532 lines · cpp
1//===- Mips16HardFloat.cpp for Mips16 Hard Float --------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This file defines a pass needed for Mips16 Hard Float10//11//===----------------------------------------------------------------------===//12 13#include "MipsTargetMachine.h"14#include "llvm/CodeGen/TargetPassConfig.h"15#include "llvm/IR/Module.h"16#include "llvm/IR/Value.h"17#include "llvm/Support/Debug.h"18#include "llvm/Support/ModRef.h"19#include "llvm/Support/raw_ostream.h"20#include <string>21 22using namespace llvm;23 24#define DEBUG_TYPE "mips16-hard-float"25 26namespace {27 28 class Mips16HardFloat : public ModulePass {29 public:30 static char ID;31 32 Mips16HardFloat() : ModulePass(ID) {}33 34 StringRef getPassName() const override { return "MIPS16 Hard Float Pass"; }35 36 void getAnalysisUsage(AnalysisUsage &AU) const override {37 AU.addRequired<TargetPassConfig>();38 ModulePass::getAnalysisUsage(AU);39 }40 41 bool runOnModule(Module &M) override;42 };43 44} // end anonymous namespace45 46static void emitInlineAsm(LLVMContext &C, BasicBlock *BB, StringRef AsmText) {47 std::vector<Type *> AsmArgTypes;48 std::vector<Value *> AsmArgs;49 50 FunctionType *AsmFTy =51 FunctionType::get(Type::getVoidTy(C), AsmArgTypes, false);52 InlineAsm *IA = InlineAsm::get(AsmFTy, AsmText, "", true,53 /* IsAlignStack */ false, InlineAsm::AD_ATT);54 CallInst::Create(IA, AsmArgs, "", BB);55}56 57char Mips16HardFloat::ID = 0;58 59//60// Return types that matter for hard float are:61// float, double, complex float, and complex double62//63enum FPReturnVariant {64 FRet, DRet, CFRet, CDRet, NoFPRet65};66 67//68// Determine which FP return type this function has69//70static FPReturnVariant whichFPReturnVariant(Type *T) {71 switch (T->getTypeID()) {72 case Type::FloatTyID:73 return FRet;74 case Type::DoubleTyID:75 return DRet;76 case Type::StructTyID: {77 StructType *ST = cast<StructType>(T);78 if (ST->getNumElements() != 2)79 break;80 if ((ST->getElementType(0)->isFloatTy()) &&81 (ST->getElementType(1)->isFloatTy()))82 return CFRet;83 if ((ST->getElementType(0)->isDoubleTy()) &&84 (ST->getElementType(1)->isDoubleTy()))85 return CDRet;86 break;87 }88 default:89 break;90 }91 return NoFPRet;92}93 94// Parameter type that matter are float, (float, float), (float, double),95// double, (double, double), (double, float)96enum FPParamVariant {97 FSig, FFSig, FDSig,98 DSig, DDSig, DFSig, NoSig99};100 101// which floating point parameter signature variant we are dealing with102using TypeID = Type::TypeID;103const Type::TypeID FloatTyID = Type::FloatTyID;104const Type::TypeID DoubleTyID = Type::DoubleTyID;105 106static FPParamVariant whichFPParamVariantNeeded(Function &F) {107 switch (F.arg_size()) {108 case 0:109 return NoSig;110 case 1:{111 TypeID ArgTypeID = F.getFunctionType()->getParamType(0)->getTypeID();112 switch (ArgTypeID) {113 case FloatTyID:114 return FSig;115 case DoubleTyID:116 return DSig;117 default:118 return NoSig;119 }120 }121 default: {122 TypeID ArgTypeID0 = F.getFunctionType()->getParamType(0)->getTypeID();123 TypeID ArgTypeID1 = F.getFunctionType()->getParamType(1)->getTypeID();124 switch(ArgTypeID0) {125 case FloatTyID: {126 switch (ArgTypeID1) {127 case FloatTyID:128 return FFSig;129 case DoubleTyID:130 return FDSig;131 default:132 return FSig;133 }134 }135 case DoubleTyID: {136 switch (ArgTypeID1) {137 case FloatTyID:138 return DFSig;139 case DoubleTyID:140 return DDSig;141 default:142 return DSig;143 }144 }145 default:146 return NoSig;147 }148 }149 }150 llvm_unreachable("can't get here");151}152 153// Figure out if we need float point based on the function parameters.154// We need to move variables in and/or out of floating point155// registers because of the ABI156static bool needsFPStubFromParams(Function &F) {157 