Bug Summary

File:llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
Warning:line 3550, column 7
Called C++ object pointer is uninitialized

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name InstCombineCompares.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/build-llvm/lib/Transforms/InstCombine -resource-dir /usr/lib/llvm-13/lib/clang/13.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/build-llvm/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/build-llvm/include -I /build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../x86_64-linux-gnu/include -internal-isystem /usr/lib/llvm-13/lib/clang/13.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/build-llvm/lib/Transforms/InstCombine -fdebug-prefix-map=/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-04-05-202135-9119-1 -x c++ /build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

1//===- InstCombineCompares.cpp --------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the visitICmp and visitFCmp functions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "InstCombineInternal.h"
14#include "llvm/ADT/APSInt.h"
15#include "llvm/ADT/SetVector.h"
16#include "llvm/ADT/Statistic.h"
17#include "llvm/Analysis/ConstantFolding.h"
18#include "llvm/Analysis/InstructionSimplify.h"
19#include "llvm/Analysis/TargetLibraryInfo.h"
20#include "llvm/IR/ConstantRange.h"
21#include "llvm/IR/DataLayout.h"
22#include "llvm/IR/GetElementPtrTypeIterator.h"
23#include "llvm/IR/IntrinsicInst.h"
24#include "llvm/IR/PatternMatch.h"
25#include "llvm/Support/Debug.h"
26#include "llvm/Support/KnownBits.h"
27#include "llvm/Transforms/InstCombine/InstCombiner.h"
28
29using namespace llvm;
30using namespace PatternMatch;
31
32#define DEBUG_TYPE"instcombine" "instcombine"
33
34// How many times is a select replaced by one of its operands?
35STATISTIC(NumSel, "Number of select opts")static llvm::Statistic NumSel = {"instcombine", "NumSel", "Number of select opts"
}
;
36
37
38/// Compute Result = In1+In2, returning true if the result overflowed for this
39/// type.
40static bool addWithOverflow(APInt &Result, const APInt &In1,
41 const APInt &In2, bool IsSigned = false) {
42 bool Overflow;
43 if (IsSigned)
44 Result = In1.sadd_ov(In2, Overflow);
45 else
46 Result = In1.uadd_ov(In2, Overflow);
47
48 return Overflow;
49}
50
51/// Compute Result = In1-In2, returning true if the result overflowed for this
52/// type.
53static bool subWithOverflow(APInt &Result, const APInt &In1,
54 const APInt &In2, bool IsSigned = false) {
55 bool Overflow;
56 if (IsSigned)
57 Result = In1.ssub_ov(In2, Overflow);
58 else
59 Result = In1.usub_ov(In2, Overflow);
60
61 return Overflow;
62}
63
64/// Given an icmp instruction, return true if any use of this comparison is a
65/// branch on sign bit comparison.
66static bool hasBranchUse(ICmpInst &I) {
67 for (auto *U : I.users())
68 if (isa<BranchInst>(U))
69 return true;
70 return false;
71}
72
73/// Returns true if the exploded icmp can be expressed as a signed comparison
74/// to zero and updates the predicate accordingly.
75/// The signedness of the comparison is preserved.
76/// TODO: Refactor with decomposeBitTestICmp()?
77static bool isSignTest(ICmpInst::Predicate &Pred, const APInt &C) {
78 if (!ICmpInst::isSigned(Pred))
79 return false;
80
81 if (C.isNullValue())
82 return ICmpInst::isRelational(Pred);
83
84 if (C.isOneValue()) {
85 if (Pred == ICmpInst::ICMP_SLT) {
86 Pred = ICmpInst::ICMP_SLE;
87 return true;
88 }
89 } else if (C.isAllOnesValue()) {
90 if (Pred == ICmpInst::ICMP_SGT) {
91 Pred = ICmpInst::ICMP_SGE;
92 return true;
93 }
94 }
95
96 return false;
97}
98
99/// This is called when we see this pattern:
100/// cmp pred (load (gep GV, ...)), cmpcst
101/// where GV is a global variable with a constant initializer. Try to simplify
102/// this into some simple computation that does not need the load. For example
103/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
104///
105/// If AndCst is non-null, then the loaded value is masked with that constant
106/// before doing the comparison. This handles cases like "A[i]&4 == 0".
107Instruction *
108InstCombinerImpl::foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
109 GlobalVariable *GV, CmpInst &ICI,
110 ConstantInt *AndCst) {
111 Constant *Init = GV->getInitializer();
112 if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
113 return nullptr;
114
115 uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
116 // Don't blow up on huge arrays.
117 if (ArrayElementCount > MaxArraySizeForCombine)
118 return nullptr;
119
120 // There are many forms of this optimization we can handle, for now, just do
121 // the simple index into a single-dimensional array.
122 //
123 // Require: GEP GV, 0, i {{, constant indices}}
124 if (GEP->getNumOperands() < 3 ||
125 !isa<ConstantInt>(GEP->getOperand(1)) ||
126 !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
127 isa<Constant>(GEP->getOperand(2)))
128 return nullptr;
129
130 // Check that indices after the variable are constants and in-range for the
131 // type they index. Collect the indices. This is typically for arrays of
132 // structs.
133 SmallVector<unsigned, 4> LaterIndices;
134
135 Type *EltTy = Init->getType()->getArrayElementType();
136 for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
137 ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
138 if (!Idx) return nullptr; // Variable index.
139
140 uint64_t IdxVal = Idx->getZExtValue();
141 if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index.
142
143 if (StructType *STy = dyn_cast<StructType>(EltTy))
144 EltTy = STy->getElementType(IdxVal);
145 else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
146 if (IdxVal >= ATy->getNumElements()) return nullptr;
147 EltTy = ATy->getElementType();
148 } else {
149 return nullptr; // Unknown type.
150 }
151
152 LaterIndices.push_back(IdxVal);
153 }
154
155 enum { Overdefined = -3, Undefined = -2 };
156
157 // Variables for our state machines.
158
159 // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
160 // "i == 47 | i == 87", where 47 is the first index the condition is true for,
161 // and 87 is the second (and last) index. FirstTrueElement is -2 when
162 // undefined, otherwise set to the first true element. SecondTrueElement is
163 // -2 when undefined, -3 when overdefined and >= 0 when that index is true.
164 int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
165
166 // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
167 // form "i != 47 & i != 87". Same state transitions as for true elements.
168 int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
169
170 /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
171 /// define a state machine that triggers for ranges of values that the index
172 /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
173 /// This is -2 when undefined, -3 when overdefined, and otherwise the last
174 /// index in the range (inclusive). We use -2 for undefined here because we
175 /// use relative comparisons and don't want 0-1 to match -1.
176 int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
177
178 // MagicBitvector - This is a magic bitvector where we set a bit if the
179 // comparison is true for element 'i'. If there are 64 elements or less in
180 // the array, this will fully represent all the comparison results.
181 uint64_t MagicBitvector = 0;
182
183 // Scan the array and see if one of our patterns matches.
184 Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
185 for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
186 Constant *Elt = Init->getAggregateElement(i);
187 if (!Elt) return nullptr;
188
189 // If this is indexing an array of structures, get the structure element.
190 if (!LaterIndices.empty())
191 Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
192
193 // If the element is masked, handle it.
194 if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
195
196 // Find out if the comparison would be true or false for the i'th element.
197 Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
198 CompareRHS, DL, &TLI);
199 // If the result is undef for this element, ignore it.
200 if (isa<UndefValue>(C)) {
201 // Extend range state machines to cover this element in case there is an
202 // undef in the middle of the range.
203 if (TrueRangeEnd == (int)i-1)
204 TrueRangeEnd = i;
205 if (FalseRangeEnd == (int)i-1)
206 FalseRangeEnd = i;
207 continue;
208 }
209
210 // If we can't compute the result for any of the elements, we have to give
211 // up evaluating the entire conditional.
212 if (!isa<ConstantInt>(C)) return nullptr;
213
214 // Otherwise, we know if the comparison is true or false for this element,
215 // update our state machines.
216 bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
217
218 // State machine for single/double/range index comparison.
219 if (IsTrueForElt) {
220 // Update the TrueElement state machine.
221 if (FirstTrueElement == Undefined)
222 FirstTrueElement = TrueRangeEnd = i; // First true element.
223 else {
224 // Update double-compare state machine.
225 if (SecondTrueElement == Undefined)
226 SecondTrueElement = i;
227 else
228 SecondTrueElement = Overdefined;
229
230 // Update range state machine.
231 if (TrueRangeEnd == (int)i-1)
232 TrueRangeEnd = i;
233 else
234 TrueRangeEnd = Overdefined;
235 }
236 } else {
237 // Update the FalseElement state machine.
238 if (FirstFalseElement == Undefined)
239 FirstFalseElement = FalseRangeEnd = i; // First false element.
240 else {
241 // Update double-compare state machine.
242 if (SecondFalseElement == Undefined)
243 SecondFalseElement = i;
244 else
245 SecondFalseElement = Overdefined;
246
247 // Update range state machine.
248 if (FalseRangeEnd == (int)i-1)
249 FalseRangeEnd = i;
250 else
251 FalseRangeEnd = Overdefined;
252 }
253 }
254
255 // If this element is in range, update our magic bitvector.
256 if (i < 64 && IsTrueForElt)
257 MagicBitvector |= 1ULL << i;
258
259 // If all of our states become overdefined, bail out early. Since the
260 // predicate is expensive, only check it every 8 elements. This is only
261 // really useful for really huge arrays.
262 if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
263 SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
264 FalseRangeEnd == Overdefined)
265 return nullptr;
266 }
267
268 // Now that we've scanned the entire array, emit our new comparison(s). We
269 // order the state machines in complexity of the generated code.
270 Value *Idx = GEP->getOperand(2);
271
272 // If the index is larger than the pointer size of the target, truncate the
273 // index down like the GEP would do implicitly. We don't have to do this for
274 // an inbounds GEP because the index can't be out of range.
275 if (!GEP->isInBounds()) {
276 Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
277 unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
278 if (Idx->getType()->getPrimitiveSizeInBits().getFixedSize() > PtrSize)
279 Idx = Builder.CreateTrunc(Idx, IntPtrTy);
280 }
281
282 // If the comparison is only true for one or two elements, emit direct
283 // comparisons.
284 if (SecondTrueElement != Overdefined) {
285 // None true -> false.
286 if (FirstTrueElement == Undefined)
287 return replaceInstUsesWith(ICI, Builder.getFalse());
288
289 Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
290
291 // True for one element -> 'i == 47'.
292 if (SecondTrueElement == Undefined)
293 return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
294
295 // True for two elements -> 'i == 47 | i == 72'.
296 Value *C1 = Builder.CreateICmpEQ(Idx, FirstTrueIdx);
297 Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
298 Value *C2 = Builder.CreateICmpEQ(Idx, SecondTrueIdx);
299 return BinaryOperator::CreateOr(C1, C2);
300 }
301
302 // If the comparison is only false for one or two elements, emit direct
303 // comparisons.
304 if (SecondFalseElement != Overdefined) {
305 // None false -> true.
306 if (FirstFalseElement == Undefined)
307 return replaceInstUsesWith(ICI, Builder.getTrue());
308
309 Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
310
311 // False for one element -> 'i != 47'.
312 if (SecondFalseElement == Undefined)
313 return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
314
315 // False for two elements -> 'i != 47 & i != 72'.
316 Value *C1 = Builder.CreateICmpNE(Idx, FirstFalseIdx);
317 Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
318 Value *C2 = Builder.CreateICmpNE(Idx, SecondFalseIdx);
319 return BinaryOperator::CreateAnd(C1, C2);
320 }
321
322 // If the comparison can be replaced with a range comparison for the elements
323 // where it is true, emit the range check.
324 if (TrueRangeEnd != Overdefined) {
325 assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare")((TrueRangeEnd != FirstTrueElement && "Should emit single compare"
) ? static_cast<void> (0) : __assert_fail ("TrueRangeEnd != FirstTrueElement && \"Should emit single compare\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 325, __PRETTY_FUNCTION__))
;
326
327 // Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
328 if (FirstTrueElement) {
329 Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
330 Idx = Builder.CreateAdd(Idx, Offs);
331 }
332
333 Value *End = ConstantInt::get(Idx->getType(),
334 TrueRangeEnd-FirstTrueElement+1);
335 return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
336 }
337
338 // False range check.
339 if (FalseRangeEnd != Overdefined) {
340 assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare")((FalseRangeEnd != FirstFalseElement && "Should emit single compare"
) ? static_cast<void> (0) : __assert_fail ("FalseRangeEnd != FirstFalseElement && \"Should emit single compare\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 340, __PRETTY_FUNCTION__))
;
341 // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
342 if (FirstFalseElement) {
343 Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
344 Idx = Builder.CreateAdd(Idx, Offs);
345 }
346
347 Value *End = ConstantInt::get(Idx->getType(),
348 FalseRangeEnd-FirstFalseElement);
349 return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
350 }
351
352 // If a magic bitvector captures the entire comparison state
353 // of this load, replace it with computation that does:
354 // ((magic_cst >> i) & 1) != 0
355 {
356 Type *Ty = nullptr;
357
358 // Look for an appropriate type:
359 // - The type of Idx if the magic fits
360 // - The smallest fitting legal type
361 if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
362 Ty = Idx->getType();
363 else
364 Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
365
366 if (Ty) {
367 Value *V = Builder.CreateIntCast(Idx, Ty, false);
368 V = Builder.CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
369 V = Builder.CreateAnd(ConstantInt::get(Ty, 1), V);
370 return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
371 }
372 }
373
374 return nullptr;
375}
376
377/// Return a value that can be used to compare the *offset* implied by a GEP to
378/// zero. For example, if we have &A[i], we want to return 'i' for
379/// "icmp ne i, 0". Note that, in general, indices can be complex, and scales
380/// are involved. The above expression would also be legal to codegen as
381/// "icmp ne (i*4), 0" (assuming A is a pointer to i32).
382/// This latter form is less amenable to optimization though, and we are allowed
383/// to generate the first by knowing that pointer arithmetic doesn't overflow.
384///
385/// If we can't emit an optimized form for this expression, this returns null.
386///
387static Value *evaluateGEPOffsetExpression(User *GEP, InstCombinerImpl &IC,
388 const DataLayout &DL) {
389 gep_type_iterator GTI = gep_type_begin(GEP);
390
391 // Check to see if this gep only has a single variable index. If so, and if
392 // any constant indices are a multiple of its scale, then we can compute this
393 // in terms of the scale of the variable index. For example, if the GEP
394 // implies an offset of "12 + i*4", then we can codegen this as "3 + i",
395 // because the expression will cross zero at the same point.
396 unsigned i, e = GEP->getNumOperands();
397 int64_t Offset = 0;
398 for (i = 1; i != e; ++i, ++GTI) {
399 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
400 // Compute the aggregate offset of constant indices.
401 if (CI->isZero()) continue;
402
403 // Handle a struct index, which adds its field offset to the pointer.
404 if (StructType *STy = GTI.getStructTypeOrNull()) {
405 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
406 } else {
407 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
408 Offset += Size*CI->getSExtValue();
409 }
410 } else {
411 // Found our variable index.
412 break;
413 }
414 }
415
416 // If there are no variable indices, we must have a constant offset, just
417 // evaluate it the general way.
418 if (i == e) return nullptr;
419
420 Value *VariableIdx = GEP->getOperand(i);
421 // Determine the scale factor of the variable element. For example, this is
422 // 4 if the variable index is into an array of i32.
423 uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
424
425 // Verify that there are no other variable indices. If so, emit the hard way.
426 for (++i, ++GTI; i != e; ++i, ++GTI) {
427 ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
428 if (!CI) return nullptr;
429
430 // Compute the aggregate offset of constant indices.
431 if (CI->isZero()) continue;
432
433 // Handle a struct index, which adds its field offset to the pointer.
434 if (StructType *STy = GTI.getStructTypeOrNull()) {
435 Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
436 } else {
437 uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
438 Offset += Size*CI->getSExtValue();
439 }
440 }
441
442 // Okay, we know we have a single variable index, which must be a
443 // pointer/array/vector index. If there is no offset, life is simple, return
444 // the index.
445 Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
446 unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
447 if (Offset == 0) {
448 // Cast to intptrty in case a truncation occurs. If an extension is needed,
449 // we don't need to bother extending: the extension won't affect where the
450 // computation crosses zero.
451 if (VariableIdx->getType()->getPrimitiveSizeInBits().getFixedSize() >
452 IntPtrWidth) {
453 VariableIdx = IC.Builder.CreateTrunc(VariableIdx, IntPtrTy);
454 }
455 return VariableIdx;
456 }
457
458 // Otherwise, there is an index. The computation we will do will be modulo
459 // the pointer size.
460 Offset = SignExtend64(Offset, IntPtrWidth);
461 VariableScale = SignExtend64(VariableScale, IntPtrWidth);
462
463 // To do this transformation, any constant index must be a multiple of the
464 // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
465 // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
466 // multiple of the variable scale.
467 int64_t NewOffs = Offset / (int64_t)VariableScale;
468 if (Offset != NewOffs*(int64_t)VariableScale)
469 return nullptr;
470
471 // Okay, we can do this evaluation. Start by converting the index to intptr.
472 if (VariableIdx->getType() != IntPtrTy)
473 VariableIdx = IC.Builder.CreateIntCast(VariableIdx, IntPtrTy,
474 true /*Signed*/);
475 Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
476 return IC.Builder.CreateAdd(VariableIdx, OffsetVal, "offset");
477}
478
479/// Returns true if we can rewrite Start as a GEP with pointer Base
480/// and some integer offset. The nodes that need to be re-written
481/// for this transformation will be added to Explored.
482static bool canRewriteGEPAsOffset(Value *Start, Value *Base,
483 const DataLayout &DL,
484 SetVector<Value *> &Explored) {
485 SmallVector<Value *, 16> WorkList(1, Start);
486 Explored.insert(Base);
487
488 // The following traversal gives us an order which can be used
489 // when doing the final transformation. Since in the final
490 // transformation we create the PHI replacement instructions first,
491 // we don't have to get them in any particular order.
492 //
493 // However, for other instructions we will have to traverse the
494 // operands of an instruction first, which means that we have to
495 // do a post-order traversal.
496 while (!WorkList.empty()) {
497 SetVector<PHINode *> PHIs;
498
499 while (!WorkList.empty()) {
500 if (Explored.size() >= 100)
501 return false;
502
503 Value *V = WorkList.back();
504
505 if (Explored.contains(V)) {
506 WorkList.pop_back();
507 continue;
508 }
509
510 if (!isa<IntToPtrInst>(V) && !isa<PtrToIntInst>(V) &&
511 !isa<GetElementPtrInst>(V) && !isa<PHINode>(V))
512 // We've found some value that we can't explore which is different from
513 // the base. Therefore we can't do this transformation.
514 return false;
515
516 if (isa<IntToPtrInst>(V) || isa<PtrToIntInst>(V)) {
517 auto *CI = cast<CastInst>(V);
518 if (!CI->isNoopCast(DL))
519 return false;
520
521 if (Explored.count(CI->getOperand(0)) == 0)
522 WorkList.push_back(CI->getOperand(0));
523 }
524
525 if (auto *GEP = dyn_cast<GEPOperator>(V)) {
526 // We're limiting the GEP to having one index. This will preserve
527 // the original pointer type. We could handle more cases in the
528 // future.
529 if (GEP->getNumIndices() != 1 || !GEP->isInBounds() ||
530 GEP->getType() != Start->getType())
531 return false;
532
533 if (Explored.count(GEP->getOperand(0)) == 0)
534 WorkList.push_back(GEP->getOperand(0));
535 }
536
537 if (WorkList.back() == V) {
538 WorkList.pop_back();
539 // We've finished visiting this node, mark it as such.
540 Explored.insert(V);
541 }
542
543 if (auto *PN = dyn_cast<PHINode>(V)) {
544 // We cannot transform PHIs on unsplittable basic blocks.
545 if (isa<CatchSwitchInst>(PN->getParent()->getTerminator()))
546 return false;
547 Explored.insert(PN);
548 PHIs.insert(PN);
549 }
550 }
551
552 // Explore the PHI nodes further.
553 for (auto *PN : PHIs)
554 for (Value *Op : PN->incoming_values())
555 if (Explored.count(Op) == 0)
556 WorkList.push_back(Op);
557 }
558
559 // Make sure that we can do this. Since we can't insert GEPs in a basic
560 // block before a PHI node, we can't easily do this transformation if
561 // we have PHI node users of transformed instructions.
562 for (Value *Val : Explored) {
563 for (Value *Use : Val->uses()) {
564
565 auto *PHI = dyn_cast<PHINode>(Use);
566 auto *Inst = dyn_cast<Instruction>(Val);
567
568 if (Inst == Base || Inst == PHI || !Inst || !PHI ||
569 Explored.count(PHI) == 0)
570 continue;
571
572 if (PHI->getParent() == Inst->getParent())
573 return false;
574 }
575 }
576 return true;
577}
578
579// Sets the appropriate insert point on Builder where we can add
580// a replacement Instruction for V (if that is possible).
