_set_123, LBB123 - LJTI1_2
// .word L4_5_set_123
if (MAI->doesSetDirectiveSuppressReloc()) {
Value = MCSymbolRefExpr::create(GetJTSetSymbol(UID, MBB->getNumber()),
OutContext);
break;
}
Value = MCSymbolRefExpr::create(MBB->getSymbol(), OutContext);
const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF, UID, OutContext);
Value = MCBinaryExpr::createSub(Value, Base, OutContext);
break;
}
}
assert(Value && "Unknown entry kind!");
unsigned EntrySize = MJTI->getEntrySize(getDataLayout());
OutStreamer->emitValue(Value, EntrySize);
}
/// EmitSpecialLLVMGlobal - Check to see if the specified global is a
/// special global used by LLVM. If so, emit it and return true, otherwise
/// do nothing and return false.
bool AsmPrinter::emitSpecialLLVMGlobal(const GlobalVariable *GV) {
if (GV->getName() == "llvm.used") {
if (MAI->hasNoDeadStrip()) // No need to emit this at all.
emitLLVMUsedList(cast<ConstantArray>(GV->getInitializer()));
return true;
}
// Ignore debug and non-emitted data. This handles llvm.compiler.used.
if (GV->getSection() == "llvm.metadata" ||
GV->hasAvailableExternallyLinkage())
return true;
if (!GV->hasAppendingLinkage()) return false;
assert(GV->hasInitializer() && "Not a special LLVM global!");
if (GV->getName() == "llvm.global_ctors") {
emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
/* isCtor */ true);
return true;
}
if (GV->getName() == "llvm.global_dtors") {
emitXXStructorList(GV->getParent()->getDataLayout(), GV->getInitializer(),
/* isCtor */ false);
return true;
}
report_fatal_error("unknown special variable");
}
/// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
/// global in the specified llvm.used list.
void AsmPrinter::emitLLVMUsedList(const ConstantArray *InitList) {
// Should be an array of 'i8*'.
for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
const GlobalValue *GV =
dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
if (GV)
OutStreamer->emitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip);
}
}
void AsmPrinter::preprocessXXStructorList(const DataLayout &DL,
const Constant *List,
SmallVector<Structor, 8> &Structors) {
// Should be an array of '{ i32, void ()*, i8* }' structs. The first value is
// the init priority.
if (!isa<ConstantArray>(List))
return;
// Gather the structors in a form that's convenient for sorting by priority.
for (Value *O : cast<ConstantArray>(List)->operands()) {
auto *CS = cast<ConstantStruct>(O);
if (CS->getOperand(1)->isNullValue())
break; // Found a null terminator, skip the rest.
ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
if (!Priority)
continue; // Malformed.
Structors.push_back(Structor());
Structor &S = Structors.back();
S.Priority = Priority->getLimitedValue(65535);
S.Func = CS->getOperand(1);
if (!CS->getOperand(2)->isNullValue()) {
if (TM.getTargetTriple().isOSAIX())
llvm::report_fatal_error(
"associated data of XXStructor list is not yet supported on AIX");
S.ComdatKey =
dyn_cast<GlobalValue>(CS->getOperand(2)->stripPointerCasts());
}
}
// Emit the function pointers in the target-specific order
llvm::stable_sort(Structors, [](const Structor &L, const Structor &R) {
return L.Priority < R.Priority;
});
}
/// EmitXXStructorList - Emit the ctor or dtor list taking into account the init
/// priority.
void AsmPrinter::emitXXStructorList(const DataLayout &DL, const Constant *List,
bool IsCtor) {
SmallVector<Structor, 8> Structors;
preprocessXXStructorList(DL, List, Structors);
if (Structors.empty())
return;
// Emit the structors in reverse order if we are using the .ctor/.dtor
// initialization scheme.
if (!TM.Options.UseInitArray)
std::reverse(Structors.begin(), Structors.end());
const Align Align = DL.getPointerPrefAlignment();
for (Structor &S : Structors) {
const TargetLoweringObjectFile &Obj = getObjFileLowering();
const MCSymbol *KeySym = nullptr;
if (GlobalValue *GV = S.ComdatKey) {
if (GV->isDeclarationForLinker())
// If the associated variable is not defined in this module
// (it might be available_externally, or have been an
// available_externally definition that was dropped by the
// EliminateAvailableExternally pass), some other TU
// will provide its dynamic initializer.
continue;
KeySym = getSymbol(GV);
}
MCSection *OutputSection =
(IsCtor ? Obj.getStaticCtorSection(S.Priority, KeySym)
: Obj.getStaticDtorSection(S.Priority, KeySym));
OutStreamer->switchSection(OutputSection);
if (OutStreamer->getCurrentSection() != OutStreamer->getPreviousSection())
emitAlignment(Align);
emitXXStructor(DL, S.Func);
}
}
void AsmPrinter::emitModuleIdents(Module &M) {
if (!MAI->hasIdentDirective())
return;
if (const NamedMDNode *NMD = M.getNamedMetadata("llvm.ident")) {
for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
const MDNode *N = NMD->getOperand(i);
assert(N->getNumOperands() == 1 &&
"llvm.ident metadata entry can have only one operand");
const MDString *S = cast<MDString>(N->getOperand(0));
OutStreamer->emitIdent(S->getString());
}
}
}
void AsmPrinter::emitModuleCommandLines(Module &M) {
MCSection *CommandLine = getObjFileLowering().getSectionForCommandLines();
if (!CommandLine)
return;
const NamedMDNode *NMD = M.getNamedMetadata("llvm.commandline");
if (!NMD || !NMD->getNumOperands())
return;
OutStreamer->pushSection();
OutStreamer->switchSection(CommandLine);
OutStreamer->emitZeros(1);
for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
const MDNode *N = NMD->getOperand(i);
assert(N->getNumOperands() == 1 &&
"llvm.commandline metadata entry can have only one operand");
const MDString *S = cast<MDString>(N->getOperand(0));
OutStreamer->emitBytes(S->getString());
OutStreamer->emitZeros(1);
}
OutStreamer->popSection();
}
//===--------------------------------------------------------------------===//
// Emission and print routines
//
/// Emit a byte directive and value.
