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

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//===- Mips16HardFloat.cpp for Mips16 Hard Float --------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines a pass needed for Mips16 Hard Float
//
//===----------------------------------------------------------------------===//
#include "MipsTargetMachine.h"
#include "llvm/CodeGen/TargetPassConfig.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() : ModulePass(ID) {}
StringRef getPassName() const override { return "MIPS16 Hard Float Pass"; }
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetPassConfig>();
ModulePass::getAnalysisUsage(AU);
}
bool runOnModule(Module &M) override;
};
} // end anonymous namespace
static void emitInlineAsm(LLVMContext &C, BasicBlock *BB, StringRef AsmText) {
std::vector<Type *> AsmArgTypes;
std::vector<Value *> AsmArgs;
FunctionType *AsmFTy =
FunctionType::get(Type::getVoidTy(C), AsmArgTypes, false);
InlineAsm *IA = InlineAsm::get(AsmFTy, AsmText, "", true,
/* IsAlignStack */ false, 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: {
StructType *ST = cast<StructType>(T);
if (ST->getNumElements() != 2)
break;
if ((ST->getElementType(0)->isFloatTy()) &&
(ST->getElementType(1)->isFloatTy()))
return CFRet;
if ((ST->getElementType(0)->isDoubleTy()) &&
(ST->getElementType(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
using TypeID = Type::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(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 std::string swapFPIntParams(FPParamVariant PV, Module *M, bool LE,
bool ToFP) {
std::string MI = ToFP ? "mtc1 ": "mfc1 ";
std::string AsmText;
switch (PV) {
case FSig:
AsmText += MI + "$$4, $$f12\n";
break;
case FFSig:
AsmText += MI + "$$4, $$f12\n";
AsmText += MI + "$$5, $$f14\n";
break;
case FDSig:
AsmText += MI + "$$4, $$f12\n";
if (LE) {
AsmText += MI + "$$6, $$f14\n";
AsmText += MI + "$$7, $$f15\n";
} else {
AsmText += MI + "$$7, $$f14\n";
AsmText += MI + "$$6, $$f15\n";
}
break;
case DSig:
if (LE) {
AsmText += MI + "$$4, $$f12\n";
AsmText += MI + "$$5, $$f13\n";
} else {
AsmText += MI + "$$5, $$f12\n";
AsmText += MI + "$$4, $$f13\n";
}
break;
case DDSig:
if (LE) {
AsmText += MI + "$$4, $$f12\n";
AsmText += MI + "$$5, $$f13\n";
AsmText += MI + "$$6, $$f14\n";
AsmText += MI + "$$7, $$f15\n";
} else {
AsmText += MI + "$$5, $$f12\n";
AsmText += MI + "$$4, $$f13\n";
AsmText += MI + "$$7, $$f14\n";
AsmText += MI + "$$6, $$f15\n";
}
break;
case DFSig:
if (LE) {
AsmText += MI + "$$4, $$f12\n";
AsmText += MI + "$$5, $$f13\n";
} else {
AsmText += MI + "$$5, $$f12\n";
AsmText += MI + "$$4, $$f13\n";
}
AsmText += MI + "$$6, $$f14\n";
break;
case NoSig:
break;
}
return AsmText;
}
// 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.isPositionIndependent())
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(Attribute::Naked);
FStub->addFnAttr(Attribute::NoInline);
FStub->addFnAttr(Attribute::NoUnwind);
FStub->addFnAttr("nomips16");
FStub->setSection(SectionName);
BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
FPReturnVariant RV = whichFPReturnVariant(FStub->getReturnType());
FPParamVariant PV = whichFPParamVariantNeeded(F);
std::string AsmText;
AsmText += ".set reorder\n";
AsmText += swapFPIntParams(PV, M, LE, true);
if (RV != NoFPRet) {
AsmText += "move $$18, $$31\n";
AsmText += "jal " + Name + "\n";
} else {
AsmText += "lui $$25, %hi(" + Name + ")\n";
