InstCombineCalls.cpp revision 0976e00fd1cbf4128daeb72efd8957d00383fda9 
1//===- InstCombineCalls.cpp -----------------------------------------------===//
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 visitCall and visitInvoke functions.
11//
12//===----------------------------------------------------------------------===//
13
14#include "InstCombine.h"
15#include "llvm/Support/CallSite.h"
16#include "llvm/DataLayout.h"
17#include "llvm/Analysis/MemoryBuiltins.h"
18#include "llvm/Transforms/Utils/BuildLibCalls.h"
19#include "llvm/Transforms/Utils/Local.h"
20using namespace llvm;
21
22/// getPromotedType - Return the specified type promoted as it would be to pass
23/// though a va_arg area.
24static Type *getPromotedType(Type *Ty) {
25  if (IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
26    if (ITy->getBitWidth() < 32)
27      return Type::getInt32Ty(Ty->getContext());
28  }
29  return Ty;
30}
31
32/// reduceToSingleValueType - Given an aggregate type which ultimately holds a
33/// single scalar element, like {{{type}}} or [1 x type], return type.
34static Type *reduceToSingleValueType(Type *T) {
35  while (!T->isSingleValueType()) {
36    if (StructType *STy = dyn_cast<StructType>(T)) {
37      if (STy->getNumElements() == 1)
38        T = STy->getElementType(0);
39      else
40        break;
41    } else if (ArrayType *ATy = dyn_cast<ArrayType>(T)) {
42      if (ATy->getNumElements() == 1)
43        T = ATy->getElementType();
44      else
45        break;
46    } else
47      break;
48  }
49
50  return T;
51}
52
53Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
54  unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), TD);
55  unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), TD);
56  unsigned MinAlign = std::min(DstAlign, SrcAlign);
57  unsigned CopyAlign = MI->getAlignment();
58
59  if (CopyAlign < MinAlign) {
60    MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
61                                             MinAlign, false));
62    return MI;
63  }
64
65  // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
66  // load/store.
67  ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getArgOperand(2));
68  if (MemOpLength == 0) return 0;
69
70  // Source and destination pointer types are always "i8*" for intrinsic.  See
71  // if the size is something we can handle with a single primitive load/store.
72  // A single load+store correctly handles overlapping memory in the memmove
73  // case.
74  uint64_t Size = MemOpLength->getLimitedValue();
75  assert(Size && "0-sized memory transfering should be removed already.");
76
77  if (Size > 8 || (Size&(Size-1)))
78    return 0;  // If not 1/2/4/8 bytes, exit.
79
80  // Use an integer load+store unless we can find something better.
81  unsigned SrcAddrSp =
82    cast<PointerType>(MI->getArgOperand(1)->getType())->getAddressSpace();
83  unsigned DstAddrSp =
84    cast<PointerType>(MI->getArgOperand(0)->getType())->getAddressSpace();
85
86  IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3);
87  Type *NewSrcPtrTy = PointerType::get(IntType, SrcAddrSp);
88  Type *NewDstPtrTy = PointerType::get(IntType, DstAddrSp);
89
90  // Memcpy forces the use of i8* for the source and destination.  That means
91  // that if you're using memcpy to move one double around, you'll get a cast
92  // from double* to i8*.  We'd much rather use a double load+store rather than
93  // an i64 load+store, here because this improves the odds that the source or
94  // dest address will be promotable.  See if we can find a better type than the
95  // integer datatype.
96  Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts();
97  MDNode *CopyMD = 0;
98  if (StrippedDest != MI->getArgOperand(0)) {
99    Type *SrcETy = cast<PointerType>(StrippedDest->getType())
100                                    ->getElementType();
101    if (TD && SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
102      // The SrcETy might be something like {{{double}}} or [1 x double].  Rip
103      // down through these levels if so.
104      SrcETy = reduceToSingleValueType(SrcETy);
105
106      if (SrcETy->isSingleValueType()) {
107        NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp);
108        NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp);
109
110        // If the memcpy has metadata describing the members, see if we can
111        // get the TBAA tag describing our copy.
112        if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) {
113          if (M->getNumOperands() == 3 &&
114              M->getOperand(0) &&
115              isa<ConstantInt>(M->getOperand(0)) &&
116              cast<ConstantInt>(M->getOperand(0))->isNullValue() &&
117              M->getOperand(1) &&
118              isa<ConstantInt>(M->getOperand(1)) &&
119              cast<ConstantInt>(M->getOperand(1))->getValue() == Size &&
120              M->getOperand(2) &&
121              isa<MDNode>(M->getOperand(2)))
122            CopyMD = cast<MDNode>(M->getOperand(2));
123        }
124      }
125    }
126  }
127
128  // If the memcpy/memmove provides better alignment info than we can
129  // infer, use it.
130  SrcAlign = std::max(SrcAlign, CopyAlign);
131  DstAlign = std::max(DstAlign, CopyAlign);
132
133  Value *Src = Builder->CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy);
134  Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy);
135  LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile());
136  L->setAlignment(SrcAlign);
137  if (CopyMD)
138    L->setMetadata(LLVMContext::MD_tbaa, CopyMD);
139  StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile());
140  S->setAlignment(DstAlign);
141  if (CopyMD)
142    S->setMetadata(LLVMContext::MD_tbaa, CopyMD);
143
144  // Set the size of the copy to 0, it will be deleted on the next iteration.
145  MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType()));
146  return MI;
147}
148
149Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
150  unsigned Alignment = getKnownAlignment(MI->getDest(), TD);
151  if (MI->getAlignment() < Alignment) {
152    MI->setAlignment(ConstantInt::get(MI->getAlignmentType(),
153                                             Alignment, false));
154    return MI;
155  }
156
157  // Extract the length and alignment and fill if they are constant.
158  ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
159  ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
160  if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8))
161    return 0;
162  uint64_t Len = LenC->getLimitedValue();
163  Alignment = MI->getAlignment();
164  assert(Len && "0-sized memory setting should be removed already.");
165
166  // memset(s,c,n) -> store s, c (for n=1,2,4,8)
167  if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
168    Type *ITy = IntegerType::get(MI->getContext(), Len*8);  // n=1 -> i8.
169
170    Value *Dest = MI->getDest();
171    unsigned DstAddrSp = cast<PointerType>(Dest->getType())->getAddressSpace();
172    Type *NewDstPtrTy = PointerType::get(ITy, DstAddrSp);
173    Dest = Builder->CreateBitCast(Dest, NewDstPtrTy);
174
175    // Alignment 0 is identity for alignment 1 for memset, but not store.
176    if (Alignment == 0) Alignment = 1;
177
178    // Extract the fill value and store.
179    uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
180    StoreInst *S = Builder->CreateStore(ConstantInt::get(ITy, Fill), Dest,
181                                        MI->isVolatile());
182    S->setAlignment(Alignment);
183
184    // Set the size of the copy to 0, it will be deleted on the next iteration.
