xref: /freebsd/contrib/llvm-project/llvm/lib/Analysis/ConstantFolding.cpp (revision c1d255d3ffdbe447de3ab875bf4e7d7accc5bfc5)
1 //===-- ConstantFolding.cpp - Fold instructions into constants ------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines routines for folding instructions into constants.
10 //
11 // Also, to supplement the basic IR ConstantExpr simplifications,
12 // this file defines some additional folding routines that can make use of
13 // DataLayout information. These functions cannot go in IR due to library
14 // dependency issues.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #include "llvm/Analysis/ConstantFolding.h"
19 #include "llvm/ADT/APFloat.h"
20 #include "llvm/ADT/APInt.h"
21 #include "llvm/ADT/APSInt.h"
22 #include "llvm/ADT/ArrayRef.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/ADT/STLExtras.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/Analysis/TargetFolder.h"
28 #include "llvm/Analysis/TargetLibraryInfo.h"
29 #include "llvm/Analysis/ValueTracking.h"
30 #include "llvm/Analysis/VectorUtils.h"
31 #include "llvm/Config/config.h"
32 #include "llvm/IR/Constant.h"
33 #include "llvm/IR/Constants.h"
34 #include "llvm/IR/DataLayout.h"
35 #include "llvm/IR/DerivedTypes.h"
36 #include "llvm/IR/Function.h"
37 #include "llvm/IR/GlobalValue.h"
38 #include "llvm/IR/GlobalVariable.h"
39 #include "llvm/IR/InstrTypes.h"
40 #include "llvm/IR/Instruction.h"
41 #include "llvm/IR/Instructions.h"
42 #include "llvm/IR/IntrinsicInst.h"
43 #include "llvm/IR/Intrinsics.h"
44 #include "llvm/IR/IntrinsicsAMDGPU.h"
45 #include "llvm/IR/IntrinsicsARM.h"
46 #include "llvm/IR/IntrinsicsWebAssembly.h"
47 #include "llvm/IR/IntrinsicsX86.h"
48 #include "llvm/IR/Operator.h"
49 #include "llvm/IR/Type.h"
50 #include "llvm/IR/Value.h"
51 #include "llvm/Support/Casting.h"
52 #include "llvm/Support/ErrorHandling.h"
53 #include "llvm/Support/KnownBits.h"
54 #include "llvm/Support/MathExtras.h"
55 #include <cassert>
56 #include <cerrno>
57 #include <cfenv>
58 #include <cmath>
59 #include <cstddef>
60 #include <cstdint>
61 
62 using namespace llvm;
63 
64 namespace {
65 
66 //===----------------------------------------------------------------------===//
67 // Constant Folding internal helper functions
68 //===----------------------------------------------------------------------===//
69 
70 static Constant *foldConstVectorToAPInt(APInt &Result, Type *DestTy,
71                                         Constant *C, Type *SrcEltTy,
72                                         unsigned NumSrcElts,
73                                         const DataLayout &DL) {
74   // Now that we know that the input value is a vector of integers, just shift
75   // and insert them into our result.
76   unsigned BitShift = DL.getTypeSizeInBits(SrcEltTy);
77   for (unsigned i = 0; i != NumSrcElts; ++i) {
78     Constant *Element;
79     if (DL.isLittleEndian())
80       Element = C->getAggregateElement(NumSrcElts - i - 1);
81     else
82       Element = C->getAggregateElement(i);
83 
84     if (Element && isa<UndefValue>(Element)) {
85       Result <<= BitShift;
86       continue;
87     }
88 
89     auto *ElementCI = dyn_cast_or_null<ConstantInt>(Element);
90     if (!ElementCI)
91       return ConstantExpr::getBitCast(C, DestTy);
92 
93     Result <<= BitShift;
94     Result |= ElementCI->getValue().zextOrSelf(Result.getBitWidth());
95   }
96 
97   return nullptr;
98 }
99 
100 /// Constant fold bitcast, symbolically evaluating it with DataLayout.
101 /// This always returns a non-null constant, but it may be a
102 /// ConstantExpr if unfoldable.
103 Constant *FoldBitCast(Constant *C, Type *DestTy, const DataLayout &DL) {
104   assert(CastInst::castIsValid(Instruction::BitCast, C, DestTy) &&
105          "Invalid constantexpr bitcast!");
106 
107   // Catch the obvious splat cases.
108   if (C->isNullValue() && !DestTy->isX86_MMXTy() && !DestTy->isX86_AMXTy())
109     return Constant::getNullValue(DestTy);
110   if (C->isAllOnesValue() && !DestTy->isX86_MMXTy() && !DestTy->isX86_AMXTy() &&
111       !DestTy->isPtrOrPtrVectorTy()) // Don't get ones for ptr types!
112     return Constant::getAllOnesValue(DestTy);
113 
114   if (auto *VTy = dyn_cast<VectorType>(C->getType())) {
115     // Handle a vector->scalar integer/fp cast.
116     if (isa<IntegerType>(DestTy) || DestTy->isFloatingPointTy()) {
117       unsigned NumSrcElts = cast<FixedVectorType>(VTy)->getNumElements();
118       Type *SrcEltTy = VTy->getElementType();
119 
120       // If the vector is a vector of floating point, convert it to vector of int
121       // to simplify things.
122       if (SrcEltTy->isFloatingPointTy()) {
123         unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
124         auto *SrcIVTy = FixedVectorType::get(
125             IntegerType::get(C->getContext(), FPWidth), NumSrcElts);
126         // Ask IR to do the conversion now that #elts line up.
127         C = ConstantExpr::getBitCast(C, SrcIVTy);
128       }
129 
130       APInt Result(DL.getTypeSizeInBits(DestTy), 0);
131       if (Constant *CE = foldConstVectorToAPInt(Result, DestTy, C,
132                                                 SrcEltTy, NumSrcElts, DL))
133         return CE;
134 
135       if (isa<IntegerType>(DestTy))
136         return ConstantInt::get(DestTy, Result);
137 
138       APFloat FP(DestTy->getFltSemantics(), Result);
139       return ConstantFP::get(DestTy->getContext(), FP);
140     }
141   }
142 
143   // The code below only handles casts to vectors currently.
144   auto *DestVTy = dyn_cast<VectorType>(DestTy);
145   if (!DestVTy)
146     return ConstantExpr::getBitCast(C, DestTy);
147 
148   // If this is a scalar -> vector cast, convert the input into a <1 x scalar>
149   // vector so the code below can handle it uniformly.
150   if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
151     Constant *Ops = C; // don't take the address of C!
152     return FoldBitCast(ConstantVector::get(Ops), DestTy, DL);
153   }
154 
155   // If this is a bitcast from constant vector -> vector, fold it.
156   if (!isa<ConstantDataVector>(C) && !isa<ConstantVector>(C))
157     return ConstantExpr::getBitCast(C, DestTy);
158 
159   // If the element types match, IR can fold it.
160   unsigned NumDstElt = cast<FixedVectorType>(DestVTy)->getNumElements();
161   unsigned NumSrcElt = cast<FixedVectorType>(C->getType())->getNumElements();
162   if (NumDstElt == NumSrcElt)
163     return ConstantExpr::getBitCast(C, DestTy);
164 
165   Type *SrcEltTy = cast<VectorType>(C->getType())->getElementType();
166   Type *DstEltTy = DestVTy->getElementType();
167 
168   // Otherwise, we're changing the number of elements in a vector, which
169   // requires endianness information to do the right thing.  For example,
170   //    bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
171   // folds to (little endian):
172   //    <4 x i32> <i32 0, i32 0, i32 1, i32 0>
173   // and to (big endian):
174   //    <4 x i32> <i32 0, i32 0, i32 0, i32 1>
175 
176   // First thing is first.  We only want to think about integer here, so if
177   // we have something in FP form, recast it as integer.
178   if (DstEltTy->isFloatingPointTy()) {
179     // Fold to an vector of integers with same size as our FP type.
180     unsigned FPWidth = DstEltTy->getPrimitiveSizeInBits();
181     auto *DestIVTy = FixedVectorType::get(
182         IntegerType::get(C->getContext(), FPWidth), NumDstElt);
183     // Recursively handle this integer conversion, if possible.
184     C = FoldBitCast(C, DestIVTy, DL);
185 
186     // Finally, IR can handle this now that #elts line up.
187     return ConstantExpr::getBitCast(C, DestTy);
188   }
189 
190   // Okay, we know the destination is integer, if the input is FP, convert
191   // it to integer first.
192   if (SrcEltTy->isFloatingPointTy()) {
193     unsigned FPWidth = SrcEltTy->getPrimitiveSizeInBits();
194     auto *SrcIVTy = FixedVectorType::get(
195         IntegerType::get(C->getContext(), FPWidth), NumSrcElt);
196     // Ask IR to do the conversion now that #elts line up.
197     C = ConstantExpr::getBitCast(C, SrcIVTy);
198     // If IR wasn't able to fold it, bail out.
199     if (!isa<ConstantVector>(C) &&  // FIXME: Remove ConstantVector.
200         !isa<ConstantDataVector>(C))
201       return C;
202   }
203 
204   // Now we know that the input and output vectors are both integer vectors
205   // of the same size, and that their #elements is not the same.  Do the
206   // conversion here, which depends on whether the input or output has
207   // more elements.
208   bool isLittleEndian = DL.isLittleEndian();
209 
210   SmallVector<Constant*, 32> Result;
211   if (NumDstElt < NumSrcElt) {
212     // Handle: bitcast (<4 x i32> <i32 0, i32 1, i32 2, i32 3> to <2 x i64>)
213     Constant *Zero = Constant::getNullValue(DstEltTy);
214     unsigned Ratio = NumSrcElt/NumDstElt;
215     unsigned SrcBitSize = SrcEltTy->getPrimitiveSizeInBits();
216     unsigned SrcElt = 0;
217     for (unsigned i = 0; i != NumDstElt; ++i) {
218       // Build each element of the result.
219       Constant *Elt = Zero;
220       unsigned ShiftAmt = isLittleEndian ? 0 : SrcBitSize*(Ratio-1);
221       for (unsigned j = 0; j != Ratio; ++j) {
222         Constant *Src = C->getAggregateElement(SrcElt++);
223         if (Src && isa<UndefValue>(Src))
224           Src = Constant::getNullValue(
225               cast<VectorType>(C->getType())->getElementType());
226         else
227           Src = dyn_cast_or_null<ConstantInt>(Src);
228         if (!Src)  // Reject constantexpr elements.
229           return ConstantExpr::getBitCast(C, DestTy);
230 
231         // Zero extend the element to the right size.
232         Src = ConstantExpr::getZExt(Src, Elt->getType());
233 
234         // Shift it to the right place, depending on endianness.
235         Src = ConstantExpr::getShl(Src,
236                                    ConstantInt::get(Src->getType(), ShiftAmt));
237         ShiftAmt += isLittleEndian ? SrcBitSize : -SrcBitSize;
238 
239         // Mix it in.
240         Elt = ConstantExpr::getOr(Elt, Src);
241       }
242       Result.push_back(Elt);
243     }
244     return ConstantVector::get(Result);
245   }
246 
247   // Handle: bitcast (<2 x i64> <i64 0, i64 1> to <4 x i32>)
248   unsigned Ratio = NumDstElt/NumSrcElt;
249   unsigned DstBitSize = DL.getTypeSizeInBits(DstEltTy);
250 
251   // Loop over each source value, expanding into multiple results.
252   for (unsigned i = 0; i != NumSrcElt; ++i) {
253     auto *Element = C->getAggregateElement(i);
254 
255     if (!Element) // Reject constantexpr elements.
256       return ConstantExpr::getBitCast(C, DestTy);
257 
258     if (isa<UndefValue>(Element)) {
259       // Correctly Propagate undef values.
260       Result.append(Ratio, UndefValue::get(DstEltTy));
261       continue;
262     }
263 
264     auto *Src = dyn_cast<ConstantInt>(Element);
265     if (!Src)
266       return ConstantExpr::getBitCast(C, DestTy);
267 
268     unsigned ShiftAmt = isLittleEndian ? 0 : DstBitSize*(Ratio-1);
269     for (unsigned j = 0; j != Ratio; ++j) {
270       // Shift the piece of the value into the right place, depending on
271       // endianness.
272       Constant *Elt = ConstantExpr::getLShr(Src,
273                                   ConstantInt::get(Src->getType(), ShiftAmt));
274       ShiftAmt += isLittleEndian ? DstBitSize : -DstBitSize;
275 
276       // Truncate the element to an integer with the same pointer size and
277       // convert the element back to a pointer using a inttoptr.
278       if (DstEltTy->isPointerTy()) {
279         IntegerType *DstIntTy = Type::getIntNTy(C->getContext(), DstBitSize);
280         Constant *CE = ConstantExpr::getTrunc(Elt, DstIntTy);
281         Result.push_back(ConstantExpr::getIntToPtr(CE, DstEltTy));
282         continue;
283       }
284 
285       // Truncate and remember this piece.
286       Result.push_back(ConstantExpr::getTrunc(Elt, DstEltTy));
287     }
288   }
289 
290   return ConstantVector::get(Result);
291 }
292 
293 } // end anonymous namespace
294 
295 /// If this constant is a constant offset from a global, return the global and
296 /// the constant. Because of constantexprs, this function is recursive.
297 bool llvm::IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
298                                       APInt &Offset, const DataLayout &DL,
299                                       DSOLocalEquivalent **DSOEquiv) {
300   if (DSOEquiv)
301     *DSOEquiv = nullptr;
302 
303   // Trivial case, constant is the global.
304   if ((GV = dyn_cast<GlobalValue>(C))) {
305     unsigned BitWidth = DL.getIndexTypeSizeInBits(GV->getType());
306     Offset = APInt(BitWidth, 0);
307     return true;
308   }
309 
310   if (auto *FoundDSOEquiv = dyn_cast<DSOLocalEquivalent>(C)) {
311     if (DSOEquiv)
312       *DSOEquiv = FoundDSOEquiv;
313     GV = FoundDSOEquiv->getGlobalValue();
314     unsigned BitWidth = DL.getIndexTypeSizeInBits(GV->getType());
315     Offset = APInt(BitWidth, 0);
316     return true;
317   }
318 
319   // Otherwise, if this isn't a constant expr, bail out.
320   auto *CE = dyn_cast<ConstantExpr>(C);
321   if (!CE) return false;
322 
323   // Look through ptr->int and ptr->ptr casts.
324   if (CE->getOpcode() == Instruction::PtrToInt ||
325       CE->getOpcode() == Instruction::BitCast)
326     return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, DL,
327                                       DSOEquiv);
328 
329   // i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
330   auto *GEP = dyn_cast<GEPOperator>(CE);
331   if (!GEP)
332     return false;
333 
334   unsigned BitWidth = DL.getIndexTypeSizeInBits(GEP->getType());
335   APInt TmpOffset(BitWidth, 0);
336 
337   // If the base isn't a global+constant, we aren't either.
338   if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, TmpOffset, DL,
339                                   DSOEquiv))
340     return false;
341 
342   // Otherwise, add any offset that our operands provide.
343   if (!GEP->accumulateConstantOffset(DL, TmpOffset))
344     return false;
345 
346   Offset = TmpOffset;
347   return true;
348 }
349 
350 Constant *llvm::ConstantFoldLoadThroughBitcast(Constant *C, Type *DestTy,
351                                          const DataLayout &DL) {
352   do {
353     Type *SrcTy = C->getType();
354     uint64_t DestSize = DL.getTypeSizeInBits(DestTy);
355     uint64_t SrcSize = DL.getTypeSizeInBits(SrcTy);
356     if (SrcSize < DestSize)
357       return nullptr;
358 
359     // Catch the obvious splat cases (since all-zeros can coerce non-integral
360     // pointers legally).
361     if (C->isNullValue() && !DestTy->isX86_MMXTy() && !DestTy->isX86_AMXTy())
362       return Constant::getNullValue(DestTy);
363     if (C->isAllOnesValue() &&
364         (DestTy->isIntegerTy() || DestTy->isFloatingPointTy() ||
365          DestTy->isVectorTy()) &&
366         !DestTy->isX86_AMXTy() && !DestTy->isX86_MMXTy() &&
367         !DestTy->isPtrOrPtrVectorTy())
368       // Get ones when the input is trivial, but
369       // only for supported types inside getAllOnesValue.
370       return Constant::getAllOnesValue(DestTy);
371 
372     // If the type sizes are the same and a cast is legal, just directly
373     // cast the constant.
374     // But be careful not to coerce non-integral pointers illegally.
375     if (SrcSize == DestSize &&
376         DL.isNonIntegralPointerType(SrcTy->getScalarType()) ==
377             DL.isNonIntegralPointerType(DestTy->getScalarType())) {
378       Instruction::CastOps Cast = Instruction::BitCast;
379       // If we are going from a pointer to int or vice versa, we spell the cast
380       // differently.
381       if (SrcTy->isIntegerTy() && DestTy->isPointerTy())
382         Cast = Instruction::IntToPtr;
383       else if (SrcTy->isPointerTy() && DestTy->isIntegerTy())
384         Cast = Instruction::PtrToInt;
385 
386       if (CastInst::castIsValid(Cast, C, DestTy))
387         return ConstantExpr::getCast(Cast, C, DestTy);
388     }
389 
390     // If this isn't an aggregate type, there is nothing we can do to drill down
391     // and find a bitcastable constant.
