488 lines · cpp
1//===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//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 implements the IntrinsicLowering class.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/CodeGen/IntrinsicLowering.h"14#include "llvm/ADT/SmallVector.h"15#include "llvm/IR/Constants.h"16#include "llvm/IR/DataLayout.h"17#include "llvm/IR/DerivedTypes.h"18#include "llvm/IR/IRBuilder.h"19#include "llvm/IR/Module.h"20#include "llvm/IR/Type.h"21#include "llvm/Support/ErrorHandling.h"22#include "llvm/Support/raw_ostream.h"23using namespace llvm;24 25/// This function is used when we want to lower an intrinsic call to a call of26/// an external function. This handles hard cases such as when there was already27/// a prototype for the external function, but that prototype doesn't match the28/// arguments we expect to pass in.29template <class ArgIt>30static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,31 ArgIt ArgBegin, ArgIt ArgEnd,32 Type *RetTy) {33 // If we haven't already looked up this function, check to see if the34 // program already contains a function with this name.35 Module *M = CI->getModule();36 // Get or insert the definition now.37 std::vector<Type *> ParamTys;38 for (ArgIt I = ArgBegin; I != ArgEnd; ++I)39 ParamTys.push_back((*I)->getType());40 FunctionCallee FCache =41 M->getOrInsertFunction(NewFn, FunctionType::get(RetTy, ParamTys, false));42 43 IRBuilder<> Builder(CI->getParent(), CI->getIterator());44 SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);45 CallInst *NewCI = Builder.CreateCall(FCache, Args);46 NewCI->setName(CI->getName());47 if (!CI->use_empty())48 CI->replaceAllUsesWith(NewCI);49 return NewCI;50}51 52/// Emit the code to lower bswap of V before the specified instruction IP.53static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {54 assert(V->getType()->isIntOrIntVectorTy() && "Can't bswap a non-integer type!");55 56 unsigned BitSize = V->getType()->getScalarSizeInBits();57 58 IRBuilder<> Builder(IP);59 60 switch(BitSize) {61 default: llvm_unreachable("Unhandled type size of value to byteswap!");62 case 16: {63 Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),64 "bswap.2");65 Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),66 "bswap.1");67 V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");68 break;69 }70 case 32: {71 Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),72 "bswap.4");73 Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),74 "bswap.3");75 Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),76 "bswap.2");77 Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),78 "bswap.1");79 Tmp3 = Builder.CreateAnd(Tmp3,80 ConstantInt::get(V->getType(), 0xFF0000),81 "bswap.and3");82 Tmp2 = Builder.CreateAnd(Tmp2,83 ConstantInt::get(V->getType(), 0xFF00),84 "bswap.and2");85 Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");86 Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");87 V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");88 break;89 }90 case 64: {91 Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),92 "bswap.8");93 Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),94 "bswap.7");95 Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),96 "bswap.6");97 Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),98 "bswap.5");99 Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),100 "bswap.4");101 Value* Tmp3 = Builder.CreateLShr(V,102 ConstantInt::get(V->getType(), 24),103 "bswap.3");104 Value* Tmp2 = Builder.CreateLShr(V,105 ConstantInt::get(V->getType(), 40),106 "bswap.2");107 Value* Tmp1 = Builder.CreateLShr(V,108 ConstantInt::get(V->getType(), 56),109 "bswap.1");110 Tmp7 = Builder.CreateAnd(Tmp7,111 ConstantInt::get(V->getType(),112 0xFF000000000000ULL),113 "bswap.and7");114 Tmp6 = Builder.CreateAnd(Tmp6,115 ConstantInt::get(V->getType(),116 0xFF0000000000ULL),117 "bswap.and6");118 Tmp5 = Builder.CreateAnd(Tmp5,119 ConstantInt::get(V->getType(),120 0xFF00000000ULL),121 "bswap.and5");122 Tmp4 = Builder.CreateAnd(Tmp4,123 ConstantInt::get(V->getType(),124 0xFF000000ULL),125 "bswap.and4");126 Tmp3 = Builder.CreateAnd(Tmp3,127 ConstantInt::get(V->getType(),128 0xFF0000ULL),129 "bswap.and3");130 Tmp2 = Builder.CreateAnd(Tmp2,131 ConstantInt::get(V->getType(),132 0xFF00ULL),133 "bswap.and2");134 Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");135 Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");136 Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");137 Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");138 Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");139 Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");140 V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");141 break;142 }143 }144 return V;145}146 147/// Emit the code to lower ctpop of V before the specified instruction IP.148static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {149 assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");150 151 static const uint64_t MaskValues[6] = {152 0x5555555555555555ULL, 0x3333333333333333ULL,153 0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,154 0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL155 };156 157 IRBuilder<> Builder(IP);158 159 unsigned BitSize = V->getType()->getPrimitiveSizeInBits();160 unsigned WordSize = (BitSize + 63) / 64;161 Value *Count = ConstantInt::get(V->getType(), 0);162 163 for (unsigned n = 0; n < WordSize; ++n) {164 Value *PartValue = V;165 for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);166 i <<= 1, ++ct) {167 Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);168 Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");169 Value *VShift = Builder.CreateLShr(PartValue,170 ConstantInt::get(V->getType(), i),171 "ctpop.sh");172 Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");173 PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");174 }175 Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");176 if (BitSize > 64) {177 V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),178 "ctpop.part.sh");179 BitSize -= 64;180 }181 }182 183 return Count;184}185 186/// Emit the code to lower ctlz of V before the specified instruction IP.187static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {188 189 IRBuilder<> Builder(IP);190 191 unsigned BitSize = V->getType()->getPrimitiveSizeInBits();192 for (unsigned i = 1; i < BitSize; i <<= 1) {193 Value *ShVal = ConstantInt::get(V->getType(), i);194 ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");195 V = Builder.CreateOr(V, ShVal, "ctlz.step");196 }197 198 V = Builder.CreateNot(V);199 return LowerCTPOP(Context, V, IP);200}201 202static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,203 const char *Dname,204 const char *LDname) {205 switch (CI->getArgOperand(0)->getType()->getTypeID()) {206 default: llvm_unreachable("Invalid type in intrinsic");207 case Type::FloatTyID:208 ReplaceCallWith(Fname, CI, CI->arg_begin(), CI->arg_end(),209 Type::getFloatTy(CI->getContext()));210 break;211 case Type::DoubleTyID:212 ReplaceCallWith(Dname, CI, CI->arg_begin(), CI->arg_end(),213 Type::getDoubleTy(CI->getContext()));214 break;215 case Type::X86_FP80TyID:216 case Type::FP128TyID:217 case Type::PPC_FP128TyID:218 ReplaceCallWith(LDname, CI, CI->arg_begin(), CI->arg_end(),219 CI->getArgOperand(0)->getType());220 break;221 }222}223 224void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {225 IRBuilder<> Builder(CI);226 LLVMContext &Context = CI->getContext();227 228 const Function *Callee = CI->getCalledFunction();229 assert(Callee && "Cannot lower an indirect call!");230 231 switch (Callee->getIntrinsicID()) {232 case Intrinsic::not_intrinsic:233 report_fatal_error("Cannot lower a call to a non-intrinsic function '"+234 Callee->getName() + "'!");235 default:236 report_fatal_error("Code generator does not support intrinsic function '"+237 Callee->getName()+"'!");238 239 case Intrinsic::expect:240 case Intrinsic::expect_with_probability: {241 // Just replace __builtin_expect(exp, c) and242 // __builtin_expect_with_probability(exp, c, p) with EXP.243 Value *V = CI->getArgOperand(0);244 CI->replaceAllUsesWith(V);245 break;246 }247 248 case Intrinsic::allow_runtime_check:249 case Intrinsic::allow_ubsan_check:250 CI->replaceAllUsesWith(ConstantInt::getTrue(CI->getType()));251 return;252 253 case Intrinsic::ctpop:254 CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI));255 break;256 257 case Intrinsic::bswap:258 CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI));259 break;260 261 case Intrinsic::ctlz:262 CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI));263 break;264 265 case Intrinsic::cttz: {266 // cttz(x) -> ctpop(~X & (X-1))267 Value *Src = CI->getArgOperand(0);268 Value *NotSrc = Builder.CreateNot(Src);269 NotSrc->setName(Src->getName() + ".not");270 Value *SrcM1 = ConstantInt::get(Src->getType(), 1);271 SrcM1 = Builder.CreateSub(Src, SrcM1);272 Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);273 CI->replaceAllUsesWith(Src);274 break;275 }276 277 case Intrinsic::stacksave:278 case Intrinsic::stackrestore: {279 if (!Warned)280 errs() << "WARNING: this target does not support the llvm.stack"281 << (Callee->getIntrinsicID() == Intrinsic::stacksave ?282 "save" : "restore") << " intrinsic.\n";283 Warned = true;284 if (Callee->getIntrinsicID() == Intrinsic::stacksave)285 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));286 break;287 }288 289 case Intrinsic::get_dynamic_area_offset:290 errs() << "WARNING: this target does not support the custom llvm.get."291 "dynamic.area.offset. It is being lowered to a constant 0\n";292 // Just lower it to a constant 0 because for most targets293 // @llvm.get.dynamic.area.offset is lowered to zero.294 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0));295 break;296 case Intrinsic::returnaddress:297 case Intrinsic::frameaddress:298 errs() << "WARNING: this target does not support the llvm."299 << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?300 "return" : "frame") << "address intrinsic.\n";301 CI->replaceAllUsesWith(302 ConstantPointerNull::get(cast<PointerType>(CI->getType())));303 break;304 case Intrinsic::addressofreturnaddress:305 errs() << "WARNING: this target does not support the "306 "llvm.addressofreturnaddress intrinsic.