lib/CodeGen/IntrinsicLowering.cpp

   1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the IntrinsicLowering class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Constants.h"
  15 #include "llvm/DerivedTypes.h"
  16 #include "llvm/Module.h"
  17 #include "llvm/Type.h"
  18 #include "llvm/CodeGen/IntrinsicLowering.h"
  19 #include "llvm/Support/IRBuilder.h"
  20 #include "llvm/Target/TargetData.h"
  21 #include "llvm/ADT/SmallVector.h"
  22 using namespace llvm;
  23
  24 template <class ArgIt>
  25 static void EnsureFunctionExists(Module &M, const char *Name,
  26                                  ArgIt ArgBegin, ArgIt ArgEnd,
  27                                  const Type *RetTy) {
  28   // Insert a correctly-typed definition now.
  29   std::vector<const Type *> ParamTys;
  30   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  31     ParamTys.push_back(I->getType());
  32   M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
  33 }
  34
  35 static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
  36                                     const char *FName,
  37                                     const char *DName, const char *LDName) {
  38   // Insert definitions for all the floating point types.
  39   switch((int)Fn->arg_begin()->getType()->getTypeID()) {
  40   case Type::FloatTyID:
  41     EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
  42                          Type::FloatTy);
  43     break;
  44   case Type::DoubleTyID:
  45     EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
  46                          Type::DoubleTy);
  47     break;
  48   case Type::X86_FP80TyID:
  49   case Type::FP128TyID:
  50   case Type::PPC_FP128TyID:
  51     EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
  52                          Fn->arg_begin()->getType());
  53     break;
  54   }
  55 }
  56
  57 /// ReplaceCallWith - This function is used when we want to lower an intrinsic
  58 /// call to a call of an external function.  This handles hard cases such as
  59 /// when there was already a prototype for the external function, and if that
  60 /// prototype doesn't match the arguments we expect to pass in.
  61 template <class ArgIt>
  62 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
  63                                  ArgIt ArgBegin, ArgIt ArgEnd,
  64                                  const Type *RetTy, Constant *&FCache) {
  65   if (!FCache) {
  66     // If we haven't already looked up this function, check to see if the
  67     // program already contains a function with this name.
  68     Module *M = CI->getParent()->getParent()->getParent();
  69     // Get or insert the definition now.
  70     std::vector<const Type *> ParamTys;
  71     for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  72       ParamTys.push_back((*I)->getType());
  73     FCache = M->getOrInsertFunction(NewFn,
  74                                     FunctionType::get(RetTy, ParamTys, false));
  75   }
  76
  77   IRBuilder<> Builder(CI->getParent(), CI);
  78   SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
  79   CallInst *NewCI = Builder.CreateCall(FCache, Args.begin(), Args.end());
  80   NewCI->setName(CI->getName());
  81   if (!CI->use_empty())
  82     CI->replaceAllUsesWith(NewCI);
  83   return NewCI;
  84 }
  85
  86 void IntrinsicLowering::AddPrototypes(Module &M) {
  87   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
  88     if (I->isDeclaration() && !I->use_empty())
  89       switch (I->getIntrinsicID()) {
  90       default: break;
  91       case Intrinsic::setjmp:
  92         EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
  93                              Type::Int32Ty);
  94         break;
  95       case Intrinsic::longjmp:
  96         EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
  97                              Type::VoidTy);
  98         break;
  99       case Intrinsic::siglongjmp:
 100         EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
 101                              Type::VoidTy);
 102         break;
 103       case Intrinsic::memcpy:
 104         M.getOrInsertFunction("memcpy", PointerType::getUnqual(Type::Int8Ty),
 105                               PointerType::getUnqual(Type::Int8Ty),
 106                               PointerType::getUnqual(Type::Int8Ty),
 107                               TD.getIntPtrType(), (Type *)0);
 108         break;
 109       case Intrinsic::memmove:
 110         M.getOrInsertFunction("memmove", PointerType::getUnqual(Type::Int8Ty),
 111                               PointerType::getUnqual(Type::Int8Ty),
 112                               PointerType::getUnqual(Type::Int8Ty),
 113                               TD.getIntPtrType(), (Type *)0);
 114         break;
 115       case Intrinsic::memset:
 116         M.getOrInsertFunction("memset", PointerType::getUnqual(Type::Int8Ty),
 117                               PointerType::getUnqual(Type::Int8Ty),
 118                               Type::Int32Ty,
 119                               TD.getIntPtrType(), (Type *)0);
 120         break;
 121       case Intrinsic::sqrt:
 122         EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
 123         break;
 124       case Intrinsic::sin:
 125         EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
 126         break;
 127       case Intrinsic::cos:
 128         EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
 129         break;
 130       case Intrinsic::pow:
 131         EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
 132         break;
 133       case Intrinsic::log:
 134         EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
 135         break;
 136       case Intrinsic::log2:
 137         EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
 138         break;
 139       case Intrinsic::log10:
 140         EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
 141         break;
 142       case Intrinsic::exp:
 143         EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
 144         break;
 145       case Intrinsic::exp2:
 146         EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
 147         break;
 148       }
 149 }
 150
 151 /// LowerBSWAP - Emit the code to lower bswap of V before the specified
 152 /// instruction IP.
