IntrinsicLowering.cpp revision 35b4707edb32008b1a7976dcbf3920b1160fc1c6 
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/IRBuilder.h"
20#include "llvm/Support/ErrorHandling.h"
21#include "llvm/Target/TargetData.h"
22#include "llvm/ADT/SmallVector.h"
23using namespace llvm;
24
25template <class ArgIt>
26static void EnsureFunctionExists(Module &M, const char *Name,
27                                 ArgIt ArgBegin, ArgIt ArgEnd,
28                                 const Type *RetTy) {
29  // Insert a correctly-typed definition now.
30  std::vector<const Type *> ParamTys;
31  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
32    ParamTys.push_back(I->getType());
33  M.getOrInsertFunction(Name, FunctionType::get(RetTy, ParamTys, false));
34}
35
36static void EnsureFPIntrinsicsExist(Module &M, Function *Fn,
37                                    const char *FName,
38                                    const char *DName, const char *LDName) {
39  // Insert definitions for all the floating point types.
40  switch((int)Fn->arg_begin()->getType()->getTypeID()) {
41  case Type::FloatTyID:
42    EnsureFunctionExists(M, FName, Fn->arg_begin(), Fn->arg_end(),
43                         Type::getFloatTy(M.getContext()));
44    break;
45  case Type::DoubleTyID:
46    EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
47                         Type::getDoubleTy(M.getContext()));
48    break;
49  case Type::X86_FP80TyID:
50  case Type::FP128TyID:
51  case Type::PPC_FP128TyID:
52    EnsureFunctionExists(M, LDName, Fn->arg_begin(), Fn->arg_end(),
53                         Fn->arg_begin()->getType());
54    break;
55  }
56}
57
58/// ReplaceCallWith - This function is used when we want to lower an intrinsic
59/// call to a call of an external function.  This handles hard cases such as
60/// when there was already a prototype for the external function, and if that
61/// prototype doesn't match the arguments we expect to pass in.
62template <class ArgIt>
63static CallInst *ReplaceCallWith(const char *NewFn, CallInst *CI,
64                                 ArgIt ArgBegin, ArgIt ArgEnd,
65                                 const Type *RetTy) {
66  // If we haven't already looked up this function, check to see if the
67  // program already contains a function with this name.
68  Module *M = CI->getParent()->getParent()->getParent();
69  // Get or insert the definition now.
70  std::vector<const Type *> ParamTys;
71  for (ArgIt I = ArgBegin; I != ArgEnd; ++I)
72    ParamTys.push_back((*I)->getType());
73  Constant* FCache = M->getOrInsertFunction(NewFn,
74                                  FunctionType::get(RetTy, ParamTys, false));
75
76  IRBuilder<> Builder(CI->getParent(), CI);
77  SmallVector<Value *, 8> Args(ArgBegin, ArgEnd);
78  CallInst *NewCI = Builder.CreateCall(FCache, Args.begin(), Args.end());
79  NewCI->setName(CI->getName());
80  if (!CI->use_empty())
81    CI->replaceAllUsesWith(NewCI);
82  return NewCI;
83}
84
85void IntrinsicLowering::AddPrototypes(Module &M) {
86  LLVMContext &Context = M.getContext();
87  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
88    if (I->isDeclaration() && !I->use_empty())
89      switch (I->getIntrinsicID()) {
90      default: break;
91      case Intrinsic::setjmp:
92        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
93                             Type::getInt32Ty(M.getContext()));
94        break;
95      case Intrinsic::longjmp:
96        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
97                             Type::getVoidTy(M.getContext()));
98        break;
99      case Intrinsic::siglongjmp:
100        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
101                             Type::getVoidTy(M.getContext()));
102        break;
103      case Intrinsic::memcpy:
104        M.getOrInsertFunction("memcpy",
105          PointerType::getUnqual(Type::getInt8Ty(Context)),
106                              PointerType::getUnqual(Type::getInt8Ty(Context)),
107                              PointerType::getUnqual(Type::getInt8Ty(Context)),
108                              TD.getIntPtrType(Context), (Type *)0);
109        break;
110      case Intrinsic::memmove:
111        M.getOrInsertFunction("memmove",
112          PointerType::getUnqual(Type::getInt8Ty(Context)),
113                              PointerType::getUnqual(Type::getInt8Ty(Context)),
114                              PointerType::getUnqual(Type::getInt8Ty(Context)),
115                              TD.getIntPtrType(Context), (Type *)0);
116        break;
117      case Intrinsic::memset:
118        M.getOrInsertFunction("memset",
119          PointerType::getUnqual(Type::getInt8Ty(Context)),
120                              PointerType::getUnqual(Type::getInt8Ty(Context)),
121                              Type::getInt32Ty(M.getContext()),
122                              TD.getIntPtrType(Context), (Type *)0);
123        break;
124      case Intrinsic::sqrt:
125        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
126        break;
127      case Intrinsic::sin:
128        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
129        break;
130      case Intrinsic::cos:
131        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
132        break;
133      case Intrinsic::pow:
134        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
135        break;
136      case Intrinsic::log:
137        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
138        break;
139      case Intrinsic::log2:
140        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
141        break;
142      case Intrinsic::log10:
143        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
144        break;
145      case Intrinsic::exp:
146        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
147        break;
148      case Intrinsic::exp2:
149        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
150        break;
151      }
152}
153
154/// LowerBSWAP - Emit the code to lower bswap of V before the specified
155/// instruction IP.