185    MI->setLength(Constant::getNullValue(LenC->getType()));
186    return MI;
187  }
188
189  return 0;
190}
191
192/// visitCallInst - CallInst simplification.  This mostly only handles folding
193/// of intrinsic instructions.  For normal calls, it allows visitCallSite to do
194/// the heavy lifting.
195///
196Instruction *InstCombiner::visitCallInst(CallInst &CI) {
197  if (isFreeCall(&CI, TLI))
198    return visitFree(CI);
199
200  // If the caller function is nounwind, mark the call as nounwind, even if the
201  // callee isn't.
202  if (CI.getParent()->getParent()->doesNotThrow() &&
203      !CI.doesNotThrow()) {
204    CI.setDoesNotThrow();
205    return &CI;
206  }
207
208  IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
209  if (!II) return visitCallSite(&CI);
210
211  // Intrinsics cannot occur in an invoke, so handle them here instead of in
212  // visitCallSite.
213  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
214    bool Changed = false;
215
216    // memmove/cpy/set of zero bytes is a noop.
217    if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
218      if (NumBytes->isNullValue())
219        return EraseInstFromFunction(CI);
220
221      if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
222        if (CI->getZExtValue() == 1) {
223          // Replace the instruction with just byte operations.  We would
224          // transform other cases to loads/stores, but we don't know if
225          // alignment is sufficient.
226        }
227    }
228
229    // No other transformations apply to volatile transfers.
230    if (MI->isVolatile())
231      return 0;
232
233    // If we have a memmove and the source operation is a constant global,
234    // then the source and dest pointers can't alias, so we can change this
235    // into a call to memcpy.
236    if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
237      if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
238        if (GVSrc->isConstant()) {
239          Module *M = CI.getParent()->getParent()->getParent();
240          Intrinsic::ID MemCpyID = Intrinsic::memcpy;
241          Type *Tys[3] = { CI.getArgOperand(0)->getType(),
242                           CI.getArgOperand(1)->getType(),
243                           CI.getArgOperand(2)->getType() };
244          CI.setCalledFunction(Intrinsic::getDeclaration(M, MemCpyID, Tys));
245          Changed = true;
246        }
247    }
248
249    if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) {
250      // memmove(x,x,size) -> noop.
251      if (MTI->getSource() == MTI->getDest())
252        return EraseInstFromFunction(CI);
253    }
254
255    // If we can determine a pointer alignment that is bigger than currently
256    // set, update the alignment.
257    if (isa<MemTransferInst>(MI)) {
258      if (Instruction *I = SimplifyMemTransfer(MI))
259        return I;
260    } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
261      if (Instruction *I = SimplifyMemSet(MSI))
262        return I;
263    }
264
265    if (Changed) return II;
266  }
267
268  switch (II->getIntrinsicID()) {
269  default: break;
270  case Intrinsic::objectsize: {
271    uint64_t Size;
272    if (getObjectSize(II->getArgOperand(0), Size, TD, TLI))
273      return ReplaceInstUsesWith(CI, ConstantInt::get(CI.getType(), Size));
274    return 0;
275  }
276  case Intrinsic::bswap:
277    // bswap(bswap(x)) -> x
278    if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getArgOperand(0)))
279      if (Operand->getIntrinsicID() == Intrinsic::bswap)
280        return ReplaceInstUsesWith(CI, Operand->getArgOperand(0));
281
282    // bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
283    if (TruncInst *TI = dyn_cast<TruncInst>(II->getArgOperand(0))) {
284      if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(TI->getOperand(0)))
285        if (Operand->getIntrinsicID() == Intrinsic::bswap) {
286          unsigned C = Operand->getType()->getPrimitiveSizeInBits() -
287                       TI->getType()->getPrimitiveSizeInBits();
288          Value *CV = ConstantInt::get(Operand->getType(), C);
289          Value *V = Builder->CreateLShr(Operand->getArgOperand(0), CV);
290          return new TruncInst(V, TI->getType());
291        }
292    }
293
294    break;
295  case Intrinsic::powi:
296    if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
297      // powi(x, 0) -> 1.0
298      if (Power->isZero())
299        return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
300      // powi(x, 1) -> x
301      if (Power->isOne())
302        return ReplaceInstUsesWith(CI, II->getArgOperand(0));
303      // powi(x, -1) -> 1/x
304      if (Power->isAllOnesValue())
305        return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
306                                          II->getArgOperand(0));
307    }
308    break;
309  case Intrinsic::cttz: {
310    // If all bits below the first known one are known zero,
311    // this value is constant.
312    IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
313    // FIXME: Try to simplify vectors of integers.
314    if (!IT) break;
315    uint32_t BitWidth = IT->getBitWidth();
316    APInt KnownZero(BitWidth, 0);
317    APInt KnownOne(BitWidth, 0);
318    ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
319    unsigned TrailingZeros = KnownOne.countTrailingZeros();
320    APInt Mask(APInt::getLowBitsSet(BitWidth, TrailingZeros));
321    if ((Mask & KnownZero) == Mask)
322      return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
323                                 APInt(BitWidth, TrailingZeros)));
324
325    }
326    break;
327  case Intrinsic::ctlz: {
328    // If all bits above the first known one are known zero,
329    // this value is constant.
330    IntegerType *IT = dyn_cast<IntegerType>(II->getArgOperand(0)->getType());
331    // FIXME: Try to simplify vectors of integers.
332    if (!IT) break;
333    uint32_t BitWidth = IT->getBitWidth();
334    APInt KnownZero(BitWidth, 0);
335    APInt KnownOne(BitWidth, 0);
336    ComputeMaskedBits(II->getArgOperand(0), KnownZero, KnownOne);
337    unsigned LeadingZeros = KnownOne.countLeadingZeros();
338    APInt Mask(APInt::getHighBitsSet(BitWidth, LeadingZeros));
339    if ((Mask & KnownZero) == Mask)
340      return ReplaceInstUsesWith(CI, ConstantInt::get(IT,
341                                 APInt(BitWidth, LeadingZeros)));
342
343    }
344    break;
345  case Intrinsic::uadd_with_overflow: {
346    Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
347    IntegerType *IT = cast<IntegerType>(II->getArgOperand(0)->getType());
348    uint32_t BitWidth = IT->getBitWidth();
349    APInt LHSKnownZero(BitWidth, 0);
350    APInt LHSKnownOne(BitWidth, 0);
351    ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
352    bool LHSKnownNegative = LHSKnownOne[BitWidth - 1];
353    bool LHSKnownPositive = LHSKnownZero[BitWidth - 1];
354
355    if (LHSKnownNegative || LHSKnownPositive) {
356      APInt RHSKnownZero(BitWidth, 0);
357      APInt RHSKnownOne(BitWidth, 0);
358      ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
359      bool RHSKnownNegative = RHSKnownOne[BitWidth - 1];
360      bool RHSKnownPositive = RHSKnownZero[BitWidth - 1];
361      if (LHSKnownNegative && RHSKnownNegative) {
362        // The sign bit is set in both cases: this MUST overflow.
363        // Create a simple add instruction, and insert it into the struct.
