IntrinsicLowering.cpp revision 4ec2258ffb495d7ce00177e447740ef1123a27db 
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/Constants.h"
15#include "llvm/DerivedTypes.h"
16#include "llvm/Module.h"
17#include "llvm/Type.h"
18#include "llvm/CodeGen/IntrinsicLowering.h"
19#include "llvm/Support/ErrorHandling.h"
20#include "llvm/Support/IRBuilder.h"
21#include "llvm/Support/raw_ostream.h"
22#include "llvm/Target/TargetData.h"
23#include "llvm/ADT/SmallVector.h"
24using namespace llvm;
25
26template <class ArgIt>
27static void EnsureFunctionExists(Module &M, const char *Name,
28                                 ArgIt ArgBegin, ArgIt ArgEnd,
29                                 const Type *RetTy) {
30  // Insert a correctly-typed definition now.
31  std::vector<const 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
37static 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/// ReplaceCallWith - This function is used when we want to lower an intrinsic
60/// call to a call of an external function.  This handles hard cases such as
61/// when there was already a prototype for the external function, and if that
62/// prototype doesn't match the arguments we expect to pass in.
63template <class ArgIt>
64static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
65                                 ArgIt ArgBegin, ArgIt ArgEnd,
66                                 const 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->getParent()->getParent()->getParent();
70  // Get or insert the definition now.
71  std::vector<const 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);
78  SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
79  CallInst *NewCI = Builder.CreateCall(FCache, Args.begin(), Args.end());
80  NewCI->setName(CI->getName());
81  if (!CI->use_empty())
82    CI->replaceAllUsesWith(NewCI);
83  return NewCI;
84}
85
86void IntrinsicLowering::AddPrototypes(Module &M) {
87  LLVMContext &Context = M.getContext();
88  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
89    if (I->isDeclaration() && !I->use_empty())
90      switch (I->getIntrinsicID()) {
91      default: break;
92      case Intrinsic::setjmp:
93        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
94                             Type::getInt32Ty(M.getContext()));
95        break;
96      case Intrinsic::longjmp:
97        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
98                             Type::getVoidTy(M.getContext()));
99        break;
100      case Intrinsic::siglongjmp:
101        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
102                             Type::getVoidTy(M.getContext()));
103        break;
104      case Intrinsic::memcpy:
105        M.getOrInsertFunction("memcpy",
106          Type::getInt8PtrTy(Context),
107                              Type::getInt8PtrTy(Context),
108                              Type::getInt8PtrTy(Context),
109                              TD.getIntPtrType(Context), (Type *)0);
110        break;
111      case Intrinsic::memmove:
112        M.getOrInsertFunction("memmove",
113          Type::getInt8PtrTy(Context),
114                              Type::getInt8PtrTy(Context),
115                              Type::getInt8PtrTy(Context),
116                              TD.getIntPtrType(Context), (Type *)0);
117        break;
118      case Intrinsic::memset:
119        M.getOrInsertFunction("memset",
120          Type::getInt8PtrTy(Context),
121                              Type::getInt8PtrTy(Context),
122                              Type::getInt32Ty(M.getContext()),
123                              TD.getIntPtrType(Context), (Type *)0);
124        break;
125      case Intrinsic::sqrt:
126        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
127        break;
128      case Intrinsic::sin:
129        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
130        break;
131      case Intrinsic::cos:
132        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
133        break;
134      case Intrinsic::pow:
135        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
136        break;
137      case Intrinsic::log:
138        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
139        break;
140      case Intrinsic::log2:
141        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
142        break;
143      case Intrinsic::log10:
144        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
145        break;
146      case Intrinsic::exp:
147        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
148        break;
149      case Intrinsic::exp2:
150        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
151        break;
152      }
153}
154
155/// LowerBSWAP - Emit the code to lower bswap of V before the specified
156/// instruction IP.
