IntrinsicLowering.cpp revision 675d56222b6b98d2c22a17aaf69a036e57d5426a 
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/Support/ErrorHandling.h"
21#include "llvm/Target/TargetData.h"
22#include "llvm/ADT/SmallVector.h"
23using namespace llvm;
24
25template <class ArgIt>
26static void EnsureFunctionExists(Module &M, const char *Name,
27                                 ArgIt ArgBegin, ArgIt ArgEnd,
28                                 const Type *RetTy) {
29  // Insert a correctly-typed definition now.
30  std::vector<const Type *> ParamTys;
31  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
32    ParamTys.push_back(I->getType());
33  M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
34}
35
36static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
37                                    const char *FName,
38                                    const char *DName, const char *LDName) {
39  // Insert definitions for all the floating point types.
40  switch((int)Fn->arg_begin()->getType()->getTypeID()) {
41  case Type::FloatTyID:
42    EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
43                         Type::FloatTy);
44    break;
45  case Type::DoubleTyID:
46    EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
47                         Type::DoubleTy);
48    break;
49  case Type::X86_FP80TyID:
50  case Type::FP128TyID:
51  case Type::PPC_FP128TyID:
52    EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
53                         Fn->arg_begin()->getType());
54    break;
55  }
56}
57
58/// ReplaceCallWith - This function is used when we want to lower an intrinsic
59/// call to a call of an external function.  This handles hard cases such as
60/// when there was already a prototype for the external function, and if that
61/// prototype doesn't match the arguments we expect to pass in.
62template <class ArgIt>
63static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
64                                 ArgIt ArgBegin, ArgIt ArgEnd,
65                                 const Type *RetTy) {
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  Constant* FCache = M->getOrInsertFunction(NewFn,
74                                  FunctionType::get(RetTy, ParamTys, false));
75
76  IRBuilder<> Builder(CI->getParent(), CI);
77  SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
78  CallInst *NewCI = Builder.CreateCall(FCache, Args.begin(), Args.end());
79  NewCI->setName(CI->getName());
80  if (!CI->use_empty())
81    CI->replaceAllUsesWith(NewCI);
82  return NewCI;
83}
84
85void IntrinsicLowering::AddPrototypes(Module &M) {
86  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
87    if (I->isDeclaration() && !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::Int32Ty);
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        M.getOrInsertFunction("memcpy", PointerType::getUnqual(Type::Int8Ty),
104                              PointerType::getUnqual(Type::Int8Ty),
105                              PointerType::getUnqual(Type::Int8Ty),
106                              TD.getIntPtrType(), (Type *)0);
107        break;
108      case Intrinsic::memmove:
109        M.getOrInsertFunction("memmove", PointerType::getUnqual(Type::Int8Ty),
110                              PointerType::getUnqual(Type::Int8Ty),
111                              PointerType::getUnqual(Type::Int8Ty),
112                              TD.getIntPtrType(), (Type *)0);
113        break;
114      case Intrinsic::memset:
115        M.getOrInsertFunction("memset", PointerType::getUnqual(Type::Int8Ty),
116                              PointerType::getUnqual(Type::Int8Ty),
117                              Type::Int32Ty,
118                              TD.getIntPtrType(), (Type *)0);
119        break;
120      case Intrinsic::sqrt:
121        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
122        break;
123      case Intrinsic::sin:
124        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
125        break;
126      case Intrinsic::cos:
127        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
128        break;
129      case Intrinsic::pow:
130        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
131        break;
132      case Intrinsic::log:
133        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
134        break;
135      case Intrinsic::log2:
136        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
137        break;
138      case Intrinsic::log10:
139        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
140        break;
141      case Intrinsic::exp:
142        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
143        break;
144      case Intrinsic::exp2:
145        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
146        break;
147      }
148}
149
150/// LowerBSWAP - Emit the code to lower bswap of V before the specified
151/// instruction IP.
