1 //===- InstCombineCompares.cpp --------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the visitICmp and visitFCmp functions.
12 //===----------------------------------------------------------------------===//
14 #include "InstCombine.h"
15 #include "llvm/Analysis/ConstantFolding.h"
16 #include "llvm/Analysis/InstructionSimplify.h"
17 #include "llvm/Analysis/MemoryBuiltins.h"
18 #include "llvm/IR/ConstantRange.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/GetElementPtrTypeIterator.h"
21 #include "llvm/IR/IntrinsicInst.h"
22 #include "llvm/IR/PatternMatch.h"
23 #include "llvm/Target/TargetLibraryInfo.h"
25 using namespace PatternMatch;
27 #define DEBUG_TYPE "instcombine"
29 static ConstantInt *getOne(Constant *C) {
30 return ConstantInt::get(cast<IntegerType>(C->getType()), 1);
33 static ConstantInt *ExtractElement(Constant *V, Constant *Idx) {
34 return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
37 static bool HasAddOverflow(ConstantInt *Result,
38 ConstantInt *In1, ConstantInt *In2,
41 return Result->getValue().ult(In1->getValue());
43 if (In2->isNegative())
44 return Result->getValue().sgt(In1->getValue());
45 return Result->getValue().slt(In1->getValue());
48 /// AddWithOverflow - Compute Result = In1+In2, returning true if the result
49 /// overflowed for this type.
50 static bool AddWithOverflow(Constant *&Result, Constant *In1,
51 Constant *In2, bool IsSigned = false) {
52 Result = ConstantExpr::getAdd(In1, In2);
54 if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
55 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
56 Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
57 if (HasAddOverflow(ExtractElement(Result, Idx),
58 ExtractElement(In1, Idx),
59 ExtractElement(In2, Idx),
66 return HasAddOverflow(cast<ConstantInt>(Result),
67 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
71 static bool HasSubOverflow(ConstantInt *Result,
72 ConstantInt *In1, ConstantInt *In2,
75 return Result->getValue().ugt(In1->getValue());
77 if (In2->isNegative())
78 return Result->getValue().slt(In1->getValue());
80 return Result->getValue().sgt(In1->getValue());
83 /// SubWithOverflow - Compute Result = In1-In2, returning true if the result
84 /// overflowed for this type.
85 static bool SubWithOverflow(Constant *&Result, Constant *In1,
86 Constant *In2, bool IsSigned = false) {
87 Result = ConstantExpr::getSub(In1, In2);
89 if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
90 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
91 Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
92 if (HasSubOverflow(ExtractElement(Result, Idx),
93 ExtractElement(In1, Idx),
94 ExtractElement(In2, Idx),
101 return HasSubOverflow(cast<ConstantInt>(Result),
102 cast<ConstantInt>(In1), cast<ConstantInt>(In2),
106 /// isSignBitCheck - Given an exploded icmp instruction, return true if the
107 /// comparison only checks the sign bit. If it only checks the sign bit, set
108 /// TrueIfSigned if the result of the comparison is true when the input value is
110 static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
111 bool &TrueIfSigned) {
113 case ICmpInst::ICMP_SLT: // True if LHS s< 0
115 return RHS->isZero();
116 case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
118 return RHS->isAllOnesValue();
119 case ICmpInst::ICMP_SGT: // True if LHS s> -1
120 TrueIfSigned = false;
121 return RHS->isAllOnesValue();
122 case ICmpInst::ICMP_UGT:
123 // True if LHS u> RHS and RHS == high-bit-mask - 1
125 return RHS->isMaxValue(true);
126 case ICmpInst::ICMP_UGE:
127 // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
129 return RHS->getValue().isSignBit();
135 /// Returns true if the exploded icmp can be expressed as a signed comparison
136 /// to zero and updates the predicate accordingly.
137 /// The signedness of the comparison is preserved.
138 static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) {
139 if (!ICmpInst::isSigned(pred))
143 return ICmpInst::isRelational(pred);
146 if (pred == ICmpInst::ICMP_SLT) {
147 pred = ICmpInst::ICMP_SLE;
150 } else if (RHS->isAllOnesValue()) {
151 if (pred == ICmpInst::ICMP_SGT) {
152 pred = ICmpInst::ICMP_SGE;
160 // isHighOnes - Return true if the constant is of the form 1+0+.
161 // This is the same as lowones(~X).
162 static bool isHighOnes(const ConstantInt *CI) {
163 return (~CI->getValue() + 1).isPowerOf2();
166 /// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
167 /// set of known zero and one bits, compute the maximum and minimum values that
168 /// could have the specified known zero and known one bits, returning them in
170 static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
171 const APInt& KnownOne,
172 APInt& Min, APInt& Max) {
173 assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
174 KnownZero.getBitWidth() == Min.getBitWidth() &&
175 KnownZero.getBitWidth() == Max.getBitWidth() &&
176 "KnownZero, KnownOne and Min, Max must have equal bitwidth.");
177 APInt UnknownBits = ~(KnownZero|KnownOne);
179 // The minimum value is when all unknown bits are zeros, EXCEPT for the sign
180 // bit if it is unknown.
182 Max = KnownOne|UnknownBits;
184 if (UnknownBits.isNegative()) { // Sign bit is unknown
185 Min.setBit(Min.getBitWidth()-1);
186 Max.clearBit(Max.getBitWidth()-1);
190 // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
191 // a set of known zero and one bits, compute the maximum and minimum values that
192 // could have the specified known zero and known one bits, returning them in
194 static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
195 const APInt &KnownOne,
196 APInt &Min, APInt &Max) {
197 assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
198 KnownZero.getBitWidth() == Min.getBitWidth() &&
199 KnownZero.getBitWidth() == Max.getBitWidth() &&
200 "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
201 APInt UnknownBits = ~(KnownZero|KnownOne);
203 // The minimum value is when the unknown bits are all zeros.
205 // The maximum value is when the unknown bits are all ones.
206 Max = KnownOne|UnknownBits;
211 /// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
212 /// cmp pred (load (gep GV, ...)), cmpcst
213 /// where GV is a global variable with a constant initializer. Try to simplify
214 /// this into some simple computation that does not need the load. For example
215 /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
217 /// If AndCst is non-null, then the loaded value is masked with that constant
218 /// before doing the comparison. This handles cases like "A[i]&4 == 0".
219 Instruction *InstCombiner::
220 FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
221 CmpInst &ICI, ConstantInt *AndCst) {
222 // We need TD information to know the pointer size unless this is inbounds.
223 if (!GEP->isInBounds() && !DL)
226 Constant *Init = GV->getInitializer();
227 if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
230 uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
231 if (ArrayElementCount > 1024) return nullptr; // Don't blow up on huge arrays.
233 // There are many forms of this optimization we can handle, for now, just do
234 // the simple index into a single-dimensional array.
236 // Require: GEP GV, 0, i {{, constant indices}}
237 if (GEP->getNumOperands() < 3 ||
238 !isa<ConstantInt>(GEP->getOperand(1)) ||
239 !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
240 isa<Constant>(GEP->getOperand(2)))
243 // Check that indices after the variable are constants and in-range for the
244 // type they index. Collect the indices. This is typically for arrays of
246 SmallVector<unsigned, 4> LaterIndices;
248 Type *EltTy = Init->getType()->getArrayElementType();
249 for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
250 ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
251 if (!Idx) return nullptr; // Variable index.
253 uint64_t IdxVal = Idx->getZExtValue();
254 if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index.
256 if (StructType *STy = dyn_cast<StructType>(EltTy))
257 EltTy = STy->getElementType(IdxVal);
258 else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
259 if (IdxVal >= ATy->getNumElements()) return nullptr;
260 EltTy = ATy->getElementType();
262 return nullptr; // Unknown type.
265 LaterIndices.push_back(IdxVal);
268 enum { Overdefined = -3, Undefined = -2 };
270 // Variables for our state machines.
272 // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
273 // "i == 47 | i == 87", where 47 is the first index the condition is true for,
274 // and 87 is the second (and last) index. FirstTrueElement is -2 when
275 // undefined, otherwise set to the first true element. SecondTrueElement is
276 // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
277 int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
279 // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
280 // form "i != 47 & i != 87". Same state transitions as for true elements.
281 int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
283 /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
284 /// define a state machine that triggers for ranges of values that the index
285 /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
286 /// This is -2 when undefined, -3 when overdefined, and otherwise the last
287 /// index in the range (inclusive). We use -2 for undefined here because we
288 /// use relative comparisons and don't want 0-1 to match -1.
289 int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
291 // MagicBitvector - This is a magic bitvector where we set a bit if the
292 // comparison is true for element 'i'. If there are 64 elements or less in
293 // the array, this will fully represent all the comparison results.
294 uint64_t MagicBitvector = 0;
297 // Scan the array and see if one of our patterns matches.
298 Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
299 for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
300 Constant *Elt = Init->getAggregateElement(i);
301 if (!Elt) return nullptr;
303 // If this is indexing an array of structures, get the structure element.
304 if (!LaterIndices.empty())
305 Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
307 // If the element is masked, handle it.
308 if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
310 // Find out if the comparison would be true or false for the i'th element.
311 Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
312 CompareRHS, DL, TLI);
313 // If the result is undef for this element, ignore it.
314 if (isa<UndefValue>(C)) {
315 // Extend range state machines to cover this element in case there is an
316 // undef in the middle of the range.
317 if (TrueRangeEnd == (int)i-1)
319 if (FalseRangeEnd == (int)i-1)
324 // If we can't compute the result for any of the elements, we have to give
325 // up evaluating the entire conditional.
326 if (!isa<ConstantInt>(C)) return nullptr;
328 // Otherwise, we know if the comparison is true or false for this element,
329 // update our state machines.
330 bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
332 // State machine for single/double/range index comparison.
334 // Update the TrueElement state machine.
335 if (FirstTrueElement == Undefined)
336 FirstTrueElement = TrueRangeEnd = i; // First true element.
338 // Update double-compare state machine.
339 if (SecondTrueElement == Undefined)
340 SecondTrueElement = i;
342 SecondTrueElement = Overdefined;
344 // Update range state machine.
345 if (TrueRangeEnd == (int)i-1)
348 TrueRangeEnd = Overdefined;
351 // Update the FalseElement state machine.
352 if (FirstFalseElement == Undefined)
353 FirstFalseElement = FalseRangeEnd = i; // First false element.
355 // Update double-compare state machine.
356 if (SecondFalseElement == Undefined)
357 SecondFalseElement = i;
359 SecondFalseElement = Overdefined;
361 // Update range state machine.
362 if (FalseRangeEnd == (int)i-1)
365 FalseRangeEnd = Overdefined;
370 // If this element is in range, update our magic bitvector.
371 if (i < 64 && IsTrueForElt)
372 MagicBitvector |= 1ULL << i;
374 // If all of our states become overdefined, bail out early. Since the
375 // predicate is expensive, only check it every 8 elements. This is only
376 // really useful for really huge arrays.
377 if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
378 SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
379 FalseRangeEnd == Overdefined)
383 // Now that we've scanned the entire array, emit our new comparison(s). We
384 // order the state machines in complexity of the generated code.
385 Value *Idx = GEP->getOperand(2);
387 // If the index is larger than the pointer size of the target, truncate the
388 // index down like the GEP would do implicitly. We don't have to do this for
389 // an inbounds GEP because the index can't be out of range.
390 if (!GEP->isInBounds()) {
391 Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
392 unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
393 if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize)
394 Idx = Builder->CreateTrunc(Idx, IntPtrTy);
397 // If the comparison is only true for one or two elements, emit direct
399 if (SecondTrueElement != Overdefined) {
400 // None true -> false.
401 if (FirstTrueElement == Undefined)
402 return ReplaceInstUsesWith(ICI, Builder->getFalse());
404 Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
406 // True for one element -> 'i == 47'.
407 if (SecondTrueElement == Undefined)
408 return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
410 // True for two elements -> 'i == 47 | i == 72'.
411 Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
412 Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
413 Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
414 return BinaryOperator::CreateOr(C1, C2);
417 // If the comparison is only false for one or two elements, emit direct
419 if (SecondFalseElement != Overdefined) {
420 // None false -> true.
421 if (FirstFalseElement == Undefined)
422 return ReplaceInstUsesWith(ICI, Builder->getTrue());
424 Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
426 // False for one element -> 'i != 47'.
427 if (SecondFalseElement == Undefined)
428 return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
430 // False for two elements -> 'i != 47 & i != 72'.
431 Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
432 Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
433 Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
434 return BinaryOperator::CreateAnd(C1, C2);
437 // If the comparison can be replaced with a range comparison for the elements
438 // where it is true, emit the range check.
439 if (TrueRangeEnd != Overdefined) {
440 assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
442 // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
443 if (FirstTrueElement) {
444 Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
445 Idx = Builder->CreateAdd(Idx, Offs);
448 Value *End = ConstantInt::get(Idx->getType(),
449 TrueRangeEnd-FirstTrueElement+1);
450 return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
453 // False range check.
454 if (FalseRangeEnd != Overdefined) {
455 assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
456 // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
457 if (FirstFalseElement) {
458 Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
459 Idx = Builder->CreateAdd(Idx, Offs);
462 Value *End = ConstantInt::get(Idx->getType(),
463 FalseRangeEnd-FirstFalseElement);
464 return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
468 // If a magic bitvector captures the entire comparison state
469 // of this load, replace it with computation that does:
470 // ((magic_cst >> i) & 1) != 0
474 // Look for an appropriate type:
475 // - The type of Idx if the magic fits
476 // - The smallest fitting legal type if we have a DataLayout
478 if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
481 Ty = DL->getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
482 else if (ArrayElementCount <= 32)
483 Ty = Type::getInt32Ty(Init->getContext());
486 Value *V = Builder->CreateIntCast(Idx, Ty, false);
487 V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
488 V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
489 return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
497 /// EvaluateGEPOffsetExpression - Return a value that can be used to compare
498 /// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
499 /// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
500 /// be complex, and scales are involved. The above expression would also be
501 /// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
502 /// This later form is less amenable to optimization though, and we are allowed
503 /// to generate the first by knowing that pointer arithmetic doesn't overflow.
505 /// If we can't emit an optimized form for this expression, this returns null.
507 static Value *EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC) {
508 const DataLayout &DL = *IC.getDataLayout();
509 gep_type_iterator GTI = gep_type_begin(GEP);
511 // Check to see if this gep only has a single variable index. If so, and if
512 // any constant indices are a multiple of its scale, then we can compute this
513 // in terms of the scale of the variable index. For example, if the GEP
514 // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
515 // because the expression will cross zero at the same point.
516 unsigned i, e = GEP->getNumOperands();
518 for (i = 1; i != e; ++i, ++GTI) {
519 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
520 // Compute the aggregate offset of constant indices.
521 if (CI->isZero()) continue;
523 // Handle a struct index, which adds its field offset to the pointer.
524 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
525 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
527 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
528 Offset += Size*CI->getSExtValue();
531 // Found our variable index.