 153 static Value *LowerBSWAP(Value *V, Instruction *IP) {
 154   assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
 155
 156   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 157
 158   IRBuilder<> Builder(IP->getParent(), IP);
 159
 160   switch(BitSize) {
 161   default: assert(0 && "Unhandled type size of value to byteswap!");
 162   case 16: {
 163     Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 164                                     "bswap.2");
 165     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 166                                      "bswap.1");
 167     V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
 168     break;
 169   }
 170   case 32: {
 171     Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
 172                                     "bswap.4");
 173     Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 174                                     "bswap.3");
 175     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 176                                      "bswap.2");
 177     Value *Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
 178                                      "bswap.1");
 179     Tmp3 = Builder.CreateAnd(Tmp3, ConstantInt::get(Type::Int32Ty, 0xFF0000),
 180                              "bswap.and3");
 181     Tmp2 = Builder.CreateAnd(Tmp2, ConstantInt::get(Type::Int32Ty, 0xFF00),
 182                              "bswap.and2");
 183     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
 184     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
 185     V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
 186     break;
 187   }
 188   case 64: {
 189     Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
 190                                     "bswap.8");
 191     Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
 192                                     "bswap.7");
 193     Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
 194                                     "bswap.6");
 195     Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
 196                                     "bswap.5");
 197     Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
 198                                      "bswap.4");
 199     Value* Tmp3 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
 200                                      "bswap.3");
 201     Value* Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 40),
 202                                      "bswap.2");
 203     Value* Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 56),
 204                                      "bswap.1");
 205     Tmp7 = Builder.CreateAnd(Tmp7,
 206                              ConstantInt::get(Type::Int64Ty,
 207                                               0xFF000000000000ULL),
 208                              "bswap.and7");
 209     Tmp6 = Builder.CreateAnd(Tmp6,
 210                              ConstantInt::get(Type::Int64Ty,
 211                                               0xFF0000000000ULL),
 212                              "bswap.and6");
 213     Tmp5 = Builder.CreateAnd(Tmp5,
 214                              ConstantInt::get(Type::Int64Ty, 0xFF00000000ULL),
 215                              "bswap.and5");
 216     Tmp4 = Builder.CreateAnd(Tmp4,
 217                              ConstantInt::get(Type::Int64Ty, 0xFF000000ULL),
 218                              "bswap.and4");
 219     Tmp3 = Builder.CreateAnd(Tmp3,
 220                              ConstantInt::get(Type::Int64Ty, 0xFF0000ULL),
 221                              "bswap.and3");
 222     Tmp2 = Builder.CreateAnd(Tmp2,
 223                              ConstantInt::get(Type::Int64Ty, 0xFF00ULL),
 224                              "bswap.and2");
 225     Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
 226     Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
 227     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
 228     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
 229     Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
 230     Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
 231     V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
 232     break;
 233   }
 234   }
 235   return V;
 236 }
 237
 238 /// LowerCTPOP - Emit the code to lower ctpop of V before the specified
 239 /// instruction IP.
 240 static Value *LowerCTPOP(Value *V, Instruction *IP) {
 241   assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
 242
 243   static const uint64_t MaskValues[6] = {
 244     0x5555555555555555ULL, 0x3333333333333333ULL,
 245     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
 246     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
 247   };
 248
 249   IRBuilder<> Builder(IP->getParent(), IP);
 250
 251   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 252   unsigned WordSize = (BitSize + 63) / 64;
 253   Value *Count = ConstantInt::get(V->getType(), 0);
 254
 255   for (unsigned n = 0; n < WordSize; ++n) {
 256     Value *PartValue = V;
 257     for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
 258          i <<= 1, ++ct) {
 259       Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
 260       Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
 261       Value *VShift = Builder.CreateLShr(PartValue,
 262                                          ConstantInt::get(V->getType(), i),
 263                                          "ctpop.sh");
 264       Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
 265       PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
 266     }
 267     Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
 268     if (BitSize > 64) {
 269       V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
 270                              "ctpop.part.sh");
 271       BitSize -= 64;
 272     }
 273   }
 274
 275   return Count;
 276 }
 277
 278 /// LowerCTLZ - Emit the code to lower ctlz of V before the specified
 279 /// instruction IP.