364        Value *Add = Builder->CreateAdd(LHS, RHS);
365        Add->takeName(&CI);
366        Constant *V[] = {
367          UndefValue::get(LHS->getType()),
368          ConstantInt::getTrue(II->getContext())
369        };
370        StructType *ST = cast<StructType>(II->getType());
371        Constant *Struct = ConstantStruct::get(ST, V);
372        return InsertValueInst::Create(Struct, Add, 0);
373      }
374
375      if (LHSKnownPositive && RHSKnownPositive) {
376        // The sign bit is clear in both cases: this CANNOT overflow.
377        // Create a simple add instruction, and insert it into the struct.
378        Value *Add = Builder->CreateNUWAdd(LHS, RHS);
379        Add->takeName(&CI);
380        Constant *V[] = {
381          UndefValue::get(LHS->getType()),
382          ConstantInt::getFalse(II->getContext())
383        };
384        StructType *ST = cast<StructType>(II->getType());
385        Constant *Struct = ConstantStruct::get(ST, V);
386        return InsertValueInst::Create(Struct, Add, 0);
387      }
388    }
389  }
390  // FALL THROUGH uadd into sadd
391  case Intrinsic::sadd_with_overflow:
392    // Canonicalize constants into the RHS.
393    if (isa<Constant>(II->getArgOperand(0)) &&
394        !isa<Constant>(II->getArgOperand(1))) {
395      Value *LHS = II->getArgOperand(0);
396      II->setArgOperand(0, II->getArgOperand(1));
397      II->setArgOperand(1, LHS);
398      return II;
399    }
400
401    // X + undef -> undef
402    if (isa<UndefValue>(II->getArgOperand(1)))
403      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
404
405    if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
406      // X + 0 -> {X, false}
407      if (RHS->isZero()) {
408        Constant *V[] = {
409          UndefValue::get(II->getArgOperand(0)->getType()),
410          ConstantInt::getFalse(II->getContext())
411        };
412        Constant *Struct =
413          ConstantStruct::get(cast<StructType>(II->getType()), V);
414        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
415      }
416    }
417    break;
418  case Intrinsic::usub_with_overflow:
419  case Intrinsic::ssub_with_overflow:
420    // undef - X -> undef
421    // X - undef -> undef
422    if (isa<UndefValue>(II->getArgOperand(0)) ||
423        isa<UndefValue>(II->getArgOperand(1)))
424      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
425
426    if (ConstantInt *RHS = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
427      // X - 0 -> {X, false}
428      if (RHS->isZero()) {
429        Constant *V[] = {
430          UndefValue::get(II->getArgOperand(0)->getType()),
431          ConstantInt::getFalse(II->getContext())
432        };
433        Constant *Struct =
434          ConstantStruct::get(cast<StructType>(II->getType()), V);
435        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
436      }
437    }
438    break;
439  case Intrinsic::umul_with_overflow: {
440    Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
441    unsigned BitWidth = cast<IntegerType>(LHS->getType())->getBitWidth();
442
443    APInt LHSKnownZero(BitWidth, 0);
444    APInt LHSKnownOne(BitWidth, 0);
445    ComputeMaskedBits(LHS, LHSKnownZero, LHSKnownOne);
446    APInt RHSKnownZero(BitWidth, 0);
447    APInt RHSKnownOne(BitWidth, 0);
448    ComputeMaskedBits(RHS, RHSKnownZero, RHSKnownOne);
449
450    // Get the largest possible values for each operand.
451    APInt LHSMax = ~LHSKnownZero;
452    APInt RHSMax = ~RHSKnownZero;
453
454    // If multiplying the maximum values does not overflow then we can turn
455    // this into a plain NUW mul.
456    bool Overflow;
457    LHSMax.umul_ov(RHSMax, Overflow);
458    if (!Overflow) {
459      Value *Mul = Builder->CreateNUWMul(LHS, RHS, "umul_with_overflow");
460      Constant *V[] = {
461        UndefValue::get(LHS->getType()),
462        Builder->getFalse()
463      };
464      Constant *Struct = ConstantStruct::get(cast<StructType>(II->getType()),V);
465      return InsertValueInst::Create(Struct, Mul, 0);
466    }
467  } // FALL THROUGH
468  case Intrinsic::smul_with_overflow:
469    // Canonicalize constants into the RHS.
470    if (isa<Constant>(II->getArgOperand(0)) &&
471        !isa<Constant>(II->getArgOperand(1))) {
472      Value *LHS = II->getArgOperand(0);
473      II->setArgOperand(0, II->getArgOperand(1));
474      II->setArgOperand(1, LHS);
475      return II;
476    }
477
478    // X * undef -> undef
479    if (isa<UndefValue>(II->getArgOperand(1)))
480      return ReplaceInstUsesWith(CI, UndefValue::get(II->getType()));
481
482    if (ConstantInt *RHSI = dyn_cast<ConstantInt>(II->getArgOperand(1))) {
483      // X*0 -> {0, false}
484      if (RHSI->isZero())
485        return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType()));
486
487      // X * 1 -> {X, false}
488      if (RHSI->equalsInt(1)) {
489        Constant *V[] = {
490          UndefValue::get(II->getArgOperand(0)->getType()),
491          ConstantInt::getFalse(II->getContext())
492        };
493        Constant *Struct =
494          ConstantStruct::get(cast<StructType>(II->getType()), V);
495        return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
496      }
497    }
498    break;
499  case Intrinsic::ppc_altivec_lvx:
500  case Intrinsic::ppc_altivec_lvxl:
501    // Turn PPC lvx -> load if the pointer is known aligned.
502    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
503      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0),
504                                         PointerType::getUnqual(II->getType()));
505      return new LoadInst(Ptr);
506    }
507    break;
508  case Intrinsic::ppc_altivec_stvx:
509  case Intrinsic::ppc_altivec_stvxl:
510    // Turn stvx -> store if the pointer is known aligned.
511    if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, TD) >= 16) {
512      Type *OpPtrTy =
513        PointerType::getUnqual(II->getArgOperand(0)->getType());
514      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy);
515      return new StoreInst(II->getArgOperand(0), Ptr);
516    }
517    break;
518  case Intrinsic::x86_sse_storeu_ps:
519  case Intrinsic::x86_sse2_storeu_pd:
520  case Intrinsic::x86_sse2_storeu_dq:
521    // Turn X86 storeu -> store if the pointer is known aligned.
522    if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, TD) >= 16) {
523      Type *OpPtrTy =
524        PointerType::getUnqual(II->getArgOperand(1)->getType());
525      Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy);
526      return new StoreInst(II->getArgOperand(1), Ptr);
527    }
528    break;
529
530  case Intrinsic::x86_sse_cvtss2si:
531  case Intrinsic::x86_sse_cvtss2si64:
532  case Intrinsic::x86_sse_cvttss2si:
533  case Intrinsic::x86_sse_cvttss2si64:
534  case Intrinsic::x86_sse2_cvtsd2si:
535  case Intrinsic::x86_sse2_cvtsd2si64:
536  case Intrinsic::x86_sse2_cvttsd2si:
537  case Intrinsic::x86_sse2_cvttsd2si64: {
538    // These intrinsics only demand the 0th element of their input vectors. If
539    // we can simplify the input based on that, do so now.
