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//===-- MipsTargetMachine.cpp - Define TargetMachine for Mips -------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Implements the info about Mips target spec.
#include "MipsTargetMachine.h"
#include "MCTargetDesc/MipsABIInfo.h"
#include "MCTargetDesc/MipsMCTargetDesc.h"
#include "Mips.h"
#include "Mips16ISelDAGToDAG.h"
#include "MipsMachineFunction.h"
#include "MipsSEISelDAGToDAG.h"
#include "MipsSubtarget.h"
#include "MipsTargetObjectFile.h"
#include "MipsTargetTransformInfo.h"
#include "TargetInfo/MipsTargetInfo.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/CodeGen/GlobalISel/CSEInfo.h"
#include "llvm/CodeGen/GlobalISel/IRTranslator.h"
#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
#include "llvm/CodeGen/GlobalISel/Legalizer.h"
#include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Function.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetOptions.h"
#include <optional>
#include <string>
using namespace llvm;
#define DEBUG_TYPE "mips"
static cl::opt<bool>
EnableMulMulFix("mfix4300", cl::init(false),
cl::desc("Enable the VR4300 mulmul bug fix."), cl::Hidden);
extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeMipsTarget() {
// Register the target.
RegisterTargetMachine<MipsebTargetMachine> X(getTheMipsTarget());
RegisterTargetMachine<MipselTargetMachine> Y(getTheMipselTarget());
RegisterTargetMachine<MipsebTargetMachine> A(getTheMips64Target());
RegisterTargetMachine<MipselTargetMachine> B(getTheMips64elTarget());
PassRegistry *PR = PassRegistry::getPassRegistry();
static std::string computeDataLayout(const Triple &TT, StringRef CPU,
const TargetOptions &Options,
bool isLittle) {
std::string Ret;
MipsABIInfo ABI = MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions);
// There are both little and big endian mips.
if (isLittle)
Ret += "e";
Ret += "E";
if (ABI.IsO32())
Ret += "-m:m";
Ret += "-m:e";
// Pointers are 32 bit on some ABIs.
if (!ABI.IsN64())
Ret += "-p:32:32";
// 8 and 16 bit integers only need to have natural alignment, but try to
// align them to 32 bits. 64 bit integers have natural alignment.
Ret += "-i8:8:32-i16:16:32-i64:64";
// 32 bit registers are always available and the stack is at least 64 bit
// aligned. On N64 64 bit registers are also available and the stack is
// 128 bit aligned.
if (ABI.IsN64() || ABI.IsN32())
Ret += "-n32:64-S128";
Ret += "-n32-S64";
return Ret;
static Reloc::Model getEffectiveRelocModel(bool JIT,
std::optional<Reloc::Model> RM) {
if (!RM || JIT)
return Reloc::Static;
return *RM;
// On function prologue, the stack is created by decrementing
// its pointer. Once decremented, all references are done with positive
// offset from the stack/frame pointer, using StackGrowsUp enables
// an easier handling.
// Using CodeModel::Large enables different CALL behavior.
MipsTargetMachine::MipsTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
std::optional<Reloc::Model> RM,
std::optional<CodeModel::Model> CM,
CodeGenOptLevel OL, bool JIT,
bool isLittle)
: LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
CPU, FS, Options, getEffectiveRelocModel(JIT, RM),
getEffectiveCodeModel(CM, CodeModel::Small), OL),
isLittle(isLittle), TLOF(std::make_unique<MipsTargetObjectFile>()),
ABI(MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions)),
DefaultSubtarget(TT, CPU, FS, isLittle, *this, std::nullopt),
NoMips16Subtarget(TT, CPU, FS.empty() ? "-mips16" : FS.str() + ",-mips16",
isLittle, *this, std::nullopt),
Mips16Subtarget(TT, CPU, FS.empty() ? "+mips16" : FS.str() + ",+mips16",
isLittle, *this, std::nullopt) {
Subtarget = &DefaultSubtarget;
// Mips supports the debug entry values.
MipsTargetMachine::~MipsTargetMachine() = default;
void MipsebTargetMachine::anchor() {}
MipsebTargetMachine::MipsebTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
std::optional<Reloc::Model> RM,
std::optional<CodeModel::Model> CM,
CodeGenOptLevel OL, bool JIT)
: MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, false) {}
void MipselTargetMachine::anchor() {}
MipselTargetMachine::MipselTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
std::optional<Reloc::Model> RM,
std::optional<CodeModel::Model> CM,
CodeGenOptLevel OL, bool JIT)
: MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, true) {}
const MipsSubtarget *
MipsTargetMachine::getSubtargetImpl(const Function &F) const {
Attribute CPUAttr = F.getFnAttribute("target-cpu");
Attribute FSAttr = F.getFnAttribute("target-features");
std::string CPU =
CPUAttr.isValid() ? CPUAttr.getValueAsString().str() : TargetCPU;
std::string FS =
FSAttr.isValid() ? FSAttr.getValueAsString().str() : TargetFS;
bool hasMips16Attr = F.getFnAttribute("mips16").isValid();
bool hasNoMips16Attr = F.getFnAttribute("nomips16").isValid();
bool HasMicroMipsAttr = F.getFnAttribute("micromips").isValid();
bool HasNoMicroMipsAttr = F.getFnAttribute("nomicromips").isValid();
// 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, so we can enable it as a subtarget feature.
bool softFloat = F.getFnAttribute("use-soft-float").getValueAsBool();
if (hasMips16Attr)
FS += FS.empty() ? "+mips16" : ",+mips16";
else if (hasNoMips16Attr)
FS += FS.empty() ? "-mips16" : ",-mips16";
if (HasMicroMipsAttr)
FS += FS.empty() ? "+micromips" : ",+micromips";
else if (HasNoMicroMipsAttr)
FS += FS.empty() ? "-micromips" : ",-micromips";
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.