 280 static Value *LowerCTLZ(Value *V, Instruction *IP) {
 281
 282   IRBuilder<> Builder(IP->getParent(), IP);
 283
 284   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 285   for (unsigned i = 1; i < BitSize; i <<= 1) {
 286     Value *ShVal = ConstantInt::get(V->getType(), i);
 287     ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
 288     V = Builder.CreateOr(V, ShVal, "ctlz.step");
 289   }
 290
 291   V = Builder.CreateNot(V);
 292   return LowerCTPOP(V, IP);
 293 }
 294
 295 /// Convert the llvm.part.select.iX.iY intrinsic. This intrinsic takes
 296 /// three integer arguments. The first argument is the Value from which the
 297 /// bits will be selected. It may be of any bit width. The second and third
 298 /// arguments specify a range of bits to select with the second argument
 299 /// specifying the low bit and the third argument specifying the high bit. Both
 300 /// must be type i32. The result is the corresponding selected bits from the
 301 /// Value in the same width as the Value (first argument). If the low bit index
 302 /// is higher than the high bit index then the inverse selection is done and
 303 /// the bits are returned in inverse order.
 304 /// @brief Lowering of llvm.part.select intrinsic.
 305 static Instruction *LowerPartSelect(CallInst *CI) {
 306   IRBuilder<> Builder;
 307
 308   // Make sure we're dealing with a part select intrinsic here
 309   Function *F = CI->getCalledFunction();
 310   const FunctionType *FT = F->getFunctionType();
 311   if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
 312       FT->getNumParams() != 3 || !FT->getParamType(0)->isInteger() ||
 313       !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger())
 314     return CI;
 315
 316   // Get the intrinsic implementation function by converting all the . to _
 317   // in the intrinsic's function name and then reconstructing the function
 318   // declaration.
 319   std::string Name(F->getName());
 320   for (unsigned i = 4; i < Name.length(); ++i)
 321     if (Name[i] == '.')
 322       Name[i] = '_';
 323   Module* M = F->getParent();
 324   F = cast<Function>(M->getOrInsertFunction(Name, FT));
 325   F->setLinkage(GlobalValue::WeakAnyLinkage);
 326
 327   // If we haven't defined the impl function yet, do so now
 328   if (F->isDeclaration()) {
 329
 330     // Get the arguments to the function
 331     Function::arg_iterator args = F->arg_begin();
 332     Value* Val = args++; Val->setName("Val");
 333     Value* Lo = args++; Lo->setName("Lo");
 334     Value* Hi = args++; Hi->setName("High");
 335
 336     // We want to select a range of bits here such that [Hi, Lo] is shifted
 337     // down to the low bits. However, it is quite possible that Hi is smaller
 338     // than Lo in which case the bits have to be reversed.
 339
 340     // Create the blocks we will need for the two cases (forward, reverse)
 341     BasicBlock* CurBB   = BasicBlock::Create("entry", F);
 342     BasicBlock *RevSize = BasicBlock::Create("revsize", CurBB->getParent());
 343     BasicBlock *FwdSize = BasicBlock::Create("fwdsize", CurBB->getParent());
 344     BasicBlock *Compute = BasicBlock::Create("compute", CurBB->getParent());
 345     BasicBlock *Reverse = BasicBlock::Create("reverse", CurBB->getParent());
 346     BasicBlock *RsltBlk = BasicBlock::Create("result",  CurBB->getParent());
 347
 348     Builder.SetInsertPoint(CurBB);
 349
 350     // Cast Hi and Lo to the size of Val so the widths are all the same
 351     if (Hi->getType() != Val->getType())
 352       Hi = Builder.CreateIntCast(Hi, Val->getType(), /* isSigned */ false,
 353                                  "tmp");
 354     if (Lo->getType() != Val->getType())
 355       Lo = Builder.CreateIntCast(Lo, Val->getType(), /* isSigned */ false,
 356                                  "tmp");
 357
 358     // Compute a few things that both cases will need, up front.
 359     Constant* Zero = ConstantInt::get(Val->getType(), 0);
 360     Constant* One = ConstantInt::get(Val->getType(), 1);
 361     Constant* AllOnes = ConstantInt::getAllOnesValue(Val->getType());
 362
 363     // Compare the Hi and Lo bit positions. This is used to determine
 364     // which case we have (forward or reverse)
 365     Value *Cmp = Builder.CreateICmpULT(Hi, Lo, "less");
 366     Builder.CreateCondBr(Cmp, RevSize, FwdSize);
 367
 368     // First, compute the number of bits in the forward case.
 369     Builder.SetInsertPoint(FwdSize);
 370     Value* FBitSize = Builder.CreateSub(Hi, Lo, "fbits");
 371     Builder.CreateBr(Compute);
 372
 373     // Second, compute the number of bits in the reverse case.