\n";307 CI->replaceAllUsesWith(308 ConstantPointerNull::get(cast<PointerType>(CI->getType())));309 break;310 311 case Intrinsic::prefetch:312 break; // Simply strip out prefetches on unsupported architectures313 314 case Intrinsic::pcmarker:315 break; // Simply strip out pcmarker on unsupported architectures316 case Intrinsic::readcyclecounter: {317 errs() << "WARNING: this target does not support the llvm.readcyclecoun"318 << "ter intrinsic. It is being lowered to a constant 0\n";319 CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));320 break;321 }322 case Intrinsic::readsteadycounter: {323 errs() << "WARNING: this target does not support the llvm.readsteadycounter"324 << " intrinsic. It is being lowered to a constant 0\n";325 CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));326 break;327 }328 329 case Intrinsic::dbg_declare:330 case Intrinsic::dbg_label:331 break; // Simply strip out debugging intrinsics332 333 case Intrinsic::eh_typeid_for:334 // Return something different to eh_selector.335 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));336 break;337 338 case Intrinsic::annotation:339 case Intrinsic::ptr_annotation:340 // Just drop the annotation, but forward the value341 CI->replaceAllUsesWith(CI->getOperand(0));342 break;343 344 case Intrinsic::assume:345 case Intrinsic::experimental_noalias_scope_decl:346 case Intrinsic::var_annotation:347 break; // Strip out these intrinsics348 349 case Intrinsic::memcpy: {350 Type *IntPtr = DL.getIntPtrType(Context);351 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,352 /* isSigned */ false);353 Value *Ops[3];354 Ops[0] = CI->getArgOperand(0);355 Ops[1] = CI->getArgOperand(1);356 Ops[2] = Size;357 ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());358 break;359 }360 case Intrinsic::memmove: {361 Type *IntPtr = DL.getIntPtrType(Context);362 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,363 /* isSigned */ false);364 Value *Ops[3];365 Ops[0] = CI->getArgOperand(0);366 Ops[1] = CI->getArgOperand(1);367 Ops[2] = Size;368 ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());369 break;370 }371 case Intrinsic::memset: {372 Value *Op0 = CI->getArgOperand(0);373 Type *IntPtr = DL.getIntPtrType(Op0->getType());374 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,375 /* isSigned */ false);376 Value *Ops[3];377 Ops[0] = Op0;378 // Extend the amount to i32.379 Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1),380 Type::getInt32Ty(Context),381 /* isSigned */ false);382 Ops[2] = Size;383 ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());384 break;385 }386 case Intrinsic::sqrt: {387 ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");388 break;389 }390 case Intrinsic::log: {391 ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");392 break;393 }394 case Intrinsic::log2: {395 ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");396 break;397 }398 case Intrinsic::log10: {399 ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");400 break;401 }402 case Intrinsic::exp: {403 ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");404 break;405 }406 case Intrinsic::exp2: {407 ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");408 break;409 }410 case Intrinsic::pow: {411 ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");412 break;413 }414 case Intrinsic::sin: {415 ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl");416 break;417 }418 case Intrinsic::cos: {419 ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl");420 break;421 }422 case Intrinsic::floor: {423 ReplaceFPIntrinsicWithCall(CI, "floorf", "floor", "floorl");424 break;425 }426 case Intrinsic::ceil: {427 ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill");428 break;429 }430 case Intrinsic::trunc: {431 ReplaceFPIntrinsicWithCall(CI, "truncf", "trunc", "truncl");432 break;433 }434 case Intrinsic::round: {435 ReplaceFPIntrinsicWithCall(CI, "roundf", "round", "roundl");436 break;437 }438 case Intrinsic::roundeven: {439 ReplaceFPIntrinsicWithCall(CI, "roundevenf", "roundeven", "roundevenl");440 break;441 }442 case Intrinsic::copysign: {443 ReplaceFPIntrinsicWithCall(CI, "copysignf", "copysign", "copysignl");444 break;445 }446 case Intrinsic::get_rounding:447 // Lower to "round to the nearest"448 if (!CI->getType()->isVoidTy())449 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));450 break;451 case Intrinsic::invariant_start:452 case Intrinsic::lifetime_start:453 // Discard region information.454 CI->replaceAllUsesWith(PoisonValue::get(CI->getType()));455 break;456 case Intrinsic::invariant_end:457 case Intrinsic::lifetime_end:458 // Discard region information.459 break;460 }461 462 assert(CI->use_empty() &&463 "Lowering should have eliminated any uses of the intrinsic call!");464 CI->eraseFromParent();465}466 467bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) {468 // Verify this is a simple bswap.469 if (CI->arg_size() != 1 || CI->getType() != CI->getArgOperand(0)->getType() ||470 !CI->getType()->isIntegerTy())471 return false;472 473 IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());474 if (!Ty)475 return false;476 477 // Okay, we can do this xform, do so now.478 Module *M = CI->getModule();479 Function *Int = Intrinsic::getOrInsertDeclaration(M, Intrinsic::bswap, Ty);480 481 Value *Op = CI->getArgOperand(0);482 Op = CallInst::Create(Int, Op, CI->getName(), CI->getIterator());483 484 CI->replaceAllUsesWith(Op);485 CI->eraseFromParent();486 return true;487}488