540    unsigned VWidth =
541      cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
542    APInt DemandedElts(VWidth, 1);
543    APInt UndefElts(VWidth, 0);
544    if (Value *V = SimplifyDemandedVectorElts(II->getArgOperand(0),
545                                              DemandedElts, UndefElts)) {
546      II->setArgOperand(0, V);
547      return II;
548    }
549    break;
550  }
551
552
553  case Intrinsic::x86_sse41_pmovsxbw:
554  case Intrinsic::x86_sse41_pmovsxwd:
555  case Intrinsic::x86_sse41_pmovsxdq:
556  case Intrinsic::x86_sse41_pmovzxbw:
557  case Intrinsic::x86_sse41_pmovzxwd:
558  case Intrinsic::x86_sse41_pmovzxdq: {
559    // pmov{s|z}x ignores the upper half of their input vectors.
560    unsigned VWidth =
561      cast<VectorType>(II->getArgOperand(0)->getType())->getNumElements();
562    unsigned LowHalfElts = VWidth / 2;
563    APInt InputDemandedElts(APInt::getBitsSet(VWidth, 0, LowHalfElts));
564    APInt UndefElts(VWidth, 0);
565    if (Value *TmpV = SimplifyDemandedVectorElts(II->getArgOperand(0),
566                                                 InputDemandedElts,
567                                                 UndefElts)) {
568      II->setArgOperand(0, TmpV);
569      return II;
570    }
571    break;
572  }
573
574  case Intrinsic::ppc_altivec_vperm:
575    // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
576    if (Constant *Mask = dyn_cast<Constant>(II->getArgOperand(2))) {
577      assert(Mask->getType()->getVectorNumElements() == 16 &&
578             "Bad type for intrinsic!");
579
580      // Check that all of the elements are integer constants or undefs.
581      bool AllEltsOk = true;
582      for (unsigned i = 0; i != 16; ++i) {
583        Constant *Elt = Mask->getAggregateElement(i);
584        if (Elt == 0 ||
585            !(isa<ConstantInt>(Elt) || isa<UndefValue>(Elt))) {
586          AllEltsOk = false;
587          break;
588        }
589      }
590
591      if (AllEltsOk) {
592        // Cast the input vectors to byte vectors.
593        Value *Op0 = Builder->CreateBitCast(II->getArgOperand(0),
594                                            Mask->getType());
595        Value *Op1 = Builder->CreateBitCast(II->getArgOperand(1),
596                                            Mask->getType());
597        Value *Result = UndefValue::get(Op0->getType());
598
599        // Only extract each element once.
600        Value *ExtractedElts[32];
601        memset(ExtractedElts, 0, sizeof(ExtractedElts));
602
603        for (unsigned i = 0; i != 16; ++i) {
604          if (isa<UndefValue>(Mask->getAggregateElement(i)))
605            continue;
606          unsigned Idx =
607            cast<ConstantInt>(Mask->getAggregateElement(i))->getZExtValue();
608          Idx &= 31;  // Match the hardware behavior.
609
610          if (ExtractedElts[Idx] == 0) {
611            ExtractedElts[Idx] =
612              Builder->CreateExtractElement(Idx < 16 ? Op0 : Op1,
613                                            Builder->getInt32(Idx&15));
614          }
615
616          // Insert this value into the result vector.
617          Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx],
618                                                Builder->getInt32(i));
619        }
620        return CastInst::Create(Instruction::BitCast, Result, CI.getType());
621      }
622    }
623    break;
624
625  case Intrinsic::arm_neon_vld1:
626  case Intrinsic::arm_neon_vld2:
627  case Intrinsic::arm_neon_vld3:
628  case Intrinsic::arm_neon_vld4:
629  case Intrinsic::arm_neon_vld2lane:
630  case Intrinsic::arm_neon_vld3lane:
631  case Intrinsic::arm_neon_vld4lane:
632  case Intrinsic::arm_neon_vst1:
633  case Intrinsic::arm_neon_vst2:
634  case Intrinsic::arm_neon_vst3:
635  case Intrinsic::arm_neon_vst4:
636  case Intrinsic::arm_neon_vst2lane:
637  case Intrinsic::arm_neon_vst3lane:
638  case Intrinsic::arm_neon_vst4lane: {
639    unsigned MemAlign = getKnownAlignment(II->getArgOperand(0), TD);
640    unsigned AlignArg = II->getNumArgOperands() - 1;
641    ConstantInt *IntrAlign = dyn_cast<ConstantInt>(II->getArgOperand(AlignArg));
642    if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) {
643      II->setArgOperand(AlignArg,
644                        ConstantInt::get(Type::getInt32Ty(II->getContext()),
645                                         MemAlign, false));
646      return II;
647    }
648    break;
649  }
650
651  case Intrinsic::arm_neon_vmulls:
652  case Intrinsic::arm_neon_vmullu: {
653    Value *Arg0 = II->getArgOperand(0);
654    Value *Arg1 = II->getArgOperand(1);
655
656    // Handle mul by zero first:
657    if (isa<ConstantAggregateZero>(Arg0) || isa<ConstantAggregateZero>(Arg1)) {
658      return ReplaceInstUsesWith(CI, ConstantAggregateZero::get(II->getType()));
659    }
660
661    // Check for constant LHS & RHS - in this case we just simplify.
662    bool Zext = (II->getIntrinsicID() == Intrinsic::arm_neon_vmullu);
663    VectorType *NewVT = cast<VectorType>(II->getType());
664    unsigned NewWidth = NewVT->getElementType()->getIntegerBitWidth();
665    if (ConstantDataVector *CV0 = dyn_cast<ConstantDataVector>(Arg0)) {
666      if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
667        VectorType* VT = cast<VectorType>(CV0->getType());
668        SmallVector<Constant*, 4> NewElems;
669        for (unsigned i = 0; i < VT->getNumElements(); ++i) {
670          APInt CV0E =
671            (cast<ConstantInt>(CV0->getAggregateElement(i)))->getValue();
672          CV0E = Zext ? CV0E.zext(NewWidth) : CV0E.sext(NewWidth);
673          APInt CV1E =
674            (cast<ConstantInt>(CV1->getAggregateElement(i)))->getValue();
675          CV1E = Zext ? CV1E.zext(NewWidth) : CV1E.sext(NewWidth);
676          NewElems.push_back(
677            ConstantInt::get(NewVT->getElementType(), CV0E * CV1E));
678        }
679        return ReplaceInstUsesWith(CI, ConstantVector::get(NewElems));
680      }
681
682      // Couldn't simplify - cannonicalize constant to the RHS.