392     if (!SrcTy->isAggregateType())
393       return nullptr;
394 
395     // We're simulating a load through a pointer that was bitcast to point to
396     // a different type, so we can try to walk down through the initial
397     // elements of an aggregate to see if some part of the aggregate is
398     // castable to implement the "load" semantic model.
399     if (SrcTy->isStructTy()) {
400       // Struct types might have leading zero-length elements like [0 x i32],
401       // which are certainly not what we are looking for, so skip them.
402       unsigned Elem = 0;
403       Constant *ElemC;
404       do {
405         ElemC = C->getAggregateElement(Elem++);
406       } while (ElemC && DL.getTypeSizeInBits(ElemC->getType()).isZero());
407       C = ElemC;
408     } else {
409       C = C->getAggregateElement(0u);
410     }
411   } while (C);
412 
413   return nullptr;
414 }
415 
416 namespace {
417 
418 /// Recursive helper to read bits out of global. C is the constant being copied
419 /// out of. ByteOffset is an offset into C. CurPtr is the pointer to copy
420 /// results into and BytesLeft is the number of bytes left in
421 /// the CurPtr buffer. DL is the DataLayout.
422 bool ReadDataFromGlobal(Constant *C, uint64_t ByteOffset, unsigned char *CurPtr,
423                         unsigned BytesLeft, const DataLayout &DL) {
424   assert(ByteOffset <= DL.getTypeAllocSize(C->getType()) &&
425          "Out of range access");
426 
427   // If this element is zero or undefined, we can just return since *CurPtr is
428   // zero initialized.
429   if (isa<ConstantAggregateZero>(C) || isa<UndefValue>(C))
430     return true;
431 
432   if (auto *CI = dyn_cast<ConstantInt>(C)) {
433     if (CI->getBitWidth() > 64 ||
434         (CI->getBitWidth() & 7) != 0)
435       return false;
436 
437     uint64_t Val = CI->getZExtValue();
438     unsigned IntBytes = unsigned(CI->getBitWidth()/8);
439 
440     for (unsigned i = 0; i != BytesLeft && ByteOffset != IntBytes; ++i) {
441       int n = ByteOffset;
442       if (!DL.isLittleEndian())
443         n = IntBytes - n - 1;
444       CurPtr[i] = (unsigned char)(Val >> (n * 8));
445       ++ByteOffset;
446     }
447     return true;
448   }
449 
450   if (auto *CFP = dyn_cast<ConstantFP>(C)) {
451     if (CFP->getType()->isDoubleTy()) {
452       C = FoldBitCast(C, Type::getInt64Ty(C->getContext()), DL);
453       return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
454     }
455     if (CFP->getType()->isFloatTy()){
456       C = FoldBitCast(C, Type::getInt32Ty(C->getContext()), DL);
457       return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
458     }
459     if (CFP->getType()->isHalfTy()){
460       C = FoldBitCast(C, Type::getInt16Ty(C->getContext()), DL);
461       return ReadDataFromGlobal(C, ByteOffset, CurPtr, BytesLeft, DL);
462     }
463     return false;
464   }
465 
466   if (auto *CS = dyn_cast<ConstantStruct>(C)) {
467     const StructLayout *SL = DL.getStructLayout(CS->getType());
468     unsigned Index = SL->getElementContainingOffset(ByteOffset);
469     uint64_t CurEltOffset = SL->getElementOffset(Index);
470     ByteOffset -= CurEltOffset;
471 
472     while (true) {
473       // If the element access is to the element itself and not to tail padding,
474       // read the bytes from the element.
475       uint64_t EltSize = DL.getTypeAllocSize(CS->getOperand(Index)->getType());
476 
477       if (ByteOffset < EltSize &&
478           !ReadDataFromGlobal(CS->getOperand(Index), ByteOffset, CurPtr,
479                               BytesLeft, DL))
480         return false;
481 
482       ++Index;
483 
484       // Check to see if we read from the last struct element, if so we're done.
485       if (Index == CS->getType()->getNumElements())
486         return true;
487 
488       // If we read all of the bytes we needed from this element we're done.
489       uint64_t NextEltOffset = SL->getElementOffset(Index);
490 
491       if (BytesLeft <= NextEltOffset - CurEltOffset - ByteOffset)
492         return true;
493 
494       // Move to the next element of the struct.
495       CurPtr += NextEltOffset - CurEltOffset - ByteOffset;
496       BytesLeft -= NextEltOffset - CurEltOffset - ByteOffset;
497       ByteOffset = 0;
498       CurEltOffset = NextEltOffset;
499     }
500     // not reached.
501   }
502 
503   if (isa<ConstantArray>(C) || isa<ConstantVector>(C) ||
504       isa<ConstantDataSequential>(C)) {
505     uint64_t NumElts;
506     Type *EltTy;
507     if (auto *AT = dyn_cast<ArrayType>(C->getType())) {
508       NumElts = AT->getNumElements();
509       EltTy = AT->getElementType();
510     } else {
511       NumElts = cast<FixedVectorType>(C->getType())->getNumElements();
512       EltTy = cast<FixedVectorType>(C->getType())->getElementType();
513     }
514     uint64_t EltSize = DL.getTypeAllocSize(EltTy);
515     uint64_t Index = ByteOffset / EltSize;
516     uint64_t Offset = ByteOffset - Index * EltSize;
517 
518     for (; Index != NumElts; ++Index) {
519       if (!ReadDataFromGlobal(C->getAggregateElement(Index), Offset, CurPtr,
520                               BytesLeft, DL))
521         return false;
522 
523       uint64_t BytesWritten = EltSize - Offset;
524       assert(BytesWritten <= EltSize && "Not indexing into this element?");
525       if (BytesWritten >= BytesLeft)
526         return true;
527 
528       Offset = 0;
529       BytesLeft -= BytesWritten;
530       CurPtr += BytesWritten;
531     }
532     return true;
533   }
534 
535   if (auto *CE = dyn_cast<ConstantExpr>(C)) {
536     if (CE->getOpcode() == Instruction::IntToPtr &&
537         CE->getOperand(0)->getType() == DL.getIntPtrType(CE->getType())) {
538       return ReadDataFromGlobal(CE->getOperand(0), ByteOffset, CurPtr,
539                                 BytesLeft, DL);
540     }
541   }
542 
543   // Otherwise, unknown initializer type.
544   return false;
545 }
546 
547 Constant *FoldReinterpretLoadFromConstPtr(Constant *C, Type *LoadTy,
548                                           const DataLayout &DL) {
549   // Bail out early. Not expect to load from scalable global variable.
550   if (isa<ScalableVectorType>(LoadTy))
551     return nullptr;
552 
553   auto *PTy = cast<PointerType>(C->getType());
554   auto *IntType = dyn_cast<IntegerType>(LoadTy);
555 
556   // If this isn't an integer load we can't fold it directly.
557   if (!IntType) {
558     unsigned AS = PTy->getAddressSpace();
559 
560     // If this is a float/double load, we can try folding it as an int32/64 load
561     // and then bitcast the result.  This can be useful for union cases.  Note
562     // that address spaces don't matter here since we're not going to result in
563     // an actual new load.
564     Type *MapTy;
565     if (LoadTy->isHalfTy())
566       MapTy = Type::getInt16Ty(C->getContext());
567     else if (LoadTy->isFloatTy())
568       MapTy = Type::getInt32Ty(C->getContext());
569     else if (LoadTy->isDoubleTy())
570       MapTy = Type::getInt64Ty(C->getContext());
571     else if (LoadTy->isVectorTy()) {
572       MapTy = PointerType::getIntNTy(
573           C->getContext(), DL.getTypeSizeInBits(LoadTy).getFixedSize());
574     } else
575       return nullptr;
576 
577     C = FoldBitCast(C, MapTy->getPointerTo(AS), DL);
578     if (Constant *Res = FoldReinterpretLoadFromConstPtr(C, MapTy, DL)) {
579       if (Res->isNullValue() && !LoadTy->isX86_MMXTy() &&
580           !LoadTy->isX86_AMXTy())
581         // Materializing a zero can be done trivially without a bitcast
582         return Constant::getNullValue(LoadTy);
583       Type *CastTy = LoadTy->isPtrOrPtrVectorTy() ? DL.getIntPtrType(LoadTy) : LoadTy;
584       Res = FoldBitCast(Res, CastTy, DL);
585       if (LoadTy->isPtrOrPtrVectorTy()) {
586         // For vector of pointer, we needed to first convert to a vector of integer, then do vector inttoptr
587         if (Res->isNullValue() && !LoadTy->isX86_MMXTy() &&
588             !LoadTy->isX86_AMXTy())
589           return Constant::getNullValue(LoadTy);
590         if (DL.isNonIntegralPointerType(LoadTy->getScalarType()))
591           // Be careful not to replace a load of an addrspace value with an inttoptr here
592           return nullptr;
593         Res = ConstantExpr::getCast(Instruction::IntToPtr, Res, LoadTy);
594       }
595       return Res;
596     }
597     return nullptr;
598   }
599 
600   unsigned BytesLoaded = (IntType->getBitWidth() + 7) / 8;
601   if (BytesLoaded > 32 || BytesLoaded == 0)
602     return nullptr;
603 
604   GlobalValue *GVal;
605   APInt OffsetAI;
606   if (!IsConstantOffsetFromGlobal(C, GVal, OffsetAI, DL))
607     return nullptr;
608 
609   auto *GV = dyn_cast<GlobalVariable>(GVal);
610   if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
611       !GV->getInitializer()->getType()->isSized())
612     return nullptr;
613 
614   int64_t Offset = OffsetAI.getSExtValue();
615   int64_t InitializerSize =
616       DL.getTypeAllocSize(GV->getInitializer()->getType()).getFixedSize();
617 
618   // If we're not accessing anything in this constant, the result is undefined.
619   if (Offset <= -1 * static_cast<int64_t>(BytesLoaded))
620     return UndefValue::get(IntType);
621 
622   // If we're not accessing anything in this constant, the result is undefined.
623   if (Offset >= InitializerSize)
624     return UndefValue::get(IntType);
625 
626   unsigned char RawBytes[32] = {0};
627   unsigned char *CurPtr = RawBytes;
628   unsigned BytesLeft = BytesLoaded;
629 
630   // If we're loading off the beginning of the global, some bytes may be valid.
631   if (Offset < 0) {
632     CurPtr += -Offset;
633     BytesLeft += Offset;
634     Offset = 0;
635   }
636 
637   if (!ReadDataFromGlobal(GV->getInitializer(), Offset, CurPtr, BytesLeft, DL))
638     return nullptr;
639 
640   APInt ResultVal = APInt(IntType->getBitWidth(), 0);
641   if (DL.isLittleEndian()) {
642     ResultVal = RawBytes[BytesLoaded - 1];
643     for (unsigned i = 1; i != BytesLoaded; ++i) {
644       ResultVal <<= 8;
645       ResultVal |= RawBytes[BytesLoaded - 1 - i];
646     }
647   } else {
648     ResultVal = RawBytes[0];
649     for (unsigned i = 1; i != BytesLoaded; ++i) {
650       ResultVal <<= 8;
651       ResultVal |= RawBytes[i];
652     }
653   }
654 
655   return ConstantInt::get(IntType->getContext(), ResultVal);
656 }
657 
658 Constant *ConstantFoldLoadThroughBitcastExpr(ConstantExpr *CE, Type *DestTy,
659                                              const DataLayout &DL) {
660   auto *SrcPtr = CE->getOperand(0);
661   auto *SrcPtrTy = dyn_cast<PointerType>(SrcPtr->getType());
662   if (!SrcPtrTy)
663     return nullptr;
664   Type *SrcTy = SrcPtrTy->getPointerElementType();
665 
666   Constant *C = ConstantFoldLoadFromConstPtr(SrcPtr, SrcTy, DL);
667   if (!C)
668     return nullptr;
669 
670   return llvm::ConstantFoldLoadThroughBitcast(C, DestTy, DL);
671 }
672 
673 } // end anonymous namespace
674 
675 Constant *llvm::ConstantFoldLoadFromConstPtr(Constant *C, Type *Ty,
676                                              const DataLayout &DL) {
677   // First, try the easy cases:
678   if (auto *GV = dyn_cast<GlobalVariable>(C))
679     if (GV->isConstant() && GV->hasDefinitiveInitializer())
680       return GV->getInitializer();
681 
682   if (auto *GA = dyn_cast<GlobalAlias>(C))
683     if (GA->getAliasee() && !GA->isInterposable())
684       return ConstantFoldLoadFromConstPtr(GA->getAliasee(), Ty, DL);
685 
686   // If the loaded value isn't a constant expr, we can't handle it.
687   auto *CE = dyn_cast<ConstantExpr>(C);
688   if (!CE)
689     return nullptr;
690 
691   if (CE->getOpcode() == Instruction::GetElementPtr) {
692     if (auto *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
693       if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
694         if (Constant *V =
695              ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
696           return V;
697       }
698     }
699   }
700 
701   if (CE->getOpcode() == Instruction::BitCast)
702     if (Constant *LoadedC = ConstantFoldLoadThroughBitcastExpr(CE, Ty, DL))
703       return LoadedC;
704 
705   // Instead of loading constant c string, use corresponding integer value
706   // directly if string length is small enough.
707   StringRef Str;
708   if (getConstantStringInfo(CE, Str) && !Str.empty()) {
709     size_t StrLen = Str.size();
710     unsigned NumBits = Ty->getPrimitiveSizeInBits();
711     // Replace load with immediate integer if the result is an integer or fp
712     // value.
713     if ((NumBits >> 3) == StrLen + 1 && (NumBits & 7) == 0 &&
714         (isa<IntegerType>(Ty) || Ty->isFloatingPointTy())) {
715       APInt StrVal(NumBits, 0);
716       APInt SingleChar(NumBits, 0);
717       if (DL.isLittleEndian()) {
718         for (unsigned char C : reverse(Str.bytes())) {
719           SingleChar = static_cast<uint64_t>(C);
720           StrVal = (StrVal << 8) | SingleChar;
721         }
722       } else {
723         for (unsigned char C : Str.bytes()) {
724           SingleChar = static_cast<uint64_t>(C);
725           StrVal = (StrVal << 8) | SingleChar;
726         }
727         // Append NULL at the end.
728         SingleChar = 0;
729         StrVal = (StrVal << 8) | SingleChar;
730       }
731 
732       Constant *Res = ConstantInt::get(CE->getContext(), StrVal);
733       if (Ty->isFloatingPointTy())
734         Res = ConstantExpr::getBitCast(Res, Ty);
735       return Res;
736     }
737   }
738 
739   // If this load comes from anywhere in a constant global, and if the global
740   // is all undef or zero, we know what it loads.
741   if (auto *GV = dyn_cast<GlobalVariable>(getUnderlyingObject(CE))) {
742     if (GV->isConstant() && GV->hasDefinitiveInitializer()) {
743       if (GV->getInitializer()->isNullValue())
744         return Constant::getNullValue(Ty);
745       if (isa<UndefValue>(GV->getInitializer()))
746         return UndefValue::get(Ty);
747     }
748   }
749 
750   // Try hard to fold loads from bitcasted strange and non-type-safe things.
751   return FoldReinterpretLoadFromConstPtr(CE, Ty, DL);
752 }
753 
754 namespace {
755 
756 Constant *ConstantFoldLoadInst(const LoadInst *LI, const DataLayout &DL) {
757   if (LI->isVolatile()) return nullptr;
758 
759   if (auto *C = dyn_cast<Constant>(LI->getOperand(0)))
760     return ConstantFoldLoadFromConstPtr(C, LI->getType(), DL);
761 
762   return nullptr;
763 }
764 
765 /// One of Op0/Op1 is a constant expression.
766 /// Attempt to symbolically evaluate the result of a binary operator merging
767 /// these together.  If target data info is available, it is provided as DL,
768 /// otherwise DL is null.
769 Constant *SymbolicallyEvaluateBinop(unsigned Opc, Constant *Op0, Constant *Op1,
770                                     const DataLayout &DL) {
771   // SROA
772 
773   // Fold (and 0xffffffff00000000, (shl x, 32)) -> shl.
774   // Fold (lshr (or X, Y), 32) -> (lshr [X/Y], 32) if one doesn't contribute
775   // bits.
776 
777   if (Opc == Instruction::And) {
778     KnownBits Known0 = computeKnownBits(Op0, DL);
779     KnownBits Known1 = computeKnownBits(Op1, DL);
780     if ((Known1.One | Known0.Zero).isAllOnesValue()) {
781       // All the bits of Op0 that the 'and' could be masking are already zero.
782       return Op0;
783     }
784     if ((Known0.One | Known1.Zero).isAllOnesValue()) {
785       // All the bits of Op1 that the 'and' could be masking are already zero.
786       return Op1;
787     }
788 
789     Known0 &= Known1;
790     if (Known0.isConstant())
791       return ConstantInt::get(Op0->getType(), Known0.getConstant());
792   }
793 
794   // If the constant expr is something like &A[123] - &A[4].f, fold this into a
795   // constant.  This happens frequently when iterating over a global array.
796   if (Opc == Instruction::Sub) {
797     GlobalValue *GV1, *GV2;
798     APInt Offs1, Offs2;
799 
800     if (IsConstantOffsetFromGlobal(Op0, GV1, Offs1, DL))
801       if (IsConstantOffsetFromGlobal(Op1, GV2, Offs2, DL) && GV1 == GV2) {
802         unsigned OpSize = DL.getTypeSizeInBits(Op0->getType());
803 
804         // (&GV+C1) - (&GV+C2) -> C1-C2, pointer arithmetic cannot overflow.
