IntrinsicLowering.cpp revision 9f5b2aa7fba203469386acc413c23dd41a713bc9 
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(LLVMContext &Context, 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, Context.getConstantInt(V->getType(), 8),
163                                    "bswap.2");
164    Value *Tmp2 = Builder.CreateLShr(V, Context.getConstantInt(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, Context.getConstantInt(V->getType(), 24),
171                                    "bswap.4");
172    Value *Tmp3 = Builder.CreateShl(V, Context.getConstantInt(V->getType(), 8),
173                                    "bswap.3");
174    Value *Tmp2 = Builder.CreateLShr(V, Context.getConstantInt(V->getType(), 8),
175                                     "bswap.2");
176    Value *Tmp1 = Builder.CreateLShr(V,Context.getConstantInt(V->getType(), 24),
177                                     "bswap.1");
178    Tmp3 = Builder.CreateAnd(Tmp3,
179                             Context.getConstantInt(Type::Int32Ty, 0xFF0000),
180                             "bswap.and3");
181    Tmp2 = Builder.CreateAnd(Tmp2,
182                             Context.getConstantInt(Type::Int32Ty, 0xFF00),
183                             "bswap.and2");
184    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or1");
185    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or2");
186    V = Builder.CreateOr(Tmp4, Tmp2, "bswap.i32");
187    break;
188  }
189  case 64: {
190    Value *Tmp8 = Builder.CreateShl(V, Context.getConstantInt(V->getType(), 56),
191                                    "bswap.8");
192    Value *Tmp7 = Builder.CreateShl(V, Context.getConstantInt(V->getType(), 40),
193                                    "bswap.7");
194    Value *Tmp6 = Builder.CreateShl(V, Context.getConstantInt(V->getType(), 24),
195                                    "bswap.6");
196    Value *Tmp5 = Builder.CreateShl(V, Context.getConstantInt(V->getType(), 8),
197                                    "bswap.5");
198    Value* Tmp4 = Builder.CreateLShr(V, Context.getConstantInt(V->getType(), 8),
199                                     "bswap.4");
200    Value* Tmp3 = Builder.CreateLShr(V,
201                                     Context.getConstantInt(V->getType(), 24),
202                                     "bswap.3");
203    Value* Tmp2 = Builder.CreateLShr(V,
204                                     Context.getConstantInt(V->getType(), 40),
205                                     "bswap.2");
206    Value* Tmp1 = Builder.CreateLShr(V,
207                                     Context.getConstantInt(V->getType(), 56),
208                                     "bswap.1");
209    Tmp7 = Builder.CreateAnd(Tmp7,
210                             Context.getConstantInt(Type::Int64Ty,
211                                              0xFF000000000000ULL),
212                             "bswap.and7");
213    Tmp6 = Builder.CreateAnd(Tmp6,
214                             Context.getConstantInt(Type::Int64Ty,
215                                              0xFF0000000000ULL),
216                             "bswap.and6");
217    Tmp5 = Builder.CreateAnd(Tmp5,
218                        Context.getConstantInt(Type::Int64Ty, 0xFF00000000ULL),
219                             "bswap.and5");
220    Tmp4 = Builder.CreateAnd(Tmp4,
221                        Context.getConstantInt(Type::Int64Ty, 0xFF000000ULL),
222                             "bswap.and4");
223    Tmp3 = Builder.CreateAnd(Tmp3,
224                             Context.getConstantInt(Type::Int64Ty, 0xFF0000ULL),
225                             "bswap.and3");
226    Tmp2 = Builder.CreateAnd(Tmp2,
227                             Context.getConstantInt(Type::Int64Ty, 0xFF00ULL),
228                             "bswap.and2");
229    Tmp8 = Builder.CreateOr(Tmp8, Tmp7, "bswap.or1");
230    Tmp6 = Builder.CreateOr(Tmp6, Tmp5, "bswap.or2");
231    Tmp4 = Builder.CreateOr(Tmp4, Tmp3, "bswap.or3");
232    Tmp2 = Builder.CreateOr(Tmp2, Tmp1, "bswap.or4");
233    Tmp8 = Builder.CreateOr(Tmp8, Tmp6, "bswap.or5");
234    Tmp4 = Builder.CreateOr(Tmp4, Tmp2, "bswap.or6");
235    V = Builder.CreateOr(Tmp8, Tmp4, "bswap.i64");
236    break;
237  }
238  }
239  return V;
240}
241
242/// LowerCTPOP - Emit the code to lower ctpop of V before the specified
243/// instruction IP.
