1 //===-- IntrinsicLowering.cpp - Intrinsic Lowering default implementation -===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the IntrinsicLowering class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/CodeGen/IntrinsicLowering.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include "llvm/IR/CallSite.h"
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/DerivedTypes.h"
19 #include "llvm/IR/IRBuilder.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/IR/Type.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/raw_ostream.h"
24 using namespace llvm;
25 
26 template <class ArgIt>
27 static void EnsureFunctionExists(Module &M, const char *Name,
28                                  ArgIt ArgBegin, ArgIt ArgEnd,
29                                  Type *RetTy) {
30   // Insert a correctly-typed definition now.
31   std::vector<Type *> ParamTys;
32   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
33     ParamTys.push_back(I->getType());
34   M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
35 }
36 
37 static void EnsureFPIntrinsicsExist(Module &M, Function &Fn,
38                                     const char *FName,
39                                     const char *DName, const char *LDName) {
40   // Insert definitions for all the floating point types.
41   switch((int)Fn.arg_begin()->getType()->getTypeID()) {
42   case Type::FloatTyID:
43     EnsureFunctionExists(M, FName, Fn.arg_begin(), Fn.arg_end(),
44                          Type::getFloatTy(M.getContext()));
45     break;
46   case Type::DoubleTyID:
47     EnsureFunctionExists(M, DName, Fn.arg_begin(), Fn.arg_end(),
48                          Type::getDoubleTy(M.getContext()));
49     break;
50   case Type::X86_FP80TyID:
51   case Type::FP128TyID:
52   case Type::PPC_FP128TyID:
53     EnsureFunctionExists(M, LDName, Fn.arg_begin(), Fn.arg_end(),
54                          Fn.arg_begin()->getType());
55     break;
56   }
57 }
58 
59 /// This function is used when we want to lower an intrinsic call to a call of
60 /// an external function. This handles hard cases such as when there was already
61 /// a prototype for the external function, but that prototype doesn't match the
62 /// arguments we expect to pass in.
63 template <class ArgIt>
64 static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
65                                  ArgIt ArgBegin, ArgIt ArgEnd,
66                                  Type *RetTy) {
67   // If we haven't already looked up this function, check to see if the
68   // program already contains a function with this name.
69   Module *M = CI->getModule();
70   // Get or insert the definition now.
71   std::vector<Type *> ParamTys;
72   for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
73     ParamTys.push_back((*I)->getType());
74   Constant* FCache = M->getOrInsertFunction(NewFn,
75                                   FunctionType::get(RetTy, ParamTys, false));
76 
77   IRBuilder<> Builder(CI->getParent(), CI->getIterator());
78   SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
79   CallInst *NewCI = Builder.CreateCall(FCache, Args);
80   NewCI->setName(CI->getName());
81   if (!CI->use_empty())
82     CI->replaceAllUsesWith(NewCI);
83   return NewCI;
84 }
85 
86 // VisualStudio defines setjmp as _setjmp
87 #if defined(_MSC_VER) && defined(setjmp) && \
88                          !defined(setjmp_undefined_for_msvc)
89 #  pragma push_macro("setjmp")
90 #  undef setjmp
91 #  define setjmp_undefined_for_msvc
92 #endif
93 
94 void IntrinsicLowering::AddPrototypes(Module &M) {
95   LLVMContext &Context = M.getContext();
96   for (auto &F : M)
97     if (F.isDeclaration() && !F.use_empty())
98       switch (F.getIntrinsicID()) {
99       default: break;
100       case Intrinsic::setjmp:
101         EnsureFunctionExists(M, "setjmp", F.arg_begin(), F.arg_end(),
102                              Type::getInt32Ty(M.getContext()));
103         break;
104       case Intrinsic::longjmp:
105         EnsureFunctionExists(M, "longjmp", F.arg_begin(), F.arg_end(),
106                              Type::getVoidTy(M.getContext()));
107         break;
108       case Intrinsic::siglongjmp:
109         EnsureFunctionExists(M, "abort", F.arg_end(), F.arg_end(),
110                              Type::getVoidTy(M.getContext()));
111         break;
112       case Intrinsic::memcpy:
113         M.getOrInsertFunction("memcpy",
114           Type::getInt8PtrTy(Context),
115                               Type::getInt8PtrTy(Context),
116                               Type::getInt8PtrTy(Context),
117                               DL.getIntPtrType(Context));
118         break;
119       case Intrinsic::memmove:
120         M.getOrInsertFunction("memmove",
121           Type::getInt8PtrTy(Context),
122                               Type::getInt8PtrTy(Context),
123                               Type::getInt8PtrTy(Context),
124                               DL.getIntPtrType(Context));
125         break;
126       case Intrinsic::memset:
127         M.getOrInsertFunction("memset",
128           Type::getInt8PtrTy(Context),
129                               Type::getInt8PtrTy(Context),
130                               Type::getInt32Ty(M.getContext()),
131                               DL.getIntPtrType(Context));
132         break;
133       case Intrinsic::sqrt:
134         EnsureFPIntrinsicsExist(M, F, "sqrtf", "sqrt", "sqrtl");
135         break;
136       case Intrinsic::sin:
137         EnsureFPIntrinsicsExist(M, F, "sinf", "sin", "sinl");