 374     Builder.SetInsertPoint(RevSize);
 375     Value* RBitSize = Builder.CreateSub(Lo, Hi, "rbits");
 376     Builder.CreateBr(Compute);
 377
 378     // Now, compute the bit range. Start by getting the bitsize and the shift
 379     // amount (either Hi or Lo) from PHI nodes. Then we compute a mask for
 380     // the number of bits we want in the range. We shift the bits down to the
 381     // least significant bits, apply the mask to zero out unwanted high bits,
 382     // and we have computed the "forward" result. It may still need to be
 383     // reversed.
 384     Builder.SetInsertPoint(Compute);
 385
 386     // Get the BitSize from one of the two subtractions
 387     PHINode *BitSize = Builder.CreatePHI(Val->getType(), "bits");
 388     BitSize->reserveOperandSpace(2);
 389     BitSize->addIncoming(FBitSize, FwdSize);
 390     BitSize->addIncoming(RBitSize, RevSize);
 391
 392     // Get the ShiftAmount as the smaller of Hi/Lo
 393     PHINode *ShiftAmt = Builder.CreatePHI(Val->getType(), "shiftamt");
 394     ShiftAmt->reserveOperandSpace(2);
 395     ShiftAmt->addIncoming(Lo, FwdSize);
 396     ShiftAmt->addIncoming(Hi, RevSize);
 397
 398     // Increment the bit size
 399     Value *BitSizePlusOne = Builder.CreateAdd(BitSize, One, "bits");
 400
 401     // Create a Mask to zero out the high order bits.
 402     Value* Mask = Builder.CreateShl(AllOnes, BitSizePlusOne, "mask");
 403     Mask = Builder.CreateNot(Mask, "mask");
 404
 405     // Shift the bits down and apply the mask
 406     Value* FRes = Builder.CreateLShr(Val, ShiftAmt, "fres");
 407     FRes = Builder.CreateAnd(FRes, Mask, "fres");
 408     Builder.CreateCondBr(Cmp, Reverse, RsltBlk);
 409
 410     // In the Reverse block we have the mask already in FRes but we must reverse
 411     // it by shifting FRes bits right and putting them in RRes by shifting them
 412     // in from left.
 413     Builder.SetInsertPoint(Reverse);
 414
 415     // First set up our loop counters
 416     PHINode *Count = Builder.CreatePHI(Val->getType(), "count");
 417     Count->reserveOperandSpace(2);
 418     Count->addIncoming(BitSizePlusOne, Compute);
 419
 420     // Next, get the value that we are shifting.
 421     PHINode *BitsToShift = Builder.CreatePHI(Val->getType(), "val");
 422     BitsToShift->reserveOperandSpace(2);
 423     BitsToShift->addIncoming(FRes, Compute);
 424
 425     // Finally, get the result of the last computation
 426     PHINode *RRes = Builder.CreatePHI(Val->getType(), "rres");
 427     RRes->reserveOperandSpace(2);
 428     RRes->addIncoming(Zero, Compute);
 429
 430     // Decrement the counter
 431     Value *Decr = Builder.CreateSub(Count, One, "decr");
 432     Count->addIncoming(Decr, Reverse);
 433
 434     // Compute the Bit that we want to move
 435     Value *Bit = Builder.CreateAnd(BitsToShift, One, "bit");
 436
 437     // Compute the new value for next iteration.
 438     Value *NewVal = Builder.CreateLShr(BitsToShift, One, "rshift");
 439     BitsToShift->addIncoming(NewVal, Reverse);
 440
 441     // Shift the bit into the low bits of the result.
 442     Value *NewRes = Builder.CreateShl(RRes, One, "lshift");
 443     NewRes = Builder.CreateOr(NewRes, Bit, "addbit");
 444     RRes->addIncoming(NewRes, Reverse);
 445
 446     // Terminate loop if we've moved all the bits.
 447     Value *Cond = Builder.CreateICmpEQ(Decr, Zero, "cond");
 448     Builder.CreateCondBr(Cond, RsltBlk, Reverse);
 449
 450     // Finally, in the result block, select one of the two results with a PHI
 451     // node and return the result;
 452     Builder.SetInsertPoint(RsltBlk);
 453     PHINode *BitSelect = Builder.CreatePHI(Val->getType(), "part_select");
 454     BitSelect->reserveOperandSpace(2);
 455     BitSelect->addIncoming(FRes, Compute);
 456     BitSelect->addIncoming(NewRes, Reverse);
 457     Builder.CreateRet(BitSelect);
 458   }
 459
 460   // Return a call to the implementation function
 461   Builder.SetInsertPoint(CI->getParent(), CI);
 462   CallInst *NewCI = Builder.CreateCall3(F, CI->getOperand(1),
 463                                         CI->getOperand(2), CI->getOperand(3));
 464   NewCI->setName(CI->getName());
 465   return NewCI;
 466 }
 467
 468 /// Convert the llvm.part.set.iX.iY.iZ intrinsic. This intrinsic takes
 469 /// four integer arguments (iAny %Value, iAny %Replacement, i32 %Low, i32 %High)
 470 /// The first two arguments can be any bit width. The result is the same width
 471 /// as %Value. The operation replaces bits between %Low and %High with the value
 472 /// in %Replacement. If %Replacement is not the same width, it is truncated or
 473 /// zero extended as appropriate to fit the bits being replaced. If %Low is
 474 /// greater than %High then the inverse set of bits are replaced.
