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llvm-project/llvm/lib/Target/Mips/Mips16HardFloat.cpp

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//===---- Mips16HardFloat.cpp for Mips16 Hard Float --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pass needed for Mips16 Hard Float
//
//===----------------------------------------------------------------------===//
#include "MipsTargetMachine.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <string>
using namespace llvm;
#define DEBUG_TYPE "mips16-hard-float"
namespace {
class Mips16HardFloat : public ModulePass {
public:
static char ID;
Mips16HardFloat(MipsTargetMachine &TM_) : ModulePass(ID), TM(TM_) {}
const char *getPassName() const override {
return "MIPS16 Hard Float Pass";
}
bool runOnModule(Module &M) override;
protected:
const MipsTargetMachine &TM;
};
class InlineAsmHelper {
LLVMContext &C;
BasicBlock *BB;
public:
InlineAsmHelper(LLVMContext &C_, BasicBlock *BB_) :
C(C_), BB(BB_) {
}
void Out(StringRef AsmString) {
std::vector<llvm::Type *> AsmArgTypes;
std::vector<llvm::Value*> AsmArgs;
llvm::FunctionType *AsmFTy = llvm::FunctionType::get(Type::getVoidTy(C),
AsmArgTypes, false);
llvm::InlineAsm *IA = llvm::InlineAsm::get(AsmFTy, AsmString, "", true,
/* IsAlignStack */ false,
llvm::InlineAsm::AD_ATT);
CallInst::Create(IA, AsmArgs, "", BB);
}
};
char Mips16HardFloat::ID = 0;
}
//
// Return types that matter for hard float are:
// float, double, complex float, and complex double
//
enum FPReturnVariant {
FRet, DRet, CFRet, CDRet, NoFPRet
};
//
// Determine which FP return type this function has
//
static FPReturnVariant whichFPReturnVariant(Type *T) {
switch (T->getTypeID()) {
case Type::FloatTyID:
return FRet;
case Type::DoubleTyID:
return DRet;
case Type::StructTyID:
if (T->getStructNumElements() != 2)
break;
if ((T->getContainedType(0)->isFloatTy()) &&
(T->getContainedType(1)->isFloatTy()))
return CFRet;
if ((T->getContainedType(0)->isDoubleTy()) &&
(T->getContainedType(1)->isDoubleTy()))
return CDRet;
break;
default:
break;
}
return NoFPRet;
}
//
// Parameter type that matter are float, (float, float), (float, double),
// double, (double, double), (double, float)
//
enum FPParamVariant {
FSig, FFSig, FDSig,
DSig, DDSig, DFSig, NoSig
};
// which floating point parameter signature variant we are dealing with
//
typedef Type::TypeID TypeID;
const Type::TypeID FloatTyID = Type::FloatTyID;
const Type::TypeID DoubleTyID = Type::DoubleTyID;
static FPParamVariant whichFPParamVariantNeeded(Function &F) {
switch (F.arg_size()) {
case 0:
return NoSig;
case 1:{
TypeID ArgTypeID = F.getFunctionType()->getParamType(0)->getTypeID();
switch (ArgTypeID) {
case FloatTyID:
return FSig;
case DoubleTyID:
return DSig;
default:
return NoSig;
}
}
default: {
TypeID ArgTypeID0 = F.getFunctionType()->getParamType(0)->getTypeID();
TypeID ArgTypeID1 = F.getFunctionType()->getParamType(1)->getTypeID();
switch(ArgTypeID0) {
case FloatTyID: {
switch (ArgTypeID1) {
case FloatTyID:
return FFSig;
case DoubleTyID:
return FDSig;
default:
return FSig;
}
}
case DoubleTyID: {
switch (ArgTypeID1) {
case FloatTyID:
return DFSig;
case DoubleTyID:
return DDSig;
default:
return DSig;
}
}
default:
return NoSig;
}
}
}
llvm_unreachable("can't get here");
}
// Figure out if we need float point based on the function parameters.
