LLVMTargetMachine.cpp

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//===-- LLVMTargetMachine.cpp - Implement the LLVMTargetMachine class -----===//
//
// 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 LLVMTargetMachine class.
//
//===----------------------------------------------------------------------===//
 
#include "llvm/Analysis/Passes.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
 
static cl::opt<bool>
    EnableTrapUnreachable("trap-unreachable", cl::Hidden,
                          cl::desc("Enable generating trap for unreachable"));
 
static cl::opt<bool> EnableNoTrapAfterNoreturn(
    "no-trap-after-noreturn", cl::Hidden,
    cl::desc("Do not emit a trap instruction for 'unreachable' IR instructions "
             "after noreturn calls, even if --trap-unreachable is set."));
 
void LLVMTargetMachine::initAsmInfo() {
  MRI.reset(TheTarget.createMCRegInfo(getTargetTriple().str()));
  assert(MRI && "Unable to create reg info");
  MII.reset(TheTarget.createMCInstrInfo());
  assert(MII && "Unable to create instruction info");
  // FIXME: Having an MCSubtargetInfo on the target machine is a hack due
  // to some backends having subtarget feature dependent module level
  // code generation. This is similar to the hack in the AsmPrinter for
  // module level assembly etc.
  STI.reset(TheTarget.createMCSubtargetInfo(
      getTargetTriple().str(), getTargetCPU(), getTargetFeatureString()));
  assert(STI && "Unable to create subtarget info");
 
  MCAsmInfo *TmpAsmInfo = TheTarget.createMCAsmInfo(
      *MRI, getTargetTriple().str(), Options.MCOptions);
  // TargetSelect.h moved to a different directory between LLVM 2.9 and 3.0,
  // and if the old one gets included then MCAsmInfo will be NULL and
  // we'll crash later.
  // Provide the user with a useful error message about what's wrong.
  assert(TmpAsmInfo && "MCAsmInfo not initialized. "
         "Make sure you include the correct TargetSelect.h"
         "and that InitializeAllTargetMCs() is being invoked!");
 
  if (Options.BinutilsVersion.first > 0)
    TmpAsmInfo->setBinutilsVersion(Options.BinutilsVersion);
 
  if (Options.DisableIntegratedAS) {
    TmpAsmInfo->setUseIntegratedAssembler(false);
    // If there is explict option disable integratedAS, we can't use it for
    // inlineasm either.
    TmpAsmInfo->setParseInlineAsmUsingAsmParser(false);
  }
 
  TmpAsmInfo->setPreserveAsmComments(Options.MCOptions.PreserveAsmComments);
 
  TmpAsmInfo->setCompressDebugSections(Options.CompressDebugSections);
 
  TmpAsmInfo->setRelaxELFRelocations(Options.RelaxELFRelocations);
 
  if (Options.ExceptionModel != ExceptionHandling::None)
    TmpAsmInfo->setExceptionsType(Options.ExceptionModel);
 
  AsmInfo.reset(TmpAsmInfo);
}
 
LLVMTargetMachine::LLVMTargetMachine(const Target &T,
                                     StringRef DataLayoutString,
                                     const Triple &TT, StringRef CPU,
                                     StringRef FS, const TargetOptions &Options,
                                     Reloc::Model RM, CodeModel::Model CM,
                                     CodeGenOptLevel OL)
    : TargetMachine(T, DataLayoutString, TT, CPU, FS, Options) {
  this->RM = RM;
  this->CMModel = CM;
  this->OptLevel = OL;
 
  if (EnableTrapUnreachable)
    this->Options.TrapUnreachable = true;
  if (EnableNoTrapAfterNoreturn)
    this->Options.NoTrapAfterNoreturn = true;
}
 
TargetTransformInfo
LLVMTargetMachine::getTargetTransformInfo(const Function &F) const {
  return TargetTransformInfo(BasicTTIImpl(this, F));
}
 
