path: root/lib/Target/ARM/ARMTargetMachine.cpp

//===-- ARMTargetMachine.cpp - Define TargetMachine for ARM ---------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//

#include "ARM.h"
#include "ARMTargetMachine.h"
#include "ARMFrameLowering.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/PassManager.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;

static cl::opt<bool>
DisableA15SDOptimization("disable-a15-sd-optimization", cl::Hidden,
                   cl::desc("Inhibit optimization of S->D register accesses on A15"),
                   cl::init(false));

static cl::opt<bool>
EnableAtomicTidy("arm-atomic-cfg-tidy", cl::Hidden,
                 cl::desc("Run SimplifyCFG after expanding atomic operations"
                          " to make use of cmpxchg flow-based information"),
                 cl::init(true));

extern "C" void LLVMInitializeARMTarget() {
  // Register the target.
  RegisterTargetMachine<ARMLETargetMachine> X(TheARMLETarget);
  RegisterTargetMachine<ARMBETargetMachine> Y(TheARMBETarget);
  RegisterTargetMachine<ThumbLETargetMachine> A(TheThumbLETarget);
  RegisterTargetMachine<ThumbBETargetMachine> B(TheThumbBETarget);
}


/// TargetMachine ctor - Create an ARM architecture model.
///
ARMBaseTargetMachine::ARMBaseTargetMachine(const Target &T, StringRef TT,
                                           StringRef CPU, StringRef FS,
                                           const TargetOptions &Options,
                                           Reloc::Model RM, CodeModel::Model CM,
                                           CodeGenOpt::Level OL,
                                           bool isLittle)
  : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
    Subtarget(TT, CPU, FS, isLittle, Options),
    JITInfo(),
    InstrItins(Subtarget.getInstrItineraryData()) {

  // Default to triple-appropriate float ABI
  if (Options.FloatABIType == FloatABI::Default)
    this->Options.FloatABIType =
        Subtarget.isTargetHardFloat() ? FloatABI::Hard : FloatABI::Soft;
}

void ARMBaseTargetMachine::addAnalysisPasses(PassManagerBase &PM) {
  // Add first the target-independent BasicTTI pass, then our ARM pass. This
  // allows the ARM pass to delegate to the target independent layer when
  // appropriate.
  PM.add(createBasicTargetTransformInfoPass(this));
  PM.add(createARMTargetTransformInfoPass(this));
}


void ARMTargetMachine::anchor() { }

static std::string computeDataLayout(ARMSubtarget &ST) {
  std::string Ret = "";

  if (ST.isLittle())
    // Little endian.
    Ret += "e";
  else
    // Big endian.
    Ret += "E";

  Ret += DataLayout::getManglingComponent(ST.getTargetTriple());

  // Pointers are 32 bits and aligned to 32 bits.
  Ret += "-p:32:32";

  // On thumb, i16,i18 and i1 have natural aligment requirements, but we try to
  // align to 32.
  if (ST.isThumb())
    Ret += "-i1:8:32-i8:8:32-i16:16:32";

  // ABIs other than APCS have 64 bit integers with natural alignment.
  if (!ST.isAPCS_ABI())
    Ret += "-i64:64";

  // We have 64 bits floats. The APCS ABI requires them to be aligned to 32
  // bits, others to 64 bits. We always try to align to 64 bits.
  if (ST.isAPCS_ABI())
    Ret += "-f64:32:64";

  // We have 128 and 64 bit vectors. The APCS ABI aligns them to 32 bits, others
  // to 64. We always ty to give them natural alignment.
  if (ST.isAPCS_ABI())
    Ret += "-v64:32:64-v128:32:128";
  else
    Ret += "-v128:64:128";

  // On thumb and APCS, only try to align aggregates to 32 bits (the default is
  // 64 bits).
  if (ST.isThumb() || ST.isAPCS_ABI())
    Ret += "-a:0:32";

  // Integer registers are 32 bits.
  Ret += "-n32";

