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llvm-mirror/lib/Target/ARM/ARMTargetMachine.cpp
Diana Picus e302afcbd6 [ARM] GlobalISel: Use Subtarget in Legalizer 
Start using the Subtarget to make decisions about what's legal. In particular,
we only mark floating point operations as legal if we have VFP2, which is
something we should've done from the very start.

llvm-svn: 295439
2017-02-17 11:25:17 +00:00

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//===-- 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 "ARMCallLowering.h"
#include "ARMInstructionSelector.h"
#include "ARMLegalizerInfo.h"
#include "ARMRegisterBankInfo.h"
#include "ARMSubtarget.h"
#include "ARMTargetMachine.h"
#include "ARMTargetObjectFile.h"
#include "ARMTargetTransformInfo.h"
#include "MCTargetDesc/ARMMCTargetDesc.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/GlobalISel/CallLowering.h"
#include "llvm/CodeGen/GlobalISel/GISelAccessor.h"
#include "llvm/CodeGen/GlobalISel/IRTranslator.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
#include "llvm/CodeGen/GlobalISel/Legalizer.h"
#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
#include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Pass.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetParser.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Scalar.h"
#include <cassert>
#include <memory>
#include <string>
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));
static cl::opt<bool>
EnableARMLoadStoreOpt("arm-load-store-opt", cl::Hidden,
cl::desc("Enable ARM load/store optimization pass"),
cl::init(true));
// FIXME: Unify control over GlobalMerge.
static cl::opt<cl::boolOrDefault>
EnableGlobalMerge("arm-global-merge", cl::Hidden,
cl::desc("Enable the global merge pass"));
extern "C" void LLVMInitializeARMTarget() {
// Register the target.
RegisterTargetMachine<ARMLETargetMachine> X(getTheARMLETarget());
RegisterTargetMachine<ARMBETargetMachine> Y(getTheARMBETarget());
RegisterTargetMachine<ThumbLETargetMachine> A(getTheThumbLETarget());
RegisterTargetMachine<ThumbBETargetMachine> B(getTheThumbBETarget());
PassRegistry &Registry = *PassRegistry::getPassRegistry();
initializeGlobalISel(Registry);
initializeARMLoadStoreOptPass(Registry);
initializeARMPreAllocLoadStoreOptPass(Registry);
initializeARMConstantIslandsPass(Registry);
}
static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {
if (TT.isOSBinFormatMachO())
return llvm::make_unique<TargetLoweringObjectFileMachO>();
if (TT.isOSWindows())
return llvm::make_unique<TargetLoweringObjectFileCOFF>();
return llvm::make_unique<ARMElfTargetObjectFile>();
}
static ARMBaseTargetMachine::ARMABI
computeTargetABI(const Triple &TT, StringRef CPU,
const TargetOptions &Options) {
if (Options.MCOptions.getABIName() == "aapcs16")
return ARMBaseTargetMachine::ARM_ABI_AAPCS16;
else if (Options.MCOptions.getABIName().startswith("aapcs"))
return ARMBaseTargetMachine::ARM_ABI_AAPCS;
else if (Options.MCOptions.getABIName().startswith("apcs"))
return ARMBaseTargetMachine::ARM_ABI_APCS;
assert(Options.MCOptions.getABIName().empty() &&
"Unknown target-abi option!");
ARMBaseTargetMachine::ARMABI TargetABI =
ARMBaseTargetMachine::ARM_ABI_UNKNOWN;
unsigned ArchKind = ARM::parseCPUArch(CPU);
StringRef ArchName = ARM::getArchName(ArchKind);
// FIXME: This is duplicated code from the front end and should be unified.
if (TT.isOSBinFormatMachO()) {
if (TT.getEnvironment() == Triple::EABI ||
(TT.getOS() == Triple::UnknownOS && TT.isOSBinFormatMachO()) ||
ARM::parseArchProfile(ArchName) == ARM::PK_M) {
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
} else if (TT.isWatchABI()) {
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS16;
} else {
TargetABI = ARMBaseTargetMachine::ARM_ABI_APCS;
}
} else if (TT.isOSWindows()) {
// FIXME: this is invalid for WindowsCE
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
} else {
// Select the default based on the platform.
