lib/CodeGen/IntrinsicLowering.cpp

   1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the default intrinsic lowering implementation.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/IntrinsicLowering.h"
  15 #include "llvm/Constants.h"
  16 #include "llvm/DerivedTypes.h"
  17 #include "llvm/Module.h"
  18 #include "llvm/Instructions.h"
  19 #include "llvm/Type.h"
  20 #include <iostream>
  21
  22 using namespace llvm;
  23
  24 template <class ArgIt>
  25 static Function *EnsureFunctionExists(Module &M, const char *Name,
  26                                       ArgIt ArgBegin, ArgIt ArgEnd,
  27                                       const Type *RetTy) {
  28   if (Function *F = M.getNamedFunction(Name)) return F;
  29   // It doesn't already exist in the program, insert a new definition now.
  30   std::vector<const Type *> ParamTys;
  31   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  32     ParamTys.push_back(I->getType());
  33   return M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
  34 }
  35
  36 /// ReplaceCallWith - This function is used when we want to lower an intrinsic
  37 /// call to a call of an external function.  This handles hard cases such as
  38 /// when there was already a prototype for the external function, and if that
  39 /// prototype doesn't match the arguments we expect to pass in.
  40 template <class ArgIt>
  41 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
  42                                  ArgIt ArgBegin, ArgIt ArgEnd,
  43                                  const Type *RetTy, Function *&FCache) {
  44   if (!FCache) {
  45     // If we haven't already looked up this function, check to see if the
  46     // program already contains a function with this name.
  47     Module *M = CI->getParent()->getParent()->getParent();
  48     FCache = M->getNamedFunction(NewFn);
  49     if (!FCache) {
  50       // It doesn't already exist in the program, insert a new definition now.
  51       std::vector<const Type *> ParamTys;
  52       for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
  53         ParamTys.push_back((*I)->getType());
  54       FCache = M->getOrInsertFunction(NewFn,
  55                                      FunctionType::get(RetTy, ParamTys, false));
  56     }
  57    }
  58
  59   const FunctionType *FT = FCache->getFunctionType();
  60   std::vector<Value*> Operands;
  61   unsigned ArgNo = 0;
  62   for (ArgIt I = ArgBegin; I != ArgEnd && ArgNo != FT->getNumParams();
  63        ++I, ++ArgNo) {
  64     Value *Arg = *I;
  65     if (Arg->getType() != FT->getParamType(ArgNo))
  66       Arg = new CastInst(Arg, FT->getParamType(ArgNo), Arg->getName(), CI);
  67     Operands.push_back(Arg);
  68   }
  69   // Pass nulls into any additional arguments...
  70   for (; ArgNo != FT->getNumParams(); ++ArgNo)
  71     Operands.push_back(Constant::getNullValue(FT->getParamType(ArgNo)));
  72
  73   std::string Name = CI->getName(); CI->setName("");
  74   if (FT->getReturnType() == Type::VoidTy) Name.clear();
  75   CallInst *NewCI = new CallInst(FCache, Operands, Name, CI);
  76   if (!CI->use_empty()) {
  77     Value *V = NewCI;
  78     if (CI->getType() != NewCI->getType())
  79       V = new CastInst(NewCI, CI->getType(), Name, CI);
  80     CI->replaceAllUsesWith(V);
  81   }
  82   return NewCI;
  83 }
  84
  85 void DefaultIntrinsicLowering::AddPrototypes(Module &M) {
  86   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
  87     if (I->isExternal() && !I->use_empty())
  88       switch (I->getIntrinsicID()) {
  89       default: break;
  90       case Intrinsic::setjmp:
  91         EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
  92                              Type::IntTy);
  93         break;
  94       case Intrinsic::longjmp:
  95         EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
  96                              Type::VoidTy);
  97         break;
  98       case Intrinsic::siglongjmp:
  99         EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
 100                              Type::VoidTy);
 101         break;
 102       case Intrinsic::memcpy:
 103         EnsureFunctionExists(M, "memcpy", I->arg_begin(), --I->arg_end(),
 104                              I->arg_begin()->getType());
 105         break;
 106       case Intrinsic::memmove:
 107         EnsureFunctionExists(M, "memmove", I->arg_begin(), --I->arg_end(),
 108                              I->arg_begin()->getType());
 109         break;
 110       case Intrinsic::memset:
 111         M.getOrInsertFunction("memset", PointerType::get(Type::SByteTy),
 112                               PointerType::get(Type::SByteTy),
 113                               Type::IntTy, (--(--I->arg_end()))->getType(),
 114                               (Type *)0);
 115         break;
 116       case Intrinsic::isunordered_f32:
 117       case Intrinsic::isunordered_f64:
 118         EnsureFunctionExists(M, "isunordered", I->arg_begin(), I->arg_end(),
 119                              Type::BoolTy);
 120         break;
 121       case Intrinsic::sqrt_f32:
 122       case Intrinsic::sqrt_f64:
 123         if(I->arg_begin()->getType() == Type::FloatTy)
 124           EnsureFunctionExists(M, "sqrtf", I->arg_begin(), I->arg_end(),
 125                                Type::FloatTy);
 126         else
 127           EnsureFunctionExists(M, "sqrt", I->arg_begin(), I->arg_end(),
 128                                Type::DoubleTy);
 129         break;
 130       }
 131 }
 132
 133 /// LowerBSWAP - Emit the code to lower bswap of V before the specified
 134 /// instruction IP.
