1//===-- ConstantFolding.cpp - Fold instructions into constants ------------===//
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 defines routines for folding instructions into constants.
11//
12// Also, to supplement the basic IR ConstantExpr simplifications,
13// this file defines some additional folding routines that can make use of
14// DataLayout information. These functions cannot go in IR due to library
15// dependency issues.
16//
17//===----------------------------------------------------------------------===//
18
19#include "llvm/Analysis/ConstantFolding.h"
20#include "llvm/ADT/STLExtras.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/StringMap.h"
24#include "llvm/Analysis/TargetLibraryInfo.h"
25#include "llvm/Analysis/ValueTracking.h"
26#include "llvm/Config/config.h"
27#include "llvm/IR/Constants.h"
28#include "llvm/IR/DataLayout.h"
29#include "llvm/IR/DerivedTypes.h"
30#include "llvm/IR/Function.h"
31#include "llvm/IR/GetElementPtrTypeIterator.h"
32#include "llvm/IR/GlobalVariable.h"
33#include "llvm/IR/Instructions.h"
34#include "llvm/IR/Intrinsics.h"
35#include "llvm/IR/Operator.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/MathExtras.h"
38#include <cassert>
39#include <cerrno>
40#include <cfenv>
41#include <cmath>
42#include <limits>
43
44using namespace llvm;
45
46namespace {
47
48//===----------------------------------------------------------------------===//
49// Constant Folding internal helper functions
50//===----------------------------------------------------------------------===//
51
52/// Constant fold bitcast, symbolically evaluating it with DataLayout.
53/// This always returns a non-null constant, but it may be a
54/// ConstantExpr if unfoldable.
55Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
56  // Catch the obvious splat cases.
57  if (C->isNullValue() && !DestTy->isX86_MMXTy())
58    return Constant::getNullValue(DestTy);
59  if (C->isAllOnesValue() && !DestTy->isX86_MMXTy() &&
60      !DestTy->isPtrOrPtrVectorTy()) // Don't get ones for ptr types!
61    return Constant::getAllOnesValue(DestTy);
62
63  // Handle a vector->integer cast.
64  if (auto *IT = dyn_cast<IntegerType>(DestTy)) {
65    auto *VTy = dyn_cast<VectorType>(C->getType());
66    if (!VTy)
67      return ConstantExpr::getBitCast(C, DestTy);
68
69    unsigned NumSrcElts = VTy->getNumElements();
70    Type *SrcEltTy = VTy->getElementType();
71
72    // If the vector is a vector of floating point, convert it to vector of int
73    // to simplify things.
74    if (SrcEltTy->isFloatingPointTy()) {
75      unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
76      Type *SrcIVTy =
77        VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElts);
78      // Ask IR to do the conversion now that #elts line up.
79      C = ConstantExpr::getBitCast(C, SrcIVTy);
80    }
81
82    // Now that we know that the input value is a vector of integers, just shift
83    // and insert them into our result.
84    unsigned BitShift = DL.getTypeSizeInBits(SrcEltTy);
85    APInt Result(IT->getBitWidth(), 0);
86    for (unsigned i = 0; i != NumSrcElts; ++i) {
87      Constant *Element;
88      if (DL.isLittleEndian())
89        Element = C->getAggregateElement(NumSrcElts-i-1);
90      else
91        Element = C->getAggregateElement(i);
92
93      auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
94      if (!ElementCI)
95        return ConstantExpr::getBitCast(C, DestTy);
96
97      Result <<= BitShift;
98      Result |= ElementCI->getValue().zextOrSelf(IT->getBitWidth());
99    }
100
101    return ConstantInt::get(IT, Result);
102  }
103
104  // The code below only handles casts to vectors currently.
105  auto *DestVTy = dyn_cast<VectorType>(DestTy);
106  if (!DestVTy)
107    return ConstantExpr::getBitCast(C, DestTy);
108
109  // If this is a scalar -> vector cast, convert the input into a <1 x scalar>
110  // vector so the code below can handle it uniformly.
111  if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
112    Constant *Ops = C; // don't take the address of C!
113    return FoldBitCast(ConstantVector::get(Ops), DestTy, DL);
114  }
115
116  // If this is a bitcast from constant vector -> vector, fold it.
117  if (!isa<ConstantDataVector>(C) && !isa<ConstantVector>(C))
118    return ConstantExpr::getBitCast(C, DestTy);
119
120  // If the element types match, IR can fold it.
121  unsigned NumDstElt = DestVTy->getNumElements();
122  unsigned NumSrcElt = C->getType()->getVectorNumElements();
123  if (NumDstElt == NumSrcElt)
124    return ConstantExpr::getBitCast(C, DestTy);
125
126  Type *SrcEltTy = C->getType()->getVectorElementType();
127  Type *DstEltTy = DestVTy->getElementType();
128
129  // Otherwise, we're changing the number of elements in a vector, which
130  // requires endianness information to do the right thing.  For example,
131  //    bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
132  // folds to (little endian):
133  //    <4 x i32> <i32 0, i32 0, i32 1, i32 0>
134  // and to (big endian):
135  //    <4 x i32> <i32 0, i32 0, i32 0, i32 1>
136
137  // First thing is first.  We only want to think about integer here, so if
138  // we have something in FP form, recast it as integer.
139  if (DstEltTy->isFloatingPointTy()) {
140    // Fold to an vector of integers with same size as our FP type.
141    unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
142    Type *DestIVTy =
143      VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumDstElt);
144    // Recursively handle this integer conversion, if possible.
145    C = FoldBitCast(C, DestIVTy, DL);
146
147    // Finally, IR can handle this now that #elts line up.
148    return ConstantExpr::getBitCast(C, DestTy);
149  }
150
151  // Okay, we know the destination is integer, if the input is FP, convert
152  // it to integer first.
153  if (SrcEltTy->isFloatingPointTy()) {
154    unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
155    Type *SrcIVTy =
156      VectorType::get(IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
157    // Ask IR to do the conversion now that #elts line up.
158    C = ConstantExpr::getBitCast(C, SrcIVTy);
159    // If IR wasn't able to fold it, bail out.
160    if (!isa<ConstantVector>(C) &&  // FIXME: Remove ConstantVector.
161        !isa<ConstantDataVector>(C))
162      return C;
163  }
164
165  // Now we know that the input and output vectors are both integer vectors
166  // of the same size, and that their #elements is not the same.  Do the
167  // conversion here, which depends on whether the input or output has
168  // more elements.
169  bool isLittleEndian = DL.isLittleEndian();
170
171  SmallVector<Constant*, 32> Result;
172  if (NumDstElt < NumSrcElt) {
173    // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
174    Constant *Zero = Constant::getNullValue(DstEltTy);
175    unsigned Ratio = NumSrcElt/NumDstElt;
176    unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
177    unsigned SrcElt = 0;
178    for (unsigned i = 0; i != NumDstElt; ++i) {
179      // Build each element of the result.
180      Constant *Elt = Zero;
181      unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
182      for (unsigned j = 0; j != Ratio; ++j) {
183        Constant *Src = dyn_cast<ConstantInt>(C->getAggregateElement(SrcElt++));
184        if (!Src)  // Reject constantexpr elements.
185          return ConstantExpr::getBitCast(C, DestTy);
186
187        // Zero extend the element to the right size.
188        Src = ConstantExpr::getZExt(Src, Elt->getType());
189
190        // Shift it to the right place, depending on endianness.
191        Src = ConstantExpr::getShl(Src,
192                                   ConstantInt::get(Src->getType(), ShiftAmt));
193        ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
194
195        // Mix it in.
196        Elt = ConstantExpr::getOr(Elt, Src);
197      }
198      Result.push_back(Elt);
199    }
200    return ConstantVector::get(Result);
201  }
202
203  // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
204  unsigned Ratio = NumDstElt/NumSrcElt;
205  unsigned DstBitSize = DL.getTypeSizeInBits(DstEltTy);
206
207  // Loop over each source value, expanding into multiple results.
208  for (unsigned i = 0; i != NumSrcElt; ++i) {
209    auto *Src = dyn_cast<ConstantInt>(C->getAggregateElement(i));
210    if (!Src)  // Reject constantexpr elements.
211      return ConstantExpr::getBitCast(C, DestTy);
212
213    unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
214    for (unsigned j = 0; j != Ratio; ++j) {
215      // Shift the piece of the value into the right place, depending on
216      // endianness.
217      Constant *Elt = ConstantExpr::getLShr(Src,
218                                  ConstantInt::get(Src->getType(), ShiftAmt));
219      ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
220
221      // Truncate the element to an integer with the same pointer size and
222      // convert the element back to a pointer using a inttoptr.
223      if (DstEltTy->isPointerTy()) {
224        IntegerType *DstIntTy = Type::getIntNTy(C->getContext(), DstBitSize);
225        Constant *CE = ConstantExpr::getTrunc(Elt, DstIntTy);
226        Result.push_back(ConstantExpr::getIntToPtr(CE, DstEltTy));
227        continue;
228      }
229
230      // Truncate and remember this piece.
231      Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
232    }
233  }
234
235  return ConstantVector::get(Result);
236}
237
238} // end anonymous namespace
239
240/// If this constant is a constant offset from a global, return the global and
241/// the constant. Because of constantexprs, this function is recursive.
242bool llvm::IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
243                                      APInt &Offset, const DataLayout &DL) {
244  // Trivial case, constant is the global.
245  if ((GV = dyn_cast<GlobalValue>(C))) {
246    unsigned BitWidth = DL.getPointerTypeSizeInBits(GV->getType());
247    Offset = APInt(BitWidth, 0);
248    return true;
249  }
250
251  // Otherwise, if this isn't a constant expr, bail out.
252  auto *CE = dyn_cast<ConstantExpr>(C);
253  if (!CE) return false;
254
255  // Look through ptr->int and ptr->ptr casts.
256  if (CE->getOpcode() == Instruction::PtrToInt ||
257      CE->getOpcode() == Instruction::BitCast)
258    return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, DL);
259
260  // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
261  auto *GEP = dyn_cast<GEPOperator>(CE);
262  if (!GEP)
263    return false;
264
265  unsigned BitWidth = DL.getPointerTypeSizeInBits(GEP->getType());
266  APInt TmpOffset(BitWidth, 0);
267
268  // If the base isn't a global+constant, we aren't either.