683      std::swap(Arg0, Arg1);
684    }
685
686    // Handle mul by one:
687    if (ConstantDataVector *CV1 = dyn_cast<ConstantDataVector>(Arg1)) {
688      if (ConstantInt *Splat =
689            dyn_cast_or_null<ConstantInt>(CV1->getSplatValue())) {
690        if (Splat->isOne()) {
691          if (Zext)
692            return CastInst::CreateZExtOrBitCast(Arg0, II->getType());
693          // else
694          return CastInst::CreateSExtOrBitCast(Arg0, II->getType());
695        }
696      }
697    }
698
699    break;
700  }
701
702  case Intrinsic::stackrestore: {
703    // If the save is right next to the restore, remove the restore.  This can
704    // happen when variable allocas are DCE'd.
705    if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getArgOperand(0))) {
706      if (SS->getIntrinsicID() == Intrinsic::stacksave) {
707        BasicBlock::iterator BI = SS;
708        if (&*++BI == II)
709          return EraseInstFromFunction(CI);
710      }
711    }
712
713    // Scan down this block to see if there is another stack restore in the
714    // same block without an intervening call/alloca.
715    BasicBlock::iterator BI = II;
716    TerminatorInst *TI = II->getParent()->getTerminator();
717    bool CannotRemove = false;
718    for (++BI; &*BI != TI; ++BI) {
719      if (isa<AllocaInst>(BI)) {
720        CannotRemove = true;
721        break;
722      }
723      if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
724        if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
725          // If there is a stackrestore below this one, remove this one.
726          if (II->getIntrinsicID() == Intrinsic::stackrestore)
727            return EraseInstFromFunction(CI);
728          // Otherwise, ignore the intrinsic.
729        } else {
730          // If we found a non-intrinsic call, we can't remove the stack
731          // restore.
732          CannotRemove = true;
733          break;
734        }
735      }
736    }
737
738    // If the stack restore is in a return, resume, or unwind block and if there
739    // are no allocas or calls between the restore and the return, nuke the
740    // restore.
741    if (!CannotRemove && (isa<ReturnInst>(TI) || isa<ResumeInst>(TI)))
742      return EraseInstFromFunction(CI);
743    break;
744  }
745  }
746
747  return visitCallSite(II);
748}
749
750// InvokeInst simplification
751//
752Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
753  return visitCallSite(&II);
754}
755
756/// isSafeToEliminateVarargsCast - If this cast does not affect the value
757/// passed through the varargs area, we can eliminate the use of the cast.
758static bool isSafeToEliminateVarargsCast(const CallSite CS,
759                                         const CastInst * const CI,
760                                         const DataLayout * const TD,
761                                         const int ix) {
762  if (!CI->isLosslessCast())
763    return false;
764
765  // The size of ByVal arguments is derived from the type, so we
766  // can't change to a type with a different size.  If the size were
767  // passed explicitly we could avoid this check.
768  if (!CS.isByValArgument(ix))
769    return true;
770
771  Type* SrcTy =
772            cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
773  Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
774  if (!SrcTy->isSized() || !DstTy->isSized())
775    return false;
776  if (!TD || TD->getTypeAllocSize(SrcTy) != TD->getTypeAllocSize(DstTy))
777    return false;
778  return true;
779}
780
781// Try to fold some different type of calls here.
782// Currently we're only working with the checking functions, memcpy_chk,
783// mempcpy_chk, memmove_chk, memset_chk, strcpy_chk, stpcpy_chk, strncpy_chk,
784// strcat_chk and strncat_chk.
785Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const DataLayout *TD) {
786  if (CI->getCalledFunction() == 0) return 0;
787
788  if (Value *With = Simplifier->optimizeCall(CI))
789    return ReplaceInstUsesWith(*CI, With);
790
791  return 0;
792}
793
794static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) {
795  // Strip off at most one level of pointer casts, looking for an alloca.  This
796  // is good enough in practice and simpler than handling any number of casts.
797  Value *Underlying = TrampMem->stripPointerCasts();
798  if (Underlying != TrampMem &&
799      (!Underlying->hasOneUse() || *Underlying->use_begin() != TrampMem))
800    return 0;
801  if (!isa<AllocaInst>(Underlying))
802    return 0;
803
804  IntrinsicInst *InitTrampoline = 0;
805  for (Value::use_iterator I = TrampMem->use_begin(), E = TrampMem->use_end();
806       I != E; I++) {
807    IntrinsicInst *II = dyn_cast<IntrinsicInst>(*I);
808    if (!II)
809      return 0;
810    if (II->getIntrinsicID() == Intrinsic::init_trampoline) {
811      if (InitTrampoline)
812        // More than one init_trampoline writes to this value.  Give up.
813        return 0;
814      InitTrampoline = II;
815      continue;
816    }
817    if (II->getIntrinsicID() == Intrinsic::adjust_trampoline)
818      // Allow any number of calls to adjust.trampoline.
819      continue;
820    return 0;
821  }
822
823  // No call to init.trampoline found.
824  if (!InitTrampoline)
825    return 0;
826
827  // Check that the alloca is being used in the expected way.
828  if (InitTrampoline->getOperand(0) != TrampMem)
829    return 0;
830
831  return InitTrampoline;
832}
833
834static IntrinsicInst *FindInitTrampolineFromBB(IntrinsicInst *AdjustTramp,
835                                               Value *TrampMem) {
836  // Visit all the previous instructions in the basic block, and try to find a
837  // init.trampoline which has a direct path to the adjust.trampoline.
838  for (BasicBlock::iterator I = AdjustTramp,
839       E = AdjustTramp->getParent()->begin(); I != E; ) {
840    Instruction *Inst = --I;
841    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
842      if (II->getIntrinsicID() == Intrinsic::init_trampoline &&
843          II->getOperand(0) == TrampMem)
844        return II;
845    if (Inst->mayWriteToMemory())
846      return 0;
847  }
848  return 0;
849}
850
851// Given a call to llvm.adjust.trampoline, find and return the corresponding
852// call to llvm.init.trampoline if the call to the trampoline can be optimized
853// to a direct call to a function.  Otherwise return NULL.
854//
855static IntrinsicInst *FindInitTrampoline(Value *Callee) {
856  Callee = Callee->stripPointerCasts();
857  IntrinsicInst *AdjustTramp = dyn_cast<IntrinsicInst>(Callee);
858  if (!AdjustTramp ||
859      AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline)
860    return 0;
861
862  Value *TrampMem = AdjustTramp->getOperand(0);
863
864  if (IntrinsicInst *IT = FindInitTrampolineFromAlloca(TrampMem))
865    return IT;
866  if (IntrinsicInst *IT = FindInitTrampolineFromBB(AdjustTramp, TrampMem))
867    return IT;
868  return 0;
869}
870
871// visitCallSite - Improvements for call and invoke instructions.
872//
873Instruction *InstCombiner::visitCallSite(CallSite CS) {
874  if (isAllocLikeFn(CS.getInstruction(), TLI))
875    return visitAllocSite(*CS.getInstruction());
876
877  bool Changed = false;
878
879  // If the callee is a pointer to a function, attempt to move any casts to the
880  // arguments of the call/invoke.