152static Value *LowerBSWAP(Value *V, Instruction *IP) {
153  assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
154
155  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
156
157  IRBuilder<> Builder(IP->getParent(), IP);
158
159  switch(BitSize) {
160  default: LLVM_UNREACHABLE("Unhandled type size of value to byteswap!");
161  case 16: {
162    Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
163                                    "bswap.2");
164    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
165                                     "bswap.1");
166    V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
167    break;
168  }
169  case 32: {
170    Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
171                                    "bswap.4");
172    Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
173                                    "bswap.3");
174    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
175                                     "bswap.2");
176    Value *Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
177                                     "bswap.1");
178    Tmp3 = Builder.CreateAnd(Tmp3, ConstantInt::get(Type::Int32Ty, 0xFF0000),
179                             "bswap.and3");
180    Tmp2 = Builder.CreateAnd(Tmp2, ConstantInt::get(Type::Int32Ty, 0xFF00),
181                             "bswap.and2");
182    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
183    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
184    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
185    break;
186  }
187  case 64: {
188    Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
189                                    "bswap.8");
190    Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
191                                    "bswap.7");
192    Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
193                                    "bswap.6");
194    Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
195                                    "bswap.5");
196    Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
197                                     "bswap.4");
198    Value* Tmp3 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
199                                     "bswap.3");
200    Value* Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 40),
201                                     "bswap.2");
202    Value* Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 56),
203                                     "bswap.1");
204    Tmp7 = Builder.CreateAnd(Tmp7,
205                             ConstantInt::get(Type::Int64Ty,
206                                              0xFF000000000000ULL),
207                             "bswap.and7");
208    Tmp6 = Builder.CreateAnd(Tmp6,
209                             ConstantInt::get(Type::Int64Ty,
210                                              0xFF0000000000ULL),
211                             "bswap.and6");
212    Tmp5 = Builder.CreateAnd(Tmp5,
213                             ConstantInt::get(Type::Int64Ty, 0xFF00000000ULL),
214                             "bswap.and5");
215    Tmp4 = Builder.CreateAnd(Tmp4,
216                             ConstantInt::get(Type::Int64Ty, 0xFF000000ULL),
217                             "bswap.and4");
218    Tmp3 = Builder.CreateAnd(Tmp3,
219                             ConstantInt::get(Type::Int64Ty, 0xFF0000ULL),
220                             "bswap.and3");
221    Tmp2 = Builder.CreateAnd(Tmp2,
222                             ConstantInt::get(Type::Int64Ty, 0xFF00ULL),
223                             "bswap.and2");
224    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
225    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
226    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
227    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
228    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
229    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
230    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
231    break;
232  }
233  }
234  return V;
235}
236
237/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
238/// instruction IP.
239static Value *LowerCTPOP(Value *V, Instruction *IP) {
240  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
241
242  static const uint64_t MaskValues[6] = {
243    0x5555555555555555ULL, 0x3333333333333333ULL,
244    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
245    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
246  };
247
248  IRBuilder<> Builder(IP->getParent(), IP);
249
250  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
251  unsigned WordSize = (BitSize + 63) / 64;
252  Value *Count = ConstantInt::get(V->getType(), 0);
253
254  for (unsigned n = 0; n < WordSize; ++n) {
255    Value *PartValue = V;
256    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
257         i <<= 1, ++ct) {
258      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
259      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
260      Value *VShift = Builder.CreateLShr(PartValue,
261                                         ConstantInt::get(V->getType(), i),
262                                         "ctpop.sh");
263      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
264      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
265    }
266    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
267    if (BitSize > 64) {
268      V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
269                             "ctpop.part.sh");
270      BitSize -= 64;
271    }
272  }
273
274  return Count;
275}
276
277/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
278/// instruction IP.