581static void setInsertionPoint(IRBuilder<> &Builder, Value *V,
582 bool Before = true) {
583 if (auto *PHI = dyn_cast<PHINode>(V)) {
584 Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt());
585 return;
586 }
587 if (auto *I = dyn_cast<Instruction>(V)) {
588 if (!Before)
589 I = &*std::next(I->getIterator());
590 Builder.SetInsertPoint(I);
591 return;
592 }
593 if (auto *A = dyn_cast<Argument>(V)) {
594 // Set the insertion point in the entry block.
595 BasicBlock &Entry = A->getParent()->getEntryBlock();
596 Builder.SetInsertPoint(&*Entry.getFirstInsertionPt());
597 return;
598 }
599 // Otherwise, this is a constant and we don't need to set a new
600 // insertion point.
601 assert(isa<Constant>(V) && "Setting insertion point for unknown value!")((isa<Constant>(V) && "Setting insertion point for unknown value!"
) ? static_cast<void> (0) : __assert_fail ("isa<Constant>(V) && \"Setting insertion point for unknown value!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 601, __PRETTY_FUNCTION__))
;
602}
603
604/// Returns a re-written value of Start as an indexed GEP using Base as a
605/// pointer.
606static Value *rewriteGEPAsOffset(Value *Start, Value *Base,
607 const DataLayout &DL,
608 SetVector<Value *> &Explored) {
609 // Perform all the substitutions. This is a bit tricky because we can
610 // have cycles in our use-def chains.
611 // 1. Create the PHI nodes without any incoming values.
612 // 2. Create all the other values.
613 // 3. Add the edges for the PHI nodes.
614 // 4. Emit GEPs to get the original pointers.
615 // 5. Remove the original instructions.
616 Type *IndexType = IntegerType::get(
617 Base->getContext(), DL.getIndexTypeSizeInBits(Start->getType()));
618
619 DenseMap<Value *, Value *> NewInsts;
620 NewInsts[Base] = ConstantInt::getNullValue(IndexType);
621
622 // Create the new PHI nodes, without adding any incoming values.
623 for (Value *Val : Explored) {
624 if (Val == Base)
625 continue;
626 // Create empty phi nodes. This avoids cyclic dependencies when creating
627 // the remaining instructions.
628 if (auto *PHI = dyn_cast<PHINode>(Val))
629 NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(),
630 PHI->getName() + ".idx", PHI);
631 }
632 IRBuilder<> Builder(Base->getContext());
633
634 // Create all the other instructions.
635 for (Value *Val : Explored) {
636
637 if (NewInsts.find(Val) != NewInsts.end())
638 continue;
639
640 if (auto *CI = dyn_cast<CastInst>(Val)) {
641 // Don't get rid of the intermediate variable here; the store can grow
642 // the map which will invalidate the reference to the input value.
643 Value *V = NewInsts[CI->getOperand(0)];
644 NewInsts[CI] = V;
645 continue;
646 }
647 if (auto *GEP = dyn_cast<GEPOperator>(Val)) {
648 Value *Index = NewInsts[GEP->getOperand(1)] ? NewInsts[GEP->getOperand(1)]
649 : GEP->getOperand(1);
650 setInsertionPoint(Builder, GEP);
651 // Indices might need to be sign extended. GEPs will magically do
652 // this, but we need to do it ourselves here.
653 if (Index->getType()->getScalarSizeInBits() !=
654 NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) {
655 Index = Builder.CreateSExtOrTrunc(
656 Index, NewInsts[GEP->getOperand(0)]->getType(),
657 GEP->getOperand(0)->getName() + ".sext");
658 }
659
660 auto *Op = NewInsts[GEP->getOperand(0)];
661 if (isa<ConstantInt>(Op) && cast<ConstantInt>(Op)->isZero())
662 NewInsts[GEP] = Index;
663 else
664 NewInsts[GEP] = Builder.CreateNSWAdd(
665 Op, Index, GEP->getOperand(0)->getName() + ".add");
666 continue;
667 }
668 if (isa<PHINode>(Val))
669 continue;
670
671 llvm_unreachable("Unexpected instruction type")::llvm::llvm_unreachable_internal("Unexpected instruction type"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 671)
;
672 }
673
674 // Add the incoming values to the PHI nodes.
675 for (Value *Val : Explored) {
676 if (Val == Base)
677 continue;
678 // All the instructions have been created, we can now add edges to the
679 // phi nodes.
680 if (auto *PHI = dyn_cast<PHINode>(Val)) {
681 PHINode *NewPhi = static_cast<PHINode *>(NewInsts[PHI]);
682 for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) {
683 Value *NewIncoming = PHI->getIncomingValue(I);
684
685 if (NewInsts.find(NewIncoming) != NewInsts.end())
686 NewIncoming = NewInsts[NewIncoming];
687
688 NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I));
689 }
690 }
691 }
692
693 for (Value *Val : Explored) {
694 if (Val == Base)
695 continue;
696
697 // Depending on the type, for external users we have to emit
698 // a GEP or a GEP + ptrtoint.
699 setInsertionPoint(Builder, Val, false);
700
701 // If required, create an inttoptr instruction for Base.
702 Value *NewBase = Base;
703 if (!Base->getType()->isPointerTy())
704 NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(),
705 Start->getName() + "to.ptr");
706
707 Value *GEP = Builder.CreateInBoundsGEP(
708 Start->getType()->getPointerElementType(), NewBase,
709 makeArrayRef(NewInsts[Val]), Val->getName() + ".ptr");
710
711 if (!Val->getType()->isPointerTy()) {
712 Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(),
713 Val->getName() + ".conv");
714 GEP = Cast;
715 }
716 Val->replaceAllUsesWith(GEP);
717 }
718
719 return NewInsts[Start];
720}
721
722/// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express
723/// the input Value as a constant indexed GEP. Returns a pair containing
724/// the GEPs Pointer and Index.
725static std::pair<Value *, Value *>
726getAsConstantIndexedAddress(Value *V, const DataLayout &DL) {
727 Type *IndexType = IntegerType::get(V->getContext(),
728 DL.getIndexTypeSizeInBits(V->getType()));
729
730 Constant *Index = ConstantInt::getNullValue(IndexType);
731 while (true) {
732 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
733 // We accept only inbouds GEPs here to exclude the possibility of
734 // overflow.
735 if (!GEP->isInBounds())
736 break;
737 if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1 &&
738 GEP->getType() == V->getType()) {
739 V = GEP->getOperand(0);
740 Constant *GEPIndex = static_cast<Constant *>(GEP->getOperand(1));
741 Index = ConstantExpr::getAdd(
742 Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType));
743 continue;
744 }
745 break;
746 }
747 if (auto *CI = dyn_cast<IntToPtrInst>(V)) {
748 if (!CI->isNoopCast(DL))
749 break;
750 V = CI->getOperand(0);
751 continue;
752 }
753 if (auto *CI = dyn_cast<PtrToIntInst>(V)) {
754 if (!CI->isNoopCast(DL))
755 break;
756 V = CI->getOperand(0);
757 continue;
758 }
759 break;
760 }
761 return {V, Index};
762}
763
764/// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant.
765/// We can look through PHIs, GEPs and casts in order to determine a common base
766/// between GEPLHS and RHS.
767static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS,
768 ICmpInst::Predicate Cond,
769 const DataLayout &DL) {
770 // FIXME: Support vector of pointers.
771 if (GEPLHS->getType()->isVectorTy())
772 return nullptr;
773
774 if (!GEPLHS->hasAllConstantIndices())
775 return nullptr;
776
777 // Make sure the pointers have the same type.
778 if (GEPLHS->getType() != RHS->getType())
779 return nullptr;
780
781 Value *PtrBase, *Index;
782 std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL);
783
784 // The set of nodes that will take part in this transformation.
785 SetVector<Value *> Nodes;
786
787 if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes))
788 return nullptr;
789
790 // We know we can re-write this as
791 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2)
792 // Since we've only looked through inbouds GEPs we know that we
793 // can't have overflow on either side. We can therefore re-write
794 // this as:
795 // OFFSET1 cmp OFFSET2
796 Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes);
797
798 // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written
799 // GEP having PtrBase as the pointer base, and has returned in NewRHS the
800 // offset. Since Index is the offset of LHS to the base pointer, we will now
801 // compare the offsets instead of comparing the pointers.
802 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS);
803}
804
805/// Fold comparisons between a GEP instruction and something else. At this point
806/// we know that the GEP is on the LHS of the comparison.
807Instruction *InstCombinerImpl::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
808 ICmpInst::Predicate Cond,
809 Instruction &I) {
810 // Don't transform signed compares of GEPs into index compares. Even if the
811 // GEP is inbounds, the final add of the base pointer can have signed overflow
812 // and would change the result of the icmp.
813 // e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
814 // the maximum signed value for the pointer type.
815 if (ICmpInst::isSigned(Cond))
816 return nullptr;
817
818 // Look through bitcasts and addrspacecasts. We do not however want to remove
819 // 0 GEPs.
820 if (!isa<GetElementPtrInst>(RHS))
821 RHS = RHS->stripPointerCasts();
822
823 Value *PtrBase = GEPLHS->getOperand(0);
824 // FIXME: Support vector pointer GEPs.
825 if (PtrBase == RHS && GEPLHS->isInBounds() &&
826 !GEPLHS->getType()->isVectorTy()) {
827 // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
828 // This transformation (ignoring the base and scales) is valid because we
829 // know pointers can't overflow since the gep is inbounds. See if we can
830 // output an optimized form.
831 Value *Offset = evaluateGEPOffsetExpression(GEPLHS, *this, DL);
832
833 // If not, synthesize the offset the hard way.
834 if (!Offset)
835 Offset = EmitGEPOffset(GEPLHS);
836 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
837 Constant::getNullValue(Offset->getType()));
838 }
839
840 if (GEPLHS->isInBounds() && ICmpInst::isEquality(Cond) &&
841 isa<Constant>(RHS) && cast<Constant>(RHS)->isNullValue() &&
842 !NullPointerIsDefined(I.getFunction(),
843 RHS->getType()->getPointerAddressSpace())) {
844 // For most address spaces, an allocation can't be placed at null, but null
845 // itself is treated as a 0 size allocation in the in bounds rules. Thus,
846 // the only valid inbounds address derived from null, is null itself.
847 // Thus, we have four cases to consider:
848 // 1) Base == nullptr, Offset == 0 -> inbounds, null
849 // 2) Base == nullptr, Offset != 0 -> poison as the result is out of bounds
850 // 3) Base != nullptr, Offset == (-base) -> poison (crossing allocations)
851 // 4) Base != nullptr, Offset != (-base) -> nonnull (and possibly poison)
852 //
853 // (Note if we're indexing a type of size 0, that simply collapses into one
854 // of the buckets above.)
855 //
856 // In general, we're allowed to make values less poison (i.e. remove
857 // sources of full UB), so in this case, we just select between the two
858 // non-poison cases (1 and 4 above).
859 //
860 // For vectors, we apply the same reasoning on a per-lane basis.
861 auto *Base = GEPLHS->getPointerOperand();
862 if (GEPLHS->getType()->isVectorTy() && Base->getType()->isPointerTy()) {
863 auto EC = cast<VectorType>(GEPLHS->getType())->getElementCount();
864 Base = Builder.CreateVectorSplat(EC, Base);
865 }
866 return new ICmpInst(Cond, Base,
867 ConstantExpr::getPointerBitCastOrAddrSpaceCast(
868 cast<Constant>(RHS), Base->getType()));
869 } else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
870 // If the base pointers are different, but the indices are the same, just
871 // compare the base pointer.
872 if (PtrBase != GEPRHS->getOperand(0)) {
873 bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
874 IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
875 GEPRHS->getOperand(0)->getType();
876 if (IndicesTheSame)
877 for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
878 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
879 IndicesTheSame = false;
880 break;
881 }
882
883 // If all indices are the same, just compare the base pointers.
884 Type *BaseType = GEPLHS->getOperand(0)->getType();
885 if (IndicesTheSame && CmpInst::makeCmpResultType(BaseType) == I.getType())
886 return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
887
888 // If we're comparing GEPs with two base pointers that only differ in type
889 // and both GEPs have only constant indices or just one use, then fold
890 // the compare with the adjusted indices.
891 // FIXME: Support vector of pointers.
892 if (GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
893 (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
894 (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
895 PtrBase->stripPointerCasts() ==
896 GEPRHS->getOperand(0)->stripPointerCasts() &&
897 !GEPLHS->getType()->isVectorTy()) {
898 Value *LOffset = EmitGEPOffset(GEPLHS);
899 Value *ROffset = EmitGEPOffset(GEPRHS);
900
901 // If we looked through an addrspacecast between different sized address
902 // spaces, the LHS and RHS pointers are different sized
903 // integers. Truncate to the smaller one.
904 Type *LHSIndexTy = LOffset->getType();
905 Type *RHSIndexTy = ROffset->getType();
906 if (LHSIndexTy != RHSIndexTy) {
907 if (LHSIndexTy->getPrimitiveSizeInBits().getFixedSize() <
908 RHSIndexTy->getPrimitiveSizeInBits().getFixedSize()) {
909 ROffset = Builder.CreateTrunc(ROffset, LHSIndexTy);
910 } else
911 LOffset = Builder.CreateTrunc(LOffset, RHSIndexTy);
912 }
913
914 Value *Cmp = Builder.CreateICmp(ICmpInst::getSignedPredicate(Cond),
915 LOffset, ROffset);
916 return replaceInstUsesWith(I, Cmp);
917 }
918
919 // Otherwise, the base pointers are different and the indices are
920 // different. Try convert this to an indexed compare by looking through
921 // PHIs/casts.
922 return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
923 }
924
925 // If one of the GEPs has all zero indices, recurse.
926 // FIXME: Handle vector of pointers.
927 if (!GEPLHS->getType()->isVectorTy() && GEPLHS->hasAllZeroIndices())
928 return foldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
929 ICmpInst::getSwappedPredicate(Cond), I);
930
931 // If the other GEP has all zero indices, recurse.
932 // FIXME: Handle vector of pointers.
933 if (!GEPRHS->getType()->isVectorTy() && GEPRHS->hasAllZeroIndices())
934 return foldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
935
936 bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
937 if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
938 // If the GEPs only differ by one index, compare it.
939 unsigned NumDifferences = 0; // Keep track of # differences.
940 unsigned DiffOperand = 0; // The operand that differs.
941 for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
942 if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
943 Type *LHSType = GEPLHS->getOperand(i)->getType();
944 Type *RHSType = GEPRHS->getOperand(i)->getType();
945 // FIXME: Better support for vector of pointers.
946 if (LHSType->getPrimitiveSizeInBits() !=
947 RHSType->getPrimitiveSizeInBits() ||
948 (GEPLHS->getType()->isVectorTy() &&
949 (!LHSType->isVectorTy() || !RHSType->isVectorTy()))) {
950 // Irreconcilable differences.
951 NumDifferences = 2;
952 break;
953 }
954
955 if (NumDifferences++) break;
956 DiffOperand = i;
957 }
958
959 if (NumDifferences == 0) // SAME GEP?
960 return replaceInstUsesWith(I, // No comparison is needed here.
961 ConstantInt::get(I.getType(), ICmpInst::isTrueWhenEqual(Cond)));
962
963 else if (NumDifferences == 1 && GEPsInBounds) {
964 Value *LHSV = GEPLHS->getOperand(DiffOperand);
965 Value *RHSV = GEPRHS->getOperand(DiffOperand);
966 // Make sure we do a signed comparison here.
967 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
968 }
969 }
970
971 // Only lower this if the icmp is the only user of the GEP or if we expect
972 // the result to fold to a constant!
973 if (GEPsInBounds && (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
974 (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
975 // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
976 Value *L = EmitGEPOffset(GEPLHS);
977 Value *R = EmitGEPOffset(GEPRHS);
978 return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
979 }
980 }
981
982 // Try convert this to an indexed compare by looking through PHIs/casts as a
983 // last resort.
984 return transformToIndexedCompare(GEPLHS, RHS, Cond, DL);
985}
986
987Instruction *InstCombinerImpl::foldAllocaCmp(ICmpInst &ICI,
988 const AllocaInst *Alloca,
989 const Value *Other) {
990 assert(ICI.isEquality() && "Cannot fold non-equality comparison.")((ICI.isEquality() && "Cannot fold non-equality comparison."
) ? static_cast<void> (0) : __assert_fail ("ICI.isEquality() && \"Cannot fold non-equality comparison.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 990, __PRETTY_FUNCTION__))
;
991
992 // It would be tempting to fold away comparisons between allocas and any
993 // pointer not based on that alloca (e.g. an argument). However, even
994 // though such pointers cannot alias, they can still compare equal.
995 //
996 // But LLVM doesn't specify where allocas get their memory, so if the alloca
997 // doesn't escape we can argue that it's impossible to guess its value, and we
998 // can therefore act as if any such guesses are wrong.
999 //
1000 // The code below checks that the alloca doesn't escape, and that it's only
1001 // used in a comparison once (the current instruction). The
1002 // single-comparison-use condition ensures that we're trivially folding all
1003 // comparisons against the alloca consistently, and avoids the risk of
1004 // erroneously folding a comparison of the pointer with itself.
1005
1006 unsigned MaxIter = 32; // Break cycles and bound to constant-time.
1007
1008 SmallVector<const Use *, 32> Worklist;
1009 for (const Use &U : Alloca->uses()) {
1010 if (Worklist.size() >= MaxIter)
1011 return nullptr;
1012 Worklist.push_back(&U);
1013 }
1014
1015 unsigned NumCmps = 0;
1016 while (!Worklist.empty()) {
1017 assert(Worklist.size() <= MaxIter)((Worklist.size() <= MaxIter) ? static_cast<void> (0
) : __assert_fail ("Worklist.size() <= MaxIter", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1017, __PRETTY_FUNCTION__))
;
1018 const Use *U = Worklist.pop_back_val();
1019 const Value *V = U->getUser();
1020 --MaxIter;
1021
1022 if (isa<BitCastInst>(V) || isa<GetElementPtrInst>(V) || isa<PHINode>(V) ||
1023 isa<SelectInst>(V)) {
1024 // Track the uses.
1025 } else if (isa<LoadInst>(V)) {
1026 // Loading from the pointer doesn't escape it.
1027 continue;
1028 } else if (const auto *SI = dyn_cast<StoreInst>(V)) {
1029 // Storing *to* the pointer is fine, but storing the pointer escapes it.
1030 if (SI->getValueOperand() == U->get())
1031 return nullptr;
1032 continue;
1033 } else if (isa<ICmpInst>(V)) {
1034 if (NumCmps++)
1035 return nullptr; // Found more than one cmp.
1036 continue;
1037 } else if (const auto *Intrin = dyn_cast<IntrinsicInst>(V)) {
1038 switch (Intrin->getIntrinsicID()) {
1039 // These intrinsics don't escape or compare the pointer. Memset is safe
1040 // because we don't allow ptrtoint. Memcpy and memmove are safe because
1041 // we don't allow stores, so src cannot point to V.
1042 case Intrinsic::lifetime_start: case Intrinsic::lifetime_end:
1043 case Intrinsic::memcpy: case Intrinsic::memmove: case Intrinsic::memset:
1044 continue;
1045 default:
1046 return nullptr;
1047 }
1048 } else {
1049 return nullptr;
1050 }
1051 for (const Use &U : V->uses()) {
1052 if (Worklist.size() >= MaxIter)
1053 return nullptr;
1054 Worklist.push_back(&U);
1055 }
1056 }
1057
1058 Type *CmpTy = CmpInst::makeCmpResultType(Other->getType());
1059 return replaceInstUsesWith(
1060 ICI,
1061 ConstantInt::get(CmpTy, !CmpInst::isTrueWhenEqual(ICI.getPredicate())));
1062}
1063
1064/// Fold "icmp pred (X+C), X".
1065Instruction *InstCombinerImpl::foldICmpAddOpConst(Value *X, const APInt &C,
1066 ICmpInst::Predicate Pred) {
1067 // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
1068 // so the values can never be equal. Similarly for all other "or equals"
1069 // operators.
