IntrinsicLowering.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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/CodeGen/IntrinsicLowering.h"
15#include "llvm/ADT/SmallVector.h"
16#include "llvm/IR/CallSite.h"
17#include "llvm/IR/Constants.h"
18#include "llvm/IR/DataLayout.h"
19#include "llvm/IR/DerivedTypes.h"
20#include "llvm/IR/IRBuilder.h"
21#include "llvm/IR/Module.h"
22#include "llvm/IR/Type.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/raw_ostream.h"
25using namespace llvm;
26
27template <class ArgIt>
28static void EnsureFunctionExists(Module &M, const char *Name,
29                                 ArgIt ArgBegin, ArgIt ArgEnd,
30                                 Type *RetTy) {
31  // Insert a correctly-typed definition now.
32  std::vector<Type *> ParamTys;
33  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
34    ParamTys.push_back(I->getType());
35  M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
36}
37
38static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
39                                    const char *FName,
40                                    const char *DName, const char *LDName) {
41  // Insert definitions for all the floating point types.
42  switch((int)Fn->arg_begin()->getType()->getTypeID()) {
43  case Type::FloatTyID:
44    EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
45                         Type::getFloatTy(M.getContext()));
46    break;
47  case Type::DoubleTyID:
48    EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
49                         Type::getDoubleTy(M.getContext()));
50    break;
51  case Type::X86_FP80TyID:
52  case Type::FP128TyID:
53  case Type::PPC_FP128TyID:
54    EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
55                         Fn->arg_begin()->getType());
56    break;
57  }
58}
59
60/// ReplaceCallWith - This function is used when we want to lower an intrinsic
61/// call to a call of an external function.  This handles hard cases such as
62/// when there was already a prototype for the external function, and if that
63/// prototype doesn't match the arguments we expect to pass in.
64template <class ArgIt>
65static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
66                                 ArgIt ArgBegin, ArgIt ArgEnd,
67                                 Type *RetTy) {
68  // If we haven't already looked up this function, check to see if the
69  // program already contains a function with this name.
70  Module *M = CI->getParent()->getParent()->getParent();
71  // Get or insert the definition now.
72  std::vector<Type *> ParamTys;
73  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
74    ParamTys.push_back((*I)->getType());
75  Constant* FCache = M->getOrInsertFunction(NewFn,
76                                  FunctionType::get(RetTy, ParamTys, false));
77
78  IRBuilder<> Builder(CI->getParent(), CI);
79  SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
80  CallInst *NewCI = Builder.CreateCall(FCache, Args);
81  NewCI->setName(CI->getName());
82  if (!CI->use_empty())
83    CI->replaceAllUsesWith(NewCI);
84  return NewCI;
85}
86
87// VisualStudio defines setjmp as _setjmp
88#if defined(_MSC_VER) && defined(setjmp) && \
89                         !defined(setjmp_undefined_for_msvc)
90#  pragma push_macro("setjmp")
91#  undef setjmp
92#  define setjmp_undefined_for_msvc
93#endif
94
95void IntrinsicLowering::AddPrototypes(Module &M) {
96  LLVMContext &Context = M.getContext();
97  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
98    if (I->isDeclaration() && !I->use_empty())
99      switch (I->getIntrinsicID()) {
100      default: break;
101      case Intrinsic::setjmp:
102        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
103                             Type::getInt32Ty(M.getContext()));
104        break;
105      case Intrinsic::longjmp:
106        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
107                             Type::getVoidTy(M.getContext()));
108        break;
109      case Intrinsic::siglongjmp:
110        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
111                             Type::getVoidTy(M.getContext()));
112        break;
113      case Intrinsic::memcpy:
114        M.getOrInsertFunction("memcpy",
115          Type::getInt8PtrTy(Context),
116                              Type::getInt8PtrTy(Context),
117                              Type::getInt8PtrTy(Context),
118                              DL.getIntPtrType(Context), nullptr);
119        break;
120      case Intrinsic::memmove:
121        M.getOrInsertFunction("memmove",
122          Type::getInt8PtrTy(Context),
123                              Type::getInt8PtrTy(Context),
124                              Type::getInt8PtrTy(Context),
125                              DL.getIntPtrType(Context), nullptr);
126        break;
127      case Intrinsic::memset:
128        M.getOrInsertFunction("memset",
129          Type::getInt8PtrTy(Context),
130                              Type::getInt8PtrTy(Context),
131                              Type::getInt32Ty(M.getContext()),
132                              DL.getIntPtrType(Context), nullptr);
133        break;
134      case Intrinsic::sqrt:
135        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
136        break;
137      case Intrinsic::sin:
138        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
139        break;
140      case Intrinsic::cos:
141        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
142        break;
143      case Intrinsic::pow:
144        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
145        break;
146      case Intrinsic::log:
147        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
148        break;
149      case Intrinsic::log2:
150        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
151        break;
152      case Intrinsic::log10:
153        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
154        break;
155      case Intrinsic::exp:
156        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
157        break;
158      case Intrinsic::exp2:
159        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
160        break;
161      }
162}
163
164/// LowerBSWAP - Emit the code to lower bswap of V before the specified
165/// instruction IP.