269  if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, TmpOffset, DL))
270    return false;
271
272  // Otherwise, add any offset that our operands provide.
273  if (!GEP->accumulateConstantOffset(DL, TmpOffset))
274    return false;
275
276  Offset = TmpOffset;
277  return true;
278}
279
280namespace {
281
282/// Recursive helper to read bits out of global. C is the constant being copied
283/// out of. ByteOffset is an offset into C. CurPtr is the pointer to copy
284/// results into and BytesLeft is the number of bytes left in
285/// the CurPtr buffer. DL is the DataLayout.
286bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset, unsigned char *CurPtr,
287                        unsigned BytesLeft, const DataLayout &DL) {
288  assert(ByteOffset <= DL.getTypeAllocSize(C->getType()) &&
289         "Out of range access");
290
291  // If this element is zero or undefined, we can just return since *CurPtr is
292  // zero initialized.
293  if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C))
294    return true;
295
296  if (auto *CI = dyn_cast<ConstantInt>(C)) {
297    if (CI->getBitWidth() > 64 ||
298        (CI->getBitWidth() & 7) != 0)
299      return false;
300
301    uint64_t Val = CI->getZExtValue();
302    unsigned IntBytes = unsigned(CI->getBitWidth()/8);
303
304    for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) {
305      int n = ByteOffset;
306      if (!DL.isLittleEndian())
307        n = IntBytes - n - 1;
308      CurPtr[i] = (unsigned char)(Val >> (n * 8));
309      ++ByteOffset;
310    }
311    return true;
312  }
313
314  if (auto *CFP = dyn_cast<ConstantFP>(C)) {
315    if (CFP->getType()->isDoubleTy()) {
316      C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), DL);
317      return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
318    }
319    if (CFP->getType()->isFloatTy()){
320      C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), DL);
321      return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
322    }
323    if (CFP->getType()->isHalfTy()){
324      C = FoldBitCast(C, Type::getInt16Ty(C->getContext()), DL);
325      return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
326    }
327    return false;
328  }
329
330  if (auto *CS = dyn_cast<ConstantStruct>(C)) {
331    const StructLayout *SL = DL.getStructLayout(CS->getType());
332    unsigned Index = SL->getElementContainingOffset(ByteOffset);
333    uint64_t CurEltOffset = SL->getElementOffset(Index);
334    ByteOffset -= CurEltOffset;
335
336    while (1) {
337      // If the element access is to the element itself and not to tail padding,
338      // read the bytes from the element.
339      uint64_t EltSize = DL.getTypeAllocSize(CS->getOperand(Index)->getType());
340
341      if (ByteOffset < EltSize &&
342          !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr,
343                              BytesLeft, DL))
344        return false;
345
346      ++Index;
347
348      // Check to see if we read from the last struct element, if so we're done.
349      if (Index == CS->getType()->getNumElements())
350        return true;
351
352      // If we read all of the bytes we needed from this element we're done.
353      uint64_t NextEltOffset = SL->getElementOffset(Index);
354
355      if (BytesLeft <= NextEltOffset - CurEltOffset - ByteOffset)
356        return true;
357
358      // Move to the next element of the struct.
359      CurPtr += NextEltOffset - CurEltOffset - ByteOffset;
360      BytesLeft -= NextEltOffset - CurEltOffset - ByteOffset;
361      ByteOffset = 0;
362      CurEltOffset = NextEltOffset;
363    }
364    // not reached.
365  }
366
367  if (isa<ConstantArray>(C) || isa<ConstantVector>(C) ||
368      isa<ConstantDataSequential>(C)) {
369    Type *EltTy = C->getType()->getSequentialElementType();
370    uint64_t EltSize = DL.getTypeAllocSize(EltTy);
371    uint64_t Index = ByteOffset / EltSize;
372    uint64_t Offset = ByteOffset - Index * EltSize;
373    uint64_t NumElts;
374    if (auto *AT = dyn_cast<ArrayType>(C->getType()))
375      NumElts = AT->getNumElements();
376    else
377      NumElts = C->getType()->getVectorNumElements();
378
379    for (; Index != NumElts; ++Index) {
380      if (!ReadDataFromGlobal(C->getAggregateElement(Index), Offset, CurPtr,
381                              BytesLeft, DL))
382        return false;
383
384      uint64_t BytesWritten = EltSize - Offset;
385      assert(BytesWritten <= EltSize && "Not indexing into this element?");
386      if (BytesWritten >= BytesLeft)
387        return true;
388
389      Offset = 0;
390      BytesLeft -= BytesWritten;
391      CurPtr += BytesWritten;
392    }
393    return true;
394  }
395
396  if (auto *CE = dyn_cast<ConstantExpr>(C)) {
397    if (CE->getOpcode() == Instruction::IntToPtr &&
398        CE->getOperand(0)->getType() == DL.getIntPtrType(CE->getType())) {
399      return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr,
400                                BytesLeft, DL);
401    }
402  }
403
404  // Otherwise, unknown initializer type.
405  return false;
406}
407
408Constant *FoldReinterpretLoadFromConstPtr(Constant *C, Type *LoadTy,
409                                          const DataLayout &DL) {
410  auto *PTy = cast<PointerType>(C->getType());
411  auto *IntType = dyn_cast<IntegerType>(LoadTy);
412
413  // If this isn't an integer load we can't fold it directly.
414  if (!IntType) {
415    unsigned AS = PTy->getAddressSpace();
416
417    // If this is a float/double load, we can try folding it as an int32/64 load
418    // and then bitcast the result.  This can be useful for union cases.  Note
419    // that address spaces don't matter here since we're not going to result in
420    // an actual new load.
421    Type *MapTy;
422    if (LoadTy->isHalfTy())
423      MapTy = Type::getInt16Ty(C->getContext());
424    else if (LoadTy->isFloatTy())
425      MapTy = Type::getInt32Ty(C->getContext());
426    else if (LoadTy->isDoubleTy())
427      MapTy = Type::getInt64Ty(C->getContext());
428    else if (LoadTy->isVectorTy()) {
429      MapTy = PointerType::getIntNTy(C->getContext(),
430                                     DL.getTypeAllocSizeInBits(LoadTy));
431    } else
432      return nullptr;
433
434    C = FoldBitCast(C, MapTy->getPointerTo(AS), DL);
435    if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, MapTy, DL))
436      return FoldBitCast(Res, LoadTy, DL);
437    return nullptr;
438  }
439
440  unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
441  if (BytesLoaded > 32 || BytesLoaded == 0)
442    return nullptr;
443
444  GlobalValue *GVal;
445  APInt OffsetAI;
446  if (!IsConstantOffsetFromGlobal(C, GVal, OffsetAI, DL))
447    return nullptr;
448
449  auto *GV = dyn_cast<GlobalVariable>(GVal);
450  if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
451      !GV->getInitializer()->getType()->isSized())
452    return nullptr;
453
454  int64_t Offset = OffsetAI.getSExtValue();
455  int64_t InitializerSize = DL.getTypeAllocSize(GV->getInitializer()->getType());
456
457  // If we're not accessing anything in this constant, the result is undefined.
458  if (Offset + BytesLoaded <= 0)
459    return UndefValue::get(IntType);
460
461  // If we're not accessing anything in this constant, the result is undefined.
462  if (Offset >= InitializerSize)
463    return UndefValue::get(IntType);
464
465  unsigned char RawBytes[32] = {0};
466  unsigned char *CurPtr = RawBytes;
467  unsigned BytesLeft = BytesLoaded;
468
469  // If we're loading off the beginning of the global, some bytes may be valid.
470  if (Offset < 0) {
471    CurPtr += -Offset;
472    BytesLeft += Offset;
473    Offset = 0;
474  }
475
476  if (!ReadDataFromGlobal(GV->getInitializer(), Offset, CurPtr, BytesLeft, DL))
477    return nullptr;
478
479  APInt ResultVal = APInt(IntType->getBitWidth(), 0);
480  if (DL.isLittleEndian()) {
481    ResultVal = RawBytes[BytesLoaded - 1];
482    for (unsigned i = 1; i != BytesLoaded; ++i) {
483      ResultVal <<= 8;
484      ResultVal |= RawBytes[BytesLoaded - 1 - i];
485    }
486  } else {
487    ResultVal = RawBytes[0];
488    for (unsigned i = 1; i != BytesLoaded; ++i) {
489      ResultVal <<= 8;
490      ResultVal |= RawBytes[i];
491    }
492  }
493
494  return ConstantInt::get(IntType->getContext(), ResultVal);
495}
496
497Constant *ConstantFoldLoadThroughBitcast(ConstantExpr *CE, Type *DestTy,
498                                         const DataLayout &DL) {
499  auto *SrcPtr = CE->getOperand(0);
500  auto *SrcPtrTy = dyn_cast<PointerType>(SrcPtr->getType());
501  if (!SrcPtrTy)
502    return nullptr;
503  Type *SrcTy = SrcPtrTy->getPointerElementType();
504
505  Constant *C = ConstantFoldLoadFromConstPtr(SrcPtr, SrcTy, DL);
506  if (!C)
507    return nullptr;
508
509  do {
510    Type *SrcTy = C->getType();
511
512    // If the type sizes are the same and a cast is legal, just directly
513    // cast the constant.
514    if (DL.getTypeSizeInBits(DestTy) == DL.getTypeSizeInBits(SrcTy)) {
515      Instruction::CastOps Cast = Instruction::BitCast;
516      // If we are going from a pointer to int or vice versa, we spell the cast
517      // differently.
518      if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
519        Cast = Instruction::IntToPtr;
520      else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
521        Cast = Instruction::PtrToInt;
522
523      if (CastInst::castIsValid(Cast, C, DestTy))
524        return ConstantExpr::getCast(Cast, C, DestTy);
525    }
526
527    // If this isn't an aggregate type, there is nothing we can do to drill down
528    // and find a bitcastable constant.