// We need to move variables in and/or out of floating point
// registers because of the ABI
//
static bool needsFPStubFromParams(Function &F) {
if (F.arg_size() >=1) {
Type *ArgType = F.getFunctionType()->getParamType(0);
switch (ArgType->getTypeID()) {
case Type::FloatTyID:
case Type::DoubleTyID:
return true;
default:
break;
}
}
return false;
}
static bool needsFPReturnHelper(Function &F) {
Type* RetType = F.getReturnType();
return whichFPReturnVariant(RetType) != NoFPRet;
}
static bool needsFPReturnHelper(const FunctionType &FT) {
Type* RetType = FT.getReturnType();
return whichFPReturnVariant(RetType) != NoFPRet;
}
static bool needsFPHelperFromSig(Function &F) {
return needsFPStubFromParams(F) || needsFPReturnHelper(F);
}
//
// We swap between FP and Integer registers to allow Mips16 and Mips32 to
// interoperate
//
static void swapFPIntParams(FPParamVariant PV, Module *M, InlineAsmHelper &IAH,
bool LE, bool ToFP) {
//LLVMContext &Context = M->getContext();
std::string MI = ToFP? "mtc1 ": "mfc1 ";
switch (PV) {
case FSig:
IAH.Out(MI + "$$4,$$f12");
break;
case FFSig:
IAH.Out(MI +"$$4,$$f12");
IAH.Out(MI + "$$5,$$f14");
break;
case FDSig:
IAH.Out(MI + "$$4,$$f12");
if (LE) {
IAH.Out(MI + "$$6,$$f14");
IAH.Out(MI + "$$7,$$f15");
} else {
IAH.Out(MI + "$$7,$$f14");
IAH.Out(MI + "$$6,$$f15");
}
break;
case DSig:
if (LE) {
IAH.Out(MI + "$$4,$$f12");
IAH.Out(MI + "$$5,$$f13");
} else {
IAH.Out(MI + "$$5,$$f12");
IAH.Out(MI + "$$4,$$f13");
}
break;
case DDSig:
if (LE) {
IAH.Out(MI + "$$4,$$f12");
IAH.Out(MI + "$$5,$$f13");
IAH.Out(MI + "$$6,$$f14");
IAH.Out(MI + "$$7,$$f15");
} else {
IAH.Out(MI + "$$5,$$f12");
IAH.Out(MI + "$$4,$$f13");
IAH.Out(MI + "$$7,$$f14");
IAH.Out(MI + "$$6,$$f15");
}
break;
case DFSig:
if (LE) {
IAH.Out(MI + "$$4,$$f12");
IAH.Out(MI + "$$5,$$f13");
} else {
IAH.Out(MI + "$$5,$$f12");
IAH.Out(MI + "$$4,$$f13");
}
IAH.Out(MI + "$$6,$$f14");
break;
case NoSig:
return;
}
}
//
// Make sure that we know we already need a stub for this function.
// Having called needsFPHelperFromSig
//
static void assureFPCallStub(Function &F, Module *M,
const MipsTargetMachine &TM) {
// for now we only need them for static relocation
if (TM.getRelocationModel() == Reloc::PIC_)
return;
LLVMContext &Context = M->getContext();
bool LE = TM.isLittleEndian();
std::string Name = F.getName();
std::string SectionName = ".mips16.call.fp." + Name;
std::string StubName = "__call_stub_fp_" + Name;
//
// see if we already have the stub
//
Function *FStub = M->getFunction(StubName);
if (FStub && !FStub->isDeclaration()) return;
FStub = Function::Create(F.getFunctionType(),
Function::InternalLinkage, StubName, M);
FStub->addFnAttr("mips16_fp_stub");
FStub->addFnAttr(llvm::Attribute::Naked);
FStub->addFnAttr(llvm::Attribute::NoInline);
FStub->addFnAttr(llvm::Attribute::NoUnwind);
FStub->addFnAttr("nomips16");
FStub->setSection(SectionName);
BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
InlineAsmHelper IAH(Context, BB);
IAH.Out(".set reorder");
FPReturnVariant RV = whichFPReturnVariant(FStub->getReturnType());
FPParamVariant PV = whichFPParamVariantNeeded(F);
swapFPIntParams(PV, M, IAH, LE, true);
if (RV != NoFPRet) {
IAH.Out("move $$18, $$31");
IAH.Out("jal " + Name);
} else {
IAH.Out("lui $$25,%hi(" + Name + ")");
IAH.Out("addiu $$25,$$25,%lo(" + Name + ")" );
}
switch (RV) {
case FRet:
IAH.Out("mfc1 $$2,$$f0");
break;
case DRet:
if (LE) {
IAH.Out("mfc1 $$2,$$f0");
IAH.Out("mfc1 $$3,$$f1");
} else {
IAH.Out("mfc1 $$3,$$f0");
IAH.Out("mfc1 $$2,$$f1");
}
break;
case CFRet:
if (LE) {
IAH.Out("mfc1 $$2,$$f0");
IAH.Out("mfc1 $$3,$$f2");
} else {
IAH.Out("mfc1 $$3,$$f0");
IAH.Out("mfc1 $$3,$$f2");
}
break;
case CDRet:
if (LE) {
IAH.Out("mfc1 $$4,$$f2");
IAH.Out("mfc1 $$5,$$f3");
IAH.Out("mfc1 $$2,$$f0");
IAH.Out("mfc1 $$3,$$f1");
} else {
IAH.Out("mfc1 $$5,$$f2");
IAH.Out("mfc1 $$4,$$f3");
IAH.Out("mfc1 $$3,$$f0");
IAH.Out("mfc1 $$2,$$f1");
}
break;
case NoFPRet:
break;
}
if (RV != NoFPRet)
IAH.Out("jr $$18");
else
IAH.Out("jr $$25");
new UnreachableInst(Context, BB);
}
//
// Functions that are llvm intrinsics and don't need helpers.