138         break;
139       case Intrinsic::cos:
140         EnsureFPIntrinsicsExist(M, F, "cosf", "cos", "cosl");
141         break;
142       case Intrinsic::pow:
143         EnsureFPIntrinsicsExist(M, F, "powf", "pow", "powl");
144         break;
145       case Intrinsic::log:
146         EnsureFPIntrinsicsExist(M, F, "logf", "log", "logl");
147         break;
148       case Intrinsic::log2:
149         EnsureFPIntrinsicsExist(M, F, "log2f", "log2", "log2l");
150         break;
151       case Intrinsic::log10:
152         EnsureFPIntrinsicsExist(M, F, "log10f", "log10", "log10l");
153         break;
154       case Intrinsic::exp:
155         EnsureFPIntrinsicsExist(M, F, "expf", "exp", "expl");
156         break;
157       case Intrinsic::exp2:
158         EnsureFPIntrinsicsExist(M, F, "exp2f", "exp2", "exp2l");
159         break;
160       }
161 }
162 
163 /// Emit the code to lower bswap of V before the specified instruction IP.
164 static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
165   assert(V->getType()->isIntOrIntVectorTy() && "Can't bswap a non-integer type!");
166 
167   unsigned BitSize = V->getType()->getScalarSizeInBits();
168 
169   IRBuilder<> Builder(IP);
170 
171   switch(BitSize) {
172   default: llvm_unreachable("Unhandled type size of value to byteswap!");
173   case 16: {
174     Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
175                                     "bswap.2");
176     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
177                                      "bswap.1");
178     V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
179     break;
180   }
181   case 32: {
182     Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
183                                     "bswap.4");
184     Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
185                                     "bswap.3");
186     Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
187                                      "bswap.2");
188     Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
189                                      "bswap.1");
190     Tmp3 = Builder.CreateAnd(Tmp3,
191                          ConstantInt::get(V->getType(), 0xFF0000),
192                              "bswap.and3");
193     Tmp2 = Builder.CreateAnd(Tmp2,
194                            ConstantInt::get(V->getType(), 0xFF00),
195                              "bswap.and2");
196     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
197     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
198     V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
199     break;
200   }
201   case 64: {
202     Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
203                                     "bswap.8");
204     Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
205                                     "bswap.7");
206     Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
207                                     "bswap.6");
208     Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
209                                     "bswap.5");
210     Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
211                                      "bswap.4");
212     Value* Tmp3 = Builder.CreateLShr(V,
213                                      ConstantInt::get(V->getType(), 24),
214                                      "bswap.3");
215     Value* Tmp2 = Builder.CreateLShr(V,
216                                      ConstantInt::get(V->getType(), 40),
217                                      "bswap.2");
218     Value* Tmp1 = Builder.CreateLShr(V,
219                                      ConstantInt::get(V->getType(), 56),
220                                      "bswap.1");
221     Tmp7 = Builder.CreateAnd(Tmp7,
222                              ConstantInt::get(V->getType(),
223                                               0xFF000000000000ULL),
224                              "bswap.and7");
225     Tmp6 = Builder.CreateAnd(Tmp6,
226                              ConstantInt::get(V->getType(),
227                                               0xFF0000000000ULL),
228                              "bswap.and6");
229     Tmp5 = Builder.CreateAnd(Tmp5,
230                         ConstantInt::get(V->getType(),
231                              0xFF00000000ULL),
232                              "bswap.and5");
233     Tmp4 = Builder.CreateAnd(Tmp4,
234                         ConstantInt::get(V->getType(),
235                              0xFF000000ULL),
236                              "bswap.and4");
237     Tmp3 = Builder.CreateAnd(Tmp3,
238                              ConstantInt::get(V->getType(),
239                              0xFF0000ULL),
240                              "bswap.and3");
241     Tmp2 = Builder.CreateAnd(Tmp2,
242                              ConstantInt::get(V->getType(),
243                              0xFF00ULL),
244                              "bswap.and2");
245     Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
246     Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
247     Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
248     Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
249     Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
250     Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
251     V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
252     break;
253   }
254   }
255   return V;
256 }
257 
258 /// Emit the code to lower ctpop of V before the specified instruction IP.