 135 static Value *LowerBSWAP(Value *V, Instruction *IP) {
 136   assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
 137
 138   const Type *DestTy = V->getType();
 139
 140   // Force to unsigned so that the shift rights are logical.
 141   if (DestTy->isSigned())
 142     V = new CastInst(V, DestTy->getUnsignedVersion(), V->getName(), IP);
 143
 144   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 145
 146   switch(BitSize) {
 147   default: assert(0 && "Unhandled type size of value to byteswap!");
 148   case 16: {
 149     Value *Tmp1 = new ShiftInst(Instruction::Shl, V,
 150                                 ConstantInt::get(Type::UByteTy,8),"bswap.2",IP);
 151     Value *Tmp2 = new ShiftInst(Instruction::Shr, V,
 152                                 ConstantInt::get(Type::UByteTy,8),"bswap.1",IP);
 153     V = BinaryOperator::createOr(Tmp1, Tmp2, "bswap.i16", IP);
 154     break;
 155   }
 156   case 32: {
 157     Value *Tmp4 = new ShiftInst(Instruction::Shl, V,
 158                               ConstantInt::get(Type::UByteTy,24),"bswap.4", IP);
 159     Value *Tmp3 = new ShiftInst(Instruction::Shl, V,
 160                                 ConstantInt::get(Type::UByteTy,8),"bswap.3",IP);
 161     Value *Tmp2 = new ShiftInst(Instruction::Shr, V,
 162                                 ConstantInt::get(Type::UByteTy,8),"bswap.2",IP);
 163     Value *Tmp1 = new ShiftInst(Instruction::Shr, V,
 164                               ConstantInt::get(Type::UByteTy,24),"bswap.1", IP);
 165     Tmp3 = BinaryOperator::createAnd(Tmp3,
 166                                      ConstantUInt::get(Type::UIntTy, 0xFF0000),
 167                                      "bswap.and3", IP);
 168     Tmp2 = BinaryOperator::createAnd(Tmp2,
 169                                      ConstantUInt::get(Type::UIntTy, 0xFF00),
 170                                      "bswap.and2", IP);
 171     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or1", IP);
 172     Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or2", IP);
 173     V = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.i32", IP);
 174     break;
 175   }
 176   case 64: {
 177     Value *Tmp8 = new ShiftInst(Instruction::Shl, V,
 178                               ConstantInt::get(Type::UByteTy,56),"bswap.8", IP);
 179     Value *Tmp7 = new ShiftInst(Instruction::Shl, V,
 180                               ConstantInt::get(Type::UByteTy,40),"bswap.7", IP);
 181     Value *Tmp6 = new ShiftInst(Instruction::Shl, V,
 182                               ConstantInt::get(Type::UByteTy,24),"bswap.6", IP);
 183     Value *Tmp5 = new ShiftInst(Instruction::Shl, V,
 184                                 ConstantInt::get(Type::UByteTy,8),"bswap.5",IP);
 185     Value *Tmp4 = new ShiftInst(Instruction::Shr, V,
 186                                 ConstantInt::get(Type::UByteTy,8),"bswap.4",IP);
 187     Value *Tmp3 = new ShiftInst(Instruction::Shr, V,
 188                               ConstantInt::get(Type::UByteTy,24),"bswap.3", IP);
 189     Value *Tmp2 = new ShiftInst(Instruction::Shr, V,
 190                               ConstantInt::get(Type::UByteTy,40),"bswap.2", IP);
 191     Value *Tmp1 = new ShiftInst(Instruction::Shr, V,
 192                               ConstantInt::get(Type::UByteTy,56),"bswap.1", IP);
 193     Tmp7 = BinaryOperator::createAnd(Tmp7,
