IntrinsicLowering.cpp revision edf128a7fa90f2b0b7ee24741a04a7ae1ecd6f7e 
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 <iostream>
20
21using namespace llvm;
22
23template <class ArgIt>
24static Function *EnsureFunctionExists(Module &M, const char *Name,
25                                      ArgIt ArgBegin, ArgIt ArgEnd,
26                                      const Type *RetTy) {
27  if (Function *F = M.getNamedFunction(Name)) return F;
28  // It doesn't already exist in the program, insert a new definition now.
29  std::vector<const Type *> ParamTys;
30  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
31    ParamTys.push_back(I->getType());
32  return M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
33}
34
35/// ReplaceCallWith - This function is used when we want to lower an intrinsic
36/// call to a call of an external function.  This handles hard cases such as
37/// when there was already a prototype for the external function, and if that
38/// prototype doesn't match the arguments we expect to pass in.
39template <class ArgIt>
40static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
41                                 ArgIt ArgBegin, ArgIt ArgEnd,
42                                 const Type *RetTy, Function *&FCache) {
43  if (!FCache) {
44    // If we haven't already looked up this function, check to see if the
45    // program already contains a function with this name.
46    Module *M = CI->getParent()->getParent()->getParent();
47    FCache = M->getNamedFunction(NewFn);
48    if (!FCache) {
49      // It doesn't already exist in the program, insert a new definition now.
50      std::vector<const Type *> ParamTys;
51      for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
52        ParamTys.push_back((*I)->getType());
53      FCache = M->getOrInsertFunction(NewFn,
54                                     FunctionType::get(RetTy, ParamTys, false));
55    }
56   }
57
58  const FunctionType *FT = FCache->getFunctionType();
59  std::vector<Value*> Operands;
60  unsigned ArgNo = 0;
61  for (ArgIt I = ArgBegin; I != ArgEnd && ArgNo != FT->getNumParams();
62       ++I, ++ArgNo) {
63    Value *Arg = *I;
64    if (Arg->getType() != FT->getParamType(ArgNo))
65      Arg = new CastInst(Arg, FT->getParamType(ArgNo), Arg->getName(), CI);
66    Operands.push_back(Arg);
67  }
68  // Pass nulls into any additional arguments...
69  for (; ArgNo != FT->getNumParams(); ++ArgNo)
70    Operands.push_back(Constant::getNullValue(FT->getParamType(ArgNo)));
71
72  std::string Name = CI->getName(); CI->setName("");
73  if (FT->getReturnType() == Type::VoidTy) Name.clear();
74  CallInst *NewCI = new CallInst(FCache, Operands, Name, CI);
75  if (!CI->use_empty()) {
76    Value *V = NewCI;
77    if (CI->getType() != NewCI->getType())
78      V = new CastInst(NewCI, CI->getType(), Name, CI);
79    CI->replaceAllUsesWith(V);
80  }
81  return NewCI;
82}
83
84void DefaultIntrinsicLowering::AddPrototypes(Module &M) {
85  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
86    if (I->isExternal() && !I->use_empty())
87      switch (I->getIntrinsicID()) {
88      default: break;
89      case Intrinsic::setjmp:
90        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(), Type::IntTy);
91        break;
92      case Intrinsic::longjmp:
93        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),Type::VoidTy);
94        break;
95      case Intrinsic::siglongjmp:
96        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(), Type::VoidTy);
97        break;
98      case Intrinsic::memcpy:
99        EnsureFunctionExists(M, "memcpy", I->arg_begin(), --I->arg_end(),
100                             I->arg_begin()->getType());
101        break;
102      case Intrinsic::memmove:
103        EnsureFunctionExists(M, "memmove", I->arg_begin(), --I->arg_end(),
104                             I->arg_begin()->getType());
105        break;
106      case Intrinsic::memset:
107        EnsureFunctionExists(M, "memset", I->arg_begin(), --I->arg_end(),
108                             I->arg_begin()->getType());
109        break;
110      case Intrinsic::isunordered:
111        EnsureFunctionExists(M, "isunordered", I->arg_begin(), I->arg_end(), Type::BoolTy);
112        break;
113      }
114
115}
116
117void DefaultIntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
118  Function *Callee = CI->getCalledFunction();
119  assert(Callee && "Cannot lower an indirect call!");
120
121  switch (Callee->getIntrinsicID()) {
122  case Intrinsic::not_intrinsic:
123    std::cerr << "Cannot lower a call to a non-intrinsic function '"
124              << Callee->getName() << "'!\n";
125    abort();
126  default:
127    std::cerr << "Error: Code generator does not support intrinsic function '"
128              << Callee->getName() << "'!\n";
129    abort();
130
131    // The setjmp/longjmp intrinsics should only exist in the code if it was
132    // never optimized (ie, right out of the CFE), or if it has been hacked on
133    // by the lowerinvoke pass.  In both cases, the right thing to do is to
134    // convert the call to an explicit setjmp or longjmp call.
