IntrinsicLowering.cpp revision b76efb71d41dc1ae33e47d5d9ef79df25cde0b5d 
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 IntrinsicLowering class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Constants.h"
15#include "llvm/DerivedTypes.h"
16#include "llvm/Module.h"
17#include "llvm/Instructions.h"
18#include "llvm/Type.h"
19#include "llvm/CodeGen/IntrinsicLowering.h"
20#include "llvm/Support/Streams.h"
21using namespace llvm;
22
23template <class ArgIt>
24static void EnsureFunctionExists(Module &M, const char *Name,
25                                 ArgIt ArgBegin, ArgIt ArgEnd,
26                                 const Type *RetTy) {
27  // Insert a correctly-typed definition now.
28  std::vector<const Type *> ParamTys;
29  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
30    ParamTys.push_back(I->getType());
31  M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
32}
33
34/// ReplaceCallWith - This function is used when we want to lower an intrinsic
35/// call to a call of an external function.  This handles hard cases such as
36/// when there was already a prototype for the external function, and if that
37/// prototype doesn't match the arguments we expect to pass in.
38template <class ArgIt>
39static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
40                                 ArgIt ArgBegin, ArgIt ArgEnd,
41                                 const Type *RetTy, Constant *&FCache) {
42  if (!FCache) {
43    // If we haven't already looked up this function, check to see if the
44    // program already contains a function with this name.
45    Module *M = CI->getParent()->getParent()->getParent();
46    // Get or insert the definition now.
47    std::vector<const Type *> ParamTys;
48    for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
49      ParamTys.push_back((*I)->getType());
50    FCache = M->getOrInsertFunction(NewFn,
51                                    FunctionType::get(RetTy, ParamTys, false));
52  }
53
54  std::vector<Value*> Operands(ArgBegin, ArgEnd);
55  CallInst *NewCI = new CallInst(FCache, Operands, CI->getName(), CI);
56  if (!CI->use_empty())
57    CI->replaceAllUsesWith(NewCI);
58  return NewCI;
59}
60
61void IntrinsicLowering::AddPrototypes(Module &M) {
62  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
63    if (I->isExternal() && !I->use_empty())
64      switch (I->getIntrinsicID()) {
65      default: break;
66      case Intrinsic::setjmp:
67        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
68                             Type::Int32Ty);
69        break;
70      case Intrinsic::longjmp:
71        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
72                             Type::VoidTy);
73        break;
74      case Intrinsic::siglongjmp:
75        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
76                             Type::VoidTy);
77        break;
78      case Intrinsic::memcpy_i32:
79      case Intrinsic::memcpy_i64:
80        EnsureFunctionExists(M, "memcpy", I->arg_begin(), --I->arg_end(),
81                             I->arg_begin()->getType());
82        break;
83      case Intrinsic::memmove_i32:
84      case Intrinsic::memmove_i64:
85        EnsureFunctionExists(M, "memmove", I->arg_begin(), --I->arg_end(),
86                             I->arg_begin()->getType());
87        break;
88      case Intrinsic::memset_i32:
89      case Intrinsic::memset_i64:
90        M.getOrInsertFunction("memset", PointerType::get(Type::Int8Ty),
91                              PointerType::get(Type::Int8Ty),
92                              Type::Int32Ty, (--(--I->arg_end()))->getType(),
93                              (Type *)0);
94        break;
95      case Intrinsic::isunordered_f32:
96      case Intrinsic::isunordered_f64:
97        EnsureFunctionExists(M, "isunordered", I->arg_begin(), I->arg_end(),
98                             Type::BoolTy);
99        break;
100      case Intrinsic::sqrt_f32:
101      case Intrinsic::sqrt_f64:
102        if(I->arg_begin()->getType() == Type::FloatTy)
103          EnsureFunctionExists(M, "sqrtf", I->arg_begin(), I->arg_end(),
104                               Type::FloatTy);
105        else
106          EnsureFunctionExists(M, "sqrt", I->arg_begin(), I->arg_end(),
107                               Type::DoubleTy);
108        break;
109      }
110}
111
112/// LowerBSWAP - Emit the code to lower bswap of V before the specified
113/// instruction IP.