166static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
167  assert(V->getType()->isIntegerTy() && "Can't bswap a non-integer type!");
168
169  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
170
171  IRBuilder<> Builder(IP->getParent(), IP);
172
173  switch(BitSize) {
174  default: llvm_unreachable("Unhandled type size of value to byteswap!");
175  case 16: {
176    Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
177                                    "bswap.2");
178    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
179                                     "bswap.1");
180    V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
181    break;
182  }
183  case 32: {
184    Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
185                                    "bswap.4");
186    Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
187                                    "bswap.3");
188    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
189                                     "bswap.2");
190    Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
191                                     "bswap.1");
192    Tmp3 = Builder.CreateAnd(Tmp3,
193                         ConstantInt::get(Type::getInt32Ty(Context), 0xFF0000),
194                             "bswap.and3");
195    Tmp2 = Builder.CreateAnd(Tmp2,
196                           ConstantInt::get(Type::getInt32Ty(Context), 0xFF00),
197                             "bswap.and2");
198    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
199    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
200    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
201    break;
202  }
203  case 64: {
204    Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
205                                    "bswap.8");
206    Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
207                                    "bswap.7");
208    Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
209                                    "bswap.6");
210    Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
211                                    "bswap.5");
212    Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
213                                     "bswap.4");
214    Value* Tmp3 = Builder.CreateLShr(V,
215                                     ConstantInt::get(V->getType(), 24),
216                                     "bswap.3");
217    Value* Tmp2 = Builder.CreateLShr(V,
218                                     ConstantInt::get(V->getType(), 40),
219                                     "bswap.2");
220    Value* Tmp1 = Builder.CreateLShr(V,
221                                     ConstantInt::get(V->getType(), 56),
222                                     "bswap.1");
223    Tmp7 = Builder.CreateAnd(Tmp7,
224                             ConstantInt::get(Type::getInt64Ty(Context),
225                                              0xFF000000000000ULL),
226                             "bswap.and7");
227    Tmp6 = Builder.CreateAnd(Tmp6,
228                             ConstantInt::get(Type::getInt64Ty(Context),
229                                              0xFF0000000000ULL),
230                             "bswap.and6");
231    Tmp5 = Builder.CreateAnd(Tmp5,
232                        ConstantInt::get(Type::getInt64Ty(Context),
233                             0xFF00000000ULL),
234                             "bswap.and5");
235    Tmp4 = Builder.CreateAnd(Tmp4,
236                        ConstantInt::get(Type::getInt64Ty(Context),
237                             0xFF000000ULL),
238                             "bswap.and4");
239    Tmp3 = Builder.CreateAnd(Tmp3,
240                             ConstantInt::get(Type::getInt64Ty(Context),
241                             0xFF0000ULL),
242                             "bswap.and3");
243    Tmp2 = Builder.CreateAnd(Tmp2,
244                             ConstantInt::get(Type::getInt64Ty(Context),
245                             0xFF00ULL),
246                             "bswap.and2");
247    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
248    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
249    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
250    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
251    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
252    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
253    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
254    break;
255  }
256  }
257  return V;
258}
259
260/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
261/// instruction IP.
262static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
263  assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");
264
265  static const uint64_t MaskValues[6] = {
266    0x5555555555555555ULL, 0x3333333333333333ULL,
267    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
268    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
269  };
270
271  IRBuilder<> Builder(IP->getParent(), IP);
272
273  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
274  unsigned WordSize = (BitSize + 63) / 64;
275  Value *Count = ConstantInt::get(V->getType(), 0);
276
277  for (unsigned n = 0; n < WordSize; ++n) {
278    Value *PartValue = V;
279    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
280         i <<= 1, ++ct) {
281      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
282      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
283      Value *VShift = Builder.CreateLShr(PartValue,
284                                        ConstantInt::get(V->getType(), i),
285                                         "ctpop.sh");
286      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
287      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
288    }
289    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
290    if (BitSize > 64) {
291      V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
292                             "ctpop.part.sh");
293      BitSize -= 64;
294    }
295  }
296
297  return Count;
298}
299
300/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
301/// instruction IP.