536 // If there are no variable indices, we must have a constant offset, just
537 // evaluate it the general way.
538 if (i == e) return nullptr;
540 Value *VariableIdx = GEP->getOperand(i);
541 // Determine the scale factor of the variable element. For example, this is
542 // 4 if the variable index is into an array of i32.
543 uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
545 // Verify that there are no other variable indices. If so, emit the hard way.
546 for (++i, ++GTI; i != e; ++i, ++GTI) {
547 ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
548 if (!CI) return nullptr;
550 // Compute the aggregate offset of constant indices.
551 if (CI->isZero()) continue;
553 // Handle a struct index, which adds its field offset to the pointer.
554 if (StructType *STy = dyn_cast<StructType>(*GTI)) {
555 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
557 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
558 Offset += Size*CI->getSExtValue();
564 // Okay, we know we have a single variable index, which must be a
565 // pointer/array/vector index. If there is no offset, life is simple, return
567 Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
568 unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
570 // Cast to intptrty in case a truncation occurs. If an extension is needed,
571 // we don't need to bother extending: the extension won't affect where the
572 // computation crosses zero.
573 if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) {
574 VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy);
579 // Otherwise, there is an index. The computation we will do will be modulo
580 // the pointer size, so get it.
581 uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
583 Offset &= PtrSizeMask;
584 VariableScale &= PtrSizeMask;
586 // To do this transformation, any constant index must be a multiple of the
587 // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
588 // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
589 // multiple of the variable scale.
590 int64_t NewOffs = Offset / (int64_t)VariableScale;
591 if (Offset != NewOffs*(int64_t)VariableScale)
594 // Okay, we can do this evaluation. Start by converting the index to intptr.
595 if (VariableIdx->getType() != IntPtrTy)
596 VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy,
598 Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
599 return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset");
602 /// FoldGEPICmp - Fold comparisons between a GEP instruction and something
603 /// else. At this point we know that the GEP is on the LHS of the comparison.
604 Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
605 ICmpInst::Predicate Cond,
607 // Don't transform signed compares of GEPs into index compares. Even if the
608 // GEP is inbounds, the final add of the base pointer can have signed overflow
609 // and would change the result of the icmp.
610 // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
611 // the maximum signed value for the pointer type.
612 if (ICmpInst::isSigned(Cond))
615 // Look through bitcasts and addrspacecasts. We do not however want to remove
617 if (!isa<GetElementPtrInst>(RHS))
618 RHS = RHS->stripPointerCasts();
620 Value *PtrBase = GEPLHS->getOperand(0);
621 if (DL && PtrBase == RHS && GEPLHS->isInBounds()) {
622 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
623 // This transformation (ignoring the base and scales) is valid because we
624 // know pointers can't overflow since the gep is inbounds. See if we can
625 // output an optimized form.
626 Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, *this);
628 // If not, synthesize the offset the hard way.
630 Offset = EmitGEPOffset(GEPLHS);
631 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
632 Constant::getNullValue(Offset->getType()));
633 } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
634 // If the base pointers are different, but the indices are the same, just
635 // compare the base pointer.
636 if (PtrBase != GEPRHS->getOperand(0)) {
637 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
638 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
639 GEPRHS->getOperand(0)->getType();
641 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
642 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
643 IndicesTheSame = false;
647 // If all indices are the same, just compare the base pointers.
649 return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
651 // If we're comparing GEPs with two base pointers that only differ in type
652 // and both GEPs have only constant indices or just one use, then fold
653 // the compare with the adjusted indices.
654 if (DL && GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
655 (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
656 (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
657 PtrBase->stripPointerCasts() ==
658 GEPRHS->getOperand(0)->stripPointerCasts()) {
659 Value *LOffset = EmitGEPOffset(GEPLHS);
660 Value *ROffset = EmitGEPOffset(GEPRHS);
662 // If we looked through an addrspacecast between different sized address
663 // spaces, the LHS and RHS pointers are different sized
664 // integers. Truncate to the smaller one.
665 Type *LHSIndexTy = LOffset->getType();
666 Type *RHSIndexTy = ROffset->getType();
667 if (LHSIndexTy != RHSIndexTy) {
668 if (LHSIndexTy->getPrimitiveSizeInBits() <
669 RHSIndexTy->getPrimitiveSizeInBits()) {
670 ROffset = Builder->CreateTrunc(ROffset, LHSIndexTy);
672 LOffset = Builder->CreateTrunc(LOffset, RHSIndexTy);
675 Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond),
677 return ReplaceInstUsesWith(I, Cmp);
680 // Otherwise, the base pointers are different and the indices are
681 // different, bail out.
685 // If one of the GEPs has all zero indices, recurse.
686 if (GEPLHS->hasAllZeroIndices())
687 return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
688 ICmpInst::getSwappedPredicate(Cond), I);
690 // If the other GEP has all zero indices, recurse.
691 if (GEPRHS->hasAllZeroIndices())
692 return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
694 bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
695 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
696 // If the GEPs only differ by one index, compare it.
697 unsigned NumDifferences = 0; // Keep track of # differences.
698 unsigned DiffOperand = 0; // The operand that differs.
699 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
700 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
701 if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
702 GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
703 // Irreconcilable differences.
707 if (NumDifferences++) break;
712 if (NumDifferences == 0) // SAME GEP?
713 return ReplaceInstUsesWith(I, // No comparison is needed here.
714 Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond)));
716 else if (NumDifferences == 1 && GEPsInBounds) {
717 Value *LHSV = GEPLHS->getOperand(DiffOperand);
718 Value *RHSV = GEPRHS->getOperand(DiffOperand);
719 // Make sure we do a signed comparison here.
720 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
724 // Only lower this if the icmp is the only user of the GEP or if we expect
725 // the result to fold to a constant!
728 (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
729 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
730 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
731 Value *L = EmitGEPOffset(GEPLHS);
732 Value *R = EmitGEPOffset(GEPRHS);
733 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
739 /// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
740 Instruction *InstCombiner::FoldICmpAddOpCst(Instruction &ICI,
741 Value *X, ConstantInt *CI,
742 ICmpInst::Predicate Pred) {
743 // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
744 // so the values can never be equal. Similarly for all other "or equals"
747 // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
748 // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
749 // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
750 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
752 ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI);
753 return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
756 // (X+1) >u X --> X <u (0-1) --> X != 255
757 // (X+2) >u X --> X <u (0-2) --> X <u 254
758 // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
759 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
760 return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
762 unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
763 ConstantInt *SMax = ConstantInt::get(X->getContext(),
764 APInt::getSignedMaxValue(BitWidth));
766 // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
767 // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
768 // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
769 // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
770 // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
771 // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
772 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
773 return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
775 // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
776 // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
777 // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
778 // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
779 // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
780 // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
782 assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
783 Constant *C = Builder->getInt(CI->getValue()-1);
784 return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
787 /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
788 /// and CmpRHS are both known to be integer constants.
789 Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
790 ConstantInt *DivRHS) {
791 ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
792 const APInt &CmpRHSV = CmpRHS->getValue();
794 // FIXME: If the operand types don't match the type of the divide
795 // then don't attempt this transform. The code below doesn't have the
796 // logic to deal with a signed divide and an unsigned compare (and
797 // vice versa). This is because (x /s C1) <s C2 produces different
798 // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
799 // (x /u C1) <u C2. Simply casting the operands and result won't
800 // work. :( The if statement below tests that condition and bails
802 bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
803 if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
805 if (DivRHS->isZero())
806 return nullptr; // The ProdOV computation fails on divide by zero.
807 if (DivIsSigned && DivRHS->isAllOnesValue())
808 return nullptr; // The overflow computation also screws up here
809 if (DivRHS->isOne()) {
810 // This eliminates some funny cases with INT_MIN.
811 ICI.setOperand(0, DivI->getOperand(0)); // X/1 == X.
815 // Compute Prod = CI * DivRHS. We are essentially solving an equation
816 // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
817 // C2 (CI). By solving for X we can turn this into a range check
818 // instead of computing a divide.
819 Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
821 // Determine if the product overflows by seeing if the product is
822 // not equal to the divide. Make sure we do the same kind of divide
823 // as in the LHS instruction that we're folding.
824 bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
825 ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
827 // Get the ICmp opcode
828 ICmpInst::Predicate Pred = ICI.getPredicate();
830 /// If the division is known to be exact, then there is no remainder from the
831 /// divide, so the covered range size is unit, otherwise it is the divisor.
832 ConstantInt *RangeSize = DivI->isExact() ? getOne(Prod) : DivRHS;
834 // Figure out the interval that is being checked. For example, a comparison
835 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
836 // Compute this interval based on the constants involved and the signedness of
837 // the compare/divide. This computes a half-open interval, keeping track of
838 // whether either value in the interval overflows. After analysis each
839 // overflow variable is set to 0 if it's corresponding bound variable is valid
840 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
841 int LoOverflow = 0, HiOverflow = 0;
842 Constant *LoBound = nullptr, *HiBound = nullptr;
844 if (!DivIsSigned) { // udiv
845 // e.g. X/5 op 3 --> [15, 20)
847 HiOverflow = LoOverflow = ProdOV;
849 // If this is not an exact divide, then many values in the range collapse
850 // to the same result value.
851 HiOverflow = AddWithOverflow(HiBound, LoBound, RangeSize, false);
854 } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
855 if (CmpRHSV == 0) { // (X / pos) op 0
856 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
857 LoBound = ConstantExpr::getNeg(SubOne(RangeSize));
859 } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
860 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
861 HiOverflow = LoOverflow = ProdOV;
863 HiOverflow = AddWithOverflow(HiBound, Prod, RangeSize, true);
864 } else { // (X / pos) op neg
865 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
866 HiBound = AddOne(Prod);
867 LoOverflow = HiOverflow = ProdOV ? -1 : 0;
869 ConstantInt *DivNeg =cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
870 LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
873 } else if (DivRHS->isNegative()) { // Divisor is < 0.
875 RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
876 if (CmpRHSV == 0) { // (X / neg) op 0
877 // e.g. X/-5 op 0 --> [-4, 5)
878 LoBound = AddOne(RangeSize);
879 HiBound = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
880 if (HiBound == DivRHS) { // -INTMIN = INTMIN
881 HiOverflow = 1; // [INTMIN+1, overflow)
882 HiBound = nullptr; // e.g. X/INTMIN = 0 --> X > INTMIN
884 } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
885 // e.g. X/-5 op 3 --> [-19, -14)
886 HiBound = AddOne(Prod);
887 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
889 LoOverflow = AddWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
890 } else { // (X / neg) op neg
891 LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
892 LoOverflow = HiOverflow = ProdOV;
894 HiOverflow = SubWithOverflow(HiBound, Prod, RangeSize, true);
897 // Dividing by a negative swaps the condition. LT <-> GT
898 Pred = ICmpInst::getSwappedPredicate(Pred);
901 Value *X = DivI->getOperand(0);
903 default: llvm_unreachable("Unhandled icmp opcode!");
904 case ICmpInst::ICMP_EQ:
905 if (LoOverflow && HiOverflow)
906 return ReplaceInstUsesWith(ICI, Builder->getFalse());
908 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
909 ICmpInst::ICMP_UGE, X, LoBound);
911 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
912 ICmpInst::ICMP_ULT, X, HiBound);
913 return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
915 case ICmpInst::ICMP_NE:
916 if (LoOverflow && HiOverflow)
917 return ReplaceInstUsesWith(ICI, Builder->getTrue());
919 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
920 ICmpInst::ICMP_ULT, X, LoBound);
922 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
923 ICmpInst::ICMP_UGE, X, HiBound);
924 return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
925 DivIsSigned, false));
926 case ICmpInst::ICMP_ULT:
927 case ICmpInst::ICMP_SLT:
928 if (LoOverflow == +1) // Low bound is greater than input range.
929 return ReplaceInstUsesWith(ICI, Builder->getTrue());
930 if (LoOverflow == -1) // Low bound is less than input range.
931 return ReplaceInstUsesWith(ICI, Builder->getFalse());
932 return new ICmpInst(Pred, X, LoBound);
933 case ICmpInst::ICMP_UGT:
934 case ICmpInst::ICMP_SGT:
935 if (HiOverflow == +1) // High bound greater than input range.
936 return ReplaceInstUsesWith(ICI, Builder->getFalse());
937 if (HiOverflow == -1) // High bound less than input range.
938 return ReplaceInstUsesWith(ICI, Builder->getTrue());
939 if (Pred == ICmpInst::ICMP_UGT)
940 return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
941 return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
945 /// FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)".
946 Instruction *InstCombiner::FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *Shr,
947 ConstantInt *ShAmt) {
948 const APInt &CmpRHSV = cast<ConstantInt>(ICI.getOperand(1))->getValue();
950 // Check that the shift amount is in range. If not, don't perform
951 // undefined shifts. When the shift is visited it will be
953 uint32_t TypeBits = CmpRHSV.getBitWidth();
954 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
955 if (ShAmtVal >= TypeBits || ShAmtVal == 0)
958 if (!ICI.isEquality()) {
959 // If we have an unsigned comparison and an ashr, we can't simplify this.
960 // Similarly for signed comparisons with lshr.
961 if (ICI.isSigned() != (Shr->getOpcode() == Instruction::AShr))
964 // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv
965 // by a power of 2. Since we already have logic to simplify these,
966 // transform to div and then simplify the resultant comparison.
967 if (Shr->getOpcode() == Instruction::AShr &&
968 (!Shr->isExact() || ShAmtVal == TypeBits - 1))
971 // Revisit the shift (to delete it).
975 ConstantInt::get(Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal));
978 Shr->getOpcode() == Instruction::AShr ?
979 Builder->CreateSDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()) :
980 Builder->CreateUDiv(Shr->getOperand(0), DivCst, "", Shr->isExact());
982 ICI.setOperand(0, Tmp);
984 // If the builder folded the binop, just return it.
985 BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp);
989 // Otherwise, fold this div/compare.
990 assert(TheDiv->getOpcode() == Instruction::SDiv ||
991 TheDiv->getOpcode() == Instruction::UDiv);
993 Instruction *Res = FoldICmpDivCst(ICI, TheDiv, cast<ConstantInt>(DivCst));
994 assert(Res && "This div/cst should have folded!");
999 // If we are comparing against bits always shifted out, the
1000 // comparison cannot succeed.
1001 APInt Comp = CmpRHSV << ShAmtVal;
1002 ConstantInt *ShiftedCmpRHS = Builder->getInt(Comp);
1003 if (Shr->getOpcode() == Instruction::LShr)
1004 Comp = Comp.lshr(ShAmtVal);
1006 Comp = Comp.ashr(ShAmtVal);
1008 if (Comp != CmpRHSV) { // Comparing against a bit that we know is zero.
1009 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1010 Constant *Cst = Builder->getInt1(IsICMP_NE);
1011 return ReplaceInstUsesWith(ICI, Cst);
1014 // Otherwise, check to see if the bits shifted out are known to be zero.