 194                           ConstantUInt::get(Type::ULongTy, 0xFF000000000000ULL),
 195                           "bswap.and7", IP);
 196     Tmp6 = BinaryOperator::createAnd(Tmp6,
 197                             ConstantUInt::get(Type::ULongTy, 0xFF0000000000ULL),
 198                             "bswap.and6", IP);
 199     Tmp5 = BinaryOperator::createAnd(Tmp5,
 200                               ConstantUInt::get(Type::ULongTy, 0xFF00000000ULL),
 201                               "bswap.and5", IP);
 202     Tmp4 = BinaryOperator::createAnd(Tmp4,
 203                                 ConstantUInt::get(Type::ULongTy, 0xFF000000ULL),
 204                                 "bswap.and4", IP);
 205     Tmp3 = BinaryOperator::createAnd(Tmp3,
 206                                   ConstantUInt::get(Type::ULongTy, 0xFF0000ULL),
 207                                   "bswap.and3", IP);
 208     Tmp2 = BinaryOperator::createAnd(Tmp2,
 209                                     ConstantUInt::get(Type::ULongTy, 0xFF00ULL),
 210                                     "bswap.and2", IP);
 211     Tmp8 = BinaryOperator::createOr(Tmp8, Tmp7, "bswap.or1", IP);
 212     Tmp6 = BinaryOperator::createOr(Tmp6, Tmp5, "bswap.or2", IP);
 213     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or3", IP);
 214     Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or4", IP);
 215     Tmp8 = BinaryOperator::createOr(Tmp8, Tmp6, "bswap.or5", IP);
 216     Tmp4 = BinaryOperator::createOr(Tmp4, Tmp2, "bswap.or6", IP);
 217     V = BinaryOperator::createOr(Tmp8, Tmp4, "bswap.i64", IP);
 218     break;
 219   }
 220   }
 221
 222   if (V->getType() != DestTy)
 223     V = new CastInst(V, DestTy, V->getName(), IP);
 224   return V;
 225 }
 226
 227 /// LowerCTPOP - Emit the code to lower ctpop of V before the specified
 228 /// instruction IP.
 229 static Value *LowerCTPOP(Value *V, Instruction *IP) {
 230   assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
 231
 232   static const uint64_t MaskValues[6] = {
 233     0x5555555555555555ULL, 0x3333333333333333ULL,
 234     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
 235     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
 236   };
 237
 238   const Type *DestTy = V->getType();
 239
 240   // Force to unsigned so that the shift rights are logical.
 241   if (DestTy->isSigned())
 242     V = new CastInst(V, DestTy->getUnsignedVersion(), V->getName(), IP);
 243
 244   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 245   for (unsigned i = 1, ct = 0; i != BitSize; i <<= 1, ++ct) {
 246     Value *MaskCst =
 247       ConstantExpr::getCast(ConstantUInt::get(Type::ULongTy,
 248                                               MaskValues[ct]), V->getType());
 249     Value *LHS = BinaryOperator::createAnd(V, MaskCst, "cppop.and1", IP);
 250     Value *VShift = new ShiftInst(Instruction::Shr, V,
 251                       ConstantInt::get(Type::UByteTy, i), "ctpop.sh", IP);
 252     Value *RHS = BinaryOperator::createAnd(VShift, MaskCst, "cppop.and2", IP);
 253     V = BinaryOperator::createAdd(LHS, RHS, "ctpop.step", IP);
 254   }
 255
 256   if (V->getType() != DestTy)
 257     V = new CastInst(V, DestTy, V->getName(), IP);
 258   return V;
 259 }
 260
 261 /// LowerCTLZ - Emit the code to lower ctlz of V before the specified
 262 /// instruction IP.