881  Value *Callee = CS.getCalledValue();
882  if (!isa<Function>(Callee) && transformConstExprCastCall(CS))
883    return 0;
884
885  if (Function *CalleeF = dyn_cast<Function>(Callee))
886    // If the call and callee calling conventions don't match, this call must
887    // be unreachable, as the call is undefined.
888    if (CalleeF->getCallingConv() != CS.getCallingConv() &&
889        // Only do this for calls to a function with a body.  A prototype may
890        // not actually end up matching the implementation's calling conv for a
891        // variety of reasons (e.g. it may be written in assembly).
892        !CalleeF->isDeclaration()) {
893      Instruction *OldCall = CS.getInstruction();
894      new StoreInst(ConstantInt::getTrue(Callee->getContext()),
895                UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
896                                  OldCall);
897      // If OldCall dues not return void then replaceAllUsesWith undef.
898      // This allows ValueHandlers and custom metadata to adjust itself.
899      if (!OldCall->getType()->isVoidTy())
900        ReplaceInstUsesWith(*OldCall, UndefValue::get(OldCall->getType()));
901      if (isa<CallInst>(OldCall))
902        return EraseInstFromFunction(*OldCall);
903
904      // We cannot remove an invoke, because it would change the CFG, just
905      // change the callee to a null pointer.
906      cast<InvokeInst>(OldCall)->setCalledFunction(
907                                    Constant::getNullValue(CalleeF->getType()));
908      return 0;
909    }
910
911  if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
912    // If CS does not return void then replaceAllUsesWith undef.
913    // This allows ValueHandlers and custom metadata to adjust itself.
914    if (!CS.getInstruction()->getType()->isVoidTy())
915      ReplaceInstUsesWith(*CS.getInstruction(),
916                          UndefValue::get(CS.getInstruction()->getType()));
917
918    if (isa<InvokeInst>(CS.getInstruction())) {
919      // Can't remove an invoke because we cannot change the CFG.
920      return 0;
921    }
922
923    // This instruction is not reachable, just remove it.  We insert a store to
924    // undef so that we know that this code is not reachable, despite the fact
925    // that we can't modify the CFG here.
926    new StoreInst(ConstantInt::getTrue(Callee->getContext()),
927                  UndefValue::get(Type::getInt1PtrTy(Callee->getContext())),
928                  CS.getInstruction());
929
930    return EraseInstFromFunction(*CS.getInstruction());
931  }
932
933  if (IntrinsicInst *II = FindInitTrampoline(Callee))
934    return transformCallThroughTrampoline(CS, II);
935
936  PointerType *PTy = cast<PointerType>(Callee->getType());
937  FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
938  if (FTy->isVarArg()) {
939    int ix = FTy->getNumParams();
940    // See if we can optimize any arguments passed through the varargs area of
941    // the call.
942    for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
943           E = CS.arg_end(); I != E; ++I, ++ix) {
944      CastInst *CI = dyn_cast<CastInst>(*I);
945      if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
946        *I = CI->getOperand(0);
947        Changed = true;
948      }
949    }
950  }
951
952  if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
953    // Inline asm calls cannot throw - mark them 'nounwind'.
954    CS.setDoesNotThrow();
955    Changed = true;
956  }
957
958  // Try to optimize the call if possible, we require DataLayout for most of
959  // this.  None of these calls are seen as possibly dead so go ahead and
960  // delete the instruction now.
961  if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
962    Instruction *I = tryOptimizeCall(CI, TD);
963    // If we changed something return the result, etc. Otherwise let
964    // the fallthrough check.
965    if (I) return EraseInstFromFunction(*I);
966  }
967
968  return Changed ? CS.getInstruction() : 0;
969}
970
971// transformConstExprCastCall - If the callee is a constexpr cast of a function,
972// attempt to move the cast to the arguments of the call/invoke.
973//
974bool InstCombiner::transformConstExprCastCall(CallSite CS) {
975  Function *Callee =
976    dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
977  if (Callee == 0)
978    return false;
979  Instruction *Caller = CS.getInstruction();
980  const AttrListPtr &CallerPAL = CS.getAttributes();
981
982  // Okay, this is a cast from a function to a different type.  Unless doing so
983  // would cause a type conversion of one of our arguments, change this call to
984  // be a direct call with arguments casted to the appropriate types.
985  //
986  FunctionType *FT = Callee->getFunctionType();
987  Type *OldRetTy = Caller->getType();
988  Type *NewRetTy = FT->getReturnType();
989
990  if (NewRetTy->isStructTy())
991    return false; // TODO: Handle multiple return values.
992
993  // Check to see if we are changing the return type...
994  if (OldRetTy != NewRetTy) {
995    if (Callee->isDeclaration() &&
996        // Conversion is ok if changing from one pointer type to another or from
997        // a pointer to an integer of the same size.
998        !((OldRetTy->isPointerTy() || !TD ||
999           OldRetTy == TD->getIntPtrType(Caller->getContext())) &&
1000          (NewRetTy->isPointerTy() || !TD ||
1001           NewRetTy == TD->getIntPtrType(Caller->getContext()))))
1002      return false;   // Cannot transform this return value.
1003
1004    if (!Caller->use_empty() &&
1005        // void -> non-void is handled specially
1006        !NewRetTy->isVoidTy() && !CastInst::isCastable(NewRetTy, OldRetTy))
1007      return false;   // Cannot transform this return value.
1008
1009    if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
1010      AttrBuilder RAttrs = CallerPAL.getRetAttributes();
1011      if (RAttrs.hasAttributes(Attributes::typeIncompatible(NewRetTy)))
1012        return false;   // Attribute not compatible with transformed value.
1013    }
1014
1015    // If the callsite is an invoke instruction, and the return value is used by
1016    // a PHI node in a successor, we cannot change the return type of the call
1017    // because there is no place to put the cast instruction (without breaking
1018    // the critical edge).  Bail out in this case.
1019    if (!Caller->use_empty())
1020      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
1021        for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
1022             UI != E; ++UI)
1023          if (PHINode *PN = dyn_cast<PHINode>(*UI))
1024            if (PN->getParent() == II->getNormalDest() ||
1025                PN->getParent() == II->getUnwindDest())
1026              return false;
1027  }
1028
1029  unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
1030  unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
1031
1032  CallSite::arg_iterator AI = CS.arg_begin();
1033  for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
1034    Type *ParamTy = FT->getParamType(i);
1035    Type *ActTy = (*AI)->getType();
1036
1037    if (!CastInst::isCastable(ActTy, ParamTy))
1038      return false;   // Cannot transform this parameter value.
1039
1040    Attributes Attrs = CallerPAL.getParamAttributes(i + 1);
1041    if (AttrBuilder(Attrs).
1042          hasAttributes(Attributes::typeIncompatible(ParamTy)))
1043      return false;   // Attribute not compatible with transformed value.
1044
1045    // If the parameter is passed as a byval argument, then we have to have a
1046    // sized type and the sized type has to have the same size as the old type.
