IntrinsicLowering.cpp revision 0a5372ed3e8cda10d724feda3c1a1c998db05ca0 
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::FloatTy);
44    break;
45  case Type::DoubleTyID:
46    EnsureFunctionExists(M, DName, Fn->arg_begin(), Fn->arg_end(),
47                         Type::DoubleTy);
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  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
87    if (I->isDeclaration() && !I->use_empty())
88      switch (I->getIntrinsicID()) {
89      default: break;
90      case Intrinsic::setjmp:
91        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
92                             Type::Int32Ty);
93        break;
94      case Intrinsic::longjmp:
95        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
96                             Type::VoidTy);
97        break;
98      case Intrinsic::siglongjmp:
99        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
100                             Type::VoidTy);
101        break;
102      case Intrinsic::memcpy:
103        M.getOrInsertFunction("memcpy", PointerType::getUnqual(Type::Int8Ty),
104                              PointerType::getUnqual(Type::Int8Ty),
105                              PointerType::getUnqual(Type::Int8Ty),
106                              TD.getIntPtrType(), (Type *)0);
107        break;
108      case Intrinsic::memmove:
109        M.getOrInsertFunction("memmove", PointerType::getUnqual(Type::Int8Ty),
110                              PointerType::getUnqual(Type::Int8Ty),
111                              PointerType::getUnqual(Type::Int8Ty),
112                              TD.getIntPtrType(), (Type *)0);
113        break;
114      case Intrinsic::memset:
115        M.getOrInsertFunction("memset", PointerType::getUnqual(Type::Int8Ty),
116                              PointerType::getUnqual(Type::Int8Ty),
117                              Type::Int32Ty,
118                              TD.getIntPtrType(), (Type *)0);
119        break;
120      case Intrinsic::sqrt:
121        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
122        break;
123      case Intrinsic::sin:
124        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
125        break;
126      case Intrinsic::cos:
127        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
128        break;
129      case Intrinsic::pow:
130        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
131        break;
132      case Intrinsic::log:
133        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
134        break;
135      case Intrinsic::log2:
136        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
137        break;
138      case Intrinsic::log10:
139        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
140        break;
141      case Intrinsic::exp:
142        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
143        break;
144      case Intrinsic::exp2:
145        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
146        break;
147      }
148}
149
150/// LowerBSWAP - Emit the code to lower bswap of V before the specified
151/// instruction IP.
152static Value *LowerBSWAP(Value *V, Instruction *IP) {
153  assert(V->getType()->isInteger() && "Can't bswap a non-integer type!");
154
155  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
156
157  IRBuilder<> Builder(IP->getParent(), IP);
158
159  switch(BitSize) {
160  default: LLVM_UNREACHABLE("Unhandled type size of value to byteswap!");
161  case 16: {
162    Value *Tmp1 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
163                                    "bswap.2");
164    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
165                                     "bswap.1");
166    V = Builder.CreateOr(Tmp1, Tmp2, "bswap.i16");
167    break;
168  }
169  case 32: {
170    Value *Tmp4 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
171                                    "bswap.4");
172    Value *Tmp3 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
173                                    "bswap.3");
174    Value *Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
175                                     "bswap.2");
176    Value *Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
177                                     "bswap.1");
178    Tmp3 = Builder.CreateAnd(Tmp3, ConstantInt::get(Type::Int32Ty, 0xFF0000),
179                             "bswap.and3");
180    Tmp2 = Builder.CreateAnd(Tmp2, ConstantInt::get(Type::Int32Ty, 0xFF00),
181                             "bswap.and2");
182    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
183    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
184    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
185    break;
186  }
187  case 64: {
188    Value *Tmp8 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 56),
189                                    "bswap.8");
190    Value *Tmp7 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 40),
191                                    "bswap.7");
192    Value *Tmp6 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 24),
193                                    "bswap.6");
194    Value *Tmp5 = Builder.CreateShl(V, ConstantInt::get(V->getType(), 8),
195                                    "bswap.5");
196    Value* Tmp4 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 8),
197                                     "bswap.4");
198    Value* Tmp3 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 24),
199                                     "bswap.3");
200    Value* Tmp2 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 40),
201                                     "bswap.2");
202    Value* Tmp1 = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 56),
203                                     "bswap.1");
204    Tmp7 = Builder.CreateAnd(Tmp7,
205                             ConstantInt::get(Type::Int64Ty,
206                                              0xFF000000000000ULL),
207                             "bswap.and7");
208    Tmp6 = Builder.CreateAnd(Tmp6,
209                             ConstantInt::get(Type::Int64Ty,
210                                              0xFF0000000000ULL),
211                             "bswap.and6");
212    Tmp5 = Builder.CreateAnd(Tmp5,
213                             ConstantInt::get(Type::Int64Ty, 0xFF00000000ULL),
214                             "bswap.and5");
215    Tmp4 = Builder.CreateAnd(Tmp4,
216                             ConstantInt::get(Type::Int64Ty, 0xFF000000ULL),
217                             "bswap.and4");
218    Tmp3 = Builder.CreateAnd(Tmp3,
219                             ConstantInt::get(Type::Int64Ty, 0xFF0000ULL),
220                             "bswap.and3");
221    Tmp2 = Builder.CreateAnd(Tmp2,
222                             ConstantInt::get(Type::Int64Ty, 0xFF00ULL),
223                             "bswap.and2");
224    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
225    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
226    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
227    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
228    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
229    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
230    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
231    break;
232  }
233  }
234  return V;
235}
236
237/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
238/// instruction IP.