switch (TT.getEnvironment()) {
case Triple::Android:
case Triple::GNUEABI:
case Triple::GNUEABIHF:
case Triple::MuslEABI:
case Triple::MuslEABIHF:
case Triple::EABIHF:
case Triple::EABI:
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
break;
case Triple::GNU:
TargetABI = ARMBaseTargetMachine::ARM_ABI_APCS;
break;
default:
if (TT.isOSNetBSD())
TargetABI = ARMBaseTargetMachine::ARM_ABI_APCS;
else
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
break;
}
}
return TargetABI;
}
static std::string computeDataLayout(const Triple &TT, StringRef CPU,
const TargetOptions &Options,
bool isLittle) {
auto ABI = computeTargetABI(TT, CPU, Options);
std::string Ret;
if (isLittle)
// Little endian.
Ret += "e";
else
// Big endian.
Ret += "E";
Ret += DataLayout::getManglingComponent(TT);
// Pointers are 32 bits and aligned to 32 bits.
Ret += "-p:32:32";
// ABIs other than APCS have 64 bit integers with natural alignment.
if (ABI != ARMBaseTargetMachine::ARM_ABI_APCS)
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 (ABI == ARMBaseTargetMachine::ARM_ABI_APCS)
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 (ABI == ARMBaseTargetMachine::ARM_ABI_APCS)
Ret += "-v64:32:64-v128:32:128";
else if (ABI != ARMBaseTargetMachine::ARM_ABI_AAPCS16)
Ret += "-v128:64:128";
// Try to align aggregates to 32 bits (the default is 64 bits, which has no
// particular hardware support on 32-bit ARM).
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 (TT.isOSNaCl() || ABI == ARMBaseTargetMachine::ARM_ABI_AAPCS16)
Ret += "-S128";
else if (ABI == ARMBaseTargetMachine::ARM_ABI_AAPCS)
Ret += "-S64";
else
Ret += "-S32";
return Ret;
}
static Reloc::Model getEffectiveRelocModel(const Triple &TT,
Optional<Reloc::Model> RM) {
if (!RM.hasValue())
// Default relocation model on Darwin is PIC.
return TT.isOSBinFormatMachO() ? Reloc::PIC_ : Reloc::Static;
if (*RM == Reloc::ROPI || *RM == Reloc::RWPI || *RM == Reloc::ROPI_RWPI)
assert(TT.isOSBinFormatELF() &&
"ROPI/RWPI currently only supported for ELF");
// DynamicNoPIC is only used on darwin.
if (*RM == Reloc::DynamicNoPIC && !TT.isOSDarwin())
return Reloc::Static;
return *RM;
}
/// Create an ARM architecture model.
///
ARMBaseTargetMachine::ARMBaseTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<Reloc::Model> RM,
CodeModel::Model CM,
CodeGenOpt::Level OL, bool isLittle)
: LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
CPU, FS, Options, getEffectiveRelocModel(TT, RM), CM,
OL),
TargetABI(computeTargetABI(TT, CPU, Options)),
TLOF(createTLOF(getTargetTriple())),
Subtarget(TT, CPU, FS, *this, isLittle), isLittle(isLittle) {
// Default to triple-appropriate float ABI
if (Options.FloatABIType == FloatABI::Default)
this->Options.FloatABIType =
Subtarget.isTargetHardFloat() ? FloatABI::Hard : FloatABI::Soft;
// Default to triple-appropriate EABI
if (Options.EABIVersion == EABI::Default ||
Options.EABIVersion == EABI::Unknown) {
// musl is compatible with glibc with regard to EABI version
if (Subtarget.isTargetGNUAEABI() || Subtarget.isTargetMuslAEABI())
this->Options.EABIVersion = EABI::GNU;
else
this->Options.EABIVersion = EABI::EABI5;
}
}
ARMBaseTargetMachine::~ARMBaseTargetMachine() = default;
#ifdef LLVM_BUILD_GLOBAL_ISEL
namespace {
struct ARMGISelActualAccessor : public GISelAccessor {
std::unique_ptr<CallLowering> CallLoweringInfo;
std::unique_ptr<InstructionSelector> InstSelector;
std::unique_ptr<LegalizerInfo> Legalizer;
std::unique_ptr<RegisterBankInfo> RegBankInfo;
const CallLowering *getCallLowering() const override {
return CallLoweringInfo.get();
}
const InstructionSelector *getInstructionSelector() const override {
return InstSelector.get();
}
const LegalizerInfo *getLegalizerInfo() const override {
return Legalizer.get();
}
const RegisterBankInfo *getRegBankInfo() const override {
return RegBankInfo.get();
}
};
} // end anonymous namespace
#endif
const ARMSubtarget *
ARMBaseTargetMachine::getSubtargetImpl(const Function &F) const {
Attribute CPUAttr = F.getFnAttribute("target-cpu");
Attribute FSAttr = F.getFnAttribute("target-features");
std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
? CPUAttr.getValueAsString().str()
: TargetCPU;
std::string FS = !FSAttr.hasAttribute(Attribute::None)
? FSAttr.getValueAsString().str()
: TargetFS;
// FIXME: This is related to the code below to reset the target options,
// we need to know whether or not the soft float flag is set on the
// function before we can generate a subtarget. We also need to use
// it as a key for the subtarget since that can be the only difference
// between two functions.