157static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
158  assert(V->getType()->isIntegerTy() && "Can't bswap a non-integer type!");
159
160  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
161
162  IRBuilder<> Builder(IP->getParent(), IP);
163
164  switch(BitSize) {
165  default: llvm_unreachable("Unhandled type size of value to byteswap!");
166  case 16: {
167    Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
168                                    "bswap.2");
169    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
170                                     "bswap.1");
171    V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
172    break;
173  }
174  case 32: {
175    Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
176                                    "bswap.4");
177    Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
178                                    "bswap.3");
179    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
180                                     "bswap.2");
181    Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
182                                     "bswap.1");
183    Tmp3 = Builder.CreateAnd(Tmp3,
184                         ConstantInt::get(Type::getInt32Ty(Context), 0xFF0000),
185                             "bswap.and3");
186    Tmp2 = Builder.CreateAnd(Tmp2,
187                           ConstantInt::get(Type::getInt32Ty(Context), 0xFF00),
188                             "bswap.and2");
189    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
190    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
191    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
192    break;
193  }
194  case 64: {
195    Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
196                                    "bswap.8");
197    Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
198                                    "bswap.7");
199    Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
200                                    "bswap.6");
201    Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
202                                    "bswap.5");
203    Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
204                                     "bswap.4");
205    Value* Tmp3 = Builder.CreateLShr(V,
206                                     ConstantInt::get(V->getType(), 24),
207                                     "bswap.3");
208    Value* Tmp2 = Builder.CreateLShr(V,
209                                     ConstantInt::get(V->getType(), 40),
210                                     "bswap.2");
211    Value* Tmp1 = Builder.CreateLShr(V,
212                                     ConstantInt::get(V->getType(), 56),
213                                     "bswap.1");
214    Tmp7 = Builder.CreateAnd(Tmp7,
215                             ConstantInt::get(Type::getInt64Ty(Context),
216                                              0xFF000000000000ULL),
217                             "bswap.and7");
218    Tmp6 = Builder.CreateAnd(Tmp6,
219                             ConstantInt::get(Type::getInt64Ty(Context),
220                                              0xFF0000000000ULL),
221                             "bswap.and6");
222    Tmp5 = Builder.CreateAnd(Tmp5,
223                        ConstantInt::get(Type::getInt64Ty(Context),
224                             0xFF00000000ULL),
225                             "bswap.and5");
226    Tmp4 = Builder.CreateAnd(Tmp4,
227                        ConstantInt::get(Type::getInt64Ty(Context),
228                             0xFF000000ULL),
229                             "bswap.and4");
230    Tmp3 = Builder.CreateAnd(Tmp3,
231                             ConstantInt::get(Type::getInt64Ty(Context),
232                             0xFF0000ULL),
233                             "bswap.and3");
234    Tmp2 = Builder.CreateAnd(Tmp2,
235                             ConstantInt::get(Type::getInt64Ty(Context),
236                             0xFF00ULL),
237                             "bswap.and2");
238    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
239    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
240    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
241    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
242    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
243    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
244    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
245    break;
246  }
247  }
248  return V;
249}
250
251/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
252/// instruction IP.
253static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
254  assert(V->getType()->isIntegerTy() && "Can't ctpop a non-integer type!");
255
256  static const uint64_t MaskValues[6] = {
257    0x5555555555555555ULL, 0x3333333333333333ULL,
258    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
259    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
260  };
261
262  IRBuilder<> Builder(IP->getParent(), IP);
263
264  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
265  unsigned WordSize = (BitSize + 63) / 64;
266  Value *Count = ConstantInt::get(V->getType(), 0);
267
268  for (unsigned n = 0; n < WordSize; ++n) {
269    Value *PartValue = V;
270    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
271         i <<= 1, ++ct) {
272      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
273      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
274      Value *VShift = Builder.CreateLShr(PartValue,
275                                        ConstantInt::get(V->getType(), i),
276                                         "ctpop.sh");
277      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
278      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
279    }
280    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
281    if (BitSize > 64) {
282      V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
283                             "ctpop.part.sh");
284      BitSize -= 64;
285    }
286  }
287
288  return Count;
289}
290
291/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
292/// instruction IP.