279static Value *LowerCTLZ(Value *V, Instruction *IP) {
280
281  IRBuilder<> Builder(IP->getParent(), IP);
282
283  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
284  for (unsigned i = 1; i < BitSize; i <<= 1) {
285    Value *ShVal = ConstantInt::get(V->getType(), i);
286    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
287    V = Builder.CreateOr(V, ShVal, "ctlz.step");
288  }
289
290  V = Builder.CreateNot(V);
291  return LowerCTPOP(V, IP);
292}
293
294/// Convert the llvm.part.select.iX.iY intrinsic. This intrinsic takes
295/// three integer arguments. The first argument is the Value from which the
296/// bits will be selected. It may be of any bit width. The second and third
297/// arguments specify a range of bits to select with the second argument
298/// specifying the low bit and the third argument specifying the high bit. Both
299/// must be type i32. The result is the corresponding selected bits from the
300/// Value in the same width as the Value (first argument). If the low bit index
301/// is higher than the high bit index then the inverse selection is done and
302/// the bits are returned in inverse order.
303/// @brief Lowering of llvm.part.select intrinsic.
304static Instruction *LowerPartSelect(CallInst *CI) {
305  IRBuilder<> Builder(*CI->getParent()->getContext());
306
307  // Make sure we're dealing with a part select intrinsic here
308  Function *F = CI->getCalledFunction();
309  const FunctionType *FT = F->getFunctionType();
310  if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
311      FT->getNumParams() != 3 || !FT->getParamType(0)->isInteger() ||
312      !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger())
313    return CI;
314
315  // Get the intrinsic implementation function by converting all the . to _
316  // in the intrinsic's function name and then reconstructing the function
317  // declaration.
318  std::string Name(F->getName());
319  for (unsigned i = 4; i < Name.length(); ++i)
320    if (Name[i] == '.')
321      Name[i] = '_';
322  Module* M = F->getParent();
323  F = cast<Function>(M->getOrInsertFunction(Name, FT));
324  F->setLinkage(GlobalValue::WeakAnyLinkage);
325
326  // If we haven't defined the impl function yet, do so now
327  if (F->isDeclaration()) {
328
329    // Get the arguments to the function
330    Function::arg_iterator args = F->arg_begin();
331    Value* Val = args++; Val->setName("Val");
332    Value* Lo = args++; Lo->setName("Lo");
333    Value* Hi = args++; Hi->setName("High");
334
335    // We want to select a range of bits here such that [Hi, Lo] is shifted
336    // down to the low bits. However, it is quite possible that Hi is smaller
337    // than Lo in which case the bits have to be reversed.
338
339    // Create the blocks we will need for the two cases (forward, reverse)
340    BasicBlock* CurBB   = BasicBlock::Create("entry", F);
341    BasicBlock *RevSize = BasicBlock::Create("revsize", CurBB->getParent());
342    BasicBlock *FwdSize = BasicBlock::Create("fwdsize", CurBB->getParent());
343    BasicBlock *Compute = BasicBlock::Create("compute", CurBB->getParent());
344    BasicBlock *Reverse = BasicBlock::Create("reverse", CurBB->getParent());
345    BasicBlock *RsltBlk = BasicBlock::Create("result",  CurBB->getParent());
346
347    Builder.SetInsertPoint(CurBB);
348
349    // Cast Hi and Lo to the size of Val so the widths are all the same
350    if (Hi->getType() != Val->getType())
351      Hi = Builder.CreateIntCast(Hi, Val->getType(), /* isSigned */ false,
352                                 "tmp");
353    if (Lo->getType() != Val->getType())
354      Lo = Builder.CreateIntCast(Lo, Val->getType(), /* isSigned */ false,
355                                 "tmp");
356
357    // Compute a few things that both cases will need, up front.
358    Constant* Zero = ConstantInt::get(Val->getType(), 0);
359    Constant* One = ConstantInt::get(Val->getType(), 1);
360    Constant* AllOnes = ConstantInt::getAllOnesValue(Val->getType());
361
362    // Compare the Hi and Lo bit positions. This is used to determine
363    // which case we have (forward or reverse)
364    Value *Cmp = Builder.CreateICmpULT(Hi, Lo, "less");
365    Builder.CreateCondBr(Cmp, RevSize, FwdSize);
366
367    // First, compute the number of bits in the forward case.
368    Builder.SetInsertPoint(FwdSize);
369    Value* FBitSize = Builder.CreateSub(Hi, Lo, "fbits");
370    Builder.CreateBr(Compute);
371
372    // Second, compute the number of bits in the reverse case.