///
void AsmPrinter::emitInt8(int Value) const { OutStreamer->emitInt8(Value); }
/// Emit a short directive and value.
void AsmPrinter::emitInt16(int Value) const { OutStreamer->emitInt16(Value); }
/// Emit a long directive and value.
void AsmPrinter::emitInt32(int Value) const { OutStreamer->emitInt32(Value); }
/// Emit a long long directive and value.
void AsmPrinter::emitInt64(uint64_t Value) const {
OutStreamer->emitInt64(Value);
}
/// Emit something like ".long Hi-Lo" where the size in bytes of the directive
/// is specified by Size and Hi/Lo specify the labels. This implicitly uses
/// .set if it avoids relocations.
void AsmPrinter::emitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
unsigned Size) const {
OutStreamer->emitAbsoluteSymbolDiff(Hi, Lo, Size);
}
/// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
/// where the size in bytes of the directive is specified by Size and Label
/// specifies the label. This implicitly uses .set if it is available.
void AsmPrinter::emitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
unsigned Size,
bool IsSectionRelative) const {
if (MAI->needsDwarfSectionOffsetDirective() && IsSectionRelative) {
OutStreamer->emitCOFFSecRel32(Label, Offset);
if (Size > 4)
OutStreamer->emitZeros(Size - 4);
return;
}
// Emit Label+Offset (or just Label if Offset is zero)
const MCExpr *Expr = MCSymbolRefExpr::create(Label, OutContext);
if (Offset)
Expr = MCBinaryExpr::createAdd(
Expr, MCConstantExpr::create(Offset, OutContext), OutContext);
OutStreamer->emitValue(Expr, Size);
}
//===----------------------------------------------------------------------===//
// EmitAlignment - Emit an alignment directive to the specified power of
// two boundary. If a global value is specified, and if that global has
// an explicit alignment requested, it will override the alignment request
// if required for correctness.
void AsmPrinter::emitAlignment(Align Alignment, const GlobalObject *GV,
unsigned MaxBytesToEmit) const {
if (GV)
Alignment = getGVAlignment(GV, GV->getParent()->getDataLayout(), Alignment);
if (Alignment == Align(1))
return; // 1-byte aligned: no need to emit alignment.
if (getCurrentSection()->getKind().isText()) {
const MCSubtargetInfo *STI = nullptr;
if (this->MF)
STI = &getSubtargetInfo();
else
STI = TM.getMCSubtargetInfo();
OutStreamer->emitCodeAlignment(Alignment, STI, MaxBytesToEmit);
} else
OutStreamer->emitValueToAlignment(Alignment, 0, 1, MaxBytesToEmit);
}
//===----------------------------------------------------------------------===//
// Constant emission.
//===----------------------------------------------------------------------===//
const MCExpr *AsmPrinter::lowerConstant(const Constant *CV) {
MCContext &Ctx = OutContext;
if (CV->isNullValue() || isa<UndefValue>(CV))
return MCConstantExpr::create(0, Ctx);
if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV))
return MCConstantExpr::create(CI->getZExtValue(), Ctx);
if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
return MCSymbolRefExpr::create(getSymbol(GV), Ctx);
if (const BlockAddress *BA = dyn_cast<BlockAddress>(CV))
return MCSymbolRefExpr::create(GetBlockAddressSymbol(BA), Ctx);
if (const auto *Equiv = dyn_cast<DSOLocalEquivalent>(CV))
return getObjFileLowering().lowerDSOLocalEquivalent(Equiv, TM);
if (const NoCFIValue *NC = dyn_cast<NoCFIValue>(CV))
return MCSymbolRefExpr::create(getSymbol(NC->getGlobalValue()), Ctx);
const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
if (!CE) {
llvm_unreachable("Unknown constant value to lower!");
}
// The constant expression opcodes are limited to those that are necessary
// to represent relocations on supported targets. Expressions involving only
// constant addresses are constant folded instead.
switch (CE->getOpcode()) {
default:
break; // Error
case Instruction::AddrSpaceCast: {
const Constant *Op = CE->getOperand(0);
unsigned DstAS = CE->getType()->getPointerAddressSpace();
unsigned SrcAS = Op->getType()->getPointerAddressSpace();
if (TM.isNoopAddrSpaceCast(SrcAS, DstAS))
return lowerConstant(Op);
break; // Error
}
case Instruction::GetElementPtr: {
// Generate a symbolic expression for the byte address
APInt OffsetAI(getDataLayout().getPointerTypeSizeInBits(CE->getType()), 0);
cast<GEPOperator>(CE)->accumulateConstantOffset(getDataLayout(), OffsetAI);
const MCExpr *Base = lowerConstant(CE->getOperand(0));
if (!OffsetAI)
return Base;
int64_t Offset = OffsetAI.getSExtValue();
return MCBinaryExpr::createAdd(Base, MCConstantExpr::create(Offset, Ctx),
Ctx);
}
case Instruction::Trunc:
// We emit the value and depend on the assembler to truncate the generated
// expression properly. This is important for differences between
// blockaddress labels. Since the two labels are in the same function, it
// is reasonable to treat their delta as a 32-bit value.
[[fallthrough]];
case Instruction::BitCast:
return lowerConstant(CE->getOperand(0));
case Instruction::IntToPtr: {
const DataLayout &DL = getDataLayout();
// Handle casts to pointers by changing them into casts to the appropriate
// integer type. This promotes constant folding and simplifies this code.
Constant *Op = CE->getOperand(0);
Op = ConstantExpr::getIntegerCast(Op, DL.getIntPtrType(CV->getType()),
false/*ZExt*/);
return lowerConstant(Op);
}
case Instruction::PtrToInt: {
const DataLayout &DL = getDataLayout();
// Support only foldable casts to/from pointers that can be eliminated by
// changing the pointer to the appropriately sized integer type.
Constant *Op = CE->getOperand(0);
Type *Ty = CE->getType();
const MCExpr *OpExpr = lowerConstant(Op);
// We can emit the pointer value into this slot if the slot is an
// integer slot equal to the size of the pointer.
//
// If the pointer is larger than the resultant integer, then
// as with Trunc just depend on the assembler to truncate it.
if (DL.getTypeAllocSize(Ty).getFixedValue() <=
DL.getTypeAllocSize(Op->getType()).getFixedValue())
return OpExpr;
break; // Error
}
case Instruction::Sub: {
GlobalValue *LHSGV;
APInt LHSOffset;
DSOLocalEquivalent *DSOEquiv;
if (IsConstantOffsetFromGlobal(CE->getOperand(0), LHSGV, LHSOffset,
getDataLayout(), &DSOEquiv)) {
GlobalValue *RHSGV;
APInt RHSOffset;
if (IsConstantOffsetFromGlobal(CE->getOperand(1), RHSGV, RHSOffset,
getDataLayout())) {
const MCExpr *RelocExpr =
getObjFileLowering().lowerRelativeReference(LHSGV, RHSGV, TM);
if (!RelocExpr) {
const MCExpr *LHSExpr =
MCSymbolRefExpr::create(getSymbol(LHSGV), Ctx);
if (DSOEquiv &&
getObjFileLowering().supportDSOLocalEquivalentLowering())
LHSExpr =
getObjFileLowering().lowerDSOLocalEquivalent(DSOEquiv, TM);
RelocExpr = MCBinaryExpr::createSub(
LHSExpr, MCSymbolRefExpr::create(getSymbol(RHSGV), Ctx), Ctx);
}
int64_t Addend = (LHSOffset - RHSOffset).getSExtValue();
if (Addend != 0)
RelocExpr = MCBinaryExpr::createAdd(
RelocExpr, MCConstantExpr::create(Addend, Ctx), Ctx);
return RelocExpr;
}
}
const MCExpr *LHS = lowerConstant(CE->getOperand(0));
const MCExpr *RHS = lowerConstant(CE->getOperand(1));
return MCBinaryExpr::createSub(LHS, RHS, Ctx);
break;
}
case Instruction::Add: {
const MCExpr *LHS = lowerConstant(CE->getOperand(0));
const MCExpr *RHS = lowerConstant(CE->getOperand(1));
return MCBinaryExpr::createAdd(LHS, RHS, Ctx);
}
}
// If the code isn't optimized, there may be outstanding folding
// opportunities. Attempt to fold the expression using DataLayout as a
// last resort before giving up.