529    if (!SrcTy->isAggregateType())
530      return nullptr;
531
532    // We're simulating a load through a pointer that was bitcast to point to
533    // a different type, so we can try to walk down through the initial
534    // elements of an aggregate to see if some part of th e aggregate is
535    // castable to implement the "load" semantic model.
536    C = C->getAggregateElement(0u);
537  } while (C);
538
539  return nullptr;
540}
541
542} // end anonymous namespace
543
544Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C, Type *Ty,
545                                             const DataLayout &DL) {
546  // First, try the easy cases:
547  if (auto *GV = dyn_cast<GlobalVariable>(C))
548    if (GV->isConstant() && GV->hasDefinitiveInitializer())
549      return GV->getInitializer();
550
551  if (auto *GA = dyn_cast<GlobalAlias>(C))
552    if (GA->getAliasee() && !GA->isInterposable())
553      return ConstantFoldLoadFromConstPtr(GA->getAliasee(), Ty, DL);
554
555  // If the loaded value isn't a constant expr, we can't handle it.
556  auto *CE = dyn_cast<ConstantExpr>(C);
557  if (!CE)
558    return nullptr;
559
560  if (CE->getOpcode() == Instruction::GetElementPtr) {
561    if (auto *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
562      if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
563        if (Constant *V =
564             ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
565          return V;
566      }
567    }
568  }
569
570  if (CE->getOpcode() == Instruction::BitCast)
571    if (Constant *LoadedC = ConstantFoldLoadThroughBitcast(CE, Ty, DL))
572      return LoadedC;
573
574  // Instead of loading constant c string, use corresponding integer value
575  // directly if string length is small enough.
576  StringRef Str;
577  if (getConstantStringInfo(CE, Str) && !Str.empty()) {
578    size_t StrLen = Str.size();
579    unsigned NumBits = Ty->getPrimitiveSizeInBits();
580    // Replace load with immediate integer if the result is an integer or fp
581    // value.
582    if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 &&
583        (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) {
584      APInt StrVal(NumBits, 0);
585      APInt SingleChar(NumBits, 0);
586      if (DL.isLittleEndian()) {
587        for (unsigned char C : reverse(Str.bytes())) {
588          SingleChar = static_cast<uint64_t>(C);
589          StrVal = (StrVal << 8) | SingleChar;
590        }
591      } else {
592        for (unsigned char C : Str.bytes()) {
593          SingleChar = static_cast<uint64_t>(C);
594          StrVal = (StrVal << 8) | SingleChar;
595        }
596        // Append NULL at the end.
597        SingleChar = 0;
598        StrVal = (StrVal << 8) | SingleChar;
599      }
600
601      Constant *Res = ConstantInt::get(CE->getContext(), StrVal);
602      if (Ty->isFloatingPointTy())
603        Res = ConstantExpr::getBitCast(Res, Ty);
604      return Res;
605    }
606  }
607
608  // If this load comes from anywhere in a constant global, and if the global
609  // is all undef or zero, we know what it loads.
610  if (auto *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(CE, DL))) {
611    if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
612      if (GV->getInitializer()->isNullValue())
613        return Constant::getNullValue(Ty);
614      if (isa<UndefValue>(GV->getInitializer()))
615        return UndefValue::get(Ty);
616    }
617  }
618
619  // Try hard to fold loads from bitcasted strange and non-type-safe things.
620  return FoldReinterpretLoadFromConstPtr(CE, Ty, DL);
621}
622
623namespace {
624
625Constant *ConstantFoldLoadInst(const LoadInst *LI, const DataLayout &DL) {
626  if (LI->isVolatile()) return nullptr;
627
628  if (auto *C = dyn_cast<Constant>(LI->getOperand(0)))
629    return ConstantFoldLoadFromConstPtr(C, LI->getType(), DL);
630
631  return nullptr;
632}
633
634/// One of Op0/Op1 is a constant expression.
635/// Attempt to symbolically evaluate the result of a binary operator merging
636/// these together.  If target data info is available, it is provided as DL,
637/// otherwise DL is null.
638Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0, Constant *Op1,
639                                    const DataLayout &DL) {
640  // SROA
641
642  // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
643  // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
644  // bits.
645
646  if (Opc == Instruction::And) {
647    unsigned BitWidth = DL.getTypeSizeInBits(Op0->getType()->getScalarType());
648    APInt KnownZero0(BitWidth, 0), KnownOne0(BitWidth, 0);
649    APInt KnownZero1(BitWidth, 0), KnownOne1(BitWidth, 0);
650    computeKnownBits(Op0, KnownZero0, KnownOne0, DL);
651    computeKnownBits(Op1, KnownZero1, KnownOne1, DL);
652    if ((KnownOne1 | KnownZero0).isAllOnesValue()) {
653      // All the bits of Op0 that the 'and' could be masking are already zero.
654      return Op0;
655    }
656    if ((KnownOne0 | KnownZero1).isAllOnesValue()) {
657      // All the bits of Op1 that the 'and' could be masking are already zero.
658      return Op1;
659    }
660
661    APInt KnownZero = KnownZero0 | KnownZero1;
662    APInt KnownOne = KnownOne0 & KnownOne1;
663    if ((KnownZero | KnownOne).isAllOnesValue()) {
664      return ConstantInt::get(Op0->getType(), KnownOne);
665    }
666  }
667
668  // If the constant expr is something like &A[123] - &A[4].f, fold this into a
669  // constant.  This happens frequently when iterating over a global array.
670  if (Opc == Instruction::Sub) {
671    GlobalValue *GV1, *GV2;
672    APInt Offs1, Offs2;
673
674    if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, DL))
675      if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, DL) && GV1 == GV2) {
676        unsigned OpSize = DL.getTypeSizeInBits(Op0->getType());
677
678        // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
679        // PtrToInt may change the bitwidth so we have convert to the right size
680        // first.
681        return ConstantInt::get(Op0->getType(), Offs1.zextOrTrunc(OpSize) -
682                                                Offs2.zextOrTrunc(OpSize));
683      }
684  }
685
686  return nullptr;
687}
688
689/// If array indices are not pointer-sized integers, explicitly cast them so
690/// that they aren't implicitly casted by the getelementptr.
691Constant *CastGEPIndices(Type *SrcElemTy, ArrayRef<Constant *> Ops,
692                         Type *ResultTy, const DataLayout &DL,
693                         const TargetLibraryInfo *TLI) {
694  Type *IntPtrTy = DL.getIntPtrType(ResultTy);
695
696  bool Any = false;
697  SmallVector<Constant*, 32> NewIdxs;
698  for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
699    if ((i == 1 ||
700         !isa<StructType>(GetElementPtrInst::getIndexedType(SrcElemTy,
701             Ops.slice(1, i - 1)))) &&
702        Ops[i]->getType() != IntPtrTy) {
703      Any = true;
704      NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i],
705                                                                      true,
706                                                                      IntPtrTy,
707                                                                      true),
708                                              Ops[i], IntPtrTy));
709    } else
710      NewIdxs.push_back(Ops[i]);
711  }
712
713  if (!Any)
714    return nullptr;
715
716  Constant *C = ConstantExpr::getGetElementPtr(SrcElemTy, Ops[0], NewIdxs);
717  if (auto *CE = dyn_cast<ConstantExpr>(C)) {
718    if (Constant *Folded = ConstantFoldConstantExpression(CE, DL, TLI))
719      C = Folded;
720  }
721
722  return C;
723}
724
725/// Strip the pointer casts, but preserve the address space information.
726Constant* StripPtrCastKeepAS(Constant* Ptr, Type *&ElemTy) {
727  assert(Ptr->getType()->isPointerTy() && "Not a pointer type");
728  auto *OldPtrTy = cast<PointerType>(Ptr->getType());
729  Ptr = Ptr->stripPointerCasts();
730  auto *NewPtrTy = cast<PointerType>(Ptr->getType());
731
732  ElemTy = NewPtrTy->getPointerElementType();
733
734  // Preserve the address space number of the pointer.
735  if (NewPtrTy->getAddressSpace() != OldPtrTy->getAddressSpace()) {
736    NewPtrTy = ElemTy->getPointerTo(OldPtrTy->getAddressSpace());
737    Ptr = ConstantExpr::getPointerCast(Ptr, NewPtrTy);
738  }
739  return Ptr;
740}
741
742/// If we can symbolically evaluate the GEP constant expression, do so.
743Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
744                                  ArrayRef<Constant *> Ops,
745                                  const DataLayout &DL,
746                                  const TargetLibraryInfo *TLI) {
747  Type *SrcElemTy = GEP->getSourceElementType();
748  Type *ResElemTy = GEP->getResultElementType();
749  Type *ResTy = GEP->getType();
750  if (!SrcElemTy->isSized())
751    return nullptr;
752
753  if (Constant *C = CastGEPIndices(SrcElemTy, Ops, ResTy, DL, TLI))
754    return C;
755
756  Constant *Ptr = Ops[0];
757  if (!Ptr->getType()->isPointerTy())
758    return nullptr;
759
760  Type *IntPtrTy = DL.getIntPtrType(Ptr->getType());
761
762  // If this is a constant expr gep that is effectively computing an
763  // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
764  for (unsigned i = 1, e = Ops.size(); i != e; ++i)
765    if (!isa<ConstantInt>(Ops[i])) {
766
767      // If this is "gep i8* Ptr, (sub 0, V)", fold this as:
768      // "inttoptr (sub (ptrtoint Ptr), V)"
769      if (Ops.size() == 2 && ResElemTy->isIntegerTy(8)) {
770        auto *CE = dyn_cast<ConstantExpr>(Ops[1]);
771        assert((!CE || CE->getType() == IntPtrTy) &&
772               "CastGEPIndices didn't canonicalize index types!");
773        if (CE && CE->getOpcode() == Instruction::Sub &&
774            CE->getOperand(0)->isNullValue()) {
775          Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType());
776          Res = ConstantExpr::getSub(Res, CE->getOperand(1));
777          Res = ConstantExpr::getIntToPtr(Res, ResTy);
778          if (auto *ResCE = dyn_cast<ConstantExpr>(Res))
779            Res = ConstantFoldConstantExpression(ResCE, DL, TLI);
780          return Res;
781        }
782      }
783      return nullptr;
784    }
785
786  unsigned BitWidth = DL.getTypeSizeInBits(IntPtrTy);
787  APInt Offset =
788      APInt(BitWidth,
789            DL.getIndexedOffsetInType(
790                SrcElemTy,
791                makeArrayRef((Value * const *)Ops.data() + 1, Ops.size() - 1)));
792  Ptr = StripPtrCastKeepAS(Ptr, SrcElemTy);
793
794  // If this is a GEP of a GEP, fold it all into a single GEP.
