//===- 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/StringExtras.h" #include "llvm/ADT/StringRef.h" #include "llvm/ADT/TinyPtrVector.h" #include "llvm/ADT/Twine.h" #include "llvm/Analysis/ConstantFolding.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/LazyMachineBlockFrequencyInfo.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/EHPersonalities.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/Object/ELFTypes.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 "llvm/TargetParser/Triple.h" #include #include #include #include #include #include #include #include #include #include using namespace llvm; #define DEBUG_TYPE "asm-printer" static cl::opt BasicBlockProfileDump( "mbb-profile-dump", cl::Hidden, cl::desc("Basic block profile dump for external cost modelling. If " "matching up BBs with afterwards, the compilation must be " "performed with -basic-block-sections=labels. Enabling this " "flag during in-process ThinLTO is not supported.")); 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 Symbols; Function *Fn; // The containing function of the BasicBlock. unsigned Index; // The index in BBCallbacks for the BasicBlock. }; DenseMap, 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 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, std::vector> DeletedAddrLabelsNeedingEmission; public: AddrLabelMap(MCContext &context) : Context(context) {} ~AddrLabelMap() { assert(DeletedAddrLabelsNeedingEmission.empty() && "Some labels for deleted blocks never got emitted"); } ArrayRef getAddrLabelSymbolToEmit(BasicBlock *BB); void takeDeletedSymbolsForFunction(Function *F, std::vector &Result); void UpdateForDeletedBlock(BasicBlock *BB); void UpdateForRAUWBlock(BasicBlock *Old, BasicBlock *New); }; ArrayRef 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 &Result) { DenseMap, std::vector>::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 AsmPrinter::getAddrLabelSymbolToEmit(const BasicBlock *BB) { // Lazily create AddrLabelSymbols. if (!AddrLabelSymbols) AddrLabelSymbols = std::make_unique(OutContext); return AddrLabelSymbols->getAddrLabelSymbolToEmit( const_cast(BB)); } void AsmPrinter::takeDeletedSymbolsForFunction( const Function *F, std::vector &Result) { // If no blocks have had their addresses taken, we're done. if (!AddrLabelSymbols) return; return AddrLabelSymbols->takeDeletedSymbolsForFunction( const_cast(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(getValPtr())); } void AddrLabelMapCallbackPtr::allUsesReplacedWith(Value *V2) { Map->UpdateForRAUWBlock(cast(getValPtr()), cast(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(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 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(); } 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(); AU.addRequired(); AU.addRequired(); } bool AsmPrinter::doInitialization(Module &M) { auto *MMIWP = getAnalysisIfAvailable(); MMI = MMIWP ? &MMIWP->getMMI() : nullptr; HasSplitStack = false; HasNoSplitStack = false; AddrLabelSymbols = nullptr; // Initialize TargetLoweringObjectFile. const_cast(getObjFileLowering()) .Initialize(OutContext, TM); const_cast(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); } } // On AIX, emit bytes for llvm.commandline metadata after .file so that the // C_INFO symbol is preserved if any csect is kept by the linker. if (TM.getTargetTriple().isOSBinFormatXCOFF()) emitModuleCommandLines(M); GCModuleInfo *MI = getAnalysisIfAvailable(); 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(this), DbgTimerName, DbgTimerDescription, CodeViewLineTablesGroupName, CodeViewLineTablesGroupDescription); } if (!EmitCodeView || M.getDwarfVersion()) { if (MMI->hasDebugInfo()) { DD = new DwarfDebug(this); Handlers.emplace_back(std::unique_ptr(DD), DbgTimerName, DbgTimerDescription, DWARFGroupName, DWARFGroupDescription); } } } if (M.getNamedMetadata(PseudoProbeDescMetadataName)) { PP = new PseudoProbeHandler(this); Handlers.emplace_back(std::unique_ptr(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 || usesCFIWithoutEH() || ModuleCFISection != CFISection::EH); break; default: break; } EHStreamer *ES = nullptr; switch (MAI->getExceptionHandlingType()) { case ExceptionHandling::None: if (!usesCFIWithoutEH()) 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(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(M.getModuleFlag("cfguard"))) Handlers.emplace_back(std::make_unique(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); } if (!BasicBlockProfileDump.empty()) { std::error_code PossibleFileError; MBBProfileDumpFileOutput = std::make_unique( BasicBlockProfileDump, PossibleFileError); if (PossibleFileError) { M.getContext().emitError("Failed to open file for MBB Profile Dump: " + PossibleFileError.message() + "\n"); } } 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 &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); // 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 prologue data for the indirect call sanitizer. if (const MDNode *MD = F.getMetadata(LLVMContext::MD_func_sanitize)) { assert(MD->getNumOperands() == 2); auto *PrologueSig = mdconst::extract(MD->getOperand(0)); auto *TypeHash = mdconst::extract(MD->getOperand(1)); emitGlobalConstant(F.getParent()->getDataLayout(), PrologueSig); emitGlobalConstant(F.getParent()->getDataLayout(), TypeHash); } if (isVerbose()) { F.printAsOperand(OutStreamer->getCommentOS(), /*PrintType=*/false, F.getParent()); emitFunctionHeaderComment(); OutStreamer->getCommentOS() << '\n'; } // 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 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()); } /// 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(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 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(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 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( 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 (MAI->usesCFIWithoutEH() && F.hasUWTable()) return CFISection::EH; assert(MMI != nullptr && "Invalid machine module info"); 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::usesCFIWithoutEH() const { return MAI->usesCFIWithoutEH() && ModuleCFISection != CFISection::None; } void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) { ExceptionHandling ExceptionHandlingType = MAI->getExceptionHandlingType(); if (!usesCFIWithoutEH() && 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 &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 SHT_LLVM_BB_ADDR_MAP section /// for a given basic block. This can be used to capture more precise profile /// information. static uint32_t getBBAddrMapMetadata(const MachineBasicBlock &MBB) { const TargetInstrInfo *TII = MBB.getParent()->getSubtarget().getInstrInfo(); return object::BBAddrMap::BBEntry::Metadata{ MBB.isReturnBlock(), !MBB.empty() && TII->isTailCall(MBB.back()), MBB.isEHPad(), const_cast(MBB).canFallThrough(), !MBB.empty() && MBB.rbegin()->isIndirectBranch()} .encode(); } 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 function. 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(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(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 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(MD.getOperand(0)) && "first operand not a string"); bool ConstULEB128 = false; for (const MDOperand &MDO : MD.operands()) { if (auto *S = dyn_cast(MDO)) { // Found string, start of new section! // Find options for this section "
!" - supported options: // C = Compress constant integers of size 2-8 bytes as ULEB128. const StringRef SecWithOpt = S->getString(); const size_t OptStart = SecWithOpt.find('!'); // likely npos const StringRef Sec = SecWithOpt.substr(0, OptStart); const StringRef Opts = SecWithOpt.substr(OptStart); // likely empty ConstULEB128 = Opts.find('C') != StringRef::npos; #ifndef NDEBUG for (char O : Opts) assert((O == '!' || O == 'C') && "Invalid !pcsections options"); #endif SwitchSection(Sec); 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 { // Emit delta between symbol and previous symbol. if (ConstULEB128) emitLabelDifferenceAsULEB128(Sym, Prev); else emitLabelDifference(Sym, Prev, 4); } Prev = Sym; } } else { // Emit auxiliary data after PC. assert(isa(MDO) && "expecting either string or tuple"); const auto *AuxMDs = cast(MDO); for (const MDOperand &AuxMDO : AuxMDs->operands()) { assert(isa(AuxMDO) && "expecting a constant"); const Constant *C = cast(AuxMDO)->getValue(); const DataLayout &DL = F.getParent()->getDataLayout(); const uint64_t Size = DL.getTypeStoreSize(C->getType()); if (auto *CI = dyn_cast(C); CI && ConstULEB128 && Size > 1 && Size <= 8) { emitULEB128(CI->getZExtValue()); } else { emitGlobalConstant(DL, C); } } } } }; 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(); if (!MDT) { OwnedMDT = std::make_unique(); OwnedMDT->getBase().recalculate(*MF); MDT = OwnedMDT.get(); } // Get MachineLoopInfo or compute it on the fly if it's unavailable MLI = getAnalysisIfAvailable(); if (!MLI) { OwnedMLI = std::make_unique(); OwnedMLI->getBase().analyze(MDT->getBase()); MLI = OwnedMLI.get(); } } // Print out code for the function. bool HasAnyRealCode = false; int NumInstsInFunction = 0; bool IsEHa = MMI->getModule()->getModuleFlag("eh-asynch"); bool CanDoExtraAnalysis = ORE->allowExtraAnalysis(DEBUG_TYPE); for (auto &MBB : *MF) { // Print a label for the basic block. emitBasicBlockStart(MBB); DenseMap 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::GC_LABEL: OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol()); break; case TargetOpcode::EH_LABEL: OutStreamer->emitLabel(MI.getOperand(0).getMCSymbol()); // For AsynchEH, insert a Nop if followed