Constant *C = ConstantFoldConstant(CE, getDataLayout());
if (C != CE)
return lowerConstant(C);
// Otherwise report the problem to the user.
std::string S;
raw_string_ostream OS(S);
OS << "Unsupported expression in static initializer: ";
CE->printAsOperand(OS, /*PrintType=*/false,
!MF ? nullptr : MF->getFunction().getParent());
report_fatal_error(Twine(OS.str()));
}
static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *C,
AsmPrinter &AP,
const Constant *BaseCV = nullptr,
uint64_t Offset = 0,
AsmPrinter::AliasMapTy *AliasList = nullptr);
static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP);
static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP);
/// isRepeatedByteSequence - Determine whether the given value is
/// composed of a repeated sequence of identical bytes and return the
/// byte value. If it is not a repeated sequence, return -1.
static int isRepeatedByteSequence(const ConstantDataSequential *V) {
StringRef Data = V->getRawDataValues();
assert(!Data.empty() && "Empty aggregates should be CAZ node");
char C = Data[0];
for (unsigned i = 1, e = Data.size(); i != e; ++i)
if (Data[i] != C) return -1;
return static_cast<uint8_t>(C); // Ensure 255 is not returned as -1.
}
/// isRepeatedByteSequence - Determine whether the given value is
/// composed of a repeated sequence of identical bytes and return the
/// byte value. If it is not a repeated sequence, return -1.
static int isRepeatedByteSequence(const Value *V, const DataLayout &DL) {
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
uint64_t Size = DL.getTypeAllocSizeInBits(V->getType());
assert(Size % 8 == 0);
// Extend the element to take zero padding into account.
APInt Value = CI->getValue().zext(Size);
if (!Value.isSplat(8))
return -1;
return Value.zextOrTrunc(8).getZExtValue();
}
if (const ConstantArray *CA = dyn_cast<ConstantArray>(V)) {
// Make sure all array elements are sequences of the same repeated
// byte.
assert(CA->getNumOperands() != 0 && "Should be a CAZ");
Constant *Op0 = CA->getOperand(0);
int Byte = isRepeatedByteSequence(Op0, DL);
if (Byte == -1)
return -1;
// All array elements must be equal.
for (unsigned i = 1, e = CA->getNumOperands(); i != e; ++i)
if (CA->getOperand(i) != Op0)
return -1;
return Byte;
}
if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(V))
return isRepeatedByteSequence(CDS);
return -1;
}
static void emitGlobalAliasInline(AsmPrinter &AP, uint64_t Offset,
AsmPrinter::AliasMapTy *AliasList) {
if (AliasList) {
auto AliasIt = AliasList->find(Offset);
if (AliasIt != AliasList->end()) {
for (const GlobalAlias *GA : AliasIt->second)
AP.OutStreamer->emitLabel(AP.getSymbol(GA));
AliasList->erase(Offset);
}
}
}
static void emitGlobalConstantDataSequential(
const DataLayout &DL, const ConstantDataSequential *CDS, AsmPrinter &AP,
AsmPrinter::AliasMapTy *AliasList) {
// See if we can aggregate this into a .fill, if so, emit it as such.
int Value = isRepeatedByteSequence(CDS, DL);
if (Value != -1) {
uint64_t Bytes = DL.getTypeAllocSize(CDS->getType());
// Don't emit a 1-byte object as a .fill.
if (Bytes > 1)
return AP.OutStreamer->emitFill(Bytes, Value);
}
// If this can be emitted with .ascii/.asciz, emit it as such.
if (CDS->isString())
return AP.OutStreamer->emitBytes(CDS->getAsString());
// Otherwise, emit the values in successive locations.
unsigned ElementByteSize = CDS->getElementByteSize();
if (isa<IntegerType>(CDS->getElementType())) {
for (unsigned I = 0, E = CDS->getNumElements(); I != E; ++I) {
emitGlobalAliasInline(AP, ElementByteSize * I, AliasList);
if (AP.isVerbose())
AP.OutStreamer->getCommentOS()
<< format("0x%" PRIx64 "\n", CDS->getElementAsInteger(I));
AP.OutStreamer->emitIntValue(CDS->getElementAsInteger(I),
ElementByteSize);
}
} else {
Type *ET = CDS->getElementType();
for (unsigned I = 0, E = CDS->getNumElements(); I != E; ++I) {
emitGlobalAliasInline(AP, ElementByteSize * I, AliasList);
emitGlobalConstantFP(CDS->getElementAsAPFloat(I), ET, AP);
}
}
unsigned Size = DL.getTypeAllocSize(CDS->getType());
unsigned EmittedSize =
DL.getTypeAllocSize(CDS->getElementType()) * CDS->getNumElements();
assert(EmittedSize <= Size && "Size cannot be less than EmittedSize!");
if (unsigned Padding = Size - EmittedSize)
AP.OutStreamer->emitZeros(Padding);
}
static void emitGlobalConstantArray(const DataLayout &DL,
const ConstantArray *CA, AsmPrinter &AP,
const Constant *BaseCV, uint64_t Offset,
AsmPrinter::AliasMapTy *AliasList) {
// See if we can aggregate some values. Make sure it can be
// represented as a series of bytes of the constant value.
int Value = isRepeatedByteSequence(CA, DL);
if (Value != -1) {
uint64_t Bytes = DL.getTypeAllocSize(CA->getType());
AP.OutStreamer->emitFill(Bytes, Value);
} else {
for (unsigned I = 0, E = CA->getNumOperands(); I != E; ++I) {
emitGlobalConstantImpl(DL, CA->getOperand(I), AP, BaseCV, Offset,
AliasList);
Offset += DL.getTypeAllocSize(CA->getOperand(I)->getType());
}
}
}
static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP);
static void emitGlobalConstantVector(const DataLayout &DL,
const ConstantVector *CV, AsmPrinter &AP,
AsmPrinter::AliasMapTy *AliasList) {
Type *ElementType = CV->getType()->getElementType();
uint64_t ElementSizeInBits = DL.getTypeSizeInBits(ElementType);
uint64_t ElementAllocSizeInBits = DL.getTypeAllocSizeInBits(ElementType);
uint64_t EmittedSize;
if (ElementSizeInBits != ElementAllocSizeInBits) {
// If the allocation size of an element is different from the size in bits,
// printing each element separately will insert incorrect padding.
//
// The general algorithm here is complicated; instead of writing it out
// here, just use the existing code in ConstantFolding.