795  while (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
796    SmallVector<Value *, 4> NestedOps(GEP->op_begin() + 1, GEP->op_end());
797
798    // Do not try the incorporate the sub-GEP if some index is not a number.
799    bool AllConstantInt = true;
800    for (Value *NestedOp : NestedOps)
801      if (!isa<ConstantInt>(NestedOp)) {
802        AllConstantInt = false;
803        break;
804      }
805    if (!AllConstantInt)
806      break;
807
808    Ptr = cast<Constant>(GEP->getOperand(0));
809    SrcElemTy = GEP->getSourceElementType();
810    Offset += APInt(BitWidth, DL.getIndexedOffsetInType(SrcElemTy, NestedOps));
811    Ptr = StripPtrCastKeepAS(Ptr, SrcElemTy);
812  }
813
814  // If the base value for this address is a literal integer value, fold the
815  // getelementptr to the resulting integer value casted to the pointer type.
816  APInt BasePtr(BitWidth, 0);
817  if (auto *CE = dyn_cast<ConstantExpr>(Ptr)) {
818    if (CE->getOpcode() == Instruction::IntToPtr) {
819      if (auto *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
820        BasePtr = Base->getValue().zextOrTrunc(BitWidth);
821    }
822  }
823
824  if (Ptr->isNullValue() || BasePtr != 0) {
825    Constant *C = ConstantInt::get(Ptr->getContext(), Offset + BasePtr);
826    return ConstantExpr::getIntToPtr(C, ResTy);
827  }
828
829  // Otherwise form a regular getelementptr. Recompute the indices so that
830  // we eliminate over-indexing of the notional static type array bounds.
831  // This makes it easy to determine if the getelementptr is "inbounds".
832  // Also, this helps GlobalOpt do SROA on GlobalVariables.
833  Type *Ty = Ptr->getType();
834  assert(Ty->isPointerTy() && "Forming regular GEP of non-pointer type");
835  SmallVector<Constant *, 32> NewIdxs;
836
837  do {
838    if (!Ty->isStructTy()) {
839      if (Ty->isPointerTy()) {
840        // The only pointer indexing we'll do is on the first index of the GEP.
841        if (!NewIdxs.empty())
842          break;
843
844        Ty = SrcElemTy;
845
846        // Only handle pointers to sized types, not pointers to functions.
847        if (!Ty->isSized())
848          return nullptr;
849      } else if (auto *ATy = dyn_cast<SequentialType>(Ty)) {
850        Ty = ATy->getElementType();
851      } else {
852        // We've reached some non-indexable type.
853        break;
854      }
855
856      // Determine which element of the array the offset points into.
857      APInt ElemSize(BitWidth, DL.getTypeAllocSize(Ty));
858      if (ElemSize == 0) {
859        // The element size is 0. This may be [0 x Ty]*, so just use a zero
860        // index for this level and proceed to the next level to see if it can
861        // accommodate the offset.
862        NewIdxs.push_back(ConstantInt::get(IntPtrTy, 0));
863      } else {
864        // The element size is non-zero divide the offset by the element
865        // size (rounding down), to compute the index at this level.
866        bool Overflow;
867        APInt NewIdx = Offset.sdiv_ov(ElemSize, Overflow);
868        if (Overflow)
869          break;
870        Offset -= NewIdx * ElemSize;
871        NewIdxs.push_back(ConstantInt::get(IntPtrTy, NewIdx));
872      }
873    } else {
874      auto *STy = cast<StructType>(Ty);
875      // If we end up with an offset that isn't valid for this struct type, we
876      // can't re-form this GEP in a regular form, so bail out. The pointer
877      // operand likely went through casts that are necessary to make the GEP
878      // sensible.
879      const StructLayout &SL = *DL.getStructLayout(STy);
880      if (Offset.isNegative() || Offset.uge(SL.getSizeInBytes()))
881        break;
882
883      // Determine which field of the struct the offset points into. The
884      // getZExtValue is fine as we've already ensured that the offset is
885      // within the range representable by the StructLayout API.
886      unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue());
887      NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
888                                         ElIdx));
889      Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
890      Ty = STy->getTypeAtIndex(ElIdx);
891    }
892  } while (Ty != ResElemTy);
893
894  // If we haven't used up the entire offset by descending the static
895  // type, then the offset is pointing into the middle of an indivisible
896  // member, so we can't simplify it.
897  if (Offset != 0)
898    return nullptr;
899
900  // Create a GEP.
901  Constant *C = ConstantExpr::getGetElementPtr(SrcElemTy, Ptr, NewIdxs);
902  assert(C->getType()->getPointerElementType() == Ty &&
903         "Computed GetElementPtr has unexpected type!");
904
905  // If we ended up indexing a member with a type that doesn't match
906  // the type of what the original indices indexed, add a cast.
907  if (Ty != ResElemTy)
908    C = FoldBitCast(C, ResTy, DL);
909
910  return C;
911}
912
913/// Attempt to constant fold an instruction with the
914/// specified opcode and operands.  If successful, the constant result is
915/// returned, if not, null is returned.  Note that this function can fail when
916/// attempting to fold instructions like loads and stores, which have no
917/// constant expression form.
918///
919/// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
920/// information, due to only being passed an opcode and operands. Constant
921/// folding using this function strips this information.
922///
923Constant *ConstantFoldInstOperandsImpl(const Value *InstOrCE, Type *DestTy,
924                                       unsigned Opcode,
925                                       ArrayRef<Constant *> Ops,
926                                       const DataLayout &DL,
927                                       const TargetLibraryInfo *TLI) {
928  // Handle easy binops first.
929  if (Instruction::isBinaryOp(Opcode))
930    return ConstantFoldBinaryOpOperands(Opcode, Ops[0], Ops[1], DL);
931
932  if (Instruction::isCast(Opcode))
933    return ConstantFoldCastOperand(Opcode, Ops[0], DestTy, DL);
934
935  if (auto *GEP = dyn_cast<GEPOperator>(InstOrCE)) {
936    if (Constant *C = SymbolicallyEvaluateGEP(GEP, Ops, DL, TLI))
937      return C;
938
939    return ConstantExpr::getGetElementPtr(GEP->getSourceElementType(),
940                                          Ops[0], Ops.slice(1));
941  }
942
943  switch (Opcode) {
944  default: return nullptr;
945  case Instruction::ICmp:
946  case Instruction::FCmp: llvm_unreachable("Invalid for compares");
947  case Instruction::Call:
948    if (auto *F = dyn_cast<Function>(Ops.back()))
949      if (canConstantFoldCallTo(F))
950        return ConstantFoldCall(F, Ops.slice(0, Ops.size() - 1), TLI);
951    return nullptr;
952  case Instruction::Select:
953    return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
954  case Instruction::ExtractElement:
955    return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
956  case Instruction::InsertElement:
957    return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
958  case Instruction::ShuffleVector:
959    return ConstantExpr::getShuffleVector(Ops[0], Ops[1], Ops[2]);
960  }
961}
962
963} // end anonymous namespace
964
965//===----------------------------------------------------------------------===//
966// Constant Folding public APIs
967//===----------------------------------------------------------------------===//
968
969Constant *llvm::ConstantFoldInstruction(Instruction *I, const DataLayout &DL,
970                                        const TargetLibraryInfo *TLI) {
971  // Handle PHI nodes quickly here...
972  if (auto *PN = dyn_cast<PHINode>(I)) {
973    Constant *CommonValue = nullptr;
974
975    for (Value *Incoming : PN->incoming_values()) {
976      // If the incoming value is undef then skip it.  Note that while we could
977      // skip the value if it is equal to the phi node itself we choose not to
978      // because that would break the rule that constant folding only applies if
979      // all operands are constants.
980      if (isa<UndefValue>(Incoming))
981        continue;
982      // If the incoming value is not a constant, then give up.
983      auto *C = dyn_cast<Constant>(Incoming);
984      if (!C)
985        return nullptr;
986      // Fold the PHI's operands.
987      if (auto *NewC = dyn_cast<ConstantExpr>(C))
988        C = ConstantFoldConstantExpression(NewC, DL, TLI);
989      // If the incoming value is a different constant to
990      // the one we saw previously, then give up.
991      if (CommonValue && C != CommonValue)
992        return nullptr;
993      CommonValue = C;
994    }
995
996
997    // If we reach here, all incoming values are the same constant or undef.
998    return CommonValue ? CommonValue : UndefValue::get(PN->getType());
999  }
1000
1001  // Scan the operand list, checking to see if they are all constants, if so,
1002  // hand off to ConstantFoldInstOperandsImpl.
1003  if (!all_of(I->operands(), [](Use &U) { return isa<Constant>(U); }))
1004    return nullptr;
1005
1006  SmallVector<Constant *, 8> Ops;
1007  for (const Use &OpU : I->operands()) {
1008    auto *Op = cast<Constant>(&OpU);
1009    // Fold the Instruction's operands.