239static Value *LowerCTPOP(Value *V, Instruction *IP) {
240  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
241
242  static const uint64_t MaskValues[6] = {
243    0x5555555555555555ULL, 0x3333333333333333ULL,
244    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
245    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
246  };
247
248  IRBuilder<> Builder(IP->getParent(), IP);
249
250  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
251  unsigned WordSize = (BitSize + 63) / 64;
252  Value *Count = ConstantInt::get(V->getType(), 0);
253
254  for (unsigned n = 0; n < WordSize; ++n) {
255    Value *PartValue = V;
256    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
257         i <<= 1, ++ct) {
258      Value *MaskCst = ConstantInt::get(V->getType(), MaskValues[ct]);
259      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
260      Value *VShift = Builder.CreateLShr(PartValue,
261                                         ConstantInt::get(V->getType(), i),
262                                         "ctpop.sh");
263      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
264      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
265    }
266    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
267    if (BitSize > 64) {
268      V = Builder.CreateLShr(V, ConstantInt::get(V->getType(), 64),
269                             "ctpop.part.sh");
270      BitSize -= 64;
271    }
272  }
273
274  return Count;
275}
276
277/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
278/// instruction IP.
279static Value *LowerCTLZ(Value *V, Instruction *IP) {
280
281  IRBuilder<> Builder(IP->getParent(), IP);
282
283  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
284  for (unsigned i = 1; i < BitSize; i <<= 1) {
285    Value *ShVal = ConstantInt::get(V->getType(), i);
286    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
287    V = Builder.CreateOr(V, ShVal, "ctlz.step");
288  }
289
290  V = Builder.CreateNot(V);
291  return LowerCTPOP(V, IP);
292}
293
294static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
295                                       const char *Dname,
296                                       const char *LDname) {
297  switch (CI->getOperand(1)->getType()->getTypeID()) {
298  default: LLVM_UNREACHABLE( "Invalid type in intrinsic");
299  case Type::FloatTyID:
300    ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
301                  Type::FloatTy);
302    break;
303  case Type::DoubleTyID:
304    ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
305                  Type::DoubleTy);
306    break;
307  case Type::X86_FP80TyID:
308  case Type::FP128TyID:
309  case Type::PPC_FP128TyID:
310    ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
311                  CI->getOperand(1)->getType());
312    break;
313  }
314}
315
316void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
317  IRBuilder<> Builder(CI->getParent(), CI);
318  LLVMContext *Context = CI->getParent()->getContext();
319
320  Function *Callee = CI->getCalledFunction();
321  assert(Callee && "Cannot lower an indirect call!");
322
323  switch (Callee->getIntrinsicID()) {
324  case Intrinsic::not_intrinsic:
325    llvm_report_error("Cannot lower a call to a non-intrinsic function '"+
326                      Callee->getName() + "'!");
327  default:
328    llvm_report_error("Code generator does not support intrinsic function '"+
329                      Callee->getName()+"'!");
330
331    // The setjmp/longjmp intrinsics should only exist in the code if it was
332    // never optimized (ie, right out of the CFE), or if it has been hacked on
333    // by the lowerinvoke pass.  In both cases, the right thing to do is to
334    // convert the call to an explicit setjmp or longjmp call.