Type *IntT =
IntegerType::get(CV->getContext(), DL.getTypeSizeInBits(CV->getType()));
ConstantInt *CI = dyn_cast_or_null<ConstantInt>(ConstantFoldConstant(
ConstantExpr::getBitCast(const_cast<ConstantVector *>(CV), IntT), DL));
if (!CI) {
report_fatal_error(
"Cannot lower vector global with unusual element type");
}
emitGlobalAliasInline(AP, 0, AliasList);
emitGlobalConstantLargeInt(CI, AP);
EmittedSize = DL.getTypeStoreSize(CV->getType());
} else {
for (unsigned I = 0, E = CV->getType()->getNumElements(); I != E; ++I) {
emitGlobalAliasInline(AP, DL.getTypeAllocSize(CV->getType()) * I, AliasList);
emitGlobalConstantImpl(DL, CV->getOperand(I), AP);
}
EmittedSize =
DL.getTypeAllocSize(ElementType) * CV->getType()->getNumElements();
}
unsigned Size = DL.getTypeAllocSize(CV->getType());
if (unsigned Padding = Size - EmittedSize)
AP.OutStreamer->emitZeros(Padding);
}
static void emitGlobalConstantStruct(const DataLayout &DL,
const ConstantStruct *CS, AsmPrinter &AP,
const Constant *BaseCV, uint64_t Offset,
AsmPrinter::AliasMapTy *AliasList) {
// Print the fields in successive locations. Pad to align if needed!
unsigned Size = DL.getTypeAllocSize(CS->getType());
const StructLayout *Layout = DL.getStructLayout(CS->getType());
uint64_t SizeSoFar = 0;
for (unsigned I = 0, E = CS->getNumOperands(); I != E; ++I) {
const Constant *Field = CS->getOperand(I);
// Print the actual field value.
emitGlobalConstantImpl(DL, Field, AP, BaseCV, Offset + SizeSoFar,
AliasList);
// Check if padding is needed and insert one or more 0s.
uint64_t FieldSize = DL.getTypeAllocSize(Field->getType());
uint64_t PadSize = ((I == E - 1 ? Size : Layout->getElementOffset(I + 1)) -
Layout->getElementOffset(I)) -
FieldSize;
SizeSoFar += FieldSize + PadSize;
// Insert padding - this may include padding to increase the size of the
// current field up to the ABI size (if the struct is not packed) as well
// as padding to ensure that the next field starts at the right offset.
AP.OutStreamer->emitZeros(PadSize);
}
assert(SizeSoFar == Layout->getSizeInBytes() &&
"Layout of constant struct may be incorrect!");
}
static void emitGlobalConstantFP(APFloat APF, Type *ET, AsmPrinter &AP) {
assert(ET && "Unknown float type");
APInt API = APF.bitcastToAPInt();
// First print a comment with what we think the original floating-point value
// should have been.
if (AP.isVerbose()) {
SmallString<8> StrVal;
APF.toString(StrVal);
ET->print(AP.OutStreamer->getCommentOS());
AP.OutStreamer->getCommentOS() << ' ' << StrVal << '\n';
}
// Now iterate through the APInt chunks, emitting them in endian-correct
// order, possibly with a smaller chunk at beginning/end (e.g. for x87 80-bit
// floats).
unsigned NumBytes = API.getBitWidth() / 8;
unsigned TrailingBytes = NumBytes % sizeof(uint64_t);
const uint64_t *p = API.getRawData();
// PPC's long double has odd notions of endianness compared to how LLVM
// handles it: p[0] goes first for *big* endian on PPC.
if (AP.getDataLayout().isBigEndian() && !ET->isPPC_FP128Ty()) {
int Chunk = API.getNumWords() - 1;
if (TrailingBytes)
AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk--], TrailingBytes);
for (; Chunk >= 0; --Chunk)
AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
} else {
unsigned Chunk;
for (Chunk = 0; Chunk < NumBytes / sizeof(uint64_t); ++Chunk)
AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], sizeof(uint64_t));
if (TrailingBytes)
AP.OutStreamer->emitIntValueInHexWithPadding(p[Chunk], TrailingBytes);
}
// Emit the tail padding for the long double.
const DataLayout &DL = AP.getDataLayout();
AP.OutStreamer->emitZeros(DL.getTypeAllocSize(ET) - DL.getTypeStoreSize(ET));
}
static void emitGlobalConstantFP(const ConstantFP *CFP, AsmPrinter &AP) {
emitGlobalConstantFP(CFP->getValueAPF(), CFP->getType(), AP);
}
static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
const DataLayout &DL = AP.getDataLayout();
unsigned BitWidth = CI->getBitWidth();
// Copy the value as we may massage the layout for constants whose bit width
// is not a multiple of 64-bits.
APInt Realigned(CI->getValue());
uint64_t ExtraBits = 0;
unsigned ExtraBitsSize = BitWidth & 63;
if (ExtraBitsSize) {
// The bit width of the data is not a multiple of 64-bits.
// The extra bits are expected to be at the end of the chunk of the memory.
// Little endian:
// * Nothing to be done, just record the extra bits to emit.
// Big endian:
// * Record the extra bits to emit.
// * Realign the raw data to emit the chunks of 64-bits.
if (DL.isBigEndian()) {
// Basically the structure of the raw data is a chunk of 64-bits cells:
// 0 1 BitWidth / 64
// [chunk1][chunk2] ... [chunkN].
// The most significant chunk is chunkN and it should be emitted first.
// However, due to the alignment issue chunkN contains useless bits.
// Realign the chunks so that they contain only useful information:
// ExtraBits 0 1 (BitWidth / 64) - 1
// chu[nk1 chu][nk2 chu] ... [nkN-1 chunkN]
ExtraBitsSize = alignTo(ExtraBitsSize, 8);
ExtraBits = Realigned.getRawData()[0] &
(((uint64_t)-1) >> (64 - ExtraBitsSize));
Realigned.lshrInPlace(ExtraBitsSize);
} else
ExtraBits = Realigned.getRawData()[BitWidth / 64];
}
// We don't expect assemblers to support integer data directives
// for more than 64 bits, so we emit the data in at most 64-bit
// quantities at a time.
const uint64_t *RawData = Realigned.getRawData();
for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
uint64_t Val = DL.isBigEndian() ? RawData[e - i - 1] : RawData[i];
AP.OutStreamer->emitIntValue(Val, 8);
}
if (ExtraBitsSize) {
// Emit the extra bits after the 64-bits chunks.
// Emit a directive that fills the expected size.
uint64_t Size = AP.getDataLayout().getTypeStoreSize(CI->getType());
Size -= (BitWidth / 64) * 8;
assert(Size && Size * 8 >= ExtraBitsSize &&
(ExtraBits & (((uint64_t)-1) >> (64 - ExtraBitsSize)))
== ExtraBits && "Directive too small for extra bits.");
AP.OutStreamer->emitIntValue(ExtraBits, Size);
}
}
/// Transform a not absolute MCExpr containing a reference to a GOT
/// equivalent global, by a target specific GOT pc relative access to the
/// final symbol.
static void handleIndirectSymViaGOTPCRel(AsmPrinter &AP, const MCExpr **ME,
const Constant *BaseCst,
uint64_t Offset) {
// The global @foo below illustrates a global that uses a got equivalent.