259 static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
260   assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");
261 
262   static const uint64_t MaskValues[6] = {
263     0x5555555555555555ULL, 0x3333333333333333ULL,
264     0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
265     0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
266   };
267 
268   IRBuilder<> Builder(IP);
269 
270   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
271   unsigned WordSize = (BitSize + 63) / 64;
272   Value *Count = ConstantInt::get(V->getType(), 0);
273 
274   for (unsigned n = 0; n < WordSize; ++n) {
275     Value *PartValue = V;
276     for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
277          i <<= 1, ++ct) {
278       Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
279       Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
280       Value *VShift = Builder.CreateLShr(PartValue,
281                                         ConstantInt::get(V->getType(), i),
282                                          "ctpop.sh");
283       Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
284       PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
285     }
286     Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
287     if (BitSize > 64) {
288       V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
289                              "ctpop.part.sh");
290       BitSize -= 64;
291     }
292   }
293 
294   return Count;
295 }
296 
297 /// Emit the code to lower ctlz of V before the specified instruction IP.
298 static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
299 
300   IRBuilder<> Builder(IP);
301 
302   unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
303   for (unsigned i = 1; i < BitSize; i <<= 1) {
304     Value *ShVal = ConstantInt::get(V->getType(), i);
305     ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
306     V = Builder.CreateOr(V, ShVal, "ctlz.step");
307   }
308 
309   V = Builder.CreateNot(V);
310   return LowerCTPOP(Context, V, IP);
311 }
312 
313 static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
314                                        const char *Dname,
315                                        const char *LDname) {
316   CallSite CS(CI);
317   switch (CI->getArgOperand(0)->getType()->getTypeID()) {
318   default: llvm_unreachable("Invalid type in intrinsic");
319   case Type::FloatTyID:
320     ReplaceCallWith(Fname, CI, CS.arg_begin(), CS.arg_end(),
321                   Type::getFloatTy(CI->getContext()));
322     break;
323   case Type::DoubleTyID:
324     ReplaceCallWith(Dname, CI, CS.arg_begin(), CS.arg_end(),
325                   Type::getDoubleTy(CI->getContext()));
326     break;
327   case Type::X86_FP80TyID:
328   case Type::FP128TyID:
329   case Type::PPC_FP128TyID:
330     ReplaceCallWith(LDname, CI, CS.arg_begin(), CS.arg_end(),
331                   CI->getArgOperand(0)->getType());
332     break;
333   }
334 }
335 
336 void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
337   IRBuilder<> Builder(CI);
338   LLVMContext &Context = CI->getContext();
339 
340   const Function *Callee = CI->getCalledFunction();
341   assert(Callee && "Cannot lower an indirect call!");
342 
343   CallSite CS(CI);
344   switch (Callee->getIntrinsicID()) {
345   case Intrinsic::not_intrinsic:
346     report_fatal_error("Cannot lower a call to a non-intrinsic function '"+
347                       Callee->getName() + "'!");
348   default:
349     report_fatal_error("Code generator does not support intrinsic function '"+
350                       Callee->getName()+"'!");
351 
352   case Intrinsic::expect: {
353     // Just replace __builtin_expect(exp, c) with EXP.
354     Value *V = CI->getArgOperand(0);
355     CI->replaceAllUsesWith(V);
356     break;
357   }
358 
359     // The setjmp/longjmp intrinsics should only exist in the code if it was
360     // never optimized (ie, right out of the CFE), or if it has been hacked on
361     // by the lowerinvoke pass.  In both cases, the right thing to do is to
362     // convert the call to an explicit setjmp or longjmp call.