by a trap inst // Or the exception won't be caught. // (see MCConstantExpr::create(1,..) in WinException.cpp) // Ignore SDiv/UDiv because a DIV with Const-0 divisor // must have being turned into an UndefValue. // Div with variable opnds won't be the first instruction in // an EH region as it must be led by at least a Load { auto MI2 = std::next(MI.getIterator()); if (IsEHa && MI2 != MBB.end() && (MI2->mayLoadOrStore() || MI2->mayRaiseFPException())) emitNops(1); } 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, 128> MnemonicVec; for (auto &KV : MnemonicCounts) MnemonicVec.emplace_back(KV.first, KV.second); sort(MnemonicVec, [](const std::pair &A, const std::pair &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(); // Output MBB ids, function names, and frequencies if the flag to dump // MBB profile information has been set if (MBBProfileDumpFileOutput) { if (!MF->hasBBLabels()) MF->getContext().reportError( SMLoc(), "Unable to find BB labels for MBB profile dump. -mbb-profile-dump " "must be called with -basic-block-sections=labels"); MachineBlockFrequencyInfo &MBFI = getAnalysis().getBFI(); for (const auto &MBB : *MF) { *MBBProfileDumpFileOutput.get() << MF->getName() << "," << MBB.getBBID() << "," << MBFI.getBlockFreqRelativeToEntryBlock(&MBB) << "\n"; } } } /// Compute the number of Global Variables that uses a Constant. static unsigned getNumGlobalVariableUses(const Constant *C) { if (!C) return 0; if (isa(C)) return 1; unsigned NumUses = 0; for (const auto *CU : C->users()) NumUses += getNumGlobalVariableUses(dyn_cast(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(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(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 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(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(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(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> Filename; if (std::optional 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 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(); // 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(); // 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 AliasStack; SmallPtrSet AliasVisited; for (const auto &Alias : M.aliases()) { if (Alias.hasAvailableExternallyLinkage()) continue; for (const GlobalAlias *Cur = &Alias; Cur; Cur = dyn_cast(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(); 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. // The command line metadata is emitted earlier on XCOFF. if (!TM.getTargetTriple().isOSBinFormatXCOFF()) 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().getORE(); } namespace { // Keep track the alignment, constpool entries per Section. struct SectionCPs { MCSection *S; Align Alignment; SmallVector 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 &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 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 &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 &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 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(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(InitList->getOperand(i)->stripPointerCasts()); if (GV) OutStreamer->emitSymbolAttribute(getSymbol(GV), MCSA_NoDeadStrip); } } void AsmPrinter::preprocessXXStructorList(const DataLayout &DL, const Constant *List, SmallVector &Structors) { // Should be an array of '{ i32, void ()*, i8* }' structs. The first value is // the init priority. if (!isa(List)) return; // Gather the structors in a form that's convenient for sorting by priority. for (Value *O : cast(List)->operands()) { auto *CS = cast(O); if (CS->getOperand(1)->isNullValue()) break; // Found a null terminator, skip the rest. ConstantInt *Priority = dyn_cast(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(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 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(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(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); } /// EmitSLEB128 - emit the specified signed leb128 value. void AsmPrinter::emitSLEB128(int64_t Value, const char *Desc) const { if (isVerbose() && Desc) OutStreamer->AddComment(Desc); OutStreamer->emitSLEB128IntValue(Value); } void AsmPrinter::emitULEB128(uint64_t Value, const char *Desc, unsigned PadTo) const { if (isVerbose() && Desc) OutStreamer->AddComment(Desc); OutStreamer->emitULEB128IntValue(Value, PadTo); } /// 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); } /// Emit something like ".uleb128 Hi-Lo". void AsmPrinter::emitLabelDifferenceAsULEB128(const MCSymbol *Hi, const MCSymbol *Lo) const { OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo); } /// 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(CV)) return MCConstantExpr::create(0, Ctx); if (const ConstantInt *CI = dyn_cast(CV)) return MCConstantExpr::create(CI->getZExtValue(), Ctx); if (const GlobalValue *GV = dyn_cast(CV)) return MCSymbolRefExpr::create(getSymbol(GV), Ctx); if (const BlockAddress *BA = dyn_cast(CV)) return MCSymbolRefExpr::create(GetBlockAddressSymbol(BA), Ctx); if (const auto *Equiv = dyn_cast(CV)) return getObjFileLowering().lowerDSOLocalEquivalent(Equiv, TM); if (const NoCFIValue *NC = dyn_cast(CV)) return MCSymbolRefExpr::create(getSymbol(NC->getGlobalValue()), Ctx); const ConstantExpr *CE = dyn_cast(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(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(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(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(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(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(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(ConstantFoldConstant( ConstantExpr::getBitCast(const_cast(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)); if (BitWidth >= 64) 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 := - "." + // cstexpr := - ( - ) + // // After canonicalization by evaluateAsRelocatable `ME` turns into: // // cstexpr := - + gotpcrelcst, where // gotpcrelcst := + 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(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 := + // // 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 // 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 - "." + // // is replaced by the target specific equivalent to: // // bar: // .long 42 // foo: // .long bar@GOTPCREL+ AsmPrinter::GOTEquivUsePair Result = AP.GlobalGOTEquivs[GOTEquivSym]; const GlobalVariable *GV = Result.first; int NumUses = (int)Result.second; const GlobalValue *FinalGV = dyn_cast(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(CV->user_back()); if (isa(CV) || isa(CV)) return AP.OutStreamer->emitZeros(Size); if (const ConstantInt *CI = dyn_cast(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(CV)) return emitGlobalConstantFP(CFP, AP); if (isa(CV)) { AP.OutStreamer->emitIntValue(0, Size); return; } if (const ConstantDataSequential *CDS = dyn_cast(CV)) return emitGlobalConstantDataSequential(DL, CDS, AP, AliasList); if (const ConstantArray *CVA = dyn_cast(CV)) return emitGlobalConstantArray(DL, CVA, AP, BaseCV, Offset, AliasList); if (const ConstantStruct *CVS = dyn_cast(CV)) return emitGlobalConstantStruct(DL, CVS, AP, BaseCV, Offset, AliasList); if (const ConstantExpr *CE = dyn_cast(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(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(this)->getAddrLabelSymbol( BA->getBasicBlock()); } MCSymbol *AsmPrinter::GetBlockAddressSymbol(const BasicBlock *BB) const { return const_cast(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( 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 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(); 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(Kind); Out->emitBinaryData(StringRef(reinterpret_cast(&Kind8), 1)); Out->emitBinaryData( StringRef(reinterpret_cast(&AlwaysInstrument), 1)); Out->emitBinaryData(StringRef(reinterpret_cast(&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(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.XRayFunctionIndex) FnSledIndex = OutContext.getELFSection( "xray_fn_idx", ELF::SHT_PROGBITS, Flags, 0, GroupName, F.hasComdat(), MCSection::NonUniqueID, LinkedToSym); } else if (MF->getSubtarget().getTargetTriple().isOSBinFormatMachO()) { InstMap = OutContext.getMachOSection("__DATA", "xray_instr_map", MachO::S_ATTR_LIVE_SUPPORT, SectionKind::getReadOnlyWithRel()); if (TM.Options.XRayFunctionIndex) FnSledIndex = OutContext.getMachOSection("__DATA", "xray_fn_idx", MachO::S_ATTR_LIVE_SUPPORT, SectionKind::getReadOnly()); } 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.createLinkerPrivateSymbol("xray_sleds_start"); 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()); // For Mach-O, use an "l" symbol as the atom of this subsection. The label // difference uses a SUBTRACTOR external relocation which references the // symbol. MCSymbol *Dot = Ctx.createLinkerPrivateSymbol("xray_fn_idx"); OutStreamer->emitLabel(Dot); OutStreamer->emitValueImpl( MCBinaryExpr::createSub(MCSymbolRefExpr::create(SledsStart, Ctx), MCSymbolRefExpr::create(Dot, Ctx), Ctx), WordSizeBytes); OutStreamer->emitValueImpl(MCConstantExpr::create(Sleds.size(), Ctx), WordSizeBytes); 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(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(MAI->getCodePointerSize()), OutStreamer->getContext().getDwarfFormat(), doesDwarfUseRelocationsAcrossSections()}; } unsigned int AsmPrinter::getUnitLengthFieldByteSize() const { return dwarf::getUnitLengthFieldByteSize( OutStreamer->getContext().getDwarfFormat()); }