//
// @bar = global i32 42
// @gotequiv = private unnamed_addr constant i32* @bar
// @foo = i32 trunc (i64 sub (i64 ptrtoint (i32** @gotequiv to i64),
// i64 ptrtoint (i32* @foo to i64))
// to i32)
//
// The cstexpr in @foo is converted into the MCExpr `ME`, where we actually
// check whether @foo is suitable to use a GOTPCREL. `ME` is usually in the
// form:
//
// foo = cstexpr, where
// cstexpr := <gotequiv> - "." + <cst>
// cstexpr := <gotequiv> - (<foo> - <offset from @foo base>) + <cst>
//
// After canonicalization by evaluateAsRelocatable `ME` turns into:
//
// cstexpr := <gotequiv> - <foo> + gotpcrelcst, where
// gotpcrelcst := <offset from @foo base> + <cst>
MCValue MV;
if (!(*ME)->evaluateAsRelocatable(MV, nullptr, nullptr) || MV.isAbsolute())
return;
const MCSymbolRefExpr *SymA = MV.getSymA();
if (!SymA)
return;
// Check that GOT equivalent symbol is cached.
const MCSymbol *GOTEquivSym = &SymA->getSymbol();
if (!AP.GlobalGOTEquivs.count(GOTEquivSym))
return;
const GlobalValue *BaseGV = dyn_cast_or_null<GlobalValue>(BaseCst);
if (!BaseGV)
return;
// Check for a valid base symbol
const MCSymbol *BaseSym = AP.getSymbol(BaseGV);
const MCSymbolRefExpr *SymB = MV.getSymB();
if (!SymB || BaseSym != &SymB->getSymbol())
return;
// Make sure to match:
//
// gotpcrelcst := <offset from @foo base> + <cst>
//
// If gotpcrelcst is positive it means that we can safely fold the pc rel
// displacement into the GOTPCREL. We can also can have an extra offset <cst>
// if the target knows how to encode it.
int64_t GOTPCRelCst = Offset + MV.getConstant();
if (GOTPCRelCst < 0)
return;
if (!AP.getObjFileLowering().supportGOTPCRelWithOffset() && GOTPCRelCst != 0)
return;
// Emit the GOT PC relative to replace the got equivalent global, i.e.:
//
// bar:
// .long 42
// gotequiv:
// .quad bar
// foo:
// .long gotequiv - "." + <cst>
//
// is replaced by the target specific equivalent to:
//
// bar:
// .long 42
// foo:
// .long bar@GOTPCREL+<gotpcrelcst>
AsmPrinter::GOTEquivUsePair Result = AP.GlobalGOTEquivs[GOTEquivSym];
const GlobalVariable *GV = Result.first;
int NumUses = (int)Result.second;
const GlobalValue *FinalGV = dyn_cast<GlobalValue>(GV->getOperand(0));
const MCSymbol *FinalSym = AP.getSymbol(FinalGV);
*ME = AP.getObjFileLowering().getIndirectSymViaGOTPCRel(
FinalGV, FinalSym, MV, Offset, AP.MMI, *AP.OutStreamer);
// Update GOT equivalent usage information
--NumUses;
if (NumUses >= 0)
AP.GlobalGOTEquivs[GOTEquivSym] = std::make_pair(GV, NumUses);
}
static void emitGlobalConstantImpl(const DataLayout &DL, const Constant *CV,
AsmPrinter &AP, const Constant *BaseCV,
uint64_t Offset,
AsmPrinter::AliasMapTy *AliasList) {
emitGlobalAliasInline(AP, Offset, AliasList);
uint64_t Size = DL.getTypeAllocSize(CV->getType());
// Globals with sub-elements such as combinations of arrays and structs
// are handled recursively by emitGlobalConstantImpl. Keep track of the
// constant symbol base and the current position with BaseCV and Offset.
if (!BaseCV && CV->hasOneUse())
BaseCV = dyn_cast<Constant>(CV->user_back());
if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
return AP.OutStreamer->emitZeros(Size);
if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
const uint64_t StoreSize = DL.getTypeStoreSize(CV->getType());
if (StoreSize <= 8) {
if (AP.isVerbose())
AP.OutStreamer->getCommentOS()
<< format("0x%" PRIx64 "\n", CI->getZExtValue());
AP.OutStreamer->emitIntValue(CI->getZExtValue(), StoreSize);
} else {
emitGlobalConstantLargeInt(CI, AP);
}
// Emit tail padding if needed
if (Size != StoreSize)
AP.OutStreamer->emitZeros(Size - StoreSize);
return;
}
if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV))
return emitGlobalConstantFP(CFP, AP);
if (isa<ConstantPointerNull>(CV)) {
AP.OutStreamer->emitIntValue(0, Size);
return;
}
if (const ConstantDataSequential *CDS = dyn_cast<ConstantDataSequential>(CV))
return emitGlobalConstantDataSequential(DL, CDS, AP, AliasList);
if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV))
return emitGlobalConstantArray(DL, CVA, AP, BaseCV, Offset, AliasList);
if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
return emitGlobalConstantStruct(DL, CVS, AP, BaseCV, Offset, AliasList);
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
// Look through bitcasts, which might not be able to be MCExpr'ized (e.g. of
// vectors).
if (CE->getOpcode() == Instruction::BitCast)
return emitGlobalConstantImpl(DL, CE->getOperand(0), AP);
if (Size > 8) {
// If the constant expression's size is greater than 64-bits, then we have
// to emit the value in chunks. Try to constant fold the value and emit it
// that way.
Constant *New = ConstantFoldConstant(CE, DL);
if (New != CE)
return emitGlobalConstantImpl(DL, New, AP);
}
}
if (const ConstantVector *V = dyn_cast<ConstantVector>(CV))
return emitGlobalConstantVector(DL, V, AP, AliasList);
// Otherwise, it must be a ConstantExpr. Lower it to an MCExpr, then emit it
// thread the streamer with EmitValue.
const MCExpr *ME = AP.lowerConstant(CV);
// Since lowerConstant already folded and got rid of all IR pointer and
// integer casts, detect GOT equivalent accesses by looking into the MCExpr
// directly.
if (AP.getObjFileLowering().supportIndirectSymViaGOTPCRel())
handleIndirectSymViaGOTPCRel(AP, &ME, BaseCV, Offset);
AP.OutStreamer->emitValue(ME, Size);
}
/// EmitGlobalConstant - Print a general LLVM constant to the .s file.
void AsmPrinter::emitGlobalConstant(const DataLayout &DL, const Constant *CV,
AliasMapTy *AliasList) {
uint64_t Size = DL.getTypeAllocSize(CV->getType());
if (Size)
emitGlobalConstantImpl(DL, CV, *this, nullptr, 0, AliasList);
else if (MAI->hasSubsectionsViaSymbols()) {
// If the global has zero size, emit a single byte so that two labels don't
// look like they are at the same location.
OutStreamer->emitIntValue(0, 1);
}
if (!AliasList)
return;
// TODO: These remaining aliases are not emitted in the correct location. Need
// to handle the case where the alias offset doesn't refer to any sub-element.
for (auto &AliasPair : *AliasList) {
for (const GlobalAlias *GA : AliasPair.second)
OutStreamer->emitLabel(getSymbol(GA));
}
}
void AsmPrinter::emitMachineConstantPoolValue(MachineConstantPoolValue *MCPV) {
// Target doesn't support this yet!
llvm_unreachable("Target does not support EmitMachineConstantPoolValue");
}
void AsmPrinter::printOffset(int64_t Offset, raw_ostream &OS) const {
if (Offset > 0)
OS << '+' << Offset;
else if (Offset < 0)
OS << Offset;
}
void AsmPrinter::emitNops(unsigned N) {
MCInst Nop = MF->getSubtarget().getInstrInfo()->getNop();
for (; N; --N)
EmitToStreamer(*OutStreamer, Nop);
}
//===----------------------------------------------------------------------===//
// Symbol Lowering Routines.