805         // PtrToInt may change the bitwidth so we have convert to the right size
806         // first.
807         return ConstantInt::get(Op0->getType(), Offs1.zextOrTrunc(OpSize) -
808                                                 Offs2.zextOrTrunc(OpSize));
809       }
810   }
811 
812   return nullptr;
813 }
814 
815 /// If array indices are not pointer-sized integers, explicitly cast them so
816 /// that they aren't implicitly casted by the getelementptr.
817 Constant *CastGEPIndices(Type *SrcElemTy, ArrayRef<Constant *> Ops,
818                          Type *ResultTy, Optional<unsigned> InRangeIndex,
819                          const DataLayout &DL, const TargetLibraryInfo *TLI) {
820   Type *IntIdxTy = DL.getIndexType(ResultTy);
821   Type *IntIdxScalarTy = IntIdxTy->getScalarType();
822 
823   bool Any = false;
824   SmallVector<Constant*, 32> NewIdxs;
825   for (unsigned i = 1, e = Ops.size(); i != e; ++i) {
826     if ((i == 1 ||
827          !isa<StructType>(GetElementPtrInst::getIndexedType(
828              SrcElemTy, Ops.slice(1, i - 1)))) &&
829         Ops[i]->getType()->getScalarType() != IntIdxScalarTy) {
830       Any = true;
831       Type *NewType = Ops[i]->getType()->isVectorTy()
832                           ? IntIdxTy
833                           : IntIdxScalarTy;
834       NewIdxs.push_back(ConstantExpr::getCast(CastInst::getCastOpcode(Ops[i],
835                                                                       true,
836                                                                       NewType,
837                                                                       true),
838                                               Ops[i], NewType));
839     } else
840       NewIdxs.push_back(Ops[i]);
841   }
842 
843   if (!Any)
844     return nullptr;
845 
846   Constant *C = ConstantExpr::getGetElementPtr(
847       SrcElemTy, Ops[0], NewIdxs, /*InBounds=*/false, InRangeIndex);
848   return ConstantFoldConstant(C, DL, TLI);
849 }
850 
851 /// Strip the pointer casts, but preserve the address space information.
852 Constant *StripPtrCastKeepAS(Constant *Ptr, Type *&ElemTy) {
853   assert(Ptr->getType()->isPointerTy() && "Not a pointer type");
854   auto *OldPtrTy = cast<PointerType>(Ptr->getType());
855   Ptr = cast<Constant>(Ptr->stripPointerCasts());
856   auto *NewPtrTy = cast<PointerType>(Ptr->getType());
857 
858   ElemTy = NewPtrTy->getPointerElementType();
859 
860   // Preserve the address space number of the pointer.
861   if (NewPtrTy->getAddressSpace() != OldPtrTy->getAddressSpace()) {
862     NewPtrTy = ElemTy->getPointerTo(OldPtrTy->getAddressSpace());
863     Ptr = ConstantExpr::getPointerCast(Ptr, NewPtrTy);
864   }
865   return Ptr;
866 }
867 
868 /// If we can symbolically evaluate the GEP constant expression, do so.
869 Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
870                                   ArrayRef<Constant *> Ops,
871                                   const DataLayout &DL,
872                                   const TargetLibraryInfo *TLI) {
873   const GEPOperator *InnermostGEP = GEP;
874   bool InBounds = GEP->isInBounds();
875 
876   Type *SrcElemTy = GEP->getSourceElementType();
877   Type *ResElemTy = GEP->getResultElementType();
878   Type *ResTy = GEP->getType();
879   if (!SrcElemTy->isSized() || isa<ScalableVectorType>(SrcElemTy))
880     return nullptr;
881 
882   if (Constant *C = CastGEPIndices(SrcElemTy, Ops, ResTy,
883                                    GEP->getInRangeIndex(), DL, TLI))
884     return C;
885 
886   Constant *Ptr = Ops[0];
887   if (!Ptr->getType()->isPointerTy())
888     return nullptr;
889 
890   Type *IntIdxTy = DL.getIndexType(Ptr->getType());
891 
892   // If this is a constant expr gep that is effectively computing an
893   // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12'
894   for (unsigned i = 1, e = Ops.size(); i != e; ++i)
895       if (!isa<ConstantInt>(Ops[i])) {
896 
897         // If this is "gep i8* Ptr, (sub 0, V)", fold this as:
898         // "inttoptr (sub (ptrtoint Ptr), V)"
899         if (Ops.size() == 2 && ResElemTy->isIntegerTy(8)) {
900           auto *CE = dyn_cast<ConstantExpr>(Ops[1]);
901           assert((!CE || CE->getType() == IntIdxTy) &&
902                  "CastGEPIndices didn't canonicalize index types!");
903           if (CE && CE->getOpcode() == Instruction::Sub &&
904               CE->getOperand(0)->isNullValue()) {
905             Constant *Res = ConstantExpr::getPtrToInt(Ptr, CE->getType());
906             Res = ConstantExpr::getSub(Res, CE->getOperand(1));
907             Res = ConstantExpr::getIntToPtr(Res, ResTy);
908             return ConstantFoldConstant(Res, DL, TLI);
909           }
910         }
911         return nullptr;
912       }
913 
914   unsigned BitWidth = DL.getTypeSizeInBits(IntIdxTy);
915   APInt Offset =
916       APInt(BitWidth,
917             DL.getIndexedOffsetInType(
918                 SrcElemTy,
919                 makeArrayRef((Value * const *)Ops.data() + 1, Ops.size() - 1)));
920   Ptr = StripPtrCastKeepAS(Ptr, SrcElemTy);
921 
922   // If this is a GEP of a GEP, fold it all into a single GEP.
923   while (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
924     InnermostGEP = GEP;
925     InBounds &= GEP->isInBounds();
926 
927     SmallVector<Value *, 4> NestedOps(GEP->op_begin() + 1, GEP->op_end());
928 
929     // Do not try the incorporate the sub-GEP if some index is not a number.
930     bool AllConstantInt = true;
931     for (Value *NestedOp : NestedOps)
932       if (!isa<ConstantInt>(NestedOp)) {
933         AllConstantInt = false;
934         break;
935       }
936     if (!AllConstantInt)
937       break;
938 
939     Ptr = cast<Constant>(GEP->getOperand(0));
940     SrcElemTy = GEP->getSourceElementType();
941     Offset += APInt(BitWidth, DL.getIndexedOffsetInType(SrcElemTy, NestedOps));
942     Ptr = StripPtrCastKeepAS(Ptr, SrcElemTy);
943   }
944 
945   // If the base value for this address is a literal integer value, fold the
946   // getelementptr to the resulting integer value casted to the pointer type.
947   APInt BasePtr(BitWidth, 0);
948   if (auto *CE = dyn_cast<ConstantExpr>(Ptr)) {
949     if (CE->getOpcode() == Instruction::IntToPtr) {
950       if (auto *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
951         BasePtr = Base->getValue().zextOrTrunc(BitWidth);
952     }
953   }
954 
955   auto *PTy = cast<PointerType>(Ptr->getType());
956   if ((Ptr->isNullValue() || BasePtr != 0) &&
957       !DL.isNonIntegralPointerType(PTy)) {
958     Constant *C = ConstantInt::get(Ptr->getContext(), Offset + BasePtr);
959     return ConstantExpr::getIntToPtr(C, ResTy);
960   }
961 
962   // Otherwise form a regular getelementptr. Recompute the indices so that
963   // we eliminate over-indexing of the notional static type array bounds.
964   // This makes it easy to determine if the getelementptr is "inbounds".
965   // Also, this helps GlobalOpt do SROA on GlobalVariables.
966   Type *Ty = PTy;
967   SmallVector<Constant *, 32> NewIdxs;
968 
969   do {
970     if (!Ty->isStructTy()) {
971       if (Ty->isPointerTy()) {
972         // The only pointer indexing we'll do is on the first index of the GEP.
973         if (!NewIdxs.empty())
974           break;
975 
976         Ty = SrcElemTy;
977 
978         // Only handle pointers to sized types, not pointers to functions.
979         if (!Ty->isSized())
980           return nullptr;
981       } else {
982         Type *NextTy = GetElementPtrInst::getTypeAtIndex(Ty, (uint64_t)0);
983         if (!NextTy)
984           break;
985         Ty = NextTy;
986       }
987 
988       // Determine which element of the array the offset points into.
989       APInt ElemSize(BitWidth, DL.getTypeAllocSize(Ty));
990       if (ElemSize == 0) {
991         // The element size is 0. This may be [0 x Ty]*, so just use a zero
992         // index for this level and proceed to the next level to see if it can
993         // accommodate the offset.
994         NewIdxs.push_back(ConstantInt::get(IntIdxTy, 0));
995       } else {
996         // The element size is non-zero divide the offset by the element
997         // size (rounding down), to compute the index at this level.
998         bool Overflow;
999         APInt NewIdx = Offset.sdiv_ov(ElemSize, Overflow);
1000         if (Overflow)
1001           break;
1002         Offset -= NewIdx * ElemSize;
1003         NewIdxs.push_back(ConstantInt::get(IntIdxTy, NewIdx));
1004       }
1005     } else {
1006       auto *STy = cast<StructType>(Ty);
1007       // If we end up with an offset that isn't valid for this struct type, we
1008       // can't re-form this GEP in a regular form, so bail out. The pointer
1009       // operand likely went through casts that are necessary to make the GEP
1010       // sensible.
1011       const StructLayout &SL = *DL.getStructLayout(STy);
1012       if (Offset.isNegative() || Offset.uge(SL.getSizeInBytes()))
1013         break;
1014 
1015       // Determine which field of the struct the offset points into. The
1016       // getZExtValue is fine as we've already ensured that the offset is
1017       // within the range representable by the StructLayout API.
1018       unsigned ElIdx = SL.getElementContainingOffset(Offset.getZExtValue());
1019       NewIdxs.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
1020                                          ElIdx));
1021       Offset -= APInt(BitWidth, SL.getElementOffset(ElIdx));
1022       Ty = STy->getTypeAtIndex(ElIdx);
1023     }
1024   } while (Ty != ResElemTy);
1025 
1026   // If we haven't used up the entire offset by descending the static
1027   // type, then the offset is pointing into the middle of an indivisible
1028   // member, so we can't simplify it.
1029   if (Offset != 0)
1030     return nullptr;
1031 
1032   // Preserve the inrange index from the innermost GEP if possible. We must
1033   // have calculated the same indices up to and including the inrange index.
1034   Optional<unsigned> InRangeIndex;
1035   if (Optional<unsigned> LastIRIndex = InnermostGEP->getInRangeIndex())
1036     if (SrcElemTy == InnermostGEP->getSourceElementType() &&
1037         NewIdxs.size() > *LastIRIndex) {
1038       InRangeIndex = LastIRIndex;
1039       for (unsigned I = 0; I <= *LastIRIndex; ++I)
1040         if (NewIdxs[I] != InnermostGEP->getOperand(I + 1))
1041           return nullptr;
1042     }
1043 
1044   // Create a GEP.
1045   Constant *C = ConstantExpr::getGetElementPtr(SrcElemTy, Ptr, NewIdxs,
1046                                                InBounds, InRangeIndex);
1047   assert(C->getType()->getPointerElementType() == Ty &&
1048          "Computed GetElementPtr has unexpected type!");
1049 
1050   // If we ended up indexing a member with a type that doesn't match
1051   // the type of what the original indices indexed, add a cast.
1052   if (Ty != ResElemTy)
1053     C = FoldBitCast(C, ResTy, DL);
1054 
1055   return C;
1056 }
1057 
1058 /// Attempt to constant fold an instruction with the
1059 /// specified opcode and operands.  If successful, the constant result is
1060 /// returned, if not, null is returned.  Note that this function can fail when
1061 /// attempting to fold instructions like loads and stores, which have no
1062 /// constant expression form.
1063 Constant *ConstantFoldInstOperandsImpl(const Value *InstOrCE, unsigned Opcode,
1064                                        ArrayRef<Constant *> Ops,
1065                                        const DataLayout &DL,
1066                                        const TargetLibraryInfo *TLI) {
1067   Type *DestTy = InstOrCE->getType();
1068 
1069   if (Instruction::isUnaryOp(Opcode))
1070     return ConstantFoldUnaryOpOperand(Opcode, Ops[0], DL);
1071 
1072   if (Instruction::isBinaryOp(Opcode))
1073     return ConstantFoldBinaryOpOperands(Opcode, Ops[0], Ops[1], DL);
1074 
1075   if (Instruction::isCast(Opcode))
1076     return ConstantFoldCastOperand(Opcode, Ops[0], DestTy, DL);
1077 
1078   if (auto *GEP = dyn_cast<GEPOperator>(InstOrCE)) {
1079     if (Constant *C = SymbolicallyEvaluateGEP(GEP, Ops, DL, TLI))
1080       return C;
1081 
1082     return ConstantExpr::getGetElementPtr(GEP->getSourceElementType(), Ops[0],
1083                                           Ops.slice(1), GEP->isInBounds(),
1084                                           GEP->getInRangeIndex());
1085   }
1086 
1087   if (auto *CE = dyn_cast<ConstantExpr>(InstOrCE))
1088     return CE->getWithOperands(Ops);
1089 
1090   switch (Opcode) {
1091   default: return nullptr;
1092   case Instruction::ICmp:
1093   case Instruction::FCmp: llvm_unreachable("Invalid for compares");
1094   case Instruction::Freeze:
1095     return isGuaranteedNotToBeUndefOrPoison(Ops[0]) ? Ops[0] : nullptr;
1096   case Instruction::Call:
1097     if (auto *F = dyn_cast<Function>(Ops.back())) {
1098       const auto *Call = cast<CallBase>(InstOrCE);
1099       if (canConstantFoldCallTo(Call, F))
1100         return ConstantFoldCall(Call, F, Ops.slice(0, Ops.size() - 1), TLI);
1101     }
1102     return nullptr;
1103   case Instruction::Select:
1104     return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
1105   case Instruction::ExtractElement:
1106     return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
1107   case Instruction::ExtractValue:
1108     return ConstantExpr::getExtractValue(
1109         Ops[0], cast<ExtractValueInst>(InstOrCE)->getIndices());
1110   case Instruction::InsertElement:
1111     return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
1112   case Instruction::ShuffleVector:
1113     return ConstantExpr::getShuffleVector(
1114         Ops[0], Ops[1], cast<ShuffleVectorInst>(InstOrCE)->getShuffleMask());
1115   }
1116 }
1117 
1118 } // end anonymous namespace
1119 
1120 //===----------------------------------------------------------------------===//
1121 // Constant Folding public APIs
1122 //===----------------------------------------------------------------------===//
1123 
1124 namespace {
1125 
1126 Constant *
1127 ConstantFoldConstantImpl(const Constant *C, const DataLayout &DL,
1128                          const TargetLibraryInfo *TLI,
1129                          SmallDenseMap<Constant *, Constant *> &FoldedOps) {
1130   if (!isa<ConstantVector>(C) && !isa<ConstantExpr>(C))
1131     return const_cast<Constant *>(C);
1132 
1133   SmallVector<Constant *, 8> Ops;
1134   for (const Use &OldU : C->operands()) {
1135     Constant *OldC = cast<Constant>(&OldU);
1136     Constant *NewC = OldC;
1137     // Recursively fold the ConstantExpr's operands. If we have already folded
1138     // a ConstantExpr, we don't have to process it again.
1139     if (isa<ConstantVector>(OldC) || isa<ConstantExpr>(OldC)) {
1140       auto It = FoldedOps.find(OldC);
1141       if (It == FoldedOps.end()) {
1142         NewC = ConstantFoldConstantImpl(OldC, DL, TLI, FoldedOps);
1143         FoldedOps.insert({OldC, NewC});
1144       } else {
1145         NewC = It->second;
1146       }
1147     }
1148     Ops.push_back(NewC);
1149   }
1150 
1151   if (auto *CE = dyn_cast<ConstantExpr>(C)) {
1152     if (CE->isCompare())
1153       return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
1154                                              DL, TLI);
1155 
1156     return ConstantFoldInstOperandsImpl(CE, CE->getOpcode(), Ops, DL, TLI);
1157   }
1158 
1159   assert(isa<ConstantVector>(C));
1160   return ConstantVector::get(Ops);
1161 }
1162 
1163 } // end anonymous namespace
1164 
1165 Constant *llvm::ConstantFoldInstruction(Instruction *I, const DataLayout &DL,
1166                                         const TargetLibraryInfo *TLI) {
1167   // Handle PHI nodes quickly here...
1168   if (auto *PN = dyn_cast<PHINode>(I)) {
1169     Constant *CommonValue = nullptr;
1170 
1171     SmallDenseMap<Constant *, Constant *> FoldedOps;
1172     for (Value *Incoming : PN->incoming_values()) {
1173       // If the incoming value is undef then skip it.  Note that while we could
1174       // skip the value if it is equal to the phi node itself we choose not to
1175       // because that would break the rule that constant folding only applies if
1176       // all operands are constants.
1177       if (isa<UndefValue>(Incoming))
1178         continue;
1179       // If the incoming value is not a constant, then give up.
1180       auto *C = dyn_cast<Constant>(Incoming);
1181       if (!C)
1182         return nullptr;
1183       // Fold the PHI's operands.