bool SoftFloat =
F.getFnAttribute("use-soft-float").getValueAsString() == "true";
// If the soft float attribute is set on the function turn on the soft float
// subtarget feature.
if (SoftFloat)
FS += FS.empty() ? "+soft-float" : ",+soft-float";
auto &I = SubtargetMap[CPU + FS];
if (!I) {
// This needs to be done before we create a new subtarget since any
// creation will depend on the TM and the code generation flags on the
// function that reside in TargetOptions.
resetTargetOptions(F);
I = llvm::make_unique<ARMSubtarget>(TargetTriple, CPU, FS, *this, isLittle);
#ifndef LLVM_BUILD_GLOBAL_ISEL
GISelAccessor *GISel = new GISelAccessor();
#else
ARMGISelActualAccessor *GISel = new ARMGISelActualAccessor();
GISel->CallLoweringInfo.reset(new ARMCallLowering(*I->getTargetLowering()));
GISel->Legalizer.reset(new ARMLegalizerInfo(*I));
auto *RBI = new ARMRegisterBankInfo(*I->getRegisterInfo());
// FIXME: At this point, we can't rely on Subtarget having RBI.
// It's awkward to mix passing RBI and the Subtarget; should we pass
// TII/TRI as well?
GISel->InstSelector.reset(new ARMInstructionSelector(*I, *RBI));
GISel->RegBankInfo.reset(RBI);
#endif
I->setGISelAccessor(*GISel);
}
return I.get();
}
TargetIRAnalysis ARMBaseTargetMachine::getTargetIRAnalysis() {
return TargetIRAnalysis([this](const Function &F) {
return TargetTransformInfo(ARMTTIImpl(this, F));
});
}
void ARMTargetMachine::anchor() {}
ARMTargetMachine::ARMTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<Reloc::Model> RM,
CodeModel::Model CM, CodeGenOpt::Level OL,
bool isLittle)
: ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, isLittle) {
initAsmInfo();
if (!Subtarget.hasARMOps())
report_fatal_error("CPU: '" + Subtarget.getCPUString() + "' does not "
"support ARM mode execution!");
}
void ARMLETargetMachine::anchor() {}
ARMLETargetMachine::ARMLETargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<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, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<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, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<Reloc::Model> RM,
CodeModel::Model CM,
CodeGenOpt::Level OL, bool isLittle)
: ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, isLittle) {
initAsmInfo();
}
void ThumbLETargetMachine::anchor() {}
ThumbLETargetMachine::ThumbLETargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<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, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<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>();
}
void addIRPasses() override;
bool addPreISel() override;
bool addInstSelector() override;
#ifdef LLVM_BUILD_GLOBAL_ISEL
bool addIRTranslator() override;
bool addLegalizeMachineIR() override;
bool addRegBankSelect() override;
bool addGlobalInstructionSelect() override;
#endif
void addPreRegAlloc() override;
void addPreSched2() override;
void addPreEmitPass() override;
};
} // end anonymous namespace
TargetPassConfig *ARMBaseTargetMachine::createPassConfig(PassManagerBase &PM) {
return new ARMPassConfig(this, PM);
}
void ARMPassConfig::addIRPasses() {
if (TM->Options.ThreadModel == ThreadModel::Single)
addPass(createLowerAtomicPass());
else
addPass(createAtomicExpandPass(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(-1, [this](const Function &F) {
const auto &ST = this->TM->getSubtarget<ARMSubtarget>(F);
return ST.hasAnyDataBarrier() && !ST.isThumb1Only();
}));
TargetPassConfig::addIRPasses();
// Match interleaved memory accesses to ldN/stN intrinsics.