1010    if (auto *NewCE = dyn_cast<ConstantExpr>(Op))
1011      Op = ConstantFoldConstantExpression(NewCE, DL, TLI);
1012
1013    Ops.push_back(Op);
1014  }
1015
1016  if (const auto *CI = dyn_cast<CmpInst>(I))
1017    return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
1018                                           DL, TLI);
1019
1020  if (const auto *LI = dyn_cast<LoadInst>(I))
1021    return ConstantFoldLoadInst(LI, DL);
1022
1023  if (auto *IVI = dyn_cast<InsertValueInst>(I)) {
1024    return ConstantExpr::getInsertValue(
1025                                cast<Constant>(IVI->getAggregateOperand()),
1026                                cast<Constant>(IVI->getInsertedValueOperand()),
1027                                IVI->getIndices());
1028  }
1029
1030  if (auto *EVI = dyn_cast<ExtractValueInst>(I)) {
1031    return ConstantExpr::getExtractValue(
1032                                    cast<Constant>(EVI->getAggregateOperand()),
1033                                    EVI->getIndices());
1034  }
1035
1036  return ConstantFoldInstOperands(I, Ops, DL, TLI);
1037}
1038
1039namespace {
1040
1041Constant *
1042ConstantFoldConstantExpressionImpl(const ConstantExpr *CE, const DataLayout &DL,
1043                                   const TargetLibraryInfo *TLI,
1044                                   SmallPtrSetImpl<ConstantExpr *> &FoldedOps) {
1045  SmallVector<Constant *, 8> Ops;
1046  for (const Use &NewU : CE->operands()) {
1047    auto *NewC = cast<Constant>(&NewU);
1048    // Recursively fold the ConstantExpr's operands. If we have already folded
1049    // a ConstantExpr, we don't have to process it again.
1050    if (auto *NewCE = dyn_cast<ConstantExpr>(NewC)) {
1051      if (FoldedOps.insert(NewCE).second)
1052        NewC = ConstantFoldConstantExpressionImpl(NewCE, DL, TLI, FoldedOps);
1053    }
1054    Ops.push_back(NewC);
1055  }
1056
1057  if (CE->isCompare())
1058    return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
1059                                           DL, TLI);
1060
1061  return ConstantFoldInstOperandsImpl(CE, CE->getType(), CE->getOpcode(), Ops,
1062                                      DL, TLI);
1063}
1064
1065} // end anonymous namespace
1066
1067Constant *llvm::ConstantFoldConstantExpression(const ConstantExpr *CE,
1068                                               const DataLayout &DL,
1069                                               const TargetLibraryInfo *TLI) {
1070  SmallPtrSet<ConstantExpr *, 4> FoldedOps;
1071  return ConstantFoldConstantExpressionImpl(CE, DL, TLI, FoldedOps);
1072}
1073
1074Constant *llvm::ConstantFoldInstOperands(Instruction *I,
1075                                         ArrayRef<Constant *> Ops,
1076                                         const DataLayout &DL,
1077                                         const TargetLibraryInfo *TLI) {
1078  return ConstantFoldInstOperandsImpl(I, I->getType(), I->getOpcode(), Ops, DL,
1079                                      TLI);
1080}
1081
1082Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, Type *DestTy,
1083                                         ArrayRef<Constant *> Ops,
1084                                         const DataLayout &DL,
1085                                         const TargetLibraryInfo *TLI) {
1086  assert(Opcode != Instruction::GetElementPtr && "Invalid for GEPs");
1087  return ConstantFoldInstOperandsImpl(nullptr, DestTy, Opcode, Ops, DL, TLI);
1088}
1089
1090Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
1091                                                Constant *Ops0, Constant *Ops1,
1092                                                const DataLayout &DL,
1093                                                const TargetLibraryInfo *TLI) {
1094  // fold: icmp (inttoptr x), null         -> icmp x, 0
1095  // fold: icmp (ptrtoint x), 0            -> icmp x, null
1096  // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
1097  // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
1098  //
1099  // FIXME: The following comment is out of data and the DataLayout is here now.
1100  // ConstantExpr::getCompare cannot do this, because it doesn't have DL
1101  // around to know if bit truncation is happening.
1102  if (auto *CE0 = dyn_cast<ConstantExpr>(Ops0)) {
1103    if (Ops1->isNullValue()) {
1104      if (CE0->getOpcode() == Instruction::IntToPtr) {
1105        Type *IntPtrTy = DL.getIntPtrType(CE0->getType());
1106        // Convert the integer value to the right size to ensure we get the
1107        // proper extension or truncation.
1108        Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
1109                                                   IntPtrTy, false);
1110        Constant *Null = Constant::getNullValue(C->getType());
1111        return ConstantFoldCompareInstOperands(Predicate, C, Null, DL, TLI);
1112      }
1113
1114      // Only do this transformation if the int is intptrty in size, otherwise
1115      // there is a truncation or extension that we aren't modeling.
1116      if (CE0->getOpcode() == Instruction::PtrToInt) {
1117        Type *IntPtrTy = DL.getIntPtrType(CE0->getOperand(0)->getType());
1118        if (CE0->getType() == IntPtrTy) {
1119          Constant *C = CE0->getOperand(0);
1120          Constant *Null = Constant::getNullValue(C->getType());
1121          return ConstantFoldCompareInstOperands(Predicate, C, Null, DL, TLI);
1122        }
1123      }
1124    }
1125
1126    if (auto *CE1 = dyn_cast<ConstantExpr>(Ops1)) {
1127      if (CE0->getOpcode() == CE1->getOpcode()) {
1128        if (CE0->getOpcode() == Instruction::IntToPtr) {
1129          Type *IntPtrTy = DL.getIntPtrType(CE0->getType());
1130
1131          // Convert the integer value to the right size to ensure we get the
1132          // proper extension or truncation.
1133          Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
1134                                                      IntPtrTy, false);
1135          Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
1136                                                      IntPtrTy, false);
1137          return ConstantFoldCompareInstOperands(Predicate, C0, C1, DL, TLI);
1138        }
1139
1140        // Only do this transformation if the int is intptrty in size, otherwise
1141        // there is a truncation or extension that we aren't modeling.
1142        if (CE0->getOpcode() == Instruction::PtrToInt) {
1143          Type *IntPtrTy = DL.getIntPtrType(CE0->getOperand(0)->getType());
1144          if (CE0->getType() == IntPtrTy &&
1145              CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType()) {
1146            return ConstantFoldCompareInstOperands(
1147                Predicate, CE0->getOperand(0), CE1->getOperand(0), DL, TLI);
1148          }
1149        }
1150      }
1151    }
1152
1153    // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
1154    // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
1155    if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
1156        CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
1157      Constant *LHS = ConstantFoldCompareInstOperands(
1158          Predicate, CE0->getOperand(0), Ops1, DL, TLI);
1159      Constant *RHS = ConstantFoldCompareInstOperands(
1160          Predicate, CE0->getOperand(1), Ops1, DL, TLI);
1161      unsigned OpC =
1162        Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
1163      return ConstantFoldBinaryOpOperands(OpC, LHS, RHS, DL);
1164    }
1165  }
1166
1167  return ConstantExpr::getCompare(Predicate, Ops0, Ops1);
1168}
1169
1170Constant *llvm::ConstantFoldBinaryOpOperands(unsigned Opcode, Constant *LHS,
1171                                             Constant *RHS,
1172                                             const DataLayout &DL) {
1173  assert(Instruction::isBinaryOp(Opcode));
1174  if (isa<ConstantExpr>(LHS) || isa<ConstantExpr>(RHS))
1175    if (Constant *C = SymbolicallyEvaluateBinop(Opcode, LHS, RHS, DL))
1176      return C;
1177
1178  return ConstantExpr::get(Opcode, LHS, RHS);
1179}
1180
1181Constant *llvm::ConstantFoldCastOperand(unsigned Opcode, Constant *C,
1182                                        Type *DestTy, const DataLayout &DL) {
1183  assert(Instruction::isCast(Opcode));
1184  switch (Opcode) {
1185  default:
1186    llvm_unreachable("Missing case");
1187  case Instruction::PtrToInt:
1188    // If the input is a inttoptr, eliminate the pair.  This requires knowing
1189    // the width of a pointer, so it can't be done in ConstantExpr::getCast.
1190    if (auto *CE = dyn_cast<ConstantExpr>(C)) {
1191      if (CE->getOpcode() == Instruction::IntToPtr) {
1192        Constant *Input = CE->getOperand(0);
1193        unsigned InWidth = Input->getType()->getScalarSizeInBits();
1194        unsigned PtrWidth = DL.getPointerTypeSizeInBits(CE->getType());
1195        if (PtrWidth < InWidth) {
1196          Constant *Mask =
1197            ConstantInt::get(CE->getContext(),
1198                             APInt::getLowBitsSet(InWidth, PtrWidth));
1199          Input = ConstantExpr::getAnd(Input, Mask);
1200        }
1201        // Do a zext or trunc to get to the dest size.
1202        return ConstantExpr::getIntegerCast(Input, DestTy, false);
1203      }
1204    }
1205    return ConstantExpr::getCast(Opcode, C, DestTy);
1206  case Instruction::IntToPtr:
1207    // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
1208    // the int size is >= the ptr size and the address spaces are the same.
1209    // This requires knowing the width of a pointer, so it can't be done in
1210    // ConstantExpr::getCast.
1211    if (auto *CE = dyn_cast<ConstantExpr>(C)) {
1212      if (CE->getOpcode() == Instruction::PtrToInt) {
1213        Constant *SrcPtr = CE->getOperand(0);
1214        unsigned SrcPtrSize = DL.getPointerTypeSizeInBits(SrcPtr->getType());
1215        unsigned MidIntSize = CE->getType()->getScalarSizeInBits();
1216
1217        if (MidIntSize >= SrcPtrSize) {
1218          unsigned SrcAS = SrcPtr->getType()->getPointerAddressSpace();
1219          if (SrcAS == DestTy->getPointerAddressSpace())
1220            return FoldBitCast(CE->getOperand(0), DestTy, DL);
1221        }
1222      }
1223    }
1224
1225    return ConstantExpr::getCast(Opcode, C, DestTy);
1226  case Instruction::Trunc:
1227  case Instruction::ZExt:
1228  case Instruction::SExt:
1229  case Instruction::FPTrunc:
1230  case Instruction::FPExt:
1231  case Instruction::UIToFP:
1232  case Instruction::SIToFP:
1233  case Instruction::FPToUI:
1234  case Instruction::FPToSI:
1235  case Instruction::AddrSpaceCast:
1236      return ConstantExpr::getCast(Opcode, C, DestTy);
1237  case Instruction::BitCast:
1238    return FoldBitCast(C, DestTy, DL);
1239  }
1240}
1241
1242Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
1243                                                       ConstantExpr *CE) {
1244  if (!CE->getOperand(1)->isNullValue())
1245    return nullptr;  // Do not allow stepping over the value!
