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llvm-project/llvm/lib/Target/ARM/ARMTargetMachine.cpp

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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 "ARMFrameLowering.h"
#include "ARMTargetMachine.h"
#include "ARMTargetObjectFile.h"
#include "ARMTargetTransformInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/MC/MCAsmInfo.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));
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(TheARMLETarget);
RegisterTargetMachine<ARMBETargetMachine> Y(TheARMBETarget);
RegisterTargetMachine<ThumbLETargetMachine> A(TheThumbLETarget);
RegisterTargetMachine<ThumbBETargetMachine> B(TheThumbBETarget);
}
static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {
if (TT.isOSBinFormatMachO())
return make_unique<TargetLoweringObjectFileMachO>();
if (TT.isOSWindows())
return make_unique<TargetLoweringObjectFileCOFF>();
return 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;
// FIXME: This is duplicated code from the front end and should be unified.
if (TT.isOSBinFormatMachO()) {
if (TT.getEnvironment() == llvm::Triple::EABI ||
(TT.getOS() == llvm::Triple::UnknownOS && TT.isOSBinFormatMachO()) ||
CPU.startswith("cortex-m")) {
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
} else if (TT.isWatchOS()) {
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 llvm::Triple::Android:
case llvm::Triple::GNUEABI:
case llvm::Triple::GNUEABIHF:
case llvm::Triple::EABIHF:
case llvm::Triple::EABI:
TargetABI = ARMBaseTargetMachine::ARM_ABI_AAPCS;
break;
case llvm::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;
}
/// TargetMachine ctor - Create an ARM architecture model.
///
ARMBaseTargetMachine::ARMBaseTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Reloc::Model RM, CodeModel::Model CM,
CodeGenOpt::Level OL, bool isLittle)
: LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
CPU, FS, Options, 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) {
if (Subtarget.isTargetGNUAEABI())
this->Options.EABIVersion = EABI::GNU;
else
this->Options.EABIVersion = EABI::EABI5;
}
}
ARMBaseTargetMachine::~ARMBaseTargetMachine() {}
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.hasFnAttribute("use-soft-float") &&
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);
}
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,
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,
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,
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,
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,
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,
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;
void addPreRegAlloc() override;
void addPreSched2() override;
void addPreEmitPass() override;
};
} // 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;
}
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([this](const Function &F) {
return !this->TM->getSubtarget<ARMSubtarget>(F).isThumb1Only();
}));
}
addPass(createThumb2ITBlockPass());
}
void ARMPassConfig::addPreEmitPass() {
addPass(createThumb2SizeReductionPass());
// Constant island pass work on unbundled instructions.
addPass(createUnpackMachineBundles([this](const Function &F) {
return this->TM->getSubtarget<ARMSubtarget>(F).isThumb2();
}));
// Don't optimize barriers at -O0.
if (getOptLevel() != CodeGenOpt::None)
addPass(createARMOptimizeBarriersPass());
addPass(createARMConstantIslandPass());
}
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