//===----------------------------------------------------------------------===//
MCSymbol *AsmPrinter::createTempSymbol(const Twine &Name) const {
return OutContext.createTempSymbol(Name, true);
}
MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BlockAddress *BA) const {
return const_cast<AsmPrinter *>(this)->getAddrLabelSymbol(
BA->getBasicBlock());
}
MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const {
return const_cast<AsmPrinter *>(this)->getAddrLabelSymbol(BB);
}
/// GetCPISymbol - Return the symbol for the specified constant pool entry.
MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
if (getSubtargetInfo().getTargetTriple().isWindowsMSVCEnvironment()) {
const MachineConstantPoolEntry &CPE =
MF->getConstantPool()->getConstants()[CPID];
if (!CPE.isMachineConstantPoolEntry()) {
const DataLayout &DL = MF->getDataLayout();
SectionKind Kind = CPE.getSectionKind(&DL);
const Constant *C = CPE.Val.ConstVal;
Align Alignment = CPE.Alignment;
if (const MCSectionCOFF *S = dyn_cast<MCSectionCOFF>(
getObjFileLowering().getSectionForConstant(DL, Kind, C,
Alignment))) {
if (MCSymbol *Sym = S->getCOMDATSymbol()) {
if (Sym->isUndefined())
OutStreamer->emitSymbolAttribute(Sym, MCSA_Global);
return Sym;
}
}
}
}
const DataLayout &DL = getDataLayout();
return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
"CPI" + Twine(getFunctionNumber()) + "_" +
Twine(CPID));
}
/// GetJTISymbol - Return the symbol for the specified jump table entry.
MCSymbol *AsmPrinter::GetJTISymbol(unsigned JTID, bool isLinkerPrivate) const {
return MF->getJTISymbol(JTID, OutContext, isLinkerPrivate);
}
/// GetJTSetSymbol - Return the symbol for the specified jump table .set
/// FIXME: privatize to AsmPrinter.
MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
const DataLayout &DL = getDataLayout();
return OutContext.getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
Twine(getFunctionNumber()) + "_" +
Twine(UID) + "_set_" + Twine(MBBID));
}
MCSymbol *AsmPrinter::getSymbolWithGlobalValueBase(const GlobalValue *GV,
StringRef Suffix) const {
return getObjFileLowering().getSymbolWithGlobalValueBase(GV, Suffix, TM);
}
/// Return the MCSymbol for the specified ExternalSymbol.
MCSymbol *AsmPrinter::GetExternalSymbolSymbol(StringRef Sym) const {
SmallString<60> NameStr;
Mangler::getNameWithPrefix(NameStr, Sym, getDataLayout());
return OutContext.getOrCreateSymbol(NameStr);
}
/// PrintParentLoopComment - Print comments about parent loops of this one.
static void PrintParentLoopComment(raw_ostream &OS, const MachineLoop *Loop,
unsigned FunctionNumber) {
if (!Loop) return;
PrintParentLoopComment(OS, Loop->getParentLoop(), FunctionNumber);
OS.indent(Loop->getLoopDepth()*2)
<< "Parent Loop BB" << FunctionNumber << "_"
<< Loop->getHeader()->getNumber()
<< " Depth=" << Loop->getLoopDepth() << '\n';
}
/// PrintChildLoopComment - Print comments about child loops within
/// the loop for this basic block, with nesting.
static void PrintChildLoopComment(raw_ostream &OS, const MachineLoop *Loop,
unsigned FunctionNumber) {
// Add child loop information
for (const MachineLoop *CL : *Loop) {
OS.indent(CL->getLoopDepth()*2)
<< "Child Loop BB" << FunctionNumber << "_"
<< CL->getHeader()->getNumber() << " Depth " << CL->getLoopDepth()
<< '\n';
PrintChildLoopComment(OS, CL, FunctionNumber);
}
}
/// emitBasicBlockLoopComments - Pretty-print comments for basic blocks.
static void emitBasicBlockLoopComments(const MachineBasicBlock &MBB,
const MachineLoopInfo *LI,
const AsmPrinter &AP) {
// Add loop depth information
const MachineLoop *Loop = LI->getLoopFor(&MBB);
if (!Loop) return;
MachineBasicBlock *Header = Loop->getHeader();
assert(Header && "No header for loop");
// If this block is not a loop header, just print out what is the loop header
// and return.
if (Header != &MBB) {
AP.OutStreamer->AddComment(" in Loop: Header=BB" +
Twine(AP.getFunctionNumber())+"_" +
Twine(Loop->getHeader()->getNumber())+
" Depth="+Twine(Loop->getLoopDepth()));
return;
}
// Otherwise, it is a loop header. Print out information about child and
// parent loops.
raw_ostream &OS = AP.OutStreamer->getCommentOS();
PrintParentLoopComment(OS, Loop->getParentLoop(), AP.getFunctionNumber());
OS << "=>";
OS.indent(Loop->getLoopDepth()*2-2);
OS << "This ";
if (Loop->isInnermost())
OS << "Inner ";
OS << "Loop Header: Depth=" + Twine(Loop->getLoopDepth()) << '\n';
PrintChildLoopComment(OS, Loop, AP.getFunctionNumber());
}
/// emitBasicBlockStart - This method prints the label for the specified
/// MachineBasicBlock, an alignment (if present) and a comment describing
/// it if appropriate.
void AsmPrinter::emitBasicBlockStart(const MachineBasicBlock &MBB) {
// End the previous funclet and start a new one.
if (MBB.isEHFuncletEntry()) {
for (const HandlerInfo &HI : Handlers) {
HI.Handler->endFunclet();
HI.Handler->beginFunclet(MBB);
}
}
// Switch to a new section if this basic block must begin a section. The
// entry block is always placed in the function section and is handled
// separately.
if (MBB.isBeginSection() && !MBB.isEntryBlock()) {
OutStreamer->switchSection(
getObjFileLowering().getSectionForMachineBasicBlock(MF->getFunction(),
MBB, TM));
CurrentSectionBeginSym = MBB.getSymbol();
}
// Emit an alignment directive for this block, if needed.
const Align Alignment = MBB.getAlignment();
if (Alignment != Align(1))
emitAlignment(Alignment, nullptr, MBB.getMaxBytesForAlignment());
// If the block has its address taken, emit any labels that were used to
// reference the block. It is possible that there is more than one label
// here, because multiple LLVM BB's may have been RAUW'd to this block after
// the references were generated.
if (MBB.isIRBlockAddressTaken()) {
if (isVerbose())
OutStreamer->AddComment("Block address taken");
BasicBlock *BB = MBB.getAddressTakenIRBlock();
assert(BB && BB->hasAddressTaken() && "Missing BB");
for (MCSymbol *Sym : getAddrLabelSymbolToEmit(BB))
OutStreamer->emitLabel(Sym);
} else if (isVerbose() && MBB.isMachineBlockAddressTaken()) {
OutStreamer->AddComment("Block address taken");
}
// Print some verbose block comments.
if (isVerbose()) {
if (const BasicBlock *BB = MBB.getBasicBlock()) {
if (BB->hasName()) {
BB->printAsOperand(OutStreamer->getCommentOS(),
/*PrintType=*/false, BB->getModule());
OutStreamer->getCommentOS() << '\n';
}
}
assert(MLI != nullptr && "MachineLoopInfo should has been computed");
emitBasicBlockLoopComments(MBB, MLI, *this);
}
// Print the main label for the block.
if (shouldEmitLabelForBasicBlock(MBB)) {
if (isVerbose() && MBB.hasLabelMustBeEmitted())
OutStreamer->AddComment("Label of block must be emitted");
OutStreamer->emitLabel(MBB.getSymbol());
} else {
if (isVerbose()) {
// NOTE: Want this comment at start of line, don't emit with AddComment.