156static Value *LowerBSWAP(LLVMContext &Context, Value *V, Instruction *IP) {
157  assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
158
159  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
160
161  IRBuilder<> Builder(IP->getParent(), IP);
162
163  switch(BitSize) {
164  default: llvm_unreachable("Unhandled type size of value to byteswap!");
165  case 16: {
166    Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
167                                    "bswap.2");
168    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
169                                     "bswap.1");
170    V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
171    break;
172  }
173  case 32: {
174    Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
175                                    "bswap.4");
176    Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
177                                    "bswap.3");
178    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
179                                     "bswap.2");
180    Value *Tmp1 = Builder.CreateLShr(V,ConstantInt::get(V->getType(), 24),
181                                     "bswap.1");
182    Tmp3 = Builder.CreateAnd(Tmp3,
183                         ConstantInt::get(Type::getInt32Ty(Context), 0xFF0000),
184                             "bswap.and3");
185    Tmp2 = Builder.CreateAnd(Tmp2,
186                           ConstantInt::get(Type::getInt32Ty(Context), 0xFF00),
187                             "bswap.and2");
188    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
189    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
190    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
191    break;
192  }
193  case 64: {
194    Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
195                                    "bswap.8");
196    Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
197                                    "bswap.7");
198    Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
199                                    "bswap.6");
200    Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
201                                    "bswap.5");
202    Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
203                                     "bswap.4");
204    Value* Tmp3 = Builder.CreateLShr(V,
205                                     ConstantInt::get(V->getType(), 24),
206                                     "bswap.3");
207    Value* Tmp2 = Builder.CreateLShr(V,
208                                     ConstantInt::get(V->getType(), 40),
209                                     "bswap.2");
210    Value* Tmp1 = Builder.CreateLShr(V,
211                                     ConstantInt::get(V->getType(), 56),
212                                     "bswap.1");
213    Tmp7 = Builder.CreateAnd(Tmp7,
214                             ConstantInt::get(Type::getInt64Ty(Context),
215                                              0xFF000000000000ULL),
216                             "bswap.and7");
217    Tmp6 = Builder.CreateAnd(Tmp6,
218                             ConstantInt::get(Type::getInt64Ty(Context),
219                                              0xFF0000000000ULL),
220                             "bswap.and6");
221    Tmp5 = Builder.CreateAnd(Tmp5,
222                        ConstantInt::get(Type::getInt64Ty(Context),
223                             0xFF00000000ULL),
224                             "bswap.and5");
225    Tmp4 = Builder.CreateAnd(Tmp4,
226                        ConstantInt::get(Type::getInt64Ty(Context),
227                             0xFF000000ULL),
228                             "bswap.and4");
229    Tmp3 = Builder.CreateAnd(Tmp3,
230                             ConstantInt::get(Type::getInt64Ty(Context),
231                             0xFF0000ULL),
232                             "bswap.and3");
233    Tmp2 = Builder.CreateAnd(Tmp2,
234                             ConstantInt::get(Type::getInt64Ty(Context),
235                             0xFF00ULL),
236                             "bswap.and2");
237    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
238    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
239    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
240    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
241    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
242    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
243    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
244    break;
245  }
246  }
247  return V;
248}
249
250/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
251/// instruction IP.