1015 // If so, we can compare against the unshifted value:
1016 // (X & 4) >> 1 == 2 --> (X & 4) == 4.
1017 if (Shr->hasOneUse() && Shr->isExact())
1018 return new ICmpInst(ICI.getPredicate(), Shr->getOperand(0), ShiftedCmpRHS);
1020 if (Shr->hasOneUse()) {
1021 // Otherwise strength reduce the shift into an and.
1022 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
1023 Constant *Mask = Builder->getInt(Val);
1025 Value *And = Builder->CreateAnd(Shr->getOperand(0),
1026 Mask, Shr->getName()+".mask");
1027 return new ICmpInst(ICI.getPredicate(), And, ShiftedCmpRHS);
1032 /// FoldICmpCstShrCst - Handle "(icmp eq/ne (ashr/lshr const2, A), const1)" ->
1033 /// (icmp eq/ne A, Log2(const2/const1)) ->
1034 /// (icmp eq/ne A, Log2(const2) - Log2(const1)).
1035 Instruction *InstCombiner::FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,
1038 assert(I.isEquality() && "Cannot fold icmp gt/lt");
1040 auto getConstant = [&I, this](bool IsTrue) {
1041 if (I.getPredicate() == I.ICMP_NE)
1043 return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), IsTrue));
1046 auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1047 if (I.getPredicate() == I.ICMP_NE)
1048 Pred = CmpInst::getInversePredicate(Pred);
1049 return new ICmpInst(Pred, LHS, RHS);
1052 APInt AP1 = CI1->getValue();
1053 APInt AP2 = CI2->getValue();
1057 // Both Constants are 0.
1058 return getConstant(true);
1061 if (cast<BinaryOperator>(Op)->isExact())
1062 return getConstant(false);
1064 if (AP2.isNegative()) {
1065 // MSB is set, so a lshr with a large enough 'A' would be undefined.
1066 return getConstant(false);
1069 // 'A' must be large enough to shift out the highest set bit.
1070 return getICmp(I.ICMP_UGT, A,
1071 ConstantInt::get(A->getType(), AP2.logBase2()));
1075 // Shifting 0 by any value gives 0.
1076 return getConstant(false);
1079 bool IsAShr = isa<AShrOperator>(Op);
1081 if (AP1.isAllOnesValue() && IsAShr) {
1082 // Arithmatic shift of -1 is always -1.
1083 return getConstant(true);
1085 return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1088 bool IsNegative = false;
1090 if (AP1.isNegative() != AP2.isNegative()) {
1091 // Arithmetic shift will never change the sign.
1092 return getConstant(false);
1094 // Both the constants are negative, take their positive to calculate log.
1095 if (AP1.isNegative()) {
1097 // Right-shifting won't increase the magnitude.
1098 return getConstant(false);
1103 if (!IsNegative && AP1.ugt(AP2))
1104 // Right-shifting will not increase the value.
1105 return getConstant(false);
1107 // Get the distance between the highest bit that's set.
1110 // Get the ones' complement of AP2 and AP1 when computing the distance.
1111 Shift = (~AP2).logBase2() - (~AP1).logBase2();
1113 Shift = AP2.logBase2() - AP1.logBase2();
1115 if (IsAShr ? AP1 == AP2.ashr(Shift) : AP1 == AP2.lshr(Shift))
1116 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1118 // Shifting const2 will never be equal to const1.
1119 return getConstant(false);
1122 /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
1124 Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
1127 const APInt &RHSV = RHS->getValue();
1129 switch (LHSI->getOpcode()) {
1130 case Instruction::Trunc:
1131 if (ICI.isEquality() && LHSI->hasOneUse()) {
1132 // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
1133 // of the high bits truncated out of x are known.
1134 unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
1135 SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
1136 APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
1137 computeKnownBits(LHSI->getOperand(0), KnownZero, KnownOne, 0, &ICI);
1139 // If all the high bits are known, we can do this xform.
1140 if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
1141 // Pull in the high bits from known-ones set.
1142 APInt NewRHS = RHS->getValue().zext(SrcBits);
1143 NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits);
1144 return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1145 Builder->getInt(NewRHS));
1150 case Instruction::Xor: // (icmp pred (xor X, XorCst), CI)
1151 if (ConstantInt *XorCst = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
1152 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
1154 if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
1155 (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
1156 Value *CompareVal = LHSI->getOperand(0);
1158 // If the sign bit of the XorCst is not set, there is no change to
1159 // the operation, just stop using the Xor.
1160 if (!XorCst->isNegative()) {
1161 ICI.setOperand(0, CompareVal);
1166 // Was the old condition true if the operand is positive?
1167 bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
1169 // If so, the new one isn't.
1170 isTrueIfPositive ^= true;
1172 if (isTrueIfPositive)
1173 return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
1176 return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
1180 if (LHSI->hasOneUse()) {
1181 // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
1182 if (!ICI.isEquality() && XorCst->getValue().isSignBit()) {
1183 const APInt &SignBit = XorCst->getValue();
1184 ICmpInst::Predicate Pred = ICI.isSigned()
1185 ? ICI.getUnsignedPredicate()
1186 : ICI.getSignedPredicate();
1187 return new ICmpInst(Pred, LHSI->getOperand(0),
1188 Builder->getInt(RHSV ^ SignBit));
1191 // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
1192 if (!ICI.isEquality() && XorCst->isMaxValue(true)) {
1193 const APInt &NotSignBit = XorCst->getValue();
1194 ICmpInst::Predicate Pred = ICI.isSigned()
1195 ? ICI.getUnsignedPredicate()
1196 : ICI.getSignedPredicate();
1197 Pred = ICI.getSwappedPredicate(Pred);
1198 return new ICmpInst(Pred, LHSI->getOperand(0),
1199 Builder->getInt(RHSV ^ NotSignBit));
1203 // (icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
1204 // iff -C is a power of 2
1205 if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
1206 XorCst->getValue() == ~RHSV && (RHSV + 1).isPowerOf2())
1207 return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), XorCst);
1209 // (icmp ult (xor X, C), -C) -> (icmp uge X, C)
1210 // iff -C is a power of 2
1211 if (ICI.getPredicate() == ICmpInst::ICMP_ULT &&
1212 XorCst->getValue() == -RHSV && RHSV.isPowerOf2())
1213 return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), XorCst);
1216 case Instruction::And: // (icmp pred (and X, AndCst), RHS)
1217 if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
1218 LHSI->getOperand(0)->hasOneUse()) {
1219 ConstantInt *AndCst = cast<ConstantInt>(LHSI->getOperand(1));
1221 // If the LHS is an AND of a truncating cast, we can widen the
1222 // and/compare to be the input width without changing the value
1223 // produced, eliminating a cast.
1224 if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
1225 // We can do this transformation if either the AND constant does not
1226 // have its sign bit set or if it is an equality comparison.
1227 // Extending a relational comparison when we're checking the sign
1228 // bit would not work.
1229 if (ICI.isEquality() ||
1230 (!AndCst->isNegative() && RHSV.isNonNegative())) {
1232 Builder->CreateAnd(Cast->getOperand(0),
1233 ConstantExpr::getZExt(AndCst, Cast->getSrcTy()));
1234 NewAnd->takeName(LHSI);
1235 return new ICmpInst(ICI.getPredicate(), NewAnd,
1236 ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
1240 // If the LHS is an AND of a zext, and we have an equality compare, we can
1241 // shrink the and/compare to the smaller type, eliminating the cast.
1242 if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
1243 IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
1244 // Make sure we don't compare the upper bits, SimplifyDemandedBits
1245 // should fold the icmp to true/false in that case.
1246 if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) {
1248 Builder->CreateAnd(Cast->getOperand(0),
1249 ConstantExpr::getTrunc(AndCst, Ty));
1250 NewAnd->takeName(LHSI);
1251 return new ICmpInst(ICI.getPredicate(), NewAnd,
1252 ConstantExpr::getTrunc(RHS, Ty));
1256 // If this is: (X >> C1) & C2 != C3 (where any shift and any compare
1257 // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
1258 // happens a LOT in code produced by the C front-end, for bitfield
1260 BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
1261 if (Shift && !Shift->isShift())
1265 ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : nullptr;
1267 // This seemingly simple opportunity to fold away a shift turns out to
1268 // be rather complicated. See PR17827
1269 // ( http://llvm.org/bugs/show_bug.cgi?id=17827 ) for details.
1271 bool CanFold = false;
1272 unsigned ShiftOpcode = Shift->getOpcode();
1273 if (ShiftOpcode == Instruction::AShr) {
1274 // There may be some constraints that make this possible,
1275 // but nothing simple has been discovered yet.
1277 } else if (ShiftOpcode == Instruction::Shl) {
1278 // For a left shift, we can fold if the comparison is not signed.
1279 // We can also fold a signed comparison if the mask value and
1280 // comparison value are not negative. These constraints may not be
1281 // obvious, but we can prove that they are correct using an SMT
1283 if (!ICI.isSigned() || (!AndCst->isNegative() && !RHS->isNegative()))
1285 } else if (ShiftOpcode == Instruction::LShr) {
1286 // For a logical right shift, we can fold if the comparison is not
1287 // signed. We can also fold a signed comparison if the shifted mask
1288 // value and the shifted comparison value are not negative.
1289 // These constraints may not be obvious, but we can prove that they
1290 // are correct using an SMT solver.
1291 if (!ICI.isSigned())
1294 ConstantInt *ShiftedAndCst =
1295 cast<ConstantInt>(ConstantExpr::getShl(AndCst, ShAmt));
1296 ConstantInt *ShiftedRHSCst =
1297 cast<ConstantInt>(ConstantExpr::getShl(RHS, ShAmt));
1299 if (!ShiftedAndCst->isNegative() && !ShiftedRHSCst->isNegative())
1306 if (ShiftOpcode == Instruction::Shl)
1307 NewCst = ConstantExpr::getLShr(RHS, ShAmt);
1309 NewCst = ConstantExpr::getShl(RHS, ShAmt);
1311 // Check to see if we are shifting out any of the bits being
1313 if (ConstantExpr::get(ShiftOpcode, NewCst, ShAmt) != RHS) {
1314 // If we shifted bits out, the fold is not going to work out.
1315 // As a special case, check to see if this means that the
1316 // result is always true or false now.
1317 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
1318 return ReplaceInstUsesWith(ICI, Builder->getFalse());
1319 if (ICI.getPredicate() == ICmpInst::ICMP_NE)
1320 return ReplaceInstUsesWith(ICI, Builder->getTrue());
1322 ICI.setOperand(1, NewCst);
1323 Constant *NewAndCst;
1324 if (ShiftOpcode == Instruction::Shl)
1325 NewAndCst = ConstantExpr::getLShr(AndCst, ShAmt);
1327 NewAndCst = ConstantExpr::getShl(AndCst, ShAmt);
1328 LHSI->setOperand(1, NewAndCst);
1329 LHSI->setOperand(0, Shift->getOperand(0));
1330 Worklist.Add(Shift); // Shift is dead.
1336 // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
1337 // preferable because it allows the C<<Y expression to be hoisted out
1338 // of a loop if Y is invariant and X is not.
1339 if (Shift && Shift->hasOneUse() && RHSV == 0 &&
1340 ICI.isEquality() && !Shift->isArithmeticShift() &&
1341 !isa<Constant>(Shift->getOperand(0))) {
1344 if (Shift->getOpcode() == Instruction::LShr) {
1345 NS = Builder->CreateShl(AndCst, Shift->getOperand(1));
1347 // Insert a logical shift.
1348 NS = Builder->CreateLShr(AndCst, Shift->getOperand(1));
1351 // Compute X & (C << Y).
1353 Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
1355 ICI.setOperand(0, NewAnd);
1359 // (icmp pred (and (or (lshr X, Y), X), 1), 0) -->
1360 // (icmp pred (and X, (or (shl 1, Y), 1), 0))
1362 // iff pred isn't signed
1364 Value *X, *Y, *LShr;
1365 if (!ICI.isSigned() && RHSV == 0) {
1366 if (match(LHSI->getOperand(1), m_One())) {
1367 Constant *One = cast<Constant>(LHSI->getOperand(1));
1368 Value *Or = LHSI->getOperand(0);
1369 if (match(Or, m_Or(m_Value(LShr), m_Value(X))) &&
1370 match(LShr, m_LShr(m_Specific(X), m_Value(Y)))) {
1371 unsigned UsesRemoved = 0;
1372 if (LHSI->hasOneUse())
1374 if (Or->hasOneUse())
1376 if (LShr->hasOneUse())
1378 Value *NewOr = nullptr;
1379 // Compute X & ((1 << Y) | 1)
1380 if (auto *C = dyn_cast<Constant>(Y)) {
1381 if (UsesRemoved >= 1)
1383 ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One);
1385 if (UsesRemoved >= 3)
1386 NewOr = Builder->CreateOr(Builder->CreateShl(One, Y,
1389 One, Or->getName());
1392 Value *NewAnd = Builder->CreateAnd(X, NewOr, LHSI->getName());
1393 ICI.setOperand(0, NewAnd);
1401 // Replace ((X & AndCst) > RHSV) with ((X & AndCst) != 0), if any
1402 // bit set in (X & AndCst) will produce a result greater than RHSV.
1403 if (ICI.getPredicate() == ICmpInst::ICMP_UGT) {
1404 unsigned NTZ = AndCst->getValue().countTrailingZeros();
1405 if ((NTZ < AndCst->getBitWidth()) &&
1406 APInt::getOneBitSet(AndCst->getBitWidth(), NTZ).ugt(RHSV))
1407 return new ICmpInst(ICmpInst::ICMP_NE, LHSI,
1408 Constant::getNullValue(RHS->getType()));
1412 // Try to optimize things like "A[i]&42 == 0" to index computations.
1413 if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
1414 if (GetElementPtrInst *GEP =
1415 dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
1416 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
1417 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
1418 !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
1419 ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
1420 if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
1425 // X & -C == -C -> X > u ~C
1426 // X & -C != -C -> X <= u ~C
1427 // iff C is a power of 2
1428 if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-RHSV).isPowerOf2())
1429 return new ICmpInst(
1430 ICI.getPredicate() == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_UGT
1431 : ICmpInst::ICMP_ULE,
1432 LHSI->getOperand(0), SubOne(RHS));
1435 case Instruction::Or: {
1436 if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
1439 if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
1440 // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
1441 // -> and (icmp eq P, null), (icmp eq Q, null).
1442 Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
1443 Constant::getNullValue(P->getType()));
1444 Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
1445 Constant::getNullValue(Q->getType()));
1447 if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
1448 Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
1450 Op = BinaryOperator::CreateOr(ICIP, ICIQ);
1456 case Instruction::Mul: { // (icmp pred (mul X, Val), CI)
1457 ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1460 // If this is a signed comparison to 0 and the mul is sign preserving,
1461 // use the mul LHS operand instead.
1462 ICmpInst::Predicate pred = ICI.getPredicate();
1463 if (isSignTest(pred, RHS) && !Val->isZero() &&
1464 cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
1465 return new ICmpInst(Val->isNegative() ?