114static Value *LowerBSWAP(Value *V, Instruction *IP) {
115  assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
116
117  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
118
119  switch(BitSize) {
120  default: assert(0 && "Unhandled type size of value to byteswap!");
121  case 16: {
122    Value *Tmp1 = new ShiftInst(Instruction::Shl, V,
123                                ConstantInt::get(Type::Int8Ty,8),"bswap.2",IP);
124    Value *Tmp2 = new ShiftInst(Instruction::LShr, V,
125                                ConstantInt::get(Type::Int8Ty,8),"bswap.1",IP);
126    V = BinaryOperator::createOr(Tmp1, Tmp2, "bswap.i16", IP);
127    break;
128  }
129  case 32: {
130    Value *Tmp4 = new ShiftInst(Instruction::Shl, V,
131                              ConstantInt::get(Type::Int8Ty,24),"bswap.4", IP);
132    Value *Tmp3 = new ShiftInst(Instruction::Shl, V,
133                              ConstantInt::get(Type::Int8Ty,8),"bswap.3",IP);
134    Value *Tmp2 = new ShiftInst(Instruction::LShr, V,
135                              ConstantInt::get(Type::Int8Ty,8),"bswap.2",IP);
136    Value *Tmp1 = new ShiftInst(Instruction::LShr, V,
137                              ConstantInt::get(Type::Int8Ty,24),"bswap.1", IP);
138    Tmp3 = BinaryOperator::createAnd(Tmp3,
139                                     ConstantInt::get(Type::Int32Ty, 0xFF0000),
140                                     "bswap.and3", IP);
141    Tmp2 = BinaryOperator::createAnd(Tmp2,
142                                     ConstantInt::get(Type::Int32Ty, 0xFF00),
143                                     "bswap.and2", IP);
144    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or1", IP);
145    Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or2", IP);
146    V = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.i32", IP);
147    break;
148  }
149  case 64: {
150    Value *Tmp8 = new ShiftInst(Instruction::Shl, V,
151                              ConstantInt::get(Type::Int8Ty,56),"bswap.8", IP);
152    Value *Tmp7 = new ShiftInst(Instruction::Shl, V,
153                              ConstantInt::get(Type::Int8Ty,40),"bswap.7", IP);
154    Value *Tmp6 = new ShiftInst(Instruction::Shl, V,
155                              ConstantInt::get(Type::Int8Ty,24),"bswap.6", IP);
156    Value *Tmp5 = new ShiftInst(Instruction::Shl, V,
157                              ConstantInt::get(Type::Int8Ty,8),"bswap.5", IP);
158    Value* Tmp4 = new ShiftInst(Instruction::LShr, V,
159                              ConstantInt::get(Type::Int8Ty,8),"bswap.4", IP);
160    Value* Tmp3 = new ShiftInst(Instruction::LShr, V,
161                              ConstantInt::get(Type::Int8Ty,24),"bswap.3", IP);
162    Value* Tmp2 = new ShiftInst(Instruction::LShr, V,
163                              ConstantInt::get(Type::Int8Ty,40),"bswap.2", IP);
164    Value* Tmp1 = new ShiftInst(Instruction::LShr, V,
165                              ConstantInt::get(Type::Int8Ty,56),"bswap.1", IP);
166    Tmp7 = BinaryOperator::createAnd(Tmp7,
167                             ConstantInt::get(Type::Int64Ty,
168                               0xFF000000000000ULL),
169                             "bswap.and7", IP);
170    Tmp6 = BinaryOperator::createAnd(Tmp6,
171                             ConstantInt::get(Type::Int64Ty, 0xFF0000000000ULL),
172                             "bswap.and6", IP);
173    Tmp5 = BinaryOperator::createAnd(Tmp5,
174                             ConstantInt::get(Type::Int64Ty, 0xFF00000000ULL),
175                             "bswap.and5", IP);
176    Tmp4 = BinaryOperator::createAnd(Tmp4,
177                             ConstantInt::get(Type::Int64Ty, 0xFF000000ULL),
178                             "bswap.and4", IP);
179    Tmp3 = BinaryOperator::createAnd(Tmp3,
180                             ConstantInt::get(Type::Int64Ty, 0xFF0000ULL),
181                             "bswap.and3", IP);
182    Tmp2 = BinaryOperator::createAnd(Tmp2,
183                             ConstantInt::get(Type::Int64Ty, 0xFF00ULL),
184                             "bswap.and2", IP);
185    Tmp8 = BinaryOperator::createOr(Tmp8, Tmp7, "bswap.or1", IP);
186    Tmp6 = BinaryOperator::createOr(Tmp6, Tmp5, "bswap.or2", IP);
187    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp3, "bswap.or3", IP);
188    Tmp2 = BinaryOperator::createOr(Tmp2, Tmp1, "bswap.or4", IP);
189    Tmp8 = BinaryOperator::createOr(Tmp8, Tmp6, "bswap.or5", IP);
190    Tmp4 = BinaryOperator::createOr(Tmp4, Tmp2, "bswap.or6", IP);
191    V = BinaryOperator::createOr(Tmp8, Tmp4, "bswap.i64", IP);
192    break;
193  }
194  }
195  return V;
196}
197
198/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
199/// instruction IP.