302static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
303
304  IRBuilder<> Builder(IP->getParent(), IP);
305
306  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
307  for (unsigned i = 1; i < BitSize; i <<= 1) {
308    Value *ShVal = ConstantInt::get(V->getType(), i);
309    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
310    V = Builder.CreateOr(V, ShVal, "ctlz.step");
311  }
312
313  V = Builder.CreateNot(V);
314  return LowerCTPOP(Context, V, IP);
315}
316
317static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
318                                       const char *Dname,
319                                       const char *LDname) {
320  CallSite CS(CI);
321  switch (CI->getArgOperand(0)->getType()->getTypeID()) {
322  default: llvm_unreachable("Invalid type in intrinsic");
323  case Type::FloatTyID:
324    ReplaceCallWith(Fname, CI, CS.arg_begin(), CS.arg_end(),
325                  Type::getFloatTy(CI->getContext()));
326    break;
327  case Type::DoubleTyID:
328    ReplaceCallWith(Dname, CI, CS.arg_begin(), CS.arg_end(),
329                  Type::getDoubleTy(CI->getContext()));
330    break;
331  case Type::X86_FP80TyID:
332  case Type::FP128TyID:
333  case Type::PPC_FP128TyID:
334    ReplaceCallWith(LDname, CI, CS.arg_begin(), CS.arg_end(),
335                  CI->getArgOperand(0)->getType());
336    break;
337  }
338}
339
340void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
341  IRBuilder<> Builder(CI->getParent(), CI);
342  LLVMContext &Context = CI->getContext();
343
344  const Function *Callee = CI->getCalledFunction();
345  assert(Callee && "Cannot lower an indirect call!");
346
347  CallSite CS(CI);
348  switch (Callee->getIntrinsicID()) {
349  case Intrinsic::not_intrinsic:
350    report_fatal_error("Cannot lower a call to a non-intrinsic function '"+
351                      Callee->getName() + "'!");
352  default:
353    report_fatal_error("Code generator does not support intrinsic function '"+
354                      Callee->getName()+"'!");
355
356  case Intrinsic::expect: {
357    // Just replace __builtin_expect(exp, c) with EXP.
358    Value *V = CI->getArgOperand(0);
359    CI->replaceAllUsesWith(V);
360    break;
361  }
362
363    // The setjmp/longjmp intrinsics should only exist in the code if it was
364    // never optimized (ie, right out of the CFE), or if it has been hacked on
365    // by the lowerinvoke pass.  In both cases, the right thing to do is to
366    // convert the call to an explicit setjmp or longjmp call.
367  case Intrinsic::setjmp: {
368    Value *V = ReplaceCallWith("setjmp", CI, CS.arg_begin(), CS.arg_end(),
369                               Type::getInt32Ty(Context));
370    if (!CI->getType()->isVoidTy())
371      CI->replaceAllUsesWith(V);
372    break;
373  }
374  case Intrinsic::sigsetjmp:
375     if (!CI->getType()->isVoidTy())
376       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
377     break;
378
379  case Intrinsic::longjmp: {
380    ReplaceCallWith("longjmp", CI, CS.arg_begin(), CS.arg_end(),
381                    Type::getVoidTy(Context));
382    break;
383  }
384
385  case Intrinsic::siglongjmp: {
386    // Insert the call to abort
387    ReplaceCallWith("abort", CI, CS.arg_end(), CS.arg_end(),
388                    Type::getVoidTy(Context));
389    break;
390  }
391  case Intrinsic::ctpop:
392    CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI));
393    break;
394
395  case Intrinsic::bswap:
396    CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI));
397    break;
398
399  case Intrinsic::ctlz:
400    CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI));
401    break;
402
403  case Intrinsic::cttz: {
404    // cttz(x) -> ctpop(~X & (X-1))
405    Value *Src = CI->getArgOperand(0);
406    Value *NotSrc = Builder.CreateNot(Src);
407    NotSrc->setName(Src->getName() + ".not");
408    Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
409    SrcM1 = Builder.CreateSub(Src, SrcM1);
410    Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
411    CI->replaceAllUsesWith(Src);
412    break;
413  }
414
415  case Intrinsic::stacksave:
416  case Intrinsic::stackrestore: {
417    if (!Warned)
418      errs() << "WARNING: this target does not support the llvm.stack"
419             << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
420               "save" : "restore") << " intrinsic.\n";
421    Warned = true;
422    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
423      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
424    break;
425  }
426
427  case Intrinsic::returnaddress:
428  case Intrinsic::frameaddress:
429    errs() << "WARNING: this target does not support the llvm."