244static Value *LowerCTPOP(LLVMContext &Context, Value *V, Instruction *IP) {
245  assert(V->getType()->isInteger() && "Can't ctpop a non-integer type!");
246
247  static const uint64_t MaskValues[6] = {
248    0x5555555555555555ULL, 0x3333333333333333ULL,
249    0x0F0F0F0F0F0F0F0FULL, 0x00FF00FF00FF00FFULL,
250    0x0000FFFF0000FFFFULL, 0x00000000FFFFFFFFULL
251  };
252
253  IRBuilder<> Builder(IP->getParent(), IP);
254
255  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
256  unsigned WordSize = (BitSize + 63) / 64;
257  Value *Count = Context.getConstantInt(V->getType(), 0);
258
259  for (unsigned n = 0; n < WordSize; ++n) {
260    Value *PartValue = V;
261    for (unsigned i = 1, ct = 0; i < (BitSize>64 ? 64 : BitSize);
262         i <<= 1, ++ct) {
263      Value *MaskCst = Context.getConstantInt(V->getType(), MaskValues[ct]);
264      Value *LHS = Builder.CreateAnd(PartValue, MaskCst, "cppop.and1");
265      Value *VShift = Builder.CreateLShr(PartValue,
266                                        Context.getConstantInt(V->getType(), i),
267                                         "ctpop.sh");
268      Value *RHS = Builder.CreateAnd(VShift, MaskCst, "cppop.and2");
269      PartValue = Builder.CreateAdd(LHS, RHS, "ctpop.step");
270    }
271    Count = Builder.CreateAdd(PartValue, Count, "ctpop.part");
272    if (BitSize > 64) {
273      V = Builder.CreateLShr(V, Context.getConstantInt(V->getType(), 64),
274                             "ctpop.part.sh");
275      BitSize -= 64;
276    }
277  }
278
279  return Count;
280}
281
282/// LowerCTLZ - Emit the code to lower ctlz of V before the specified
283/// instruction IP.
284static Value *LowerCTLZ(LLVMContext &Context, Value *V, Instruction *IP) {
285
286  IRBuilder<> Builder(IP->getParent(), IP);
287
288  unsigned BitSize = V->getType()->getPrimitiveSizeInBits();
289  for (unsigned i = 1; i < BitSize; i <<= 1) {
290    Value *ShVal = Context.getConstantInt(V->getType(), i);
291    ShVal = Builder.CreateLShr(V, ShVal, "ctlz.sh");
292    V = Builder.CreateOr(V, ShVal, "ctlz.step");
293  }
294
295  V = Builder.CreateNot(V);
296  return LowerCTPOP(Context, V, IP);
297}
298
299static void ReplaceFPIntrinsicWithCall(CallInst *CI, const char *Fname,
300                                       const char *Dname,
301                                       const char *LDname) {
302  switch (CI->getOperand(1)->getType()->getTypeID()) {
303  default: llvm_unreachable("Invalid type in intrinsic");
304  case Type::FloatTyID:
305    ReplaceCallWith(Fname, CI, CI->op_begin() + 1, CI->op_end(),
306                  Type::FloatTy);
307    break;
308  case Type::DoubleTyID:
309    ReplaceCallWith(Dname, CI, CI->op_begin() + 1, CI->op_end(),
310                  Type::DoubleTy);
311    break;
312  case Type::X86_FP80TyID:
313  case Type::FP128TyID:
314  case Type::PPC_FP128TyID:
315    ReplaceCallWith(LDname, CI, CI->op_begin() + 1, CI->op_end(),
316                  CI->getOperand(1)->getType());
317    break;
318  }
319}
320
321void IntrinsicLowering::LowerIntrinsicCall(CallInst *CI) {
322  IRBuilder<> Builder(CI->getParent(), CI);
323  LLVMContext *Context = CI->getParent()->getContext();
324
325  Function *Callee = CI->getCalledFunction();
326  assert(Callee && "Cannot lower an indirect call!");
327
328  switch (Callee->getIntrinsicID()) {
329  case Intrinsic::not_intrinsic:
330    llvm_report_error("Cannot lower a call to a non-intrinsic function '"+
331                      Callee->getName() + "'!");
332  default:
333    llvm_report_error("Code generator does not support intrinsic function '"+
334                      Callee->getName()+"'!");
335
336    // The setjmp/longjmp intrinsics should only exist in the code if it was
337    // never optimized (ie, right out of the CFE), or if it has been hacked on
338    // by the lowerinvoke pass.  In both cases, the right thing to do is to
339    // convert the call to an explicit setjmp or longjmp call.
