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/CallSite.h" 16 #include "llvm/IR/Constants.h" 17 #include "llvm/IR/DataLayout.h" 18 #include "llvm/IR/DerivedTypes.h" 19 #include "llvm/IR/IRBuilder.h" 20 #include "llvm/IR/Module.h" 21 #include "llvm/IR/Type.h" 22 #include "llvm/Support/ErrorHandling.h" 23 #include "llvm/Support/raw_ostream.h" 24 using namespace llvm; 25 26 /// This function is used when we want to lower an intrinsic call to a call of 27 /// an external function. This handles hard cases such as when there was already 28 /// a prototype for the external function, but that prototype doesn't match the 29 /// arguments we expect to pass in. 30 template <class ArgIt> 31 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI, 32 ArgIt ArgBegin, ArgIt ArgEnd, 33 Type *RetTy) { 34 // If we haven't already looked up this function, check to see if the 35 // program already contains a function with this name. 36 Module *M = CI->getModule(); 37 // Get or insert the definition now. 38 std::vector<Type *> ParamTys; 39 for (ArgIt I = ArgBegin; I != ArgEnd; ++I) 40 ParamTys.push_back((*I)->getType()); 41 FunctionCallee FCache = 42 M->getOrInsertFunction(NewFn, FunctionType::get(RetTy, ParamTys, false)); 43 44 IRBuilder<> Builder(CI->getParent(), CI->getIterator()); 45 SmallVector<Value *, 8> Args(ArgBegin, ArgEnd); 46 CallInst *NewCI = Builder.CreateCall(FCache, Args); 47 NewCI->setName(CI->getName()); 48 if (!CI->use_empty()) 49 CI->replaceAllUsesWith(NewCI); 50 return NewCI; 51 } 52 53 /// Emit the code to lower bswap of V before the specified instruction IP. 54 static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) { 55 assert(V->getType()->isIntOrIntVectorTy() && "Can't bswap a non-integer type!"); 56 57 unsigned BitSize = V->getType()->getScalarSizeInBits(); 58 59 IRBuilder<> Builder(IP); 60 61 switch(BitSize) { 62 default: llvm_unreachable("Unhandled type size of value to byteswap!"); 63 case 16: { 64 Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8), 65 "bswap.2"); 66 Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8), 67 "bswap.1"); 68 V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16"); 69 break; 70 } 71 case 32: { 72 Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24), 73 "bswap.4"); 74 Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8), 75 "bswap.3"); 76 Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8), 77 "bswap.2"); 78 Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24), 79 "bswap.1"); 80 Tmp3 = Builder.CreateAnd(Tmp3, 81 ConstantInt::get(V->getType(), 0xFF0000), 82 "bswap.and3"); 83 Tmp2 = Builder.CreateAnd(Tmp2, 84 ConstantInt::get(V->getType(), 0xFF00), 85 "bswap.and2"); 86 Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1"); 87 Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2"); 88 V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32"); 89 break; 90 } 91 case 64: { 92 Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56), 93 "bswap.8"); 94 Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40), 95 "bswap.7"); 96 Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24), 97 "bswap.6"); 98 Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8), 99 "bswap.5"); 100 Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8), 101 "bswap.4"); 102 Value* Tmp3 = Builder.CreateLShr(V, 103 ConstantInt::get(V->getType(), 24), 104 "bswap.3"); 105 Value* Tmp2 = Builder.CreateLShr(V, 106 ConstantInt::get(V->getType(), 40), 107 "bswap.2"); 108 Value* Tmp1 = Builder.CreateLShr(V, 109 ConstantInt::get(V->getType(), 56), 110 "bswap.1"); 111 Tmp7 = Builder.CreateAnd(Tmp7, 112 ConstantInt::get(V->getType(), 113 0xFF000000000000ULL), 114 "bswap.and7"); 115 Tmp6 = Builder.CreateAnd(Tmp6, 116 ConstantInt::get(V->getType(), 117 0xFF0000000000ULL), 118 "bswap.and6"); 