430           << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
431             "return" : "frame") << "address intrinsic.\n";
432    CI->replaceAllUsesWith(ConstantPointerNull::get(
433                                            cast<PointerType>(CI->getType())));
434    break;
435
436  case Intrinsic::prefetch:
437    break;    // Simply strip out prefetches on unsupported architectures
438
439  case Intrinsic::pcmarker:
440    break;    // Simply strip out pcmarker on unsupported architectures
441  case Intrinsic::readcyclecounter: {
442    errs() << "WARNING: this target does not support the llvm.readcyclecoun"
443           << "ter intrinsic.  It is being lowered to a constant 0\n";
444    CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
445    break;
446  }
447
448  case Intrinsic::dbg_declare:
449    break;    // Simply strip out debugging intrinsics
450
451  case Intrinsic::eh_typeid_for:
452    // Return something different to eh_selector.
453    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
454    break;
455
456  case Intrinsic::annotation:
457  case Intrinsic::ptr_annotation:
458    // Just drop the annotation, but forward the value
459    CI->replaceAllUsesWith(CI->getOperand(0));
460    break;
461
462  case Intrinsic::var_annotation:
463    break;   // Strip out annotate intrinsic
464
465  case Intrinsic::memcpy: {
466    Type *IntPtr = DL.getIntPtrType(Context);
467    Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
468                                        /* isSigned */ false);
469    Value *Ops[3];
470    Ops[0] = CI->getArgOperand(0);
471    Ops[1] = CI->getArgOperand(1);
472    Ops[2] = Size;
473    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
474    break;
475  }
476  case Intrinsic::memmove: {
477    Type *IntPtr = DL.getIntPtrType(Context);
478    Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
479                                        /* isSigned */ false);
480    Value *Ops[3];
481    Ops[0] = CI->getArgOperand(0);
482    Ops[1] = CI->getArgOperand(1);
483    Ops[2] = Size;
484    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
485    break;
486  }
487  case Intrinsic::memset: {
488    Value *Op0 = CI->getArgOperand(0);
489    Type *IntPtr = DL.getIntPtrType(Op0->getType());
490    Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
491                                        /* isSigned */ false);
492    Value *Ops[3];
493    Ops[0] = Op0;
494    // Extend the amount to i32.
495    Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1),
496                                   Type::getInt32Ty(Context),
497                                   /* isSigned */ false);
498    Ops[2] = Size;
499    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
500    break;
501  }
502  case Intrinsic::sqrt: {
503    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
504    break;
505  }
506  case Intrinsic::log: {
507    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
508    break;
509  }
510  case Intrinsic::log2: {
511    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
512    break;
513  }
514  case Intrinsic::log10: {
515    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
516    break;
517  }
518  case Intrinsic::exp: {
519    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
520    break;
521  }
522  case Intrinsic::exp2: {
523    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
524    break;
525  }
526  case Intrinsic::pow: {
527    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
528    break;
529  }
530  case Intrinsic::flt_rounds:
531     // Lower to "round to the nearest"
532     if (!CI->getType()->isVoidTy())
533       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
534     break;
535  case Intrinsic::invariant_start:
536  case Intrinsic::lifetime_start:
537    // Discard region information.
538    CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
539    break;
540  case Intrinsic::invariant_end:
541  case Intrinsic::lifetime_end:
542    // Discard region information.
543    break;
544  }
545
546  assert(CI->use_empty() &&
547         "Lowering should have eliminated any uses of the intrinsic call!");
548  CI->eraseFromParent();
549}
550
551bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) {
552  // Verify this is a simple bswap.
553  if (CI->getNumArgOperands() != 1 ||
554      CI->getType() != CI->getArgOperand(0)->getType() ||
555      !CI->getType()->isIntegerTy())
556    return false;
557
558  IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
559  if (!Ty)
560    return false;
561
562  // Okay, we can do this xform, do so now.
563  Module *M = CI->getParent()->getParent()->getParent();
564  Constant *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty);
565
566  Value *Op = CI->getArgOperand(0);
567  Op = CallInst::Create(Int, Op, CI->getName(), CI);
568
569  CI->replaceAllUsesWith(Op);
570  CI->eraseFromParent();
571  return true;
572}
573