1466 ICmpInst::getSwappedPredicate(pred) : pred,
1467 LHSI->getOperand(0),
1468 Constant::getNullValue(RHS->getType()));
1473 case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
1474 uint32_t TypeBits = RHSV.getBitWidth();
1475 ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1478 // (1 << X) pred P2 -> X pred Log2(P2)
1479 if (match(LHSI, m_Shl(m_One(), m_Value(X)))) {
1480 bool RHSVIsPowerOf2 = RHSV.isPowerOf2();
1481 ICmpInst::Predicate Pred = ICI.getPredicate();
1482 if (ICI.isUnsigned()) {
1483 if (!RHSVIsPowerOf2) {
1484 // (1 << X) < 30 -> X <= 4
1485 // (1 << X) <= 30 -> X <= 4
1486 // (1 << X) >= 30 -> X > 4
1487 // (1 << X) > 30 -> X > 4
1488 if (Pred == ICmpInst::ICMP_ULT)
1489 Pred = ICmpInst::ICMP_ULE;
1490 else if (Pred == ICmpInst::ICMP_UGE)
1491 Pred = ICmpInst::ICMP_UGT;
1493 unsigned RHSLog2 = RHSV.logBase2();
1495 // (1 << X) >= 2147483648 -> X >= 31 -> X == 31
1496 // (1 << X) < 2147483648 -> X < 31 -> X != 31
1497 if (RHSLog2 == TypeBits-1) {
1498 if (Pred == ICmpInst::ICMP_UGE)
1499 Pred = ICmpInst::ICMP_EQ;
1500 else if (Pred == ICmpInst::ICMP_ULT)
1501 Pred = ICmpInst::ICMP_NE;
1504 return new ICmpInst(Pred, X,
1505 ConstantInt::get(RHS->getType(), RHSLog2));
1506 } else if (ICI.isSigned()) {
1507 if (RHSV.isAllOnesValue()) {
1508 // (1 << X) <= -1 -> X == 31
1509 if (Pred == ICmpInst::ICMP_SLE)
1510 return new ICmpInst(ICmpInst::ICMP_EQ, X,
1511 ConstantInt::get(RHS->getType(), TypeBits-1));
1513 // (1 << X) > -1 -> X != 31
1514 if (Pred == ICmpInst::ICMP_SGT)
1515 return new ICmpInst(ICmpInst::ICMP_NE, X,
1516 ConstantInt::get(RHS->getType(), TypeBits-1));
1518 // (1 << X) < 0 -> X == 31
1519 // (1 << X) <= 0 -> X == 31
1520 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
1521 return new ICmpInst(ICmpInst::ICMP_EQ, X,
1522 ConstantInt::get(RHS->getType(), TypeBits-1));
1524 // (1 << X) >= 0 -> X != 31
1525 // (1 << X) > 0 -> X != 31
1526 if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
1527 return new ICmpInst(ICmpInst::ICMP_NE, X,
1528 ConstantInt::get(RHS->getType(), TypeBits-1));
1530 } else if (ICI.isEquality()) {
1532 return new ICmpInst(
1533 Pred, X, ConstantInt::get(RHS->getType(), RHSV.logBase2()));
1539 // Check that the shift amount is in range. If not, don't perform
1540 // undefined shifts. When the shift is visited it will be
1542 if (ShAmt->uge(TypeBits))
1545 if (ICI.isEquality()) {
1546 // If we are comparing against bits always shifted out, the
1547 // comparison cannot succeed.
1549 ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
1551 if (Comp != RHS) {// Comparing against a bit that we know is zero.
1552 bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1553 Constant *Cst = Builder->getInt1(IsICMP_NE);
1554 return ReplaceInstUsesWith(ICI, Cst);
1557 // If the shift is NUW, then it is just shifting out zeros, no need for an
1559 if (cast<BinaryOperator>(LHSI)->hasNoUnsignedWrap())
1560 return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1561 ConstantExpr::getLShr(RHS, ShAmt));
1563 // If the shift is NSW and we compare to 0, then it is just shifting out
1564 // sign bits, no need for an AND either.
1565 if (cast<BinaryOperator>(LHSI)->hasNoSignedWrap() && RHSV == 0)
1566 return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
1567 ConstantExpr::getLShr(RHS, ShAmt));
1569 if (LHSI->hasOneUse()) {
1570 // Otherwise strength reduce the shift into an and.
1571 uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
1572 Constant *Mask = Builder->getInt(APInt::getLowBitsSet(TypeBits,
1573 TypeBits - ShAmtVal));
1576 Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
1577 return new ICmpInst(ICI.getPredicate(), And,
1578 ConstantExpr::getLShr(RHS, ShAmt));
1582 // If this is a signed comparison to 0 and the shift is sign preserving,
1583 // use the shift LHS operand instead.
1584 ICmpInst::Predicate pred = ICI.getPredicate();
1585 if (isSignTest(pred, RHS) &&
1586 cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
1587 return new ICmpInst(pred,
1588 LHSI->getOperand(0),
1589 Constant::getNullValue(RHS->getType()));
1591 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
1592 bool TrueIfSigned = false;
1593 if (LHSI->hasOneUse() &&
1594 isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
1595 // (X << 31) <s 0 --> (X&1) != 0
1596 Constant *Mask = ConstantInt::get(LHSI->getOperand(0)->getType(),
1597 APInt::getOneBitSet(TypeBits,
1598 TypeBits-ShAmt->getZExtValue()-1));
1600 Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
1601 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
1602 And, Constant::getNullValue(And->getType()));
1605 // Transform (icmp pred iM (shl iM %v, N), CI)
1606 // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (CI>>N))
1607 // Transform the shl to a trunc if (trunc (CI>>N)) has no loss and M-N.
1608 // This enables to get rid of the shift in favor of a trunc which can be
1609 // free on the target. It has the additional benefit of comparing to a
1610 // smaller constant, which will be target friendly.
1611 unsigned Amt = ShAmt->getLimitedValue(TypeBits-1);
1612 if (LHSI->hasOneUse() &&
1613 Amt != 0 && RHSV.countTrailingZeros() >= Amt) {
1614 Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt);
1615 Constant *NCI = ConstantExpr::getTrunc(
1616 ConstantExpr::getAShr(RHS,
1617 ConstantInt::get(RHS->getType(), Amt)),
1619 return new ICmpInst(ICI.getPredicate(),
1620 Builder->CreateTrunc(LHSI->getOperand(0), NTy),
1627 case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
1628 case Instruction::AShr: {
1629 // Handle equality comparisons of shift-by-constant.
1630 BinaryOperator *BO = cast<BinaryOperator>(LHSI);
1631 if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
1632 if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt))
1636 // Handle exact shr's.
1637 if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) {
1638 if (RHSV.isMinValue())
1639 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS);
1644 case Instruction::SDiv:
1645 case Instruction::UDiv:
1646 // Fold: icmp pred ([us]div X, C1), C2 -> range test
1647 // Fold this div into the comparison, producing a range check.
1648 // Determine, based on the divide type, what the range is being
1649 // checked. If there is an overflow on the low or high side, remember
1650 // it, otherwise compute the range [low, hi) bounding the new value.
1651 // See: InsertRangeTest above for the kinds of replacements possible.
1652 if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
1653 if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
1658 case Instruction::Sub: {
1659 ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0));
1661 const APInt &LHSV = LHSC->getValue();
1663 // C1-X <u C2 -> (X|(C2-1)) == C1
1664 // iff C1 & (C2-1) == C2-1
1665 // C2 is a power of 2
1666 if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
1667 RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1))
1668 return new ICmpInst(ICmpInst::ICMP_EQ,
1669 Builder->CreateOr(LHSI->getOperand(1), RHSV - 1),
1672 // C1-X >u C2 -> (X|C2) != C1
1673 // iff C1 & C2 == C2
1674 // C2+1 is a power of 2
1675 if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
1676 (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV)
1677 return new ICmpInst(ICmpInst::ICMP_NE,
1678 Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC);
1682 case Instruction::Add:
1683 // Fold: icmp pred (add X, C1), C2
1684 if (!ICI.isEquality()) {
1685 ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
1687 const APInt &LHSV = LHSC->getValue();
1689 ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
1692 if (ICI.isSigned()) {
1693 if (CR.getLower().isSignBit()) {
1694 return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
1695 Builder->getInt(CR.getUpper()));
1696 } else if (CR.getUpper().isSignBit()) {
1697 return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
1698 Builder->getInt(CR.getLower()));
1701 if (CR.getLower().isMinValue()) {
1702 return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
1703 Builder->getInt(CR.getUpper()));
1704 } else if (CR.getUpper().isMinValue()) {
1705 return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
1706 Builder->getInt(CR.getLower()));
1710 // X-C1 <u C2 -> (X & -C2) == C1
1711 // iff C1 & (C2-1) == 0
1712 // C2 is a power of 2
1713 if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
1714 RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0)
1715 return new ICmpInst(ICmpInst::ICMP_EQ,
1716 Builder->CreateAnd(LHSI->getOperand(0), -RHSV),
1717 ConstantExpr::getNeg(LHSC));
1719 // X-C1 >u C2 -> (X & ~C2) != C1
1721 // C2+1 is a power of 2
1722 if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
1723 (RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0)
1724 return new ICmpInst(ICmpInst::ICMP_NE,
1725 Builder->CreateAnd(LHSI->getOperand(0), ~RHSV),
1726 ConstantExpr::getNeg(LHSC));
1731 // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
1732 if (ICI.isEquality()) {
1733 bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
1735 // If the first operand is (add|sub|and|or|xor|rem) with a constant, and
1736 // the second operand is a constant, simplify a bit.
1737 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
1738 switch (BO->getOpcode()) {
1739 case Instruction::SRem:
1740 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
1741 if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
1742 const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
1743 if (V.sgt(1) && V.isPowerOf2()) {
1745 Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
1747 return new ICmpInst(ICI.getPredicate(), NewRem,
1748 Constant::getNullValue(BO->getType()));
1752 case Instruction::Add:
1753 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
1754 if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1755 if (BO->hasOneUse())
1756 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1757 ConstantExpr::getSub(RHS, BOp1C));
1758 } else if (RHSV == 0) {
1759 // Replace ((add A, B) != 0) with (A != -B) if A or B is
1760 // efficiently invertible, or if the add has just this one use.
1761 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
1763 if (Value *NegVal = dyn_castNegVal(BOp1))
1764 return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
1765 if (Value *NegVal = dyn_castNegVal(BOp0))
1766 return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
1767 if (BO->hasOneUse()) {
1768 Value *Neg = Builder->CreateNeg(BOp1);
1770 return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
1774 case Instruction::Xor:
1775 // For the xor case, we can xor two constants together, eliminating
1776 // the explicit xor.
1777 if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
1778 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1779 ConstantExpr::getXor(RHS, BOC));
1780 } else if (RHSV == 0) {
1781 // Replace ((xor A, B) != 0) with (A != B)
1782 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1786 case Instruction::Sub:
1787 // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
1788 if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
1789 if (BO->hasOneUse())
1790 return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
1791 ConstantExpr::getSub(BOp0C, RHS));
1792 } else if (RHSV == 0) {
1793 // Replace ((sub A, B) != 0) with (A != B)
1794 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1798 case Instruction::Or:
1799 // If bits are being or'd in that are not present in the constant we
1800 // are comparing against, then the comparison could never succeed!
1801 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1802 Constant *NotCI = ConstantExpr::getNot(RHS);
1803 if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
1804 return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
1808 case Instruction::And:
1809 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1810 // If bits are being compared against that are and'd out, then the
1811 // comparison can never succeed!
1812 if ((RHSV & ~BOC->getValue()) != 0)
1813 return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
1815 // If we have ((X & C) == C), turn it into ((X & C) != 0).
1816 if (RHS == BOC && RHSV.isPowerOf2())
1817 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
1818 ICmpInst::ICMP_NE, LHSI,
1819 Constant::getNullValue(RHS->getType()));
1821 // Don't perform the following transforms if the AND has multiple uses
1822 if (!BO->hasOneUse())
1825 // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
1826 if (BOC->getValue().isSignBit()) {
1827 Value *X = BO->getOperand(0);
1828 Constant *Zero = Constant::getNullValue(X->getType());
1829 ICmpInst::Predicate pred = isICMP_NE ?
1830 ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
1831 return new ICmpInst(pred, X, Zero);
1834 // ((X & ~7) == 0) --> X < 8
1835 if (RHSV == 0 && isHighOnes(BOC)) {
1836 Value *X = BO->getOperand(0);
1837 Constant *NegX = ConstantExpr::getNeg(BOC);
1838 ICmpInst::Predicate pred = isICMP_NE ?
1839 ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
1840 return new ICmpInst(pred, X, NegX);
1844 case Instruction::Mul:
1845 if (RHSV == 0 && BO->hasNoSignedWrap()) {
1846 if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
1847 // The trivial case (mul X, 0) is handled by InstSimplify
1848 // General case : (mul X, C) != 0 iff X != 0
1849 // (mul X, C) == 0 iff X == 0
1851 return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
1852 Constant::getNullValue(RHS->getType()));
1858 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
1859 // Handle icmp {eq|ne} <intrinsic>, intcst.
1860 switch (II->getIntrinsicID()) {
1861 case Intrinsic::bswap:
1863 ICI.setOperand(0, II->getArgOperand(0));
1864 ICI.setOperand(1, Builder->getInt(RHSV.byteSwap()));
1866 case Intrinsic::ctlz:
1867 case Intrinsic::cttz:
1868 // ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
1869 if (RHSV == RHS->getType()->getBitWidth()) {
1871 ICI.setOperand(0, II->getArgOperand(0));
1872 ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
1876 case Intrinsic::ctpop:
1877 // popcount(A) == 0 -> A == 0 and likewise for !=
1878 if (RHS->isZero()) {
1880 ICI.setOperand(0, II->getArgOperand(0));
1881 ICI.setOperand(1, RHS);
1893 /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
1894 /// We only handle extending casts so far.
1896 Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
1897 const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
1898 Value *LHSCIOp = LHSCI->getOperand(0);
1899 Type *SrcTy = LHSCIOp->getType();
1900 Type *DestTy = LHSCI->getType();
1903 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
1904 // integer type is the same size as the pointer type.
1905 if (DL && LHSCI->getOpcode() == Instruction::PtrToInt &&
1906 DL->getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) {
1907 Value *RHSOp = nullptr;
1908 if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
1909 RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
1910 } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
1911 RHSOp = RHSC->getOperand(0);
1912 // If the pointer types don't match, insert a bitcast.
1913 if (LHSCIOp->getType() != RHSOp->getType())
1914 RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
1918 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
1921 // The code below only handles extension cast instructions, so far.
1923 if (LHSCI->getOpcode() != Instruction::ZExt &&
1924 LHSCI->getOpcode() != Instruction::SExt)
1927 bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
1928 bool isSignedCmp = ICI.isSigned();
1930 if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
1931 // Not an extension from the same type?