373    Builder.SetInsertPoint(RevSize);
374    Value* RBitSize = Builder.CreateSub(Lo, Hi, "rbits");
375    Builder.CreateBr(Compute);
376
377    // Now, compute the bit range. Start by getting the bitsize and the shift
378    // amount (either Hi or Lo) from PHI nodes. Then we compute a mask for
379    // the number of bits we want in the range. We shift the bits down to the
380    // least significant bits, apply the mask to zero out unwanted high bits,
381    // and we have computed the "forward" result. It may still need to be
382    // reversed.
383    Builder.SetInsertPoint(Compute);
384
385    // Get the BitSize from one of the two subtractions
386    PHINode *BitSize = Builder.CreatePHI(Val->getType(), "bits");
387    BitSize->reserveOperandSpace(2);
388    BitSize->addIncoming(FBitSize, FwdSize);
389    BitSize->addIncoming(RBitSize, RevSize);
390
391    // Get the ShiftAmount as the smaller of Hi/Lo
392    PHINode *ShiftAmt = Builder.CreatePHI(Val->getType(), "shiftamt");
393    ShiftAmt->reserveOperandSpace(2);
394    ShiftAmt->addIncoming(Lo, FwdSize);
395    ShiftAmt->addIncoming(Hi, RevSize);
396
397    // Increment the bit size
398    Value *BitSizePlusOne = Builder.CreateAdd(BitSize, One, "bits");
399
400    // Create a Mask to zero out the high order bits.
401    Value* Mask = Builder.CreateShl(AllOnes, BitSizePlusOne, "mask");
402    Mask = Builder.CreateNot(Mask, "mask");
403
404    // Shift the bits down and apply the mask
405    Value* FRes = Builder.CreateLShr(Val, ShiftAmt, "fres");
406    FRes = Builder.CreateAnd(FRes, Mask, "fres");
407    Builder.CreateCondBr(Cmp, Reverse, RsltBlk);
408
409    // In the Reverse block we have the mask already in FRes but we must reverse
410    // it by shifting FRes bits right and putting them in RRes by shifting them
411    // in from left.
412    Builder.SetInsertPoint(Reverse);
413
414    // First set up our loop counters
415    PHINode *Count = Builder.CreatePHI(Val->getType(), "count");
416    Count->reserveOperandSpace(2);
417    Count->addIncoming(BitSizePlusOne, Compute);
418
419    // Next, get the value that we are shifting.
420    PHINode *BitsToShift = Builder.CreatePHI(Val->getType(), "val");
421    BitsToShift->reserveOperandSpace(2);
422    BitsToShift->addIncoming(FRes, Compute);
423
424    // Finally, get the result of the last computation
425    PHINode *RRes = Builder.CreatePHI(Val->getType(), "rres");
426    RRes->reserveOperandSpace(2);
427    RRes->addIncoming(Zero, Compute);
428
429    // Decrement the counter
430    Value *Decr = Builder.CreateSub(Count, One, "decr");
431    Count->addIncoming(Decr, Reverse);
432
433    // Compute the Bit that we want to move
434    Value *Bit = Builder.CreateAnd(BitsToShift, One, "bit");
435
436    // Compute the new value for next iteration.
437    Value *NewVal = Builder.CreateLShr(BitsToShift, One, "rshift");
438    BitsToShift->addIncoming(NewVal, Reverse);
439
440    // Shift the bit into the low bits of the result.
441    Value *NewRes = Builder.CreateShl(RRes, One, "lshift");
442    NewRes = Builder.CreateOr(NewRes, Bit, "addbit");
443    RRes->addIncoming(NewRes, Reverse);
444
445    // Terminate loop if we've moved all the bits.