 475 /// @brief Lowering of llvm.bit.part.set intrinsic.
 476 static Instruction *LowerPartSet(CallInst *CI) {
 477   IRBuilder<> Builder;
 478
 479   // Make sure we're dealing with a part select intrinsic here
 480   Function *F = CI->getCalledFunction();
 481   const FunctionType *FT = F->getFunctionType();
 482   if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
 483       FT->getNumParams() != 4 || !FT->getParamType(0)->isInteger() ||
 484       !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger() ||
 485       !FT->getParamType(3)->isInteger())
 486     return CI;
 487
 488   // Get the intrinsic implementation function by converting all the . to _
 489   // in the intrinsic's function name and then reconstructing the function
 490   // declaration.
 491   std::string Name(F->getName());
 492   for (unsigned i = 4; i < Name.length(); ++i)
 493     if (Name[i] == '.')
 494       Name[i] = '_';
 495   Module* M = F->getParent();
 496   F = cast<Function>(M->getOrInsertFunction(Name, FT));
 497   F->setLinkage(GlobalValue::WeakAnyLinkage);
 498
 499   // If we haven't defined the impl function yet, do so now
 500   if (F->isDeclaration()) {
 501     // Get the arguments for the function.
 502     Function::arg_iterator args = F->arg_begin();
 503     Value* Val = args++; Val->setName("Val");
 504     Value* Rep = args++; Rep->setName("Rep");
 505     Value* Lo  = args++; Lo->setName("Lo");
 506     Value* Hi  = args++; Hi->setName("Hi");
 507
 508     // Get some types we need
 509     const IntegerType* ValTy = cast<IntegerType>(Val->getType());
 510     const IntegerType* RepTy = cast<IntegerType>(Rep->getType());
 511     uint32_t RepBits = RepTy->getBitWidth();
 512
 513     // Constant Definitions
 514     ConstantInt* RepBitWidth = ConstantInt::get(Type::Int32Ty, RepBits);
 515     ConstantInt* RepMask = ConstantInt::getAllOnesValue(RepTy);
 516     ConstantInt* ValMask = ConstantInt::getAllOnesValue(ValTy);
 517     ConstantInt* One = ConstantInt::get(Type::Int32Ty, 1);
 518     ConstantInt* ValOne = ConstantInt::get(ValTy, 1);
 519     ConstantInt* Zero = ConstantInt::get(Type::Int32Ty, 0);
 520     ConstantInt* ValZero = ConstantInt::get(ValTy, 0);
 521
 522     // Basic blocks we fill in below.
 523     BasicBlock* entry = BasicBlock::Create("entry", F, 0);
 524     BasicBlock* large = BasicBlock::Create("large", F, 0);
 525     BasicBlock* small = BasicBlock::Create("small", F, 0);
 526     BasicBlock* reverse = BasicBlock::Create("reverse", F, 0);
 527     BasicBlock* result = BasicBlock::Create("result", F, 0);
 528
 529     // BASIC BLOCK: entry
 530     Builder.SetInsertPoint(entry);
 531     // First, get the number of bits that we're placing as an i32
 532     Value* is_forward = Builder.CreateICmpULT(Lo, Hi);
 533     Value* Hi_pn = Builder.CreateSelect(is_forward, Hi, Lo);
 534     Value* Lo_pn = Builder.CreateSelect(is_forward, Lo, Hi);
 535     Value* NumBits = Builder.CreateSub(Hi_pn, Lo_pn);
 536     NumBits = Builder.CreateAdd(NumBits, One);
 537     // Now, convert Lo and Hi to ValTy bit width
 538     Lo = Builder.CreateIntCast(Lo_pn, ValTy, /* isSigned */ false);
 539     // Determine if the replacement bits are larger than the number of bits we
 540     // are replacing and deal with it.