135  case Intrinsic::setjmp: {
136    static Function *SetjmpFCache = 0;
137    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin()+1, CI->op_end(),
138                               Type::IntTy, SetjmpFCache);
139    if (CI->getType() != Type::VoidTy)
140      CI->replaceAllUsesWith(V);
141    break;
142  }
143  case Intrinsic::sigsetjmp:
144     if (CI->getType() != Type::VoidTy)
145       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
146     break;
147
148  case Intrinsic::longjmp: {
149    static Function *LongjmpFCache = 0;
150    ReplaceCallWith("longjmp", CI, CI->op_begin()+1, CI->op_end(),
151                    Type::VoidTy, LongjmpFCache);
152    break;
153  }
154
155  case Intrinsic::siglongjmp: {
156    // Insert the call to abort
157    static Function *AbortFCache = 0;
158    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(), Type::VoidTy,
159                    AbortFCache);
160    break;
161  }
162
163  case Intrinsic::returnaddress:
164  case Intrinsic::frameaddress:
165    std::cerr << "WARNING: this target does not support the llvm."
166              << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
167                  "return" : "frame") << "address intrinsic.\n";
168    CI->replaceAllUsesWith(ConstantPointerNull::get(
169                                            cast<PointerType>(CI->getType())));
170    break;
171
172  case Intrinsic::prefetch:
173    break;    // Simply strip out prefetches on unsupported architectures
174
175  case Intrinsic::pcmarker:
176    break;    // Simply strip out pcmarker on unsupported architectures
177
178  case Intrinsic::dbg_stoppoint:
179  case Intrinsic::dbg_region_start:
180  case Intrinsic::dbg_region_end:
181  case Intrinsic::dbg_declare:
182  case Intrinsic::dbg_func_start:
183    if (CI->getType() != Type::VoidTy)
184      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
185    break;    // Simply strip out debugging intrinsics
186
187  case Intrinsic::memcpy: {
188    // The memcpy intrinsic take an extra alignment argument that the memcpy
189    // libc function does not.
190    static Function *MemcpyFCache = 0;
191    ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
192                    (*(CI->op_begin()+1))->getType(), MemcpyFCache);
193    break;
194  }
195  case Intrinsic::memmove: {
196    // The memmove intrinsic take an extra alignment argument that the memmove
197    // libc function does not.
198    static Function *MemmoveFCache = 0;
199    ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
200                    (*(CI->op_begin()+1))->getType(), MemmoveFCache);
201    break;
202  }
203  case Intrinsic::memset: {
204    // The memset intrinsic take an extra alignment argument that the memset
205    // libc function does not.
206    static Function *MemsetFCache = 0;
207    ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
208                    (*(CI->op_begin()+1))->getType(), MemsetFCache);
209    break;
210  }
211  case Intrinsic::isunordered: {
212    Value *L = CI->getOperand(1);
213    Value *R = CI->getOperand(2);
214
215    Value *LIsNan = new SetCondInst(Instruction::SetNE, L, L, "LIsNan", CI);
216    Value *RIsNan = new SetCondInst(Instruction::SetNE, R, R, "RIsNan", CI);
217    CI->replaceAllUsesWith(
218      BinaryOperator::create(Instruction::Or, LIsNan, RIsNan,
219                             "isunordered", CI));
220    break;
221  }
222  }
223
224  assert(CI->use_empty() &&
225         "Lowering should have eliminated any uses of the intrinsic call!");
226  CI->getParent()->getInstList().erase(CI);
227}
228