200static Value *LowerCTPOP(Value *V, Instruction *IP) {
201  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
202
203  static const uint64_t MaskValues[6] = {
204    0x5555555555555555ULL, 0x3333333333333333ULL,
205    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
206    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
207  };
208
209  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
210
211  for (unsigned i = 1, ct = 0; i != BitSize; i <<= 1, ++ct) {
212    Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
213    Value *LHS = BinaryOperator::createAnd(V, MaskCst, "cppop.and1", IP);
214    Value *VShift = new ShiftInst(Instruction::LShr, V,
215                      ConstantInt::get(Type::Int8Ty, i), "ctpop.sh", IP);
216    Value *RHS = BinaryOperator::createAnd(VShift, MaskCst, "cppop.and2", IP);
217    V = BinaryOperator::createAdd(LHS, RHS, "ctpop.step", IP);
218  }
219
220  return V;
221}
222
223/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
224/// instruction IP.
225static Value *LowerCTLZ(Value *V, Instruction *IP) {
226
227  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
228  for (unsigned i = 1; i != BitSize; i <<= 1) {
229    Value *ShVal = ConstantInt::get(Type::Int8Ty, i);
230    ShVal = new ShiftInst(Instruction::LShr, V, ShVal, "ctlz.sh", IP);
231    V = BinaryOperator::createOr(V, ShVal, "ctlz.step", IP);
232  }
233
234  V = BinaryOperator::createNot(V, "", IP);
235  return LowerCTPOP(V, IP);
236}
237
238
239
240void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
241  Function *Callee = CI->getCalledFunction();
242  assert(Callee && "Cannot lower an indirect call!");
243
244  switch (Callee->getIntrinsicID()) {
245  case Intrinsic::not_intrinsic:
246    cerr << "Cannot lower a call to a non-intrinsic function '"
247         << Callee->getName() << "'!\n";
248    abort();
249  default:
250    cerr << "Error: Code generator does not support intrinsic function '"
251         << Callee->getName() << "'!\n";
252    abort();
253
254    // The setjmp/longjmp intrinsics should only exist in the code if it was
255    // never optimized (ie, right out of the CFE), or if it has been hacked on
256    // by the lowerinvoke pass.  In both cases, the right thing to do is to
257    // convert the call to an explicit setjmp or longjmp call.
258  case Intrinsic::setjmp: {
259    static Constant *SetjmpFCache = 0;
260    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin()+1, CI->op_end(),
261                               Type::Int32Ty, SetjmpFCache);
262    if (CI->getType() != Type::VoidTy)
263      CI->replaceAllUsesWith(V);
264    break;
265  }
266  case Intrinsic::sigsetjmp:
267     if (CI->getType() != Type::VoidTy)
268       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
269     break;
270
271  case Intrinsic::longjmp: {
272    static Constant *LongjmpFCache = 0;
273    ReplaceCallWith("longjmp", CI, CI->op_begin()+1, CI->op_end(),
274                    Type::VoidTy, LongjmpFCache);
275    break;
276  }
277
278  case Intrinsic::siglongjmp: {
279    // Insert the call to abort
280    static Constant *AbortFCache = 0;
281    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
282                    Type::VoidTy, AbortFCache);
283    break;
284  }
285  case Intrinsic::ctpop_i8:
286  case Intrinsic::ctpop_i16:
287  case Intrinsic::ctpop_i32:
288  case Intrinsic::ctpop_i64:
289    CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
290    break;
291
292  case Intrinsic::bswap_i16:
293  case Intrinsic::bswap_i32:
294  case Intrinsic::bswap_i64:
295    CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
296    break;
297
298  case Intrinsic::ctlz_i8:
299  case Intrinsic::ctlz_i16:
300  case Intrinsic::ctlz_i32:
301  case Intrinsic::ctlz_i64:
302    CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
303    break;
304
305  case Intrinsic::cttz_i8:
306  case Intrinsic::cttz_i16:
307  case Intrinsic::cttz_i32:
308  case Intrinsic::cttz_i64: {
309    // cttz(x) -> ctpop(~X & (X-1))
310    Value *Src = CI->getOperand(1);
311    Value *NotSrc = BinaryOperator::createNot(Src, Src->getName()+".not", CI);
312    Value *SrcM1  = ConstantInt::get(Src->getType(), 1);
313    SrcM1 = BinaryOperator::createSub(Src, SrcM1, "", CI);
314    Src = LowerCTPOP(BinaryOperator::createAnd(NotSrc, SrcM1, "", CI), CI);
315    CI->replaceAllUsesWith(Src);
316    break;
317  }
318
319  case Intrinsic::stacksave:
320  case Intrinsic::stackrestore: {
321    static bool Warned = false;
322    if (!Warned)
323      cerr << "WARNING: this target does not support the llvm.stack"
324           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
325               "save" : "restore") << " intrinsic.\n";
326    Warned = true;
327    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
328      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
329    break;
330  }
331
332  case Intrinsic::returnaddress:
333  case Intrinsic::frameaddress:
334    cerr << "WARNING: this target does not support the llvm."