 541     Value* is_large = Builder.CreateICmpULT(NumBits, RepBitWidth);
 542     Builder.CreateCondBr(is_large, large, small);
 543
 544     // BASIC BLOCK: large
 545     Builder.SetInsertPoint(large);
 546     Value* MaskBits = Builder.CreateSub(RepBitWidth, NumBits);
 547     MaskBits = Builder.CreateIntCast(MaskBits, RepMask->getType(),
 548                                      /* isSigned */ false);
 549     Value* Mask1 = Builder.CreateLShr(RepMask, MaskBits);
 550     Value* Rep2 = Builder.CreateAnd(Mask1, Rep);
 551     Builder.CreateBr(small);
 552
 553     // BASIC BLOCK: small
 554     Builder.SetInsertPoint(small);
 555     PHINode* Rep3 = Builder.CreatePHI(RepTy);
 556     Rep3->reserveOperandSpace(2);
 557     Rep3->addIncoming(Rep2, large);
 558     Rep3->addIncoming(Rep, entry);
 559     Value* Rep4 = Builder.CreateIntCast(Rep3, ValTy, /* isSigned */ false);
 560     Builder.CreateCondBr(is_forward, result, reverse);
 561
 562     // BASIC BLOCK: reverse (reverses the bits of the replacement)
 563     Builder.SetInsertPoint(reverse);
 564     // Set up our loop counter as a PHI so we can decrement on each iteration.
 565     // We will loop for the number of bits in the replacement value.
 566     PHINode *Count = Builder.CreatePHI(Type::Int32Ty, "count");
 567     Count->reserveOperandSpace(2);
 568     Count->addIncoming(NumBits, small);
 569
 570     // Get the value that we are shifting bits out of as a PHI because
 571     // we'll change this with each iteration.
 572     PHINode *BitsToShift = Builder.CreatePHI(Val->getType(), "val");
 573     BitsToShift->reserveOperandSpace(2);
 574     BitsToShift->addIncoming(Rep4, small);
 575
 576     // Get the result of the last computation or zero on first iteration
 577     PHINode *RRes = Builder.CreatePHI(Val->getType(), "rres");
 578     RRes->reserveOperandSpace(2);
 579     RRes->addIncoming(ValZero, small);
 580
 581     // Decrement the loop counter by one
 582     Value *Decr = Builder.CreateSub(Count, One);
 583     Count->addIncoming(Decr, reverse);
 584
 585     // Get the bit that we want to move into the result
 586     Value *Bit = Builder.CreateAnd(BitsToShift, ValOne);
 587
 588     // Compute the new value of the bits to shift for the next iteration.
 589     Value *NewVal = Builder.CreateLShr(BitsToShift, ValOne);
 590     BitsToShift->addIncoming(NewVal, reverse);
 591
 592     // Shift the bit we extracted into the low bit of the result.
 593     Value *NewRes = Builder.CreateShl(RRes, ValOne);
 594     NewRes = Builder.CreateOr(NewRes, Bit);
 595     RRes->addIncoming(NewRes, reverse);
 596
 597     // Terminate loop if we've moved all the bits.
 598     Value *Cond = Builder.CreateICmpEQ(Decr, Zero);
 599     Builder.CreateCondBr(Cond, result, reverse);
 600
 601     // BASIC BLOCK: result
 602     Builder.SetInsertPoint(result);
 603     PHINode *Rplcmnt = Builder.CreatePHI(Val->getType());
 604     Rplcmnt->reserveOperandSpace(2);
 605     Rplcmnt->addIncoming(NewRes, reverse);
 606     Rplcmnt->addIncoming(Rep4, small);
 607     Value* t0   = Builder.CreateIntCast(NumBits, ValTy, /* isSigned */ false);
 608     Value* t1   = Builder.CreateShl(ValMask, Lo);
 609     Value* t2   = Builder.CreateNot(t1);
 610     Value* t3   = Builder.CreateShl(t1, t0);
 611     Value* t4   = Builder.CreateOr(t2, t3);
 612     Value* t5   = Builder.CreateAnd(t4, Val);
 613     Value* t6   = Builder.CreateShl(Rplcmnt, Lo);
 614     Value* Rslt = Builder.CreateOr(t5, t6, "part_set");
 615     Builder.CreateRet(Rslt);
 616   }
 617
 618   // Return a call to the implementation function
 619   Builder.SetInsertPoint(CI->getParent(), CI);
 620   CallInst *NewCI = Builder.CreateCall4(F, CI->getOperand(1),
 621                                         CI->getOperand(2), CI->getOperand(3),
 622                                         CI->getOperand(4));
 623   NewCI->setName(CI->getName());
 624   return NewCI;
 625 }
 626
 627 static void ReplaceFPIntrinsicWithCall(CallInst *CI, Constant *FCache,
 628                                        Constant *DCache, Constant *LDCache,
 629                                        const char *Fname, const char *Dname,
 630                                        const char *LDname) {
 631   switch (CI->getOperand(1)->getType()->getTypeID()) {
 632   default: assert(0 && "Invalid type in intrinsic"); abort();
 633   case Type::FloatTyID:
 634     ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
 635                   Type::FloatTy, FCache);
 636     break;
 637   case Type::DoubleTyID:
 638     ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
 639                   Type::DoubleTy, DCache);
 640     break;
 641   case Type::X86_FP80TyID:
 642   case Type::FP128TyID:
 643   case Type::PPC_FP128TyID:
 644     ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
 645                   CI->getOperand(1)->getType(), LDCache);
 646     break;
 647   }
 648 }
 649
 650 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
 651   IRBuilder<> Builder(CI->getParent(), CI);
 652
 653   Function *Callee = CI->getCalledFunction();
 654   assert(Callee && "Cannot lower an indirect call!");
 655
 656   switch (Callee->getIntrinsicID()) {
 657   case Intrinsic::not_intrinsic:
 658     cerr << "Cannot lower a call to a non-intrinsic function '"
 659          << Callee->getName() << "'!\n";
 660     abort();
 661   default:
 662     cerr << "Error: Code generator does not support intrinsic function '"
 663          << Callee->getName() << "'!\n";
 664     abort();
 665
 666     // The setjmp/longjmp intrinsics should only exist in the code if it was
 667     // never optimized (ie, right out of the CFE), or if it has been hacked on
 668     // by the lowerinvoke pass.  In both cases, the right thing to do is to
 669     // convert the call to an explicit setjmp or longjmp call.