1184       C = ConstantFoldConstantImpl(C, DL, TLI, FoldedOps);
1185       // If the incoming value is a different constant to
1186       // the one we saw previously, then give up.
1187       if (CommonValue && C != CommonValue)
1188         return nullptr;
1189       CommonValue = C;
1190     }
1191 
1192     // If we reach here, all incoming values are the same constant or undef.
1193     return CommonValue ? CommonValue : UndefValue::get(PN->getType());
1194   }
1195 
1196   // Scan the operand list, checking to see if they are all constants, if so,
1197   // hand off to ConstantFoldInstOperandsImpl.
1198   if (!all_of(I->operands(), [](Use &U) { return isa<Constant>(U); }))
1199     return nullptr;
1200 
1201   SmallDenseMap<Constant *, Constant *> FoldedOps;
1202   SmallVector<Constant *, 8> Ops;
1203   for (const Use &OpU : I->operands()) {
1204     auto *Op = cast<Constant>(&OpU);
1205     // Fold the Instruction's operands.
1206     Op = ConstantFoldConstantImpl(Op, DL, TLI, FoldedOps);
1207     Ops.push_back(Op);
1208   }
1209 
1210   if (const auto *CI = dyn_cast<CmpInst>(I))
1211     return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
1212                                            DL, TLI);
1213 
1214   if (const auto *LI = dyn_cast<LoadInst>(I))
1215     return ConstantFoldLoadInst(LI, DL);
1216 
1217   if (auto *IVI = dyn_cast<InsertValueInst>(I)) {
1218     return ConstantExpr::getInsertValue(
1219                                 cast<Constant>(IVI->getAggregateOperand()),
1220                                 cast<Constant>(IVI->getInsertedValueOperand()),
1221                                 IVI->getIndices());
1222   }
1223 
1224   if (auto *EVI = dyn_cast<ExtractValueInst>(I)) {
1225     return ConstantExpr::getExtractValue(
1226                                     cast<Constant>(EVI->getAggregateOperand()),
1227                                     EVI->getIndices());
1228   }
1229 
1230   return ConstantFoldInstOperands(I, Ops, DL, TLI);
1231 }
1232 
1233 Constant *llvm::ConstantFoldConstant(const Constant *C, const DataLayout &DL,
1234                                      const TargetLibraryInfo *TLI) {
1235   SmallDenseMap<Constant *, Constant *> FoldedOps;
1236   return ConstantFoldConstantImpl(C, DL, TLI, FoldedOps);
1237 }
1238 
1239 Constant *llvm::ConstantFoldInstOperands(Instruction *I,
1240                                          ArrayRef<Constant *> Ops,
1241                                          const DataLayout &DL,
1242                                          const TargetLibraryInfo *TLI) {
1243   return ConstantFoldInstOperandsImpl(I, I->getOpcode(), Ops, DL, TLI);
1244 }
1245 
1246 Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate,
1247                                                 Constant *Ops0, Constant *Ops1,
1248                                                 const DataLayout &DL,
1249                                                 const TargetLibraryInfo *TLI) {
1250   // fold: icmp (inttoptr x), null         -> icmp x, 0
1251   // fold: icmp null, (inttoptr x)         -> icmp 0, x
1252   // fold: icmp (ptrtoint x), 0            -> icmp x, null
1253   // fold: icmp 0, (ptrtoint x)            -> icmp null, x
1254   // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y
1255   // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y
1256   //
1257   // FIXME: The following comment is out of data and the DataLayout is here now.
1258   // ConstantExpr::getCompare cannot do this, because it doesn't have DL
1259   // around to know if bit truncation is happening.
1260   if (auto *CE0 = dyn_cast<ConstantExpr>(Ops0)) {
1261     if (Ops1->isNullValue()) {
1262       if (CE0->getOpcode() == Instruction::IntToPtr) {
1263         Type *IntPtrTy = DL.getIntPtrType(CE0->getType());
1264         // Convert the integer value to the right size to ensure we get the
1265         // proper extension or truncation.
1266         Constant *C = ConstantExpr::getIntegerCast(CE0->getOperand(0),
1267                                                    IntPtrTy, false);
1268         Constant *Null = Constant::getNullValue(C->getType());
1269         return ConstantFoldCompareInstOperands(Predicate, C, Null, DL, TLI);
1270       }
1271 
1272       // Only do this transformation if the int is intptrty in size, otherwise
1273       // there is a truncation or extension that we aren't modeling.
1274       if (CE0->getOpcode() == Instruction::PtrToInt) {
1275         Type *IntPtrTy = DL.getIntPtrType(CE0->getOperand(0)->getType());
1276         if (CE0->getType() == IntPtrTy) {
1277           Constant *C = CE0->getOperand(0);
1278           Constant *Null = Constant::getNullValue(C->getType());
1279           return ConstantFoldCompareInstOperands(Predicate, C, Null, DL, TLI);
1280         }
1281       }
1282     }
1283 
1284     if (auto *CE1 = dyn_cast<ConstantExpr>(Ops1)) {
1285       if (CE0->getOpcode() == CE1->getOpcode()) {
1286         if (CE0->getOpcode() == Instruction::IntToPtr) {
1287           Type *IntPtrTy = DL.getIntPtrType(CE0->getType());
1288 
1289           // Convert the integer value to the right size to ensure we get the
1290           // proper extension or truncation.
1291           Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0),
1292                                                       IntPtrTy, false);
1293           Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0),
1294                                                       IntPtrTy, false);
1295           return ConstantFoldCompareInstOperands(Predicate, C0, C1, DL, TLI);
1296         }
1297 
1298         // Only do this transformation if the int is intptrty in size, otherwise
1299         // there is a truncation or extension that we aren't modeling.
1300         if (CE0->getOpcode() == Instruction::PtrToInt) {
1301           Type *IntPtrTy = DL.getIntPtrType(CE0->getOperand(0)->getType());
1302           if (CE0->getType() == IntPtrTy &&
1303               CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType()) {
1304             return ConstantFoldCompareInstOperands(
1305                 Predicate, CE0->getOperand(0), CE1->getOperand(0), DL, TLI);
1306           }
1307         }
1308       }
1309     }
1310 
1311     // icmp eq (or x, y), 0 -> (icmp eq x, 0) & (icmp eq y, 0)
1312     // icmp ne (or x, y), 0 -> (icmp ne x, 0) | (icmp ne y, 0)
1313     if ((Predicate == ICmpInst::ICMP_EQ || Predicate == ICmpInst::ICMP_NE) &&
1314         CE0->getOpcode() == Instruction::Or && Ops1->isNullValue()) {
1315       Constant *LHS = ConstantFoldCompareInstOperands(
1316           Predicate, CE0->getOperand(0), Ops1, DL, TLI);
1317       Constant *RHS = ConstantFoldCompareInstOperands(
1318           Predicate, CE0->getOperand(1), Ops1, DL, TLI);
1319       unsigned OpC =
1320         Predicate == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
1321       return ConstantFoldBinaryOpOperands(OpC, LHS, RHS, DL);
1322     }
1323   } else if (isa<ConstantExpr>(Ops1)) {
1324     // If RHS is a constant expression, but the left side isn't, swap the
1325     // operands and try again.
1326     Predicate = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)Predicate);
1327     return ConstantFoldCompareInstOperands(Predicate, Ops1, Ops0, DL, TLI);
1328   }
1329 
1330   return ConstantExpr::getCompare(Predicate, Ops0, Ops1);
1331 }
1332 
1333 Constant *llvm::ConstantFoldUnaryOpOperand(unsigned Opcode, Constant *Op,
1334                                            const DataLayout &DL) {
1335   assert(Instruction::isUnaryOp(Opcode));
1336 
1337   return ConstantExpr::get(Opcode, Op);
1338 }
1339 
1340 Constant *llvm::ConstantFoldBinaryOpOperands(unsigned Opcode, Constant *LHS,
1341                                              Constant *RHS,
1342                                              const DataLayout &DL) {
1343   assert(Instruction::isBinaryOp(Opcode));
1344   if (isa<ConstantExpr>(LHS) || isa<ConstantExpr>(RHS))
1345     if (Constant *C = SymbolicallyEvaluateBinop(Opcode, LHS, RHS, DL))
1346       return C;
1347 
1348   return ConstantExpr::get(Opcode, LHS, RHS);
1349 }
1350 
1351 Constant *llvm::ConstantFoldCastOperand(unsigned Opcode, Constant *C,
1352                                         Type *DestTy, const DataLayout &DL) {
1353   assert(Instruction::isCast(Opcode));
1354   switch (Opcode) {
1355   default:
1356     llvm_unreachable("Missing case");
1357   case Instruction::PtrToInt:
1358     // If the input is a inttoptr, eliminate the pair.  This requires knowing
1359     // the width of a pointer, so it can't be done in ConstantExpr::getCast.
1360     if (auto *CE = dyn_cast<ConstantExpr>(C)) {
1361       if (CE->getOpcode() == Instruction::IntToPtr) {
1362         Constant *Input = CE->getOperand(0);
1363         unsigned InWidth = Input->getType()->getScalarSizeInBits();
1364         unsigned PtrWidth = DL.getPointerTypeSizeInBits(CE->getType());
1365         if (PtrWidth < InWidth) {
1366           Constant *Mask =
1367             ConstantInt::get(CE->getContext(),
1368                              APInt::getLowBitsSet(InWidth, PtrWidth));
1369           Input = ConstantExpr::getAnd(Input, Mask);
1370         }
1371         // Do a zext or trunc to get to the dest size.
1372         return ConstantExpr::getIntegerCast(Input, DestTy, false);
1373       }
1374     }
1375     return ConstantExpr::getCast(Opcode, C, DestTy);
1376   case Instruction::IntToPtr:
1377     // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
1378     // the int size is >= the ptr size and the address spaces are the same.
1379     // This requires knowing the width of a pointer, so it can't be done in
1380     // ConstantExpr::getCast.
1381     if (auto *CE = dyn_cast<ConstantExpr>(C)) {
1382       if (CE->getOpcode() == Instruction::PtrToInt) {
1383         Constant *SrcPtr = CE->getOperand(0);
1384         unsigned SrcPtrSize = DL.getPointerTypeSizeInBits(SrcPtr->getType());
1385         unsigned MidIntSize = CE->getType()->getScalarSizeInBits();
1386 
1387         if (MidIntSize >= SrcPtrSize) {
1388           unsigned SrcAS = SrcPtr->getType()->getPointerAddressSpace();
1389           if (SrcAS == DestTy->getPointerAddressSpace())
1390             return FoldBitCast(CE->getOperand(0), DestTy, DL);
1391         }
1392       }
1393     }
1394 
1395     return ConstantExpr::getCast(Opcode, C, DestTy);
1396   case Instruction::Trunc:
1397   case Instruction::ZExt:
1398   case Instruction::SExt:
1399   case Instruction::FPTrunc:
1400   case Instruction::FPExt:
1401   case Instruction::UIToFP:
1402   case Instruction::SIToFP:
1403   case Instruction::FPToUI:
1404   case Instruction::FPToSI:
1405   case Instruction::AddrSpaceCast:
1406       return ConstantExpr::getCast(Opcode, C, DestTy);
1407   case Instruction::BitCast:
1408     return FoldBitCast(C, DestTy, DL);
1409   }
1410 }
1411 
1412 Constant *llvm::ConstantFoldLoadThroughGEPConstantExpr(Constant *C,
1413                                                        ConstantExpr *CE) {
1414   if (!CE->getOperand(1)->isNullValue())
1415     return nullptr;  // Do not allow stepping over the value!
1416 
1417   // Loop over all of the operands, tracking down which value we are
1418   // addressing.
1419   for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i) {
1420     C = C->getAggregateElement(CE->getOperand(i));
1421     if (!C)
1422       return nullptr;
1423   }
1424   return C;
1425 }
1426 
1427 Constant *
1428 llvm::ConstantFoldLoadThroughGEPIndices(Constant *C,
1429                                         ArrayRef<Constant *> Indices) {
1430   // Loop over all of the operands, tracking down which value we are
1431   // addressing.
1432   for (Constant *Index : Indices) {
1433     C = C->getAggregateElement(Index);
1434     if (!C)
1435       return nullptr;
1436   }
1437   return C;
1438 }
1439 
1440 //===----------------------------------------------------------------------===//
1441 //  Constant Folding for Calls
1442 //
1443 
1444 bool llvm::canConstantFoldCallTo(const CallBase *Call, const Function *F) {
1445   if (Call->isNoBuiltin())
1446     return false;
1447   switch (F->getIntrinsicID()) {
1448   // Operations that do not operate floating-point numbers and do not depend on
1449   // FP environment can be folded even in strictfp functions.
1450   case Intrinsic::bswap:
1451   case Intrinsic::ctpop:
1452   case Intrinsic::ctlz:
1453   case Intrinsic::cttz:
1454   case Intrinsic::fshl:
1455   case Intrinsic::fshr:
1456   case Intrinsic::launder_invariant_group:
1457   case Intrinsic::strip_invariant_group:
1458   case Intrinsic::masked_load:
1459   case Intrinsic::get_active_lane_mask:
1460   case Intrinsic::abs:
1461   case Intrinsic::smax:
1462   case Intrinsic::smin:
1463   case Intrinsic::umax:
1464   case Intrinsic::umin:
1465   case Intrinsic::sadd_with_overflow:
1466   case Intrinsic::uadd_with_overflow:
1467   case Intrinsic::ssub_with_overflow:
1468   case Intrinsic::usub_with_overflow:
1469   case Intrinsic::smul_with_overflow:
1470   case Intrinsic::umul_with_overflow:
1471   case Intrinsic::sadd_sat:
1472   case Intrinsic::uadd_sat:
1473   case Intrinsic::ssub_sat:
1474   case Intrinsic::usub_sat:
1475   case Intrinsic::smul_fix:
1476   case Intrinsic::smul_fix_sat:
1477   case Intrinsic::bitreverse:
1478   case Intrinsic::is_constant:
1479   case Intrinsic::vector_reduce_add:
1480   case Intrinsic::vector_reduce_mul:
1481   case Intrinsic::vector_reduce_and:
1482   case Intrinsic::vector_reduce_or:
1483   case Intrinsic::vector_reduce_xor:
1484   case Intrinsic::vector_reduce_smin:
1485   case Intrinsic::vector_reduce_smax:
1486   case Intrinsic::vector_reduce_umin:
1487   case Intrinsic::vector_reduce_umax:
1488   // Target intrinsics
1489   case Intrinsic::arm_mve_vctp8:
1490   case Intrinsic::arm_mve_vctp16:
1491   case Intrinsic::arm_mve_vctp32:
1492   case Intrinsic::arm_mve_vctp64:
1493   // WebAssembly float semantics are always known
1494   case Intrinsic::wasm_trunc_signed:
1495   case Intrinsic::wasm_trunc_unsigned:
1496   case Intrinsic::wasm_trunc_saturate_signed:
1497   case Intrinsic::wasm_trunc_saturate_unsigned:
1498     return true;
1499 
1500   // Floating point operations cannot be folded in strictfp functions in
1501   // general case. They can be folded if FP environment is known to compiler.
1502   case Intrinsic::minnum:
1503   case Intrinsic::maxnum:
1504   case Intrinsic::minimum:
1505   case Intrinsic::maximum:
1506   case Intrinsic::log:
1507   case Intrinsic::log2:
1508   case Intrinsic::log10:
1509   case Intrinsic::exp:
1510   case Intrinsic::exp2:
1511   case Intrinsic::sqrt:
1512   case Intrinsic::sin:
1513   case Intrinsic::cos:
1514   case Intrinsic::pow:
1515   case Intrinsic::powi:
1516   case Intrinsic::fma:
1517   case Intrinsic::fmuladd:
1518   case Intrinsic::fptoui_sat:
1519   case Intrinsic::fptosi_sat:
1520   case Intrinsic::convert_from_fp16:
1521   case Intrinsic::convert_to_fp16:
1522   case Intrinsic::amdgcn_cos:
1523   case Intrinsic::amdgcn_cubeid:
1524   case Intrinsic::amdgcn_cubema:
1525   case Intrinsic::amdgcn_cubesc:
1526   case Intrinsic::amdgcn_cubetc:
1527   case Intrinsic::amdgcn_fmul_legacy:
1528   case Intrinsic::amdgcn_fma_legacy:
1529   case Intrinsic::amdgcn_fract:
1530   case Intrinsic::amdgcn_ldexp:
1531   case Intrinsic::amdgcn_sin:
1532   // The intrinsics below depend on rounding mode in MXCSR.
1533   case Intrinsic::x86_sse_cvtss2si:
1534   case Intrinsic::x86_sse_cvtss2si64:
1535   case Intrinsic::x86_sse_cvttss2si:
1536   case Intrinsic::x86_sse_cvttss2si64:
1537   case Intrinsic::x86_sse2_cvtsd2si:
1538   case Intrinsic::x86_sse2_cvtsd2si64:
1539   case Intrinsic::x86_sse2_cvttsd2si:
1540   case Intrinsic::x86_sse2_cvttsd2si64:
1541   case Intrinsic::x86_avx512_vcvtss2si32:
1542   case Intrinsic::x86_avx512_vcvtss2si64:
1543   case Intrinsic::x86_avx512_cvttss2si:
1544   case Intrinsic::x86_avx512_cvttss2si64:
1545   case Intrinsic::x86_avx512_vcvtsd2si32:
1546   case Intrinsic::x86_avx512_vcvtsd2si64:
1547   case Intrinsic::x86_avx512_cvttsd2si:
1548   case Intrinsic::x86_avx512_cvttsd2si64:
1549   case Intrinsic::x86_avx512_vcvtss2usi32:
1550   case Intrinsic::x86_avx512_vcvtss2usi64:
1551   case Intrinsic::x86_avx512_cvttss2usi:
1552   case Intrinsic::x86_avx512_cvttss2usi64:
1553   case Intrinsic::x86_avx512_vcvtsd2usi32:
1554   case Intrinsic::x86_avx512_vcvtsd2usi64:
1555   case Intrinsic::x86_avx512_cvttsd2usi:
1556   case Intrinsic::x86_avx512_cvttsd2usi64:
1557     return !Call->isStrictFP();
1558 
1559   // Sign operations are actually bitwise operations, they do not raise
1560   // exceptions even for SNANs.