if (F.arg_size() >=1) {158 Type *ArgType = F.getFunctionType()->getParamType(0);159 switch (ArgType->getTypeID()) {160 case Type::FloatTyID:161 case Type::DoubleTyID:162 return true;163 default:164 break;165 }166 }167 return false;168}169 170static bool needsFPReturnHelper(Function &F) {171 Type* RetType = F.getReturnType();172 return whichFPReturnVariant(RetType) != NoFPRet;173}174 175static bool needsFPReturnHelper(FunctionType &FT) {176 Type* RetType = FT.getReturnType();177 return whichFPReturnVariant(RetType) != NoFPRet;178}179 180static bool needsFPHelperFromSig(Function &F) {181 return needsFPStubFromParams(F) || needsFPReturnHelper(F);182}183 184// We swap between FP and Integer registers to allow Mips16 and Mips32 to185// interoperate186static std::string swapFPIntParams(FPParamVariant PV, Module *M, bool LE,187 bool ToFP) {188 std::string MI = ToFP ? "mtc1 ": "mfc1 ";189 std::string AsmText;190 191 switch (PV) {192 case FSig:193 AsmText += MI + "$$4, $$f12\n";194 break;195 196 case FFSig:197 AsmText += MI + "$$4, $$f12\n";198 AsmText += MI + "$$5, $$f14\n";199 break;200 201 case FDSig:202 AsmText += MI + "$$4, $$f12\n";203 if (LE) {204 AsmText += MI + "$$6, $$f14\n";205 AsmText += MI + "$$7, $$f15\n";206 } else {207 AsmText += MI + "$$7, $$f14\n";208 AsmText += MI + "$$6, $$f15\n";209 }210 break;211 212 case DSig:213 if (LE) {214 AsmText += MI + "$$4, $$f12\n";215 AsmText += MI + "$$5, $$f13\n";216 } else {217 AsmText += MI + "$$5, $$f12\n";218 AsmText += MI + "$$4, $$f13\n";219 }220 break;221 222 case DDSig:223 if (LE) {224 AsmText += MI + "$$4, $$f12\n";225 AsmText += MI + "$$5, $$f13\n";226 AsmText += MI + "$$6, $$f14\n";227 AsmText += MI + "$$7, $$f15\n";228 } else {229 AsmText += MI + "$$5, $$f12\n";230 AsmText += MI + "$$4, $$f13\n";231 AsmText += MI + "$$7, $$f14\n";232 AsmText += MI + "$$6, $$f15\n";233 }234 break;235 236 case DFSig:237 if (LE) {238 AsmText += MI + "$$4, $$f12\n";239 AsmText += MI + "$$5, $$f13\n";240 } else {241 AsmText += MI + "$$5, $$f12\n";242 AsmText += MI + "$$4, $$f13\n";243 }244 AsmText += MI + "$$6, $$f14\n";245 break;246 247 case NoSig:248 break;249 }250 251 return AsmText;252}253 254// Make sure that we know we already need a stub for this function.255// Having called needsFPHelperFromSig256static void assureFPCallStub(Function &F, Module *M,257 const MipsTargetMachine &TM) {258 // for now we only need them for static relocation259 if (TM.isPositionIndependent())260 return;261 LLVMContext &Context = M->getContext();262 bool LE = TM.isLittleEndian();263 std::string Name(F.getName());264 std::string SectionName = ".mips16.call.fp." + Name;265 std::string StubName = "__call_stub_fp_" + Name;266 //267 // see if we already have the stub268 //269 Function *FStub = M->getFunction(StubName);270 if (FStub && !FStub->isDeclaration()) return;271 FStub = Function::Create(F.getFunctionType(),272 Function::InternalLinkage, StubName, M);273 FStub->addFnAttr("mips16_fp_stub");274 FStub->addFnAttr(Attribute::Naked);275 FStub->addFnAttr(Attribute::NoInline);276 FStub->addFnAttr(Attribute::NoUnwind);277 FStub->addFnAttr("nomips16");278 FStub->setSection(SectionName);279 BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);280 FPReturnVariant RV = whichFPReturnVariant(FStub->getReturnType());281 FPParamVariant PV = whichFPParamVariantNeeded(F);282 283 std::string AsmText;284 AsmText += ".set reorder\n";285 AsmText += swapFPIntParams(PV, M, LE, true);286 if (RV != NoFPRet) {287 AsmText += "move $$18, $$31\n";288 AsmText += "jal " + Name + "\n";289 } else {290 AsmText += "lui $$25, %hi(" + Name + ")\n";291 AsmText += "addiu $$25, $$25, %lo(" + Name + ")\n";292 }293 294 switch (RV) {295 case FRet:296 AsmText += "mfc1 $$2, $$f0\n";297 break;298 299 case DRet:300 if (LE) {301 AsmText += "mfc1 $$2, $$f0\n";302 AsmText += "mfc1 $$3, $$f1\n";303 } else {304 AsmText += "mfc1 $$3, $$f0\n";305 AsmText += "mfc1 $$2, $$f1\n";306 }307 break;308 309 case CFRet:310 if (LE) {311 AsmText += "mfc1 $$2, $$f0\n";312 AsmText += "mfc1 $$3, $$f2\n";313 } else {314 AsmText += "mfc1 $$3, $$f0\n";315 AsmText += "mfc1 $$3, $$f2\n";316 }317 break;318 319 case CDRet:320 if (LE) {321 AsmText += "mfc1 $$4, $$f2\n";322 AsmText += "mfc1 $$5, $$f3\n";323 AsmText += "mfc1 $$2, $$f0\n";324 AsmText += "mfc1 $$3, $$f1\n";325 326 } else {327 AsmText += "mfc1 $$5, $$f2\n";328 AsmText += "mfc1 $$4, $$f3\n";329 AsmText += "mfc1 $$3, $$f0\n";330 AsmText += "mfc1 $$2, $$f1\n";331 }332 break;333 334 case NoFPRet:335 break;336 }337 338 if (RV != NoFPRet)339 AsmText += "jr $$18\n";340 else341 AsmText += "jr $$25\n";342 emitInlineAsm(Context, BB, AsmText);343 344 new UnreachableInst(Context, BB);345}346 347// Functions that are llvm intrinsics and don't need helpers.348static const char *const IntrinsicInline[] = {349 "fabs", "fabsf",350 "llvm.ceil.f32", "llvm.ceil.f64",351 "llvm.copysign.f32", "llvm.copysign.f64",352 "llvm.cos.f32", "llvm.cos.f64",353 "llvm.exp.f32", "llvm.exp.f64",354 "llvm.exp2.f32", "llvm.exp2.f64",355 "llvm.fabs.f32", "llvm.fabs.f64",356 "llvm.floor.f32", "llvm.floor.f64",357 "llvm.fma.f32", "llvm.fma.f64",358 "llvm.log.f32", "llvm.log.f64",359 "llvm.log10.f32", "llvm.log10.f64",360 "llvm.nearbyint.f32", "llvm.nearbyint.f64",361 "llvm.pow.f32", "llvm.pow.f64",362 "llvm.powi.f32.i32", "llvm.powi.f64.i32",363 "llvm.rint.f32", "llvm.rint.f64",364 "llvm.round.f32", "llvm.round.f64",365 "llvm.sin.f32", "llvm.sin.f64",366 "llvm.sqrt.f32", "llvm.sqrt.f64",367 "llvm.trunc.f32", "llvm.trunc.f64",368};369 370static bool isIntrinsicInline(Function *F) {371 return llvm::binary_search(IntrinsicInline, F->getName());372}373 374// Returns of float, double and complex need to be handled with a helper375// function.376static bool fixupFPReturnAndCall(Function &F, Module *M,377 const MipsTargetMachine &TM) {378 bool Modified = false;379 LLVMContext &C = M->getContext();380 Type *MyVoid = Type::getVoidTy(C);381 for (auto &BB: F)382 for (auto &I: BB) {383 if (const ReturnInst *RI = dyn_cast<ReturnInst>(&I)) {384 Value *RVal = RI->getReturnValue();385 if (!RVal) continue;386 //387 // If there is a return value and it needs a helper function,388 // figure out which one and add a call before the actual389 // return to this helper. The purpose of the helper is to move390 // floating point values from their soft float return mapping to391 // where they would have been mapped to in floating point registers.392 //393 Type *T = RVal->getType();394 FPReturnVariant RV = whichFPReturnVariant(T);395 if (RV == NoFPRet) continue;396 static const char *const Helper[NoFPRet] = {397 "__mips16_ret_sf", "__mips16_ret_df", "__mips16_ret_sc",398 "__mips16_ret_dc"399 };400 const char *Name = Helper[RV];401 AttributeList A;402 Value *Params[] = {RVal};403 Modified = true;404 //405 // These helper functions have a different calling ABI so406 // this __Mips16RetHelper indicates that so that later407 // during call setup, the proper call lowering to the helper408 // functions will take place.409 //410 A = A.addFnAttribute(C, "__Mips16RetHelper");411 A = A.addFnAttribute(412 C, Attribute::getWithMemoryEffects(C, MemoryEffects::none()));413 A = A.addFnAttribute(C, Attribute::NoInline);414 FunctionCallee F = (M->getOrInsertFunction(Name, A, MyVoid, T));415 CallInst::Create(F, Params, "", I.getIterator());416 } else if (const CallInst *CI = dyn_cast<CallInst>(&I)) {417 FunctionType *FT = CI->getFunctionType();418 Function *F_ = CI->getCalledFunction();419 if (needsFPReturnHelper(*FT) &&420 !