1932 RHSCIOp = CI->getOperand(0);
1933 if (RHSCIOp->getType() != LHSCIOp->getType())
1936 // If the signedness of the two casts doesn't agree (i.e. one is a sext
1937 // and the other is a zext), then we can't handle this.
1938 if (CI->getOpcode() != LHSCI->getOpcode())
1941 // Deal with equality cases early.
1942 if (ICI.isEquality())
1943 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
1945 // A signed comparison of sign extended values simplifies into a
1946 // signed comparison.
1947 if (isSignedCmp && isSignedExt)
1948 return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
1950 // The other three cases all fold into an unsigned comparison.
1951 return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
1954 // If we aren't dealing with a constant on the RHS, exit early
1955 ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
1959 // Compute the constant that would happen if we truncated to SrcTy then
1960 // reextended to DestTy.
1961 Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
1962 Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
1965 // If the re-extended constant didn't change...
1967 // Deal with equality cases early.
1968 if (ICI.isEquality())
1969 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
1971 // A signed comparison of sign extended values simplifies into a
1972 // signed comparison.
1973 if (isSignedExt && isSignedCmp)
1974 return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
1976 // The other three cases all fold into an unsigned comparison.
1977 return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
1980 // The re-extended constant changed so the constant cannot be represented
1981 // in the shorter type. Consequently, we cannot emit a simple comparison.
1982 // All the cases that fold to true or false will have already been handled
1983 // by SimplifyICmpInst, so only deal with the tricky case.
1985 if (isSignedCmp || !isSignedExt)
1988 // Evaluate the comparison for LT (we invert for GT below). LE and GE cases
1989 // should have been folded away previously and not enter in here.
1991 // We're performing an unsigned comp with a sign extended value.
1992 // This is true if the input is >= 0. [aka >s -1]
1993 Constant *NegOne = Constant::getAllOnesValue(SrcTy);
1994 Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
1996 // Finally, return the value computed.
1997 if (ICI.getPredicate() == ICmpInst::ICMP_ULT)
1998 return ReplaceInstUsesWith(ICI, Result);
2000 assert(ICI.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!");
2001 return BinaryOperator::CreateNot(Result);
2004 /// ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form:
2005 /// I = icmp ugt (add (add A, B), CI2), CI1
2006 /// If this is of the form:
2008 /// if (sum+128 >u 255)
2009 /// Then replace it with llvm.sadd.with.overflow.i8.
2011 static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
2012 ConstantInt *CI2, ConstantInt *CI1,
2014 // The transformation we're trying to do here is to transform this into an
2015 // llvm.sadd.with.overflow. To do this, we have to replace the original add
2016 // with a narrower add, and discard the add-with-constant that is part of the
2017 // range check (if we can't eliminate it, this isn't profitable).
2019 // In order to eliminate the add-with-constant, the compare can be its only
2021 Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
2022 if (!AddWithCst->hasOneUse()) return nullptr;
2024 // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
2025 if (!CI2->getValue().isPowerOf2()) return nullptr;
2026 unsigned NewWidth = CI2->getValue().countTrailingZeros();
2027 if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) return nullptr;
2029 // The width of the new add formed is 1 more than the bias.
2032 // Check to see that CI1 is an all-ones value with NewWidth bits.
2033 if (CI1->getBitWidth() == NewWidth ||
2034 CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
2037 // This is only really a signed overflow check if the inputs have been
2038 // sign-extended; check for that condition. For example, if CI2 is 2^31 and
2039 // the operands of the add are 64 bits wide, we need at least 33 sign bits.
2040 unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
2041 if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits ||
2042 IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits)
2045 // In order to replace the original add with a narrower
2046 // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
2047 // and truncates that discard the high bits of the add. Verify that this is
2049 Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
2050 for (User *U : OrigAdd->users()) {
2051 if (U == AddWithCst) continue;
2053 // Only accept truncates for now. We would really like a nice recursive
2054 // predicate like SimplifyDemandedBits, but which goes downwards the use-def
2055 // chain to see which bits of a value are actually demanded. If the
2056 // original add had another add which was then immediately truncated, we
2057 // could still do the transformation.
2058 TruncInst *TI = dyn_cast<TruncInst>(U);
2059 if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth)
2063 // If the pattern matches, truncate the inputs to the narrower type and
2064 // use the sadd_with_overflow intrinsic to efficiently compute both the
2065 // result and the overflow bit.
2066 Module *M = I.getParent()->getParent()->getParent();
2068 Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
2069 Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow,
2072 InstCombiner::BuilderTy *Builder = IC.Builder;
2074 // Put the new code above the original add, in case there are any uses of the
2075 // add between the add and the compare.
2076 Builder->SetInsertPoint(OrigAdd);
2078 Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc");
2079 Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc");
2080 CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB, "sadd");
2081 Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result");
2082 Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType());
2084 // The inner add was the result of the narrow add, zero extended to the
2085 // wider type. Replace it with the result computed by the intrinsic.
2086 IC.ReplaceInstUsesWith(*OrigAdd, ZExt);
2088 // The original icmp gets replaced with the overflow value.
2089 return ExtractValueInst::Create(Call, 1, "sadd.overflow");
2092 static Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV,
2094 // Don't bother doing this transformation for pointers, don't do it for
2096 if (!isa<IntegerType>(OrigAddV->getType())) return nullptr;
2098 // If the add is a constant expr, then we don't bother transforming it.
2099 Instruction *OrigAdd = dyn_cast<Instruction>(OrigAddV);
2100 if (!OrigAdd) return nullptr;
2102 Value *LHS = OrigAdd->getOperand(0), *RHS = OrigAdd->getOperand(1);
2104 // Put the new code above the original add, in case there are any uses of the
2105 // add between the add and the compare.
2106 InstCombiner::BuilderTy *Builder = IC.Builder;
2107 Builder->SetInsertPoint(OrigAdd);
2109 Module *M = I.getParent()->getParent()->getParent();
2110 Type *Ty = LHS->getType();
2111 Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
2112 CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd");
2113 Value *Add = Builder->CreateExtractValue(Call, 0);
2115 IC.ReplaceInstUsesWith(*OrigAdd, Add);
2117 // The original icmp gets replaced with the overflow value.
2118 return ExtractValueInst::Create(Call, 1, "uadd.overflow");
2121 /// \brief Recognize and process idiom involving test for multiplication
2124 /// The caller has matched a pattern of the form:
2125 /// I = cmp u (mul(zext A, zext B), V
2126 /// The function checks if this is a test for overflow and if so replaces
2127 /// multiplication with call to 'mul.with.overflow' intrinsic.
2129 /// \param I Compare instruction.
2130 /// \param MulVal Result of 'mult' instruction. It is one of the arguments of
2131 /// the compare instruction. Must be of integer type.
2132 /// \param OtherVal The other argument of compare instruction.
2133 /// \returns Instruction which must replace the compare instruction, NULL if no
2134 /// replacement required.
2135 static Instruction *ProcessUMulZExtIdiom(ICmpInst &I, Value *MulVal,
2136 Value *OtherVal, InstCombiner &IC) {
2137 // Don't bother doing this transformation for pointers, don't do it for
2139 if (!isa<IntegerType>(MulVal->getType()))
2142 assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal);
2143 assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal);
2144 Instruction *MulInstr = cast<Instruction>(MulVal);
2145 assert(MulInstr->getOpcode() == Instruction::Mul);
2147 Instruction *LHS = cast<Instruction>(MulInstr->getOperand(0)),
2148 *RHS = cast<Instruction>(MulInstr->getOperand(1));
2149 assert(LHS->getOpcode() == Instruction::ZExt);
2150 assert(RHS->getOpcode() == Instruction::ZExt);
2151 Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
2153 // Calculate type and width of the result produced by mul.with.overflow.
2154 Type *TyA = A->getType(), *TyB = B->getType();
2155 unsigned WidthA = TyA->getPrimitiveSizeInBits(),
2156 WidthB = TyB->getPrimitiveSizeInBits();
2159 if (WidthB > WidthA) {
2167 // In order to replace the original mul with a narrower mul.with.overflow,
2168 // all uses must ignore upper bits of the product. The number of used low
2169 // bits must be not greater than the width of mul.with.overflow.
2170 if (MulVal->hasNUsesOrMore(2))
2171 for (User *U : MulVal->users()) {
2174 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
2175 // Check if truncation ignores bits above MulWidth.
2176 unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits();
2177 if (TruncWidth > MulWidth)
2179 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
2180 // Check if AND ignores bits above MulWidth.
2181 if (BO->getOpcode() != Instruction::And)
2183 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
2184 const APInt &CVal = CI->getValue();
2185 if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth)
2189 // Other uses prohibit this transformation.
2194 // Recognize patterns
2195 switch (I.getPredicate()) {
2196 case ICmpInst::ICMP_EQ:
2197 case ICmpInst::ICMP_NE:
2198 // Recognize pattern:
2199 // mulval = mul(zext A, zext B)
2200 // cmp eq/neq mulval, zext trunc mulval
2201 if (ZExtInst *Zext = dyn_cast<ZExtInst>(OtherVal))
2202 if (Zext->hasOneUse()) {
2203 Value *ZextArg = Zext->getOperand(0);
2204 if (TruncInst *Trunc = dyn_cast<TruncInst>(ZextArg))
2205 if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth)
2209 // Recognize pattern:
2210 // mulval = mul(zext A, zext B)
2211 // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits.
2214 if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) {
2215 if (ValToMask != MulVal)
2217 const APInt &CVal = CI->getValue() + 1;
2218 if (CVal.isPowerOf2()) {
2219 unsigned MaskWidth = CVal.logBase2();
2220 if (MaskWidth == MulWidth)
2221 break; // Recognized
2226 case ICmpInst::ICMP_UGT:
2227 // Recognize pattern:
2228 // mulval = mul(zext A, zext B)
2229 // cmp ugt mulval, max
2230 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2231 APInt MaxVal = APInt::getMaxValue(MulWidth);
2232 MaxVal = MaxVal.zext(CI->getBitWidth());
2233 if (MaxVal.eq(CI->getValue()))
2234 break; // Recognized
2238 case ICmpInst::ICMP_UGE:
2239 // Recognize pattern:
2240 // mulval = mul(zext A, zext B)
2241 // cmp uge mulval, max+1
2242 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2243 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
2244 if (MaxVal.eq(CI->getValue()))
2245 break; // Recognized
2249 case ICmpInst::ICMP_ULE:
2250 // Recognize pattern:
2251 // mulval = mul(zext A, zext B)
2252 // cmp ule mulval, max
2253 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2254 APInt MaxVal = APInt::getMaxValue(MulWidth);
2255 MaxVal = MaxVal.zext(CI->getBitWidth());
2256 if (MaxVal.eq(CI->getValue()))
2257 break; // Recognized
2261 case ICmpInst::ICMP_ULT:
2262 // Recognize pattern:
2263 // mulval = mul(zext A, zext B)
2264 // cmp ule mulval, max + 1
2265 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
2266 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
2267 if (MaxVal.eq(CI->getValue()))
2268 break; // Recognized
2276 InstCombiner::BuilderTy *Builder = IC.Builder;
2277 Builder->SetInsertPoint(MulInstr);
2278 Module *M = I.getParent()->getParent()->getParent();
2280 // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
2281 Value *MulA = A, *MulB = B;
2282 if (WidthA < MulWidth)
2283 MulA = Builder->CreateZExt(A, MulType);
2284 if (WidthB < MulWidth)
2285 MulB = Builder->CreateZExt(B, MulType);
2287 Intrinsic::getDeclaration(M, Intrinsic::umul_with_overflow, MulType);
2288 CallInst *Call = Builder->CreateCall2(F, MulA, MulB, "umul");
2289 IC.Worklist.Add(MulInstr);
2291 // If there are uses of mul result other than the comparison, we know that
2292 // they are truncation or binary AND. Change them to use result of
2293 // mul.with.overflow and adjust properly mask/size.
2294 if (MulVal->hasNUsesOrMore(2)) {
2295 Value *Mul = Builder->CreateExtractValue(Call, 0, "umul.value");
2296 for (User *U : MulVal->users()) {
2297 if (U == &I || U == OtherVal)
2299 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
2300 if (TI->getType()->getPrimitiveSizeInBits() == MulWidth)
2301 IC.ReplaceInstUsesWith(*TI, Mul);
2303 TI->setOperand(0, Mul);
2304 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
2305 assert(BO->getOpcode() == Instruction::And);
2306 // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
2307 ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
2308 APInt ShortMask = CI->getValue().trunc(MulWidth);
2309 Value *ShortAnd = Builder->CreateAnd(Mul, ShortMask);
2311 cast<Instruction>(Builder->CreateZExt(ShortAnd, BO->getType()));
2312 IC.Worklist.Add(Zext);
2313 IC.ReplaceInstUsesWith(*BO, Zext);
2315 llvm_unreachable("Unexpected Binary operation");
2317 IC.Worklist.Add(cast<Instruction>(U));
2320 if (isa<Instruction>(OtherVal))
2321 IC.Worklist.Add(cast<Instruction>(OtherVal));
2323 // The original icmp gets replaced with the overflow value, maybe inverted
2324 // depending on predicate.
2325 bool Inverse = false;
2326 switch (I.getPredicate()) {
2327 case ICmpInst::ICMP_NE:
2329 case ICmpInst::ICMP_EQ:
2332 case ICmpInst::ICMP_UGT:
2333 case ICmpInst::ICMP_UGE:
2334 if (I.getOperand(0) == MulVal)
2338 case ICmpInst::ICMP_ULT:
2339 case ICmpInst::ICMP_ULE:
2340 if (I.getOperand(1) == MulVal)
2345 llvm_unreachable("Unexpected predicate");
2348 Value *Res = Builder->CreateExtractValue(Call, 1);
2349 return BinaryOperator::CreateNot(Res);
2352 return ExtractValueInst::Create(Call, 1);
2355 // DemandedBitsLHSMask - When performing a comparison against a constant,
2356 // it is possible that not all the bits in the LHS are demanded. This helper
2357 // method computes the mask that IS demanded.
2358 static APInt DemandedBitsLHSMask(ICmpInst &I,
2359 unsigned BitWidth, bool isSignCheck) {
2361 return APInt::getSignBit(BitWidth);
2363 ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1));
2364 if (!CI) return APInt::getAllOnesValue(BitWidth);
2365 const APInt &RHS = CI->getValue();
2367 switch (I.getPredicate()) {
2368 // For a UGT comparison, we don't care about any bits that
2369 // correspond to the trailing ones of the comparand. The value of these
2370 // bits doesn't impact the outcome of the comparison, because any value
2371 // greater than the RHS must differ in a bit higher than these due to carry.
2372 case ICmpInst::ICMP_UGT: {
2373 unsigned trailingOnes = RHS.countTrailingOnes();
2374 APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes);
2378 // Similarly, for a ULT comparison, we don't care about the trailing zeros.