1070 assert(!!C && "C should not be zero!")((!!C && "C should not be zero!") ? static_cast<void
> (0) : __assert_fail ("!!C && \"C should not be zero!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1070, __PRETTY_FUNCTION__))
;
1071
1072 // (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
1073 // (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
1074 // (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
1075 if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
1076 Constant *R = ConstantInt::get(X->getType(),
1077 APInt::getMaxValue(C.getBitWidth()) - C);
1078 return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
1079 }
1080
1081 // (X+1) >u X --> X <u (0-1) --> X != 255
1082 // (X+2) >u X --> X <u (0-2) --> X <u 254
1083 // (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
1084 if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
1085 return new ICmpInst(ICmpInst::ICMP_ULT, X,
1086 ConstantInt::get(X->getType(), -C));
1087
1088 APInt SMax = APInt::getSignedMaxValue(C.getBitWidth());
1089
1090 // (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
1091 // (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
1092 // (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
1093 // (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
1094 // (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
1095 // (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
1096 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
1097 return new ICmpInst(ICmpInst::ICMP_SGT, X,
1098 ConstantInt::get(X->getType(), SMax - C));
1099
1100 // (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
1101 // (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
1102 // (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
1103 // (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
1104 // (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
1105 // (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
1106
1107 assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)((Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) ?
static_cast<void> (0) : __assert_fail ("Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1107, __PRETTY_FUNCTION__))
;
1108 return new ICmpInst(ICmpInst::ICMP_SLT, X,
1109 ConstantInt::get(X->getType(), SMax - (C - 1)));
1110}
1111
1112/// Handle "(icmp eq/ne (ashr/lshr AP2, A), AP1)" ->
1113/// (icmp eq/ne A, Log2(AP2/AP1)) ->
1114/// (icmp eq/ne A, Log2(AP2) - Log2(AP1)).
1115Instruction *InstCombinerImpl::foldICmpShrConstConst(ICmpInst &I, Value *A,
1116 const APInt &AP1,
1117 const APInt &AP2) {
1118 assert(I.isEquality() && "Cannot fold icmp gt/lt")((I.isEquality() && "Cannot fold icmp gt/lt") ? static_cast
<void> (0) : __assert_fail ("I.isEquality() && \"Cannot fold icmp gt/lt\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1118, __PRETTY_FUNCTION__))
;
1119
1120 auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1121 if (I.getPredicate() == I.ICMP_NE)
1122 Pred = CmpInst::getInversePredicate(Pred);
1123 return new ICmpInst(Pred, LHS, RHS);
1124 };
1125
1126 // Don't bother doing any work for cases which InstSimplify handles.
1127 if (AP2.isNullValue())
1128 return nullptr;
1129
1130 bool IsAShr = isa<AShrOperator>(I.getOperand(0));
1131 if (IsAShr) {
1132 if (AP2.isAllOnesValue())
1133 return nullptr;
1134 if (AP2.isNegative() != AP1.isNegative())
1135 return nullptr;
1136 if (AP2.sgt(AP1))
1137 return nullptr;
1138 }
1139
1140 if (!AP1)
1141 // 'A' must be large enough to shift out the highest set bit.
1142 return getICmp(I.ICMP_UGT, A,
1143 ConstantInt::get(A->getType(), AP2.logBase2()));
1144
1145 if (AP1 == AP2)
1146 return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1147
1148 int Shift;
1149 if (IsAShr && AP1.isNegative())
1150 Shift = AP1.countLeadingOnes() - AP2.countLeadingOnes();
1151 else
1152 Shift = AP1.countLeadingZeros() - AP2.countLeadingZeros();
1153
1154 if (Shift > 0) {
1155 if (IsAShr && AP1 == AP2.ashr(Shift)) {
1156 // There are multiple solutions if we are comparing against -1 and the LHS
1157 // of the ashr is not a power of two.
1158 if (AP1.isAllOnesValue() && !AP2.isPowerOf2())
1159 return getICmp(I.ICMP_UGE, A, ConstantInt::get(A->getType(), Shift));
1160 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1161 } else if (AP1 == AP2.lshr(Shift)) {
1162 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1163 }
1164 }
1165
1166 // Shifting const2 will never be equal to const1.
1167 // FIXME: This should always be handled by InstSimplify?
1168 auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
1169 return replaceInstUsesWith(I, TorF);
1170}
1171
1172/// Handle "(icmp eq/ne (shl AP2, A), AP1)" ->
1173/// (icmp eq/ne A, TrailingZeros(AP1) - TrailingZeros(AP2)).
1174Instruction *InstCombinerImpl::foldICmpShlConstConst(ICmpInst &I, Value *A,
1175 const APInt &AP1,
1176 const APInt &AP2) {
1177 assert(I.isEquality() && "Cannot fold icmp gt/lt")((I.isEquality() && "Cannot fold icmp gt/lt") ? static_cast
<void> (0) : __assert_fail ("I.isEquality() && \"Cannot fold icmp gt/lt\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1177, __PRETTY_FUNCTION__))
;
1178
1179 auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {
1180 if (I.getPredicate() == I.ICMP_NE)
1181 Pred = CmpInst::getInversePredicate(Pred);
1182 return new ICmpInst(Pred, LHS, RHS);
1183 };
1184
1185 // Don't bother doing any work for cases which InstSimplify handles.
1186 if (AP2.isNullValue())
1187 return nullptr;
1188
1189 unsigned AP2TrailingZeros = AP2.countTrailingZeros();
1190
1191 if (!AP1 && AP2TrailingZeros != 0)
1192 return getICmp(
1193 I.ICMP_UGE, A,
1194 ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros));
1195
1196 if (AP1 == AP2)
1197 return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));
1198
1199 // Get the distance between the lowest bits that are set.
1200 int Shift = AP1.countTrailingZeros() - AP2TrailingZeros;
1201
1202 if (Shift > 0 && AP2.shl(Shift) == AP1)
1203 return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));
1204
1205 // Shifting const2 will never be equal to const1.
1206 // FIXME: This should always be handled by InstSimplify?
1207 auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE);
1208 return replaceInstUsesWith(I, TorF);
1209}
1210
1211/// The caller has matched a pattern of the form:
1212/// I = icmp ugt (add (add A, B), CI2), CI1
1213/// If this is of the form:
1214/// sum = a + b
1215/// if (sum+128 >u 255)
1216/// Then replace it with llvm.sadd.with.overflow.i8.
1217///
1218static Instruction *processUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
1219 ConstantInt *CI2, ConstantInt *CI1,
1220 InstCombinerImpl &IC) {
1221 // The transformation we're trying to do here is to transform this into an
1222 // llvm.sadd.with.overflow. To do this, we have to replace the original add
1223 // with a narrower add, and discard the add-with-constant that is part of the
1224 // range check (if we can't eliminate it, this isn't profitable).
1225
1226 // In order to eliminate the add-with-constant, the compare can be its only
1227 // use.
1228 Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
1229 if (!AddWithCst->hasOneUse())
1230 return nullptr;
1231
1232 // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
1233 if (!CI2->getValue().isPowerOf2())
1234 return nullptr;
1235 unsigned NewWidth = CI2->getValue().countTrailingZeros();
1236 if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31)
1237 return nullptr;
1238
1239 // The width of the new add formed is 1 more than the bias.
1240 ++NewWidth;
1241
1242 // Check to see that CI1 is an all-ones value with NewWidth bits.
1243 if (CI1->getBitWidth() == NewWidth ||
1244 CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
1245 return nullptr;
1246
1247 // This is only really a signed overflow check if the inputs have been
1248 // sign-extended; check for that condition. For example, if CI2 is 2^31 and
1249 // the operands of the add are 64 bits wide, we need at least 33 sign bits.
1250 unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
1251 if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits ||
1252 IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits)
1253 return nullptr;
1254
1255 // In order to replace the original add with a narrower
1256 // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
1257 // and truncates that discard the high bits of the add. Verify that this is
1258 // the case.
1259 Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
1260 for (User *U : OrigAdd->users()) {
1261 if (U == AddWithCst)
1262 continue;
1263
1264 // Only accept truncates for now. We would really like a nice recursive
1265 // predicate like SimplifyDemandedBits, but which goes downwards the use-def
1266 // chain to see which bits of a value are actually demanded. If the
1267 // original add had another add which was then immediately truncated, we
1268 // could still do the transformation.
1269 TruncInst *TI = dyn_cast<TruncInst>(U);
1270 if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth)
1271 return nullptr;
1272 }
1273
1274 // If the pattern matches, truncate the inputs to the narrower type and
1275 // use the sadd_with_overflow intrinsic to efficiently compute both the
1276 // result and the overflow bit.
1277 Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
1278 Function *F = Intrinsic::getDeclaration(
1279 I.getModule(), Intrinsic::sadd_with_overflow, NewType);
1280
1281 InstCombiner::BuilderTy &Builder = IC.Builder;
1282
1283 // Put the new code above the original add, in case there are any uses of the
1284 // add between the add and the compare.
1285 Builder.SetInsertPoint(OrigAdd);
1286
1287 Value *TruncA = Builder.CreateTrunc(A, NewType, A->getName() + ".trunc");
1288 Value *TruncB = Builder.CreateTrunc(B, NewType, B->getName() + ".trunc");
1289 CallInst *Call = Builder.CreateCall(F, {TruncA, TruncB}, "sadd");
1290 Value *Add = Builder.CreateExtractValue(Call, 0, "sadd.result");
1291 Value *ZExt = Builder.CreateZExt(Add, OrigAdd->getType());
1292
1293 // The inner add was the result of the narrow add, zero extended to the
1294 // wider type. Replace it with the result computed by the intrinsic.
1295 IC.replaceInstUsesWith(*OrigAdd, ZExt);
1296 IC.eraseInstFromFunction(*OrigAdd);
1297
1298 // The original icmp gets replaced with the overflow value.
1299 return ExtractValueInst::Create(Call, 1, "sadd.overflow");
1300}
1301
1302/// If we have:
1303/// icmp eq/ne (urem/srem %x, %y), 0
1304/// iff %y is a power-of-two, we can replace this with a bit test:
1305/// icmp eq/ne (and %x, (add %y, -1)), 0
1306Instruction *InstCombinerImpl::foldIRemByPowerOfTwoToBitTest(ICmpInst &I) {
1307 // This fold is only valid for equality predicates.
1308 if (!I.isEquality())
1309 return nullptr;
1310 ICmpInst::Predicate Pred;
1311 Value *X, *Y, *Zero;
1312 if (!match(&I, m_ICmp(Pred, m_OneUse(m_IRem(m_Value(X), m_Value(Y))),
1313 m_CombineAnd(m_Zero(), m_Value(Zero)))))
1314 return nullptr;
1315 if (!isKnownToBeAPowerOfTwo(Y, /*OrZero*/ true, 0, &I))
1316 return nullptr;
1317 // This may increase instruction count, we don't enforce that Y is a constant.
1318 Value *Mask = Builder.CreateAdd(Y, Constant::getAllOnesValue(Y->getType()));
1319 Value *Masked = Builder.CreateAnd(X, Mask);
1320 return ICmpInst::Create(Instruction::ICmp, Pred, Masked, Zero);
1321}
1322
1323/// Fold equality-comparison between zero and any (maybe truncated) right-shift
1324/// by one-less-than-bitwidth into a sign test on the original value.
1325Instruction *InstCombinerImpl::foldSignBitTest(ICmpInst &I) {
1326 Instruction *Val;
1327 ICmpInst::Predicate Pred;
1328 if (!I.isEquality() || !match(&I, m_ICmp(Pred, m_Instruction(Val), m_Zero())))
1329 return nullptr;
1330
1331 Value *X;
1332 Type *XTy;
1333
1334 Constant *C;
1335 if (match(Val, m_TruncOrSelf(m_Shr(m_Value(X), m_Constant(C))))) {
1336 XTy = X->getType();
1337 unsigned XBitWidth = XTy->getScalarSizeInBits();
1338 if (!match(C, m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_EQ,
1339 APInt(XBitWidth, XBitWidth - 1))))
1340 return nullptr;
1341 } else if (isa<BinaryOperator>(Val) &&
1342 (X = reassociateShiftAmtsOfTwoSameDirectionShifts(
1343 cast<BinaryOperator>(Val), SQ.getWithInstruction(Val),
1344 /*AnalyzeForSignBitExtraction=*/true))) {
1345 XTy = X->getType();
1346 } else
1347 return nullptr;
1348
1349 return ICmpInst::Create(Instruction::ICmp,
1350 Pred == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_SGE
1351 : ICmpInst::ICMP_SLT,
1352 X, ConstantInt::getNullValue(XTy));
1353}
1354
1355// Handle icmp pred X, 0
1356Instruction *InstCombinerImpl::foldICmpWithZero(ICmpInst &Cmp) {
1357 CmpInst::Predicate Pred = Cmp.getPredicate();
1358 if (!match(Cmp.getOperand(1), m_Zero()))
1359 return nullptr;
1360
1361 // (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0)
1362 if (Pred == ICmpInst::ICMP_SGT) {
1363 Value *A, *B;
1364 SelectPatternResult SPR = matchSelectPattern(Cmp.getOperand(0), A, B);
1365 if (SPR.Flavor == SPF_SMIN) {
1366 if (isKnownPositive(A, DL, 0, &AC, &Cmp, &DT))
1367 return new ICmpInst(Pred, B, Cmp.getOperand(1));
1368 if (isKnownPositive(B, DL, 0, &AC, &Cmp, &DT))
1369 return new ICmpInst(Pred, A, Cmp.getOperand(1));
1370 }
1371 }
1372
1373 if (Instruction *New = foldIRemByPowerOfTwoToBitTest(Cmp))
1374 return New;
1375
1376 // Given:
1377 // icmp eq/ne (urem %x, %y), 0
1378 // Iff %x has 0 or 1 bits set, and %y has at least 2 bits set, omit 'urem':
1379 // icmp eq/ne %x, 0
1380 Value *X, *Y;
1381 if (match(Cmp.getOperand(0), m_URem(m_Value(X), m_Value(Y))) &&
1382 ICmpInst::isEquality(Pred)) {
1383 KnownBits XKnown = computeKnownBits(X, 0, &Cmp);
1384 KnownBits YKnown = computeKnownBits(Y, 0, &Cmp);
1385 if (XKnown.countMaxPopulation() == 1 && YKnown.countMinPopulation() >= 2)
1386 return new ICmpInst(Pred, X, Cmp.getOperand(1));
1387 }
1388
1389 return nullptr;
1390}
1391
1392/// Fold icmp Pred X, C.
1393/// TODO: This code structure does not make sense. The saturating add fold
1394/// should be moved to some other helper and extended as noted below (it is also
1395/// possible that code has been made unnecessary - do we canonicalize IR to
1396/// overflow/saturating intrinsics or not?).
1397Instruction *InstCombinerImpl::foldICmpWithConstant(ICmpInst &Cmp) {
1398 // Match the following pattern, which is a common idiom when writing
1399 // overflow-safe integer arithmetic functions. The source performs an addition
1400 // in wider type and explicitly checks for overflow using comparisons against
1401 // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic.
1402 //
1403 // TODO: This could probably be generalized to handle other overflow-safe
1404 // operations if we worked out the formulas to compute the appropriate magic
1405 // constants.
1406 //
1407 // sum = a + b
1408 // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
1409 CmpInst::Predicate Pred = Cmp.getPredicate();
1410 Value *Op0 = Cmp.getOperand(0), *Op1 = Cmp.getOperand(1);
1411 Value *A, *B;
1412 ConstantInt *CI, *CI2; // I = icmp ugt (add (add A, B), CI2), CI
1413 if (Pred == ICmpInst::ICMP_UGT && match(Op1, m_ConstantInt(CI)) &&
1414 match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
1415 if (Instruction *Res = processUGT_ADDCST_ADD(Cmp, A, B, CI2, CI, *this))
1416 return Res;
1417
1418 // icmp(phi(C1, C2, ...), C) -> phi(icmp(C1, C), icmp(C2, C), ...).
1419 Constant *C = dyn_cast<Constant>(Op1);
1420 if (!C)
1421 return nullptr;
1422
1423 if (auto *Phi = dyn_cast<PHINode>(Op0))
1424 if (all_of(Phi->operands(), [](Value *V) { return isa<Constant>(V); })) {
1425 Type *Ty = Cmp.getType();
1426 Builder.SetInsertPoint(Phi);
1427 PHINode *NewPhi =
1428 Builder.CreatePHI(Ty, Phi->getNumOperands());
1429 for (BasicBlock *Predecessor : predecessors(Phi->getParent())) {
1430 auto *Input =
1431 cast<Constant>(Phi->getIncomingValueForBlock(Predecessor));
1432 auto *BoolInput = ConstantExpr::getCompare(Pred, Input, C);
1433 NewPhi->addIncoming(BoolInput, Predecessor);
1434 }
1435 NewPhi->takeName(&Cmp);
1436 return replaceInstUsesWith(Cmp, NewPhi);
1437 }
1438
1439 return nullptr;
1440}
1441
1442/// Canonicalize icmp instructions based on dominating conditions.
1443Instruction *InstCombinerImpl::foldICmpWithDominatingICmp(ICmpInst &Cmp) {
1444 // This is a cheap/incomplete check for dominance - just match a single
1445 // predecessor with a conditional branch.
1446 BasicBlock *CmpBB = Cmp.getParent();
1447 BasicBlock *DomBB = CmpBB->getSinglePredecessor();
1448 if (!DomBB)
1449 return nullptr;
1450
1451 Value *DomCond;
1452 BasicBlock *TrueBB, *FalseBB;
1453 if (!match(DomBB->getTerminator(), m_Br(m_Value(DomCond), TrueBB, FalseBB)))
1454 return nullptr;
1455
1456 assert((TrueBB == CmpBB || FalseBB == CmpBB) &&(((TrueBB == CmpBB || FalseBB == CmpBB) && "Predecessor block does not point to successor?"
) ? static_cast<void> (0) : __assert_fail ("(TrueBB == CmpBB || FalseBB == CmpBB) && \"Predecessor block does not point to successor?\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1457, __PRETTY_FUNCTION__))
1457 "Predecessor block does not point to successor?")(((TrueBB == CmpBB || FalseBB == CmpBB) && "Predecessor block does not point to successor?"
) ? static_cast<void> (0) : __assert_fail ("(TrueBB == CmpBB || FalseBB == CmpBB) && \"Predecessor block does not point to successor?\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1457, __PRETTY_FUNCTION__))
;
1458
1459 // The branch should get simplified. Don't bother simplifying this condition.
1460 if (TrueBB == FalseBB)
1461 return nullptr;
1462
1463 // Try to simplify this compare to T/F based on the dominating condition.
1464 Optional<bool> Imp = isImpliedCondition(DomCond, &Cmp, DL, TrueBB == CmpBB);
1465 if (Imp)
1466 return replaceInstUsesWith(Cmp, ConstantInt::get(Cmp.getType(), *Imp));
1467
1468 CmpInst::Predicate Pred = Cmp.getPredicate();
1469 Value *X = Cmp.getOperand(0), *Y = Cmp.getOperand(1);
1470 ICmpInst::Predicate DomPred;
1471 const APInt *C, *DomC;
1472 if (match(DomCond, m_ICmp(DomPred, m_Specific(X), m_APInt(DomC))) &&
1473 match(Y, m_APInt(C))) {
1474 // We have 2 compares of a variable with constants. Calculate the constant
1475 // ranges of those compares to see if we can transform the 2nd compare:
1476 // DomBB:
1477 // DomCond = icmp DomPred X, DomC
1478 // br DomCond, CmpBB, FalseBB
1479 // CmpBB:
1480 // Cmp = icmp Pred X, C
1481 ConstantRange CR = ConstantRange::makeAllowedICmpRegion(Pred, *C);
1482 ConstantRange DominatingCR =
1483 (CmpBB == TrueBB) ? ConstantRange::makeExactICmpRegion(DomPred, *DomC)
1484 : ConstantRange::makeExactICmpRegion(
1485 CmpInst::getInversePredicate(DomPred), *DomC);
1486 ConstantRange Intersection = DominatingCR.intersectWith(CR);
1487 ConstantRange Difference = DominatingCR.difference(CR);
1488 if (Intersection.isEmptySet())
1489 return replaceInstUsesWith(Cmp, Builder.getFalse());
1490 if (Difference.isEmptySet())
1491 return replaceInstUsesWith(Cmp, Builder.getTrue());
1492
1493 // Canonicalizing a sign bit comparison that gets used in a branch,
1494 // pessimizes codegen by generating branch on zero instruction instead
1495 // of a test and branch. So we avoid canonicalizing in such situations
1496 // because test and branch instruction has better branch displacement
1497 // than compare and branch instruction.
1498 bool UnusedBit;
1499 bool IsSignBit = isSignBitCheck(Pred, *C, UnusedBit);
1500 if (Cmp.isEquality() || (IsSignBit && hasBranchUse(Cmp)))
1501 return nullptr;
1502
1503 if (const APInt *EqC = Intersection.getSingleElement())
1504 return new ICmpInst(ICmpInst::ICMP_EQ, X, Builder.getInt(*EqC));
1505 if (const APInt *NeC = Difference.getSingleElement())
1506 return new ICmpInst(ICmpInst::ICMP_NE, X, Builder.getInt(*NeC));
1507 }
1508
1509 return nullptr;
1510}
1511
1512/// Fold icmp (trunc X, Y), C.