1561   case Intrinsic::fabs:
1562   case Intrinsic::copysign:
1563   // Non-constrained variants of rounding operations means default FP
1564   // environment, they can be folded in any case.
1565   case Intrinsic::ceil:
1566   case Intrinsic::floor:
1567   case Intrinsic::round:
1568   case Intrinsic::roundeven:
1569   case Intrinsic::trunc:
1570   case Intrinsic::nearbyint:
1571   case Intrinsic::rint:
1572   // Constrained intrinsics can be folded if FP environment is known
1573   // to compiler.
1574   case Intrinsic::experimental_constrained_ceil:
1575   case Intrinsic::experimental_constrained_floor:
1576   case Intrinsic::experimental_constrained_round:
1577   case Intrinsic::experimental_constrained_roundeven:
1578   case Intrinsic::experimental_constrained_trunc:
1579   case Intrinsic::experimental_constrained_nearbyint:
1580   case Intrinsic::experimental_constrained_rint:
1581     return true;
1582   default:
1583     return false;
1584   case Intrinsic::not_intrinsic: break;
1585   }
1586 
1587   if (!F->hasName() || Call->isStrictFP())
1588     return false;
1589 
1590   // In these cases, the check of the length is required.  We don't want to
1591   // return true for a name like "cos\0blah" which strcmp would return equal to
1592   // "cos", but has length 8.
1593   StringRef Name = F->getName();
1594   switch (Name[0]) {
1595   default:
1596     return false;
1597   case 'a':
1598     return Name == "acos" || Name == "acosf" ||
1599            Name == "asin" || Name == "asinf" ||
1600            Name == "atan" || Name == "atanf" ||
1601            Name == "atan2" || Name == "atan2f";
1602   case 'c':
1603     return Name == "ceil" || Name == "ceilf" ||
1604            Name == "cos" || Name == "cosf" ||
1605            Name == "cosh" || Name == "coshf";
1606   case 'e':
1607     return Name == "exp" || Name == "expf" ||
1608            Name == "exp2" || Name == "exp2f";
1609   case 'f':
1610     return Name == "fabs" || Name == "fabsf" ||
1611            Name == "floor" || Name == "floorf" ||
1612            Name == "fmod" || Name == "fmodf";
1613   case 'l':
1614     return Name == "log" || Name == "logf" ||
1615            Name == "log2" || Name == "log2f" ||
1616            Name == "log10" || Name == "log10f";
1617   case 'n':
1618     return Name == "nearbyint" || Name == "nearbyintf";
1619   case 'p':
1620     return Name == "pow" || Name == "powf";
1621   case 'r':
1622     return Name == "remainder" || Name == "remainderf" ||
1623            Name == "rint" || Name == "rintf" ||
1624            Name == "round" || Name == "roundf";
1625   case 's':
1626     return Name == "sin" || Name == "sinf" ||
1627            Name == "sinh" || Name == "sinhf" ||
1628            Name == "sqrt" || Name == "sqrtf";
1629   case 't':
1630     return Name == "tan" || Name == "tanf" ||
1631            Name == "tanh" || Name == "tanhf" ||
1632            Name == "trunc" || Name == "truncf";
1633   case '_':
1634     // Check for various function names that get used for the math functions
1635     // when the header files are preprocessed with the macro
1636     // __FINITE_MATH_ONLY__ enabled.
1637     // The '12' here is the length of the shortest name that can match.
1638     // We need to check the size before looking at Name[1] and Name[2]
1639     // so we may as well check a limit that will eliminate mismatches.
1640     if (Name.size() < 12 || Name[1] != '_')
1641       return false;
1642     switch (Name[2]) {
1643     default:
1644       return false;
1645     case 'a':
1646       return Name == "__acos_finite" || Name == "__acosf_finite" ||
1647              Name == "__asin_finite" || Name == "__asinf_finite" ||
1648              Name == "__atan2_finite" || Name == "__atan2f_finite";
1649     case 'c':
1650       return Name == "__cosh_finite" || Name == "__coshf_finite";
1651     case 'e':
1652       return Name == "__exp_finite" || Name == "__expf_finite" ||
1653              Name == "__exp2_finite" || Name == "__exp2f_finite";
1654     case 'l':
1655       return Name == "__log_finite" || Name == "__logf_finite" ||
1656              Name == "__log10_finite" || Name == "__log10f_finite";
1657     case 'p':
1658       return Name == "__pow_finite" || Name == "__powf_finite";
1659     case 's':
1660       return Name == "__sinh_finite" || Name == "__sinhf_finite";
1661     }
1662   }
1663 }
1664 
1665 namespace {
1666 
1667 Constant *GetConstantFoldFPValue(double V, Type *Ty) {
1668   if (Ty->isHalfTy() || Ty->isFloatTy()) {
1669     APFloat APF(V);
1670     bool unused;
1671     APF.convert(Ty->getFltSemantics(), APFloat::rmNearestTiesToEven, &unused);
1672     return ConstantFP::get(Ty->getContext(), APF);
1673   }
1674   if (Ty->isDoubleTy())
1675     return ConstantFP::get(Ty->getContext(), APFloat(V));
1676   llvm_unreachable("Can only constant fold half/float/double");
1677 }
1678 
1679 /// Clear the floating-point exception state.
1680 inline void llvm_fenv_clearexcept() {
1681 #if defined(HAVE_FENV_H) && HAVE_DECL_FE_ALL_EXCEPT
1682   feclearexcept(FE_ALL_EXCEPT);
1683 #endif
1684   errno = 0;
1685 }
1686 
1687 /// Test if a floating-point exception was raised.
1688 inline bool llvm_fenv_testexcept() {
1689   int errno_val = errno;
1690   if (errno_val == ERANGE || errno_val == EDOM)
1691     return true;
1692 #if defined(HAVE_FENV_H) && HAVE_DECL_FE_ALL_EXCEPT && HAVE_DECL_FE_INEXACT
1693   if (fetestexcept(FE_ALL_EXCEPT & ~FE_INEXACT))
1694     return true;
1695 #endif
1696   return false;
1697 }
1698 
1699 Constant *ConstantFoldFP(double (*NativeFP)(double), double V, Type *Ty) {
1700   llvm_fenv_clearexcept();
1701   V = NativeFP(V);
1702   if (llvm_fenv_testexcept()) {
1703     llvm_fenv_clearexcept();
1704     return nullptr;
1705   }
1706 
1707   return GetConstantFoldFPValue(V, Ty);
1708 }
1709 
1710 Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double), double V,
1711                                double W, Type *Ty) {
1712   llvm_fenv_clearexcept();
1713   V = NativeFP(V, W);
1714   if (llvm_fenv_testexcept()) {
1715     llvm_fenv_clearexcept();
1716     return nullptr;
1717   }
1718 
1719   return GetConstantFoldFPValue(V, Ty);
1720 }
1721 
1722 Constant *ConstantFoldVectorReduce(Intrinsic::ID IID, Constant *Op) {
1723   FixedVectorType *VT = dyn_cast<FixedVectorType>(Op->getType());
1724   if (!VT)
1725     return nullptr;
1726   ConstantInt *CI = dyn_cast<ConstantInt>(Op->getAggregateElement(0U));
1727   if (!CI)
1728     return nullptr;
1729   APInt Acc = CI->getValue();
1730 
1731   for (unsigned I = 1; I < VT->getNumElements(); I++) {
1732     if (!(CI = dyn_cast<ConstantInt>(Op->getAggregateElement(I))))
1733       return nullptr;
1734     const APInt &X = CI->getValue();
1735     switch (IID) {
1736     case Intrinsic::vector_reduce_add:
1737       Acc = Acc + X;
1738       break;
1739     case Intrinsic::vector_reduce_mul:
1740       Acc = Acc * X;
1741       break;
1742     case Intrinsic::vector_reduce_and:
1743       Acc = Acc & X;
1744       break;
1745     case Intrinsic::vector_reduce_or:
1746       Acc = Acc | X;
1747       break;
1748     case Intrinsic::vector_reduce_xor:
1749       Acc = Acc ^ X;
1750       break;
1751     case Intrinsic::vector_reduce_smin:
1752       Acc = APIntOps::smin(Acc, X);
1753       break;
1754     case Intrinsic::vector_reduce_smax:
1755       Acc = APIntOps::smax(Acc, X);
1756       break;
1757     case Intrinsic::vector_reduce_umin:
1758       Acc = APIntOps::umin(Acc, X);
1759       break;
1760     case Intrinsic::vector_reduce_umax:
1761       Acc = APIntOps::umax(Acc, X);
1762       break;
1763     }
1764   }
1765 
1766   return ConstantInt::get(Op->getContext(), Acc);
1767 }
1768 
1769 /// Attempt to fold an SSE floating point to integer conversion of a constant
1770 /// floating point. If roundTowardZero is false, the default IEEE rounding is
1771 /// used (toward nearest, ties to even). This matches the behavior of the
1772 /// non-truncating SSE instructions in the default rounding mode. The desired
1773 /// integer type Ty is used to select how many bits are available for the
1774 /// result. Returns null if the conversion cannot be performed, otherwise
1775 /// returns the Constant value resulting from the conversion.
1776 Constant *ConstantFoldSSEConvertToInt(const APFloat &Val, bool roundTowardZero,
1777                                       Type *Ty, bool IsSigned) {
1778   // All of these conversion intrinsics form an integer of at most 64bits.
1779   unsigned ResultWidth = Ty->getIntegerBitWidth();
1780   assert(ResultWidth <= 64 &&
1781          "Can only constant fold conversions to 64 and 32 bit ints");
1782 
1783   uint64_t UIntVal;
1784   bool isExact = false;
1785   APFloat::roundingMode mode = roundTowardZero? APFloat::rmTowardZero
1786                                               : APFloat::rmNearestTiesToEven;
1787   APFloat::opStatus status =
1788       Val.convertToInteger(makeMutableArrayRef(UIntVal), ResultWidth,
1789                            IsSigned, mode, &isExact);
1790   if (status != APFloat::opOK &&
1791       (!roundTowardZero || status != APFloat::opInexact))
1792     return nullptr;
1793   return ConstantInt::get(Ty, UIntVal, IsSigned);
1794 }
1795 
1796 double getValueAsDouble(ConstantFP *Op) {
1797   Type *Ty = Op->getType();
1798 
1799   if (Ty->isFloatTy())
1800     return Op->getValueAPF().convertToFloat();
1801 
1802   if (Ty->isDoubleTy())
1803     return Op->getValueAPF().convertToDouble();
1804 
1805   bool unused;
1806   APFloat APF = Op->getValueAPF();
1807   APF.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven, &unused);
1808   return APF.convertToDouble();
1809 }
1810 
1811 static bool getConstIntOrUndef(Value *Op, const APInt *&C) {
1812   if (auto *CI = dyn_cast<ConstantInt>(Op)) {
1813     C = &CI->getValue();
1814     return true;
1815   }
1816   if (isa<UndefValue>(Op)) {
1817     C = nullptr;
1818     return true;
1819   }
1820   return false;
1821 }
1822 
1823 static Constant *ConstantFoldScalarCall1(StringRef Name,
1824                                          Intrinsic::ID IntrinsicID,
1825                                          Type *Ty,
1826                                          ArrayRef<Constant *> Operands,
1827                                          const TargetLibraryInfo *TLI,
1828                                          const CallBase *Call) {
1829   assert(Operands.size() == 1 && "Wrong number of operands.");
1830 
1831   if (IntrinsicID == Intrinsic::is_constant) {
1832     // We know we have a "Constant" argument. But we want to only
1833     // return true for manifest constants, not those that depend on
1834     // constants with unknowable values, e.g. GlobalValue or BlockAddress.
1835     if (Operands[0]->isManifestConstant())
1836       return ConstantInt::getTrue(Ty->getContext());
1837     return nullptr;
1838   }
1839   if (isa<UndefValue>(Operands[0])) {
1840     // cosine(arg) is between -1 and 1. cosine(invalid arg) is NaN.
1841     // ctpop() is between 0 and bitwidth, pick 0 for undef.
1842     // fptoui.sat and fptosi.sat can always fold to zero (for a zero input).
1843     if (IntrinsicID == Intrinsic::cos ||
1844         IntrinsicID == Intrinsic::ctpop ||
1845         IntrinsicID == Intrinsic::fptoui_sat ||
1846         IntrinsicID == Intrinsic::fptosi_sat)
1847       return Constant::getNullValue(Ty);
1848     if (IntrinsicID == Intrinsic::bswap ||
1849         IntrinsicID == Intrinsic::bitreverse ||
1850         IntrinsicID == Intrinsic::launder_invariant_group ||
1851         IntrinsicID == Intrinsic::strip_invariant_group)
1852       return Operands[0];
1853   }
1854 
1855   if (isa<ConstantPointerNull>(Operands[0])) {
1856     // launder(null) == null == strip(null) iff in addrspace 0
1857     if (IntrinsicID == Intrinsic::launder_invariant_group ||
1858         IntrinsicID == Intrinsic::strip_invariant_group) {
1859       // If instruction is not yet put in a basic block (e.g. when cloning
1860       // a function during inlining), Call's caller may not be available.
1861       // So check Call's BB first before querying Call->getCaller.
1862       const Function *Caller =
1863           Call->getParent() ? Call->getCaller() : nullptr;
1864       if (Caller &&
1865           !NullPointerIsDefined(
1866               Caller, Operands[0]->getType()->getPointerAddressSpace())) {
1867         return Operands[0];
1868       }
1869       return nullptr;
1870     }
1871   }
1872 
1873   if (auto *Op = dyn_cast<ConstantFP>(Operands[0])) {
1874     if (IntrinsicID == Intrinsic::convert_to_fp16) {
1875       APFloat Val(Op->getValueAPF());
1876 
1877       bool lost = false;
1878       Val.convert(APFloat::IEEEhalf(), APFloat::rmNearestTiesToEven, &lost);
1879 
1880       return ConstantInt::get(Ty->getContext(), Val.bitcastToAPInt());
1881     }
1882 
1883     APFloat U = Op->getValueAPF();
1884 
1885     if (IntrinsicID == Intrinsic::wasm_trunc_signed ||
1886         IntrinsicID == Intrinsic::wasm_trunc_unsigned ||
1887         IntrinsicID == Intrinsic::wasm_trunc_saturate_signed ||
1888         IntrinsicID == Intrinsic::wasm_trunc_saturate_unsigned) {
1889 
1890       bool Saturating = IntrinsicID == Intrinsic::wasm_trunc_saturate_signed ||
1891                         IntrinsicID == Intrinsic::wasm_trunc_saturate_unsigned;
1892       bool Signed = IntrinsicID == Intrinsic::wasm_trunc_signed ||
1893                     IntrinsicID == Intrinsic::wasm_trunc_saturate_signed;
1894 
1895       if (U.isNaN())
1896         return Saturating ? ConstantInt::get(Ty, 0) : nullptr;
1897 
1898       unsigned Width = Ty->getIntegerBitWidth();
1899       APSInt Int(Width, !Signed);
1900       bool IsExact = false;
1901       APFloat::opStatus Status =
1902           U.convertToInteger(Int, APFloat::rmTowardZero, &IsExact);
1903 
1904       if (Status == APFloat::opOK || Status == APFloat::opInexact)
1905         return ConstantInt::get(Ty, Int);
1906 
1907       if (!Saturating)
1908         return nullptr;
1909 
1910       if (U.isNegative())
1911         return Signed ? ConstantInt::get(Ty, APInt::getSignedMinValue(Width))
1912                       : ConstantInt::get(Ty, APInt::getMinValue(Width));
1913       else
1914         return Signed ? ConstantInt::get(Ty, APInt::getSignedMaxValue(Width))
1915                       : ConstantInt::get(Ty, APInt::getMaxValue(Width));
1916     }
1917 
1918     if (IntrinsicID == Intrinsic::fptoui_sat ||
1919         IntrinsicID == Intrinsic::fptosi_sat) {
1920       // convertToInteger() already has the desired saturation semantics.
1921       APSInt Int(Ty->getIntegerBitWidth(),
1922                  IntrinsicID == Intrinsic::fptoui_sat);
1923       bool IsExact;
1924       U.convertToInteger(Int, APFloat::rmTowardZero, &IsExact);
1925       return ConstantInt::get(Ty, Int);
1926     }
1927 
1928     if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
1929       return nullptr;
1930 
1931     // Use internal versions of these intrinsics.