OutStreamer->emitRawComment(" %bb." + Twine(MBB.getNumber()) + ":",
false);
}
}
if (MBB.isEHCatchretTarget() &&
MAI->getExceptionHandlingType() == ExceptionHandling::WinEH) {
OutStreamer->emitLabel(MBB.getEHCatchretSymbol());
}
// With BB sections, each basic block must handle CFI information on its own
// if it begins a section (Entry block call is handled separately, next to
// beginFunction).
if (MBB.isBeginSection() && !MBB.isEntryBlock())
for (const HandlerInfo &HI : Handlers)
HI.Handler->beginBasicBlockSection(MBB);
}
void AsmPrinter::emitBasicBlockEnd(const MachineBasicBlock &MBB) {
// Check if CFI information needs to be updated for this MBB with basic block
// sections.
if (MBB.isEndSection())
for (const HandlerInfo &HI : Handlers)
HI.Handler->endBasicBlockSection(MBB);
}
void AsmPrinter::emitVisibility(MCSymbol *Sym, unsigned Visibility,
bool IsDefinition) const {
MCSymbolAttr Attr = MCSA_Invalid;
switch (Visibility) {
default: break;
case GlobalValue::HiddenVisibility:
if (IsDefinition)
Attr = MAI->getHiddenVisibilityAttr();
else
Attr = MAI->getHiddenDeclarationVisibilityAttr();
break;
case GlobalValue::ProtectedVisibility:
Attr = MAI->getProtectedVisibilityAttr();
break;
}
if (Attr != MCSA_Invalid)
OutStreamer->emitSymbolAttribute(Sym, Attr);
}
bool AsmPrinter::shouldEmitLabelForBasicBlock(
const MachineBasicBlock &MBB) const {
// With `-fbasic-block-sections=`, a label is needed for every non-entry block
// in the labels mode (option `=labels`) and every section beginning in the
// sections mode (`=all` and `=list=`).
if ((MF->hasBBLabels() || MBB.isBeginSection()) && !MBB.isEntryBlock())
return true;
// A label is needed for any block with at least one predecessor (when that
// predecessor is not the fallthrough predecessor, or if it is an EH funclet
// entry, or if a label is forced).
return !MBB.pred_empty() &&
(!isBlockOnlyReachableByFallthrough(&MBB) || MBB.isEHFuncletEntry() ||
MBB.hasLabelMustBeEmitted());
}
/// isBlockOnlyReachableByFallthough - Return true if the basic block has
/// exactly one predecessor and the control transfer mechanism between
/// the predecessor and this block is a fall-through.
bool AsmPrinter::
isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
// If this is a landing pad, it isn't a fall through. If it has no preds,
// then nothing falls through to it.
if (MBB->isEHPad() || MBB->pred_empty())
return false;
// If there isn't exactly one predecessor, it can't be a fall through.
if (MBB->pred_size() > 1)
return false;
// The predecessor has to be immediately before this block.
MachineBasicBlock *Pred = *MBB->pred_begin();
if (!Pred->isLayoutSuccessor(MBB))
return false;
// If the block is completely empty, then it definitely does fall through.
if (Pred->empty())
return true;
// Check the terminators in the previous blocks
for (const auto &MI : Pred->terminators()) {
// If it is not a simple branch, we are in a table somewhere.
if (!MI.isBranch() || MI.isIndirectBranch())
return false;
// If we are the operands of one of the branches, this is not a fall
// through. Note that targets with delay slots will usually bundle
// terminators with the delay slot instruction.
for (ConstMIBundleOperands OP(MI); OP.isValid(); ++OP) {
if (OP->isJTI())
return false;
if (OP->isMBB() && OP->getMBB() == MBB)
return false;
}
}
return true;
}
GCMetadataPrinter *AsmPrinter::getOrCreateGCPrinter(GCStrategy &S) {
if (!S.usesMetadata())
return nullptr;
auto [GCPI, Inserted] = GCMetadataPrinters.insert({&S, nullptr});
if (!Inserted)
return GCPI->second.get();
auto Name = S.getName();
for (const GCMetadataPrinterRegistry::entry &GCMetaPrinter :
GCMetadataPrinterRegistry::entries())
if (Name == GCMetaPrinter.getName()) {
std::unique_ptr<GCMetadataPrinter> GMP = GCMetaPrinter.instantiate();
GMP->S = &S;
GCPI->second = std::move(GMP);
return GCPI->second.get();
}
report_fatal_error("no GCMetadataPrinter registered for GC: " + Twine(Name));
}
void AsmPrinter::emitStackMaps() {
GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
assert(MI && "AsmPrinter didn't require GCModuleInfo?");
bool NeedsDefault = false;
if (MI->begin() == MI->end())
// No GC strategy, use the default format.
NeedsDefault = true;
else
for (const auto &I : *MI) {
if (GCMetadataPrinter *MP = getOrCreateGCPrinter(*I))
if (MP->emitStackMaps(SM, *this))
continue;
// The strategy doesn't have printer or doesn't emit custom stack maps.
// Use the default format.
NeedsDefault = true;
}
if (NeedsDefault)
SM.serializeToStackMapSection();
}
/// Pin vtable to this file.