119 Tmp5 = Builder.CreateAnd(Tmp5, 120 ConstantInt::get(V->getType(), 121 0xFF00000000ULL), 122 "bswap.and5"); 123 Tmp4 = Builder.CreateAnd(Tmp4, 124 ConstantInt::get(V->getType(), 125 0xFF000000ULL), 126 "bswap.and4"); 127 Tmp3 = Builder.CreateAnd(Tmp3, 128 ConstantInt::get(V->getType(), 129 0xFF0000ULL), 130 "bswap.and3"); 131 Tmp2 = Builder.CreateAnd(Tmp2, 132 ConstantInt::get(V->getType(), 133 0xFF00ULL), 134 "bswap.and2"); 135 Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1"); 136 Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2"); 137 Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3"); 138 Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4"); 139 Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5"); 140 Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6"); 141 V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64"); 142 break; 143 } 144 } 145 return V; 146 } 147 148 /// Emit the code to lower ctpop of V before the specified instruction IP. 149 static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) { 150 assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!"); 151 152 static const uint64_t MaskValues[6] = { 153 0x5555555555555555ULL, 0x3333333333333333ULL, 154 0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL, 155 0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL 156 }; 157 158 IRBuilder<> Builder(IP); 159 160 unsigned BitSize = V->getType()->getPrimitiveSizeInBits(); 161 unsigned WordSize = (BitSize + 63) / 64; 162 Value *Count = ConstantInt::get(V->getType(), 0); 163 164 for (unsigned n = 0; n < WordSize; ++n) { 165 Value *PartValue = V; 166 for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize); 167 i <<= 1, ++ct) { 168 Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]); 169 Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1"); 170 Value *VShift = Builder.CreateLShr(PartValue, 171 ConstantInt::get(V->getType(), i), 172 "ctpop.sh"); 173 Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2"); 174 PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step"); 175 } 176 Count = Builder.CreateAdd(PartValue, Count, "ctpop.part"); 177 if (BitSize > 64) { 178 V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64), 179 "ctpop.part.sh"); 180 BitSize -= 64; 181 } 182 } 183 184 return Count; 185 } 186 187 /// Emit the code to lower ctlz of V before the specified instruction IP. 188 static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) { 189 190 IRBuilder<> Builder(IP); 191 192 unsigned BitSize = V->getType()->getPrimitiveSizeInBits(); 193 for (unsigned i = 1; i < BitSize; i <<= 1) { 194 Value *ShVal = ConstantInt::get(V->getType(), i); 195 ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh"); 196 V = Builder.CreateOr(V, ShVal, "ctlz.step"); 197 } 198 199 V = Builder.CreateNot(V); 200 return LowerCTPOP(Context, V, IP); 201 } 202 203 static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname, 204 const char *Dname, 205 const char *LDname) { 206 CallSite CS(CI); 207 switch (CI->getArgOperand(0)->getType()->getTypeID()) { 208 default: llvm_unreachable("Invalid type in intrinsic"); 209 case Type::FloatTyID: 210 ReplaceCallWith(Fname, CI, CS.arg_begin(), CS.arg_end(), 211 Type::getFloatTy(CI->getContext())); 212 break; 213 case Type::DoubleTyID: 214 ReplaceCallWith(Dname, CI, CS.arg_begin(), CS.arg_end(), 215 Type::getDoubleTy(CI->getContext())); 216 break; 217 case Type::X86_FP80TyID: 218 case Type::FP128TyID: 219 case Type::PPC_FP128TyID: 220 ReplaceCallWith(LDname, CI, CS.arg_begin(), CS.arg_end(), 221 CI->getArgOperand(0)->getType()); 222 break; 223 } 224 } 225 226 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) { 227 IRBuilder<> Builder(CI); 228 LLVMContext &Context = CI->getContext(); 229 230 const Function *Callee = CI->getCalledFunction(); 231 assert(Callee && "Cannot lower an indirect call!"); 232 233 CallSite CS(CI); 234 switch (Callee->getIntrinsicID()) { 235 case Intrinsic::not_intrinsic: 236 report_fatal_error("Cannot lower a call to a non-intrinsic function '"+ 237 Callee->getName() + "'!"); 238 default: 239 report_fatal_error("Code generator does not support intrinsic function '"+ 240 Callee->getName()+"'!"); 241 242 case Intrinsic::expect: { 243 // Just replace __builtin_expect(exp, c) with EXP. 244 Value *V = CI->getArgOperand(0); 245 CI->replaceAllUsesWith(V); 246 break; 247 } 248 249 case Intrinsic::ctpop: 250 CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI)); 251 break; 252 253 case Intrinsic::bswap: 254 CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI)); 255 break; 256 257 case Intrinsic::ctlz: 258 CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI)); 259 break; 260 261 case Intrinsic::cttz: { 262 // cttz(x) -> ctpop(~X & (X-1)) 263 Value *Src = CI->getArgOperand(0); 264 Value *NotSrc = Builder.CreateNot(Src); 265 NotSrc->setName(Src->getName() + ".not"); 266 Value *SrcM1 = ConstantInt::get(Src->getType(), 1); 267 SrcM1 = Builder.CreateSub(Src, SrcM1); 268 Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI); 269 CI->replaceAllUsesWith(Src); 270 break; 271 } 272 273 case Intrinsic::stacksave: 274 case Intrinsic::stackrestore: { 275 if (!Warned) 276 errs() << "WARNING: this target does not support the llvm.stack" 277 << (Callee->getIntrinsicID() == Intrinsic::stacksave ? 278 "save" : "restore") << " intrinsic.\n"; 279 Warned = true; 280 if (Callee->getIntrinsicID() == Intrinsic::stacksave) 281 CI->replaceAllUsesWith(Constant::getNullValue(CI->getType())); 282 break; 283 } 284 285 case Intrinsic::get_dynamic_area_offset: 286 errs() << "WARNING: this target does not support the custom llvm.get." 287 "dynamic.area.offset. It is being lowered to a constant 0\n"; 288 // Just lower it to a constant 0 because for most targets 289 // @llvm.get.dynamic.area.offset is lowered to zero. 290 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0)); 291 break; 292 case Intrinsic::returnaddress: 293 case Intrinsic::frameaddress: 294 errs() << "WARNING: this target does not support the llvm." 295 << (Callee->getIntrinsicID() == Intrinsic::returnaddress ? 296 "return" : "frame") << "address intrinsic.\n"; 297 CI->replaceAllUsesWith( 298 ConstantPointerNull::get(cast<PointerType>(CI->getType()))); 299 break; 300 case Intrinsic::addressofreturnaddress: 301 errs() << "WARNING: this target does not support the " 302 "llvm.addressofreturnaddress intrinsic.\n"; 303 CI->replaceAllUsesWith( 304 ConstantPointerNull::get(cast<PointerType>(CI->getType()))); 305 break; 306 307 case Intrinsic::prefetch: 308 break; // Simply strip out prefetches on unsupported architectures 309 310 case Intrinsic::pcmarker: 311 break; // Simply strip out pcmarker on unsupported architectures 312 case Intrinsic::readcyclecounter: { 313 errs() << "WARNING: this target does not support the llvm.readcyclecoun" 314 << "ter intrinsic. It is being lowered to a constant 0\n"; 315 CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0)); 316 break; 317 } 318 319 case Intrinsic::dbg_declare: 320 case Intrinsic::dbg_label: 321 break; // Simply strip out debugging intrinsics 322 323 case Intrinsic::eh_typeid_for: 324 // Return something different to eh_selector. 