1932 
1933     if (IntrinsicID == Intrinsic::nearbyint || IntrinsicID == Intrinsic::rint) {
1934       U.roundToIntegral(APFloat::rmNearestTiesToEven);
1935       return ConstantFP::get(Ty->getContext(), U);
1936     }
1937 
1938     if (IntrinsicID == Intrinsic::round) {
1939       U.roundToIntegral(APFloat::rmNearestTiesToAway);
1940       return ConstantFP::get(Ty->getContext(), U);
1941     }
1942 
1943     if (IntrinsicID == Intrinsic::roundeven) {
1944       U.roundToIntegral(APFloat::rmNearestTiesToEven);
1945       return ConstantFP::get(Ty->getContext(), U);
1946     }
1947 
1948     if (IntrinsicID == Intrinsic::ceil) {
1949       U.roundToIntegral(APFloat::rmTowardPositive);
1950       return ConstantFP::get(Ty->getContext(), U);
1951     }
1952 
1953     if (IntrinsicID == Intrinsic::floor) {
1954       U.roundToIntegral(APFloat::rmTowardNegative);
1955       return ConstantFP::get(Ty->getContext(), U);
1956     }
1957 
1958     if (IntrinsicID == Intrinsic::trunc) {
1959       U.roundToIntegral(APFloat::rmTowardZero);
1960       return ConstantFP::get(Ty->getContext(), U);
1961     }
1962 
1963     if (IntrinsicID == Intrinsic::fabs) {
1964       U.clearSign();
1965       return ConstantFP::get(Ty->getContext(), U);
1966     }
1967 
1968     if (IntrinsicID == Intrinsic::amdgcn_fract) {
1969       // The v_fract instruction behaves like the OpenCL spec, which defines
1970       // fract(x) as fmin(x - floor(x), 0x1.fffffep-1f): "The min() operator is
1971       //   there to prevent fract(-small) from returning 1.0. It returns the
1972       //   largest positive floating-point number less than 1.0."
1973       APFloat FloorU(U);
1974       FloorU.roundToIntegral(APFloat::rmTowardNegative);
1975       APFloat FractU(U - FloorU);
1976       APFloat AlmostOne(U.getSemantics(), 1);
1977       AlmostOne.next(/*nextDown*/ true);
1978       return ConstantFP::get(Ty->getContext(), minimum(FractU, AlmostOne));
1979     }
1980 
1981     // Rounding operations (floor, trunc, ceil, round and nearbyint) do not
1982     // raise FP exceptions, unless the argument is signaling NaN.
1983 
1984     Optional<APFloat::roundingMode> RM;
1985     switch (IntrinsicID) {
1986     default:
1987       break;
1988     case Intrinsic::experimental_constrained_nearbyint:
1989     case Intrinsic::experimental_constrained_rint: {
1990       auto CI = cast<ConstrainedFPIntrinsic>(Call);
1991       RM = CI->getRoundingMode();
1992       if (!RM || RM.getValue() == RoundingMode::Dynamic)
1993         return nullptr;
1994       break;
1995     }
1996     case Intrinsic::experimental_constrained_round:
1997       RM = APFloat::rmNearestTiesToAway;
1998       break;
1999     case Intrinsic::experimental_constrained_ceil:
2000       RM = APFloat::rmTowardPositive;
2001       break;
2002     case Intrinsic::experimental_constrained_floor:
2003       RM = APFloat::rmTowardNegative;
2004       break;
2005     case Intrinsic::experimental_constrained_trunc:
2006       RM = APFloat::rmTowardZero;
2007       break;
2008     }
2009     if (RM) {
2010       auto CI = cast<ConstrainedFPIntrinsic>(Call);
2011       if (U.isFinite()) {
2012         APFloat::opStatus St = U.roundToIntegral(*RM);
2013         if (IntrinsicID == Intrinsic::experimental_constrained_rint &&
2014             St == APFloat::opInexact) {
2015           Optional<fp::ExceptionBehavior> EB = CI->getExceptionBehavior();
2016           if (EB && *EB == fp::ebStrict)
2017             return nullptr;
2018         }
2019       } else if (U.isSignaling()) {
2020         Optional<fp::ExceptionBehavior> EB = CI->getExceptionBehavior();
2021         if (EB && *EB != fp::ebIgnore)
2022           return nullptr;
2023         U = APFloat::getQNaN(U.getSemantics());
2024       }
2025       return ConstantFP::get(Ty->getContext(), U);
2026     }
2027 
2028     /// We only fold functions with finite arguments. Folding NaN and inf is
2029     /// likely to be aborted with an exception anyway, and some host libms
2030     /// have known errors raising exceptions.
2031     if (!U.isFinite())
2032       return nullptr;
2033 
2034     /// Currently APFloat versions of these functions do not exist, so we use
2035     /// the host native double versions.  Float versions are not called
2036     /// directly but for all these it is true (float)(f((double)arg)) ==
2037     /// f(arg).  Long double not supported yet.
2038     double V = getValueAsDouble(Op);
2039 
2040     switch (IntrinsicID) {
2041       default: break;
2042       case Intrinsic::log:
2043         return ConstantFoldFP(log, V, Ty);
2044       case Intrinsic::log2:
2045         // TODO: What about hosts that lack a C99 library?
2046         return ConstantFoldFP(Log2, V, Ty);
2047       case Intrinsic::log10:
2048         // TODO: What about hosts that lack a C99 library?
2049         return ConstantFoldFP(log10, V, Ty);
2050       case Intrinsic::exp:
2051         return ConstantFoldFP(exp, V, Ty);
2052       case Intrinsic::exp2:
2053         // Fold exp2(x) as pow(2, x), in case the host lacks a C99 library.
2054         return ConstantFoldBinaryFP(pow, 2.0, V, Ty);
2055       case Intrinsic::sin:
2056         return ConstantFoldFP(sin, V, Ty);
2057       case Intrinsic::cos:
2058         return ConstantFoldFP(cos, V, Ty);
2059       case Intrinsic::sqrt:
2060         return ConstantFoldFP(sqrt, V, Ty);
2061       case Intrinsic::amdgcn_cos:
2062       case Intrinsic::amdgcn_sin:
2063         if (V < -256.0 || V > 256.0)
2064           // The gfx8 and gfx9 architectures handle arguments outside the range
2065           // [-256, 256] differently. This should be a rare case so bail out
2066           // rather than trying to handle the difference.
2067           return nullptr;
2068         bool IsCos = IntrinsicID == Intrinsic::amdgcn_cos;
2069         double V4 = V * 4.0;
2070         if (V4 == floor(V4)) {
2071           // Force exact results for quarter-integer inputs.
2072           const double SinVals[4] = { 0.0, 1.0, 0.0, -1.0 };
2073           V = SinVals[((int)V4 + (IsCos ? 1 : 0)) & 3];
2074         } else {
2075           if (IsCos)
2076             V = cos(V * 2.0 * numbers::pi);
2077           else
2078             V = sin(V * 2.0 * numbers::pi);
2079         }
2080         return GetConstantFoldFPValue(V, Ty);
2081     }
2082 
2083     if (!TLI)
2084       return nullptr;
2085 
2086     LibFunc Func = NotLibFunc;
2087     TLI->getLibFunc(Name, Func);
2088     switch (Func) {
2089     default:
2090       break;
2091     case LibFunc_acos:
2092     case LibFunc_acosf:
2093     case LibFunc_acos_finite:
2094     case LibFunc_acosf_finite:
2095       if (TLI->has(Func))
2096         return ConstantFoldFP(acos, V, Ty);
2097       break;
2098     case LibFunc_asin:
2099     case LibFunc_asinf:
2100     case LibFunc_asin_finite:
2101     case LibFunc_asinf_finite:
2102       if (TLI->has(Func))
2103         return ConstantFoldFP(asin, V, Ty);
2104       break;
2105     case LibFunc_atan:
2106     case LibFunc_atanf:
2107       if (TLI->has(Func))
2108         return ConstantFoldFP(atan, V, Ty);
2109       break;
2110     case LibFunc_ceil:
2111     case LibFunc_ceilf:
2112       if (TLI->has(Func)) {
2113         U.roundToIntegral(APFloat::rmTowardPositive);
2114         return ConstantFP::get(Ty->getContext(), U);
2115       }
2116       break;
2117     case LibFunc_cos:
2118     case LibFunc_cosf:
2119       if (TLI->has(Func))
2120         return ConstantFoldFP(cos, V, Ty);
2121       break;
2122     case LibFunc_cosh:
2123     case LibFunc_coshf:
2124     case LibFunc_cosh_finite:
2125     case LibFunc_coshf_finite:
2126       if (TLI->has(Func))
2127         return ConstantFoldFP(cosh, V, Ty);
2128       break;
2129     case LibFunc_exp:
2130     case LibFunc_expf:
2131     case LibFunc_exp_finite:
2132     case LibFunc_expf_finite:
2133       if (TLI->has(Func))
2134         return ConstantFoldFP(exp, V, Ty);
2135       break;
2136     case LibFunc_exp2:
2137     case LibFunc_exp2f:
2138     case LibFunc_exp2_finite:
2139     case LibFunc_exp2f_finite:
2140       if (TLI->has(Func))
2141         // Fold exp2(x) as pow(2, x), in case the host lacks a C99 library.
2142         return ConstantFoldBinaryFP(pow, 2.0, V, Ty);
2143       break;
2144     case LibFunc_fabs:
2145     case LibFunc_fabsf:
2146       if (TLI->has(Func)) {
2147         U.clearSign();
2148         return ConstantFP::get(Ty->getContext(), U);
2149       }
2150       break;
2151     case LibFunc_floor:
2152     case LibFunc_floorf:
2153       if (TLI->has(Func)) {
2154         U.roundToIntegral(APFloat::rmTowardNegative);
2155         return ConstantFP::get(Ty->getContext(), U);
2156       }
2157       break;
2158     case LibFunc_log:
2159     case LibFunc_logf:
2160     case LibFunc_log_finite:
2161     case LibFunc_logf_finite:
2162       if (V > 0.0 && TLI->has(Func))
2163         return ConstantFoldFP(log, V, Ty);
2164       break;
2165     case LibFunc_log2:
2166     case LibFunc_log2f:
2167     case LibFunc_log2_finite:
2168     case LibFunc_log2f_finite:
2169       if (V > 0.0 && TLI->has(Func))
2170         // TODO: What about hosts that lack a C99 library?
2171         return ConstantFoldFP(Log2, V, Ty);
2172       break;
2173     case LibFunc_log10:
2174     case LibFunc_log10f:
2175     case LibFunc_log10_finite:
2176     case LibFunc_log10f_finite:
2177       if (V > 0.0 && TLI->has(Func))
2178         // TODO: What about hosts that lack a C99 library?
2179         return ConstantFoldFP(log10, V, Ty);
2180       break;
2181     case LibFunc_nearbyint:
2182     case LibFunc_nearbyintf:
2183     case LibFunc_rint:
2184     case LibFunc_rintf:
2185       if (TLI->has(Func)) {
2186         U.roundToIntegral(APFloat::rmNearestTiesToEven);
2187         return ConstantFP::get(Ty->getContext(), U);
2188       }
2189       break;
2190     case LibFunc_round:
2191     case LibFunc_roundf:
2192       if (TLI->has(Func)) {
2193         U.roundToIntegral(APFloat::rmNearestTiesToAway);
2194         return ConstantFP::get(Ty->getContext(), U);
2195       }
2196       break;
2197     case LibFunc_sin:
2198     case LibFunc_sinf:
2199       if (TLI->has(Func))
2200         return ConstantFoldFP(sin, V, Ty);
2201       break;
2202     case LibFunc_sinh:
2203     case LibFunc_sinhf:
2204     case LibFunc_sinh_finite:
2205     case LibFunc_sinhf_finite:
2206       if (TLI->has(Func))
2207         return ConstantFoldFP(sinh, V, Ty);
2208       break;
2209     case LibFunc_sqrt:
2210     case LibFunc_sqrtf:
2211       if (V >= 0.0 && TLI->has(Func))
2212         return ConstantFoldFP(sqrt, V, Ty);
2213       break;
2214     case LibFunc_tan:
2215     case LibFunc_tanf:
2216       if (TLI->has(Func))
2217         return ConstantFoldFP(tan, V, Ty);
2218       break;
2219     case LibFunc_tanh:
2220     case LibFunc_tanhf:
2221       if (TLI->has(Func))
2222         return ConstantFoldFP(tanh, V, Ty);
2223       break;
2224     case LibFunc_trunc:
2225     case LibFunc_truncf:
2226       if (TLI->has(Func)) {
2227         U.roundToIntegral(APFloat::rmTowardZero);
2228         return ConstantFP::get(Ty->getContext(), U);
2229       }
2230       break;
2231     }
2232     return nullptr;
2233   }
2234 
2235   if (auto *Op = dyn_cast<ConstantInt>(Operands[0])) {
2236     switch (IntrinsicID) {
2237     case Intrinsic::bswap:
2238       return ConstantInt::get(Ty->getContext(), Op->getValue().byteSwap());
2239     case Intrinsic::ctpop:
2240       return ConstantInt::get(Ty, Op->getValue().countPopulation());
2241     case Intrinsic::bitreverse:
2242       return ConstantInt::get(Ty->getContext(), Op->getValue().reverseBits());
2243     case Intrinsic::convert_from_fp16: {
2244       APFloat Val(APFloat::IEEEhalf(), Op->getValue());
2245 
2246       bool lost = false;
2247       APFloat::opStatus status = Val.convert(
2248           Ty->getFltSemantics(), APFloat::rmNearestTiesToEven, &lost);
2249 
2250       // Conversion is always precise.
2251       (void)status;
2252       assert(status == APFloat::opOK && !lost &&
2253              "Precision lost during fp16 constfolding");
2254 
2255       return ConstantFP::get(Ty->getContext(), Val);
2256     }
2257     default:
2258       return nullptr;
2259     }
2260   }
2261 
2262   if (isa<ConstantAggregateZero>(Operands[0])) {
2263     switch (IntrinsicID) {
2264     default: break;
2265     case Intrinsic::vector_reduce_add:
2266     case Intrinsic::vector_reduce_mul:
2267     case Intrinsic::vector_reduce_and:
2268     case Intrinsic::vector_reduce_or:
2269     case Intrinsic::vector_reduce_xor:
2270     case Intrinsic::vector_reduce_smin:
2271     case Intrinsic::vector_reduce_smax:
2272     case Intrinsic::vector_reduce_umin:
2273     case Intrinsic::vector_reduce_umax:
2274       return ConstantInt::get(Ty, 0);
2275     }
2276   }
2277 
2278   // Support ConstantVector in case we have an Undef in the top.
2279   if (isa<ConstantVector>(Operands[0]) ||
2280       isa<ConstantDataVector>(Operands[0])) {
2281     auto *Op = cast<Constant>(Operands[0]);
2282     switch (IntrinsicID) {
2283     default: break;
2284     case Intrinsic::vector_reduce_add:
2285     case Intrinsic::vector_reduce_mul:
2286     case Intrinsic::vector_reduce_and:
2287     case Intrinsic::vector_reduce_or:
2288     case Intrinsic::vector_reduce_xor:
2289     case Intrinsic::vector_reduce_smin:
2290     case Intrinsic::vector_reduce_smax:
2291     case Intrinsic::vector_reduce_umin:
2292     case Intrinsic::vector_reduce_umax:
2293       if (Constant *C = ConstantFoldVectorReduce(IntrinsicID, Op))
2294         return C;
2295       break;
2296     case Intrinsic::x86_sse_cvtss2si:
2297     case Intrinsic::x86_sse_cvtss2si64:
2298     case Intrinsic::x86_sse2_cvtsd2si:
2299     case Intrinsic::x86_sse2_cvtsd2si64:
2300       if (ConstantFP *FPOp =
2301               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2302         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2303                                            /*roundTowardZero=*/false, Ty,
2304                                            /*IsSigned*/true);
2305       break;
2306     case Intrinsic::x86_sse_cvttss2si:
2307     case Intrinsic::x86_sse_cvttss2si64:
2308     case Intrinsic::x86_sse2_cvttsd2si:
2309     case Intrinsic::x86_sse2_cvttsd2si64:
2310       if (ConstantFP *FPOp =
2311               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2312         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2313                                            /*roundTowardZero=*/true, Ty,
2314                                            /*IsSigned*/true);
2315       break;
2316     }
2317   }
2318 
2319   return nullptr;
2320 }
2321 
2322 static Constant *ConstantFoldScalarCall2(StringRef Name,
2323                                          Intrinsic::ID IntrinsicID,
2324                                          Type *Ty,
2325                                          ArrayRef<Constant *> Operands,
2326                                          const TargetLibraryInfo *TLI,
2327                                          const CallBase *Call) {
2328   assert(Operands.size() == 2 && "Wrong number of operands.");
2329 
2330   if (Ty->isFloatingPointTy()) {
2331     // TODO: We should have undef handling for all of the FP intrinsics that
2332     //       are attempted to be folded in this function.
2333     bool IsOp0Undef = isa<UndefValue>(Operands[0]);
2334     bool IsOp1Undef = isa<UndefValue>(Operands[1]);
2335     switch (IntrinsicID) {
2336     case Intrinsic::maxnum:
2337     case Intrinsic::minnum:
2338     case Intrinsic::maximum:
2339     case Intrinsic::minimum:
2340       // If one argument is undef, return the other argument.