/// addPassesToX helper drives creation and initialization of TargetPassConfig.
static TargetPassConfig *
addPassesToGenerateCode(LLVMTargetMachine &TM, PassManagerBase &PM,
                        bool DisableVerify,
                        MachineModuleInfoWrapperPass &MMIWP) {
  // Targets may override createPassConfig to provide a target-specific
  // subclass.
  TargetPassConfig *PassConfig = TM.createPassConfig(PM);
  // Set PassConfig options provided by TargetMachine.
  PassConfig->setDisableVerify(DisableVerify);
  PM.add(PassConfig);
  PM.add(&MMIWP);
 
  if (PassConfig->addISelPasses())
    return nullptr;
  PassConfig->addMachinePasses();
  PassConfig->setInitialized();
  return PassConfig;
}
 
bool LLVMTargetMachine::addAsmPrinter(PassManagerBase &PM,
                                      raw_pwrite_stream &Out,
                                      raw_pwrite_stream *DwoOut,
                                      CodeGenFileType FileType,
                                      MCContext &Context) {
  Expected<std::unique_ptr<MCStreamer>> MCStreamerOrErr =
      createMCStreamer(Out, DwoOut, FileType, Context);
  if (auto Err = MCStreamerOrErr.takeError())
    return true;
 
  // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
  FunctionPass *Printer =
      getTarget().createAsmPrinter(*this, std::move(*MCStreamerOrErr));
  if (!Printer)
    return true;
 
  PM.add(Printer);
  return false;
}
 
Expected<std::unique_ptr<MCStreamer>> LLVMTargetMachine::createMCStreamer(
    raw_pwrite_stream &Out, raw_pwrite_stream *DwoOut, CodeGenFileType FileType,
    MCContext &Context) {
  if (Options.MCOptions.MCSaveTempLabels)
    Context.setAllowTemporaryLabels(false);
 
  const MCSubtargetInfo &STI = *getMCSubtargetInfo();
  const MCAsmInfo &MAI = *getMCAsmInfo();
  const MCRegisterInfo &MRI = *getMCRegisterInfo();
  const MCInstrInfo &MII = *getMCInstrInfo();
 
  std::unique_ptr<MCStreamer> AsmStreamer;
 
  switch (FileType) {
  case CodeGenFileType::AssemblyFile: {
    MCInstPrinter *InstPrinter = getTarget().createMCInstPrinter(
        getTargetTriple(), MAI.getAssemblerDialect(), MAI, MII, MRI);
 
    // Create a code emitter if asked to show the encoding.
    std::unique_ptr<MCCodeEmitter> MCE;
    if (Options.MCOptions.ShowMCEncoding)
      MCE.reset(getTarget().createMCCodeEmitter(MII, Context));
 
    bool UseDwarfDirectory = false;
    switch (Options.MCOptions.MCUseDwarfDirectory) {
    case MCTargetOptions::DisableDwarfDirectory:
      UseDwarfDirectory = false;
      break;
    case MCTargetOptions::EnableDwarfDirectory:
      UseDwarfDirectory = true;
      break;
    case MCTargetOptions::DefaultDwarfDirectory:
      UseDwarfDirectory = MAI.enableDwarfFileDirectoryDefault();
      break;
    }
 
    std::unique_ptr<MCAsmBackend> MAB(
        getTarget().createMCAsmBackend(STI, MRI, Options.MCOptions));
    auto FOut = std::make_unique<formatted_raw_ostream>(Out);
    MCStreamer *S = getTarget().createAsmStreamer(
        Context, std::move(FOut), Options.MCOptions.AsmVerbose,
        UseDwarfDirectory, InstPrinter, std::move(MCE), std::move(MAB),
        Options.MCOptions.ShowMCInst);
    AsmStreamer.reset(S);
    break;
  }
  case CodeGenFileType::ObjectFile: {
    // Create the code emitter for the target if it exists.  If not, .o file
    // emission fails.
    MCCodeEmitter *MCE = getTarget().createMCCodeEmitter(MII, Context);
    if (!MCE)
      return make_error<StringError>("createMCCodeEmitter failed",
                                     inconvertibleErrorCode());
    MCAsmBackend *MAB =
        getTarget().createMCAsmBackend(STI, MRI, Options.MCOptions);
    if (!MAB)
      return make_error<StringError>("createMCAsmBackend failed",
                                     inconvertibleErrorCode());
 