1513Instruction *InstCombinerImpl::foldICmpTruncConstant(ICmpInst &Cmp,
1514 TruncInst *Trunc,
1515 const APInt &C) {
1516 ICmpInst::Predicate Pred = Cmp.getPredicate();
1517 Value *X = Trunc->getOperand(0);
1518 if (C.isOneValue() && C.getBitWidth() > 1) {
1519 // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1
1520 Value *V = nullptr;
1521 if (Pred == ICmpInst::ICMP_SLT && match(X, m_Signum(m_Value(V))))
1522 return new ICmpInst(ICmpInst::ICMP_SLT, V,
1523 ConstantInt::get(V->getType(), 1));
1524 }
1525
1526 if (Cmp.isEquality() && Trunc->hasOneUse()) {
1527 // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
1528 // of the high bits truncated out of x are known.
1529 unsigned DstBits = Trunc->getType()->getScalarSizeInBits(),
1530 SrcBits = X->getType()->getScalarSizeInBits();
1531 KnownBits Known = computeKnownBits(X, 0, &Cmp);
1532
1533 // If all the high bits are known, we can do this xform.
1534 if ((Known.Zero | Known.One).countLeadingOnes() >= SrcBits - DstBits) {
1535 // Pull in the high bits from known-ones set.
1536 APInt NewRHS = C.zext(SrcBits);
1537 NewRHS |= Known.One & APInt::getHighBitsSet(SrcBits, SrcBits - DstBits);
1538 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), NewRHS));
1539 }
1540 }
1541
1542 return nullptr;
1543}
1544
1545/// Fold icmp (xor X, Y), C.
1546Instruction *InstCombinerImpl::foldICmpXorConstant(ICmpInst &Cmp,
1547 BinaryOperator *Xor,
1548 const APInt &C) {
1549 Value *X = Xor->getOperand(0);
1550 Value *Y = Xor->getOperand(1);
1551 const APInt *XorC;
1552 if (!match(Y, m_APInt(XorC)))
1553 return nullptr;
1554
1555 // If this is a comparison that tests the signbit (X < 0) or (x > -1),
1556 // fold the xor.
1557 ICmpInst::Predicate Pred = Cmp.getPredicate();
1558 bool TrueIfSigned = false;
1559 if (isSignBitCheck(Cmp.getPredicate(), C, TrueIfSigned)) {
1560
1561 // If the sign bit of the XorCst is not set, there is no change to
1562 // the operation, just stop using the Xor.
1563 if (!XorC->isNegative())
1564 return replaceOperand(Cmp, 0, X);
1565
1566 // Emit the opposite comparison.
1567 if (TrueIfSigned)
1568 return new ICmpInst(ICmpInst::ICMP_SGT, X,
1569 ConstantInt::getAllOnesValue(X->getType()));
1570 else
1571 return new ICmpInst(ICmpInst::ICMP_SLT, X,
1572 ConstantInt::getNullValue(X->getType()));
1573 }
1574
1575 if (Xor->hasOneUse()) {
1576 // (icmp u/s (xor X SignMask), C) -> (icmp s/u X, (xor C SignMask))
1577 if (!Cmp.isEquality() && XorC->isSignMask()) {
1578 Pred = Cmp.getFlippedSignednessPredicate();
1579 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
1580 }
1581
1582 // (icmp u/s (xor X ~SignMask), C) -> (icmp s/u X, (xor C ~SignMask))
1583 if (!Cmp.isEquality() && XorC->isMaxSignedValue()) {
1584 Pred = Cmp.getFlippedSignednessPredicate();
1585 Pred = Cmp.getSwappedPredicate(Pred);
1586 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), C ^ *XorC));
1587 }
1588 }
1589
1590 // Mask constant magic can eliminate an 'xor' with unsigned compares.
1591 if (Pred == ICmpInst::ICMP_UGT) {
1592 // (xor X, ~C) >u C --> X <u ~C (when C+1 is a power of 2)
1593 if (*XorC == ~C && (C + 1).isPowerOf2())
1594 return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
1595 // (xor X, C) >u C --> X >u C (when C+1 is a power of 2)
1596 if (*XorC == C && (C + 1).isPowerOf2())
1597 return new ICmpInst(ICmpInst::ICMP_UGT, X, Y);
1598 }
1599 if (Pred == ICmpInst::ICMP_ULT) {
1600 // (xor X, -C) <u C --> X >u ~C (when C is a power of 2)
1601 if (*XorC == -C && C.isPowerOf2())
1602 return new ICmpInst(ICmpInst::ICMP_UGT, X,
1603 ConstantInt::get(X->getType(), ~C));
1604 // (xor X, C) <u C --> X >u ~C (when -C is a power of 2)
1605 if (*XorC == C && (-C).isPowerOf2())
1606 return new ICmpInst(ICmpInst::ICMP_UGT, X,
1607 ConstantInt::get(X->getType(), ~C));
1608 }
1609 return nullptr;
1610}
1611
1612/// Fold icmp (and (sh X, Y), C2), C1.
1613Instruction *InstCombinerImpl::foldICmpAndShift(ICmpInst &Cmp,
1614 BinaryOperator *And,
1615 const APInt &C1,
1616 const APInt &C2) {
1617 BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
1618 if (!Shift || !Shift->isShift())
1619 return nullptr;
1620
1621 // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could
1622 // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in
1623 // code produced by the clang front-end, for bitfield access.
1624 // This seemingly simple opportunity to fold away a shift turns out to be
1625 // rather complicated. See PR17827 for details.
1626 unsigned ShiftOpcode = Shift->getOpcode();
1627 bool IsShl = ShiftOpcode == Instruction::Shl;
1628 const APInt *C3;
1629 if (match(Shift->getOperand(1), m_APInt(C3))) {
1630 APInt NewAndCst, NewCmpCst;
1631 bool AnyCmpCstBitsShiftedOut;
1632 if (ShiftOpcode == Instruction::Shl) {
1633 // For a left shift, we can fold if the comparison is not signed. We can
1634 // also fold a signed comparison if the mask value and comparison value
1635 // are not negative. These constraints may not be obvious, but we can
1636 // prove that they are correct using an SMT solver.
1637 if (Cmp.isSigned() && (C2.isNegative() || C1.isNegative()))
1638 return nullptr;
1639
1640 NewCmpCst = C1.lshr(*C3);
1641 NewAndCst = C2.lshr(*C3);
1642 AnyCmpCstBitsShiftedOut = NewCmpCst.shl(*C3) != C1;
1643 } else if (ShiftOpcode == Instruction::LShr) {
1644 // For a logical right shift, we can fold if the comparison is not signed.
1645 // We can also fold a signed comparison if the shifted mask value and the
1646 // shifted comparison value are not negative. These constraints may not be
1647 // obvious, but we can prove that they are correct using an SMT solver.
1648 NewCmpCst = C1.shl(*C3);
1649 NewAndCst = C2.shl(*C3);
1650 AnyCmpCstBitsShiftedOut = NewCmpCst.lshr(*C3) != C1;
1651 if (Cmp.isSigned() && (NewAndCst.isNegative() || NewCmpCst.isNegative()))
1652 return nullptr;
1653 } else {
1654 // For an arithmetic shift, check that both constants don't use (in a
1655 // signed sense) the top bits being shifted out.
1656 assert(ShiftOpcode == Instruction::AShr && "Unknown shift opcode")((ShiftOpcode == Instruction::AShr && "Unknown shift opcode"
) ? static_cast<void> (0) : __assert_fail ("ShiftOpcode == Instruction::AShr && \"Unknown shift opcode\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 1656, __PRETTY_FUNCTION__))
;
1657 NewCmpCst = C1.shl(*C3);
1658 NewAndCst = C2.shl(*C3);
1659 AnyCmpCstBitsShiftedOut = NewCmpCst.ashr(*C3) != C1;
1660 if (NewAndCst.ashr(*C3) != C2)
1661 return nullptr;
1662 }
1663
1664 if (AnyCmpCstBitsShiftedOut) {
1665 // If we shifted bits out, the fold is not going to work out. As a
1666 // special case, check to see if this means that the result is always
1667 // true or false now.
1668 if (Cmp.getPredicate() == ICmpInst::ICMP_EQ)
1669 return replaceInstUsesWith(Cmp, ConstantInt::getFalse(Cmp.getType()));
1670 if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
1671 return replaceInstUsesWith(Cmp, ConstantInt::getTrue(Cmp.getType()));
1672 } else {
1673 Value *NewAnd = Builder.CreateAnd(
1674 Shift->getOperand(0), ConstantInt::get(And->getType(), NewAndCst));
1675 return new ICmpInst(Cmp.getPredicate(),
1676 NewAnd, ConstantInt::get(And->getType(), NewCmpCst));
1677 }
1678 }
1679
1680 // Turn ((X >> Y) & C2) == 0 into (X & (C2 << Y)) == 0. The latter is
1681 // preferable because it allows the C2 << Y expression to be hoisted out of a
1682 // loop if Y is invariant and X is not.
1683 if (Shift->hasOneUse() && C1.isNullValue() && Cmp.isEquality() &&
1684 !Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) {
1685 // Compute C2 << Y.
1686 Value *NewShift =
1687 IsShl ? Builder.CreateLShr(And->getOperand(1), Shift->getOperand(1))
1688 : Builder.CreateShl(And->getOperand(1), Shift->getOperand(1));
1689
1690 // Compute X & (C2 << Y).
1691 Value *NewAnd = Builder.CreateAnd(Shift->getOperand(0), NewShift);
1692 return replaceOperand(Cmp, 0, NewAnd);
1693 }
1694
1695 return nullptr;
1696}
1697
1698/// Fold icmp (and X, C2), C1.
1699Instruction *InstCombinerImpl::foldICmpAndConstConst(ICmpInst &Cmp,
1700 BinaryOperator *And,
1701 const APInt &C1) {
1702 bool isICMP_NE = Cmp.getPredicate() == ICmpInst::ICMP_NE;
1703
1704 // For vectors: icmp ne (and X, 1), 0 --> trunc X to N x i1
1705 // TODO: We canonicalize to the longer form for scalars because we have
1706 // better analysis/folds for icmp, and codegen may be better with icmp.
1707 if (isICMP_NE && Cmp.getType()->isVectorTy() && C1.isNullValue() &&
1708 match(And->getOperand(1), m_One()))
1709 return new TruncInst(And->getOperand(0), Cmp.getType());
1710
1711 const APInt *C2;
1712 Value *X;
1713 if (!match(And, m_And(m_Value(X), m_APInt(C2))))
1714 return nullptr;
1715
1716 // Don't perform the following transforms if the AND has multiple uses
1717 if (!And->hasOneUse())
1718 return nullptr;
1719
1720 if (Cmp.isEquality() && C1.isNullValue()) {
1721 // Restrict this fold to single-use 'and' (PR10267).
1722 // Replace (and X, (1 << size(X)-1) != 0) with X s< 0
1723 if (C2->isSignMask()) {
1724 Constant *Zero = Constant::getNullValue(X->getType());
1725 auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
1726 return new ICmpInst(NewPred, X, Zero);
1727 }
1728
1729 // Restrict this fold only for single-use 'and' (PR10267).
1730 // ((%x & C) == 0) --> %x u< (-C) iff (-C) is power of two.
1731 if ((~(*C2) + 1).isPowerOf2()) {
1732 Constant *NegBOC =
1733 ConstantExpr::getNeg(cast<Constant>(And->getOperand(1)));
1734 auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
1735 return new ICmpInst(NewPred, X, NegBOC);
1736 }
1737 }
1738
1739 // If the LHS is an 'and' of a truncate and we can widen the and/compare to
1740 // the input width without changing the value produced, eliminate the cast:
1741 //
1742 // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1'
1743 //
1744 // We can do this transformation if the constants do not have their sign bits
1745 // set or if it is an equality comparison. Extending a relational comparison
1746 // when we're checking the sign bit would not work.
1747 Value *W;
1748 if (match(And->getOperand(0), m_OneUse(m_Trunc(m_Value(W)))) &&
1749 (Cmp.isEquality() || (!C1.isNegative() && !C2->isNegative()))) {
1750 // TODO: Is this a good transform for vectors? Wider types may reduce
1751 // throughput. Should this transform be limited (even for scalars) by using
1752 // shouldChangeType()?
1753 if (!Cmp.getType()->isVectorTy()) {
1754 Type *WideType = W->getType();
1755 unsigned WideScalarBits = WideType->getScalarSizeInBits();
1756 Constant *ZextC1 = ConstantInt::get(WideType, C1.zext(WideScalarBits));
1757 Constant *ZextC2 = ConstantInt::get(WideType, C2->zext(WideScalarBits));
1758 Value *NewAnd = Builder.CreateAnd(W, ZextC2, And->getName());
1759 return new ICmpInst(Cmp.getPredicate(), NewAnd, ZextC1);
1760 }
1761 }
1762
1763 if (Instruction *I = foldICmpAndShift(Cmp, And, C1, *C2))
1764 return I;
1765
1766 // (icmp pred (and (or (lshr A, B), A), 1), 0) -->
1767 // (icmp pred (and A, (or (shl 1, B), 1), 0))
1768 //
1769 // iff pred isn't signed
1770 if (!Cmp.isSigned() && C1.isNullValue() && And->getOperand(0)->hasOneUse() &&
1771 match(And->getOperand(1), m_One())) {
1772 Constant *One = cast<Constant>(And->getOperand(1));
1773 Value *Or = And->getOperand(0);
1774 Value *A, *B, *LShr;
1775 if (match(Or, m_Or(m_Value(LShr), m_Value(A))) &&
1776 match(LShr, m_LShr(m_Specific(A), m_Value(B)))) {
1777 unsigned UsesRemoved = 0;
1778 if (And->hasOneUse())
1779 ++UsesRemoved;
1780 if (Or->hasOneUse())
1781 ++UsesRemoved;
1782 if (LShr->hasOneUse())
1783 ++UsesRemoved;
1784
1785 // Compute A & ((1 << B) | 1)
1786 Value *NewOr = nullptr;
1787 if (auto *C = dyn_cast<Constant>(B)) {
1788 if (UsesRemoved >= 1)
1789 NewOr = ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One);
1790 } else {
1791 if (UsesRemoved >= 3)
1792 NewOr = Builder.CreateOr(Builder.CreateShl(One, B, LShr->getName(),
1793 /*HasNUW=*/true),
1794 One, Or->getName());
1795 }
1796 if (NewOr) {
1797 Value *NewAnd = Builder.CreateAnd(A, NewOr, And->getName());
1798 return replaceOperand(Cmp, 0, NewAnd);
1799 }
1800 }
1801 }
1802
1803 return nullptr;
1804}
1805
1806/// Fold icmp (and X, Y), C.
1807Instruction *InstCombinerImpl::foldICmpAndConstant(ICmpInst &Cmp,
1808 BinaryOperator *And,
1809 const APInt &C) {
1810 if (Instruction *I = foldICmpAndConstConst(Cmp, And, C))
1811 return I;
1812
1813 // TODO: These all require that Y is constant too, so refactor with the above.
1814
1815 // Try to optimize things like "A[i] & 42 == 0" to index computations.
1816 Value *X = And->getOperand(0);
1817 Value *Y = And->getOperand(1);
1818 if (auto *LI = dyn_cast<LoadInst>(X))
1819 if (auto *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
1820 if (auto *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
1821 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
1822 !LI->isVolatile() && isa<ConstantInt>(Y)) {
1823 ConstantInt *C2 = cast<ConstantInt>(Y);
1824 if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C2))
1825 return Res;
1826 }
1827
1828 if (!Cmp.isEquality())
1829 return nullptr;
1830
1831 // X & -C == -C -> X > u ~C
1832 // X & -C != -C -> X <= u ~C
1833 // iff C is a power of 2
1834 if (Cmp.getOperand(1) == Y && (-C).isPowerOf2()) {
1835 auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGT
1836 : CmpInst::ICMP_ULE;
1837 return new ICmpInst(NewPred, X, SubOne(cast<Constant>(Cmp.getOperand(1))));
1838 }
1839
1840 // (X & C2) == 0 -> (trunc X) >= 0
1841 // (X & C2) != 0 -> (trunc X) < 0
1842 // iff C2 is a power of 2 and it masks the sign bit of a legal integer type.
1843 const APInt *C2;
1844 if (And->hasOneUse() && C.isNullValue() && match(Y, m_APInt(C2))) {
1845 int32_t ExactLogBase2 = C2->exactLogBase2();
1846 if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) {
1847 Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1);
1848 if (auto *AndVTy = dyn_cast<VectorType>(And->getType()))
1849 NTy = VectorType::get(NTy, AndVTy->getElementCount());
1850 Value *Trunc = Builder.CreateTrunc(X, NTy);
1851 auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_SGE
1852 : CmpInst::ICMP_SLT;
1853 return new ICmpInst(NewPred, Trunc, Constant::getNullValue(NTy));
1854 }
1855 }
1856
1857 return nullptr;
1858}
1859
1860/// Fold icmp (or X, Y), C.
1861Instruction *InstCombinerImpl::foldICmpOrConstant(ICmpInst &Cmp,
1862 BinaryOperator *Or,
1863 const APInt &C) {
1864 ICmpInst::Predicate Pred = Cmp.getPredicate();
1865 if (C.isOneValue()) {
1866 // icmp slt signum(V) 1 --> icmp slt V, 1
1867 Value *V = nullptr;
1868 if (Pred == ICmpInst::ICMP_SLT && match(Or, m_Signum(m_Value(V))))
1869 return new ICmpInst(ICmpInst::ICMP_SLT, V,
1870 ConstantInt::get(V->getType(), 1));
1871 }
1872
1873 Value *OrOp0 = Or->getOperand(0), *OrOp1 = Or->getOperand(1);
1874 const APInt *MaskC;
1875 if (match(OrOp1, m_APInt(MaskC)) && Cmp.isEquality()) {
1876 if (*MaskC == C && (C + 1).isPowerOf2()) {
1877 // X | C == C --> X <=u C
1878 // X | C != C --> X >u C
1879 // iff C+1 is a power of 2 (C is a bitmask of the low bits)
1880 Pred = (Pred == CmpInst::ICMP_EQ) ? CmpInst::ICMP_ULE : CmpInst::ICMP_UGT;
1881 return new ICmpInst(Pred, OrOp0, OrOp1);
1882 }
1883
1884 // More general: canonicalize 'equality with set bits mask' to
1885 // 'equality with clear bits mask'.
1886 // (X | MaskC) == C --> (X & ~MaskC) == C ^ MaskC
1887 // (X | MaskC) != C --> (X & ~MaskC) != C ^ MaskC
1888 if (Or->hasOneUse()) {
1889 Value *And = Builder.CreateAnd(OrOp0, ~(*MaskC));
1890 Constant *NewC = ConstantInt::get(Or->getType(), C ^ (*MaskC));
1891 return new ICmpInst(Pred, And, NewC);
1892 }
1893 }
1894
1895 if (!Cmp.isEquality() || !C.isNullValue() || !Or->hasOneUse())
1896 return nullptr;
1897
1898 Value *P, *Q;
1899 if (match(Or, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
1900 // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
1901 // -> and (icmp eq P, null), (icmp eq Q, null).
1902 Value *CmpP =
1903 Builder.CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType()));
1904 Value *CmpQ =
1905 Builder.CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType()));
1906 auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
1907 return BinaryOperator::Create(BOpc, CmpP, CmpQ);
1908 }
1909
1910 // Are we using xors to bitwise check for a pair of (in)equalities? Convert to
1911 // a shorter form that has more potential to be folded even further.
1912 Value *X1, *X2, *X3, *X4;
1913 if (match(OrOp0, m_OneUse(m_Xor(m_Value(X1), m_Value(X2)))) &&
1914 match(OrOp1, m_OneUse(m_Xor(m_Value(X3), m_Value(X4))))) {
1915 // ((X1 ^ X2) || (X3 ^ X4)) == 0 --> (X1 == X2) && (X3 == X4)
1916 // ((X1 ^ X2) || (X3 ^ X4)) != 0 --> (X1 != X2) || (X3 != X4)
1917 Value *Cmp12 = Builder.CreateICmp(Pred, X1, X2);
1918 Value *Cmp34 = Builder.CreateICmp(Pred, X3, X4);
1919 auto BOpc = Pred == CmpInst::ICMP_EQ ? Instruction::And : Instruction::Or;
1920 return BinaryOperator::Create(BOpc, Cmp12, Cmp34);
1921 }
1922
1923 return nullptr;
1924}
1925
1926/// Fold icmp (mul X, Y), C.