AsmText += "addiu $$25, $$25, %lo(" + Name + ")\n";
}
switch (RV) {
case FRet:
AsmText += "mfc1 $$2, $$f0\n";
break;
case DRet:
if (LE) {
AsmText += "mfc1 $$2, $$f0\n";
AsmText += "mfc1 $$3, $$f1\n";
} else {
AsmText += "mfc1 $$3, $$f0\n";
AsmText += "mfc1 $$2, $$f1\n";
}
break;
case CFRet:
if (LE) {
AsmText += "mfc1 $$2, $$f0\n";
AsmText += "mfc1 $$3, $$f2\n";
} else {
AsmText += "mfc1 $$3, $$f0\n";
AsmText += "mfc1 $$3, $$f2\n";
}
break;
case CDRet:
if (LE) {
AsmText += "mfc1 $$4, $$f2\n";
AsmText += "mfc1 $$5, $$f3\n";
AsmText += "mfc1 $$2, $$f0\n";
AsmText += "mfc1 $$3, $$f1\n";
} else {
AsmText += "mfc1 $$5, $$f2\n";
AsmText += "mfc1 $$4, $$f3\n";
AsmText += "mfc1 $$3, $$f0\n";
AsmText += "mfc1 $$2, $$f1\n";
}
break;
case NoFPRet:
break;
}
if (RV != NoFPRet)
AsmText += "jr $$18\n";
else
AsmText += "jr $$25\n";
emitInlineAsm(Context, BB, AsmText);
new UnreachableInst(Context, BB);
}
// Functions that are llvm intrinsics and don't need helpers.
static const char *const 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 (auto &BB: F)
for (auto &I: BB) {
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 *const Helper[NoFPRet] = {
"__mips16_ret_sf", "__mips16_ret_df", "__mips16_ret_sc",
"__mips16_ret_dc"
};
const char *Name = Helper[RV];
AttributeList 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, AttributeList::FunctionIndex,
"__Mips16RetHelper");
A = A.addAttribute(C, AttributeList::FunctionIndex,
Attribute::ReadNone);
A = A.addAttribute(C, AttributeList::FunctionIndex,
Attribute::NoInline);
FunctionCallee F = (M->getOrInsertFunction(Name, A, MyVoid, T));
CallInst::Create(F, Params, "", &I);
} else if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
FunctionType *FT = CI->getFunctionType();
Function *F_ = CI->getCalledFunction();
if (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.isPositionIndependent()) {
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.isPositionIndependent();
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(Attribute::Naked);
FStub->addFnAttr(Attribute::NoUnwind);
FStub->addFnAttr(Attribute::NoInline);
FStub->addFnAttr("nomips16");
FStub->setSection(SectionName);
BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);
std::string AsmText;
if (PicMode) {
AsmText += ".set noreorder\n";
AsmText += ".cpload $$25\n";
AsmText += ".set reorder\n";
AsmText += ".reloc 0, R_MIPS_NONE, " + Name + "\n";
AsmText += "la $$25, " + LocalName + "\n";
} else
AsmText += "la $$25, " + Name + "\n";
AsmText += swapFPIntParams(PV, M, LE, false);
AsmText += "jr $$25\n";
AsmText += LocalName + " = " + Name + "\n";
emitInlineAsm(Context, BB, AsmText);
new UnreachableInst(FStub->getContext(), BB);
}
// remove the use-soft-float attribute
static void removeUseSoftFloat(Function &F) {
AttrBuilder B;
LLVM_DEBUG(errs() << "removing -use-soft-float\n");
B.addAttribute("use-soft-float", "false");
F.removeAttributes(AttributeList::FunctionIndex, B);
if (F.hasFnAttribute("use-soft-float")) {
LLVM_DEBUG(errs() << "still has -use-soft-float\n");
}
F.addAttributes(AttributeList::FunctionIndex, B);
}
// 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) {
auto &TM = static_cast<const MipsTargetMachine &>(
getAnalysis<TargetPassConfig>().getTM<TargetMachine>());
LLVM_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() {
return new Mips16HardFloat();
}
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