(F_ && isIntrinsicInline(F_))) {421 Modified=true;422 F.addFnAttr("saveS2");423 }424 if (F_ && !isIntrinsicInline(F_)) {425 // pic mode calls are handled by already defined426 // helper functions427 if (needsFPReturnHelper(*F_)) {428 Modified=true;429 F.addFnAttr("saveS2");430 }431 if (!TM.isPositionIndependent()) {432 if (needsFPHelperFromSig(*F_)) {433 assureFPCallStub(*F_, M, TM);434 Modified=true;435 }436 }437 }438 }439 }440 return Modified;441}442 443static void createFPFnStub(Function *F, Module *M, FPParamVariant PV,444 const MipsTargetMachine &TM) {445 bool PicMode = TM.isPositionIndependent();446 bool LE = TM.isLittleEndian();447 LLVMContext &Context = M->getContext();448 std::string Name(F->getName());449 std::string SectionName = ".mips16.fn." + Name;450 std::string StubName = "__fn_stub_" + Name;451 std::string LocalName = "$$__fn_local_" + Name;452 Function *FStub = Function::Create453 (F->getFunctionType(),454 Function::InternalLinkage, StubName, M);455 FStub->addFnAttr("mips16_fp_stub");456 FStub->addFnAttr(Attribute::Naked);457 FStub->addFnAttr(Attribute::NoUnwind);458 FStub->addFnAttr(Attribute::NoInline);459 FStub->addFnAttr("nomips16");460 FStub->setSection(SectionName);461 BasicBlock *BB = BasicBlock::Create(Context, "entry", FStub);462 463 std::string AsmText;464 if (PicMode) {465 AsmText += ".set noreorder\n";466 AsmText += ".cpload $$25\n";467 AsmText += ".set reorder\n";468 AsmText += ".reloc 0, R_MIPS_NONE, " + Name + "\n";469 AsmText += "la $$25, " + LocalName + "\n";470 } else471 AsmText += "la $$25, " + Name + "\n";472 AsmText += swapFPIntParams(PV, M, LE, false);473 AsmText += "jr $$25\n";474 AsmText += LocalName + " = " + Name + "\n";475 emitInlineAsm(Context, BB, AsmText);476 477 new UnreachableInst(FStub->getContext(), BB);478}479 480// remove the use-soft-float attribute481static void removeUseSoftFloat(Function &F) {482 LLVM_DEBUG(errs() << "removing -use-soft-float\n");483 F.removeFnAttr("use-soft-float");484 if (F.hasFnAttribute("use-soft-float")) {485 LLVM_DEBUG(errs() << "still has -use-soft-float\n");486 }487 F.addFnAttr("use-soft-float", "false");488}489 490// This pass only makes sense when the underlying chip has floating point but491// we are compiling as mips16.492// For all mips16 functions (that are not stubs we have already generated), or493// declared via attributes as nomips16, we must:494// 1) fixup all returns of float, double, single and double complex495// by calling a helper function before the actual return.496// 2) generate helper functions (stubs) that can be called by mips32497// functions that will move parameters passed normally passed in498// floating point499// registers the soft float equivalents.500// 3) in the case of static relocation, generate helper functions so that501// mips16 functions can call extern functions of unknown type (mips16 or502// mips32).503// 4) TBD. For pic, calls to extern functions of unknown type are handled by504// predefined helper functions in libc but this work is currently done505// during call lowering but it should be moved here in the future.506bool Mips16HardFloat::runOnModule(Module &M) {507 auto &TM = static_cast<const MipsTargetMachine &>(508 getAnalysis<TargetPassConfig>().getTM<TargetMachine>());509 LLVM_DEBUG(errs() << "Run on Module Mips16HardFloat\n");510 bool Modified = false;511 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {512 if (F->hasFnAttribute("nomips16") &&513 F->hasFnAttribute("use-soft-float")) {514 removeUseSoftFloat(*F);515 continue;516 }517 if (F->isDeclaration() || F->hasFnAttribute("mips16_fp_stub") ||518 F->hasFnAttribute("nomips16")) continue;519 Modified |= fixupFPReturnAndCall(*F, &M, TM);520 FPParamVariant V = whichFPParamVariantNeeded(*F);521 if (V != NoSig) {522 Modified = true;523 createFPFnStub(&*F, &M, V, TM);524 }525 }526 return Modified;527}528 529ModulePass *llvm::createMips16HardFloatPass() {530 return new Mips16HardFloat();531}532