293static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
294
295  IRBuilder<> Builder(IP->getParent(), IP);
296
297  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
298  for (unsigned i = 1; i < BitSize; i <<= 1) {
299    Value *ShVal = ConstantInt::get(V->getType(), i);
300    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
301    V = Builder.CreateOr(V, ShVal, "ctlz.step");
302  }
303
304  V = Builder.CreateNot(V);
305  return LowerCTPOP(Context, V, IP);
306}
307
308static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
309                                       const char *Dname,
310                                       const char *LDname) {
311  switch (CI->getOperand(0)->getType()->getTypeID()) {
312  default: llvm_unreachable("Invalid type in intrinsic");
313  case Type::FloatTyID:
314    ReplaceCallWith(Fname, CI, CI->op_begin(), CI->op_end() - 1,
315                  Type::getFloatTy(CI->getContext()));
316    break;
317  case Type::DoubleTyID:
318    ReplaceCallWith(Dname, CI, CI->op_begin(), CI->op_end() - 1,
319                  Type::getDoubleTy(CI->getContext()));
320    break;
321  case Type::X86_FP80TyID:
322  case Type::FP128TyID:
323  case Type::PPC_FP128TyID:
324    ReplaceCallWith(LDname, CI, CI->op_begin(), CI->op_end() - 1,
325                  CI->getOperand(0)->getType());
326    break;
327  }
328}
329
330void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
331  IRBuilder<> Builder(CI->getParent(), CI);
332  LLVMContext &Context = CI->getContext();
333
334  const Function *Callee = CI->getCalledFunction();
335  assert(Callee && "Cannot lower an indirect call!");
336
337  switch (Callee->getIntrinsicID()) {
338  case Intrinsic::not_intrinsic:
339    report_fatal_error("Cannot lower a call to a non-intrinsic function '"+
340                      Callee->getName() + "'!");
341  default:
342    report_fatal_error("Code generator does not support intrinsic function '"+
343                      Callee->getName()+"'!");
344
345    // The setjmp/longjmp intrinsics should only exist in the code if it was
346    // never optimized (ie, right out of the CFE), or if it has been hacked on
347    // by the lowerinvoke pass.  In both cases, the right thing to do is to
348    // convert the call to an explicit setjmp or longjmp call.
349  case Intrinsic::setjmp: {
350    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin(), CI->op_end() - 1,
351                               Type::getInt32Ty(Context));
352    if (!CI->getType()->isVoidTy())
353      CI->replaceAllUsesWith(V);
354    break;
355  }
356  case Intrinsic::sigsetjmp:
357     if (!CI->getType()->isVoidTy())
358       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
359     break;
360
361  case Intrinsic::longjmp: {
362    ReplaceCallWith("longjmp", CI, CI->op_begin(), CI->op_end() - 1,
363                    Type::getVoidTy(Context));
364    break;
365  }
366
367  case Intrinsic::siglongjmp: {
368    // Insert the call to abort
369    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
370                    Type::getVoidTy(Context));
371    break;
372  }
373  case Intrinsic::ctpop:
374    CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getOperand(0), CI));
375    break;
376
377  case Intrinsic::bswap:
378    CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getOperand(0), CI));
379    break;
380
381  case Intrinsic::ctlz:
382    CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getOperand(0), CI));
383    break;
384
385  case Intrinsic::cttz: {
386    // cttz(x) -> ctpop(~X & (X-1))
387    Value *Src = CI->getOperand(0);
388    Value *NotSrc = Builder.CreateNot(Src);
389    NotSrc->setName(Src->getName() + ".not");
390    Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
391    SrcM1 = Builder.CreateSub(Src, SrcM1);
392    Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
393    CI->replaceAllUsesWith(Src);
394    break;
395  }
396
397  case Intrinsic::stacksave:
398  case Intrinsic::stackrestore: {
399    if (!Warned)
400      errs() << "WARNING: this target does not support the llvm.stack"
401             << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
402               "save" : "restore") << " intrinsic.\n";
403    Warned = true;
404    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
405      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
406    break;
407  }
408
409  case Intrinsic::returnaddress:
410  case Intrinsic::frameaddress:
411    errs() << "WARNING: this target does not support the llvm."