1246
1247  // Loop over all of the operands, tracking down which value we are
1248  // addressing.
1249  for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i) {
1250    C = C->getAggregateElement(CE->getOperand(i));
1251    if (!C)
1252      return nullptr;
1253  }
1254  return C;
1255}
1256
1257Constant *
1258llvm::ConstantFoldLoadThroughGEPIndices(Constant *C,
1259                                        ArrayRef<Constant *> Indices) {
1260  // Loop over all of the operands, tracking down which value we are
1261  // addressing.
1262  for (Constant *Index : Indices) {
1263    C = C->getAggregateElement(Index);
1264    if (!C)
1265      return nullptr;
1266  }
1267  return C;
1268}
1269
1270//===----------------------------------------------------------------------===//
1271//  Constant Folding for Calls
1272//
1273
1274bool llvm::canConstantFoldCallTo(const Function *F) {
1275  switch (F->getIntrinsicID()) {
1276  case Intrinsic::fabs:
1277  case Intrinsic::minnum:
1278  case Intrinsic::maxnum:
1279  case Intrinsic::log:
1280  case Intrinsic::log2:
1281  case Intrinsic::log10:
1282  case Intrinsic::exp:
1283  case Intrinsic::exp2:
1284  case Intrinsic::floor:
1285  case Intrinsic::ceil:
1286  case Intrinsic::sqrt:
1287  case Intrinsic::sin:
1288  case Intrinsic::cos:
1289  case Intrinsic::trunc:
1290  case Intrinsic::rint:
1291  case Intrinsic::nearbyint:
1292  case Intrinsic::pow:
1293  case Intrinsic::powi:
1294  case Intrinsic::bswap:
1295  case Intrinsic::ctpop:
1296  case Intrinsic::ctlz:
1297  case Intrinsic::cttz:
1298  case Intrinsic::fma:
1299  case Intrinsic::fmuladd:
1300  case Intrinsic::copysign:
1301  case Intrinsic::round:
1302  case Intrinsic::masked_load:
1303  case Intrinsic::sadd_with_overflow:
1304  case Intrinsic::uadd_with_overflow:
1305  case Intrinsic::ssub_with_overflow:
1306  case Intrinsic::usub_with_overflow:
1307  case Intrinsic::smul_with_overflow:
1308  case Intrinsic::umul_with_overflow:
1309  case Intrinsic::convert_from_fp16:
1310  case Intrinsic::convert_to_fp16:
1311  case Intrinsic::bitreverse:
1312  case Intrinsic::x86_sse_cvtss2si:
1313  case Intrinsic::x86_sse_cvtss2si64:
1314  case Intrinsic::x86_sse_cvttss2si:
1315  case Intrinsic::x86_sse_cvttss2si64:
1316  case Intrinsic::x86_sse2_cvtsd2si:
1317  case Intrinsic::x86_sse2_cvtsd2si64:
1318  case Intrinsic::x86_sse2_cvttsd2si:
1319  case Intrinsic::x86_sse2_cvttsd2si64:
1320    return true;
1321  default:
1322    return false;
1323  case 0: break;
1324  }
1325
1326  if (!F->hasName())
1327    return false;
1328  StringRef Name = F->getName();
1329
1330  // In these cases, the check of the length is required.  We don't want to
1331  // return true for a name like "cos\0blah" which strcmp would return equal to
1332  // "cos", but has length 8.
1333  switch (Name[0]) {
1334  default:
1335    return false;
1336  case 'a':
1337    return Name == "acos" || Name == "asin" || Name == "atan" ||
1338           Name == "atan2" || Name == "acosf" || Name == "asinf" ||
1339           Name == "atanf" || Name == "atan2f";
1340  case 'c':
1341    return Name == "ceil" || Name == "cos" || Name == "cosh" ||
1342           Name == "ceilf" || Name == "cosf" || Name == "coshf";
1343  case 'e':
1344    return Name == "exp" || Name == "exp2" || Name == "expf" || Name == "exp2f";
1345  case 'f':
1346    return Name == "fabs" || Name == "floor" || Name == "fmod" ||
1347           Name == "fabsf" || Name == "floorf" || Name == "fmodf";
1348  case 'l':
1349    return Name == "log" || Name == "log10" || Name == "logf" ||
1350           Name == "log10f";
1351  case 'p':
1352    return Name == "pow" || Name == "powf";
1353  case 's':
1354    return Name == "sin" || Name == "sinh" || Name == "sqrt" ||
1355           Name == "sinf" || Name == "sinhf" || Name == "sqrtf";
1356  case 't':
1357    return Name == "tan" || Name == "tanh" || Name == "tanf" || Name == "tanhf";
1358  }
1359}
1360
1361namespace {
1362
1363Constant *GetConstantFoldFPValue(double V, Type *Ty) {
1364  if (Ty->isHalfTy()) {
1365    APFloat APF(V);
1366    bool unused;
1367    APF.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &unused);
1368    return ConstantFP::get(Ty->getContext(), APF);
1369  }
1370  if (Ty->isFloatTy())
1371    return ConstantFP::get(Ty->getContext(), APFloat((float)V));
1372  if (Ty->isDoubleTy())
1373    return ConstantFP::get(Ty->getContext(), APFloat(V));
1374  llvm_unreachable("Can only constant fold half/float/double");
1375}
1376
1377/// Clear the floating-point exception state.
1378inline void llvm_fenv_clearexcept() {
1379#if defined(HAVE_FENV_H) && HAVE_DECL_FE_ALL_EXCEPT
1380  feclearexcept(FE_ALL_EXCEPT);
1381#endif
1382  errno = 0;
1383}
1384
1385/// Test if a floating-point exception was raised.
1386inline bool llvm_fenv_testexcept() {
1387  int errno_val = errno;
1388  if (errno_val == ERANGE || errno_val == EDOM)
1389    return true;
1390#if defined(HAVE_FENV_H) && HAVE_DECL_FE_ALL_EXCEPT && HAVE_DECL_FE_INEXACT
1391  if (fetestexcept(FE_ALL_EXCEPT & ~FE_INEXACT))
1392    return true;
1393#endif
1394  return false;
1395}
1396
1397Constant *ConstantFoldFP(double (*NativeFP)(double), double V, Type *Ty) {
1398  llvm_fenv_clearexcept();
1399  V = NativeFP(V);
1400  if (llvm_fenv_testexcept()) {
1401    llvm_fenv_clearexcept();
1402    return nullptr;
1403  }
1404
1405  return GetConstantFoldFPValue(V, Ty);
1406}
1407
1408Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double), double V,
1409                               double W, Type *Ty) {
1410  llvm_fenv_clearexcept();
1411  V = NativeFP(V, W);
1412  if (llvm_fenv_testexcept()) {
1413    llvm_fenv_clearexcept();
1414    return nullptr;
1415  }
1416
1417  return GetConstantFoldFPValue(V, Ty);
1418}
1419
1420/// Attempt to fold an SSE floating point to integer conversion of a constant
1421/// floating point. If roundTowardZero is false, the default IEEE rounding is
1422/// used (toward nearest, ties to even). This matches the behavior of the
1423/// non-truncating SSE instructions in the default rounding mode. The desired
1424/// integer type Ty is used to select how many bits are available for the
1425/// result. Returns null if the conversion cannot be performed, otherwise
1426/// returns the Constant value resulting from the conversion.
1427Constant *ConstantFoldConvertToInt(const APFloat &Val, bool roundTowardZero,
1428                                   Type *Ty) {
1429  // All of these conversion intrinsics form an integer of at most 64bits.
1430  unsigned ResultWidth = Ty->getIntegerBitWidth();
1431  assert(ResultWidth <= 64 &&
1432         "Can only constant fold conversions to 64 and 32 bit ints");
1433
1434  uint64_t UIntVal;
1435  bool isExact = false;
1436  APFloat::roundingMode mode = roundTowardZero? APFloat::rmTowardZero
1437                                              : APFloat::rmNearestTiesToEven;
1438  APFloat::opStatus status = Val.convertToInteger(&UIntVal, ResultWidth,
1439                                                  /*isSigned=*/true, mode,
1440                                                  &isExact);
1441  if (status != APFloat::opOK && status != APFloat::opInexact)
1442    return nullptr;
1443  return ConstantInt::get(Ty, UIntVal, /*isSigned=*/true);
1444}
1445
1446double getValueAsDouble(ConstantFP *Op) {
1447  Type *Ty = Op->getType();
1448
1449  if (Ty->isFloatTy())
1450    return Op->getValueAPF().convertToFloat();
1451
1452  if (Ty->isDoubleTy())
1453    return Op->getValueAPF().convertToDouble();
1454
1455  bool unused;
1456  APFloat APF = Op->getValueAPF();
1457  APF.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &unused);
1458  return APF.convertToDouble();
1459}
1460
1461Constant *ConstantFoldScalarCall(StringRef Name, unsigned IntrinsicID, Type *Ty,
1462                                 ArrayRef<Constant *> Operands,
1463                                 const TargetLibraryInfo *TLI) {
1464  if (Operands.size() == 1) {
1465    if (isa<UndefValue>(Operands[0])) {
1466      // cosine(arg) is between -1 and 1. cosine(invalid arg) is NaN
1467      if (IntrinsicID == Intrinsic::cos)
1468        return Constant::getNullValue(Ty);
1469    }
1470    if (auto *Op = dyn_cast<ConstantFP>(Operands[0])) {
1471      if (IntrinsicID == Intrinsic::convert_to_fp16) {
1472        APFloat Val(Op->getValueAPF());
1473
1474        bool lost = false;
1475        Val.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven, &lost);
1476
1477        return ConstantInt::get(Ty->getContext(), Val.bitcastToAPInt());
1478      }
1479
1480      if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
1481        return nullptr;
1482
1483      if (IntrinsicID == Intrinsic::round) {
1484        APFloat V = Op->getValueAPF();
1485        V.roundToIntegral(APFloat::rmNearestTiesToAway);
1486        return ConstantFP::get(Ty->getContext(), V);
1487      }
1488
1489      if (IntrinsicID == Intrinsic::floor) {
1490        APFloat V = Op->getValueAPF();
1491        V.roundToIntegral(APFloat::rmTowardNegative);
1492        return ConstantFP::get(Ty->getContext(), V);
1493      }
1494
1495      if (IntrinsicID == Intrinsic::ceil) {
1496        APFloat V = Op->getValueAPF();
1497        V.roundToIntegral(APFloat::rmTowardPositive);
1498        return ConstantFP::get(Ty->getContext(), V);
1499      }
1500
1501      if (IntrinsicID == Intrinsic::trunc) {
1502        APFloat V = Op->getValueAPF();
1503        V.roundToIntegral(APFloat::rmTowardZero);
1504        return ConstantFP::get(Ty->getContext(), V);
1505      }
1506
1507      if (IntrinsicID == Intrinsic::rint) {
1508        APFloat V = Op->getValueAPF();
1509        V.roundToIntegral(APFloat::rmNearestTiesToEven);
1510        return ConstantFP::get(Ty->getContext(), V);
1511      }
1512
1513      if (IntrinsicID == Intrinsic::nearbyint) {
1514        APFloat V = Op->getValueAPF();
1515        V.roundToIntegral(APFloat::rmNearestTiesToEven);
1516        return ConstantFP::get(Ty->getContext(), V);
1517      }
1518
1519      /// We only fold functions with finite arguments. Folding NaN and inf is
1520      /// likely to be aborted with an exception anyway, and some host libms
1521      /// have known errors raising exceptions.