2341       if (IsOp0Undef)
2342         return Operands[1];
2343       if (IsOp1Undef)
2344         return Operands[0];
2345       break;
2346     }
2347   }
2348 
2349   if (auto *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
2350     if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
2351       return nullptr;
2352     double Op1V = getValueAsDouble(Op1);
2353 
2354     if (auto *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
2355       if (Op2->getType() != Op1->getType())
2356         return nullptr;
2357 
2358       double Op2V = getValueAsDouble(Op2);
2359       if (IntrinsicID == Intrinsic::pow) {
2360         return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
2361       }
2362       if (IntrinsicID == Intrinsic::copysign) {
2363         APFloat V1 = Op1->getValueAPF();
2364         const APFloat &V2 = Op2->getValueAPF();
2365         V1.copySign(V2);
2366         return ConstantFP::get(Ty->getContext(), V1);
2367       }
2368 
2369       if (IntrinsicID == Intrinsic::minnum) {
2370         const APFloat &C1 = Op1->getValueAPF();
2371         const APFloat &C2 = Op2->getValueAPF();
2372         return ConstantFP::get(Ty->getContext(), minnum(C1, C2));
2373       }
2374 
2375       if (IntrinsicID == Intrinsic::maxnum) {
2376         const APFloat &C1 = Op1->getValueAPF();
2377         const APFloat &C2 = Op2->getValueAPF();
2378         return ConstantFP::get(Ty->getContext(), maxnum(C1, C2));
2379       }
2380 
2381       if (IntrinsicID == Intrinsic::minimum) {
2382         const APFloat &C1 = Op1->getValueAPF();
2383         const APFloat &C2 = Op2->getValueAPF();
2384         return ConstantFP::get(Ty->getContext(), minimum(C1, C2));
2385       }
2386 
2387       if (IntrinsicID == Intrinsic::maximum) {
2388         const APFloat &C1 = Op1->getValueAPF();
2389         const APFloat &C2 = Op2->getValueAPF();
2390         return ConstantFP::get(Ty->getContext(), maximum(C1, C2));
2391       }
2392 
2393       if (IntrinsicID == Intrinsic::amdgcn_fmul_legacy) {
2394         const APFloat &C1 = Op1->getValueAPF();
2395         const APFloat &C2 = Op2->getValueAPF();
2396         // The legacy behaviour is that multiplying +/- 0.0 by anything, even
2397         // NaN or infinity, gives +0.0.
2398         if (C1.isZero() || C2.isZero())
2399           return ConstantFP::getNullValue(Ty);
2400         return ConstantFP::get(Ty->getContext(), C1 * C2);
2401       }
2402 
2403       if (!TLI)
2404         return nullptr;
2405 
2406       LibFunc Func = NotLibFunc;
2407       TLI->getLibFunc(Name, Func);
2408       switch (Func) {
2409       default:
2410         break;
2411       case LibFunc_pow:
2412       case LibFunc_powf:
2413       case LibFunc_pow_finite:
2414       case LibFunc_powf_finite:
2415         if (TLI->has(Func))
2416           return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
2417         break;
2418       case LibFunc_fmod:
2419       case LibFunc_fmodf:
2420         if (TLI->has(Func)) {
2421           APFloat V = Op1->getValueAPF();
2422           if (APFloat::opStatus::opOK == V.mod(Op2->getValueAPF()))
2423             return ConstantFP::get(Ty->getContext(), V);
2424         }
2425         break;
2426       case LibFunc_remainder:
2427       case LibFunc_remainderf:
2428         if (TLI->has(Func)) {
2429           APFloat V = Op1->getValueAPF();
2430           if (APFloat::opStatus::opOK == V.remainder(Op2->getValueAPF()))
2431             return ConstantFP::get(Ty->getContext(), V);
2432         }
2433         break;
2434       case LibFunc_atan2:
2435       case LibFunc_atan2f:
2436       case LibFunc_atan2_finite:
2437       case LibFunc_atan2f_finite:
2438         if (TLI->has(Func))
2439           return ConstantFoldBinaryFP(atan2, Op1V, Op2V, Ty);
2440         break;
2441       }
2442     } else if (auto *Op2C = dyn_cast<ConstantInt>(Operands[1])) {
2443       if (IntrinsicID == Intrinsic::powi && Ty->isHalfTy())
2444         return ConstantFP::get(Ty->getContext(),
2445                                APFloat((float)std::pow((float)Op1V,
2446                                                (int)Op2C->getZExtValue())));
2447       if (IntrinsicID == Intrinsic::powi && Ty->isFloatTy())
2448         return ConstantFP::get(Ty->getContext(),
2449                                APFloat((float)std::pow((float)Op1V,
2450                                                (int)Op2C->getZExtValue())));
2451       if (IntrinsicID == Intrinsic::powi && Ty->isDoubleTy())
2452         return ConstantFP::get(Ty->getContext(),
2453                                APFloat((double)std::pow((double)Op1V,
2454                                                  (int)Op2C->getZExtValue())));
2455 
2456       if (IntrinsicID == Intrinsic::amdgcn_ldexp) {
2457         // FIXME: Should flush denorms depending on FP mode, but that's ignored
2458         // everywhere else.
2459 
2460         // scalbn is equivalent to ldexp with float radix 2
2461         APFloat Result = scalbn(Op1->getValueAPF(), Op2C->getSExtValue(),
2462                                 APFloat::rmNearestTiesToEven);
2463         return ConstantFP::get(Ty->getContext(), Result);
2464       }
2465     }
2466     return nullptr;
2467   }
2468 
2469   if (Operands[0]->getType()->isIntegerTy() &&
2470       Operands[1]->getType()->isIntegerTy()) {
2471     const APInt *C0, *C1;
2472     if (!getConstIntOrUndef(Operands[0], C0) ||
2473         !getConstIntOrUndef(Operands[1], C1))
2474       return nullptr;
2475 
2476     unsigned BitWidth = Ty->getScalarSizeInBits();
2477     switch (IntrinsicID) {
2478     default: break;
2479     case Intrinsic::smax:
2480       if (!C0 && !C1)
2481         return UndefValue::get(Ty);
2482       if (!C0 || !C1)
2483         return ConstantInt::get(Ty, APInt::getSignedMaxValue(BitWidth));
2484       return ConstantInt::get(Ty, C0->sgt(*C1) ? *C0 : *C1);
2485 
2486     case Intrinsic::smin:
2487       if (!C0 && !C1)
2488         return UndefValue::get(Ty);
2489       if (!C0 || !C1)
2490         return ConstantInt::get(Ty, APInt::getSignedMinValue(BitWidth));
2491       return ConstantInt::get(Ty, C0->slt(*C1) ? *C0 : *C1);
2492 
2493     case Intrinsic::umax:
2494       if (!C0 && !C1)
2495         return UndefValue::get(Ty);
2496       if (!C0 || !C1)
2497         return ConstantInt::get(Ty, APInt::getMaxValue(BitWidth));
2498       return ConstantInt::get(Ty, C0->ugt(*C1) ? *C0 : *C1);
2499 
2500     case Intrinsic::umin:
2501       if (!C0 && !C1)
2502         return UndefValue::get(Ty);
2503       if (!C0 || !C1)
2504         return ConstantInt::get(Ty, APInt::getMinValue(BitWidth));
2505       return ConstantInt::get(Ty, C0->ult(*C1) ? *C0 : *C1);
2506 
2507     case Intrinsic::usub_with_overflow:
2508     case Intrinsic::ssub_with_overflow:
2509     case Intrinsic::uadd_with_overflow:
2510     case Intrinsic::sadd_with_overflow:
2511       // X - undef -> { undef, false }
2512       // undef - X -> { undef, false }
2513       // X + undef -> { undef, false }
2514       // undef + x -> { undef, false }
2515       if (!C0 || !C1) {
2516         return ConstantStruct::get(
2517             cast<StructType>(Ty),
2518             {UndefValue::get(Ty->getStructElementType(0)),
2519              Constant::getNullValue(Ty->getStructElementType(1))});
2520       }
2521       LLVM_FALLTHROUGH;
2522     case Intrinsic::smul_with_overflow:
2523     case Intrinsic::umul_with_overflow: {
2524       // undef * X -> { 0, false }
2525       // X * undef -> { 0, false }
2526       if (!C0 || !C1)
2527         return Constant::getNullValue(Ty);
2528 
2529       APInt Res;
2530       bool Overflow;
2531       switch (IntrinsicID) {
2532       default: llvm_unreachable("Invalid case");
2533       case Intrinsic::sadd_with_overflow:
2534         Res = C0->sadd_ov(*C1, Overflow);
2535         break;
2536       case Intrinsic::uadd_with_overflow:
2537         Res = C0->uadd_ov(*C1, Overflow);
2538         break;
2539       case Intrinsic::ssub_with_overflow:
2540         Res = C0->ssub_ov(*C1, Overflow);
2541         break;
2542       case Intrinsic::usub_with_overflow:
2543         Res = C0->usub_ov(*C1, Overflow);
2544         break;
2545       case Intrinsic::smul_with_overflow:
2546         Res = C0->smul_ov(*C1, Overflow);
2547         break;
2548       case Intrinsic::umul_with_overflow:
2549         Res = C0->umul_ov(*C1, Overflow);
2550         break;
2551       }
2552       Constant *Ops[] = {
2553         ConstantInt::get(Ty->getContext(), Res),
2554         ConstantInt::get(Type::getInt1Ty(Ty->getContext()), Overflow)
2555       };
2556       return ConstantStruct::get(cast<StructType>(Ty), Ops);
2557     }
2558     case Intrinsic::uadd_sat:
2559     case Intrinsic::sadd_sat:
2560       if (!C0 && !C1)
2561         return UndefValue::get(Ty);
2562       if (!C0 || !C1)
2563         return Constant::getAllOnesValue(Ty);
2564       if (IntrinsicID == Intrinsic::uadd_sat)
2565         return ConstantInt::get(Ty, C0->uadd_sat(*C1));
2566       else
2567         return ConstantInt::get(Ty, C0->sadd_sat(*C1));
2568     case Intrinsic::usub_sat:
2569     case Intrinsic::ssub_sat:
2570       if (!C0 && !C1)
2571         return UndefValue::get(Ty);
2572       if (!C0 || !C1)
2573         return Constant::getNullValue(Ty);
2574       if (IntrinsicID == Intrinsic::usub_sat)
2575         return ConstantInt::get(Ty, C0->usub_sat(*C1));
2576       else
2577         return ConstantInt::get(Ty, C0->ssub_sat(*C1));
2578     case Intrinsic::cttz:
2579     case Intrinsic::ctlz:
2580       assert(C1 && "Must be constant int");
2581 
2582       // cttz(0, 1) and ctlz(0, 1) are undef.
2583       if (C1->isOneValue() && (!C0 || C0->isNullValue()))
2584         return UndefValue::get(Ty);
2585       if (!C0)
2586         return Constant::getNullValue(Ty);
2587       if (IntrinsicID == Intrinsic::cttz)
2588         return ConstantInt::get(Ty, C0->countTrailingZeros());
2589       else
2590         return ConstantInt::get(Ty, C0->countLeadingZeros());
2591 
2592     case Intrinsic::abs:
2593       // Undef or minimum val operand with poison min --> undef
2594       assert(C1 && "Must be constant int");
2595       if (C1->isOneValue() && (!C0 || C0->isMinSignedValue()))
2596         return UndefValue::get(Ty);
2597 
2598       // Undef operand with no poison min --> 0 (sign bit must be clear)
2599       if (C1->isNullValue() && !C0)
2600         return Constant::getNullValue(Ty);
2601 
2602       return ConstantInt::get(Ty, C0->abs());
2603     }
2604 
2605     return nullptr;
2606   }
2607 
2608   // Support ConstantVector in case we have an Undef in the top.
2609   if ((isa<ConstantVector>(Operands[0]) ||
2610        isa<ConstantDataVector>(Operands[0])) &&
2611       // Check for default rounding mode.
2612       // FIXME: Support other rounding modes?
2613       isa<ConstantInt>(Operands[1]) &&
2614       cast<ConstantInt>(Operands[1])->getValue() == 4) {
2615     auto *Op = cast<Constant>(Operands[0]);
2616     switch (IntrinsicID) {
2617     default: break;
2618     case Intrinsic::x86_avx512_vcvtss2si32:
2619     case Intrinsic::x86_avx512_vcvtss2si64:
2620     case Intrinsic::x86_avx512_vcvtsd2si32:
2621     case Intrinsic::x86_avx512_vcvtsd2si64:
2622       if (ConstantFP *FPOp =
2623               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2624         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2625                                            /*roundTowardZero=*/false, Ty,
2626                                            /*IsSigned*/true);
2627       break;
2628     case Intrinsic::x86_avx512_vcvtss2usi32:
2629     case Intrinsic::x86_avx512_vcvtss2usi64:
2630     case Intrinsic::x86_avx512_vcvtsd2usi32:
2631     case Intrinsic::x86_avx512_vcvtsd2usi64:
2632       if (ConstantFP *FPOp =
2633               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2634         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2635                                            /*roundTowardZero=*/false, Ty,
2636                                            /*IsSigned*/false);
2637       break;
2638     case Intrinsic::x86_avx512_cvttss2si:
2639     case Intrinsic::x86_avx512_cvttss2si64:
2640     case Intrinsic::x86_avx512_cvttsd2si:
2641     case Intrinsic::x86_avx512_cvttsd2si64:
2642       if (ConstantFP *FPOp =
2643               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2644         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2645                                            /*roundTowardZero=*/true, Ty,
2646                                            /*IsSigned*/true);
2647       break;
2648     case Intrinsic::x86_avx512_cvttss2usi:
2649     case Intrinsic::x86_avx512_cvttss2usi64:
2650     case Intrinsic::x86_avx512_cvttsd2usi:
2651     case Intrinsic::x86_avx512_cvttsd2usi64:
2652       if (ConstantFP *FPOp =
2653               dyn_cast_or_null<ConstantFP>(Op->getAggregateElement(0U)))
2654         return ConstantFoldSSEConvertToInt(FPOp->getValueAPF(),
2655                                            /*roundTowardZero=*/true, Ty,
2656                                            /*IsSigned*/false);
2657       break;
2658     }
2659   }
2660   return nullptr;
2661 }
2662 
2663 static APFloat ConstantFoldAMDGCNCubeIntrinsic(Intrinsic::ID IntrinsicID,
2664                                                const APFloat &S0,
2665                                                const APFloat &S1,
2666                                                const APFloat &S2) {
2667   unsigned ID;
2668   const fltSemantics &Sem = S0.getSemantics();
2669   APFloat MA(Sem), SC(Sem), TC(Sem);
2670   if (abs(S2) >= abs(S0) && abs(S2) >= abs(S1)) {
2671     if (S2.isNegative() && S2.isNonZero() && !S2.isNaN()) {
2672       // S2 < 0
2673       ID = 5;
2674       SC = -S0;
2675     } else {
2676       ID = 4;
2677       SC = S0;
2678     }
2679     MA = S2;
2680     TC = -S1;
2681   } else if (abs(S1) >= abs(S0)) {
2682     if (S1.isNegative() && S1.isNonZero() && !S1.isNaN()) {
2683       // S1 < 0
2684       ID = 3;
2685       TC = -S2;
2686     } else {
2687       ID = 2;
2688       TC = S2;
2689     }
2690     MA = S1;
2691     SC = S0;
2692   } else {
2693     if (S0.isNegative() && S0.isNonZero() && !S0.isNaN()) {
2694       // S0 < 0
2695       ID = 1;
2696       SC = S2;
2697     } else {
2698       ID = 0;
2699       SC = -S2;
2700     }
2701     MA = S0;
2702     TC = -S1;
2703   }
2704   switch (IntrinsicID) {
2705   default:
2706     llvm_unreachable("unhandled amdgcn cube intrinsic");
2707   case Intrinsic::amdgcn_cubeid:
2708     return APFloat(Sem, ID);
2709   case Intrinsic::amdgcn_cubema:
2710     return MA + MA;
2711   case Intrinsic::amdgcn_cubesc:
2712     return SC;
2713   case Intrinsic::amdgcn_cubetc:
2714     return TC;
2715   }
2716 }
2717 
2718 static Constant *ConstantFoldScalarCall3(StringRef Name,
2719                                          Intrinsic::ID IntrinsicID,
2720                                          Type *Ty,
2721                                          ArrayRef<Constant *> Operands,
2722                                          const TargetLibraryInfo *TLI,
2723                                          const CallBase *Call) {
2724   assert(Operands.size() == 3 && "Wrong number of operands.");
2725 
2726   if (const auto *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
2727     if (const auto *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
2728       if (const auto *Op3 = dyn_cast<ConstantFP>(Operands[2])) {
2729         switch (IntrinsicID) {
2730         default: break;
2731         case Intrinsic::amdgcn_fma_legacy: {
2732           const APFloat &C1 = Op1->getValueAPF();
2733           const APFloat &C2 = Op2->getValueAPF();
2734           // The legacy behaviour is that multiplying +/- 0.0 by anything, even
2735           // NaN or infinity, gives +0.0.
2736           if (C1.isZero() || C2.isZero()) {
2737             const APFloat &C3 = Op3->getValueAPF();
2738             // It's tempting to just return C3 here, but that would give the
2739             // wrong result if C3 was -0.0.