 263 static Value *LowerCTLZ(Value *V, Instruction *IP) {
 264   const Type *DestTy = V->getType();
 265
 266   // Force to unsigned so that the shift rights are logical.
 267   if (DestTy->isSigned())
 268     V = new CastInst(V, DestTy->getUnsignedVersion(), V->getName(), IP);
 269
 270   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
 271   for (unsigned i = 1; i != BitSize; i <<= 1) {
 272     Value *ShVal = ConstantInt::get(Type::UByteTy, i);
 273     ShVal = new ShiftInst(Instruction::Shr, V, ShVal, "ctlz.sh", IP);
 274     V = BinaryOperator::createOr(V, ShVal, "ctlz.step", IP);
 275   }
 276
 277   if (V->getType() != DestTy)
 278     V = new CastInst(V, DestTy, V->getName(), IP);
 279
 280   V = BinaryOperator::createNot(V, "", IP);
 281   return LowerCTPOP(V, IP);
 282 }
 283
 284
 285
 286 void DefaultIntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
 287   Function *Callee = CI->getCalledFunction();
 288   assert(Callee && "Cannot lower an indirect call!");
 289
 290   switch (Callee->getIntrinsicID()) {
 291   case Intrinsic::not_intrinsic:
 292     std::cerr << "Cannot lower a call to a non-intrinsic function '"
 293               << Callee->getName() << "'!\n";
 294     abort();
 295   default:
 296     std::cerr << "Error: Code generator does not support intrinsic function '"
 297               << Callee->getName() << "'!\n";
 298     abort();
 299
 300     // The setjmp/longjmp intrinsics should only exist in the code if it was
 301     // never optimized (ie, right out of the CFE), or if it has been hacked on
 302     // by the lowerinvoke pass.  In both cases, the right thing to do is to
 303     // convert the call to an explicit setjmp or longjmp call.
 304   case Intrinsic::setjmp: {
 305     static Function *SetjmpFCache = 0;
 306     Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin()+1, CI->op_end(),
 307                                Type::IntTy, SetjmpFCache);
 308     if (CI->getType() != Type::VoidTy)
 309       CI->replaceAllUsesWith(V);
 310     break;
 311   }
 312   case Intrinsic::sigsetjmp:
 313      if (CI->getType() != Type::VoidTy)
 314        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 315      break;
 316
 317   case Intrinsic::longjmp: {
 318     static Function *LongjmpFCache = 0;
 319     ReplaceCallWith("longjmp", CI, CI->op_begin()+1, CI->op_end(),
 320                     Type::VoidTy, LongjmpFCache);
 321     break;
 322   }
 323
 324   case Intrinsic::siglongjmp: {
 325     // Insert the call to abort
 326     static Function *AbortFCache = 0;
 327     ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(), Type::VoidTy,
 328                     AbortFCache);
 329     break;
 330   }
 331   case Intrinsic::ctpop_i8:
 332   case Intrinsic::ctpop_i16:
 333   case Intrinsic::ctpop_i32:
 334   case Intrinsic::ctpop_i64:
 335     CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
 336     break;
 337
 338   case Intrinsic::bswap_i16:
 339   case Intrinsic::bswap_i32:
 340   case Intrinsic::bswap_i64:
 341     CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
 342     break;
 343
 344   case Intrinsic::ctlz_i8:
 345   case Intrinsic::ctlz_i16:
 346   case Intrinsic::ctlz_i32:
 347   case Intrinsic::ctlz_i64:
 348     CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
 349     break;
 350
 351   case Intrinsic::cttz_i8:
 352   case Intrinsic::cttz_i16:
 353   case Intrinsic::cttz_i32:
 354   case Intrinsic::cttz_i64: {
 355     // cttz(x) -> ctpop(~X & (X-1))
 356     Value *Src = CI->getOperand(1);
 357     Value *NotSrc = BinaryOperator::createNot(Src, Src->getName()+".not", CI);
 358     Value *SrcM1  = ConstantInt::get(Src->getType(), 1);
 359     SrcM1 = BinaryOperator::createSub(Src, SrcM1, "", CI);
 360     Src = LowerCTPOP(BinaryOperator::createAnd(NotSrc, SrcM1, "", CI), CI);
 361     CI->replaceAllUsesWith(Src);
 362     break;
 363   }
 364
 365   case Intrinsic::stacksave:
 366   case Intrinsic::stackrestore: {
 367     static bool Warned = false;
 368     if (!Warned)
 369       std::cerr << "WARNING: this target does not support the llvm.stack"
 370        << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
 371            "save" : "restore") << " intrinsic.\n";
 372     Warned = true;
 373     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
 374       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 375     break;
 376   }
 377
 378   case Intrinsic::returnaddress:
 379   case Intrinsic::frameaddress:
 380     std::cerr << "WARNING: this target does not support the llvm."