1522      if (Op->getValueAPF().isNaN() || Op->getValueAPF().isInfinity())
1523        return nullptr;
1524
1525      /// Currently APFloat versions of these functions do not exist, so we use
1526      /// the host native double versions.  Float versions are not called
1527      /// directly but for all these it is true (float)(f((double)arg)) ==
1528      /// f(arg).  Long double not supported yet.
1529      double V = getValueAsDouble(Op);
1530
1531      switch (IntrinsicID) {
1532        default: break;
1533        case Intrinsic::fabs:
1534          return ConstantFoldFP(fabs, V, Ty);
1535        case Intrinsic::log2:
1536          return ConstantFoldFP(Log2, V, Ty);
1537        case Intrinsic::log:
1538          return ConstantFoldFP(log, V, Ty);
1539        case Intrinsic::log10:
1540          return ConstantFoldFP(log10, V, Ty);
1541        case Intrinsic::exp:
1542          return ConstantFoldFP(exp, V, Ty);
1543        case Intrinsic::exp2:
1544          return ConstantFoldFP(exp2, V, Ty);
1545        case Intrinsic::sin:
1546          return ConstantFoldFP(sin, V, Ty);
1547        case Intrinsic::cos:
1548          return ConstantFoldFP(cos, V, Ty);
1549      }
1550
1551      if (!TLI)
1552        return nullptr;
1553
1554      switch (Name[0]) {
1555      case 'a':
1556        if ((Name == "acos" && TLI->has(LibFunc::acos)) ||
1557            (Name == "acosf" && TLI->has(LibFunc::acosf)))
1558          return ConstantFoldFP(acos, V, Ty);
1559        else if ((Name == "asin" && TLI->has(LibFunc::asin)) ||
1560                 (Name == "asinf" && TLI->has(LibFunc::asinf)))
1561          return ConstantFoldFP(asin, V, Ty);
1562        else if ((Name == "atan" && TLI->has(LibFunc::atan)) ||
1563                 (Name == "atanf" && TLI->has(LibFunc::atanf)))
1564          return ConstantFoldFP(atan, V, Ty);
1565        break;
1566      case 'c':
1567        if ((Name == "ceil" && TLI->has(LibFunc::ceil)) ||
1568            (Name == "ceilf" && TLI->has(LibFunc::ceilf)))
1569          return ConstantFoldFP(ceil, V, Ty);
1570        else if ((Name == "cos" && TLI->has(LibFunc::cos)) ||
1571                 (Name == "cosf" && TLI->has(LibFunc::cosf)))
1572          return ConstantFoldFP(cos, V, Ty);
1573        else if ((Name == "cosh" && TLI->has(LibFunc::cosh)) ||
1574                 (Name == "coshf" && TLI->has(LibFunc::coshf)))
1575          return ConstantFoldFP(cosh, V, Ty);
1576        break;
1577      case 'e':
1578        if ((Name == "exp" && TLI->has(LibFunc::exp)) ||
1579            (Name == "expf" && TLI->has(LibFunc::expf)))
1580          return ConstantFoldFP(exp, V, Ty);
1581        if ((Name == "exp2" && TLI->has(LibFunc::exp2)) ||
1582            (Name == "exp2f" && TLI->has(LibFunc::exp2f)))
1583          // Constant fold exp2(x) as pow(2,x) in case the host doesn't have a
1584          // C99 library.
1585          return ConstantFoldBinaryFP(pow, 2.0, V, Ty);
1586        break;
1587      case 'f':
1588        if ((Name == "fabs" && TLI->has(LibFunc::fabs)) ||
1589            (Name == "fabsf" && TLI->has(LibFunc::fabsf)))
1590          return ConstantFoldFP(fabs, V, Ty);
1591        else if ((Name == "floor" && TLI->has(LibFunc::floor)) ||
1592                 (Name == "floorf" && TLI->has(LibFunc::floorf)))
1593          return ConstantFoldFP(floor, V, Ty);
1594        break;
1595      case 'l':
1596        if ((Name == "log" && V > 0 && TLI->has(LibFunc::log)) ||
1597            (Name == "logf" && V > 0 && TLI->has(LibFunc::logf)))
1598          return ConstantFoldFP(log, V, Ty);
1599        else if ((Name == "log10" && V > 0 && TLI->has(LibFunc::log10)) ||
1600                 (Name == "log10f" && V > 0 && TLI->has(LibFunc::log10f)))
1601          return ConstantFoldFP(log10, V, Ty);
1602        else if (IntrinsicID == Intrinsic::sqrt &&
1603                 (Ty->isHalfTy() || Ty->isFloatTy() || Ty->isDoubleTy())) {
1604          if (V >= -0.0)
1605            return ConstantFoldFP(sqrt, V, Ty);
1606          else {
1607            // Unlike the sqrt definitions in C/C++, POSIX, and IEEE-754 - which
1608            // all guarantee or favor returning NaN - the square root of a
1609            // negative number is not defined for the LLVM sqrt intrinsic.
1610            // This is because the intrinsic should only be emitted in place of
1611            // libm's sqrt function when using "no-nans-fp-math".
1612            return UndefValue::get(Ty);
1613          }
1614        }
1615        break;
1616      case 's':
1617        if ((Name == "sin" && TLI->has(LibFunc::sin)) ||
1618            (Name == "sinf" && TLI->has(LibFunc::sinf)))
1619          return ConstantFoldFP(sin, V, Ty);
1620        else if ((Name == "sinh" && TLI->has(LibFunc::sinh)) ||
1621                 (Name == "sinhf" && TLI->has(LibFunc::sinhf)))
1622          return ConstantFoldFP(sinh, V, Ty);
1623        else if ((Name == "sqrt" && V >= 0 && TLI->has(LibFunc::sqrt)) ||
1624                 (Name == "sqrtf" && V >= 0 && TLI->has(LibFunc::sqrtf)))
1625          return ConstantFoldFP(sqrt, V, Ty);
1626        break;
1627      case 't':
1628        if ((Name == "tan" && TLI->has(LibFunc::tan)) ||
1629            (Name == "tanf" && TLI->has(LibFunc::tanf)))
1630          return ConstantFoldFP(tan, V, Ty);
1631        else if ((Name == "tanh" && TLI->has(LibFunc::tanh)) ||
1632                 (Name == "tanhf" && TLI->has(LibFunc::tanhf)))
1633          return ConstantFoldFP(tanh, V, Ty);
1634        break;
1635      default:
1636        break;
1637      }
1638      return nullptr;
1639    }
1640
1641    if (auto *Op = dyn_cast<ConstantInt>(Operands[0])) {
1642      switch (IntrinsicID) {
1643      case Intrinsic::bswap:
1644        return ConstantInt::get(Ty->getContext(), Op->getValue().byteSwap());
1645      case Intrinsic::ctpop:
1646        return ConstantInt::get(Ty, Op->getValue().countPopulation());
1647      case Intrinsic::bitreverse:
1648        return ConstantInt::get(Ty->getContext(), Op->getValue().reverseBits());
1649      case Intrinsic::convert_from_fp16: {
1650        APFloat Val(APFloat::IEEEhalf, Op->getValue());
1651
1652        bool lost = false;
1653        APFloat::opStatus status = Val.convert(
1654            Ty->getFltSemantics(), APFloat::rmNearestTiesToEven, &lost);
1655
1656        // Conversion is always precise.
1657        (void)status;
1658        assert(status == APFloat::opOK && !lost &&
1659               "Precision lost during fp16 constfolding");
1660
1661        return ConstantFP::get(Ty->getContext(), Val);
1662      }
1663      default:
1664        return nullptr;
1665      }
1666    }
1667
1668    // Support ConstantVector in case we have an Undef in the top.