  // The stack is 128 bit aligned on NaCl, 64 bit aligned on AAPCS and 32 bit
  // aligned everywhere else.
  if (ST.isTargetNaCl())
    Ret += "-S128";
  else if (ST.isAAPCS_ABI())
    Ret += "-S64";
  else
    Ret += "-S32";

  return Ret;
}

ARMTargetMachine::ARMTargetMachine(const Target &T, StringRef TT,
                                   StringRef CPU, StringRef FS,
                                   const TargetOptions &Options,
                                   Reloc::Model RM, CodeModel::Model CM,
                                   CodeGenOpt::Level OL,
                                   bool isLittle)
  : ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, isLittle),
    InstrInfo(Subtarget),
    DL(computeDataLayout(Subtarget)),
    TLInfo(*this),
    TSInfo(*this),
    FrameLowering(Subtarget) {
  initAsmInfo();
  if (!Subtarget.hasARMOps())
    report_fatal_error("CPU: '" + Subtarget.getCPUString() + "' does not "
                       "support ARM mode execution!");
}

void ARMLETargetMachine::anchor() { }

ARMLETargetMachine::
ARMLETargetMachine(const Target &T, StringRef TT,
                       StringRef CPU, StringRef FS, const TargetOptions &Options,
                       Reloc::Model RM, CodeModel::Model CM,
                       CodeGenOpt::Level OL)
  : ARMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}

void ARMBETargetMachine::anchor() { }

ARMBETargetMachine::
ARMBETargetMachine(const Target &T, StringRef TT,
                       StringRef CPU, StringRef FS, const TargetOptions &Options,
                       Reloc::Model RM, CodeModel::Model CM,
                       CodeGenOpt::Level OL)
  : ARMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, false) {}

void ThumbTargetMachine::anchor() { }

ThumbTargetMachine::ThumbTargetMachine(const Target &T, StringRef TT,
                                       StringRef CPU, StringRef FS,
                                       const TargetOptions &Options,
                                       Reloc::Model RM, CodeModel::Model CM,
                                       CodeGenOpt::Level OL,
                                       bool isLittle)
  : ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, isLittle),
    InstrInfo(Subtarget.hasThumb2()
              ? ((ARMBaseInstrInfo*)new Thumb2InstrInfo(Subtarget))
              : ((ARMBaseInstrInfo*)new Thumb1InstrInfo(Subtarget))),
    DL(computeDataLayout(Subtarget)),
    TLInfo(*this),
    TSInfo(*this),
    FrameLowering(Subtarget.hasThumb2()
              ? new ARMFrameLowering(Subtarget)
              : (ARMFrameLowering*)new Thumb1FrameLowering(Subtarget)) {
  initAsmInfo();
}

void ThumbLETargetMachine::anchor() { }

ThumbLETargetMachine::
ThumbLETargetMachine(const Target &T, StringRef TT,
                       StringRef CPU, StringRef FS, const TargetOptions &Options,
                       Reloc::Model RM, CodeModel::Model CM,
                       CodeGenOpt::Level OL)
  : ThumbTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}

void ThumbBETargetMachine::anchor() { }

ThumbBETargetMachine::
ThumbBETargetMachine(const Target &T, StringRef TT,
                       StringRef CPU, StringRef FS, const TargetOptions &Options,
                       Reloc::Model RM, CodeModel::Model CM,
                       CodeGenOpt::Level OL)
  : ThumbTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, false) {}

namespace {
/// ARM Code Generator Pass Configuration Options.
class ARMPassConfig : public TargetPassConfig {
public:
  ARMPassConfig(ARMBaseTargetMachine *TM, PassManagerBase &PM)
    : TargetPassConfig(TM, PM) {}

  ARMBaseTargetMachine &getARMTargetMachine() const {
    return getTM<ARMBaseTargetMachine>();
  }

  const ARMSubtarget &getARMSubtarget() const {
    return *getARMTargetMachine().getSubtargetImpl();
  }

  void addIRPasses() override;
  bool addPreISel() override;
  bool addInstSelector() override;
  bool addPreRegAlloc() override;
  bool addPreSched2() override;
  bool addPreEmitPass() override;
};
} // namespace