I = std::make_unique<MipsSubtarget>(
TargetTriple, CPU, FS, isLittle, *this,
return I.get();
void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
LLVM_DEBUG(dbgs() << "resetSubtarget\n");
Subtarget = &MF->getSubtarget<MipsSubtarget>();
namespace {
/// Mips Code Generator Pass Configuration Options.
class MipsPassConfig : public TargetPassConfig {
MipsPassConfig(MipsTargetMachine &TM, PassManagerBase &PM)
: TargetPassConfig(TM, PM) {
// The current implementation of long branch pass requires a scratch
// register ($at) to be available before branch instructions. Tail merging
// can break this requirement, so disable it when long branch pass is
// enabled.
EnableTailMerge = !getMipsSubtarget().enableLongBranchPass();
MipsTargetMachine &getMipsTargetMachine() const {
return getTM<MipsTargetMachine>();
const MipsSubtarget &getMipsSubtarget() const {
return *getMipsTargetMachine().getSubtargetImpl();
void addIRPasses() override;
bool addInstSelector() override;
void addPreEmitPass() override;
void addPreRegAlloc() override;
bool addIRTranslator() override;
void addPreLegalizeMachineIR() override;
bool addLegalizeMachineIR() override;
void addPreRegBankSelect() override;
bool addRegBankSelect() override;
bool addGlobalInstructionSelect() override;
std::unique_ptr<CSEConfigBase> getCSEConfig() const override;
} // end anonymous namespace
TargetPassConfig *MipsTargetMachine::createPassConfig(PassManagerBase &PM) {
return new MipsPassConfig(*this, PM);
std::unique_ptr<CSEConfigBase> MipsPassConfig::getCSEConfig() const {
return getStandardCSEConfigForOpt(TM->getOptLevel());
void MipsPassConfig::addIRPasses() {
if (getMipsSubtarget().os16())
if (getMipsSubtarget().inMips16HardFloat())
// Install an instruction selector pass using
// the ISelDag to gen Mips code.
bool MipsPassConfig::addInstSelector() {
addPass(createMips16ISelDag(getMipsTargetMachine(), getOptLevel()));
addPass(createMipsSEISelDag(getMipsTargetMachine(), getOptLevel()));
return false;
void MipsPassConfig::addPreRegAlloc() {
MipsTargetMachine::getTargetTransformInfo(const Function &F) const {
if (Subtarget->allowMixed16_32()) {
LLVM_DEBUG(errs() << "No Target Transform Info Pass Added\n");
// FIXME: This is no longer necessary as the TTI returned is per-function.
return TargetTransformInfo(F.getParent()->getDataLayout());
LLVM_DEBUG(errs() << "Target Transform Info Pass Added\n");
return TargetTransformInfo(MipsTTIImpl(this, F));
MachineFunctionInfo *MipsTargetMachine::createMachineFunctionInfo(
BumpPtrAllocator &Allocator, const Function &F,
const TargetSubtargetInfo *STI) const {
return MipsFunctionInfo::create<MipsFunctionInfo>(Allocator, F, STI);
// Implemented by targets that want to run passes immediately before
// machine code is emitted.
void MipsPassConfig::addPreEmitPass() {
// Expand pseudo instructions that are sensitive to register allocation.
// The microMIPS size reduction pass performs instruction reselection for
// instructions which can be remapped to a 16 bit instruction.
// This pass inserts a nop instruction between two back-to-back multiplication
// instructions when the "mfix4300" flag is passed.
if (EnableMulMulFix)
// The delay slot filler pass can potientially create forbidden slot hazards
// for MIPSR6 and therefore it should go before MipsBranchExpansion pass.
// This pass expands branches and takes care about the forbidden slot hazards.
// Expanding branches may potentially create forbidden slot hazards for
// MIPSR6, and fixing such hazard may potentially break a branch by extending
// its offset out of range. That's why this pass combine these two tasks, and
// runs them alternately until one of them finishes without any changes. Only
// then we can be sure that all branches are expanded properly and no hazards
// exists.
// Any new pass should go before this pass.
bool MipsPassConfig::addIRTranslator() {
addPass(new IRTranslator(getOptLevel()));
return false;
void MipsPassConfig::addPreLegalizeMachineIR() {
bool MipsPassConfig::addLegalizeMachineIR() {
addPass(new Legalizer());
return false;
void MipsPassConfig::addPreRegBankSelect() {
bool IsOptNone = getOptLevel() == CodeGenOptLevel::None;
bool MipsPassConfig::addRegBankSelect() {
addPass(new RegBankSelect());
return false;
bool MipsPassConfig::addGlobalInstructionSelect() {
addPass(new InstructionSelect(getOptLevel()));
return false;