1927Instruction *InstCombinerImpl::foldICmpMulConstant(ICmpInst &Cmp,
1928 BinaryOperator *Mul,
1929 const APInt &C) {
1930 const APInt *MulC;
1931 if (!match(Mul->getOperand(1), m_APInt(MulC)))
1932 return nullptr;
1933
1934 // If this is a test of the sign bit and the multiply is sign-preserving with
1935 // a constant operand, use the multiply LHS operand instead.
1936 ICmpInst::Predicate Pred = Cmp.getPredicate();
1937 if (isSignTest(Pred, C) && Mul->hasNoSignedWrap()) {
1938 if (MulC->isNegative())
1939 Pred = ICmpInst::getSwappedPredicate(Pred);
1940 return new ICmpInst(Pred, Mul->getOperand(0),
1941 Constant::getNullValue(Mul->getType()));
1942 }
1943
1944 // If the multiply does not wrap, try to divide the compare constant by the
1945 // multiplication factor.
1946 if (Cmp.isEquality() && !MulC->isNullValue()) {
1947 // (mul nsw X, MulC) == C --> X == C /s MulC
1948 if (Mul->hasNoSignedWrap() && C.srem(*MulC).isNullValue()) {
1949 Constant *NewC = ConstantInt::get(Mul->getType(), C.sdiv(*MulC));
1950 return new ICmpInst(Pred, Mul->getOperand(0), NewC);
1951 }
1952 // (mul nuw X, MulC) == C --> X == C /u MulC
1953 if (Mul->hasNoUnsignedWrap() && C.urem(*MulC).isNullValue()) {
1954 Constant *NewC = ConstantInt::get(Mul->getType(), C.udiv(*MulC));
1955 return new ICmpInst(Pred, Mul->getOperand(0), NewC);
1956 }
1957 }
1958
1959 return nullptr;
1960}
1961
1962/// Fold icmp (shl 1, Y), C.
1963static Instruction *foldICmpShlOne(ICmpInst &Cmp, Instruction *Shl,
1964 const APInt &C) {
1965 Value *Y;
1966 if (!match(Shl, m_Shl(m_One(), m_Value(Y))))
1967 return nullptr;
1968
1969 Type *ShiftType = Shl->getType();
1970 unsigned TypeBits = C.getBitWidth();
1971 bool CIsPowerOf2 = C.isPowerOf2();
1972 ICmpInst::Predicate Pred = Cmp.getPredicate();
1973 if (Cmp.isUnsigned()) {
1974 // (1 << Y) pred C -> Y pred Log2(C)
1975 if (!CIsPowerOf2) {
1976 // (1 << Y) < 30 -> Y <= 4
1977 // (1 << Y) <= 30 -> Y <= 4
1978 // (1 << Y) >= 30 -> Y > 4
1979 // (1 << Y) > 30 -> Y > 4
1980 if (Pred == ICmpInst::ICMP_ULT)
1981 Pred = ICmpInst::ICMP_ULE;
1982 else if (Pred == ICmpInst::ICMP_UGE)
1983 Pred = ICmpInst::ICMP_UGT;
1984 }
1985
1986 // (1 << Y) >= 2147483648 -> Y >= 31 -> Y == 31
1987 // (1 << Y) < 2147483648 -> Y < 31 -> Y != 31
1988 unsigned CLog2 = C.logBase2();
1989 if (CLog2 == TypeBits - 1) {
1990 if (Pred == ICmpInst::ICMP_UGE)
1991 Pred = ICmpInst::ICMP_EQ;
1992 else if (Pred == ICmpInst::ICMP_ULT)
1993 Pred = ICmpInst::ICMP_NE;
1994 }
1995 return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, CLog2));
1996 } else if (Cmp.isSigned()) {
1997 Constant *BitWidthMinusOne = ConstantInt::get(ShiftType, TypeBits - 1);
1998 if (C.isAllOnesValue()) {
1999 // (1 << Y) <= -1 -> Y == 31
2000 if (Pred == ICmpInst::ICMP_SLE)
2001 return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
2002
2003 // (1 << Y) > -1 -> Y != 31
2004 if (Pred == ICmpInst::ICMP_SGT)
2005 return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
2006 } else if (!C) {
2007 // (1 << Y) < 0 -> Y == 31
2008 // (1 << Y) <= 0 -> Y == 31
2009 if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
2010 return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne);
2011
2012 // (1 << Y) >= 0 -> Y != 31
2013 // (1 << Y) > 0 -> Y != 31
2014 if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
2015 return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne);
2016 }
2017 } else if (Cmp.isEquality() && CIsPowerOf2) {
2018 return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, C.logBase2()));
2019 }
2020
2021 return nullptr;
2022}
2023
2024/// Fold icmp (shl X, Y), C.
2025Instruction *InstCombinerImpl::foldICmpShlConstant(ICmpInst &Cmp,
2026 BinaryOperator *Shl,
2027 const APInt &C) {
2028 const APInt *ShiftVal;
2029 if (Cmp.isEquality() && match(Shl->getOperand(0), m_APInt(ShiftVal)))
2030 return foldICmpShlConstConst(Cmp, Shl->getOperand(1), C, *ShiftVal);
2031
2032 const APInt *ShiftAmt;
2033 if (!match(Shl->getOperand(1), m_APInt(ShiftAmt)))
2034 return foldICmpShlOne(Cmp, Shl, C);
2035
2036 // Check that the shift amount is in range. If not, don't perform undefined
2037 // shifts. When the shift is visited, it will be simplified.
2038 unsigned TypeBits = C.getBitWidth();
2039 if (ShiftAmt->uge(TypeBits))
2040 return nullptr;
2041
2042 ICmpInst::Predicate Pred = Cmp.getPredicate();
2043 Value *X = Shl->getOperand(0);
2044 Type *ShType = Shl->getType();
2045
2046 // NSW guarantees that we are only shifting out sign bits from the high bits,
2047 // so we can ASHR the compare constant without needing a mask and eliminate
2048 // the shift.
2049 if (Shl->hasNoSignedWrap()) {
2050 if (Pred == ICmpInst::ICMP_SGT) {
2051 // icmp Pred (shl nsw X, ShiftAmt), C --> icmp Pred X, (C >>s ShiftAmt)
2052 APInt ShiftedC = C.ashr(*ShiftAmt);
2053 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2054 }
2055 if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
2056 C.ashr(*ShiftAmt).shl(*ShiftAmt) == C) {
2057 APInt ShiftedC = C.ashr(*ShiftAmt);
2058 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2059 }
2060 if (Pred == ICmpInst::ICMP_SLT) {
2061 // SLE is the same as above, but SLE is canonicalized to SLT, so convert:
2062 // (X << S) <=s C is equiv to X <=s (C >> S) for all C
2063 // (X << S) <s (C + 1) is equiv to X <s (C >> S) + 1 if C <s SMAX
2064 // (X << S) <s C is equiv to X <s ((C - 1) >> S) + 1 if C >s SMIN
2065 assert(!C.isMinSignedValue() && "Unexpected icmp slt")((!C.isMinSignedValue() && "Unexpected icmp slt") ? static_cast
<void> (0) : __assert_fail ("!C.isMinSignedValue() && \"Unexpected icmp slt\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2065, __PRETTY_FUNCTION__))
;
2066 APInt ShiftedC = (C - 1).ashr(*ShiftAmt) + 1;
2067 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2068 }
2069 // If this is a signed comparison to 0 and the shift is sign preserving,
2070 // use the shift LHS operand instead; isSignTest may change 'Pred', so only
2071 // do that if we're sure to not continue on in this function.
2072 if (isSignTest(Pred, C))
2073 return new ICmpInst(Pred, X, Constant::getNullValue(ShType));
2074 }
2075
2076 // NUW guarantees that we are only shifting out zero bits from the high bits,
2077 // so we can LSHR the compare constant without needing a mask and eliminate
2078 // the shift.
2079 if (Shl->hasNoUnsignedWrap()) {
2080 if (Pred == ICmpInst::ICMP_UGT) {
2081 // icmp Pred (shl nuw X, ShiftAmt), C --> icmp Pred X, (C >>u ShiftAmt)
2082 APInt ShiftedC = C.lshr(*ShiftAmt);
2083 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2084 }
2085 if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
2086 C.lshr(*ShiftAmt).shl(*ShiftAmt) == C) {
2087 APInt ShiftedC = C.lshr(*ShiftAmt);
2088 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2089 }
2090 if (Pred == ICmpInst::ICMP_ULT) {
2091 // ULE is the same as above, but ULE is canonicalized to ULT, so convert:
2092 // (X << S) <=u C is equiv to X <=u (C >> S) for all C
2093 // (X << S) <u (C + 1) is equiv to X <u (C >> S) + 1 if C <u ~0u
2094 // (X << S) <u C is equiv to X <u ((C - 1) >> S) + 1 if C >u 0
2095 assert(C.ugt(0) && "ult 0 should have been eliminated")((C.ugt(0) && "ult 0 should have been eliminated") ? static_cast
<void> (0) : __assert_fail ("C.ugt(0) && \"ult 0 should have been eliminated\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2095, __PRETTY_FUNCTION__))
;
2096 APInt ShiftedC = (C - 1).lshr(*ShiftAmt) + 1;
2097 return new ICmpInst(Pred, X, ConstantInt::get(ShType, ShiftedC));
2098 }
2099 }
2100
2101 if (Cmp.isEquality() && Shl->hasOneUse()) {
2102 // Strength-reduce the shift into an 'and'.
2103 Constant *Mask = ConstantInt::get(
2104 ShType,
2105 APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt->getZExtValue()));
2106 Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask");
2107 Constant *LShrC = ConstantInt::get(ShType, C.lshr(*ShiftAmt));
2108 return new ICmpInst(Pred, And, LShrC);
2109 }
2110
2111 // Otherwise, if this is a comparison of the sign bit, simplify to and/test.
2112 bool TrueIfSigned = false;
2113 if (Shl->hasOneUse() && isSignBitCheck(Pred, C, TrueIfSigned)) {
2114 // (X << 31) <s 0 --> (X & 1) != 0
2115 Constant *Mask = ConstantInt::get(
2116 ShType,
2117 APInt::getOneBitSet(TypeBits, TypeBits - ShiftAmt->getZExtValue() - 1));
2118 Value *And = Builder.CreateAnd(X, Mask, Shl->getName() + ".mask");
2119 return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
2120 And, Constant::getNullValue(ShType));
2121 }
2122
2123 // Simplify 'shl' inequality test into 'and' equality test.
2124 if (Cmp.isUnsigned() && Shl->hasOneUse()) {
2125 // (X l<< C2) u<=/u> C1 iff C1+1 is power of two -> X & (~C1 l>> C2) ==/!= 0
2126 if ((C + 1).isPowerOf2() &&
2127 (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_UGT)) {
2128 Value *And = Builder.CreateAnd(X, (~C).lshr(ShiftAmt->getZExtValue()));
2129 return new ICmpInst(Pred == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_EQ
2130 : ICmpInst::ICMP_NE,
2131 And, Constant::getNullValue(ShType));
2132 }
2133 // (X l<< C2) u</u>= C1 iff C1 is power of two -> X & (-C1 l>> C2) ==/!= 0
2134 if (C.isPowerOf2() &&
2135 (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE)) {
2136 Value *And =
2137 Builder.CreateAnd(X, (~(C - 1)).lshr(ShiftAmt->getZExtValue()));
2138 return new ICmpInst(Pred == ICmpInst::ICMP_ULT ? ICmpInst::ICMP_EQ
2139 : ICmpInst::ICMP_NE,
2140 And, Constant::getNullValue(ShType));
2141 }
2142 }
2143
2144 // Transform (icmp pred iM (shl iM %v, N), C)
2145 // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N))
2146 // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N.
2147 // This enables us to get rid of the shift in favor of a trunc that may be
2148 // free on the target. It has the additional benefit of comparing to a
2149 // smaller constant that may be more target-friendly.
2150 unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1);
2151 if (Shl->hasOneUse() && Amt != 0 && C.countTrailingZeros() >= Amt &&
2152 DL.isLegalInteger(TypeBits - Amt)) {
2153 Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt);
2154 if (auto *ShVTy = dyn_cast<VectorType>(ShType))
2155 TruncTy = VectorType::get(TruncTy, ShVTy->getElementCount());
2156 Constant *NewC =
2157 ConstantInt::get(TruncTy, C.ashr(*ShiftAmt).trunc(TypeBits - Amt));
2158 return new ICmpInst(Pred, Builder.CreateTrunc(X, TruncTy), NewC);
2159 }
2160
2161 return nullptr;
2162}
2163
2164/// Fold icmp ({al}shr X, Y), C.
2165Instruction *InstCombinerImpl::foldICmpShrConstant(ICmpInst &Cmp,
2166 BinaryOperator *Shr,
2167 const APInt &C) {
2168 // An exact shr only shifts out zero bits, so:
2169 // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0
2170 Value *X = Shr->getOperand(0);
2171 CmpInst::Predicate Pred = Cmp.getPredicate();
2172 if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() &&
2173 C.isNullValue())
2174 return new ICmpInst(Pred, X, Cmp.getOperand(1));
2175
2176 const APInt *ShiftVal;
2177 if (Cmp.isEquality() && match(Shr->getOperand(0), m_APInt(ShiftVal)))
2178 return foldICmpShrConstConst(Cmp, Shr->getOperand(1), C, *ShiftVal);
2179
2180 const APInt *ShiftAmt;
2181 if (!match(Shr->getOperand(1), m_APInt(ShiftAmt)))
2182 return nullptr;
2183
2184 // Check that the shift amount is in range. If not, don't perform undefined
2185 // shifts. When the shift is visited it will be simplified.
2186 unsigned TypeBits = C.getBitWidth();
2187 unsigned ShAmtVal = ShiftAmt->getLimitedValue(TypeBits);
2188 if (ShAmtVal >= TypeBits || ShAmtVal == 0)
2189 return nullptr;
2190
2191 bool IsAShr = Shr->getOpcode() == Instruction::AShr;
2192 bool IsExact = Shr->isExact();
2193 Type *ShrTy = Shr->getType();
2194 // TODO: If we could guarantee that InstSimplify would handle all of the
2195 // constant-value-based preconditions in the folds below, then we could assert
2196 // those conditions rather than checking them. This is difficult because of
2197 // undef/poison (PR34838).
2198 if (IsAShr) {
2199 if (Pred == CmpInst::ICMP_SLT || (Pred == CmpInst::ICMP_SGT && IsExact)) {
2200 // icmp slt (ashr X, ShAmtC), C --> icmp slt X, (C << ShAmtC)
2201 // icmp sgt (ashr exact X, ShAmtC), C --> icmp sgt X, (C << ShAmtC)
2202 APInt ShiftedC = C.shl(ShAmtVal);
2203 if (ShiftedC.ashr(ShAmtVal) == C)
2204 return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
2205 }
2206 if (Pred == CmpInst::ICMP_SGT) {
2207 // icmp sgt (ashr X, ShAmtC), C --> icmp sgt X, ((C + 1) << ShAmtC) - 1
2208 APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1;
2209 if (!C.isMaxSignedValue() && !(C + 1).shl(ShAmtVal).isMinSignedValue() &&
2210 (ShiftedC + 1).ashr(ShAmtVal) == (C + 1))
2211 return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
2212 }
2213
2214 // If the compare constant has significant bits above the lowest sign-bit,
2215 // then convert an unsigned cmp to a test of the sign-bit:
2216 // (ashr X, ShiftC) u> C --> X s< 0
2217 // (ashr X, ShiftC) u< C --> X s> -1
2218 if (C.getBitWidth() > 2 && C.getNumSignBits() <= ShAmtVal) {
2219 if (Pred == CmpInst::ICMP_UGT) {
2220 return new ICmpInst(CmpInst::ICMP_SLT, X,
2221 ConstantInt::getNullValue(ShrTy));
2222 }
2223 if (Pred == CmpInst::ICMP_ULT) {
2224 return new ICmpInst(CmpInst::ICMP_SGT, X,
2225 ConstantInt::getAllOnesValue(ShrTy));
2226 }
2227 }
2228 } else {
2229 if (Pred == CmpInst::ICMP_ULT || (Pred == CmpInst::ICMP_UGT && IsExact)) {
2230 // icmp ult (lshr X, ShAmtC), C --> icmp ult X, (C << ShAmtC)
2231 // icmp ugt (lshr exact X, ShAmtC), C --> icmp ugt X, (C << ShAmtC)
2232 APInt ShiftedC = C.shl(ShAmtVal);
2233 if (ShiftedC.lshr(ShAmtVal) == C)
2234 return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
2235 }
2236 if (Pred == CmpInst::ICMP_UGT) {
2237 // icmp ugt (lshr X, ShAmtC), C --> icmp ugt X, ((C + 1) << ShAmtC) - 1
2238 APInt ShiftedC = (C + 1).shl(ShAmtVal) - 1;
2239 if ((ShiftedC + 1).lshr(ShAmtVal) == (C + 1))
2240 return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, ShiftedC));
2241 }
2242 }
2243
2244 if (!Cmp.isEquality())
2245 return nullptr;
2246
2247 // Handle equality comparisons of shift-by-constant.
2248
2249 // If the comparison constant changes with the shift, the comparison cannot
2250 // succeed (bits of the comparison constant cannot match the shifted value).
2251 // This should be known by InstSimplify and already be folded to true/false.
2252 assert(((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) ||((((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) ||
(!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) &&
"Expected icmp+shr simplify did not occur.") ? static_cast<
void> (0) : __assert_fail ("((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) || (!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) && \"Expected icmp+shr simplify did not occur.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2254, __PRETTY_FUNCTION__))
2253 (!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) &&((((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) ||
(!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) &&
"Expected icmp+shr simplify did not occur.") ? static_cast<
void> (0) : __assert_fail ("((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) || (!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) && \"Expected icmp+shr simplify did not occur.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2254, __PRETTY_FUNCTION__))
2254 "Expected icmp+shr simplify did not occur.")((((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) ||
(!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) &&
"Expected icmp+shr simplify did not occur.") ? static_cast<
void> (0) : __assert_fail ("((IsAShr && C.shl(ShAmtVal).ashr(ShAmtVal) == C) || (!IsAShr && C.shl(ShAmtVal).lshr(ShAmtVal) == C)) && \"Expected icmp+shr simplify did not occur.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2254, __PRETTY_FUNCTION__))
;
2255
2256 // If the bits shifted out are known zero, compare the unshifted value:
2257 // (X & 4) >> 1 == 2 --> (X & 4) == 4.
2258 if (Shr->isExact())
2259 return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, C << ShAmtVal));
2260
2261 if (Shr->hasOneUse()) {
2262 // Canonicalize the shift into an 'and':
2263 // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt)
2264 APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
2265 Constant *Mask = ConstantInt::get(ShrTy, Val);
2266 Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask");
2267 return new ICmpInst(Pred, And, ConstantInt::get(ShrTy, C << ShAmtVal));
2268 }
2269
2270 return nullptr;
2271}
2272
2273Instruction *InstCombinerImpl::foldICmpSRemConstant(ICmpInst &Cmp,
2274 BinaryOperator *SRem,
2275 const APInt &C) {
2276 // Match an 'is positive' or 'is negative' comparison of remainder by a
2277 // constant power-of-2 value:
2278 // (X % pow2C) sgt/slt 0
2279 const ICmpInst::Predicate Pred = Cmp.getPredicate();
2280 if (Pred != ICmpInst::ICMP_SGT && Pred != ICmpInst::ICMP_SLT)
2281 return nullptr;
2282
2283 // TODO: The one-use check is standard because we do not typically want to
2284 // create longer instruction sequences, but this might be a special-case
2285 // because srem is not good for analysis or codegen.
2286 if (!SRem->hasOneUse())
2287 return nullptr;
2288
2289 const APInt *DivisorC;
2290 if (!C.isNullValue() || !match(SRem->getOperand(1), m_Power2(DivisorC)))
2291 return nullptr;
2292
2293 // Mask off the sign bit and the modulo bits (low-bits).
2294 Type *Ty = SRem->getType();
2295 APInt SignMask = APInt::getSignMask(Ty->getScalarSizeInBits());
2296 Constant *MaskC = ConstantInt::get(Ty, SignMask | (*DivisorC - 1));
2297 Value *And = Builder.CreateAnd(SRem->getOperand(0), MaskC);
2298
2299 // For 'is positive?' check that the sign-bit is clear and at least 1 masked
2300 // bit is set. Example:
2301 // (i8 X % 32) s> 0 --> (X & 159) s> 0
2302 if (Pred == ICmpInst::ICMP_SGT)
2303 return new ICmpInst(ICmpInst::ICMP_SGT, And, ConstantInt::getNullValue(Ty));
2304
2305 // For 'is negative?' check that the sign-bit is set and at least 1 masked
2306 // bit is set. Example:
2307 // (i16 X % 4) s< 0 --> (X & 32771) u> 32768
2308 return new ICmpInst(ICmpInst::ICMP_UGT, And, ConstantInt::get(Ty, SignMask));
2309}
2310
2311/// Fold icmp (udiv X, Y), C.