335  case Intrinsic::setjmp: {
336    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
337                               Type::Int32Ty);
338    if (CI->getType() != Type::VoidTy)
339      CI->replaceAllUsesWith(V);
340    break;
341  }
342  case Intrinsic::sigsetjmp:
343     if (CI->getType() != Type::VoidTy)
344       CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
345     break;
346
347  case Intrinsic::longjmp: {
348    ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
349                    Type::VoidTy);
350    break;
351  }
352
353  case Intrinsic::siglongjmp: {
354    // Insert the call to abort
355    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
356                    Type::VoidTy);
357    break;
358  }
359  case Intrinsic::ctpop:
360    CI->replaceAllUsesWith(LowerCTPOP(CI->getOperand(1), CI));
361    break;
362
363  case Intrinsic::bswap:
364    CI->replaceAllUsesWith(LowerBSWAP(CI->getOperand(1), CI));
365    break;
366
367  case Intrinsic::ctlz:
368    CI->replaceAllUsesWith(LowerCTLZ(CI->getOperand(1), CI));
369    break;
370
371  case Intrinsic::cttz: {
372    // cttz(x) -> ctpop(~X & (X-1))
373    Value *Src = CI->getOperand(1);
374    Value *NotSrc = Builder.CreateNot(Src);
375    NotSrc->setName(Src->getName() + ".not");
376    Value *SrcM1 = ConstantInt::get(Src->getType(), 1);
377    SrcM1 = Builder.CreateSub(Src, SrcM1);
378    Src = LowerCTPOP(Builder.CreateAnd(NotSrc, SrcM1), CI);
379    CI->replaceAllUsesWith(Src);
380    break;
381  }
382
383  case Intrinsic::stacksave:
384  case Intrinsic::stackrestore: {
385    if (!Warned)
386      cerr << "WARNING: this target does not support the llvm.stack"
387           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
388               "save" : "restore") << " intrinsic.\n";
389    Warned = true;
390    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
391      CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
392    break;
393  }
394
395  case Intrinsic::returnaddress:
396  case Intrinsic::frameaddress:
397    cerr << "WARNING: this target does not support the llvm."
398         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
399             "return" : "frame") << "address intrinsic.\n";
400    CI->replaceAllUsesWith(ConstantPointerNull::get(
401                                            cast<PointerType>(CI->getType())));
402    break;
403
404  case Intrinsic::prefetch:
405    break;    // Simply strip out prefetches on unsupported architectures
406
407  case Intrinsic::pcmarker:
408    break;    // Simply strip out pcmarker on unsupported architectures
409  case Intrinsic::readcyclecounter: {
410    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
411         << "ter intrinsic.  It is being lowered to a constant 0\n";
412    CI->replaceAllUsesWith(ConstantInt::get(Type::Int64Ty, 0));
413    break;
414  }
415
416  case Intrinsic::dbg_stoppoint:
417  case Intrinsic::dbg_region_start:
418  case Intrinsic::dbg_region_end:
419  case Intrinsic::dbg_func_start:
420  case Intrinsic::dbg_declare:
421    break;    // Simply strip out debugging intrinsics
422
423  case Intrinsic::eh_exception:
424  case Intrinsic::eh_selector_i32:
425  case Intrinsic::eh_selector_i64:
426    CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
427    break;
428
429  case Intrinsic::eh_typeid_for_i32:
430  case Intrinsic::eh_typeid_for_i64:
431    // Return something different to eh_selector.
432    CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
433    break;
434
435  case Intrinsic::var_annotation:
436    break;   // Strip out annotate intrinsic
437
438  case Intrinsic::memcpy: {
439    const IntegerType *IntPtr = TD.getIntPtrType();
440    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
441                                        /* isSigned */ false);
442    Value *Ops[3];
443    Ops[0] = CI->getOperand(1);
444    Ops[1] = CI->getOperand(2);
445    Ops[2] = Size;
446    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType());
447    break;
448  }
449  case Intrinsic::memmove: {
450    const IntegerType *IntPtr = TD.getIntPtrType();
451    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
452                                        /* isSigned */ false);
453    Value *Ops[3];
454    Ops[0] = CI->getOperand(1);
455    Ops[1] = CI->getOperand(2);
456    Ops[2] = Size;
457    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType());
458    break;
459  }
460  case Intrinsic::memset: {
461    const IntegerType *IntPtr = TD.getIntPtrType();
462    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
463                                        /* isSigned */ false);
464    Value *Ops[3];
465    Ops[0] = CI->getOperand(1);
466    // Extend the amount to i32.
467    Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::Int32Ty,
468                                   /* isSigned */ false);
469    Ops[2] = Size;
470    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType());
471    break;
472  }
473  case Intrinsic::sqrt: {
474    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
475    break;
476  }
477  case Intrinsic::log: {
478    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
479    break;
480  }
481  case Intrinsic::log2: {
482    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
483    break;
484  }
485  case Intrinsic::log10: {
486    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
487    break;
488  }
489  case Intrinsic::exp: {
490    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
491    break;
492  }
493  case Intrinsic::exp2: {
494    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
495    break;
496  }
497  case Intrinsic::pow: {
498    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
499    break;
500  }
501  case Intrinsic::flt_rounds:
502     // Lower to "round to the nearest"
503     if (CI->getType() != Type::VoidTy)
504       CI->replaceAllUsesWith(ConstantInt::get(CI->getType(), 1));
505     break;
506  }
507
508  assert(CI->use_empty() &&
509         "Lowering should have eliminated any uses of the intrinsic call!");
510  CI->eraseFromParent();
511}
512