363   case Intrinsic::setjmp: {
364     Value *V = ReplaceCallWith("setjmp", CI, CS.arg_begin(), CS.arg_end(),
365                                Type::getInt32Ty(Context));
366     if (!CI->getType()->isVoidTy())
367       CI->replaceAllUsesWith(V);
368     break;
369   }
370   case Intrinsic::sigsetjmp:
371      if (!CI->getType()->isVoidTy())
372        CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
373      break;
374 
375   case Intrinsic::longjmp: {
376     ReplaceCallWith("longjmp", CI, CS.arg_begin(), CS.arg_end(),
377                     Type::getVoidTy(Context));
378     break;
379   }
380 
381   case Intrinsic::siglongjmp: {
382     // Insert the call to abort
383     ReplaceCallWith("abort", CI, CS.arg_end(), CS.arg_end(),
384                     Type::getVoidTy(Context));
385     break;
386   }
387   case Intrinsic::ctpop:
388     CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getArgOperand(0), CI));
389     break;
390 
391   case Intrinsic::bswap:
392     CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getArgOperand(0), CI));
393     break;
394 
395   case Intrinsic::ctlz:
396     CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getArgOperand(0), CI));
397     break;
398 
399   case Intrinsic::cttz: {
400     // cttz(x) -> ctpop(~X & (X-1))
401     Value *Src = CI->getArgOperand(0);
402     Value *NotSrc = Builder.CreateNot(Src);
403     NotSrc->setName(Src->getName() + ".not");
404     Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
405     SrcM1 = Builder.CreateSub(Src, SrcM1);
406     Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
407     CI->replaceAllUsesWith(Src);
408     break;
409   }
410 
411   case Intrinsic::stacksave:
412   case Intrinsic::stackrestore: {
413     if (!Warned)
414       errs() << "WARNING: this target does not support the llvm.stack"
415              << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
416                "save" : "restore") << " intrinsic.\n";
417     Warned = true;
418     if (Callee->getIntrinsicID() == Intrinsic::stacksave)
419       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
420     break;
421   }
422 
423   case Intrinsic::get_dynamic_area_offset:
424     errs() << "WARNING: this target does not support the custom llvm.get."
425               "dynamic.area.offset.  It is being lowered to a constant 0\n";
426     // Just lower it to a constant 0 because for most targets
427     // @llvm.get.dynamic.area.offset is lowered to zero.
428     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 0));
429     break;
430   case Intrinsic::returnaddress:
431   case Intrinsic::frameaddress:
432     errs() << "WARNING: this target does not support the llvm."
433            << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
434              "return" : "frame") << "address intrinsic.\n";
435     CI->replaceAllUsesWith(
436         ConstantPointerNull::get(cast<PointerType>(CI->getType())));
437     break;
438   case Intrinsic::addressofreturnaddress:
439     errs() << "WARNING: this target does not support the "
440               "llvm.addressofreturnaddress intrinsic.\n";
441     CI->replaceAllUsesWith(
442         ConstantPointerNull::get(cast<PointerType>(CI->getType())));
443     break;
444 
445   case Intrinsic::prefetch:
446     break;    // Simply strip out prefetches on unsupported architectures
447 
448   case Intrinsic::pcmarker:
449     break;    // Simply strip out pcmarker on unsupported architectures
450   case Intrinsic::readcyclecounter: {
451     errs() << "WARNING: this target does not support the llvm.readcyclecoun"
452            << "ter intrinsic.  It is being lowered to a constant 0\n";
453     CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
454     break;
455   }
456 
457   case Intrinsic::dbg_declare:
458   case Intrinsic::dbg_label:
459     break;    // Simply strip out debugging intrinsics
460 
461   case Intrinsic::eh_typeid_for:
462     // Return something different to eh_selector.