446    Value *Cond = Builder.CreateICmpEQ(Decr, Zero, "cond");
447    Builder.CreateCondBr(Cond, RsltBlk, Reverse);
448
449    // Finally, in the result block, select one of the two results with a PHI
450    // node and return the result;
451    Builder.SetInsertPoint(RsltBlk);
452    PHINode *BitSelect = Builder.CreatePHI(Val->getType(), "part_select");
453    BitSelect->reserveOperandSpace(2);
454    BitSelect->addIncoming(FRes, Compute);
455    BitSelect->addIncoming(NewRes, Reverse);
456    Builder.CreateRet(BitSelect);
457  }
458
459  // Return a call to the implementation function
460  Builder.SetInsertPoint(CI->getParent(), CI);
461  CallInst *NewCI = Builder.CreateCall3(F, CI->getOperand(1),
462                                        CI->getOperand(2), CI->getOperand(3));
463  NewCI->setName(CI->getName());
464  return NewCI;
465}
466
467/// Convert the llvm.part.set.iX.iY.iZ intrinsic. This intrinsic takes
468/// four integer arguments (iAny %Value, iAny %Replacement, i32 %Low, i32 %High)
469/// The first two arguments can be any bit width. The result is the same width
470/// as %Value. The operation replaces bits between %Low and %High with the value
471/// in %Replacement. If %Replacement is not the same width, it is truncated or
472/// zero extended as appropriate to fit the bits being replaced. If %Low is
473/// greater than %High then the inverse set of bits are replaced.
474/// @brief Lowering of llvm.bit.part.set intrinsic.
475static Instruction *LowerPartSet(CallInst *CI) {
476  IRBuilder<> Builder(*CI->getParent()->getContext());
477
478  // Make sure we're dealing with a part select intrinsic here
479  Function *F = CI->getCalledFunction();
480  const FunctionType *FT = F->getFunctionType();
481  if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
482      FT->getNumParams() != 4 || !FT->getParamType(0)->isInteger() ||
483      !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger() ||
484      !FT->getParamType(3)->isInteger())
485    return CI;
486
487  // Get the intrinsic implementation function by converting all the . to _
488  // in the intrinsic's function name and then reconstructing the function
489  // declaration.
490  std::string Name(F->getName());
491  for (unsigned i = 4; i < Name.length(); ++i)
492    if (Name[i] == '.')
493      Name[i] = '_';
494  Module* M = F->getParent();
495  F = cast<Function>(M->getOrInsertFunction(Name, FT));
496  F->setLinkage(GlobalValue::WeakAnyLinkage);
497
498  // If we haven't defined the impl function yet, do so now
499  if (F->isDeclaration()) {
500    // Get the arguments for the function.
501    Function::arg_iterator args = F->arg_begin();
502    Value* Val = args++; Val->setName("Val");
503    Value* Rep = args++; Rep->setName("Rep");
504    Value* Lo  = args++; Lo->setName("Lo");
505    Value* Hi  = args++; Hi->setName("Hi");
506
507    // Get some types we need
508    const IntegerType* ValTy = cast<IntegerType>(Val->getType());
509    const IntegerType* RepTy = cast<IntegerType>(Rep->getType());
510    uint32_t RepBits = RepTy->getBitWidth();
511
512    // Constant Definitions
513    ConstantInt* RepBitWidth = ConstantInt::get(Type::Int32Ty, RepBits);
514    ConstantInt* RepMask = ConstantInt::getAllOnesValue(RepTy);
515    ConstantInt* ValMask = ConstantInt::getAllOnesValue(ValTy);
516    ConstantInt* One = ConstantInt::get(Type::Int32Ty, 1);
517    ConstantInt* ValOne = ConstantInt::get(ValTy, 1);
518    ConstantInt* Zero = ConstantInt::get(Type::Int32Ty, 0);
519    ConstantInt* ValZero = ConstantInt::get(ValTy, 0);
520
521    // Basic blocks we fill in below.