2379 // Any value less than the RHS must differ in a higher bit because of carries.
2380 case ICmpInst::ICMP_ULT: {
2381 unsigned trailingZeros = RHS.countTrailingZeros();
2382 APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros);
2387 return APInt::getAllOnesValue(BitWidth);
2392 /// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst
2393 /// should be swapped.
2394 /// The decision is based on how many times these two operands are reused
2395 /// as subtract operands and their positions in those instructions.
2396 /// The rational is that several architectures use the same instruction for
2397 /// both subtract and cmp, thus it is better if the order of those operands
2399 /// \return true if Op0 and Op1 should be swapped.
2400 static bool swapMayExposeCSEOpportunities(const Value * Op0,
2401 const Value * Op1) {
2402 // Filter out pointer value as those cannot appears directly in subtract.
2403 // FIXME: we may want to go through inttoptrs or bitcasts.
2404 if (Op0->getType()->isPointerTy())
2406 // Count every uses of both Op0 and Op1 in a subtract.
2407 // Each time Op0 is the first operand, count -1: swapping is bad, the
2408 // subtract has already the same layout as the compare.
2409 // Each time Op0 is the second operand, count +1: swapping is good, the
2410 // subtract has a different layout as the compare.
2411 // At the end, if the benefit is greater than 0, Op0 should come second to
2412 // expose more CSE opportunities.
2413 int GlobalSwapBenefits = 0;
2414 for (const User *U : Op0->users()) {
2415 const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(U);
2416 if (!BinOp || BinOp->getOpcode() != Instruction::Sub)
2418 // If Op0 is the first argument, this is not beneficial to swap the
2420 int LocalSwapBenefits = -1;
2421 unsigned Op1Idx = 1;
2422 if (BinOp->getOperand(Op1Idx) == Op0) {
2424 LocalSwapBenefits = 1;
2426 if (BinOp->getOperand(Op1Idx) != Op1)
2428 GlobalSwapBenefits += LocalSwapBenefits;
2430 return GlobalSwapBenefits > 0;
2433 Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
2434 bool Changed = false;
2435 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2436 unsigned Op0Cplxity = getComplexity(Op0);
2437 unsigned Op1Cplxity = getComplexity(Op1);
2439 /// Orders the operands of the compare so that they are listed from most
2440 /// complex to least complex. This puts constants before unary operators,
2441 /// before binary operators.
2442 if (Op0Cplxity < Op1Cplxity ||
2443 (Op0Cplxity == Op1Cplxity &&
2444 swapMayExposeCSEOpportunities(Op0, Op1))) {
2446 std::swap(Op0, Op1);
2450 if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AT))
2451 return ReplaceInstUsesWith(I, V);
2453 // comparing -val or val with non-zero is the same as just comparing val
2454 // ie, abs(val) != 0 -> val != 0
2455 if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero()))
2457 Value *Cond, *SelectTrue, *SelectFalse;
2458 if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
2459 m_Value(SelectFalse)))) {
2460 if (Value *V = dyn_castNegVal(SelectTrue)) {
2461 if (V == SelectFalse)
2462 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
2464 else if (Value *V = dyn_castNegVal(SelectFalse)) {
2465 if (V == SelectTrue)
2466 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
2471 Type *Ty = Op0->getType();
2473 // icmp's with boolean values can always be turned into bitwise operations
2474 if (Ty->isIntegerTy(1)) {
2475 switch (I.getPredicate()) {
2476 default: llvm_unreachable("Invalid icmp instruction!");
2477 case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
2478 Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
2479 return BinaryOperator::CreateNot(Xor);
2481 case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
2482 return BinaryOperator::CreateXor(Op0, Op1);
2484 case ICmpInst::ICMP_UGT:
2485 std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
2487 case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
2488 Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
2489 return BinaryOperator::CreateAnd(Not, Op1);
2491 case ICmpInst::ICMP_SGT:
2492 std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
2494 case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
2495 Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
2496 return BinaryOperator::CreateAnd(Not, Op0);
2498 case ICmpInst::ICMP_UGE:
2499 std::swap(Op0, Op1); // Change icmp uge -> icmp ule
2501 case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
2502 Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
2503 return BinaryOperator::CreateOr(Not, Op1);
2505 case ICmpInst::ICMP_SGE:
2506 std::swap(Op0, Op1); // Change icmp sge -> icmp sle
2508 case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
2509 Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
2510 return BinaryOperator::CreateOr(Not, Op0);
2515 unsigned BitWidth = 0;
2516 if (Ty->isIntOrIntVectorTy())
2517 BitWidth = Ty->getScalarSizeInBits();
2518 else if (DL) // Pointers require DL info to get their size.
2519 BitWidth = DL->getTypeSizeInBits(Ty->getScalarType());
2521 bool isSignBit = false;
2523 // See if we are doing a comparison with a constant.
2524 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2525 Value *A = nullptr, *B = nullptr;
2527 // Match the following pattern, which is a common idiom when writing
2528 // overflow-safe integer arithmetic function. The source performs an
2529 // addition in wider type, and explicitly checks for overflow using
2530 // comparisons against INT_MIN and INT_MAX. Simplify this by using the
2531 // sadd_with_overflow intrinsic.
2533 // TODO: This could probably be generalized to handle other overflow-safe
2534 // operations if we worked out the formulas to compute the appropriate
2538 // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
2540 ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI
2541 if (I.getPredicate() == ICmpInst::ICMP_UGT &&
2542 match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
2543 if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this))
2547 // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
2548 if (I.isEquality() && CI->isZero() &&
2549 match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
2550 // (icmp cond A B) if cond is equality
2551 return new ICmpInst(I.getPredicate(), A, B);
2554 // If we have an icmp le or icmp ge instruction, turn it into the
2555 // appropriate icmp lt or icmp gt instruction. This allows us to rely on
2556 // them being folded in the code below. The SimplifyICmpInst code has
2557 // already handled the edge cases for us, so we just assert on them.
2558 switch (I.getPredicate()) {
2560 case ICmpInst::ICMP_ULE:
2561 assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
2562 return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
2563 Builder->getInt(CI->getValue()+1));
2564 case ICmpInst::ICMP_SLE:
2565 assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
2566 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
2567 Builder->getInt(CI->getValue()+1));
2568 case ICmpInst::ICMP_UGE:
2569 assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
2570 return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
2571 Builder->getInt(CI->getValue()-1));
2572 case ICmpInst::ICMP_SGE:
2573 assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
2574 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
2575 Builder->getInt(CI->getValue()-1));
2578 // (icmp eq/ne (ashr/lshr const2, A), const1)
2579 if (I.isEquality()) {
2581 if (match(Op0, m_AShr(m_ConstantInt(CI2), m_Value(A))) ||
2582 match(Op0, m_LShr(m_ConstantInt(CI2), m_Value(A)))) {
2583 return FoldICmpCstShrCst(I, Op0, A, CI, CI2);
2587 // If this comparison is a normal comparison, it demands all
2588 // bits, if it is a sign bit comparison, it only demands the sign bit.
2590 isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
2593 // See if we can fold the comparison based on range information we can get
2594 // by checking whether bits are known to be zero or one in the input.
2595 if (BitWidth != 0) {
2596 APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
2597 APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
2599 if (SimplifyDemandedBits(I.getOperandUse(0),
2600 DemandedBitsLHSMask(I, BitWidth, isSignBit),
2601 Op0KnownZero, Op0KnownOne, 0))
2603 if (SimplifyDemandedBits(I.getOperandUse(1),
2604 APInt::getAllOnesValue(BitWidth),
2605 Op1KnownZero, Op1KnownOne, 0))
2608 // Given the known and unknown bits, compute a range that the LHS could be
2609 // in. Compute the Min, Max and RHS values based on the known bits. For the
2610 // EQ and NE we use unsigned values.
2611 APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
2612 APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
2614 ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
2616 ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
2619 ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
2621 ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
2625 // If Min and Max are known to be the same, then SimplifyDemandedBits
2626 // figured out that the LHS is a constant. Just constant fold this now so
2627 // that code below can assume that Min != Max.
2628 if (!isa<Constant>(Op0) && Op0Min == Op0Max)
2629 return new ICmpInst(I.getPredicate(),
2630 ConstantInt::get(Op0->getType(), Op0Min), Op1);
2631 if (!isa<Constant>(Op1) && Op1Min == Op1Max)
2632 return new ICmpInst(I.getPredicate(), Op0,
2633 ConstantInt::get(Op1->getType(), Op1Min));
2635 // Based on the range information we know about the LHS, see if we can
2636 // simplify this comparison. For example, (x&4) < 8 is always true.
2637 switch (I.getPredicate()) {
2638 default: llvm_unreachable("Unknown icmp opcode!");
2639 case ICmpInst::ICMP_EQ: {
2640 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
2641 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2643 // If all bits are known zero except for one, then we know at most one
2644 // bit is set. If the comparison is against zero, then this is a check
2645 // to see if *that* bit is set.
2646 APInt Op0KnownZeroInverted = ~Op0KnownZero;
2647 if (~Op1KnownZero == 0) {
2648 // If the LHS is an AND with the same constant, look through it.
2649 Value *LHS = nullptr;
2650 ConstantInt *LHSC = nullptr;
2651 if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
2652 LHSC->getValue() != Op0KnownZeroInverted)
2655 // If the LHS is 1 << x, and we know the result is a power of 2 like 8,
2656 // then turn "((1 << x)&8) == 0" into "x != 3".
2657 // or turn "((1 << x)&7) == 0" into "x > 2".
2659 if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
2660 APInt ValToCheck = Op0KnownZeroInverted;
2661 if (ValToCheck.isPowerOf2()) {
2662 unsigned CmpVal = ValToCheck.countTrailingZeros();
2663 return new ICmpInst(ICmpInst::ICMP_NE, X,
2664 ConstantInt::get(X->getType(), CmpVal));
2665 } else if ((++ValToCheck).isPowerOf2()) {
2666 unsigned CmpVal = ValToCheck.countTrailingZeros() - 1;
2667 return new ICmpInst(ICmpInst::ICMP_UGT, X,
2668 ConstantInt::get(X->getType(), CmpVal));
2672 // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
2673 // then turn "((8 >>u x)&1) == 0" into "x != 3".
2675 if (Op0KnownZeroInverted == 1 &&
2676 match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
2677 return new ICmpInst(ICmpInst::ICMP_NE, X,
2678 ConstantInt::get(X->getType(),
2679 CI->countTrailingZeros()));
2684 case ICmpInst::ICMP_NE: {
2685 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
2686 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2688 // If all bits are known zero except for one, then we know at most one
2689 // bit is set. If the comparison is against zero, then this is a check
2690 // to see if *that* bit is set.
2691 APInt Op0KnownZeroInverted = ~Op0KnownZero;
2692 if (~Op1KnownZero == 0) {
2693 // If the LHS is an AND with the same constant, look through it.
2694 Value *LHS = nullptr;
2695 ConstantInt *LHSC = nullptr;
2696 if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
2697 LHSC->getValue() != Op0KnownZeroInverted)
2700 // If the LHS is 1 << x, and we know the result is a power of 2 like 8,
2701 // then turn "((1 << x)&8) != 0" into "x == 3".
2702 // or turn "((1 << x)&7) != 0" into "x < 3".
2704 if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
2705 APInt ValToCheck = Op0KnownZeroInverted;
2706 if (ValToCheck.isPowerOf2()) {
2707 unsigned CmpVal = ValToCheck.countTrailingZeros();
2708 return new ICmpInst(ICmpInst::ICMP_EQ, X,
2709 ConstantInt::get(X->getType(), CmpVal));
2710 } else if ((++ValToCheck).isPowerOf2()) {
2711 unsigned CmpVal = ValToCheck.countTrailingZeros();
2712 return new ICmpInst(ICmpInst::ICMP_ULT, X,
2713 ConstantInt::get(X->getType(), CmpVal));
2717 // If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
2718 // then turn "((8 >>u x)&1) != 0" into "x == 3".
2720 if (Op0KnownZeroInverted == 1 &&
2721 match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
2722 return new ICmpInst(ICmpInst::ICMP_EQ, X,
2723 ConstantInt::get(X->getType(),
2724 CI->countTrailingZeros()));
2729 case ICmpInst::ICMP_ULT:
2730 if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
2731 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2732 if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
2733 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2734 if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
2735 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2736 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2737 if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
2738 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2739 Builder->getInt(CI->getValue()-1));
2741 // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
2742 if (CI->isMinValue(true))
2743 return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
2744 Constant::getAllOnesValue(Op0->getType()));
2747 case ICmpInst::ICMP_UGT:
2748 if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
2749 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2750 if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
2751 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2753 if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
2754 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2755 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2756 if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
2757 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2758 Builder->getInt(CI->getValue()+1));
2760 // (x >u 2147483647) -> (x <s 0) -> true if sign bit set
2761 if (CI->isMaxValue(true))
2762 return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
2763 Constant::getNullValue(Op0->getType()));
2766 case ICmpInst::ICMP_SLT:
2767 if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
2768 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2769 if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
2770 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2771 if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
2772 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2773 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2774 if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
2775 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2776 Builder->getInt(CI->getValue()-1));
2779 case ICmpInst::ICMP_SGT:
2780 if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
2781 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2782 if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
2783 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2785 if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
2786 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
2787 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2788 if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
2789 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
2790 Builder->getInt(CI->getValue()+1));
2793 case ICmpInst::ICMP_SGE:
2794 assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
2795 if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
2796 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2797 if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
2798 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2800 case ICmpInst::ICMP_SLE:
2801 assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
2802 if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
2803 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2804 if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
2805 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2807 case ICmpInst::ICMP_UGE:
2808 assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
2809 if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
2810 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2811 if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
2812 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2814 case ICmpInst::ICMP_ULE:
2815 assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
2816 if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
2817 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
2818 if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
2819 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
2823 // Turn a signed comparison into an unsigned one if both operands
2824 // are known to have the same sign.
2826 ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
2827 (Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
2828 return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
2831 // Test if the ICmpInst instruction is used exclusively by a select as
2832 // part of a minimum or maximum operation. If so, refrain from doing
2833 // any other folding. This helps out other analyses which understand
2834 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
2835 // and CodeGen. And in this case, at least one of the comparison
2836 // operands has at least one user besides the compare (the select),
2837 // which would often largely negate the benefit of folding anyway.
2839 if (SelectInst *SI = dyn_cast<SelectInst>(*I.user_begin()))
2840 if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
2841 (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
2844 // See if we are doing a comparison between a constant and an instruction that
2845 // can be folded into the comparison.
2846 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
2847 // Since the RHS is a ConstantInt (CI), if the left hand side is an
2848 // instruction, see if that instruction also has constants so that the
2849 // instruction can be folded into the icmp
2850 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2851 if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
2855 // Handle icmp with constant (but not simple integer constant) RHS
2856 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
2857 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
2858 switch (LHSI->getOpcode()) {
2859 case Instruction::GetElementPtr:
2860 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
2861 if (RHSC->isNullValue() &&
2862 cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
2863 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
2864 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2866 case Instruction::PHI:
2867 // Only fold icmp into the PHI if the phi and icmp are in the same
2868 // block. If in the same block, we're encouraging jump threading. If
2869 // not, we are just pessimizing the code by making an i1 phi.