2312Instruction *InstCombinerImpl::foldICmpUDivConstant(ICmpInst &Cmp,
2313 BinaryOperator *UDiv,
2314 const APInt &C) {
2315 const APInt *C2;
2316 if (!match(UDiv->getOperand(0), m_APInt(C2)))
2317 return nullptr;
2318
2319 assert(*C2 != 0 && "udiv 0, X should have been simplified already.")((*C2 != 0 && "udiv 0, X should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("*C2 != 0 && \"udiv 0, X should have been simplified already.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2319, __PRETTY_FUNCTION__))
;
2320
2321 // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1))
2322 Value *Y = UDiv->getOperand(1);
2323 if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) {
2324 assert(!C.isMaxValue() &&((!C.isMaxValue() && "icmp ugt X, UINT_MAX should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("!C.isMaxValue() && \"icmp ugt X, UINT_MAX should have been simplified already.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2325, __PRETTY_FUNCTION__))
2325 "icmp ugt X, UINT_MAX should have been simplified already.")((!C.isMaxValue() && "icmp ugt X, UINT_MAX should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("!C.isMaxValue() && \"icmp ugt X, UINT_MAX should have been simplified already.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2325, __PRETTY_FUNCTION__))
;
2326 return new ICmpInst(ICmpInst::ICMP_ULE, Y,
2327 ConstantInt::get(Y->getType(), C2->udiv(C + 1)));
2328 }
2329
2330 // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C)
2331 if (Cmp.getPredicate() == ICmpInst::ICMP_ULT) {
2332 assert(C != 0 && "icmp ult X, 0 should have been simplified already.")((C != 0 && "icmp ult X, 0 should have been simplified already."
) ? static_cast<void> (0) : __assert_fail ("C != 0 && \"icmp ult X, 0 should have been simplified already.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2332, __PRETTY_FUNCTION__))
;
2333 return new ICmpInst(ICmpInst::ICMP_UGT, Y,
2334 ConstantInt::get(Y->getType(), C2->udiv(C)));
2335 }
2336
2337 return nullptr;
2338}
2339
2340/// Fold icmp ({su}div X, Y), C.
2341Instruction *InstCombinerImpl::foldICmpDivConstant(ICmpInst &Cmp,
2342 BinaryOperator *Div,
2343 const APInt &C) {
2344 // Fold: icmp pred ([us]div X, C2), C -> range test
2345 // Fold this div into the comparison, producing a range check.
2346 // Determine, based on the divide type, what the range is being
2347 // checked. If there is an overflow on the low or high side, remember
2348 // it, otherwise compute the range [low, hi) bounding the new value.
2349 // See: InsertRangeTest above for the kinds of replacements possible.
2350 const APInt *C2;
2351 if (!match(Div->getOperand(1), m_APInt(C2)))
2352 return nullptr;
2353
2354 // FIXME: If the operand types don't match the type of the divide
2355 // then don't attempt this transform. The code below doesn't have the
2356 // logic to deal with a signed divide and an unsigned compare (and
2357 // vice versa). This is because (x /s C2) <s C produces different
2358 // results than (x /s C2) <u C or (x /u C2) <s C or even
2359 // (x /u C2) <u C. Simply casting the operands and result won't
2360 // work. :( The if statement below tests that condition and bails
2361 // if it finds it.
2362 bool DivIsSigned = Div->getOpcode() == Instruction::SDiv;
2363 if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned())
2364 return nullptr;
2365
2366 // The ProdOV computation fails on divide by 0 and divide by -1. Cases with
2367 // INT_MIN will also fail if the divisor is 1. Although folds of all these
2368 // division-by-constant cases should be present, we can not assert that they
2369 // have happened before we reach this icmp instruction.
2370 if (C2->isNullValue() || C2->isOneValue() ||
2371 (DivIsSigned && C2->isAllOnesValue()))
2372 return nullptr;
2373
2374 // Compute Prod = C * C2. We are essentially solving an equation of
2375 // form X / C2 = C. We solve for X by multiplying C2 and C.
2376 // By solving for X, we can turn this into a range check instead of computing
2377 // a divide.
2378 APInt Prod = C * *C2;
2379
2380 // Determine if the product overflows by seeing if the product is not equal to
2381 // the divide. Make sure we do the same kind of divide as in the LHS
2382 // instruction that we're folding.
2383 bool ProdOV = (DivIsSigned ? Prod.sdiv(*C2) : Prod.udiv(*C2)) != C;
2384
2385 ICmpInst::Predicate Pred = Cmp.getPredicate();
2386
2387 // If the division is known to be exact, then there is no remainder from the
2388 // divide, so the covered range size is unit, otherwise it is the divisor.
2389 APInt RangeSize = Div->isExact() ? APInt(C2->getBitWidth(), 1) : *C2;
2390
2391 // Figure out the interval that is being checked. For example, a comparison
2392 // like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
2393 // Compute this interval based on the constants involved and the signedness of
2394 // the compare/divide. This computes a half-open interval, keeping track of
2395 // whether either value in the interval overflows. After analysis each
2396 // overflow variable is set to 0 if it's corresponding bound variable is valid
2397 // -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
2398 int LoOverflow = 0, HiOverflow = 0;
2399 APInt LoBound, HiBound;
2400
2401 if (!DivIsSigned) { // udiv
2402 // e.g. X/5 op 3 --> [15, 20)
2403 LoBound = Prod;
2404 HiOverflow = LoOverflow = ProdOV;
2405 if (!HiOverflow) {
2406 // If this is not an exact divide, then many values in the range collapse
2407 // to the same result value.
2408 HiOverflow = addWithOverflow(HiBound, LoBound, RangeSize, false);
2409 }
2410 } else if (C2->isStrictlyPositive()) { // Divisor is > 0.
2411 if (C.isNullValue()) { // (X / pos) op 0
2412 // Can't overflow. e.g. X/2 op 0 --> [-1, 2)
2413 LoBound = -(RangeSize - 1);
2414 HiBound = RangeSize;
2415 } else if (C.isStrictlyPositive()) { // (X / pos) op pos
2416 LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
2417 HiOverflow = LoOverflow = ProdOV;
2418 if (!HiOverflow)
2419 HiOverflow = addWithOverflow(HiBound, Prod, RangeSize, true);
2420 } else { // (X / pos) op neg
2421 // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
2422 HiBound = Prod + 1;
2423 LoOverflow = HiOverflow = ProdOV ? -1 : 0;
2424 if (!LoOverflow) {
2425 APInt DivNeg = -RangeSize;
2426 LoOverflow = addWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
2427 }
2428 }
2429 } else if (C2->isNegative()) { // Divisor is < 0.
2430 if (Div->isExact())
2431 RangeSize.negate();
2432 if (C.isNullValue()) { // (X / neg) op 0
2433 // e.g. X/-5 op 0 --> [-4, 5)
2434 LoBound = RangeSize + 1;
2435 HiBound = -RangeSize;
2436 if (HiBound == *C2) { // -INTMIN = INTMIN
2437 HiOverflow = 1; // [INTMIN+1, overflow)
2438 HiBound = APInt(); // e.g. X/INTMIN = 0 --> X > INTMIN
2439 }
2440 } else if (C.isStrictlyPositive()) { // (X / neg) op pos
2441 // e.g. X/-5 op 3 --> [-19, -14)
2442 HiBound = Prod + 1;
2443 HiOverflow = LoOverflow = ProdOV ? -1 : 0;
2444 if (!LoOverflow)
2445 LoOverflow = addWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
2446 } else { // (X / neg) op neg
2447 LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
2448 LoOverflow = HiOverflow = ProdOV;
2449 if (!HiOverflow)
2450 HiOverflow = subWithOverflow(HiBound, Prod, RangeSize, true);
2451 }
2452
2453 // Dividing by a negative swaps the condition. LT <-> GT
2454 Pred = ICmpInst::getSwappedPredicate(Pred);
2455 }
2456
2457 Value *X = Div->getOperand(0);
2458 switch (Pred) {
2459 default: llvm_unreachable("Unhandled icmp opcode!")::llvm::llvm_unreachable_internal("Unhandled icmp opcode!", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2459)
;
2460 case ICmpInst::ICMP_EQ:
2461 if (LoOverflow && HiOverflow)
2462 return replaceInstUsesWith(Cmp, Builder.getFalse());
2463 if (HiOverflow)
2464 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
2465 ICmpInst::ICMP_UGE, X,
2466 ConstantInt::get(Div->getType(), LoBound));
2467 if (LoOverflow)
2468 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
2469 ICmpInst::ICMP_ULT, X,
2470 ConstantInt::get(Div->getType(), HiBound));
2471 return replaceInstUsesWith(
2472 Cmp, insertRangeTest(X, LoBound, HiBound, DivIsSigned, true));
2473 case ICmpInst::ICMP_NE:
2474 if (LoOverflow && HiOverflow)
2475 return replaceInstUsesWith(Cmp, Builder.getTrue());
2476 if (HiOverflow)
2477 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
2478 ICmpInst::ICMP_ULT, X,
2479 ConstantInt::get(Div->getType(), LoBound));
2480 if (LoOverflow)
2481 return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
2482 ICmpInst::ICMP_UGE, X,
2483 ConstantInt::get(Div->getType(), HiBound));
2484 return replaceInstUsesWith(Cmp,
2485 insertRangeTest(X, LoBound, HiBound,
2486 DivIsSigned, false));
2487 case ICmpInst::ICMP_ULT:
2488 case ICmpInst::ICMP_SLT:
2489 if (LoOverflow == +1) // Low bound is greater than input range.
2490 return replaceInstUsesWith(Cmp, Builder.getTrue());
2491 if (LoOverflow == -1) // Low bound is less than input range.
2492 return replaceInstUsesWith(Cmp, Builder.getFalse());
2493 return new ICmpInst(Pred, X, ConstantInt::get(Div->getType(), LoBound));
2494 case ICmpInst::ICMP_UGT:
2495 case ICmpInst::ICMP_SGT:
2496 if (HiOverflow == +1) // High bound greater than input range.
2497 return replaceInstUsesWith(Cmp, Builder.getFalse());
2498 if (HiOverflow == -1) // High bound less than input range.
2499 return replaceInstUsesWith(Cmp, Builder.getTrue());
2500 if (Pred == ICmpInst::ICMP_UGT)
2501 return new ICmpInst(ICmpInst::ICMP_UGE, X,
2502 ConstantInt::get(Div->getType(), HiBound));
2503 return new ICmpInst(ICmpInst::ICMP_SGE, X,
2504 ConstantInt::get(Div->getType(), HiBound));
2505 }
2506
2507 return nullptr;
2508}
2509
2510/// Fold icmp (sub X, Y), C.
2511Instruction *InstCombinerImpl::foldICmpSubConstant(ICmpInst &Cmp,
2512 BinaryOperator *Sub,
2513 const APInt &C) {
2514 Value *X = Sub->getOperand(0), *Y = Sub->getOperand(1);
2515 ICmpInst::Predicate Pred = Cmp.getPredicate();
2516 const APInt *C2;
2517 APInt SubResult;
2518
2519 // icmp eq/ne (sub C, Y), C -> icmp eq/ne Y, 0
2520 if (match(X, m_APInt(C2)) && *C2 == C && Cmp.isEquality())
2521 return new ICmpInst(Cmp.getPredicate(), Y,
2522 ConstantInt::get(Y->getType(), 0));
2523
2524 // (icmp P (sub nuw|nsw C2, Y), C) -> (icmp swap(P) Y, C2-C)
2525 if (match(X, m_APInt(C2)) &&
2526 ((Cmp.isUnsigned() && Sub->hasNoUnsignedWrap()) ||
2527 (Cmp.isSigned() && Sub->hasNoSignedWrap())) &&
2528 !subWithOverflow(SubResult, *C2, C, Cmp.isSigned()))
2529 return new ICmpInst(Cmp.getSwappedPredicate(), Y,
2530 ConstantInt::get(Y->getType(), SubResult));
2531
2532 // The following transforms are only worth it if the only user of the subtract
2533 // is the icmp.
2534 if (!Sub->hasOneUse())
2535 return nullptr;
2536
2537 if (Sub->hasNoSignedWrap()) {
2538 // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y)
2539 if (Pred == ICmpInst::ICMP_SGT && C.isAllOnesValue())
2540 return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
2541
2542 // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y)
2543 if (Pred == ICmpInst::ICMP_SGT && C.isNullValue())
2544 return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
2545
2546 // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y)
2547 if (Pred == ICmpInst::ICMP_SLT && C.isNullValue())
2548 return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
2549
2550 // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y)
2551 if (Pred == ICmpInst::ICMP_SLT && C.isOneValue())
2552 return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
2553 }
2554
2555 if (!match(X, m_APInt(C2)))
2556 return nullptr;
2557
2558 // C2 - Y <u C -> (Y | (C - 1)) == C2
2559 // iff (C2 & (C - 1)) == C - 1 and C is a power of 2
2560 if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() &&
2561 (*C2 & (C - 1)) == (C - 1))
2562 return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateOr(Y, C - 1), X);
2563
2564 // C2 - Y >u C -> (Y | C) != C2
2565 // iff C2 & C == C and C + 1 is a power of 2
2566 if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == C)
2567 return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateOr(Y, C), X);
2568
2569 return nullptr;
2570}
2571
2572/// Fold icmp (add X, Y), C.
2573Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
2574 BinaryOperator *Add,
2575 const APInt &C) {
2576 Value *Y = Add->getOperand(1);
2577 const APInt *C2;
2578 if (Cmp.isEquality() || !match(Y, m_APInt(C2)))
2579 return nullptr;
2580
2581 // Fold icmp pred (add X, C2), C.
2582 Value *X = Add->getOperand(0);
2583 Type *Ty = Add->getType();
2584 CmpInst::Predicate Pred = Cmp.getPredicate();
2585
2586 // If the add does not wrap, we can always adjust the compare by subtracting
2587 // the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
2588 // are canonicalized to SGT/SLT/UGT/ULT.
2589 if ((Add->hasNoSignedWrap() &&
2590 (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) ||
2591 (Add->hasNoUnsignedWrap() &&
2592 (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) {
2593 bool Overflow;
2594 APInt NewC =
2595 Cmp.isSigned() ? C.ssub_ov(*C2, Overflow) : C.usub_ov(*C2, Overflow);
2596 // If there is overflow, the result must be true or false.
2597 // TODO: Can we assert there is no overflow because InstSimplify always
2598 // handles those cases?
2599 if (!Overflow)
2600 // icmp Pred (add nsw X, C2), C --> icmp Pred X, (C - C2)
2601 return new ICmpInst(Pred, X, ConstantInt::get(Ty, NewC));
2602 }
2603
2604 auto CR = ConstantRange::makeExactICmpRegion(Pred, C).subtract(*C2);
2605 const APInt &Upper = CR.getUpper();
2606 const APInt &Lower = CR.getLower();
2607 if (Cmp.isSigned()) {
2608 if (Lower.isSignMask())
2609 return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, Upper));
2610 if (Upper.isSignMask())
2611 return new ICmpInst(ICmpInst::ICMP_SGE, X, ConstantInt::get(Ty, Lower));
2612 } else {
2613 if (Lower.isMinValue())
2614 return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, Upper));
2615 if (Upper.isMinValue())
2616 return new ICmpInst(ICmpInst::ICMP_UGE, X, ConstantInt::get(Ty, Lower));
2617 }
2618
2619 if (!Add->hasOneUse())
2620 return nullptr;
2621
2622 // X+C <u C2 -> (X & -C2) == C
2623 // iff C & (C2-1) == 0
2624 // C2 is a power of 2
2625 if (Pred == ICmpInst::ICMP_ULT && C.isPowerOf2() && (*C2 & (C - 1)) == 0)
2626 return new ICmpInst(ICmpInst::ICMP_EQ, Builder.CreateAnd(X, -C),
2627 ConstantExpr::getNeg(cast<Constant>(Y)));
2628
2629 // X+C >u C2 -> (X & ~C2) != C
2630 // iff C & C2 == 0
2631 // C2+1 is a power of 2
2632 if (Pred == ICmpInst::ICMP_UGT && (C + 1).isPowerOf2() && (*C2 & C) == 0)
2633 return new ICmpInst(ICmpInst::ICMP_NE, Builder.CreateAnd(X, ~C),
2634 ConstantExpr::getNeg(cast<Constant>(Y)));
2635
2636 return nullptr;
2637}
2638
2639bool InstCombinerImpl::matchThreeWayIntCompare(SelectInst *SI, Value *&LHS,
2640 Value *&RHS, ConstantInt *&Less,
2641 ConstantInt *&Equal,
2642 ConstantInt *&Greater) {
2643 // TODO: Generalize this to work with other comparison idioms or ensure
2644 // they get canonicalized into this form.
2645
2646 // select i1 (a == b),
2647 // i32 Equal,
2648 // i32 (select i1 (a < b), i32 Less, i32 Greater)
2649 // where Equal, Less and Greater are placeholders for any three constants.
2650 ICmpInst::Predicate PredA;
2651 if (!match(SI->getCondition(), m_ICmp(PredA, m_Value(LHS), m_Value(RHS))) ||
2652 !ICmpInst::isEquality(PredA))
2653 return false;
2654 Value *EqualVal = SI->getTrueValue();
2655 Value *UnequalVal = SI->getFalseValue();
2656 // We still can get non-canonical predicate here, so canonicalize.
2657 if (PredA == ICmpInst::ICMP_NE)
2658 std::swap(EqualVal, UnequalVal);
2659 if (!match(EqualVal, m_ConstantInt(Equal)))
2660 return false;
2661 ICmpInst::Predicate PredB;
2662 Value *LHS2, *RHS2;
2663 if (!match(UnequalVal, m_Select(m_ICmp(PredB, m_Value(LHS2), m_Value(RHS2)),
2664 m_ConstantInt(Less), m_ConstantInt(Greater))))
2665 return false;
2666 // We can get predicate mismatch here, so canonicalize if possible:
2667 // First, ensure that 'LHS' match.
2668 if (LHS2 != LHS) {
2669 // x sgt y <--> y slt x
2670 std::swap(LHS2, RHS2);
2671 PredB = ICmpInst::getSwappedPredicate(PredB);
2672 }
2673 if (LHS2 != LHS)
2674 return false;
2675 // We also need to canonicalize 'RHS'.
2676 if (PredB == ICmpInst::ICMP_SGT && isa<Constant>(RHS2)) {
2677 // x sgt C-1 <--> x sge C <--> not(x slt C)
2678 auto FlippedStrictness =
2679 InstCombiner::getFlippedStrictnessPredicateAndConstant(
2680 PredB, cast<Constant>(RHS2));
2681 if (!FlippedStrictness)
2682 return false;
2683 assert(FlippedStrictness->first == ICmpInst::ICMP_SGE && "Sanity check")((FlippedStrictness->first == ICmpInst::ICMP_SGE &&
"Sanity check") ? static_cast<void> (0) : __assert_fail
("FlippedStrictness->first == ICmpInst::ICMP_SGE && \"Sanity check\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2683, __PRETTY_FUNCTION__))
;
2684 RHS2 = FlippedStrictness->second;
2685 // And kind-of perform the result swap.
2686 std::swap(Less, Greater);
2687 PredB = ICmpInst::ICMP_SLT;
2688 }
2689 return PredB == ICmpInst::ICMP_SLT && RHS == RHS2;
2690}
2691
2692Instruction *InstCombinerImpl::foldICmpSelectConstant(ICmpInst &Cmp,
2693 SelectInst *Select,
2694 ConstantInt *C) {
2695
2696 assert(C && "Cmp RHS should be a constant int!")((C && "Cmp RHS should be a constant int!") ? static_cast
<void> (0) : __assert_fail ("C && \"Cmp RHS should be a constant int!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2696, __PRETTY_FUNCTION__))
;
2697 // If we're testing a constant value against the result of a three way
2698 // comparison, the result can be expressed directly in terms of the
2699 // original values being compared. Note: We could possibly be more
2700 // aggressive here and remove the hasOneUse test. The original select is
2701 // really likely to simplify or sink when we remove a test of the result.