325 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1)); 326 break; 327 328 case Intrinsic::annotation: 329 case Intrinsic::ptr_annotation: 330 // Just drop the annotation, but forward the value 331 CI->replaceAllUsesWith(CI->getOperand(0)); 332 break; 333 334 case Intrinsic::assume: 335 case Intrinsic::var_annotation: 336 break; // Strip out these intrinsics 337 338 case Intrinsic::memcpy: { 339 Type *IntPtr = DL.getIntPtrType(Context); 340 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr, 341 /* isSigned */ false); 342 Value *Ops[3]; 343 Ops[0] = CI->getArgOperand(0); 344 Ops[1] = CI->getArgOperand(1); 345 Ops[2] = Size; 346 ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 347 break; 348 } 349 case Intrinsic::memmove: { 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("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 358 break; 359 } 360 case Intrinsic::memset: { 361 Value *Op0 = CI->getArgOperand(0); 362 Type *IntPtr = DL.getIntPtrType(Op0->getType()); 363 Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr, 364 /* isSigned */ false); 365 Value *Ops[3]; 366 Ops[0] = Op0; 367 // Extend the amount to i32. 368 Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1), 369 Type::getInt32Ty(Context), 370 /* isSigned */ false); 371 Ops[2] = Size; 372 ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType()); 373 break; 374 } 375 case Intrinsic::sqrt: { 376 ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl"); 377 break; 378 } 379 case Intrinsic::log: { 380 ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl"); 381 break; 382 } 383 case Intrinsic::log2: { 384 ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l"); 385 break; 386 } 387 case Intrinsic::log10: { 388 ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l"); 389 break; 390 } 391 case Intrinsic::exp: { 392 ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl"); 393 break; 394 } 395 case Intrinsic::exp2: { 396 ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l"); 397 break; 398 } 399 case Intrinsic::pow: { 400 ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl"); 401 break; 402 } 403 case Intrinsic::sin: { 404 ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl"); 405 break; 406 } 407 case Intrinsic::cos: { 408 ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl"); 409 break; 410 } 411 case Intrinsic::floor: { 412 ReplaceFPIntrinsicWithCall(CI, "floorf", "floor", "floorl"); 413 break; 414 } 415 case Intrinsic::ceil: { 416 ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill"); 417 break; 418 } 419 case Intrinsic::trunc: { 420 ReplaceFPIntrinsicWithCall(CI, "truncf", "trunc", "truncl"); 421 break; 422 } 423 case Intrinsic::round: { 424 ReplaceFPIntrinsicWithCall(CI, "roundf", "round", "roundl"); 425 break; 426 } 427 case Intrinsic::copysign: { 428 ReplaceFPIntrinsicWithCall(CI, "copysignf", "copysign", "copysignl"); 429 break; 430 } 431 case Intrinsic::flt_rounds: 432 // Lower to "round to the nearest" 433 if (!CI->getType()->isVoidTy()) 434 CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1)); 435 break; 436 case Intrinsic::invariant_start: 437 case Intrinsic::lifetime_start: 438 // Discard region information. 439 CI->replaceAllUsesWith(UndefValue::get(CI->getType())); 440 break; 441 case Intrinsic::invariant_end: 442 case Intrinsic::lifetime_end: 443 // Discard region information. 444 break; 445 } 446 447 assert(CI->use_empty() && 448 "Lowering should have eliminated any uses of the intrinsic call!"); 449 CI->eraseFromParent(); 450 } 451 452 bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) { 453 // Verify this is a simple bswap. 454 if (CI->getNumArgOperands() != 1 || 455 CI->getType() != CI->getArgOperand(0)->getType() || 456 !CI->getType()->isIntegerTy()) 457 return false; 458 459 IntegerType *Ty = dyn_cast<IntegerType>(CI->getType()); 460 if (!Ty) 461 return false; 462 463 // Okay, we can do this xform, do so now. 464 Module *M = CI->getModule(); 465 Function *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty); 466 467 Value *Op = CI->getArgOperand(0); 468 Op = CallInst::Create(Int, Op, CI->getName(), CI); 469 470 CI->replaceAllUsesWith(Op); 471 CI->eraseFromParent(); 472 return true; 473 } 474