412           << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
413             "return" : "frame") << "address intrinsic.\n";
414    CI->replaceAllUsesWith(ConstantPointerNull::get(
415                                            cast<PointerType>(CI->getType())));
416    break;
417
418  case Intrinsic::prefetch:
419    break;    // Simply strip out prefetches on unsupported architectures
420
421  case Intrinsic::pcmarker:
422    break;    // Simply strip out pcmarker on unsupported architectures
423  case Intrinsic::readcyclecounter: {
424    errs() << "WARNING: this target does not support the llvm.readcyclecoun"
425           << "ter intrinsic.  It is being lowered to a constant 0\n";
426    CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
427    break;
428  }
429
430  case Intrinsic::dbg_declare:
431    break;    // Simply strip out debugging intrinsics
432
433  case Intrinsic::eh_exception:
434  case Intrinsic::eh_selector:
435    CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
436    break;
437
438  case Intrinsic::eh_typeid_for:
439    // Return something different to eh_selector.
440    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
441    break;
442
443  case Intrinsic::var_annotation:
444    break;   // Strip out annotate intrinsic
445
446  case Intrinsic::memcpy: {
447    const IntegerType *IntPtr = TD.getIntPtrType(Context);
448    Value *Size = Builder.CreateIntCast(CI->getOperand(2), IntPtr,
449                                        /* isSigned */ false);
450    Value *Ops[3];
451    Ops[0] = CI->getOperand(0);
452    Ops[1] = CI->getOperand(1);
453    Ops[2] = Size;
454    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(0)->getType());
455    break;
456  }
457  case Intrinsic::memmove: {
458    const IntegerType *IntPtr = TD.getIntPtrType(Context);
459    Value *Size = Builder.CreateIntCast(CI->getOperand(2), IntPtr,
460                                        /* isSigned */ false);
461    Value *Ops[3];
462    Ops[0] = CI->getOperand(0);
463    Ops[1] = CI->getOperand(1);
464    Ops[2] = Size;
465    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(0)->getType());
466    break;
467  }
468  case Intrinsic::memset: {
469    const IntegerType *IntPtr = TD.getIntPtrType(Context);
470    Value *Size = Builder.CreateIntCast(CI->getOperand(2), IntPtr,
471                                        /* isSigned */ false);
472    Value *Ops[3];
473    Ops[0] = CI->getOperand(0);
474    // Extend the amount to i32.
475    Ops[1] = Builder.CreateIntCast(CI->getOperand(1), Type::getInt32Ty(Context),
476                                   /* isSigned */ false);
477    Ops[2] = Size;
478    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(0)->getType());
479    break;
480  }
481  case Intrinsic::sqrt: {
482    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
483    break;
484  }
485  case Intrinsic::log: {
486    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
487    break;
488  }
489  case Intrinsic::log2: {
490    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
491    break;
492  }
493  case Intrinsic::log10: {
494    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
495    break;
496  }
497  case Intrinsic::exp: {
498    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
499    break;
500  }
501  case Intrinsic::exp2: {
502    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
503    break;
504  }
505  case Intrinsic::pow: {
506    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
507    break;
508  }
509  case Intrinsic::flt_rounds:
510     // Lower to "round to the nearest"
511     if (!CI->getType()->isVoidTy())
512       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
513     break;
514  case Intrinsic::invariant_start:
515  case Intrinsic::lifetime_start:
516    // Discard region information.
517    CI->replaceAllUsesWith(UndefValue::get(CI->getType()));
518    break;
519  case Intrinsic::invariant_end:
520  case Intrinsic::lifetime_end:
521    // Discard region information.
522    break;
523  }
524
525  assert(CI->use_empty() &&
526         "Lowering should have eliminated any uses of the intrinsic call!");
527  CI->eraseFromParent();
528}
529