llvm/lib/CodeGen/IntrinsicLowering.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-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 }