if (TM->getOptLevel() != CodeGenOpt::None)
addPass(createInterleavedAccessPass(TM));
}
bool ARMPassConfig::addPreISel() {
if ((TM->getOptLevel() != CodeGenOpt::None &&
EnableGlobalMerge == cl::BOU_UNSET) ||
EnableGlobalMerge == cl::BOU_TRUE) {
// FIXME: This is using the thumb1 only constant value for
// maximal global offset for merging globals. We may want
// to look into using the old value for non-thumb1 code of
// 4095 based on the TargetMachine, but this starts to become
// tricky when doing code gen per function.
bool OnlyOptimizeForSize = (TM->getOptLevel() < CodeGenOpt::Aggressive) &&
(EnableGlobalMerge == cl::BOU_UNSET);
// Merging of extern globals is enabled by default on non-Mach-O as we
// expect it to be generally either beneficial or harmless. On Mach-O it
// is disabled as we emit the .subsections_via_symbols directive which
// means that merging extern globals is not safe.
bool MergeExternalByDefault = !TM->getTargetTriple().isOSBinFormatMachO();
addPass(createGlobalMergePass(TM, 127, OnlyOptimizeForSize,
MergeExternalByDefault));
}
return false;
}
bool ARMPassConfig::addInstSelector() {
addPass(createARMISelDag(getARMTargetMachine(), getOptLevel()));
return false;
}
#ifdef LLVM_BUILD_GLOBAL_ISEL
bool ARMPassConfig::addIRTranslator() {
addPass(new IRTranslator());
return false;
}
bool ARMPassConfig::addLegalizeMachineIR() {
addPass(new Legalizer());
return false;
}
bool ARMPassConfig::addRegBankSelect() {
addPass(new RegBankSelect());
return false;
}
bool ARMPassConfig::addGlobalInstructionSelect() {
addPass(new InstructionSelect());
return false;
}
#endif
void ARMPassConfig::addPreRegAlloc() {
if (getOptLevel() != CodeGenOpt::None) {
addPass(createMLxExpansionPass());
if (EnableARMLoadStoreOpt)
addPass(createARMLoadStoreOptimizationPass(/* pre-register alloc */ true));
if (!DisableA15SDOptimization)
addPass(createA15SDOptimizerPass());
}
}
void ARMPassConfig::addPreSched2() {
if (getOptLevel() != CodeGenOpt::None) {
if (EnableARMLoadStoreOpt)
addPass(createARMLoadStoreOptimizationPass());
addPass(createExecutionDependencyFixPass(&ARM::DPRRegClass));
}
// Expand some pseudo instructions into multiple instructions to allow
// proper scheduling.
addPass(createARMExpandPseudoPass());
if (getOptLevel() != CodeGenOpt::None) {
// in v8, IfConversion depends on Thumb instruction widths
addPass(createThumb2SizeReductionPass([this](const Function &F) {
return this->TM->getSubtarget<ARMSubtarget>(F).restrictIT();
}));
addPass(createIfConverter([](const MachineFunction &MF) {
return !MF.getSubtarget<ARMSubtarget>().isThumb1Only();
}));
}
addPass(createThumb2ITBlockPass());
}
void ARMPassConfig::addPreEmitPass() {
addPass(createThumb2SizeReductionPass());
// Constant island pass work on unbundled instructions.
addPass(createUnpackMachineBundles([](const MachineFunction &MF) {
return MF.getSubtarget<ARMSubtarget>().isThumb2();
}));
// Don't optimize barriers at -O0.
if (getOptLevel() != CodeGenOpt::None)
addPass(createARMOptimizeBarriersPass());
addPass(createARMConstantIslandPass());
}
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