AsmPrinterHandler::~AsmPrinterHandler() = default;
void AsmPrinterHandler::markFunctionEnd() {}
// In the binary's "xray_instr_map" section, an array of these function entries
// describes each instrumentation point. When XRay patches your code, the index
// into this table will be given to your handler as a patch point identifier.
void AsmPrinter::XRayFunctionEntry::emit(int Bytes, MCStreamer *Out) const {
auto Kind8 = static_cast<uint8_t>(Kind);
Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Kind8), 1));
Out->emitBinaryData(
StringRef(reinterpret_cast<const char *>(&AlwaysInstrument), 1));
Out->emitBinaryData(StringRef(reinterpret_cast<const char *>(&Version), 1));
auto Padding = (4 * Bytes) - ((2 * Bytes) + 3);
assert(Padding >= 0 && "Instrumentation map entry > 4 * Word Size");
Out->emitZeros(Padding);
}
void AsmPrinter::emitXRayTable() {
if (Sleds.empty())
return;
auto PrevSection = OutStreamer->getCurrentSectionOnly();
const Function &F = MF->getFunction();
MCSection *InstMap = nullptr;
MCSection *FnSledIndex = nullptr;
const Triple &TT = TM.getTargetTriple();
// Use PC-relative addresses on all targets.
if (TT.isOSBinFormatELF()) {
auto LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
auto Flags = ELF::SHF_ALLOC | ELF::SHF_LINK_ORDER;
StringRef GroupName;
if (F.hasComdat()) {
Flags |= ELF::SHF_GROUP;
GroupName = F.getComdat()->getName();
}
InstMap = OutContext.getELFSection("xray_instr_map", ELF::SHT_PROGBITS,
Flags, 0, GroupName, F.hasComdat(),
MCSection::NonUniqueID, LinkedToSym);
if (!TM.Options.XRayOmitFunctionIndex)
FnSledIndex = OutContext.getELFSection(
"xray_fn_idx", ELF::SHT_PROGBITS, Flags | ELF::SHF_WRITE, 0,
GroupName, F.hasComdat(), MCSection::NonUniqueID, LinkedToSym);
} else if (MF->getSubtarget().getTargetTriple().isOSBinFormatMachO()) {
InstMap = OutContext.getMachOSection("__DATA", "xray_instr_map", 0,
SectionKind::getReadOnlyWithRel());
if (!TM.Options.XRayOmitFunctionIndex)
FnSledIndex = OutContext.getMachOSection(
"__DATA", "xray_fn_idx", 0, SectionKind::getReadOnlyWithRel());
} else {
llvm_unreachable("Unsupported target");
}
auto WordSizeBytes = MAI->getCodePointerSize();
// Now we switch to the instrumentation map section. Because this is done
// per-function, we are able to create an index entry that will represent the
// range of sleds associated with a function.
auto &Ctx = OutContext;
MCSymbol *SledsStart = OutContext.createTempSymbol("xray_sleds_start", true);
OutStreamer->switchSection(InstMap);
OutStreamer->emitLabel(SledsStart);
for (const auto &Sled : Sleds) {
MCSymbol *Dot = Ctx.createTempSymbol();
OutStreamer->emitLabel(Dot);
OutStreamer->emitValueImpl(
MCBinaryExpr::createSub(MCSymbolRefExpr::create(Sled.Sled, Ctx),
MCSymbolRefExpr::create(Dot, Ctx), Ctx),
WordSizeBytes);
OutStreamer->emitValueImpl(
MCBinaryExpr::createSub(
MCSymbolRefExpr::create(CurrentFnBegin, Ctx),
MCBinaryExpr::createAdd(MCSymbolRefExpr::create(Dot, Ctx),
MCConstantExpr::create(WordSizeBytes, Ctx),
Ctx),
Ctx),
WordSizeBytes);
Sled.emit(WordSizeBytes, OutStreamer.get());
}
MCSymbol *SledsEnd = OutContext.createTempSymbol("xray_sleds_end", true);
OutStreamer->emitLabel(SledsEnd);
// We then emit a single entry in the index per function. We use the symbols
// that bound the instrumentation map as the range for a specific function.
// Each entry here will be 2 * word size aligned, as we're writing down two
// pointers. This should work for both 32-bit and 64-bit platforms.
if (FnSledIndex) {
OutStreamer->switchSection(FnSledIndex);
OutStreamer->emitCodeAlignment(Align(2 * WordSizeBytes),
&getSubtargetInfo());
OutStreamer->emitSymbolValue(SledsStart, WordSizeBytes, false);
OutStreamer->emitSymbolValue(SledsEnd, WordSizeBytes, false);
OutStreamer->switchSection(PrevSection);
}
Sleds.clear();
}
void AsmPrinter::recordSled(MCSymbol *Sled, const MachineInstr &MI,
SledKind Kind, uint8_t Version) {
const Function &F = MI.getMF()->getFunction();
auto Attr = F.getFnAttribute("function-instrument");
bool LogArgs = F.hasFnAttribute("xray-log-args");
bool AlwaysInstrument =
Attr.isStringAttribute() && Attr.getValueAsString() == "xray-always";
if (Kind == SledKind::FUNCTION_ENTER && LogArgs)
Kind = SledKind::LOG_ARGS_ENTER;
Sleds.emplace_back(XRayFunctionEntry{Sled, CurrentFnSym, Kind,
AlwaysInstrument, &F, Version});
}
void AsmPrinter::emitPatchableFunctionEntries() {
const Function &F = MF->getFunction();
unsigned PatchableFunctionPrefix = 0, PatchableFunctionEntry = 0;
(void)F.getFnAttribute("patchable-function-prefix")
.getValueAsString()
.getAsInteger(10, PatchableFunctionPrefix);
(void)F.getFnAttribute("patchable-function-entry")
.getValueAsString()
.getAsInteger(10, PatchableFunctionEntry);
if (!PatchableFunctionPrefix && !PatchableFunctionEntry)
return;
const unsigned PointerSize = getPointerSize();
if (TM.getTargetTriple().isOSBinFormatELF()) {
auto Flags = ELF::SHF_WRITE | ELF::SHF_ALLOC;
const MCSymbolELF *LinkedToSym = nullptr;
StringRef GroupName;
// GNU as < 2.35 did not support section flag 'o'. GNU ld < 2.36 did not
// support mixed SHF_LINK_ORDER and non-SHF_LINK_ORDER sections.
if (MAI->useIntegratedAssembler() || MAI->binutilsIsAtLeast(2, 36)) {
Flags |= ELF::SHF_LINK_ORDER;
if (F.hasComdat()) {
Flags |= ELF::SHF_GROUP;
GroupName = F.getComdat()->getName();
}
LinkedToSym = cast<MCSymbolELF>(CurrentFnSym);
}
OutStreamer->switchSection(OutContext.getELFSection(
"__patchable_function_entries", ELF::SHT_PROGBITS, Flags, 0, GroupName,
F.hasComdat(), MCSection::NonUniqueID, LinkedToSym));
emitAlignment(Align(PointerSize));
OutStreamer->emitSymbolValue(CurrentPatchableFunctionEntrySym, PointerSize);
}
}
uint16_t AsmPrinter::getDwarfVersion() const {
return OutStreamer->getContext().getDwarfVersion();
}
void AsmPrinter::setDwarfVersion(uint16_t Version) {
OutStreamer->getContext().setDwarfVersion(Version);
}
bool AsmPrinter::isDwarf64() const {
return OutStreamer->getContext().getDwarfFormat() == dwarf::DWARF64;
}
unsigned int AsmPrinter::getDwarfOffsetByteSize() const {
return dwarf::getDwarfOffsetByteSize(
OutStreamer->getContext().getDwarfFormat());
}
dwarf::FormParams AsmPrinter::getDwarfFormParams() const {
return {getDwarfVersion(), uint8_t(getPointerSize()),
OutStreamer->getContext().getDwarfFormat(),
doesDwarfUseRelocationsAcrossSections()};
}
unsigned int AsmPrinter::getUnitLengthFieldByteSize() const {
return dwarf::getUnitLengthFieldByteSize(
OutStreamer->getContext().getDwarfFormat());
}