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-exception 6 // 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" 23 using namespace llvm; 24 25 /// This function is used when we want to lower an intrinsic call to a call of 26 /// an external function. This handles hard cases such as when there was already 27 /// a prototype for the external function, but that prototype doesn't match the 28 /// arguments we expect to pass in. 29 template <class ArgIt> 30 static 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 the 34 // 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. 53 static 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. 148 static 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, 0x00000000FFFFFFFFULL 155 }; 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. 187 static 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 } 201 202 static 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 } 223 224 void 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 // Just replace __builtin_expect(exp, c) with EXP. 241 Value *V = CI->getArgOperand(0); 242 CI->replaceAllUsesWith(V); 243 break; 244 } 245 246 case Intrinsic::ctpop: 247 CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI)); 248 break; 249 250 case Intrinsic::bswap: 251 CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI)); 252 break; 253 254 case Intrinsic::ctlz: 255 CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI)); 256 break; 257 258 case Intrinsic::cttz: { 259 // cttz(x) -> ctpop(~X & (X-1)) 260 Value *Src = CI->getArgOperand(0); 261 Value *NotSrc = Builder.CreateNot(Src); 262 NotSrc->setName(Src->getName() + ".not"); 263 Value *SrcM1 = ConstantInt::get(Src->getType(), 1); 264 SrcM1 = Builder.CreateSub(Src, SrcM1); 265 Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI); 266 CI->replaceAllUsesWith(Src); 267 break; 268 } 269 270 case Intrinsic::stacksave: 271 case Intrinsic::stackrestore: { 272 if (!Warned) 273 errs() << "WARNING: this target does not support the llvm.stack" 274 << (Callee->getIntrinsicID() == Intrinsic::stacksave ? 275 "save" : "restore") << " intrinsic.\n"; 276 Warned = true; 277 if (Callee->getIntrinsicID() == Intrinsic::stacksave) 278 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType())); 279 break; 280 } 281 282 case Intrinsic::get_dynamic_area_offset: 283 errs() << "WARNING: this target does not support the custom llvm.get." 284 "dynamic.area.offset. It is being lowered to a constant 0\n"; 285 // Just lower it to a constant 0 because for most targets 286 // @llvm.get.dynamic.area.offset is lowered to zero. 287 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0)); 288 break; 289 case Intrinsic::returnaddress: 290 case Intrinsic::frameaddress: 291 errs() << "WARNING: this target does not support the llvm." 292 << (Callee->getIntrinsicID() == Intrinsic::returnaddress ? 293 "return" : "frame") << "address intrinsic.\n"; 294 CI->replaceAllUsesWith( 295 ConstantPointerNull::get(cast<PointerType>(CI->getType()))); 296 break; 297 case Intrinsic::addressofreturnaddress: 298 errs() << "WARNING: this target does not support the " 299 "llvm.addressofreturnaddress intrinsic.\n"; 300 CI->replaceAllUsesWith( 301 ConstantPointerNull::get(cast<PointerType>(CI->getType()))); 302 break; 303 304 case Intrinsic::prefetch: 305 break; // Simply strip out prefetches on unsupported architectures 306 307 case Intrinsic::pcmarker: 308 break; // Simply strip out pcmarker on unsupported architectures 309 case Intrinsic::readcyclecounter: { 310 errs() << "WARNING: this target does not support the llvm.readcyclecoun" 311 << "ter intrinsic. It is being lowered to a constant 0\n"; 312 CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0)); 313 break; 314 } 315 316 case Intrinsic::dbg_declare: 317 case Intrinsic::dbg_label: 318 break; // Simply strip out debugging intrinsics 319 320 case Intrinsic::eh_typeid_for: 321 // Return something different to eh_selector. 