252static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
253  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
254
255  static const uint64_t MaskValues[6] = {
256    0x5555555555555555ULL, 0x3333333333333333ULL,
257    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
258    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
259  };
260
261  IRBuilder<> Builder(IP->getParent(), IP);
262
263  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
264  unsigned WordSize = (BitSize + 63) / 64;
265  Value *Count = ConstantInt::get(V->getType(), 0);
266
267  for (unsigned n = 0; n < WordSize; ++n) {
268    Value *PartValue = V;
269    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
270         i <<= 1, ++ct) {
271      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
272      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
273      Value *VShift = Builder.CreateLShr(PartValue,
274                                        ConstantInt::get(V->getType(), i),
275                                         "ctpop.sh");
276      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
277      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
278    }
279    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
280    if (BitSize > 64) {
281      V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
282                             "ctpop.part.sh");
283      BitSize -= 64;
284    }
285  }
286
287  return Count;
288}
289
290/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
291/// instruction IP.
292static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
293
294  IRBuilder<> Builder(IP->getParent(), IP);
295
296  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
297  for (unsigned i = 1; i < BitSize; i <<= 1) {
298    Value *ShVal = ConstantInt::get(V->getType(), i);
299    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
300    V = Builder.CreateOr(V, ShVal, "ctlz.step");
301  }
302
303  V = Builder.CreateNot(V);
304  return LowerCTPOP(Context, V, IP);
305}
306
307static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
308                                       const char *Dname,
309                                       const char *LDname) {
310  switch (CI->getOperand(1)->getType()->getTypeID()) {
311  default: llvm_unreachable("Invalid type in intrinsic");
312  case Type::FloatTyID:
313    ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
314                  Type::getFloatTy(CI->getContext()));
315    break;
316  case Type::DoubleTyID:
317    ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
318                  Type::getDoubleTy(CI->getContext()));
319    break;
320  case Type::X86_FP80TyID:
321  case Type::FP128TyID:
322  case Type::PPC_FP128TyID:
323    ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
324                  CI->getOperand(1)->getType());
325    break;
326  }
327}
328
329void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
330  IRBuilder<> Builder(CI->getParent(), CI);
331  LLVMContext &Context = CI->getContext();
332
333  Function *Callee = CI->getCalledFunction();
334  assert(Callee && "Cannot lower an indirect call!");
335
336  switch (Callee->getIntrinsicID()) {
337  case Intrinsic::not_intrinsic:
338    llvm_report_error("Cannot lower a call to a non-intrinsic function '"+
339                      Callee->getName() + "'!");
340  default:
341    llvm_report_error("Code generator does not support intrinsic function '"+
342                      Callee->getName()+"'!");
343
344    // The setjmp/longjmp intrinsics should only exist in the code if it was
345    // never optimized (ie, right out of the CFE), or if it has been hacked on
346    // by the lowerinvoke pass.  In both cases, the right thing to do is to
347    // convert the call to an explicit setjmp or longjmp call.
348  case Intrinsic::setjmp: {
349    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
350                               Type::getInt32Ty(Context));
351    if (CI->getType() != Type::getVoidTy(Context))
352      CI->replaceAllUsesWith(V);
353    break;
354  }
355  case Intrinsic::sigsetjmp:
356     if (CI->getType() != Type::getVoidTy(Context))
357       CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
358     break;
359
360  case Intrinsic::longjmp: {
361    ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
362                    Type::getVoidTy(Context));
363    break;
364  }
365
366  case Intrinsic::siglongjmp: {
367    // Insert the call to abort
368    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
369                    Type::getVoidTy(Context));
370    break;
371  }
372  case Intrinsic::ctpop:
373    CI->replaceAllUsesWith(LowerCTPOP(Context, CI->getOperand(1), CI));
374    break;
375
376  case Intrinsic::bswap:
377    CI->replaceAllUsesWith(LowerBSWAP(Context, CI->getOperand(1), CI));
378    break;
379
380  case Intrinsic::ctlz:
381    CI->replaceAllUsesWith(LowerCTLZ(Context, CI->getOperand(1), CI));
382    break;
383
384  case Intrinsic::cttz: {
385    // cttz(x) -> ctpop(~X & (X-1))
386    Value *Src = CI->getOperand(1);
387    Value *NotSrc = Builder.CreateNot(Src);
388    NotSrc->setName(Src->getName() + ".not");
389    Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
390    SrcM1 = Builder.CreateSub(Src, SrcM1);
391    Src = LowerCTPOP(Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
392    CI->replaceAllUsesWith(Src);
393    break;
394  }
395
396  case Intrinsic::stacksave:
397  case Intrinsic::stackrestore: {
398    if (!Warned)
399      cerr << "WARNING: this target does not support the llvm.stack"
400           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
401               "save" : "restore") << " intrinsic.\n";
402    Warned = true;
403    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
404      CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
405    break;
406  }
407
408  case Intrinsic::returnaddress:
409  case Intrinsic::frameaddress:
410    cerr << "WARNING: this target does not support the llvm."