2870 if (LHSI->getParent() == I.getParent())
2871 if (Instruction *NV = FoldOpIntoPhi(I))
2874 case Instruction::Select: {
2875 // If either operand of the select is a constant, we can fold the
2876 // comparison into the select arms, which will cause one to be
2877 // constant folded and the select turned into a bitwise or.
2878 Value *Op1 = nullptr, *Op2 = nullptr;
2879 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
2880 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
2881 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
2882 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
2884 // We only want to perform this transformation if it will not lead to
2885 // additional code. This is true if either both sides of the select
2886 // fold to a constant (in which case the icmp is replaced with a select
2887 // which will usually simplify) or this is the only user of the
2888 // select (in which case we are trading a select+icmp for a simpler
2890 if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
2892 Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
2895 Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
2897 return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
2901 case Instruction::IntToPtr:
2902 // icmp pred inttoptr(X), null -> icmp pred X, 0
2903 if (RHSC->isNullValue() && DL &&
2904 DL->getIntPtrType(RHSC->getType()) ==
2905 LHSI->getOperand(0)->getType())
2906 return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
2907 Constant::getNullValue(LHSI->getOperand(0)->getType()));
2910 case Instruction::Load:
2911 // Try to optimize things like "A[i] > 4" to index computations.
2912 if (GetElementPtrInst *GEP =
2913 dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
2914 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
2915 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
2916 !cast<LoadInst>(LHSI)->isVolatile())
2917 if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
2924 // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
2925 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
2926 if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
2928 if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
2929 if (Instruction *NI = FoldGEPICmp(GEP, Op0,
2930 ICmpInst::getSwappedPredicate(I.getPredicate()), I))
2933 // Test to see if the operands of the icmp are casted versions of other
2934 // values. If the ptr->ptr cast can be stripped off both arguments, we do so
2936 if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
2937 if (Op0->getType()->isPointerTy() &&
2938 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
2939 // We keep moving the cast from the left operand over to the right
2940 // operand, where it can often be eliminated completely.
2941 Op0 = CI->getOperand(0);
2943 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
2944 // so eliminate it as well.
2945 if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
2946 Op1 = CI2->getOperand(0);
2948 // If Op1 is a constant, we can fold the cast into the constant.
2949 if (Op0->getType() != Op1->getType()) {
2950 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
2951 Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
2953 // Otherwise, cast the RHS right before the icmp
2954 Op1 = Builder->CreateBitCast(Op1, Op0->getType());
2957 return new ICmpInst(I.getPredicate(), Op0, Op1);
2961 if (isa<CastInst>(Op0)) {
2962 // Handle the special case of: icmp (cast bool to X), <cst>
2963 // This comes up when you have code like
2966 // For generality, we handle any zero-extension of any operand comparison
2967 // with a constant or another cast from the same type.
2968 if (isa<Constant>(Op1) || isa<CastInst>(Op1))
2969 if (Instruction *R = visitICmpInstWithCastAndCast(I))
2973 // Special logic for binary operators.
2974 BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
2975 BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
2977 CmpInst::Predicate Pred = I.getPredicate();
2978 bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
2979 if (BO0 && isa<OverflowingBinaryOperator>(BO0))
2980 NoOp0WrapProblem = ICmpInst::isEquality(Pred) ||
2981 (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
2982 (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
2983 if (BO1 && isa<OverflowingBinaryOperator>(BO1))
2984 NoOp1WrapProblem = ICmpInst::isEquality(Pred) ||
2985 (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
2986 (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
2988 // Analyze the case when either Op0 or Op1 is an add instruction.
2989 // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
2990 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
2991 if (BO0 && BO0->getOpcode() == Instruction::Add)
2992 A = BO0->getOperand(0), B = BO0->getOperand(1);
2993 if (BO1 && BO1->getOpcode() == Instruction::Add)
2994 C = BO1->getOperand(0), D = BO1->getOperand(1);
2996 // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
2997 if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
2998 return new ICmpInst(Pred, A == Op1 ? B : A,
2999 Constant::getNullValue(Op1->getType()));
3001 // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
3002 if ((C == Op0 || D == Op0) && NoOp1WrapProblem)
3003 return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
3006 // icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow.
3007 if (A && C && (A == C || A == D || B == C || B == D) &&
3008 NoOp0WrapProblem && NoOp1WrapProblem &&
3009 // Try not to increase register pressure.
3010 BO0->hasOneUse() && BO1->hasOneUse()) {
3011 // Determine Y and Z in the form icmp (X+Y), (X+Z).
3014 // C + B == C + D -> B == D
3017 } else if (A == D) {
3018 // D + B == C + D -> B == C
3021 } else if (B == C) {
3022 // A + C == C + D -> A == D
3027 // A + D == C + D -> A == C
3031 return new ICmpInst(Pred, Y, Z);
3034 // icmp slt (X + -1), Y -> icmp sle X, Y
3035 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
3036 match(B, m_AllOnes()))
3037 return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
3039 // icmp sge (X + -1), Y -> icmp sgt X, Y
3040 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
3041 match(B, m_AllOnes()))
3042 return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
3044 // icmp sle (X + 1), Y -> icmp slt X, Y
3045 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE &&
3047 return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
3049 // icmp sgt (X + 1), Y -> icmp sge X, Y
3050 if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT &&
3052 return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
3054 // if C1 has greater magnitude than C2:
3055 // icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
3056 // s.t. C3 = C1 - C2
3058 // if C2 has greater magnitude than C1:
3059 // icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
3060 // s.t. C3 = C2 - C1
3061 if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
3062 (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
3063 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
3064 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
3065 const APInt &AP1 = C1->getValue();
3066 const APInt &AP2 = C2->getValue();
3067 if (AP1.isNegative() == AP2.isNegative()) {
3068 APInt AP1Abs = C1->getValue().abs();
3069 APInt AP2Abs = C2->getValue().abs();
3070 if (AP1Abs.uge(AP2Abs)) {
3071 ConstantInt *C3 = Builder->getInt(AP1 - AP2);
3072 Value *NewAdd = Builder->CreateNSWAdd(A, C3);
3073 return new ICmpInst(Pred, NewAdd, C);
3075 ConstantInt *C3 = Builder->getInt(AP2 - AP1);
3076 Value *NewAdd = Builder->CreateNSWAdd(C, C3);
3077 return new ICmpInst(Pred, A, NewAdd);
3083 // Analyze the case when either Op0 or Op1 is a sub instruction.
3084 // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
3085 A = nullptr; B = nullptr; C = nullptr; D = nullptr;
3086 if (BO0 && BO0->getOpcode() == Instruction::Sub)
3087 A = BO0->getOperand(0), B = BO0->getOperand(1);
3088 if (BO1 && BO1->getOpcode() == Instruction::Sub)
3089 C = BO1->getOperand(0), D = BO1->getOperand(1);
3091 // icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow.
3092 if (A == Op1 && NoOp0WrapProblem)
3093 return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
3095 // icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow.
3096 if (C == Op0 && NoOp1WrapProblem)
3097 return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
3099 // icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow.
3100 if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem &&
3101 // Try not to increase register pressure.
3102 BO0->hasOneUse() && BO1->hasOneUse())
3103 return new ICmpInst(Pred, A, C);
3105 // icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow.
3106 if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
3107 // Try not to increase register pressure.
3108 BO0->hasOneUse() && BO1->hasOneUse())
3109 return new ICmpInst(Pred, D, B);
3111 // icmp (0-X) < cst --> x > -cst
3112 if (NoOp0WrapProblem && ICmpInst::isSigned(Pred)) {
3114 if (match(BO0, m_Neg(m_Value(X))))
3115 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
3116 if (!RHSC->isMinValue(/*isSigned=*/true))
3117 return new ICmpInst(I.getSwappedPredicate(), X,
3118 ConstantExpr::getNeg(RHSC));
3121 BinaryOperator *SRem = nullptr;
3122 // icmp (srem X, Y), Y
3123 if (BO0 && BO0->getOpcode() == Instruction::SRem &&
3124 Op1 == BO0->getOperand(1))
3126 // icmp Y, (srem X, Y)
3127 else if (BO1 && BO1->getOpcode() == Instruction::SRem &&
3128 Op0 == BO1->getOperand(1))
3131 // We don't check hasOneUse to avoid increasing register pressure because
3132 // the value we use is the same value this instruction was already using.
3133 switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
3135 case ICmpInst::ICMP_EQ:
3136 return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3137 case ICmpInst::ICMP_NE:
3138 return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
3139 case ICmpInst::ICMP_SGT:
3140 case ICmpInst::ICMP_SGE:
3141 return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
3142 Constant::getAllOnesValue(SRem->getType()));
3143 case ICmpInst::ICMP_SLT:
3144 case ICmpInst::ICMP_SLE:
3145 return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
3146 Constant::getNullValue(SRem->getType()));
3150 if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() &&
3151 BO0->hasOneUse() && BO1->hasOneUse() &&
3152 BO0->getOperand(1) == BO1->getOperand(1)) {
3153 switch (BO0->getOpcode()) {
3155 case Instruction::Add:
3156 case Instruction::Sub:
3157 case Instruction::Xor:
3158 if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
3159 return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3160 BO1->getOperand(0));
3161 // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
3162 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
3163 if (CI->getValue().isSignBit()) {
3164 ICmpInst::Predicate Pred = I.isSigned()
3165 ? I.getUnsignedPredicate()
3166 : I.getSignedPredicate();
3167 return new ICmpInst(Pred, BO0->getOperand(0),
3168 BO1->getOperand(0));
3171 if (CI->isMaxValue(true)) {
3172 ICmpInst::Predicate Pred = I.isSigned()
3173 ? I.getUnsignedPredicate()
3174 : I.getSignedPredicate();
3175 Pred = I.getSwappedPredicate(Pred);
3176 return new ICmpInst(Pred, BO0->getOperand(0),
3177 BO1->getOperand(0));
3181 case Instruction::Mul:
3182 if (!I.isEquality())
3185 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
3186 // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
3187 // Mask = -1 >> count-trailing-zeros(Cst).
3188 if (!CI->isZero() && !CI->isOne()) {
3189 const APInt &AP = CI->getValue();
3190 ConstantInt *Mask = ConstantInt::get(I.getContext(),
3191 APInt::getLowBitsSet(AP.getBitWidth(),
3193 AP.countTrailingZeros()));
3194 Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask);
3195 Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask);
3196 return new ICmpInst(I.getPredicate(), And1, And2);
3200 case Instruction::UDiv:
3201 case Instruction::LShr:
3205 case Instruction::SDiv:
3206 case Instruction::AShr:
3207 if (!BO0->isExact() || !BO1->isExact())
3209 return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3210 BO1->getOperand(0));
3211 case Instruction::Shl: {
3212 bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
3213 bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
3216 if (!NSW && I.isSigned())
3218 return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
3219 BO1->getOperand(0));
3226 // Transform (A & ~B) == 0 --> (A & B) != 0
3227 // and (A & ~B) != 0 --> (A & B) == 0
3228 // if A is a power of 2.
3229 if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
3230 match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(A, false,
3233 return new ICmpInst(I.getInversePredicate(),
3234 Builder->CreateAnd(A, B),
3237 // ~x < ~y --> y < x
3238 // ~x < cst --> ~cst < x
3239 if (match(Op0, m_Not(m_Value(A)))) {
3240 if (match(Op1, m_Not(m_Value(B))))
3241 return new ICmpInst(I.getPredicate(), B, A);
3242 if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
3243 return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A);
3246 // (a+b) <u a --> llvm.uadd.with.overflow.
3247 // (a+b) <u b --> llvm.uadd.with.overflow.
3248 if (I.getPredicate() == ICmpInst::ICMP_ULT &&
3249 match(Op0, m_Add(m_Value(A), m_Value(B))) &&
3250 (Op1 == A || Op1 == B))
3251 if (Instruction *R = ProcessUAddIdiom(I, Op0, *this))
3254 // a >u (a+b) --> llvm.uadd.with.overflow.
3255 // b >u (a+b) --> llvm.uadd.with.overflow.
3256 if (I.getPredicate() == ICmpInst::ICMP_UGT &&
3257 match(Op1, m_Add(m_Value(A), m_Value(B))) &&
3258 (Op0 == A || Op0 == B))
3259 if (Instruction *R = ProcessUAddIdiom(I, Op1, *this))
3262 // (zext a) * (zext b) --> llvm.umul.with.overflow.
3263 if (match(Op0, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
3264 if (Instruction *R = ProcessUMulZExtIdiom(I, Op0, Op1, *this))
3267 if (match(Op1, m_Mul(m_ZExt(m_Value(A)), m_ZExt(m_Value(B))))) {
3268 if (Instruction *R = ProcessUMulZExtIdiom(I, Op1, Op0, *this))
3273 if (I.isEquality()) {
3274 Value *A, *B, *C, *D;
3276 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
3277 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
3278 Value *OtherVal = A == Op1 ? B : A;
3279 return new ICmpInst(I.getPredicate(), OtherVal,
3280 Constant::getNullValue(A->getType()));
3283 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
3284 // A^c1 == C^c2 --> A == C^(c1^c2)
3285 ConstantInt *C1, *C2;
3286 if (match(B, m_ConstantInt(C1)) &&
3287 match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
3288 Constant *NC = Builder->getInt(C1->getValue() ^ C2->getValue());
3289 Value *Xor = Builder->CreateXor(C, NC);
3290 return new ICmpInst(I.getPredicate(), A, Xor);
3293 // A^B == A^D -> B == D
3294 if (A == C) return new ICmpInst(I.getPredicate(), B, D);
3295 if (A == D) return new ICmpInst(I.getPredicate(), B, C);
3296 if (B == C) return new ICmpInst(I.getPredicate(), A, D);
3297 if (B == D) return new ICmpInst(I.getPredicate(), A, C);
3301 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
3302 (A == Op0 || B == Op0)) {
3303 // A == (A^B) -> B == 0
3304 Value *OtherVal = A == Op0 ? B : A;
3305 return new ICmpInst(I.getPredicate(), OtherVal,
3306 Constant::getNullValue(A->getType()));
3309 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
3310 if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
3311 match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
3312 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
3315 X = B; Y = D; Z = A;
3316 } else if (A == D) {
3317 X = B; Y = C; Z = A;
3318 } else if (B == C) {
3319 X = A; Y = D; Z = B;
3320 } else if (B == D) {
3321 X = A; Y = C; Z = B;
3324 if (X) { // Build (X^Y) & Z
3325 Op1 = Builder->CreateXor(X, Y);
3326 Op1 = Builder->CreateAnd(Op1, Z);
3327 I.setOperand(0, Op1);
3328 I.setOperand(1, Constant::getNullValue(Op1->getType()));
3333 // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
3334 // and (B & (1<<X)-1) == (zext A) --> A == (trunc B)
3336 if ((Op0->hasOneUse() &&
3337 match(Op0, m_ZExt(m_Value(A))) &&
3338 match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
3339 (Op1->hasOneUse() &&
3340 match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
3341 match(Op1, m_ZExt(m_Value(A))))) {
3342 APInt Pow2 = Cst1->getValue() + 1;
3343 if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
3344 Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
3345 return new ICmpInst(I.getPredicate(), A,
3346 Builder->CreateTrunc(B, A->getType()));
3349 // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
3350 // For lshr and ashr pairs.