TargetPassConfig *ARMBaseTargetMachine::createPassConfig(PassManagerBase &PM) {
  return new ARMPassConfig(this, PM);
}

void ARMPassConfig::addIRPasses() {
  const ARMSubtarget *Subtarget = &getARMSubtarget();
  if (Subtarget->hasAnyDataBarrier() && !Subtarget->isThumb1Only()) {
    addPass(createAtomicExpandLoadLinkedPass(TM));

    // Cmpxchg instructions are often used with a subsequent comparison to
    // determine whether it succeeded. We can exploit existing control-flow in
    // ldrex/strex loops to simplify this, but it needs tidying up.
    if (TM->getOptLevel() != CodeGenOpt::None && EnableAtomicTidy)
      addPass(createCFGSimplificationPass());
  }

  TargetPassConfig::addIRPasses();
}

bool ARMPassConfig::addPreISel() {
  if (TM->getOptLevel() != CodeGenOpt::None)
    addPass(createGlobalMergePass(TM));

  return false;
}

bool ARMPassConfig::addInstSelector() {
  addPass(createARMISelDag(getARMTargetMachine(), getOptLevel()));

  const ARMSubtarget *Subtarget = &getARMSubtarget();
  if (Subtarget->isTargetELF() && !Subtarget->isThumb1Only() &&
      TM->Options.EnableFastISel)
    addPass(createARMGlobalBaseRegPass());
  return false;
}

bool ARMPassConfig::addPreRegAlloc() {
  // FIXME: Temporarily disabling Thumb-1 pre-RA Load/Store optimization pass
  if (getOptLevel() != CodeGenOpt::None && !getARMSubtarget().isThumb1Only())
    addPass(createARMLoadStoreOptimizationPass(true));
  if (getOptLevel() != CodeGenOpt::None && getARMSubtarget().isCortexA9())
    addPass(createMLxExpansionPass());
  // Since the A15SDOptimizer pass can insert VDUP instructions, it can only be
  // enabled when NEON is available.
  if (getOptLevel() != CodeGenOpt::None && getARMSubtarget().isCortexA15() &&
    getARMSubtarget().hasNEON() && !DisableA15SDOptimization) {
    addPass(createA15SDOptimizerPass());
  }
  return true;
}

bool ARMPassConfig::addPreSched2() {
  if (getOptLevel() != CodeGenOpt::None) {
    // FIXME: Temporarily disabling Thumb-1 post-RA Load/Store optimization pass
    if (!getARMSubtarget().isThumb1Only()) {
      addPass(createARMLoadStoreOptimizationPass());
      printAndVerify("After ARM load / store optimizer");
    }

    if (getARMSubtarget().hasNEON())
      addPass(createExecutionDependencyFixPass(&ARM::DPRRegClass));
  }

  // Expand some pseudo instructions into multiple instructions to allow
  // proper scheduling.
  addPass(createARMExpandPseudoPass());

  if (getOptLevel() != CodeGenOpt::None) {
    if (!getARMSubtarget().isThumb1Only()) {
      // in v8, IfConversion depends on Thumb instruction widths
      if (getARMSubtarget().restrictIT() &&
          !getARMSubtarget().prefers32BitThumb())
        addPass(createThumb2SizeReductionPass());
      addPass(&IfConverterID);
    }
  }
  if (getARMSubtarget().isThumb2())
    addPass(createThumb2ITBlockPass());

  return true;
}

bool ARMPassConfig::addPreEmitPass() {
  if (getARMSubtarget().isThumb2()) {
    if (!getARMSubtarget().prefers32BitThumb())
      addPass(createThumb2SizeReductionPass());

    // Constant island pass work on unbundled instructions.
    addPass(&UnpackMachineBundlesID);
  }

  addPass(createARMOptimizeBarriersPass());
  addPass(createARMConstantIslandPass());

  return true;
}

bool ARMBaseTargetMachine::addCodeEmitter(PassManagerBase &PM,
                                          JITCodeEmitter &JCE) {
  // Machine code emitter pass for ARM.
  PM.add(createARMJITCodeEmitterPass(*this, JCE));
  return false;
}