 381               << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
 382                   "return" : "frame") << "address intrinsic.\n";
 383     CI->replaceAllUsesWith(ConstantPointerNull::get(
 384                                             cast<PointerType>(CI->getType())));
 385     break;
 386
 387   case Intrinsic::prefetch:
 388     break;    // Simply strip out prefetches on unsupported architectures
 389
 390   case Intrinsic::pcmarker:
 391     break;    // Simply strip out pcmarker on unsupported architectures
 392   case Intrinsic::readcyclecounter: {
 393     std::cerr << "WARNING: this target does not support the llvm.readcyclecoun"
 394               << "ter intrinsic.  It is being lowered to a constant 0\n";
 395     CI->replaceAllUsesWith(ConstantUInt::get(Type::ULongTy, 0));
 396     break;
 397   }
 398
 399   case Intrinsic::dbg_stoppoint:
 400   case Intrinsic::dbg_region_start:
 401   case Intrinsic::dbg_region_end:
 402   case Intrinsic::dbg_declare:
 403   case Intrinsic::dbg_func_start:
 404     if (CI->getType() != Type::VoidTy)
 405       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
 406     break;    // Simply strip out debugging intrinsics
 407
 408   case Intrinsic::memcpy: {
 409     // The memcpy intrinsic take an extra alignment argument that the memcpy
 410     // libc function does not.
 411     static Function *MemcpyFCache = 0;
 412     ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
 413                     (*(CI->op_begin()+1))->getType(), MemcpyFCache);
 414     break;
 415   }
 416   case Intrinsic::memmove: {
 417     // The memmove intrinsic take an extra alignment argument that the memmove
 418     // libc function does not.
 419     static Function *MemmoveFCache = 0;
 420     ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
 421                     (*(CI->op_begin()+1))->getType(), MemmoveFCache);
 422     break;
 423   }
 424   case Intrinsic::memset: {
 425     // The memset intrinsic take an extra alignment argument that the memset
 426     // libc function does not.
 427     static Function *MemsetFCache = 0;
 428     ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
 429                     (*(CI->op_begin()+1))->getType(), MemsetFCache);
 430     break;
 431   }
 432   case Intrinsic::isunordered_f32:
 433   case Intrinsic::isunordered_f64: {
 434     Value *L = CI->getOperand(1);
 435     Value *R = CI->getOperand(2);
 436
 437     Value *LIsNan = new SetCondInst(Instruction::SetNE, L, L, "LIsNan", CI);
 438     Value *RIsNan = new SetCondInst(Instruction::SetNE, R, R, "RIsNan", CI);
 439     CI->replaceAllUsesWith(
 440       BinaryOperator::create(Instruction::Or, LIsNan, RIsNan,
 441                              "isunordered", CI));
 442     break;
 443   }
 444   case Intrinsic::sqrt_f32:
 445   case Intrinsic::sqrt_f64: {
 446     static Function *sqrtFCache = 0;
 447     static Function *sqrtfFCache = 0;
 448     if(CI->getType() == Type::FloatTy)
 449       ReplaceCallWith("sqrtf", CI, CI->op_begin()+1, CI->op_end(),
 450                       Type::FloatTy, sqrtfFCache);
 451     else
 452       ReplaceCallWith("sqrt", CI, CI->op_begin()+1, CI->op_end(),
 453                       Type::DoubleTy, sqrtFCache);
 454     break;
 455   }
 456   }
 457
 458   assert(CI->use_empty() &&
 459          "Lowering should have eliminated any uses of the intrinsic call!");
 460   CI->eraseFromParent();
 461 }