1047    if (ParamTy != ActTy && Attrs.hasAttribute(Attributes::ByVal)) {
1048      PointerType *ParamPTy = dyn_cast<PointerType>(ParamTy);
1049      if (ParamPTy == 0 || !ParamPTy->getElementType()->isSized() || TD == 0)
1050        return false;
1051
1052      Type *CurElTy = cast<PointerType>(ActTy)->getElementType();
1053      if (TD->getTypeAllocSize(CurElTy) !=
1054          TD->getTypeAllocSize(ParamPTy->getElementType()))
1055        return false;
1056    }
1057
1058    // Converting from one pointer type to another or between a pointer and an
1059    // integer of the same size is safe even if we do not have a body.
1060    bool isConvertible = ActTy == ParamTy ||
1061      (TD && ((ParamTy->isPointerTy() ||
1062      ParamTy == TD->getIntPtrType(Caller->getContext())) &&
1063              (ActTy->isPointerTy() ||
1064              ActTy == TD->getIntPtrType(Caller->getContext()))));
1065    if (Callee->isDeclaration() && !isConvertible) return false;
1066  }
1067
1068  if (Callee->isDeclaration()) {
1069    // Do not delete arguments unless we have a function body.
1070    if (FT->getNumParams() < NumActualArgs && !FT->isVarArg())
1071      return false;
1072
1073    // If the callee is just a declaration, don't change the varargsness of the
1074    // call.  We don't want to introduce a varargs call where one doesn't
1075    // already exist.
1076    PointerType *APTy = cast<PointerType>(CS.getCalledValue()->getType());
1077    if (FT->isVarArg()!=cast<FunctionType>(APTy->getElementType())->isVarArg())
1078      return false;
1079
1080    // If both the callee and the cast type are varargs, we still have to make
1081    // sure the number of fixed parameters are the same or we have the same
1082    // ABI issues as if we introduce a varargs call.
1083    if (FT->isVarArg() &&
1084        cast<FunctionType>(APTy->getElementType())->isVarArg() &&
1085        FT->getNumParams() !=
1086        cast<FunctionType>(APTy->getElementType())->getNumParams())
1087      return false;
1088  }
1089
1090  if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
1091      !CallerPAL.isEmpty())
1092    // In this case we have more arguments than the new function type, but we
1093    // won't be dropping them.  Check that these extra arguments have attributes
1094    // that are compatible with being a vararg call argument.
1095    for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
1096      if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
1097        break;
1098      Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
1099      if (PAttrs.hasIncompatibleWithVarArgsAttrs())
1100        return false;
1101    }
1102
1103
1104  // Okay, we decided that this is a safe thing to do: go ahead and start
1105  // inserting cast instructions as necessary.
1106  std::vector<Value*> Args;
1107  Args.reserve(NumActualArgs);
1108  SmallVector<AttributeWithIndex, 8> attrVec;
1109  attrVec.reserve(NumCommonArgs);
1110
1111  // Get any return attributes.
1112  AttrBuilder RAttrs = CallerPAL.getRetAttributes();
1113
1114  // If the return value is not being used, the type may not be compatible
1115  // with the existing attributes.  Wipe out any problematic attributes.
1116  RAttrs.removeAttributes(Attributes::typeIncompatible(NewRetTy));
1117
1118  // Add the new return attributes.
1119  if (RAttrs.hasAttributes())
1120    attrVec.push_back(
1121      AttributeWithIndex::get(AttrListPtr::ReturnIndex,
1122                              Attributes::get(FT->getContext(), RAttrs)));
1123
1124  AI = CS.arg_begin();
1125  for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
1126    Type *ParamTy = FT->getParamType(i);
1127    if ((*AI)->getType() == ParamTy) {
1128      Args.push_back(*AI);
1129    } else {
1130      Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
1131          false, ParamTy, false);
1132      Args.push_back(Builder->CreateCast(opcode, *AI, ParamTy));
1133    }
1134
1135    // Add any parameter attributes.
1136    Attributes PAttrs = CallerPAL.getParamAttributes(i + 1);
1137    if (PAttrs.hasAttributes())
1138      attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
1139  }
1140
1141  // If the function takes more arguments than the call was taking, add them
1142  // now.
1143  for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
1144    Args.push_back(Constant::getNullValue(FT->getParamType(i)));
1145
1146  // If we are removing arguments to the function, emit an obnoxious warning.
1147  if (FT->getNumParams() < NumActualArgs) {
1148    if (!FT->isVarArg()) {
1149      errs() << "WARNING: While resolving call to function '"
1150             << Callee->getName() << "' arguments were dropped!\n";
1151    } else {
1152      // Add all of the arguments in their promoted form to the arg list.
1153      for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
1154        Type *PTy = getPromotedType((*AI)->getType());
1155        if (PTy != (*AI)->getType()) {
1156          // Must promote to pass through va_arg area!
1157          Instruction::CastOps opcode =
1158            CastInst::getCastOpcode(*AI, false, PTy, false);
1159          Args.push_back(Builder->CreateCast(opcode, *AI, PTy));
1160        } else {
1161          Args.push_back(*AI);
1162        }
1163
1164        // Add any parameter attributes.
1165        Attributes PAttrs = CallerPAL.getParamAttributes(i + 1);
1166        if (PAttrs.hasAttributes())
1167          attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
1168      }
1169    }
1170  }
1171
1172  Attributes FnAttrs = CallerPAL.getFnAttributes();
1173  if (FnAttrs.hasAttributes())
1174    attrVec.push_back(AttributeWithIndex::get(AttrListPtr::FunctionIndex,
1175                                              FnAttrs));
1176
1177  if (NewRetTy->isVoidTy())
1178    Caller->setName("");   // Void type should not have a name.
1179
1180  const AttrListPtr &NewCallerPAL = AttrListPtr::get(Callee->getContext(),
1181                                                     attrVec);
1182
1183  Instruction *NC;
1184  if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1185    NC = Builder->CreateInvoke(Callee, II->getNormalDest(),
1186                               II->getUnwindDest(), Args);
1187    NC->takeName(II);
1188    cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
1189    cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
1190  } else {
1191    CallInst *CI = cast<CallInst>(Caller);
1192    NC = Builder->CreateCall(Callee, Args);
1193    NC->takeName(CI);
1194    if (CI->isTailCall())
1195      cast<CallInst>(NC)->setTailCall();
1196    cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
1197    cast<CallInst>(NC)->setAttributes(NewCallerPAL);
1198  }
1199
1200  // Insert a cast of the return type as necessary.
1201  Value *NV = NC;
1202  if (OldRetTy != NV->getType() && !Caller->use_empty()) {
1203    if (!NV->getType()->isVoidTy()) {
1204      Instruction::CastOps opcode =
1205        CastInst::getCastOpcode(NC, false, OldRetTy, false);
1206      NV = NC = CastInst::Create(opcode, NC, OldRetTy);
1207      NC->setDebugLoc(Caller->getDebugLoc());
1208
1209      // If this is an invoke instruction, we should insert it after the first
1210      // non-phi, instruction in the normal successor block.