 670   case Intrinsic::setjmp: {
 671     static Constant *SetjmpFCache = 0;
 672     Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
 673                                Type::Int32Ty, SetjmpFCache);
 674     if (CI->getType() != Type::VoidTy)
 675       CI->replaceAllUsesWith(V);
 676     break;
 677   }
 678   case Intrinsic::sigsetjmp:
 679      if (CI->getType() != Type::VoidTy)
 680        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 681      break;
 682
 683   case Intrinsic::longjmp: {
 684     static Constant *LongjmpFCache = 0;
 685     ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
 686                     Type::VoidTy, LongjmpFCache);
 687     break;
 688   }
 689
 690   case Intrinsic::siglongjmp: {
 691     // Insert the call to abort
 692     static Constant *AbortFCache = 0;
 693     ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
 694                     Type::VoidTy, AbortFCache);
 695     break;
 696   }
 697   case Intrinsic::ctpop:
 698     CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
 699     break;
 700
 701   case Intrinsic::bswap:
 702     CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
 703     break;
 704
 705   case Intrinsic::ctlz:
 706     CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
 707     break;
 708
 709   case Intrinsic::cttz: {
 710     // cttz(x) -> ctpop(~X & (X-1))
 711     Value *Src = CI->getOperand(1);
 712     Value *NotSrc = Builder.CreateNot(Src);
 713     NotSrc->setName(Src->getName() + ".not");
 714     Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
 715     SrcM1 = Builder.CreateSub(Src, SrcM1);
 716     Src = LowerCTPOP(Builder.CreateAnd(NotSrc, SrcM1), CI);
 717     CI->replaceAllUsesWith(Src);
 718     break;
 719   }
 720
 721   case Intrinsic::part_select:
 722     CI->replaceAllUsesWith(LowerPartSelect(CI));
 723     break;
 724
 725   case Intrinsic::part_set:
 726     CI->replaceAllUsesWith(LowerPartSet(CI));
 727     break;
 728
 729   case Intrinsic::stacksave:
 730   case Intrinsic::stackrestore: {
 731     static bool Warned = false;
 732     if (!Warned)
 733       cerr << "WARNING: this target does not support the llvm.stack"
 734            << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
 735                "save" : "restore") << " intrinsic.\n";
 736     Warned = true;
 737     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
 738       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 739     break;
 740   }
 741
 742   case Intrinsic::returnaddress:
 743   case Intrinsic::frameaddress:
 744     cerr << "WARNING: this target does not support the llvm."
 745          << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
 746              "return" : "frame") << "address intrinsic.\n";
 747     CI->replaceAllUsesWith(ConstantPointerNull::get(
 748                                             cast<PointerType>(CI->getType())));
 749     break;
 750
 751   case Intrinsic::prefetch:
 752     break;    // Simply strip out prefetches on unsupported architectures
 753
 754   case Intrinsic::pcmarker:
 755     break;    // Simply strip out pcmarker on unsupported architectures
 756   case Intrinsic::readcyclecounter: {
 757     cerr << "WARNING: this target does not support the llvm.readcyclecoun"
 758          << "ter intrinsic.  It is being lowered to a constant 0\n";
 759     CI->replaceAllUsesWith(ConstantInt::get(Type::Int64Ty, 0));
 760     break;
 761   }
 762
 763   case Intrinsic::dbg_stoppoint:
 764   case Intrinsic::dbg_region_start:
 765   case Intrinsic::dbg_region_end:
 766   case Intrinsic::dbg_func_start:
 767   case Intrinsic::dbg_declare:
 768     break;    // Simply strip out debugging intrinsics
 769
 770   case Intrinsic::eh_exception:
 771   case Intrinsic::eh_selector_i32:
 772   case Intrinsic::eh_selector_i64:
 773     CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 774     break;
 775
 776   case Intrinsic::eh_typeid_for_i32:
 777   case Intrinsic::eh_typeid_for_i64:
 778     // Return something different to eh_selector.