522    BasicBlock* entry = BasicBlock::Create("entry", F, 0);
523    BasicBlock* large = BasicBlock::Create("large", F, 0);
524    BasicBlock* small = BasicBlock::Create("small", F, 0);
525    BasicBlock* reverse = BasicBlock::Create("reverse", F, 0);
526    BasicBlock* result = BasicBlock::Create("result", F, 0);
527
528    // BASIC BLOCK: entry
529    Builder.SetInsertPoint(entry);
530    // First, get the number of bits that we're placing as an i32
531    Value* is_forward = Builder.CreateICmpULT(Lo, Hi);
532    Value* Hi_pn = Builder.CreateSelect(is_forward, Hi, Lo);
533    Value* Lo_pn = Builder.CreateSelect(is_forward, Lo, Hi);
534    Value* NumBits = Builder.CreateSub(Hi_pn, Lo_pn);
535    NumBits = Builder.CreateAdd(NumBits, One);
536    // Now, convert Lo and Hi to ValTy bit width
537    Lo = Builder.CreateIntCast(Lo_pn, ValTy, /* isSigned */ false);
538    // Determine if the replacement bits are larger than the number of bits we
539    // are replacing and deal with it.
540    Value* is_large = Builder.CreateICmpULT(NumBits, RepBitWidth);
541    Builder.CreateCondBr(is_large, large, small);
542
543    // BASIC BLOCK: large
544    Builder.SetInsertPoint(large);
545    Value* MaskBits = Builder.CreateSub(RepBitWidth, NumBits);
546    MaskBits = Builder.CreateIntCast(MaskBits, RepMask->getType(),
547                                     /* isSigned */ false);
548    Value* Mask1 = Builder.CreateLShr(RepMask, MaskBits);
549    Value* Rep2 = Builder.CreateAnd(Mask1, Rep);
550    Builder.CreateBr(small);
551
552    // BASIC BLOCK: small
553    Builder.SetInsertPoint(small);
554    PHINode* Rep3 = Builder.CreatePHI(RepTy);
555    Rep3->reserveOperandSpace(2);
556    Rep3->addIncoming(Rep2, large);
557    Rep3->addIncoming(Rep, entry);
558    Value* Rep4 = Builder.CreateIntCast(Rep3, ValTy, /* isSigned */ false);
559    Builder.CreateCondBr(is_forward, result, reverse);
560
561    // BASIC BLOCK: reverse (reverses the bits of the replacement)
562    Builder.SetInsertPoint(reverse);
563    // Set up our loop counter as a PHI so we can decrement on each iteration.
564    // We will loop for the number of bits in the replacement value.
565    PHINode *Count = Builder.CreatePHI(Type::Int32Ty, "count");
566    Count->reserveOperandSpace(2);
567    Count->addIncoming(NumBits, small);
568
569    // Get the value that we are shifting bits out of as a PHI because
570    // we'll change this with each iteration.
571    PHINode *BitsToShift = Builder.CreatePHI(Val->getType(), "val");
572    BitsToShift->reserveOperandSpace(2);
573    BitsToShift->addIncoming(Rep4, small);
574
575    // Get the result of the last computation or zero on first iteration
576    PHINode *RRes = Builder.CreatePHI(Val->getType(), "rres");
577    RRes->reserveOperandSpace(2);
578    RRes->addIncoming(ValZero, small);
579
580    // Decrement the loop counter by one
581    Value *Decr = Builder.CreateSub(Count, One);
582    Count->addIncoming(Decr, reverse);
583
584    // Get the bit that we want to move into the result
585    Value *Bit = Builder.CreateAnd(BitsToShift, ValOne);
586
587    // Compute the new value of the bits to shift for the next iteration.
588    Value *NewVal = Builder.CreateLShr(BitsToShift, ValOne);
589    BitsToShift->addIncoming(NewVal, reverse);
590
591    // Shift the bit we extracted into the low bit of the result.
592    Value *NewRes = Builder.CreateShl(RRes, ValOne);
593    NewRes = Builder.CreateOr(NewRes, Bit);
594    RRes->addIncoming(NewRes, reverse);
595
596    // Terminate loop if we've moved all the bits.