335         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
336             "return" : "frame") << "address intrinsic.\n";
337    CI->replaceAllUsesWith(ConstantPointerNull::get(
338                                            cast<PointerType>(CI->getType())));
339    break;
340
341  case Intrinsic::prefetch:
342    break;    // Simply strip out prefetches on unsupported architectures
343
344  case Intrinsic::pcmarker:
345    break;    // Simply strip out pcmarker on unsupported architectures
346  case Intrinsic::readcyclecounter: {
347    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
348         << "ter intrinsic.  It is being lowered to a constant 0\n";
349    CI->replaceAllUsesWith(ConstantInt::get(Type::Int64Ty, 0));
350    break;
351  }
352
353  case Intrinsic::dbg_stoppoint:
354  case Intrinsic::dbg_region_start:
355  case Intrinsic::dbg_region_end:
356  case Intrinsic::dbg_func_start:
357  case Intrinsic::dbg_declare:
358    break;    // Simply strip out debugging intrinsics
359
360  case Intrinsic::memcpy_i32: {
361    static Constant *MemcpyFCache = 0;
362    ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
363                    (*(CI->op_begin()+1))->getType(), MemcpyFCache);
364    break;
365  }
366  case Intrinsic::memcpy_i64: {
367    static Constant *MemcpyFCache = 0;
368    ReplaceCallWith("memcpy", CI, CI->op_begin()+1, CI->op_end()-1,
369                     (*(CI->op_begin()+1))->getType(), MemcpyFCache);
370    break;
371  }
372  case Intrinsic::memmove_i32: {
373    static Constant *MemmoveFCache = 0;
374    ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
375                    (*(CI->op_begin()+1))->getType(), MemmoveFCache);
376    break;
377  }
378  case Intrinsic::memmove_i64: {
379    static Constant *MemmoveFCache = 0;
380    ReplaceCallWith("memmove", CI, CI->op_begin()+1, CI->op_end()-1,
381                    (*(CI->op_begin()+1))->getType(), MemmoveFCache);
382    break;
383  }
384  case Intrinsic::memset_i32: {
385    static Constant *MemsetFCache = 0;
386    ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
387                    (*(CI->op_begin()+1))->getType(), MemsetFCache);
388  }
389  case Intrinsic::memset_i64: {
390    static Constant *MemsetFCache = 0;
391    ReplaceCallWith("memset", CI, CI->op_begin()+1, CI->op_end()-1,
392                    (*(CI->op_begin()+1))->getType(), MemsetFCache);
393    break;
394  }
395  case Intrinsic::isunordered_f32:
396  case Intrinsic::isunordered_f64: {
397    Value *L = CI->getOperand(1);
398    Value *R = CI->getOperand(2);
399
400    Value *LIsNan = new FCmpInst(FCmpInst::FCMP_ONE, L, L, "LIsNan", CI);
401    Value *RIsNan = new FCmpInst(FCmpInst::FCMP_ONE, R, R, "RIsNan", CI);
402    CI->replaceAllUsesWith(
403      BinaryOperator::create(Instruction::Or, LIsNan, RIsNan,
404                             "isunordered", CI));
405    break;
406  }
407  case Intrinsic::sqrt_f32: {
408    static Constant *sqrtfFCache = 0;
409    ReplaceCallWith("sqrtf", CI, CI->op_begin()+1, CI->op_end(),
410                    Type::FloatTy, sqrtfFCache);
411    break;
412  }
413  case Intrinsic::sqrt_f64: {
414    static Constant *sqrtFCache = 0;
415    ReplaceCallWith("sqrt", CI, CI->op_begin()+1, CI->op_end(),
416                    Type::DoubleTy, sqrtFCache);
417    break;
418  }
419  }
420
421  assert(CI->use_empty() &&
422         "Lowering should have eliminated any uses of the intrinsic call!");
423  CI->eraseFromParent();
424}
425