2702 Value *OrigLHS, *OrigRHS;
2703 ConstantInt *C1LessThan, *C2Equal, *C3GreaterThan;
2704 if (Cmp.hasOneUse() &&
2705 matchThreeWayIntCompare(Select, OrigLHS, OrigRHS, C1LessThan, C2Equal,
2706 C3GreaterThan)) {
2707 assert(C1LessThan && C2Equal && C3GreaterThan)((C1LessThan && C2Equal && C3GreaterThan) ? static_cast
<void> (0) : __assert_fail ("C1LessThan && C2Equal && C3GreaterThan"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 2707, __PRETTY_FUNCTION__))
;
2708
2709 bool TrueWhenLessThan =
2710 ConstantExpr::getCompare(Cmp.getPredicate(), C1LessThan, C)
2711 ->isAllOnesValue();
2712 bool TrueWhenEqual =
2713 ConstantExpr::getCompare(Cmp.getPredicate(), C2Equal, C)
2714 ->isAllOnesValue();
2715 bool TrueWhenGreaterThan =
2716 ConstantExpr::getCompare(Cmp.getPredicate(), C3GreaterThan, C)
2717 ->isAllOnesValue();
2718
2719 // This generates the new instruction that will replace the original Cmp
2720 // Instruction. Instead of enumerating the various combinations when
2721 // TrueWhenLessThan, TrueWhenEqual and TrueWhenGreaterThan are true versus
2722 // false, we rely on chaining of ORs and future passes of InstCombine to
2723 // simplify the OR further (i.e. a s< b || a == b becomes a s<= b).
2724
2725 // When none of the three constants satisfy the predicate for the RHS (C),
2726 // the entire original Cmp can be simplified to a false.
2727 Value *Cond = Builder.getFalse();
2728 if (TrueWhenLessThan)
2729 Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SLT,
2730 OrigLHS, OrigRHS));
2731 if (TrueWhenEqual)
2732 Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_EQ,
2733 OrigLHS, OrigRHS));
2734 if (TrueWhenGreaterThan)
2735 Cond = Builder.CreateOr(Cond, Builder.CreateICmp(ICmpInst::ICMP_SGT,
2736 OrigLHS, OrigRHS));
2737
2738 return replaceInstUsesWith(Cmp, Cond);
2739 }
2740 return nullptr;
2741}
2742
2743static Instruction *foldICmpBitCast(ICmpInst &Cmp,
2744 InstCombiner::BuilderTy &Builder) {
2745 auto *Bitcast = dyn_cast<BitCastInst>(Cmp.getOperand(0));
2746 if (!Bitcast)
2747 return nullptr;
2748
2749 ICmpInst::Predicate Pred = Cmp.getPredicate();
2750 Value *Op1 = Cmp.getOperand(1);
2751 Value *BCSrcOp = Bitcast->getOperand(0);
2752
2753 // Make sure the bitcast doesn't change the number of vector elements.
2754 if (Bitcast->getSrcTy()->getScalarSizeInBits() ==
2755 Bitcast->getDestTy()->getScalarSizeInBits()) {
2756 // Zero-equality and sign-bit checks are preserved through sitofp + bitcast.
2757 Value *X;
2758 if (match(BCSrcOp, m_SIToFP(m_Value(X)))) {
2759 // icmp eq (bitcast (sitofp X)), 0 --> icmp eq X, 0
2760 // icmp ne (bitcast (sitofp X)), 0 --> icmp ne X, 0
2761 // icmp slt (bitcast (sitofp X)), 0 --> icmp slt X, 0
2762 // icmp sgt (bitcast (sitofp X)), 0 --> icmp sgt X, 0
2763 if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_SLT ||
2764 Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT) &&
2765 match(Op1, m_Zero()))
2766 return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
2767
2768 // icmp slt (bitcast (sitofp X)), 1 --> icmp slt X, 1
2769 if (Pred == ICmpInst::ICMP_SLT && match(Op1, m_One()))
2770 return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), 1));
2771
2772 // icmp sgt (bitcast (sitofp X)), -1 --> icmp sgt X, -1
2773 if (Pred == ICmpInst::ICMP_SGT && match(Op1, m_AllOnes()))
2774 return new ICmpInst(Pred, X,
2775 ConstantInt::getAllOnesValue(X->getType()));
2776 }
2777
2778 // Zero-equality checks are preserved through unsigned floating-point casts:
2779 // icmp eq (bitcast (uitofp X)), 0 --> icmp eq X, 0
2780 // icmp ne (bitcast (uitofp X)), 0 --> icmp ne X, 0
2781 if (match(BCSrcOp, m_UIToFP(m_Value(X))))
2782 if (Cmp.isEquality() && match(Op1, m_Zero()))
2783 return new ICmpInst(Pred, X, ConstantInt::getNullValue(X->getType()));
2784
2785 // If this is a sign-bit test of a bitcast of a casted FP value, eliminate
2786 // the FP extend/truncate because that cast does not change the sign-bit.
2787 // This is true for all standard IEEE-754 types and the X86 80-bit type.
2788 // The sign-bit is always the most significant bit in those types.
2789 const APInt *C;
2790 bool TrueIfSigned;
2791 if (match(Op1, m_APInt(C)) && Bitcast->hasOneUse() &&
2792 InstCombiner::isSignBitCheck(Pred, *C, TrueIfSigned)) {
2793 if (match(BCSrcOp, m_FPExt(m_Value(X))) ||
2794 match(BCSrcOp, m_FPTrunc(m_Value(X)))) {
2795 // (bitcast (fpext/fptrunc X)) to iX) < 0 --> (bitcast X to iY) < 0
2796 // (bitcast (fpext/fptrunc X)) to iX) > -1 --> (bitcast X to iY) > -1
2797 Type *XType = X->getType();
2798
2799 // We can't currently handle Power style floating point operations here.
2800 if (!(XType->isPPC_FP128Ty() || BCSrcOp->getType()->isPPC_FP128Ty())) {
2801
2802 Type *NewType = Builder.getIntNTy(XType->getScalarSizeInBits());
2803 if (auto *XVTy = dyn_cast<VectorType>(XType))
2804 NewType = VectorType::get(NewType, XVTy->getElementCount());
2805 Value *NewBitcast = Builder.CreateBitCast(X, NewType);
2806 if (TrueIfSigned)
2807 return new ICmpInst(ICmpInst::ICMP_SLT, NewBitcast,
2808 ConstantInt::getNullValue(NewType));
2809 else
2810 return new ICmpInst(ICmpInst::ICMP_SGT, NewBitcast,
2811 ConstantInt::getAllOnesValue(NewType));
2812 }
2813 }
2814 }
2815 }
2816
2817 // Test to see if the operands of the icmp are casted versions of other
2818 // values. If the ptr->ptr cast can be stripped off both arguments, do so.
2819 if (Bitcast->getType()->isPointerTy() &&
2820 (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
2821 // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
2822 // so eliminate it as well.
2823 if (auto *BC2 = dyn_cast<BitCastInst>(Op1))
2824 Op1 = BC2->getOperand(0);
2825
2826 Op1 = Builder.CreateBitCast(Op1, BCSrcOp->getType());
2827 return new ICmpInst(Pred, BCSrcOp, Op1);
2828 }
2829
2830 // Folding: icmp <pred> iN X, C
2831 // where X = bitcast <M x iK> (shufflevector <M x iK> %vec, undef, SC)) to iN
2832 // and C is a splat of a K-bit pattern
2833 // and SC is a constant vector = <C', C', C', ..., C'>
2834 // Into:
2835 // %E = extractelement <M x iK> %vec, i32 C'
2836 // icmp <pred> iK %E, trunc(C)
2837 const APInt *C;
2838 if (!match(Cmp.getOperand(1), m_APInt(C)) ||
2839 !Bitcast->getType()->isIntegerTy() ||
2840 !Bitcast->getSrcTy()->isIntOrIntVectorTy())
2841 return nullptr;
2842
2843 Value *Vec;
2844 ArrayRef<int> Mask;
2845 if (match(BCSrcOp, m_Shuffle(m_Value(Vec), m_Undef(), m_Mask(Mask)))) {
2846 // Check whether every element of Mask is the same constant
2847 if (is_splat(Mask)) {
2848 auto *VecTy = cast<VectorType>(BCSrcOp->getType());
2849 auto *EltTy = cast<IntegerType>(VecTy->getElementType());
2850 if (C->isSplat(EltTy->getBitWidth())) {
2851 // Fold the icmp based on the value of C
2852 // If C is M copies of an iK sized bit pattern,
2853 // then:
2854 // => %E = extractelement <N x iK> %vec, i32 Elem
2855 // icmp <pred> iK %SplatVal, <pattern>
2856 Value *Elem = Builder.getInt32(Mask[0]);
2857 Value *Extract = Builder.CreateExtractElement(Vec, Elem);
2858 Value *NewC = ConstantInt::get(EltTy, C->trunc(EltTy->getBitWidth()));
2859 return new ICmpInst(Pred, Extract, NewC);
2860 }
2861 }
2862 }
2863 return nullptr;
2864}
2865
2866/// Try to fold integer comparisons with a constant operand: icmp Pred X, C
2867/// where X is some kind of instruction.
2868Instruction *InstCombinerImpl::foldICmpInstWithConstant(ICmpInst &Cmp) {
2869 const APInt *C;
2870 if (!match(Cmp.getOperand(1), m_APInt(C)))
2871 return nullptr;
2872
2873 if (auto *BO = dyn_cast<BinaryOperator>(Cmp.getOperand(0))) {
2874 switch (BO->getOpcode()) {
2875 case Instruction::Xor:
2876 if (Instruction *I = foldICmpXorConstant(Cmp, BO, *C))
2877 return I;
2878 break;
2879 case Instruction::And:
2880 if (Instruction *I = foldICmpAndConstant(Cmp, BO, *C))
2881 return I;
2882 break;
2883 case Instruction::Or:
2884 if (Instruction *I = foldICmpOrConstant(Cmp, BO, *C))
2885 return I;
2886 break;
2887 case Instruction::Mul:
2888 if (Instruction *I = foldICmpMulConstant(Cmp, BO, *C))
2889 return I;
2890 break;
2891 case Instruction::Shl:
2892 if (Instruction *I = foldICmpShlConstant(Cmp, BO, *C))
2893 return I;
2894 break;
2895 case Instruction::LShr:
2896 case Instruction::AShr:
2897 if (Instruction *I = foldICmpShrConstant(Cmp, BO, *C))
2898 return I;
2899 break;
2900 case Instruction::SRem:
2901 if (Instruction *I = foldICmpSRemConstant(Cmp, BO, *C))
2902 return I;
2903 break;
2904 case Instruction::UDiv:
2905 if (Instruction *I = foldICmpUDivConstant(Cmp, BO, *C))
2906 return I;
2907 LLVM_FALLTHROUGH[[gnu::fallthrough]];
2908 case Instruction::SDiv:
2909 if (Instruction *I = foldICmpDivConstant(Cmp, BO, *C))
2910 return I;
2911 break;
2912 case Instruction::Sub:
2913 if (Instruction *I = foldICmpSubConstant(Cmp, BO, *C))
2914 return I;
2915 break;
2916 case Instruction::Add:
2917 if (Instruction *I = foldICmpAddConstant(Cmp, BO, *C))
2918 return I;
2919 break;
2920 default:
2921 break;
2922 }
2923 // TODO: These folds could be refactored to be part of the above calls.
2924 if (Instruction *I = foldICmpBinOpEqualityWithConstant(Cmp, BO, *C))
2925 return I;
2926 }
2927
2928 // Match against CmpInst LHS being instructions other than binary operators.
2929
2930 if (auto *SI = dyn_cast<SelectInst>(Cmp.getOperand(0))) {
2931 // For now, we only support constant integers while folding the
2932 // ICMP(SELECT)) pattern. We can extend this to support vector of integers
2933 // similar to the cases handled by binary ops above.
2934 if (ConstantInt *ConstRHS = dyn_cast<ConstantInt>(Cmp.getOperand(1)))
2935 if (Instruction *I = foldICmpSelectConstant(Cmp, SI, ConstRHS))
2936 return I;
2937 }
2938
2939 if (auto *TI = dyn_cast<TruncInst>(Cmp.getOperand(0))) {
2940 if (Instruction *I = foldICmpTruncConstant(Cmp, TI, *C))
2941 return I;
2942 }
2943
2944 if (auto *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0)))
2945 if (Instruction *I = foldICmpIntrinsicWithConstant(Cmp, II, *C))
2946 return I;
2947
2948 return nullptr;
2949}
2950
2951/// Fold an icmp equality instruction with binary operator LHS and constant RHS:
2952/// icmp eq/ne BO, C.
2953Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
2954 ICmpInst &Cmp, BinaryOperator *BO, const APInt &C) {
2955 // TODO: Some of these folds could work with arbitrary constants, but this
2956 // function is limited to scalar and vector splat constants.
2957 if (!Cmp.isEquality())
2958 return nullptr;
2959
2960 ICmpInst::Predicate Pred = Cmp.getPredicate();
2961 bool isICMP_NE = Pred == ICmpInst::ICMP_NE;
2962 Constant *RHS = cast<Constant>(Cmp.getOperand(1));
2963 Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
2964
2965 switch (BO->getOpcode()) {
2966 case Instruction::SRem:
2967 // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
2968 if (C.isNullValue() && BO->hasOneUse()) {
2969 const APInt *BOC;
2970 if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) {
2971 Value *NewRem = Builder.CreateURem(BOp0, BOp1, BO->getName());
2972 return new ICmpInst(Pred, NewRem,
2973 Constant::getNullValue(BO->getType()));
2974 }
2975 }
2976 break;
2977 case Instruction::Add: {
2978 // Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
2979 if (Constant *BOC = dyn_cast<Constant>(BOp1)) {
2980 if (BO->hasOneUse())
2981 return new ICmpInst(Pred, BOp0, ConstantExpr::getSub(RHS, BOC));
2982 } else if (C.isNullValue()) {
2983 // Replace ((add A, B) != 0) with (A != -B) if A or B is
2984 // efficiently invertible, or if the add has just this one use.
2985 if (Value *NegVal = dyn_castNegVal(BOp1))
2986 return new ICmpInst(Pred, BOp0, NegVal);
2987 if (Value *NegVal = dyn_castNegVal(BOp0))
2988 return new ICmpInst(Pred, NegVal, BOp1);
2989 if (BO->hasOneUse()) {
2990 Value *Neg = Builder.CreateNeg(BOp1);
2991 Neg->takeName(BO);
2992 return new ICmpInst(Pred, BOp0, Neg);
2993 }
2994 }
2995 break;
2996 }
2997 case Instruction::Xor:
2998 if (BO->hasOneUse()) {
2999 if (Constant *BOC = dyn_cast<Constant>(BOp1)) {
3000 // For the xor case, we can xor two constants together, eliminating
3001 // the explicit xor.
3002 return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC));
3003 } else if (C.isNullValue()) {
3004 // Replace ((xor A, B) != 0) with (A != B)
3005 return new ICmpInst(Pred, BOp0, BOp1);
3006 }
3007 }
3008 break;
3009 case Instruction::Sub:
3010 if (BO->hasOneUse()) {
3011 // Only check for constant LHS here, as constant RHS will be canonicalized
3012 // to add and use the fold above.
3013 if (Constant *BOC = dyn_cast<Constant>(BOp0)) {
3014 // Replace ((sub BOC, B) != C) with (B != BOC-C).
3015 return new ICmpInst(Pred, BOp1, ConstantExpr::getSub(BOC, RHS));
3016 } else if (C.isNullValue()) {
3017 // Replace ((sub A, B) != 0) with (A != B).
3018 return new ICmpInst(Pred, BOp0, BOp1);
3019 }
3020 }
3021 break;
3022 case Instruction::Or: {
3023 const APInt *BOC;
3024 if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) {
3025 // Comparing if all bits outside of a constant mask are set?
3026 // Replace (X | C) == -1 with (X & ~C) == ~C.
3027 // This removes the -1 constant.
3028 Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
3029 Value *And = Builder.CreateAnd(BOp0, NotBOC);
3030 return new ICmpInst(Pred, And, NotBOC);
3031 }
3032 break;
3033 }
3034 case Instruction::And: {
3035 const APInt *BOC;
3036 if (match(BOp1, m_APInt(BOC))) {
3037 // If we have ((X & C) == C), turn it into ((X & C) != 0).
3038 if (C == *BOC && C.isPowerOf2())
3039 return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
3040 BO, Constant::getNullValue(RHS->getType()));
3041 }
3042 break;
3043 }
3044 case Instruction::UDiv:
3045 if (C.isNullValue()) {
3046 // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
3047 auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
3048 return new ICmpInst(NewPred, BOp1, BOp0);
3049 }
3050 break;
3051 default:
3052 break;
3053 }
3054 return nullptr;
3055}
3056
3057/// Fold an equality icmp with LLVM intrinsic and constant operand.
3058Instruction *InstCombinerImpl::foldICmpEqIntrinsicWithConstant(
3059 ICmpInst &Cmp, IntrinsicInst *II, const APInt &C) {
3060 Type *Ty = II->getType();
3061 unsigned BitWidth = C.getBitWidth();
3062 switch (II->getIntrinsicID()) {
3063 case Intrinsic::abs:
3064 // abs(A) == 0 -> A == 0
3065 // abs(A) == INT_MIN -> A == INT_MIN
3066 if (C.isNullValue() || C.isMinSignedValue())
3067 return new ICmpInst(Cmp.getPredicate(), II->getArgOperand(0),
3068 ConstantInt::get(Ty, C));
3069 break;
3070
3071 case Intrinsic::bswap:
3072 // bswap(A) == C -> A == bswap(C)
3073 return new ICmpInst(Cmp.getPredicate(), II->getArgOperand(0),
3074 ConstantInt::get(Ty, C.byteSwap()));
3075
3076 case Intrinsic::ctlz:
3077 case Intrinsic::cttz: {
3078 // ctz(A) == bitwidth(A) -> A == 0 and likewise for !=
3079 if (C == BitWidth)
3080 return new ICmpInst(Cmp.getPredicate(), II->getArgOperand(0),
3081 ConstantInt::getNullValue(Ty));
3082
3083 // ctz(A) == C -> A & Mask1 == Mask2, where Mask2 only has bit C set
3084 // and Mask1 has bits 0..C+1 set. Similar for ctl, but for high bits.
3085 // Limit to one use to ensure we don't increase instruction count.
3086 unsigned Num = C.getLimitedValue(BitWidth);
3087 if (Num != BitWidth && II->hasOneUse()) {
3088 bool IsTrailing = II->getIntrinsicID() == Intrinsic::cttz;
3089 APInt Mask1 = IsTrailing ? APInt::getLowBitsSet(BitWidth, Num + 1)
3090 : APInt::getHighBitsSet(BitWidth, Num + 1);
3091 APInt Mask2 = IsTrailing
3092 ? APInt::getOneBitSet(BitWidth, Num)
3093 : APInt::getOneBitSet(BitWidth, BitWidth - Num - 1);
3094 return new ICmpInst(Cmp.getPredicate(),
3095 Builder.CreateAnd(II->getArgOperand(0), Mask1),
3096 ConstantInt::get(Ty, Mask2));
3097 }
3098 break;
3099 }
3100
3101 case Intrinsic::ctpop: {
3102 // popcount(A) == 0 -> A == 0 and likewise for !=
3103 // popcount(A) == bitwidth(A) -> A == -1 and likewise for !=
3104 bool IsZero = C.isNullValue();
3105 if (IsZero || C == BitWidth)
3106 return new ICmpInst(Cmp.getPredicate(), II->getArgOperand(0),
3107 IsZero ? Constant::getNullValue(Ty) : Constant::getAllOnesValue(Ty));
3108
3109 break;
3110 }
3111
3112 case Intrinsic::uadd_sat: {
3113 // uadd.sat(a, b) == 0 -> (a | b) == 0
3114 if (C.isNullValue()) {
3115 Value *Or = Builder.CreateOr(II->getArgOperand(0), II->getArgOperand(1));
3116 return new ICmpInst(Cmp.getPredicate(), Or, Constant::getNullValue(Ty));
3117 }
3118 break;
3119 }
3120
3121 case Intrinsic::usub_sat: {
3122 // usub.sat(a, b) == 0 -> a <= b
3123 if (C.isNullValue()) {
3124 ICmpInst::Predicate NewPred = Cmp.getPredicate() == ICmpInst::ICMP_EQ
3125 ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
3126 return new ICmpInst(NewPred, II->getArgOperand(0), II->getArgOperand(1));
3127 }
3128 break;
3129 }
3130 default:
3131 break;
3132 }
3133
3134 return nullptr;
3135}
3136
3137/// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C.