//
static const char *IntrinsicInline[] = {
"fabs", "fabsf",
"llvm.ceil.f32", "llvm.ceil.f64",
"llvm.copysign.f32", "llvm.copysign.f64",
"llvm.cos.f32", "llvm.cos.f64",
"llvm.exp.f32", "llvm.exp.f64",
"llvm.exp2.f32", "llvm.exp2.f64",
"llvm.fabs.f32", "llvm.fabs.f64",
"llvm.floor.f32", "llvm.floor.f64",
"llvm.fma.f32", "llvm.fma.f64",
"llvm.log.f32", "llvm.log.f64",
"llvm.log10.f32", "llvm.log10.f64",
"llvm.nearbyint.f32", "llvm.nearbyint.f64",
"llvm.pow.f32", "llvm.pow.f64",
"llvm.powi.f32", "llvm.powi.f64",
"llvm.rint.f32", "llvm.rint.f64",
"llvm.round.f32", "llvm.round.f64",
"llvm.sin.f32", "llvm.sin.f64",
"llvm.sqrt.f32", "llvm.sqrt.f64",
"llvm.trunc.f32", "llvm.trunc.f64",
};
static bool isIntrinsicInline(Function *F) {
return std::binary_search(std::begin(IntrinsicInline),
std::end(IntrinsicInline), F->getName());
}
//
// Returns of float, double and complex need to be handled with a helper
// function.
//
static bool fixupFPReturnAndCall(Function &F, Module *M,
const MipsTargetMachine &TM) {
bool Modified = false;
LLVMContext &C = M->getContext();
Type *MyVoid = Type::getVoidTy(C);
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end();
I != E; ++I) {
Instruction &Inst = *I;
if (const ReturnInst *RI = dyn_cast<ReturnInst>(I)) {
Value *RVal = RI->getReturnValue();
if (!RVal) continue;
//
// If there is a return value and it needs a helper function,
// figure out which one and add a call before the actual
// return to this helper. The purpose of the helper is to move
// floating point values from their soft float return mapping to
// where they would have been mapped to in floating point registers.
//
Type *T = RVal->getType();
FPReturnVariant RV = whichFPReturnVariant(T);
if (RV == NoFPRet) continue;
static const char* Helper[NoFPRet] = {
"__mips16_ret_sf", "__mips16_ret_df", "__mips16_ret_sc",
"__mips16_ret_dc"
};
const char *Name = Helper[RV];
AttributeSet A;
Value *Params[] = {RVal};
Modified = true;
//
// These helper functions have a different calling ABI so
// this __Mips16RetHelper indicates that so that later
// during call setup, the proper call lowering to the helper
// functions will take place.