411         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
412             "return" : "frame") << "address intrinsic.\n";
413    CI->replaceAllUsesWith(ConstantPointerNull::get(
414                                            cast<PointerType>(CI->getType())));
415    break;
416
417  case Intrinsic::prefetch:
418    break;    // Simply strip out prefetches on unsupported architectures
419
420  case Intrinsic::pcmarker:
421    break;    // Simply strip out pcmarker on unsupported architectures
422  case Intrinsic::readcyclecounter: {
423    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
424         << "ter intrinsic.  It is being lowered to a constant 0\n";
425    CI->replaceAllUsesWith(ConstantInt::get(Type::getInt64Ty(Context), 0));
426    break;
427  }
428
429  case Intrinsic::dbg_stoppoint:
430  case Intrinsic::dbg_region_start:
431  case Intrinsic::dbg_region_end:
432  case Intrinsic::dbg_func_start:
433  case Intrinsic::dbg_declare:
434    break;    // Simply strip out debugging intrinsics
435
436  case Intrinsic::eh_exception:
437  case Intrinsic::eh_selector_i32:
438  case Intrinsic::eh_selector_i64:
439    CI->replaceAllUsesWith(Constant::getNullValue(CI->getType()));
440    break;
441
442  case Intrinsic::eh_typeid_for_i32:
443  case Intrinsic::eh_typeid_for_i64:
444    // Return something different to eh_selector.
445    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
446    break;
447
448  case Intrinsic::var_annotation:
449    break;   // Strip out annotate intrinsic
450
451  case Intrinsic::memcpy: {
452    const IntegerType *IntPtr = TD.getIntPtrType(Context);
453    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
454                                        /* isSigned */ false);
455    Value *Ops[3];
456    Ops[0] = CI->getOperand(1);
457    Ops[1] = CI->getOperand(2);
458    Ops[2] = Size;
459    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType());
460    break;
461  }
462  case Intrinsic::memmove: {
463    const IntegerType *IntPtr = TD.getIntPtrType(Context);
464    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
465                                        /* isSigned */ false);
466    Value *Ops[3];
467    Ops[0] = CI->getOperand(1);
468    Ops[1] = CI->getOperand(2);
469    Ops[2] = Size;
470    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType());
471    break;
472  }
473  case Intrinsic::memset: {
474    const IntegerType *IntPtr = TD.getIntPtrType(Context);
475    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
476                                        /* isSigned */ false);
477    Value *Ops[3];
478    Ops[0] = CI->getOperand(1);
479    // Extend the amount to i32.
480    Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::getInt32Ty(Context),
481                                   /* isSigned */ false);
482    Ops[2] = Size;
483    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType());
484    break;
485  }
486  case Intrinsic::sqrt: {
487    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
488    break;
489  }
490  case Intrinsic::log: {
491    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
492    break;
493  }
494  case Intrinsic::log2: {
495    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
496    break;
497  }
498  case Intrinsic::log10: {
499    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
500    break;
501  }
502  case Intrinsic::exp: {
503    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
504    break;
505  }
506  case Intrinsic::exp2: {
507    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
508    break;
509  }
510  case Intrinsic::pow: {
511    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
512    break;
513  }
514  case Intrinsic::flt_rounds:
515     // Lower to "round to the nearest"
516     if (CI->getType() != Type::getVoidTy(Context))
517       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
518     break;
519  }
520
521  assert(CI->use_empty() &&
522         "Lowering should have eliminated any uses of the intrinsic call!");
523  CI->eraseFromParent();
524}
525