3351 if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3352 match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
3353 (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
3354 match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
3355 unsigned TypeBits = Cst1->getBitWidth();
3356 unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
3357 if (ShAmt < TypeBits && ShAmt != 0) {
3358 ICmpInst::Predicate Pred = I.getPredicate() == ICmpInst::ICMP_NE
3359 ? ICmpInst::ICMP_UGE
3360 : ICmpInst::ICMP_ULT;
3361 Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
3362 APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
3363 return new ICmpInst(Pred, Xor, Builder->getInt(CmpVal));
3367 // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
3368 // "icmp (and X, mask), cst"
3370 if (Op0->hasOneUse() &&
3371 match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A),
3372 m_ConstantInt(ShAmt))))) &&
3373 match(Op1, m_ConstantInt(Cst1)) &&
3374 // Only do this when A has multiple uses. This is most important to do
3375 // when it exposes other optimizations.
3377 unsigned ASize =cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
3379 if (ShAmt < ASize) {
3381 APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits());
3384 APInt CmpV = Cst1->getValue().zext(ASize);
3387 Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV));
3388 return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV));
3394 Value *X; ConstantInt *Cst;
3396 if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
3397 return FoldICmpAddOpCst(I, X, Cst, I.getPredicate());
3400 if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
3401 return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate());
3403 return Changed ? &I : nullptr;
3406 /// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
3408 Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
3411 if (!isa<ConstantFP>(RHSC)) return nullptr;
3412 const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
3414 // Get the width of the mantissa. We don't want to hack on conversions that
3415 // might lose information from the integer, e.g. "i64 -> float"
3416 int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
3417 if (MantissaWidth == -1) return nullptr; // Unknown.
3419 // Check to see that the input is converted from an integer type that is small
3420 // enough that preserves all bits. TODO: check here for "known" sign bits.
3421 // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
3422 unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
3424 // If this is a uitofp instruction, we need an extra bit to hold the sign.
3425 bool LHSUnsigned = isa<UIToFPInst>(LHSI);
3429 // If the conversion would lose info, don't hack on this.
3430 if ((int)InputSize > MantissaWidth)
3433 // Otherwise, we can potentially simplify the comparison. We know that it
3434 // will always come through as an integer value and we know the constant is
3435 // not a NAN (it would have been previously simplified).
3436 assert(!RHS.isNaN() && "NaN comparison not already folded!");
3438 ICmpInst::Predicate Pred;
3439 switch (I.getPredicate()) {
3440 default: llvm_unreachable("Unexpected predicate!");
3441 case FCmpInst::FCMP_UEQ:
3442 case FCmpInst::FCMP_OEQ:
3443 Pred = ICmpInst::ICMP_EQ;
3445 case FCmpInst::FCMP_UGT:
3446 case FCmpInst::FCMP_OGT:
3447 Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
3449 case FCmpInst::FCMP_UGE:
3450 case FCmpInst::FCMP_OGE:
3451 Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
3453 case FCmpInst::FCMP_ULT:
3454 case FCmpInst::FCMP_OLT:
3455 Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
3457 case FCmpInst::FCMP_ULE:
3458 case FCmpInst::FCMP_OLE:
3459 Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
3461 case FCmpInst::FCMP_UNE:
3462 case FCmpInst::FCMP_ONE:
3463 Pred = ICmpInst::ICMP_NE;
3465 case FCmpInst::FCMP_ORD:
3466 return ReplaceInstUsesWith(I, Builder->getTrue());
3467 case FCmpInst::FCMP_UNO:
3468 return ReplaceInstUsesWith(I, Builder->getFalse());
3471 IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
3473 // Now we know that the APFloat is a normal number, zero or inf.
3475 // See if the FP constant is too large for the integer. For example,
3476 // comparing an i8 to 300.0.
3477 unsigned IntWidth = IntTy->getScalarSizeInBits();
3480 // If the RHS value is > SignedMax, fold the comparison. This handles +INF
3481 // and large values.
3482 APFloat SMax(RHS.getSemantics());
3483 SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
3484 APFloat::rmNearestTiesToEven);
3485 if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
3486 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
3487 Pred == ICmpInst::ICMP_SLE)
3488 return ReplaceInstUsesWith(I, Builder->getTrue());
3489 return ReplaceInstUsesWith(I, Builder->getFalse());
3492 // If the RHS value is > UnsignedMax, fold the comparison. This handles
3493 // +INF and large values.
3494 APFloat UMax(RHS.getSemantics());
3495 UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
3496 APFloat::rmNearestTiesToEven);
3497 if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
3498 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
3499 Pred == ICmpInst::ICMP_ULE)
3500 return ReplaceInstUsesWith(I, Builder->getTrue());
3501 return ReplaceInstUsesWith(I, Builder->getFalse());
3506 // See if the RHS value is < SignedMin.
3507 APFloat SMin(RHS.getSemantics());
3508 SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
3509 APFloat::rmNearestTiesToEven);
3510 if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
3511 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
3512 Pred == ICmpInst::ICMP_SGE)
3513 return ReplaceInstUsesWith(I, Builder->getTrue());
3514 return ReplaceInstUsesWith(I, Builder->getFalse());
3517 // See if the RHS value is < UnsignedMin.
3518 APFloat SMin(RHS.getSemantics());
3519 SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true,
3520 APFloat::rmNearestTiesToEven);
3521 if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0
3522 if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT ||
3523 Pred == ICmpInst::ICMP_UGE)
3524 return ReplaceInstUsesWith(I, Builder->getTrue());
3525 return ReplaceInstUsesWith(I, Builder->getFalse());
3529 // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
3530 // [0, UMAX], but it may still be fractional. See if it is fractional by
3531 // casting the FP value to the integer value and back, checking for equality.
3532 // Don't do this for zero, because -0.0 is not fractional.
3533 Constant *RHSInt = LHSUnsigned
3534 ? ConstantExpr::getFPToUI(RHSC, IntTy)
3535 : ConstantExpr::getFPToSI(RHSC, IntTy);
3536 if (!RHS.isZero()) {
3537 bool Equal = LHSUnsigned
3538 ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
3539 : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
3541 // If we had a comparison against a fractional value, we have to adjust
3542 // the compare predicate and sometimes the value. RHSC is rounded towards
3543 // zero at this point.
3545 default: llvm_unreachable("Unexpected integer comparison!");
3546 case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
3547 return ReplaceInstUsesWith(I, Builder->getTrue());
3548 case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
3549 return ReplaceInstUsesWith(I, Builder->getFalse());
3550 case ICmpInst::ICMP_ULE:
3551 // (float)int <= 4.4 --> int <= 4
3552 // (float)int <= -4.4 --> false
3553 if (RHS.isNegative())
3554 return ReplaceInstUsesWith(I, Builder->getFalse());
3556 case ICmpInst::ICMP_SLE:
3557 // (float)int <= 4.4 --> int <= 4
3558 // (float)int <= -4.4 --> int < -4
3559 if (RHS.isNegative())
3560 Pred = ICmpInst::ICMP_SLT;
3562 case ICmpInst::ICMP_ULT:
3563 // (float)int < -4.4 --> false
3564 // (float)int < 4.4 --> int <= 4
3565 if (RHS.isNegative())
3566 return ReplaceInstUsesWith(I, Builder->getFalse());
3567 Pred = ICmpInst::ICMP_ULE;
3569 case ICmpInst::ICMP_SLT:
3570 // (float)int < -4.4 --> int < -4
3571 // (float)int < 4.4 --> int <= 4
3572 if (!RHS.isNegative())
3573 Pred = ICmpInst::ICMP_SLE;
3575 case ICmpInst::ICMP_UGT:
3576 // (float)int > 4.4 --> int > 4
3577 // (float)int > -4.4 --> true
3578 if (RHS.isNegative())
3579 return ReplaceInstUsesWith(I, Builder->getTrue());
3581 case ICmpInst::ICMP_SGT:
3582 // (float)int > 4.4 --> int > 4
3583 // (float)int > -4.4 --> int >= -4
3584 if (RHS.isNegative())
3585 Pred = ICmpInst::ICMP_SGE;
3587 case ICmpInst::ICMP_UGE:
3588 // (float)int >= -4.4 --> true
3589 // (float)int >= 4.4 --> int > 4
3590 if (RHS.isNegative())
3591 return ReplaceInstUsesWith(I, Builder->getTrue());
3592 Pred = ICmpInst::ICMP_UGT;
3594 case ICmpInst::ICMP_SGE:
3595 // (float)int >= -4.4 --> int >= -4
3596 // (float)int >= 4.4 --> int > 4
3597 if (!RHS.isNegative())
3598 Pred = ICmpInst::ICMP_SGT;
3604 // Lower this FP comparison into an appropriate integer version of the
3606 return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
3609 Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
3610 bool Changed = false;
3612 /// Orders the operands of the compare so that they are listed from most
3613 /// complex to least complex. This puts constants before unary operators,
3614 /// before binary operators.
3615 if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
3620 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3622 if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, DL, TLI, DT, AT))
3623 return ReplaceInstUsesWith(I, V);
3625 // Simplify 'fcmp pred X, X'
3627 switch (I.getPredicate()) {
3628 default: llvm_unreachable("Unknown predicate!");
3629 case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
3630 case FCmpInst::FCMP_ULT: // True if unordered or less than
3631 case FCmpInst::FCMP_UGT: // True if unordered or greater than
3632 case FCmpInst::FCMP_UNE: // True if unordered or not equal
3633 // Canonicalize these to be 'fcmp uno %X, 0.0'.
3634 I.setPredicate(FCmpInst::FCMP_UNO);
3635 I.setOperand(1, Constant::getNullValue(Op0->getType()));
3638 case FCmpInst::FCMP_ORD: // True if ordered (no nans)
3639 case FCmpInst::FCMP_OEQ: // True if ordered and equal
3640 case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
3641 case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
3642 // Canonicalize these to be 'fcmp ord %X, 0.0'.
3643 I.setPredicate(FCmpInst::FCMP_ORD);
3644 I.setOperand(1, Constant::getNullValue(Op0->getType()));
3649 // Handle fcmp with constant RHS
3650 if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
3651 if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
3652 switch (LHSI->getOpcode()) {
3653 case Instruction::FPExt: {
3654 // fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless
3655 FPExtInst *LHSExt = cast<FPExtInst>(LHSI);
3656 ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC);
3660 const fltSemantics *Sem;
3661 // FIXME: This shouldn't be here.
3662 if (LHSExt->getSrcTy()->isHalfTy())
3663 Sem = &APFloat::IEEEhalf;
3664 else if (LHSExt->getSrcTy()->isFloatTy())
3665 Sem = &APFloat::IEEEsingle;
3666 else if (LHSExt->getSrcTy()->isDoubleTy())
3667 Sem = &APFloat::IEEEdouble;
3668 else if (LHSExt->getSrcTy()->isFP128Ty())
3669 Sem = &APFloat::IEEEquad;
3670 else if (LHSExt->getSrcTy()->isX86_FP80Ty())
3671 Sem = &APFloat::x87DoubleExtended;
3672 else if (LHSExt->getSrcTy()->isPPC_FP128Ty())
3673 Sem = &APFloat::PPCDoubleDouble;
3678 APFloat F = RHSF->getValueAPF();
3679 F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy);
3681 // Avoid lossy conversions and denormals. Zero is a special case
3682 // that's OK to convert.
3686 ((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) !=
3687 APFloat::cmpLessThan) || Fabs.isZero()))
3689 return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
3690 ConstantFP::get(RHSC->getContext(), F));
3693 case Instruction::PHI:
3694 // Only fold fcmp into the PHI if the phi and fcmp are in the same
3695 // block. If in the same block, we're encouraging jump threading. If
3696 // not, we are just pessimizing the code by making an i1 phi.
3697 if (LHSI->getParent() == I.getParent())
3698 if (Instruction *NV = FoldOpIntoPhi(I))
3701 case Instruction::SIToFP:
3702 case Instruction::UIToFP:
3703 if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
3706 case Instruction::FSub: {
3707 // fcmp pred (fneg x), C -> fcmp swap(pred) x, -C
3709 if (match(LHSI, m_FNeg(m_Value(Op))))
3710 return new FCmpInst(I.getSwappedPredicate(), Op,
3711 ConstantExpr::getFNeg(RHSC));
3714 case Instruction::Load:
3715 if (GetElementPtrInst *GEP =
3716 dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
3717 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
3718 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
3719 !cast<LoadInst>(LHSI)->isVolatile())
3720 if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
3724 case Instruction::Call: {
3725 CallInst *CI = cast<CallInst>(LHSI);
3727 // Various optimization for fabs compared with zero.
3728 if (RHSC->isNullValue() && CI->getCalledFunction() &&
3729 TLI->getLibFunc(CI->getCalledFunction()->getName(), Func) &&
3731 if (Func == LibFunc::fabs || Func == LibFunc::fabsf ||
3732 Func == LibFunc::fabsl) {
3733 switch (I.getPredicate()) {
3735 // fabs(x) < 0 --> false
3736 case FCmpInst::FCMP_OLT:
3737 return ReplaceInstUsesWith(I, Builder->getFalse());
3738 // fabs(x) > 0 --> x != 0
3739 case FCmpInst::FCMP_OGT:
3740 return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0),
3742 // fabs(x) <= 0 --> x == 0
3743 case FCmpInst::FCMP_OLE:
3744 return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0),
3746 // fabs(x) >= 0 --> !isnan(x)
3747 case FCmpInst::FCMP_OGE:
3748 return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0),
3750 // fabs(x) == 0 --> x == 0
3751 // fabs(x) != 0 --> x != 0
3752 case FCmpInst::FCMP_OEQ:
3753 case FCmpInst::FCMP_UEQ:
3754 case FCmpInst::FCMP_ONE:
3755 case FCmpInst::FCMP_UNE:
3756 return new FCmpInst(I.getPredicate(), CI->getArgOperand(0),
3765 // fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y
3767 if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y))))
3768 return new FCmpInst(I.getSwappedPredicate(), X, Y);
3770 // fcmp (fpext x), (fpext y) -> fcmp x, y
3771 if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0))
3772 if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1))
3773 if (LHSExt->getSrcTy() == RHSExt->getSrcTy())
3774 return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
3775 RHSExt->getOperand(0));
3777 return Changed ? &I : nullptr;