1211      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1212        BasicBlock::iterator I = II->getNormalDest()->getFirstInsertionPt();
1213        InsertNewInstBefore(NC, *I);
1214      } else {
1215        // Otherwise, it's a call, just insert cast right after the call.
1216        InsertNewInstBefore(NC, *Caller);
1217      }
1218      Worklist.AddUsersToWorkList(*Caller);
1219    } else {
1220      NV = UndefValue::get(Caller->getType());
1221    }
1222  }
1223
1224  if (!Caller->use_empty())
1225    ReplaceInstUsesWith(*Caller, NV);
1226
1227  EraseInstFromFunction(*Caller);
1228  return true;
1229}
1230
1231// transformCallThroughTrampoline - Turn a call to a function created by
1232// init_trampoline / adjust_trampoline intrinsic pair into a direct call to the
1233// underlying function.
1234//
1235Instruction *
1236InstCombiner::transformCallThroughTrampoline(CallSite CS,
1237                                             IntrinsicInst *Tramp) {
1238  Value *Callee = CS.getCalledValue();
1239  PointerType *PTy = cast<PointerType>(Callee->getType());
1240  FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
1241  const AttrListPtr &Attrs = CS.getAttributes();
1242
1243  // If the call already has the 'nest' attribute somewhere then give up -
1244  // otherwise 'nest' would occur twice after splicing in the chain.
1245  for (unsigned I = 0, E = Attrs.getNumAttrs(); I != E; ++I)
1246    if (Attrs.getAttributesAtIndex(I).hasAttribute(Attributes::Nest))
1247      return 0;
1248
1249  assert(Tramp &&
1250         "transformCallThroughTrampoline called with incorrect CallSite.");
1251
1252  Function *NestF =cast<Function>(Tramp->getArgOperand(1)->stripPointerCasts());
1253  PointerType *NestFPTy = cast<PointerType>(NestF->getType());
1254  FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
1255
1256  const AttrListPtr &NestAttrs = NestF->getAttributes();
1257  if (!NestAttrs.isEmpty()) {
1258    unsigned NestIdx = 1;
1259    Type *NestTy = 0;
1260    Attributes NestAttr;
1261
1262    // Look for a parameter marked with the 'nest' attribute.
1263    for (FunctionType::param_iterator I = NestFTy->param_begin(),
1264         E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
1265      if (NestAttrs.getParamAttributes(NestIdx).hasAttribute(Attributes::Nest)){
1266        // Record the parameter type and any other attributes.
1267        NestTy = *I;
1268        NestAttr = NestAttrs.getParamAttributes(NestIdx);
1269        break;
1270      }
1271
1272    if (NestTy) {
1273      Instruction *Caller = CS.getInstruction();
1274      std::vector<Value*> NewArgs;
1275      NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
1276
1277      SmallVector<AttributeWithIndex, 8> NewAttrs;
1278      NewAttrs.reserve(Attrs.getNumSlots() + 1);
1279
1280      // Insert the nest argument into the call argument list, which may
1281      // mean appending it.  Likewise for attributes.
1282
1283      // Add any result attributes.
1284      Attributes Attr = Attrs.getRetAttributes();
1285      if (Attr.hasAttributes())
1286        NewAttrs.push_back(AttributeWithIndex::get(AttrListPtr::ReturnIndex,
1287                                                   Attr));
1288
1289      {
1290        unsigned Idx = 1;
1291        CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
1292        do {
1293          if (Idx == NestIdx) {
1294            // Add the chain argument and attributes.
1295            Value *NestVal = Tramp->getArgOperand(2);
1296            if (NestVal->getType() != NestTy)
1297              NestVal = Builder->CreateBitCast(NestVal, NestTy, "nest");
1298            NewArgs.push_back(NestVal);
1299            NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
1300          }
1301
1302          if (I == E)
1303            break;
1304
1305          // Add the original argument and attributes.
1306          NewArgs.push_back(*I);
1307          Attr = Attrs.getParamAttributes(Idx);
1308          if (Attr.hasAttributes())
1309            NewAttrs.push_back
1310              (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
1311
1312          ++Idx, ++I;
1313        } while (1);
1314      }
1315
1316      // Add any function attributes.
1317      Attr = Attrs.getFnAttributes();
1318      if (Attr.hasAttributes())
1319        NewAttrs.push_back(AttributeWithIndex::get(AttrListPtr::FunctionIndex,
1320                                                   Attr));
1321
1322      // The trampoline may have been bitcast to a bogus type (FTy).
1323      // Handle this by synthesizing a new function type, equal to FTy
1324      // with the chain parameter inserted.
1325
1326      std::vector<Type*> NewTypes;
1327      NewTypes.reserve(FTy->getNumParams()+1);
1328
1329      // Insert the chain's type into the list of parameter types, which may
1330      // mean appending it.
1331      {
1332        unsigned Idx = 1;
1333        FunctionType::param_iterator I = FTy->param_begin(),
1334          E = FTy->param_end();
1335
1336        do {
1337          if (Idx == NestIdx)
1338            // Add the chain's type.
1339            NewTypes.push_back(NestTy);
1340
1341          if (I == E)
1342            break;
1343
1344          // Add the original type.
1345          NewTypes.push_back(*I);
1346
1347          ++Idx, ++I;
1348        } while (1);
1349      }
1350
1351      // Replace the trampoline call with a direct call.  Let the generic
1352      // code sort out any function type mismatches.
1353      FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes,
1354                                                FTy->isVarArg());
1355      Constant *NewCallee =
1356        NestF->getType() == PointerType::getUnqual(NewFTy) ?
1357        NestF : ConstantExpr::getBitCast(NestF,
1358                                         PointerType::getUnqual(NewFTy));
1359      const AttrListPtr &NewPAL = AttrListPtr::get(FTy->getContext(), NewAttrs);
1360
1361      Instruction *NewCaller;
1362      if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
1363        NewCaller = InvokeInst::Create(NewCallee,
1364                                       II->getNormalDest(), II->getUnwindDest(),
1365                                       NewArgs);
1366        cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
1367        cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
1368      } else {
1369        NewCaller = CallInst::Create(NewCallee, NewArgs);
1370        if (cast<CallInst>(Caller)->isTailCall())
1371          cast<CallInst>(NewCaller)->setTailCall();
1372        cast<CallInst>(NewCaller)->
1373          setCallingConv(cast<CallInst>(Caller)->getCallingConv());
1374        cast<CallInst>(NewCaller)->setAttributes(NewPAL);
1375      }
1376
1377      return NewCaller;
1378    }
1379  }
1380
1381  // Replace the trampoline call with a direct call.  Since there is no 'nest'
1382  // parameter, there is no need to adjust the argument list.  Let the generic
1383  // code sort out any function type mismatches.
1384  Constant *NewCallee =
1385    NestF->getType() == PTy ? NestF :
1386                              ConstantExpr::getBitCast(NestF, PTy);
1387  CS.setCalledFunction(NewCallee);
1388  return CS.getInstruction();
1389}
1390