322 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1)); 323 break; 324 325 case Intrinsic::annotation: 326 case Intrinsic::ptr_annotation: 327 // Just drop the annotation, but forward the value 328 CI->replaceAllUsesWith(CI->getOperand(0)); 329 break; 330 331 case Intrinsic::assume: 332 case Intrinsic::experimental_noalias_scope_decl: 333 case Intrinsic::var_annotation: 334 break; // Strip out these intrinsics 335 336 case Intrinsic::memcpy: { 337 Type *IntPtr = DL.getIntPtrType(Context); 338 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr, 339 /* isSigned */ false); 340 Value *Ops[3]; 341 Ops[0] = CI->getArgOperand(0); 342 Ops[1] = CI->getArgOperand(1); 343 Ops[2] = Size; 344 ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 345 break; 346 } 347 case Intrinsic::memmove: { 348 Type *IntPtr = DL.getIntPtrType(Context); 349 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr, 350 /* isSigned */ false); 351 Value *Ops[3]; 352 Ops[0] = CI->getArgOperand(0); 353 Ops[1] = CI->getArgOperand(1); 354 Ops[2] = Size; 355 ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 356 break; 357 } 358 case Intrinsic::memset: { 359 Value *Op0 = CI->getArgOperand(0); 360 Type *IntPtr = DL.getIntPtrType(Op0->getType()); 361 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr, 362 /* isSigned */ false); 363 Value *Ops[3]; 364 Ops[0] = Op0; 365 // Extend the amount to i32. 366 Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1), 367 Type::getInt32Ty(Context), 368 /* isSigned */ false); 369 Ops[2] = Size; 370 ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 371 break; 372 } 373 case Intrinsic::sqrt: { 374 ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl"); 375 break; 376 } 377 case Intrinsic::log: { 378 ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl"); 379 break; 380 } 381 case Intrinsic::log2: { 382 ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l"); 383 break; 384 } 385 case Intrinsic::log10: { 386 ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l"); 387 break; 388 } 389 case Intrinsic::exp: { 390 ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl"); 391 break; 392 } 393 case Intrinsic::exp2: { 394 ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l"); 395 break; 396 } 397 case Intrinsic::pow: { 398 ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl"); 399 break; 400 } 401 case Intrinsic::sin: { 402 ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl"); 403 break; 404 } 405 case Intrinsic::cos: { 406 ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl"); 407 break; 408 } 409 case Intrinsic::floor: { 410 ReplaceFPIntrinsicWithCall(CI, "floorf", "floor", "floorl"); 411 break; 412 } 413 case Intrinsic::ceil: { 414 ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill"); 415 break; 416 } 417 case Intrinsic::trunc: { 418 ReplaceFPIntrinsicWithCall(CI, "truncf", "trunc", "truncl"); 419 break; 420 } 421 case Intrinsic::round: { 422 ReplaceFPIntrinsicWithCall(CI, "roundf", "round", "roundl"); 423 break; 424 } 425 case Intrinsic::roundeven: { 426 ReplaceFPIntrinsicWithCall(CI, "roundevenf", "roundeven", "roundevenl"); 427 break; 428 } 429 case Intrinsic::copysign: { 430 ReplaceFPIntrinsicWithCall(CI, "copysignf", "copysign", "copysignl"); 431 break; 432 } 433 case Intrinsic::flt_rounds: 434 // Lower to "round to the nearest" 435 if (!CI->getType()->isVoidTy()) 436 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1)); 437 break; 438 case Intrinsic::invariant_start: 439 case Intrinsic::lifetime_start: 440 // Discard region information. 441 CI->replaceAllUsesWith(UndefValue::get(CI->getType())); 442 break; 443 case Intrinsic::invariant_end: 444 case Intrinsic::lifetime_end: 445 // Discard region information. 446 break; 447 } 448 449 assert(CI->use_empty() && 450 "Lowering should have eliminated any uses of the intrinsic call!"); 451 CI->eraseFromParent(); 452 } 453 454 bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) { 455 // Verify this is a simple bswap. 456 if (CI->arg_size() != 1 || CI->getType() != CI->getArgOperand(0)->getType() || 457 !CI->getType()->isIntegerTy()) 458 return false; 459 460 IntegerType *Ty = dyn_cast<IntegerType>(CI->getType()); 461 if (!Ty) 462 return false; 463 464 // Okay, we can do this xform, do so now. 465 Module *M = CI->getModule(); 466 Function *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty); 467 468 Value *Op = CI->getArgOperand(0); 469 Op = CallInst::Create(Int, Op, CI->getName(), CI); 470 471 CI->replaceAllUsesWith(Op); 472 CI->eraseFromParent(); 473 return true; 474 } 475