IntrinsicLowering.cpp revision 588e72db75649e8f9f79d73c24156c9611aeacf3 
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/IntrinsicLowering.h"
15#include "llvm/Constants.h"
16#include "llvm/DerivedTypes.h"
17#include "llvm/Module.h"
18#include "llvm/iOther.h"
19using namespace llvm;
20
21/// ReplaceCallWith - This function is used when we want to lower an intrinsic
22/// call to a call of an external function.  This handles hard cases such as
23/// when there was already a prototype for the external function, and if that
24/// prototype doesn't match the arguments we expect to pass in.
25template <class ArgIt>
26static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
27                                 ArgIt ArgBegin, ArgIt ArgEnd,
28                                 const Type *RetTy, Function *&FCache) {
29  if (!FCache) {
30    // If we haven't already looked up this function, check to see if the
31    // program already contains a function with this name.
32    Module *M = CI->getParent()->getParent()->getParent();
33    FCache = M->getNamedFunction(NewFn);
34    if (!FCache) {
35      // It doesn't already exist in the program, insert a new definition now.
36      std::vector<const Type *> ParamTys;
37      for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
38        ParamTys.push_back((*I)->getType());
39      FCache = M->getOrInsertFunction(NewFn,
40                                     FunctionType::get(RetTy, ParamTys, false));
41    }
42  }
43
44  const FunctionType *FT = FCache->getFunctionType();
45  std::vector<Value*> Operands;
46  unsigned ArgNo = 0;
47  for (ArgIt I = ArgBegin; I != ArgEnd && ArgNo != FT->getNumParams();
48       ++I, ++ArgNo) {
49    Value *Arg = *I;
50    if (Arg->getType() != FT->getParamType(ArgNo))
51      Arg = new CastInst(Arg, FT->getParamType(ArgNo), Arg->getName(), CI);
52    Operands.push_back(Arg);
53  }
54  // Pass nulls into any additional arguments...
55  for (; ArgNo != FT->getNumParams(); ++ArgNo)
56    Operands.push_back(Constant::getNullValue(FT->getParamType(ArgNo)));
57
58  std::string Name = CI->getName(); CI->setName("");
59  if (FT->getReturnType() == Type::VoidTy) Name.clear();
60  return new CallInst(FCache, Operands, Name, CI);
61}
62
63
64void DefaultIntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
65  Function *Callee = CI->getCalledFunction();
66  assert(Callee && "Cannot lower an indirect call!");
67
68  Module *M = Callee->getParent();
69
70  switch (Callee->getIntrinsicID()) {
71  case Intrinsic::not_intrinsic:
72    std::cerr << "Cannot lower a call to a non-intrinsic function '"
73              << Callee->getName() << "'!\n";
74    abort();
75  default:
76    std::cerr << "Error: Code generator does not support intrinsic function '"
77              << Callee->getName() << "'!\n";
78    abort();
79
80    // The setjmp/longjmp intrinsics should only exist in the code if it was
81    // never optimized (ie, right out of the CFE), or if it has been hacked on
82    // by the lowerinvoke pass.  In both cases, the right thing to do is to
83    // convert the call to an explicit setjmp or longjmp call.
84  case Intrinsic::setjmp:
85  case Intrinsic::sigsetjmp:
86    if (CI->getType() != Type::VoidTy)
87      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
88    break;
89
90  case Intrinsic::longjmp:
91  case Intrinsic::siglongjmp:
92    // Insert the call to abort
93    static Function *AbortFCache = 0;
94    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(), Type::VoidTy,
95                    AbortFCache);
96    break;
97
98  case Intrinsic::returnaddress:
99  case Intrinsic::frameaddress:
100    std::cerr << "WARNING: this target does not support the llvm."
101              << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
102                  "return" : "frame") << "address intrinsic.\n";
103    CI->replaceAllUsesWith(ConstantPointerNull::get(
104                                            cast<PointerType>(CI->getType())));
105    break;
106
107  case Intrinsic::dbg_stoppoint:
108  case Intrinsic::dbg_region_start:
109  case Intrinsic::dbg_region_end:
110  case Intrinsic::dbg_declare:
111  case Intrinsic::dbg_func_start:
112    if (CI->getType() != Type::VoidTy)
113      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
114    break;    // Simply strip out debugging intrinsics
115
116  case Intrinsic::memcpy:
117    // The memcpy intrinsic take an extra alignment argument that the memcpy
118    // libc function does not.
119    static Function *MemcpyFCache = 0;
120    ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
121                    (*(CI->op_begin()+1))->getType(), MemcpyFCache);
122    break;
123  case Intrinsic::memmove:
124    // The memmove intrinsic take an extra alignment argument that the memmove
125    // libc function does not.
126    static Function *MemmoveFCache = 0;
127    ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
128                    (*(CI->op_begin()+1))->getType(), MemmoveFCache);
129    break;
130  case Intrinsic::memset:
131    // The memset intrinsic take an extra alignment argument that the memset
132    // libc function does not.
133    static Function *MemsetFCache = 0;
134    ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
135                    (*(CI->op_begin()+1))->getType(), MemsetFCache);
136    break;
137  }
138
139  assert(CI->use_empty() &&
140         "Lowering should have eliminated any uses of the intrinsic call!");
141  CI->getParent()->getInstList().erase(CI);
142}
143