597    Value *Cond = Builder.CreateICmpEQ(Decr, Zero);
598    Builder.CreateCondBr(Cond, result, reverse);
599
600    // BASIC BLOCK: result
601    Builder.SetInsertPoint(result);
602    PHINode *Rplcmnt = Builder.CreatePHI(Val->getType());
603    Rplcmnt->reserveOperandSpace(2);
604    Rplcmnt->addIncoming(NewRes, reverse);
605    Rplcmnt->addIncoming(Rep4, small);
606    Value* t0   = Builder.CreateIntCast(NumBits, ValTy, /* isSigned */ false);
607    Value* t1   = Builder.CreateShl(ValMask, Lo);
608    Value* t2   = Builder.CreateNot(t1);
609    Value* t3   = Builder.CreateShl(t1, t0);
610    Value* t4   = Builder.CreateOr(t2, t3);
611    Value* t5   = Builder.CreateAnd(t4, Val);
612    Value* t6   = Builder.CreateShl(Rplcmnt, Lo);
613    Value* Rslt = Builder.CreateOr(t5, t6, "part_set");
614    Builder.CreateRet(Rslt);
615  }
616
617  // Return a call to the implementation function
618  Builder.SetInsertPoint(CI->getParent(), CI);
619  CallInst *NewCI = Builder.CreateCall4(F, CI->getOperand(1),
620                                        CI->getOperand(2), CI->getOperand(3),
621                                        CI->getOperand(4));
622  NewCI->setName(CI->getName());
623  return NewCI;
624}
625
626static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
627                                       const char *Dname,
628                                       const char *LDname) {
629  switch (CI->getOperand(1)->getType()->getTypeID()) {
630  default: LLVM_UNREACHABLE( "Invalid type in intrinsic");
631  case Type::FloatTyID:
632    ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
633                  Type::FloatTy);
634    break;
635  case Type::DoubleTyID:
636    ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
637                  Type::DoubleTy);
638    break;
639  case Type::X86_FP80TyID:
640  case Type::FP128TyID:
641  case Type::PPC_FP128TyID:
642    ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
643                  CI->getOperand(1)->getType());
644    break;
645  }
646}
647
648void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
649  IRBuilder<> Builder(CI->getParent(), CI);
650
651  Function *Callee = CI->getCalledFunction();
652  assert(Callee && "Cannot lower an indirect call!");
653
654  switch (Callee->getIntrinsicID()) {
655  case Intrinsic::not_intrinsic:
656    llvm_report_error("Cannot lower a call to a non-intrinsic function '"+
657                      Callee->getName() + "'!");
658  default:
659    llvm_report_error("Code generator does not support intrinsic function '"+
660                      Callee->getName()+"'!");
661
662    // The setjmp/longjmp intrinsics should only exist in the code if it was
663    // never optimized (ie, right out of the CFE), or if it has been hacked on
664    // by the lowerinvoke pass.  In both cases, the right thing to do is to
665    // convert the call to an explicit setjmp or longjmp call.
666  case Intrinsic::setjmp: {
667    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
668                               Type::Int32Ty);
669    if (CI->getType() != Type::VoidTy)
670      CI->replaceAllUsesWith(V);
671    break;
672  }
673  case Intrinsic::sigsetjmp:
674     if (CI->getType() != Type::VoidTy)
675       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
676     break;
677
678  case Intrinsic::longjmp: {
679    ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
680                    Type::VoidTy);
681    break;
682  }
683
684  case Intrinsic::siglongjmp: {
685    // Insert the call to abort
686    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
687                    Type::VoidTy);
688    break;
689  }
690  case Intrinsic::ctpop:
691    CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
692    break;
693
694  case Intrinsic::bswap:
695    CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
696    break;
697
698  case Intrinsic::ctlz:
699    CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
700    break;
701
702  case Intrinsic::cttz: {
703    // cttz(x) -> ctpop(~X & (X-1))
704    Value *Src = CI->getOperand(1);
705    Value *NotSrc = Builder.CreateNot(Src);
706    NotSrc->setName(Src->getName() + ".not");
707    Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
708    SrcM1 = Builder.CreateSub(Src, SrcM1);
709    Src = LowerCTPOP(Builder.CreateAnd(NotSrc, SrcM1), CI);
710    CI->replaceAllUsesWith(Src);
711    break;
712  }
713
714  case Intrinsic::part_select:
715    CI->replaceAllUsesWith(LowerPartSelect(CI));
716    break;
717
718  case Intrinsic::part_set:
719    CI->replaceAllUsesWith(LowerPartSet(CI));
720    break;
721
722  case Intrinsic::stacksave:
723  case Intrinsic::stackrestore: {
724    if (!Warned)
725      cerr << "WARNING: this target does not support the llvm.stack"
726           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
727               "save" : "restore") << " intrinsic.\n";
728    Warned = true;
729    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
730      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
731    break;
732  }
733
734  case Intrinsic::returnaddress:
735  case Intrinsic::frameaddress:
736    cerr << "WARNING: this target does not support the llvm."