//
A = A.addAttribute(C, AttributeSet::FunctionIndex,
"__Mips16RetHelper");
A = A.addAttribute(C, AttributeSet::FunctionIndex,
Attribute::ReadNone);
A = A.addAttribute(C, AttributeSet::FunctionIndex,
Attribute::NoInline);
Value *F = (M->getOrInsertFunction(Name, A, MyVoid, T, nullptr));
CallInst::Create(F, Params, "", &Inst );
} else if (const CallInst *CI = dyn_cast<CallInst>(I)) {
const Value* V = CI->getCalledValue();
const Type* T = nullptr;
if (V) T = V->getType();
const PointerType *PFT=nullptr;
if (T) PFT = dyn_cast<PointerType>(T);
const FunctionType *FT=nullptr;
if (PFT) FT = dyn_cast<FunctionType>(PFT->getElementType());
Function *F_ = CI->getCalledFunction();
if (FT && needsFPReturnHelper(*FT) &&
!(F_ && isIntrinsicInline(F_))) {
Modified=true;
F.addFnAttr("saveS2");
}
if (F_ && !isIntrinsicInline(F_)) {
// pic mode calls are handled by already defined
// helper functions
if (needsFPReturnHelper(*F_)) {
Modified=true;
F.addFnAttr("saveS2");
}
if (TM.getRelocationModel() != Reloc::PIC_ ) {
if (needsFPHelperFromSig(*F_)) {
assureFPCallStub(*F_, M, TM);
Modified=true;
}
}
}
}
}
return Modified;
}
static void createFPFnStub(Function *F, Module *M, FPParamVariant PV,
const MipsTargetMachine &TM) {
bool PicMode = TM.getRelocationModel() == Reloc::PIC_;
bool LE = TM.isLittleEndian();
LLVMContext &Context = M->getContext();
std::string Name = F->getName();
std::string SectionName = ".mips16.fn." + Name;
std::string StubName = "__fn_stub_" + Name;
std::string LocalName = "$$__fn_local_" + Name;
Function *FStub = Function::Create
(F->getFunctionType(),
Function::InternalLinkage, StubName, M);
FStub->addFnAttr("mips16_fp_stub");
FStub->addFnAttr(llvm::Attribute::Naked);
FStub->addFnAttr(llvm::Attribute::NoUnwind);
FStub->addFnAttr(llvm::Attribute::NoInline);
FStub->addFnAttr("nomips16");
FStub->setSection(SectionName);
BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
InlineAsmHelper IAH(Context, BB);
if (PicMode) {
IAH.Out(".set noreorder");
IAH.Out(".cpload $$25");
IAH.Out(".set reorder");
IAH.Out(".reloc 0,R_MIPS_NONE," + Name);
IAH.Out("la $$25," + LocalName);
}
else {
IAH.Out("la $$25," + Name);
}
swapFPIntParams(PV, M, IAH, LE, false);
IAH.Out("jr $$25");
IAH.Out(LocalName + " = " + Name);
new UnreachableInst(FStub->getContext(), BB);
}
//
// remove the use-soft-float attribute
//
static void removeUseSoftFloat(Function &F) {
AttributeSet A;
DEBUG(errs() << "removing -use-soft-float\n");
A = A.addAttribute(F.getContext(), AttributeSet::FunctionIndex,
"use-soft-float", "false");
F.removeAttributes(AttributeSet::FunctionIndex, A);
if (F.hasFnAttribute("use-soft-float")) {
DEBUG(errs() << "still has -use-soft-float\n");
}
F.addAttributes(AttributeSet::FunctionIndex, A);
}
//
// This pass only makes sense when the underlying chip has floating point but
// we are compiling as mips16.
// For all mips16 functions (that are not stubs we have already generated), or
// declared via attributes as nomips16, we must:
// 1) fixup all returns of float, double, single and double complex
// by calling a helper function before the actual return.
// 2) generate helper functions (stubs) that can be called by mips32
// functions that will move parameters passed normally passed in
// floating point
// registers the soft float equivalents.
// 3) in the case of static relocation, generate helper functions so that
// mips16 functions can call extern functions of unknown type (mips16 or
// mips32).
// 4) TBD. For pic, calls to extern functions of unknown type are handled by
// predefined helper functions in libc but this work is currently done
// during call lowering but it should be moved here in the future.
//
bool Mips16HardFloat::runOnModule(Module &M) {
DEBUG(errs() << "Run on Module Mips16HardFloat\n");
bool Modified = false;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->hasFnAttribute("nomips16") &&
F->hasFnAttribute("use-soft-float")) {
removeUseSoftFloat(*F);
continue;
}
if (F->isDeclaration() || F->hasFnAttribute("mips16_fp_stub") ||
F->hasFnAttribute("nomips16")) continue;
Modified |= fixupFPReturnAndCall(*F, &M, TM);
FPParamVariant V = whichFPParamVariantNeeded(*F);
if (V != NoSig) {
Modified = true;
createFPFnStub(F, &M, V, TM);
}
}
return Modified;
}
ModulePass *llvm::createMips16HardFloatPass(MipsTargetMachine &TM) {
return new Mips16HardFloat(TM);
}
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