463     CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
464     break;
465 
466   case Intrinsic::annotation:
467   case Intrinsic::ptr_annotation:
468     // Just drop the annotation, but forward the value
469     CI->replaceAllUsesWith(CI->getOperand(0));
470     break;
471 
472   case Intrinsic::assume:
473   case Intrinsic::var_annotation:
474     break;   // Strip out these intrinsics
475 
476   case Intrinsic::memcpy: {
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("memcpy", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
485     break;
486   }
487   case Intrinsic::memmove: {
488     Type *IntPtr = DL.getIntPtrType(Context);
489     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
490                                         /* isSigned */ false);
491     Value *Ops[3];
492     Ops[0] = CI->getArgOperand(0);
493     Ops[1] = CI->getArgOperand(1);
494     Ops[2] = Size;
495     ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
496     break;
497   }
498   case Intrinsic::memset: {
499     Value *Op0 = CI->getArgOperand(0);
500     Type *IntPtr = DL.getIntPtrType(Op0->getType());
501     Value *Size = Builder.CreateIntCast(CI->getArgOperand(2), IntPtr,
502                                         /* isSigned */ false);
503     Value *Ops[3];
504     Ops[0] = Op0;
505     // Extend the amount to i32.
506     Ops[1] = Builder.CreateIntCast(CI->getArgOperand(1),
507                                    Type::getInt32Ty(Context),
508                                    /* isSigned */ false);
509     Ops[2] = Size;
510     ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getArgOperand(0)->getType());
511     break;
512   }
513   case Intrinsic::sqrt: {
514     ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
515     break;
516   }
517   case Intrinsic::log: {
518     ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
519     break;
520   }
521   case Intrinsic::log2: {
522     ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
523     break;
524   }
525   case Intrinsic::log10: {
526     ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
527     break;
528   }
529   case Intrinsic::exp: {
530     ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
531     break;
532   }
533   case Intrinsic::exp2: {
534     ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
535     break;
536   }
537   case Intrinsic::pow: {
538     ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
539     break;
540   }
541   case Intrinsic::sin: {
542     ReplaceFPIntrinsicWithCall(CI, "sinf", "sin", "sinl");
543     break;
544   }
545   case Intrinsic::cos: {
546     ReplaceFPIntrinsicWithCall(CI, "cosf", "cos", "cosl");
547     break;
548   }
549   case Intrinsic::floor: {
550     ReplaceFPIntrinsicWithCall(CI, "floorf", "floor", "floorl");
551     break;
552   }
553   case Intrinsic::ceil: {
554     ReplaceFPIntrinsicWithCall(CI, "ceilf", "ceil", "ceill");
555     break;
556   }
557   case Intrinsic::trunc: {
558     ReplaceFPIntrinsicWithCall(CI, "truncf", "trunc", "truncl");
559     break;
560   }
561   case Intrinsic::round: {
562     ReplaceFPIntrinsicWithCall(CI, "roundf", "round", "roundl");
563     break;
564   }
565   case Intrinsic::copysign: {
566     ReplaceFPIntrinsicWithCall(CI, "copysignf", "copysign", "copysignl");
567     break;
568   }
569   case Intrinsic::flt_rounds:
570      // Lower to "round to the nearest"
571      if (!CI->getType()->isVoidTy())
572        CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
573      break;
574   case Intrinsic::invariant_start:
575   case Intrinsic::lifetime_start:
576     // Discard region information.
577     CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
578     break;
579   case Intrinsic::invariant_end:
580   case Intrinsic::lifetime_end:
581     // Discard region information.
582     break;
583   }
584 
585   assert(CI->use_empty() &&
586          "Lowering should have eliminated any uses of the intrinsic call!");
587   CI->eraseFromParent();
588 }
589 
590 bool IntrinsicLowering::LowerToByteSwap(CallInst *CI) {
591   // Verify this is a simple bswap.
592   if (CI->getNumArgOperands() != 1 ||
593       CI->getType() != CI->getArgOperand(0)->getType() ||
594       !CI->getType()->isIntegerTy())
595     return false;
596 
597   IntegerType *Ty = dyn_cast<IntegerType>(CI->getType());
598   if (!Ty)
599     return false;
600 
601   // Okay, we can do this xform, do so now.
602   Module *M = CI->getModule();
603   Constant *Int = Intrinsic::getDeclaration(M, Intrinsic::bswap, Ty);
604 
605   Value *Op = CI->getArgOperand(0);
606   Op = CallInst::Create(Int, Op, CI->getName(), CI);
607 
608   CI->replaceAllUsesWith(Op);
609   CI->eraseFromParent();
610   return true;
611 }
612