340  case Intrinsic::setjmp: {
341    Value *V = ReplaceCallWith("setjmp", CI, CI->op_begin() + 1, CI->op_end(),
342                               Type::Int32Ty);
343    if (CI->getType() != Type::VoidTy)
344      CI->replaceAllUsesWith(V);
345    break;
346  }
347  case Intrinsic::sigsetjmp:
348     if (CI->getType() != Type::VoidTy)
349       CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
350     break;
351
352  case Intrinsic::longjmp: {
353    ReplaceCallWith("longjmp", CI, CI->op_begin() + 1, CI->op_end(),
354                    Type::VoidTy);
355    break;
356  }
357
358  case Intrinsic::siglongjmp: {
359    // Insert the call to abort
360    ReplaceCallWith("abort", CI, CI->op_end(), CI->op_end(),
361                    Type::VoidTy);
362    break;
363  }
364  case Intrinsic::ctpop:
365    CI->replaceAllUsesWith(LowerCTPOP(*Context, CI->getOperand(1), CI));
366    break;
367
368  case Intrinsic::bswap:
369    CI->replaceAllUsesWith(LowerBSWAP(*Context, CI->getOperand(1), CI));
370    break;
371
372  case Intrinsic::ctlz:
373    CI->replaceAllUsesWith(LowerCTLZ(*Context, CI->getOperand(1), CI));
374    break;
375
376  case Intrinsic::cttz: {
377    // cttz(x) -> ctpop(~X & (X-1))
378    Value *Src = CI->getOperand(1);
379    Value *NotSrc = Builder.CreateNot(Src);
380    NotSrc->setName(Src->getName() + ".not");
381    Value *SrcM1 = Context->getConstantInt(Src->getType(), 1);
382    SrcM1 = Builder.CreateSub(Src, SrcM1);
383    Src = LowerCTPOP(*Context, Builder.CreateAnd(NotSrc, SrcM1), CI);
384    CI->replaceAllUsesWith(Src);
385    break;
386  }
387
388  case Intrinsic::stacksave:
389  case Intrinsic::stackrestore: {
390    if (!Warned)
391      cerr << "WARNING: this target does not support the llvm.stack"
392           << (Callee->getIntrinsicID() == Intrinsic::stacksave ?
393               "save" : "restore") << " intrinsic.\n";
394    Warned = true;
395    if (Callee->getIntrinsicID() == Intrinsic::stacksave)
396      CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
397    break;
398  }
399
400  case Intrinsic::returnaddress:
401  case Intrinsic::frameaddress:
402    cerr << "WARNING: this target does not support the llvm."
403         << (Callee->getIntrinsicID() == Intrinsic::returnaddress ?