1669    if (isa<ConstantVector>(Operands[0]) ||
1670        isa<ConstantDataVector>(Operands[0])) {
1671      auto *Op = cast<Constant>(Operands[0]);
1672      switch (IntrinsicID) {
1673      default: break;
1674      case Intrinsic::x86_sse_cvtss2si:
1675      case Intrinsic::x86_sse_cvtss2si64:
1676      case Intrinsic::x86_sse2_cvtsd2si:
1677      case Intrinsic::x86_sse2_cvtsd2si64:
1678        if (ConstantFP *FPOp =
1679              dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
1680          return ConstantFoldConvertToInt(FPOp->getValueAPF(),
1681                                          /*roundTowardZero=*/false, Ty);
1682      case Intrinsic::x86_sse_cvttss2si:
1683      case Intrinsic::x86_sse_cvttss2si64:
1684      case Intrinsic::x86_sse2_cvttsd2si:
1685      case Intrinsic::x86_sse2_cvttsd2si64:
1686        if (ConstantFP *FPOp =
1687              dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
1688          return ConstantFoldConvertToInt(FPOp->getValueAPF(),
1689                                          /*roundTowardZero=*/true, Ty);
1690      }
1691    }
1692
1693    if (isa<UndefValue>(Operands[0])) {
1694      if (IntrinsicID == Intrinsic::bswap)
1695        return Operands[0];
1696      return nullptr;
1697    }
1698
1699    return nullptr;
1700  }
1701
1702  if (Operands.size() == 2) {
1703    if (auto *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
1704      if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
1705        return nullptr;
1706      double Op1V = getValueAsDouble(Op1);
1707
1708      if (auto *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
1709        if (Op2->getType() != Op1->getType())
1710          return nullptr;
1711
1712        double Op2V = getValueAsDouble(Op2);
1713        if (IntrinsicID == Intrinsic::pow) {
1714          return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
1715        }
1716        if (IntrinsicID == Intrinsic::copysign) {
1717          APFloat V1 = Op1->getValueAPF();
1718          const APFloat &V2 = Op2->getValueAPF();
1719          V1.copySign(V2);
1720          return ConstantFP::get(Ty->getContext(), V1);
1721        }
1722
1723        if (IntrinsicID == Intrinsic::minnum) {
1724          const APFloat &C1 = Op1->getValueAPF();
1725          const APFloat &C2 = Op2->getValueAPF();
1726          return ConstantFP::get(Ty->getContext(), minnum(C1, C2));
1727        }
1728
1729        if (IntrinsicID == Intrinsic::maxnum) {
1730          const APFloat &C1 = Op1->getValueAPF();
1731          const APFloat &C2 = Op2->getValueAPF();
1732          return ConstantFP::get(Ty->getContext(), maxnum(C1, C2));
1733        }
1734
1735        if (!TLI)
1736          return nullptr;
1737        if ((Name == "pow" && TLI->has(LibFunc::pow)) ||
1738            (Name == "powf" && TLI->has(LibFunc::powf)))
1739          return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
1740        if ((Name == "fmod" && TLI->has(LibFunc::fmod)) ||
1741            (Name == "fmodf" && TLI->has(LibFunc::fmodf)))
1742          return ConstantFoldBinaryFP(fmod, Op1V, Op2V, Ty);
1743        if ((Name == "atan2" && TLI->has(LibFunc::atan2)) ||
1744            (Name == "atan2f" && TLI->has(LibFunc::atan2f)))
1745          return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
1746      } else if (auto *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
1747        if (IntrinsicID == Intrinsic::powi && Ty->isHalfTy())
1748          return ConstantFP::get(Ty->getContext(),
1749                                 APFloat((float)std::pow((float)Op1V,
1750                                                 (int)Op2C->getZExtValue())));
1751        if (IntrinsicID == Intrinsic::powi && Ty->isFloatTy())
1752          return ConstantFP::get(Ty->getContext(),
1753                                 APFloat((float)std::pow((float)Op1V,
1754                                                 (int)Op2C->getZExtValue())));
1755        if (IntrinsicID == Intrinsic::powi && Ty->isDoubleTy())
1756          return ConstantFP::get(Ty->getContext(),
1757                                 APFloat((double)std::pow((double)Op1V,
1758                                                   (int)Op2C->getZExtValue())));
1759      }
1760      return nullptr;
1761    }
1762
1763    if (auto *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
1764      if (auto *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
1765        switch (IntrinsicID) {
1766        default: break;
1767        case Intrinsic::sadd_with_overflow:
1768        case Intrinsic::uadd_with_overflow:
1769        case Intrinsic::ssub_with_overflow:
1770        case Intrinsic::usub_with_overflow:
1771        case Intrinsic::smul_with_overflow:
1772        case Intrinsic::umul_with_overflow: {
1773          APInt Res;
1774          bool Overflow;
1775          switch (IntrinsicID) {
1776          default: llvm_unreachable("Invalid case");
1777          case Intrinsic::sadd_with_overflow:
1778            Res = Op1->getValue().sadd_ov(Op2->getValue(), Overflow);
1779            break;
1780          case Intrinsic::uadd_with_overflow:
1781            Res = Op1->getValue().uadd_ov(Op2->getValue(), Overflow);
1782            break;
1783          case Intrinsic::ssub_with_overflow:
1784            Res = Op1->getValue().ssub_ov(Op2->getValue(), Overflow);
1785            break;
1786          case Intrinsic::usub_with_overflow:
1787            Res = Op1->getValue().usub_ov(Op2->getValue(), Overflow);
1788            break;
1789          case Intrinsic::smul_with_overflow:
1790            Res = Op1->getValue().smul_ov(Op2->getValue(), Overflow);
1791            break;
1792          case Intrinsic::umul_with_overflow:
1793            Res = Op1->getValue().umul_ov(Op2->getValue(), Overflow);
1794            break;
1795          }
1796          Constant *Ops[] = {
1797            ConstantInt::get(Ty->getContext(), Res),
1798            ConstantInt::get(Type::getInt1Ty(Ty->getContext()), Overflow)
1799          };
1800          return ConstantStruct::get(cast<StructType>(Ty), Ops);
1801        }
1802        case Intrinsic::cttz:
1803          if (Op2->isOne() && Op1->isZero()) // cttz(0, 1) is undef.
1804            return UndefValue::get(Ty);
1805          return ConstantInt::get(Ty, Op1->getValue().countTrailingZeros());
1806        case Intrinsic::ctlz:
1807          if (Op2->isOne() && Op1->isZero()) // ctlz(0, 1) is undef.
1808            return UndefValue::get(Ty);
1809          return ConstantInt::get(Ty, Op1->getValue().countLeadingZeros());
1810        }
1811      }
1812
1813      return nullptr;
1814    }
1815    return nullptr;
1816  }
1817
1818  if (Operands.size() != 3)
1819    return nullptr;
1820
1821  if (const auto *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
1822    if (const auto *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
1823      if (const auto *Op3 = dyn_cast<ConstantFP>(Operands[2])) {
1824        switch (IntrinsicID) {
1825        default: break;
1826        case Intrinsic::fma:
1827        case Intrinsic::fmuladd: {
1828          APFloat V = Op1->getValueAPF();
1829          APFloat::opStatus s = V.fusedMultiplyAdd(Op2->getValueAPF(),
1830                                                   Op3->getValueAPF(),
1831                                                   APFloat::rmNearestTiesToEven);
1832          if (s != APFloat::opInvalidOp)
1833            return ConstantFP::get(Ty->getContext(), V);
1834
1835          return nullptr;
1836        }
1837        }
1838      }
1839    }
1840  }
1841
1842  return nullptr;
1843}
1844
1845Constant *ConstantFoldVectorCall(StringRef Name, unsigned IntrinsicID,
1846                                 VectorType *VTy, ArrayRef<Constant *> Operands,
1847                                 const DataLayout &DL,
1848                                 const TargetLibraryInfo *TLI) {
1849  SmallVector<Constant *, 4> Result(VTy->getNumElements());
1850  SmallVector<Constant *, 4> Lane(Operands.size());
1851  Type *Ty = VTy->getElementType();
1852
1853  if (IntrinsicID == Intrinsic::masked_load) {
1854    auto *SrcPtr = Operands[0];
1855    auto *Mask = Operands[2];
1856    auto *Passthru = Operands[3];
1857
1858    Constant *VecData = ConstantFoldLoadFromConstPtr(SrcPtr, VTy, DL);
1859
1860    SmallVector<Constant *, 32> NewElements;
1861    for (unsigned I = 0, E = VTy->getNumElements(); I != E; ++I) {
1862      auto *MaskElt = Mask->getAggregateElement(I);
1863      if (!MaskElt)
1864        break;
1865      auto *PassthruElt = Passthru->getAggregateElement(I);
1866      auto *VecElt = VecData ? VecData->getAggregateElement(I) : nullptr;
1867      if (isa<UndefValue>(MaskElt)) {
1868        if (PassthruElt)
1869          NewElements.push_back(PassthruElt);
1870        else if (VecElt)
1871          NewElements.push_back(VecElt);
1872        else
1873          return nullptr;
1874      }
1875      if (MaskElt->isNullValue()) {
1876        if (!PassthruElt)
1877          return nullptr;
1878        NewElements.push_back(PassthruElt);
1879      } else if (MaskElt->isOneValue()) {
1880        if (!VecElt)
1881          return nullptr;
1882        NewElements.push_back(VecElt);
1883      } else {
1884        return nullptr;
1885      }
1886    }
1887    if (NewElements.size() != VTy->getNumElements())
1888      return nullptr;
1889    return ConstantVector::get(NewElements);
1890  }
1891
1892  for (unsigned I = 0, E = VTy->getNumElements(); I != E; ++I) {
1893    // Gather a column of constants.
1894    for (unsigned J = 0, JE = Operands.size(); J != JE; ++J) {
1895      Constant *Agg = Operands[J]->getAggregateElement(I);
1896      if (!Agg)
1897        return nullptr;
1898
1899      Lane[J] = Agg;
1900    }
1901
1902    // Use the regular scalar folding to simplify this column.
1903    Constant *Folded = ConstantFoldScalarCall(Name, IntrinsicID, Ty, Lane, TLI);
1904    if (!Folded)
1905      return nullptr;
1906    Result[I] = Folded;
1907  }
1908
1909  return ConstantVector::get(Result);
1910}
1911
1912} // end anonymous namespace
1913
1914Constant *
1915llvm::ConstantFoldCall(Function *F, ArrayRef<Constant *> Operands,
1916                       const TargetLibraryInfo *TLI) {
1917  if (!F->hasName())
1918    return nullptr;
1919  StringRef Name = F->getName();
1920
1921  Type *Ty = F->getReturnType();
1922
1923  if (auto *VTy = dyn_cast<VectorType>(Ty))
1924    return ConstantFoldVectorCall(Name, F->getIntrinsicID(), VTy, Operands,
1925                                  F->getParent()->getDataLayout(), TLI);
1926
1927  return ConstantFoldScalarCall(Name, F->getIntrinsicID(), Ty, Operands, TLI);
1928}
1929