 779     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 780     break;
 781
 782   case Intrinsic::var_annotation:
 783     break;   // Strip out annotate intrinsic
 784
 785   case Intrinsic::memcpy: {
 786     static Constant *MemcpyFCache = 0;
 787     const IntegerType *IntPtr = TD.getIntPtrType();
 788     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 789                                         /* isSigned */ false);
 790     Value *Ops[3];
 791     Ops[0] = CI->getOperand(1);
 792     Ops[1] = CI->getOperand(2);
 793     Ops[2] = Size;
 794     ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
 795                     MemcpyFCache);
 796     break;
 797   }
 798   case Intrinsic::memmove: {
 799     static Constant *MemmoveFCache = 0;
 800     const IntegerType *IntPtr = TD.getIntPtrType();
 801     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 802                                         /* isSigned */ false);
 803     Value *Ops[3];
 804     Ops[0] = CI->getOperand(1);
 805     Ops[1] = CI->getOperand(2);
 806     Ops[2] = Size;
 807     ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
 808                     MemmoveFCache);
 809     break;
 810   }
 811   case Intrinsic::memset: {
 812     static Constant *MemsetFCache = 0;
 813     const IntegerType *IntPtr = TD.getIntPtrType();
 814     Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
 815                                         /* isSigned */ false);
 816     Value *Ops[3];
 817     Ops[0] = CI->getOperand(1);
 818     // Extend the amount to i32.
 819     Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::Int32Ty,
 820                                    /* isSigned */ false);
 821     Ops[2] = Size;
 822     ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType(),
 823                     MemsetFCache);
 824     break;
 825   }
 826   case Intrinsic::sqrt: {
 827     static Constant *sqrtFCache = 0;
 828     static Constant *sqrtDCache = 0;
 829     static Constant *sqrtLDCache = 0;
 830     ReplaceFPIntrinsicWithCall(CI, sqrtFCache, sqrtDCache, sqrtLDCache,
 831                                "sqrtf", "sqrt", "sqrtl");
 832     break;
 833   }
 834   case Intrinsic::log: {
 835     static Constant *logFCache = 0;
 836     static Constant *logDCache = 0;
 837     static Constant *logLDCache = 0;
 838     ReplaceFPIntrinsicWithCall(CI, logFCache, logDCache, logLDCache,
 839                                "logf", "log", "logl");
 840     break;
 841   }
 842   case Intrinsic::log2: {
 843     static Constant *log2FCache = 0;
 844     static Constant *log2DCache = 0;
 845     static Constant *log2LDCache = 0;
 846     ReplaceFPIntrinsicWithCall(CI, log2FCache, log2DCache, log2LDCache,
 847                                "log2f", "log2", "log2l");
 848     break;
 849   }
 850   case Intrinsic::log10: {
 851     static Constant *log10FCache = 0;
 852     static Constant *log10DCache = 0;
 853     static Constant *log10LDCache = 0;
 854     ReplaceFPIntrinsicWithCall(CI, log10FCache, log10DCache, log10LDCache,
 855                                "log10f", "log10", "log10l");
 856     break;
 857   }
 858   case Intrinsic::exp: {
 859     static Constant *expFCache = 0;
 860     static Constant *expDCache = 0;
 861     static Constant *expLDCache = 0;
 862     ReplaceFPIntrinsicWithCall(CI, expFCache, expDCache, expLDCache,
 863                                "expf", "exp", "expl");
 864     break;
 865   }
 866   case Intrinsic::exp2: {
 867     static Constant *exp2FCache = 0;
 868     static Constant *exp2DCache = 0;
 869     static Constant *exp2LDCache = 0;
 870     ReplaceFPIntrinsicWithCall(CI, exp2FCache, exp2DCache, exp2LDCache,
 871                                "exp2f", "exp2", "exp2l");
 872     break;
 873   }
 874   case Intrinsic::pow: {
 875     static Constant *powFCache = 0;
 876     static Constant *powDCache = 0;
 877     static Constant *powLDCache = 0;
 878     ReplaceFPIntrinsicWithCall(CI, powFCache, powDCache, powLDCache,
 879                                "powf", "pow", "powl");
 880     break;
 881   }
 882   case Intrinsic::flt_rounds:
 883      // Lower to "round to the nearest"
 884      if (CI->getType() != Type::VoidTy)
 885        CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
 886      break;
 887   }
 888
 889   assert(CI->use_empty() &&
 890          "Lowering should have eliminated any uses of the intrinsic call!");
 891   CI->eraseFromParent();
 892 }