404             "return" : "frame") << "address intrinsic.\n";
405    CI->replaceAllUsesWith(ConstantPointerNull::get(
406                                            cast<PointerType>(CI->getType())));
407    break;
408
409  case Intrinsic::prefetch:
410    break;    // Simply strip out prefetches on unsupported architectures
411
412  case Intrinsic::pcmarker:
413    break;    // Simply strip out pcmarker on unsupported architectures
414  case Intrinsic::readcyclecounter: {
415    cerr << "WARNING: this target does not support the llvm.readcyclecoun"
416         << "ter intrinsic.  It is being lowered to a constant 0\n";
417    CI->replaceAllUsesWith(Context->getConstantInt(Type::Int64Ty, 0));
418    break;
419  }
420
421  case Intrinsic::dbg_stoppoint:
422  case Intrinsic::dbg_region_start:
423  case Intrinsic::dbg_region_end:
424  case Intrinsic::dbg_func_start:
425  case Intrinsic::dbg_declare:
426    break;    // Simply strip out debugging intrinsics
427
428  case Intrinsic::eh_exception:
429  case Intrinsic::eh_selector_i32:
430  case Intrinsic::eh_selector_i64:
431    CI->replaceAllUsesWith(Context->getNullValue(CI->getType()));
432    break;
433
434  case Intrinsic::eh_typeid_for_i32:
435  case Intrinsic::eh_typeid_for_i64:
436    // Return something different to eh_selector.
437    CI->replaceAllUsesWith(Context->getConstantInt(CI->getType(), 1));
438    break;
439
440  case Intrinsic::var_annotation:
441    break;   // Strip out annotate intrinsic
442
443  case Intrinsic::memcpy: {
444    const IntegerType *IntPtr = TD.getIntPtrType();
445    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
446                                        /* isSigned */ false);
447    Value *Ops[3];
448    Ops[0] = CI->getOperand(1);
449    Ops[1] = CI->getOperand(2);
450    Ops[2] = Size;
451    ReplaceCallWith("memcpy", CI, Ops, Ops+3, CI->getOperand(1)->getType());
452    break;
453  }
454  case Intrinsic::memmove: {
455    const IntegerType *IntPtr = TD.getIntPtrType();
456    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
457                                        /* isSigned */ false);
458    Value *Ops[3];
459    Ops[0] = CI->getOperand(1);
460    Ops[1] = CI->getOperand(2);
461    Ops[2] = Size;
462    ReplaceCallWith("memmove", CI, Ops, Ops+3, CI->getOperand(1)->getType());
463    break;
464  }
465  case Intrinsic::memset: {
466    const IntegerType *IntPtr = TD.getIntPtrType();
467    Value *Size = Builder.CreateIntCast(CI->getOperand(3), IntPtr,
468                                        /* isSigned */ false);
469    Value *Ops[3];
470    Ops[0] = CI->getOperand(1);
471    // Extend the amount to i32.
472    Ops[1] = Builder.CreateIntCast(CI->getOperand(2), Type::Int32Ty,
473                                   /* isSigned */ false);
474    Ops[2] = Size;
475    ReplaceCallWith("memset", CI, Ops, Ops+3, CI->getOperand(1)->getType());
476    break;
477  }
478  case Intrinsic::sqrt: {
479    ReplaceFPIntrinsicWithCall(CI, "sqrtf", "sqrt", "sqrtl");
480    break;
481  }
482  case Intrinsic::log: {
483    ReplaceFPIntrinsicWithCall(CI, "logf", "log", "logl");
484    break;
485  }
486  case Intrinsic::log2: {
487    ReplaceFPIntrinsicWithCall(CI, "log2f", "log2", "log2l");
488    break;
489  }
490  case Intrinsic::log10: {
491    ReplaceFPIntrinsicWithCall(CI, "log10f", "log10", "log10l");
492    break;
493  }
494  case Intrinsic::exp: {
495    ReplaceFPIntrinsicWithCall(CI, "expf", "exp", "expl");
496    break;
497  }
498  case Intrinsic::exp2: {
499    ReplaceFPIntrinsicWithCall(CI, "exp2f", "exp2", "exp2l");
500    break;
501  }
502  case Intrinsic::pow: {
503    ReplaceFPIntrinsicWithCall(CI, "powf", "pow", "powl");
504    break;
505  }
506  case Intrinsic::flt_rounds:
507     // Lower to "round to the nearest"
508     if (CI->getType() != Type::VoidTy)
509       CI->replaceAllUsesWith(Context->getConstantInt(CI->getType(), 1));
510     break;
511  }
512
513  assert(CI->use_empty() &&
514         "Lowering should have eliminated any uses of the intrinsic call!");
515  CI->eraseFromParent();
516}
517