2740             return ConstantFP::get(Ty->getContext(), APFloat(0.0f) + C3);
2741           }
2742           LLVM_FALLTHROUGH;
2743         }
2744         case Intrinsic::fma:
2745         case Intrinsic::fmuladd: {
2746           APFloat V = Op1->getValueAPF();
2747           V.fusedMultiplyAdd(Op2->getValueAPF(), Op3->getValueAPF(),
2748                              APFloat::rmNearestTiesToEven);
2749           return ConstantFP::get(Ty->getContext(), V);
2750         }
2751         case Intrinsic::amdgcn_cubeid:
2752         case Intrinsic::amdgcn_cubema:
2753         case Intrinsic::amdgcn_cubesc:
2754         case Intrinsic::amdgcn_cubetc: {
2755           APFloat V = ConstantFoldAMDGCNCubeIntrinsic(
2756               IntrinsicID, Op1->getValueAPF(), Op2->getValueAPF(),
2757               Op3->getValueAPF());
2758           return ConstantFP::get(Ty->getContext(), V);
2759         }
2760         }
2761       }
2762     }
2763   }
2764 
2765   if (const auto *Op1 = dyn_cast<ConstantInt>(Operands[0])) {
2766     if (const auto *Op2 = dyn_cast<ConstantInt>(Operands[1])) {
2767       if (const auto *Op3 = dyn_cast<ConstantInt>(Operands[2])) {
2768         switch (IntrinsicID) {
2769         default: break;
2770         case Intrinsic::smul_fix:
2771         case Intrinsic::smul_fix_sat: {
2772           // This code performs rounding towards negative infinity in case the
2773           // result cannot be represented exactly for the given scale. Targets
2774           // that do care about rounding should use a target hook for specifying
2775           // how rounding should be done, and provide their own folding to be
2776           // consistent with rounding. This is the same approach as used by
2777           // DAGTypeLegalizer::ExpandIntRes_MULFIX.
2778           const APInt &Lhs = Op1->getValue();
2779           const APInt &Rhs = Op2->getValue();
2780           unsigned Scale = Op3->getValue().getZExtValue();
2781           unsigned Width = Lhs.getBitWidth();
2782           assert(Scale < Width && "Illegal scale.");
2783           unsigned ExtendedWidth = Width * 2;
2784           APInt Product = (Lhs.sextOrSelf(ExtendedWidth) *
2785                            Rhs.sextOrSelf(ExtendedWidth)).ashr(Scale);
2786           if (IntrinsicID == Intrinsic::smul_fix_sat) {
2787             APInt MaxValue =
2788               APInt::getSignedMaxValue(Width).sextOrSelf(ExtendedWidth);
2789             APInt MinValue =
2790               APInt::getSignedMinValue(Width).sextOrSelf(ExtendedWidth);
2791             Product = APIntOps::smin(Product, MaxValue);
2792             Product = APIntOps::smax(Product, MinValue);
2793           }
2794           return ConstantInt::get(Ty->getContext(),
2795                                   Product.sextOrTrunc(Width));
2796         }
2797         }
2798       }
2799     }
2800   }
2801 
2802   if (IntrinsicID == Intrinsic::fshl || IntrinsicID == Intrinsic::fshr) {
2803     const APInt *C0, *C1, *C2;
2804     if (!getConstIntOrUndef(Operands[0], C0) ||
2805         !getConstIntOrUndef(Operands[1], C1) ||
2806         !getConstIntOrUndef(Operands[2], C2))
2807       return nullptr;
2808 
2809     bool IsRight = IntrinsicID == Intrinsic::fshr;
2810     if (!C2)
2811       return Operands[IsRight ? 1 : 0];
2812     if (!C0 && !C1)
2813       return UndefValue::get(Ty);
2814 
2815     // The shift amount is interpreted as modulo the bitwidth. If the shift
2816     // amount is effectively 0, avoid UB due to oversized inverse shift below.
2817     unsigned BitWidth = C2->getBitWidth();
2818     unsigned ShAmt = C2->urem(BitWidth);
2819     if (!ShAmt)
2820       return Operands[IsRight ? 1 : 0];
2821 
2822     // (C0 << ShlAmt) | (C1 >> LshrAmt)
2823     unsigned LshrAmt = IsRight ? ShAmt : BitWidth - ShAmt;
2824     unsigned ShlAmt = !IsRight ? ShAmt : BitWidth - ShAmt;
2825     if (!C0)
2826       return ConstantInt::get(Ty, C1->lshr(LshrAmt));
2827     if (!C1)
2828       return ConstantInt::get(Ty, C0->shl(ShlAmt));
2829     return ConstantInt::get(Ty, C0->shl(ShlAmt) | C1->lshr(LshrAmt));
2830   }
2831 
2832   return nullptr;
2833 }
2834 
2835 static Constant *ConstantFoldScalarCall(StringRef Name,
2836                                         Intrinsic::ID IntrinsicID,
2837                                         Type *Ty,
2838                                         ArrayRef<Constant *> Operands,
2839                                         const TargetLibraryInfo *TLI,
2840                                         const CallBase *Call) {
2841   if (Operands.size() == 1)
2842     return ConstantFoldScalarCall1(Name, IntrinsicID, Ty, Operands, TLI, Call);
2843 
2844   if (Operands.size() == 2)
2845     return ConstantFoldScalarCall2(Name, IntrinsicID, Ty, Operands, TLI, Call);
2846 
2847   if (Operands.size() == 3)
2848     return ConstantFoldScalarCall3(Name, IntrinsicID, Ty, Operands, TLI, Call);
2849 
2850   return nullptr;
2851 }
2852 
2853 static Constant *ConstantFoldVectorCall(StringRef Name,
2854                                         Intrinsic::ID IntrinsicID,
2855                                         VectorType *VTy,
2856                                         ArrayRef<Constant *> Operands,
2857                                         const DataLayout &DL,
2858                                         const TargetLibraryInfo *TLI,
2859                                         const CallBase *Call) {
2860   // Do not iterate on scalable vector. The number of elements is unknown at
2861   // compile-time.
2862   if (isa<ScalableVectorType>(VTy))
2863     return nullptr;
2864 
2865   auto *FVTy = cast<FixedVectorType>(VTy);
2866 
2867   SmallVector<Constant *, 4> Result(FVTy->getNumElements());
2868   SmallVector<Constant *, 4> Lane(Operands.size());
2869   Type *Ty = FVTy->getElementType();
2870 
2871   switch (IntrinsicID) {
2872   case Intrinsic::masked_load: {
2873     auto *SrcPtr = Operands[0];
2874     auto *Mask = Operands[2];
2875     auto *Passthru = Operands[3];
2876 
2877     Constant *VecData = ConstantFoldLoadFromConstPtr(SrcPtr, FVTy, DL);
2878 
2879     SmallVector<Constant *, 32> NewElements;
2880     for (unsigned I = 0, E = FVTy->getNumElements(); I != E; ++I) {
2881       auto *MaskElt = Mask->getAggregateElement(I);
2882       if (!MaskElt)
2883         break;
2884       auto *PassthruElt = Passthru->getAggregateElement(I);
2885       auto *VecElt = VecData ? VecData->getAggregateElement(I) : nullptr;
2886       if (isa<UndefValue>(MaskElt)) {
2887         if (PassthruElt)
2888           NewElements.push_back(PassthruElt);
2889         else if (VecElt)
2890           NewElements.push_back(VecElt);
2891         else
2892           return nullptr;
2893       }
2894       if (MaskElt->isNullValue()) {
2895         if (!PassthruElt)
2896           return nullptr;
2897         NewElements.push_back(PassthruElt);
2898       } else if (MaskElt->isOneValue()) {
2899         if (!VecElt)
2900           return nullptr;
2901         NewElements.push_back(VecElt);
2902       } else {
2903         return nullptr;
2904       }
2905     }
2906     if (NewElements.size() != FVTy->getNumElements())
2907       return nullptr;
2908     return ConstantVector::get(NewElements);
2909   }
2910   case Intrinsic::arm_mve_vctp8:
2911   case Intrinsic::arm_mve_vctp16:
2912   case Intrinsic::arm_mve_vctp32:
2913   case Intrinsic::arm_mve_vctp64: {
2914     if (auto *Op = dyn_cast<ConstantInt>(Operands[0])) {
2915       unsigned Lanes = FVTy->getNumElements();
2916       uint64_t Limit = Op->getZExtValue();
2917       // vctp64 are currently modelled as returning a v4i1, not a v2i1. Make
2918       // sure we get the limit right in that case and set all relevant lanes.
2919       if (IntrinsicID == Intrinsic::arm_mve_vctp64)
2920         Limit *= 2;
2921 
2922       SmallVector<Constant *, 16> NCs;
2923       for (unsigned i = 0; i < Lanes; i++) {
2924         if (i < Limit)
2925           NCs.push_back(ConstantInt::getTrue(Ty));
2926         else
2927           NCs.push_back(ConstantInt::getFalse(Ty));
2928       }
2929       return ConstantVector::get(NCs);
2930     }
2931     break;
2932   }
2933   case Intrinsic::get_active_lane_mask: {
2934     auto *Op0 = dyn_cast<ConstantInt>(Operands[0]);
2935     auto *Op1 = dyn_cast<ConstantInt>(Operands[1]);
2936     if (Op0 && Op1) {
2937       unsigned Lanes = FVTy->getNumElements();
2938       uint64_t Base = Op0->getZExtValue();
2939       uint64_t Limit = Op1->getZExtValue();
2940 
2941       SmallVector<Constant *, 16> NCs;
2942       for (unsigned i = 0; i < Lanes; i++) {
2943         if (Base + i < Limit)
2944           NCs.push_back(ConstantInt::getTrue(Ty));
2945         else
2946           NCs.push_back(ConstantInt::getFalse(Ty));
2947       }
2948       return ConstantVector::get(NCs);
2949     }
2950     break;
2951   }
2952   default:
2953     break;
2954   }
2955 
2956   for (unsigned I = 0, E = FVTy->getNumElements(); I != E; ++I) {
2957     // Gather a column of constants.
2958     for (unsigned J = 0, JE = Operands.size(); J != JE; ++J) {
2959       // Some intrinsics use a scalar type for certain arguments.
2960       if (hasVectorInstrinsicScalarOpd(IntrinsicID, J)) {
2961         Lane[J] = Operands[J];
2962         continue;
2963       }
2964 
2965       Constant *Agg = Operands[J]->getAggregateElement(I);
2966       if (!Agg)
2967         return nullptr;
2968 
2969       Lane[J] = Agg;
2970     }
2971 
2972     // Use the regular scalar folding to simplify this column.
2973     Constant *Folded =
2974         ConstantFoldScalarCall(Name, IntrinsicID, Ty, Lane, TLI, Call);
2975     if (!Folded)
2976       return nullptr;
2977     Result[I] = Folded;
2978   }
2979 
2980   return ConstantVector::get(Result);
2981 }
2982 
2983 } // end anonymous namespace
2984 
2985 Constant *llvm::ConstantFoldCall(const CallBase *Call, Function *F,
2986                                  ArrayRef<Constant *> Operands,
2987                                  const TargetLibraryInfo *TLI) {
2988   if (Call->isNoBuiltin())
2989     return nullptr;
2990   if (!F->hasName())
2991     return nullptr;
2992   StringRef Name = F->getName();
2993 
2994   Type *Ty = F->getReturnType();
2995 
2996   if (auto *VTy = dyn_cast<VectorType>(Ty))
2997     return ConstantFoldVectorCall(Name, F->getIntrinsicID(), VTy, Operands,
2998                                   F->getParent()->getDataLayout(), TLI, Call);
2999 
3000   return ConstantFoldScalarCall(Name, F->getIntrinsicID(), Ty, Operands, TLI,
3001                                 Call);
3002 }
3003 
3004 bool llvm::isMathLibCallNoop(const CallBase *Call,
3005                              const TargetLibraryInfo *TLI) {
3006   // FIXME: Refactor this code; this duplicates logic in LibCallsShrinkWrap
3007   // (and to some extent ConstantFoldScalarCall).
3008   if (Call->isNoBuiltin() || Call->isStrictFP())
3009     return false;
3010   Function *F = Call->getCalledFunction();
3011   if (!F)
3012     return false;
3013 
3014   LibFunc Func;
3015   if (!TLI || !TLI->getLibFunc(*F, Func))
3016     return false;
3017 
3018   if (Call->getNumArgOperands() == 1) {
3019     if (ConstantFP *OpC = dyn_cast<ConstantFP>(Call->getArgOperand(0))) {
3020       const APFloat &Op = OpC->getValueAPF();
3021       switch (Func) {
3022       case LibFunc_logl:
3023       case LibFunc_log:
3024       case LibFunc_logf:
3025       case LibFunc_log2l:
3026       case LibFunc_log2:
3027       case LibFunc_log2f:
3028       case LibFunc_log10l:
3029       case LibFunc_log10:
3030       case LibFunc_log10f:
3031         return Op.isNaN() || (!Op.isZero() && !Op.isNegative());
3032 
3033       case LibFunc_expl:
3034       case LibFunc_exp:
3035       case LibFunc_expf:
3036         // FIXME: These boundaries are slightly conservative.
3037         if (OpC->getType()->isDoubleTy())
3038           return !(Op < APFloat(-745.0) || Op > APFloat(709.0));
3039         if (OpC->getType()->isFloatTy())
3040           return !(Op < APFloat(-103.0f) || Op > APFloat(88.0f));
3041         break;
3042 
3043       case LibFunc_exp2l:
3044       case LibFunc_exp2:
3045       case LibFunc_exp2f:
3046         // FIXME: These boundaries are slightly conservative.
3047         if (OpC->getType()->isDoubleTy())
3048           return !(Op < APFloat(-1074.0) || Op > APFloat(1023.0));
3049         if (OpC->getType()->isFloatTy())
3050           return !(Op < APFloat(-149.0f) || Op > APFloat(127.0f));
3051         break;
3052 
3053       case LibFunc_sinl:
3054       case LibFunc_sin:
3055       case LibFunc_sinf:
3056       case LibFunc_cosl:
3057       case LibFunc_cos:
3058       case LibFunc_cosf:
3059         return !Op.isInfinity();
3060 
3061       case LibFunc_tanl:
3062       case LibFunc_tan:
3063       case LibFunc_tanf: {
3064         // FIXME: Stop using the host math library.
3065         // FIXME: The computation isn't done in the right precision.
3066         Type *Ty = OpC->getType();
3067         if (Ty->isDoubleTy() || Ty->isFloatTy() || Ty->isHalfTy()) {
3068           double OpV = getValueAsDouble(OpC);
3069           return ConstantFoldFP(tan, OpV, Ty) != nullptr;
3070         }
3071         break;
3072       }
3073 
3074       case LibFunc_asinl:
3075       case LibFunc_asin:
3076       case LibFunc_asinf:
3077       case LibFunc_acosl:
3078       case LibFunc_acos:
3079       case LibFunc_acosf:
3080         return !(Op < APFloat(Op.getSemantics(), "-1") ||
3081                  Op > APFloat(Op.getSemantics(), "1"));
3082 
3083       case LibFunc_sinh:
3084       case LibFunc_cosh:
3085       case LibFunc_sinhf:
3086       case LibFunc_coshf:
3087       case LibFunc_sinhl:
3088       case LibFunc_coshl:
3089         // FIXME: These boundaries are slightly conservative.
3090         if (OpC->getType()->isDoubleTy())
3091           return !(Op < APFloat(-710.0) || Op > APFloat(710.0));
3092         if (OpC->getType()->isFloatTy())
3093           return !(Op < APFloat(-89.0f) || Op > APFloat(89.0f));
3094         break;
3095 
3096       case LibFunc_sqrtl:
3097       case LibFunc_sqrt:
3098       case LibFunc_sqrtf:
3099         return Op.isNaN() || Op.isZero() || !Op.isNegative();
3100 
3101       // FIXME: Add more functions: sqrt_finite, atanh, expm1, log1p,
3102       // maybe others?
3103       default:
3104         break;
3105       }
3106     }
3107   }
3108 
3109   if (Call->getNumArgOperands() == 2) {
3110     ConstantFP *Op0C = dyn_cast<ConstantFP>(Call->getArgOperand(0));
3111     ConstantFP *Op1C = dyn_cast<ConstantFP>(Call->getArgOperand(1));
3112     if (Op0C && Op1C) {
3113       const APFloat &Op0 = Op0C->getValueAPF();
3114       const APFloat &Op1 = Op1C->getValueAPF();
3115 
3116       switch (Func) {
3117       case LibFunc_powl:
3118       case LibFunc_pow:
3119       case LibFunc_powf: {
3120         // FIXME: Stop using the host math library.
3121         // FIXME: The computation isn't done in the right precision.
3122         Type *Ty = Op0C->getType();
3123         if (Ty->isDoubleTy() || Ty->isFloatTy() || Ty->isHalfTy()) {
3124           if (Ty == Op1C->getType()) {
3125             double Op0V = getValueAsDouble(Op0C);
3126             double Op1V = getValueAsDouble(Op1C);
3127             return ConstantFoldBinaryFP(pow, Op0V, Op1V, Ty) != nullptr;
3128           }
3129         }
3130         break;
3131       }
3132 
3133       case LibFunc_fmodl:
3134       case LibFunc_fmod:
3135       case LibFunc_fmodf:
3136       case LibFunc_remainderl:
3137       case LibFunc_remainder:
3138       case LibFunc_remainderf:
3139         return Op0.isNaN() || Op1.isNaN() ||
3140                (!Op0.isInfinity() && !Op1.isZero());
3141 
3142       default:
3143         break;
3144       }
3145     }
3146   }
3147 
3148   return false;
3149 }
3150 
3151 void TargetFolder::anchor() {}
3152