    Triple T(getTargetTriple().str());
    AsmStreamer.reset(getTarget().createMCObjectStreamer(
        T, Context, std::unique_ptr<MCAsmBackend>(MAB),
        DwoOut ? MAB->createDwoObjectWriter(Out, *DwoOut)
               : MAB->createObjectWriter(Out),
        std::unique_ptr<MCCodeEmitter>(MCE), STI, Options.MCOptions.MCRelaxAll,
        Options.MCOptions.MCIncrementalLinkerCompatible,
        /*DWARFMustBeAtTheEnd*/ true));
    break;
  }
  case CodeGenFileType::Null:
    // The Null output is intended for use for performance analysis and testing,
    // not real users.
    AsmStreamer.reset(getTarget().createNullStreamer(Context));
    break;
  }
 
  return std::move(AsmStreamer);
}
 
bool LLVMTargetMachine::addPassesToEmitFile(
    PassManagerBase &PM, raw_pwrite_stream &Out, raw_pwrite_stream *DwoOut,
    CodeGenFileType FileType, bool DisableVerify,
    MachineModuleInfoWrapperPass *MMIWP) {
  // Add common CodeGen passes.
  if (!MMIWP)
    MMIWP = new MachineModuleInfoWrapperPass(this);
  TargetPassConfig *PassConfig =
      addPassesToGenerateCode(*this, PM, DisableVerify, *MMIWP);
  if (!PassConfig)
    return true;
 
  if (TargetPassConfig::willCompleteCodeGenPipeline()) {
    if (addAsmPrinter(PM, Out, DwoOut, FileType, MMIWP->getMMI().getContext()))
      return true;
  } else {
    // MIR printing is redundant with -filetype=null.
    if (FileType != CodeGenFileType::Null)
      PM.add(createPrintMIRPass(Out));
  }
 
  PM.add(createFreeMachineFunctionPass());
  return false;
}
 
/// addPassesToEmitMC - Add passes to the specified pass manager to get
/// machine code emitted with the MCJIT. This method returns true if machine
/// code is not supported. It fills the MCContext Ctx pointer which can be
/// used to build custom MCStreamer.
///
bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
                                          raw_pwrite_stream &Out,
                                          bool DisableVerify) {
  // Add common CodeGen passes.
  MachineModuleInfoWrapperPass *MMIWP = new MachineModuleInfoWrapperPass(this);
  TargetPassConfig *PassConfig =
      addPassesToGenerateCode(*this, PM, DisableVerify, *MMIWP);
  if (!PassConfig)
    return true;
  assert(TargetPassConfig::willCompleteCodeGenPipeline() &&
         "Cannot emit MC with limited codegen pipeline");
 
  Ctx = &MMIWP->getMMI().getContext();
  // libunwind is unable to load compact unwind dynamically, so we must generate
  // DWARF unwind info for the JIT.
  Options.MCOptions.EmitDwarfUnwind = EmitDwarfUnwindType::Always;
  if (Options.MCOptions.MCSaveTempLabels)
    Ctx->setAllowTemporaryLabels(false);
 
  // Create the code emitter for the target if it exists.  If not, .o file
  // emission fails.
  const MCSubtargetInfo &STI = *getMCSubtargetInfo();
  const MCRegisterInfo &MRI = *getMCRegisterInfo();
  std::unique_ptr<MCCodeEmitter> MCE(
      getTarget().createMCCodeEmitter(*getMCInstrInfo(), *Ctx));
  std::unique_ptr<MCAsmBackend> MAB(
      getTarget().createMCAsmBackend(STI, MRI, Options.MCOptions));
  if (!MCE || !MAB)
    return true;
 
  const Triple &T = getTargetTriple();
  std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
      T, *Ctx, std::move(MAB), MAB->createObjectWriter(Out), std::move(MCE),
      STI, Options.MCOptions.MCRelaxAll,
      Options.MCOptions.MCIncrementalLinkerCompatible,
      /*DWARFMustBeAtTheEnd*/ true));
 
  // Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
  FunctionPass *Printer =
      getTarget().createAsmPrinter(*this, std::move(AsmStreamer));
  if (!Printer)
    return true;
 
  PM.add(Printer);
  PM.add(createFreeMachineFunctionPass());
 
  return false; // success!
}