737         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
738             "return" : "frame") << "address intrinsic.\n";
739    CI->replaceAllUsesWith(ConstantPointerNull::get(
740                                            cast<PointerType>(CI->getType())));
741    break;
742
743  case Intrinsic::prefetch:
744    break;    // Simply strip out prefetches on unsupported architectures
745
746  case Intrinsic::pcmarker:
747    break;    // Simply strip out pcmarker on unsupported architectures
748  case Intrinsic::readcyclecounter: {
749    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
750         << "ter intrinsic.  It is being lowered to a constant 0\n";
751    CI->replaceAllUsesWith(ConstantInt::get(Type::Int64Ty, 0));
752    break;
753  }
754
755  case Intrinsic::dbg_stoppoint:
756  case Intrinsic::dbg_region_start:
757  case Intrinsic::dbg_region_end:
758  case Intrinsic::dbg_func_start:
759  case Intrinsic::dbg_declare:
760    break;    // Simply strip out debugging intrinsics
761
762  case Intrinsic::eh_exception:
763  case Intrinsic::eh_selector_i32:
764  case Intrinsic::eh_selector_i64:
765    CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
766    break;
767
768  case Intrinsic::eh_typeid_for_i32:
769  case Intrinsic::eh_typeid_for_i64:
770    // Return something different to eh_selector.
771    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
772    break;
773
774  case Intrinsic::var_annotation:
775    break;   // Strip out annotate intrinsic
776
777  case Intrinsic::memcpy: {
778    const IntegerType *IntPtr = TD.getIntPtrType();
779    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
780                                        /* isSigned */ false);
781    Value *Ops[3];
782    Ops[0] = CI->getOperand(1);
783    Ops[1] = CI->getOperand(2);
784    Ops[2] = Size;
785    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType());
786    break;
787  }
788  case Intrinsic::memmove: {
789    const IntegerType *IntPtr = TD.getIntPtrType();
790    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
791                                        /* isSigned */ false);
792    Value *Ops[3];
793    Ops[0] = CI->getOperand(1);
794    Ops[1] = CI->getOperand(2);
795    Ops[2] = Size;
796    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType());
797    break;
798  }
799  case Intrinsic::memset: {
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    // Extend the amount to i32.
806    Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::Int32Ty,
807                                   /* isSigned */ false);
808    Ops[2] = Size;
809    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType());
810    break;
811  }
812  case Intrinsic::sqrt: {
813    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
814    break;
815  }
816  case Intrinsic::log: {
817    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
818    break;
819  }
820  case Intrinsic::log2: {
821    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
822    break;
823  }
824  case Intrinsic::log10: {
825    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
826    break;
827  }
828  case Intrinsic::exp: {
829    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
830    break;
831  }
832  case Intrinsic::exp2: {
833    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
834    break;
835  }
836  case Intrinsic::pow: {
837    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
838    break;
839  }
840  case Intrinsic::flt_rounds:
841     // Lower to "round to the nearest"
842     if (CI->getType() != Type::VoidTy)
843       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
844     break;
845  }
846
847  assert(CI->use_empty() &&
848         "Lowering should have eliminated any uses of the intrinsic call!");
849  CI->eraseFromParent();
850}
851