3138Instruction *InstCombinerImpl::foldICmpIntrinsicWithConstant(ICmpInst &Cmp,
3139 IntrinsicInst *II,
3140 const APInt &C) {
3141 if (Cmp.isEquality())
3142 return foldICmpEqIntrinsicWithConstant(Cmp, II, C);
3143
3144 Type *Ty = II->getType();
3145 unsigned BitWidth = C.getBitWidth();
3146 ICmpInst::Predicate Pred = Cmp.getPredicate();
3147 switch (II->getIntrinsicID()) {
3148 case Intrinsic::ctpop: {
3149 // (ctpop X > BitWidth - 1) --> X == -1
3150 Value *X = II->getArgOperand(0);
3151 if (C == BitWidth - 1 && Pred == ICmpInst::ICMP_UGT)
3152 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ, X,
3153 ConstantInt::getAllOnesValue(Ty));
3154 // (ctpop X < BitWidth) --> X != -1
3155 if (C == BitWidth && Pred == ICmpInst::ICMP_ULT)
3156 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_NE, X,
3157 ConstantInt::getAllOnesValue(Ty));
3158 break;
3159 }
3160 case Intrinsic::ctlz: {
3161 // ctlz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX < 0b00010000
3162 if (Pred == ICmpInst::ICMP_UGT && C.ult(BitWidth)) {
3163 unsigned Num = C.getLimitedValue();
3164 APInt Limit = APInt::getOneBitSet(BitWidth, BitWidth - Num - 1);
3165 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_ULT,
3166 II->getArgOperand(0), ConstantInt::get(Ty, Limit));
3167 }
3168
3169 // ctlz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX > 0b00011111
3170 if (Pred == ICmpInst::ICMP_ULT && C.uge(1) && C.ule(BitWidth)) {
3171 unsigned Num = C.getLimitedValue();
3172 APInt Limit = APInt::getLowBitsSet(BitWidth, BitWidth - Num);
3173 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_UGT,
3174 II->getArgOperand(0), ConstantInt::get(Ty, Limit));
3175 }
3176 break;
3177 }
3178 case Intrinsic::cttz: {
3179 // Limit to one use to ensure we don't increase instruction count.
3180 if (!II->hasOneUse())
3181 return nullptr;
3182
3183 // cttz(0bXXXXXXXX) > 3 -> 0bXXXXXXXX & 0b00001111 == 0
3184 if (Pred == ICmpInst::ICMP_UGT && C.ult(BitWidth)) {
3185 APInt Mask = APInt::getLowBitsSet(BitWidth, C.getLimitedValue() + 1);
3186 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_EQ,
3187 Builder.CreateAnd(II->getArgOperand(0), Mask),
3188 ConstantInt::getNullValue(Ty));
3189 }
3190
3191 // cttz(0bXXXXXXXX) < 3 -> 0bXXXXXXXX & 0b00000111 != 0
3192 if (Pred == ICmpInst::ICMP_ULT && C.uge(1) && C.ule(BitWidth)) {
3193 APInt Mask = APInt::getLowBitsSet(BitWidth, C.getLimitedValue());
3194 return CmpInst::Create(Instruction::ICmp, ICmpInst::ICMP_NE,
3195 Builder.CreateAnd(II->getArgOperand(0), Mask),
3196 ConstantInt::getNullValue(Ty));
3197 }
3198 break;
3199 }
3200 default:
3201 break;
3202 }
3203
3204 return nullptr;
3205}
3206
3207/// Handle icmp with constant (but not simple integer constant) RHS.
3208Instruction *InstCombinerImpl::foldICmpInstWithConstantNotInt(ICmpInst &I) {
3209 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3210 Constant *RHSC = dyn_cast<Constant>(Op1);
3211 Instruction *LHSI = dyn_cast<Instruction>(Op0);
3212 if (!RHSC || !LHSI)
3213 return nullptr;
3214
3215 switch (LHSI->getOpcode()) {
3216 case Instruction::GetElementPtr:
3217 // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
3218 if (RHSC->isNullValue() &&
3219 cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
3220 return new ICmpInst(
3221 I.getPredicate(), LHSI->getOperand(0),
3222 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3223 break;
3224 case Instruction::PHI:
3225 // Only fold icmp into the PHI if the phi and icmp are in the same
3226 // block. If in the same block, we're encouraging jump threading. If
3227 // not, we are just pessimizing the code by making an i1 phi.
3228 if (LHSI->getParent() == I.getParent())
3229 if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
3230 return NV;
3231 break;
3232 case Instruction::Select: {
3233 // If either operand of the select is a constant, we can fold the
3234 // comparison into the select arms, which will cause one to be
3235 // constant folded and the select turned into a bitwise or.
3236 Value *Op1 = nullptr, *Op2 = nullptr;
3237 ConstantInt *CI = nullptr;
3238 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
3239 Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
3240 CI = dyn_cast<ConstantInt>(Op1);
3241 }
3242 if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
3243 Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
3244 CI = dyn_cast<ConstantInt>(Op2);
3245 }
3246
3247 // We only want to perform this transformation if it will not lead to
3248 // additional code. This is true if either both sides of the select
3249 // fold to a constant (in which case the icmp is replaced with a select
3250 // which will usually simplify) or this is the only user of the
3251 // select (in which case we are trading a select+icmp for a simpler
3252 // select+icmp) or all uses of the select can be replaced based on
3253 // dominance information ("Global cases").
3254 bool Transform = false;
3255 if (Op1 && Op2)
3256 Transform = true;
3257 else if (Op1 || Op2) {
3258 // Local case
3259 if (LHSI->hasOneUse())
3260 Transform = true;
3261 // Global cases
3262 else if (CI && !CI->isZero())
3263 // When Op1 is constant try replacing select with second operand.
3264 // Otherwise Op2 is constant and try replacing select with first
3265 // operand.
3266 Transform =
3267 replacedSelectWithOperand(cast<SelectInst>(LHSI), &I, Op1 ? 2 : 1);
3268 }
3269 if (Transform) {
3270 if (!Op1)
3271 Op1 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(1), RHSC,
3272 I.getName());
3273 if (!Op2)
3274 Op2 = Builder.CreateICmp(I.getPredicate(), LHSI->getOperand(2), RHSC,
3275 I.getName());
3276 return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
3277 }
3278 break;
3279 }
3280 case Instruction::IntToPtr:
3281 // icmp pred inttoptr(X), null -> icmp pred X, 0
3282 if (RHSC->isNullValue() &&
3283 DL.getIntPtrType(RHSC->getType()) == LHSI->getOperand(0)->getType())
3284 return new ICmpInst(
3285 I.getPredicate(), LHSI->getOperand(0),
3286 Constant::getNullValue(LHSI->getOperand(0)->getType()));
3287 break;
3288
3289 case Instruction::Load:
3290 // Try to optimize things like "A[i] > 4" to index computations.
3291 if (GetElementPtrInst *GEP =
3292 dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
3293 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
3294 if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
3295 !cast<LoadInst>(LHSI)->isVolatile())
3296 if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, I))
3297 return Res;
3298 }
3299 break;
3300 }
3301
3302 return nullptr;
3303}
3304
3305/// Some comparisons can be simplified.
3306/// In this case, we are looking for comparisons that look like
3307/// a check for a lossy truncation.
3308/// Folds:
3309/// icmp SrcPred (x & Mask), x to icmp DstPred x, Mask
3310/// Where Mask is some pattern that produces all-ones in low bits:
3311/// (-1 >> y)
3312/// ((-1 << y) >> y) <- non-canonical, has extra uses
3313/// ~(-1 << y)
3314/// ((1 << y) + (-1)) <- non-canonical, has extra uses
3315/// The Mask can be a constant, too.
3316/// For some predicates, the operands are commutative.
3317/// For others, x can only be on a specific side.
3318static Value *foldICmpWithLowBitMaskedVal(ICmpInst &I,
3319 InstCombiner::BuilderTy &Builder) {
3320 ICmpInst::Predicate SrcPred;
3321 Value *X, *M, *Y;
3322 auto m_VariableMask = m_CombineOr(
3323 m_CombineOr(m_Not(m_Shl(m_AllOnes(), m_Value())),
3324 m_Add(m_Shl(m_One(), m_Value()), m_AllOnes())),
3325 m_CombineOr(m_LShr(m_AllOnes(), m_Value()),
3326 m_LShr(m_Shl(m_AllOnes(), m_Value(Y)), m_Deferred(Y))));
3327 auto m_Mask = m_CombineOr(m_VariableMask, m_LowBitMask());
3328 if (!match(&I, m_c_ICmp(SrcPred,
3329 m_c_And(m_CombineAnd(m_Mask, m_Value(M)), m_Value(X)),
3330 m_Deferred(X))))
3331 return nullptr;
3332
3333 ICmpInst::Predicate DstPred;
3334 switch (SrcPred) {
3335 case ICmpInst::Predicate::ICMP_EQ:
3336 // x & (-1 >> y) == x -> x u<= (-1 >> y)
3337 DstPred = ICmpInst::Predicate::ICMP_ULE;
3338 break;
3339 case ICmpInst::Predicate::ICMP_NE:
3340 // x & (-1 >> y) != x -> x u> (-1 >> y)
3341 DstPred = ICmpInst::Predicate::ICMP_UGT;
3342 break;
3343 case ICmpInst::Predicate::ICMP_ULT:
3344 // x & (-1 >> y) u< x -> x u> (-1 >> y)
3345 // x u> x & (-1 >> y) -> x u> (-1 >> y)
3346 DstPred = ICmpInst::Predicate::ICMP_UGT;
3347 break;
3348 case ICmpInst::Predicate::ICMP_UGE:
3349 // x & (-1 >> y) u>= x -> x u<= (-1 >> y)
3350 // x u<= x & (-1 >> y) -> x u<= (-1 >> y)
3351 DstPred = ICmpInst::Predicate::ICMP_ULE;
3352 break;
3353 case ICmpInst::Predicate::ICMP_SLT:
3354 // x & (-1 >> y) s< x -> x s> (-1 >> y)
3355 // x s> x & (-1 >> y) -> x s> (-1 >> y)
3356 if (!match(M, m_Constant())) // Can not do this fold with non-constant.
3357 return nullptr;
3358 if (!match(M, m_NonNegative())) // Must not have any -1 vector elements.
3359 return nullptr;
3360 DstPred = ICmpInst::Predicate::ICMP_SGT;
3361 break;
3362 case ICmpInst::Predicate::ICMP_SGE:
3363 // x & (-1 >> y) s>= x -> x s<= (-1 >> y)
3364 // x s<= x & (-1 >> y) -> x s<= (-1 >> y)
3365 if (!match(M, m_Constant())) // Can not do this fold with non-constant.
3366 return nullptr;
3367 if (!match(M, m_NonNegative())) // Must not have any -1 vector elements.
3368 return nullptr;
3369 DstPred = ICmpInst::Predicate::ICMP_SLE;
3370 break;
3371 case ICmpInst::Predicate::ICMP_SGT:
3372 case ICmpInst::Predicate::ICMP_SLE:
3373 return nullptr;
3374 case ICmpInst::Predicate::ICMP_UGT:
3375 case ICmpInst::Predicate::ICMP_ULE:
3376 llvm_unreachable("Instsimplify took care of commut. variant")::llvm::llvm_unreachable_internal("Instsimplify took care of commut. variant"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3376)
;
3377 break;
3378 default:
3379 llvm_unreachable("All possible folds are handled.")::llvm::llvm_unreachable_internal("All possible folds are handled."
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3379)
;
3380 }
3381
3382 // The mask value may be a vector constant that has undefined elements. But it
3383 // may not be safe to propagate those undefs into the new compare, so replace
3384 // those elements by copying an existing, defined, and safe scalar constant.
3385 Type *OpTy = M->getType();
3386 auto *VecC = dyn_cast<Constant>(M);
3387 auto *OpVTy = dyn_cast<FixedVectorType>(OpTy);
3388 if (OpVTy && VecC && VecC->containsUndefOrPoisonElement()) {
3389 Constant *SafeReplacementConstant = nullptr;
3390 for (unsigned i = 0, e = OpVTy->getNumElements(); i != e; ++i) {
3391 if (!isa<UndefValue>(VecC->getAggregateElement(i))) {
3392 SafeReplacementConstant = VecC->getAggregateElement(i);
3393 break;
3394 }
3395 }
3396 assert(SafeReplacementConstant && "Failed to find undef replacement")((SafeReplacementConstant && "Failed to find undef replacement"
) ? static_cast<void> (0) : __assert_fail ("SafeReplacementConstant && \"Failed to find undef replacement\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3396, __PRETTY_FUNCTION__))
;
3397 M = Constant::replaceUndefsWith(VecC, SafeReplacementConstant);
3398 }
3399
3400 return Builder.CreateICmp(DstPred, X, M);
3401}
3402
3403/// Some comparisons can be simplified.
3404/// In this case, we are looking for comparisons that look like
3405/// a check for a lossy signed truncation.
3406/// Folds: (MaskedBits is a constant.)
3407/// ((%x << MaskedBits) a>> MaskedBits) SrcPred %x
3408/// Into:
3409/// (add %x, (1 << (KeptBits-1))) DstPred (1 << KeptBits)
3410/// Where KeptBits = bitwidth(%x) - MaskedBits
3411static Value *
3412foldICmpWithTruncSignExtendedVal(ICmpInst &I,
3413 InstCombiner::BuilderTy &Builder) {
3414 ICmpInst::Predicate SrcPred;
3415 Value *X;
3416 const APInt *C0, *C1; // FIXME: non-splats, potentially with undef.
3417 // We are ok with 'shl' having multiple uses, but 'ashr' must be one-use.
3418 if (!match(&I, m_c_ICmp(SrcPred,
3419 m_OneUse(m_AShr(m_Shl(m_Value(X), m_APInt(C0)),
3420 m_APInt(C1))),
3421 m_Deferred(X))))
3422 return nullptr;
3423
3424 // Potential handling of non-splats: for each element:
3425 // * if both are undef, replace with constant 0.
3426 // Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0.
3427 // * if both are not undef, and are different, bailout.
3428 // * else, only one is undef, then pick the non-undef one.
3429
3430 // The shift amount must be equal.
3431 if (*C0 != *C1)
3432 return nullptr;
3433 const APInt &MaskedBits = *C0;
3434 assert(MaskedBits != 0 && "shift by zero should be folded away already.")((MaskedBits != 0 && "shift by zero should be folded away already."
) ? static_cast<void> (0) : __assert_fail ("MaskedBits != 0 && \"shift by zero should be folded away already.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3434, __PRETTY_FUNCTION__))
;
3435
3436 ICmpInst::Predicate DstPred;
3437 switch (SrcPred) {
3438 case ICmpInst::Predicate::ICMP_EQ:
3439 // ((%x << MaskedBits) a>> MaskedBits) == %x
3440 // =>
3441 // (add %x, (1 << (KeptBits-1))) u< (1 << KeptBits)
3442 DstPred = ICmpInst::Predicate::ICMP_ULT;
3443 break;
3444 case ICmpInst::Predicate::ICMP_NE:
3445 // ((%x << MaskedBits) a>> MaskedBits) != %x
3446 // =>
3447 // (add %x, (1 << (KeptBits-1))) u>= (1 << KeptBits)
3448 DstPred = ICmpInst::Predicate::ICMP_UGE;
3449 break;
3450 // FIXME: are more folds possible?
3451 default:
3452 return nullptr;
3453 }
3454
3455 auto *XType = X->getType();
3456 const unsigned XBitWidth = XType->getScalarSizeInBits();
3457 const APInt BitWidth = APInt(XBitWidth, XBitWidth);
3458 assert(BitWidth.ugt(MaskedBits) && "shifts should leave some bits untouched")((BitWidth.ugt(MaskedBits) && "shifts should leave some bits untouched"
) ? static_cast<void> (0) : __assert_fail ("BitWidth.ugt(MaskedBits) && \"shifts should leave some bits untouched\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3458, __PRETTY_FUNCTION__))
;
3459
3460 // KeptBits = bitwidth(%x) - MaskedBits
3461 const APInt KeptBits = BitWidth - MaskedBits;
3462 assert(KeptBits.ugt(0) && KeptBits.ult(BitWidth) && "unreachable")((KeptBits.ugt(0) && KeptBits.ult(BitWidth) &&
"unreachable") ? static_cast<void> (0) : __assert_fail
("KeptBits.ugt(0) && KeptBits.ult(BitWidth) && \"unreachable\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3462, __PRETTY_FUNCTION__))
;
3463 // ICmpCst = (1 << KeptBits)
3464 const APInt ICmpCst = APInt(XBitWidth, 1).shl(KeptBits);
3465 assert(ICmpCst.isPowerOf2())((ICmpCst.isPowerOf2()) ? static_cast<void> (0) : __assert_fail
("ICmpCst.isPowerOf2()", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3465, __PRETTY_FUNCTION__))
;
3466 // AddCst = (1 << (KeptBits-1))
3467 const APInt AddCst = ICmpCst.lshr(1);
3468 assert(AddCst.ult(ICmpCst) && AddCst.isPowerOf2())((AddCst.ult(ICmpCst) && AddCst.isPowerOf2()) ? static_cast
<void> (0) : __assert_fail ("AddCst.ult(ICmpCst) && AddCst.isPowerOf2()"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3468, __PRETTY_FUNCTION__))
;
3469
3470 // T0 = add %x, AddCst
3471 Value *T0 = Builder.CreateAdd(X, ConstantInt::get(XType, AddCst));
3472 // T1 = T0 DstPred ICmpCst
3473 Value *T1 = Builder.CreateICmp(DstPred, T0, ConstantInt::get(XType, ICmpCst));
3474
3475 return T1;
3476}
3477
3478// Given pattern:
3479// icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0
3480// we should move shifts to the same hand of 'and', i.e. rewrite as
3481// icmp eq/ne (and (x shift (Q+K)), y), 0 iff (Q+K) u< bitwidth(x)
3482// We are only interested in opposite logical shifts here.
3483// One of the shifts can be truncated.
3484// If we can, we want to end up creating 'lshr' shift.
3485static Value *
3486foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ,
3487 InstCombiner::BuilderTy &Builder) {
3488 if (!I.isEquality() || !match(I.getOperand(1), m_Zero()) ||
32
Assuming the condition is false
34
Taking false branch
3489 !I.getOperand(0)->hasOneUse())
33
Assuming the condition is false
3490 return nullptr;
3491
3492 auto m_AnyLogicalShift = m_LogicalShift(m_Value(), m_Value());
3493
3494 // Look for an 'and' of two logical shifts, one of which may be truncated.
3495 // We use m_TruncOrSelf() on the RHS to correctly handle commutative case.
3496 Instruction *XShift, *MaybeTruncation, *YShift;
3497 if (!match(
35
Calling 'match<llvm::Value, llvm::PatternMatch::BinaryOp_match<llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, llvm::PatternMatch::match_combine_and<llvm::PatternMatch::match_combine_or<llvm::PatternMatch::CastClass_match<llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, 38>, llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, 28, true>>'
43
Returning from 'match<llvm::Value, llvm::PatternMatch::BinaryOp_match<llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, llvm::PatternMatch::match_combine_and<llvm::PatternMatch::match_combine_or<llvm::PatternMatch::CastClass_match<llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, 38>, llvm::PatternMatch::match_combine_and<llvm::PatternMatch::BinOpPred_match<llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::class_match<llvm::Value>, llvm::PatternMatch::is_logical_shift_op>, llvm::PatternMatch::bind_ty<llvm::Instruction>>>, llvm::PatternMatch::bind_ty<llvm::Instruction>>, 28, true>>'
44
Taking false branch
3498 I.getOperand(0),
3499 m_c_And(m_CombineAnd(m_AnyLogicalShift, m_Instruction(XShift)),
3500 m_CombineAnd(m_TruncOrSelf(m_CombineAnd(
3501 m_AnyLogicalShift, m_Instruction(YShift))),
3502 m_Instruction(MaybeTruncation)))))
3503 return nullptr;
3504
3505 // We potentially looked past 'trunc', but only when matching YShift,
3506 // therefore YShift must have the widest type.
3507 Instruction *WidestShift = YShift;
3508 // Therefore XShift must have the shallowest type.
3509 // Or they both have identical types if there was no truncation.
3510 Instruction *NarrowestShift = XShift;
3511
3512 Type *WidestTy = WidestShift->getType();
3513 Type *NarrowestTy = NarrowestShift->getType();
3514 assert(NarrowestTy == I.getOperand(0)->getType() &&((NarrowestTy == I.getOperand(0)->getType() && "We did not look past any shifts while matching XShift though."
) ? static_cast<void> (0) : __assert_fail ("NarrowestTy == I.getOperand(0)->getType() && \"We did not look past any shifts while matching XShift though.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3515, __PRETTY_FUNCTION__))
45
Assuming the condition is true
46
'?' condition is true
3515 "We did not look past any shifts while matching XShift though.")((NarrowestTy == I.getOperand(0)->getType() && "We did not look past any shifts while matching XShift though."
) ? static_cast<void> (0) : __assert_fail ("NarrowestTy == I.getOperand(0)->getType() && \"We did not look past any shifts while matching XShift though.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3515, __PRETTY_FUNCTION__))
;
3516 bool HadTrunc = WidestTy != I.getOperand(0)->getType();
47
Assuming the condition is false
3517
3518 // If YShift is a 'lshr', swap the shifts around.
3519 if (match(YShift, m_LShr(m_Value(), m_Value())))
48
Taking false branch
3520 std::swap(XShift, YShift);
3521
3522 // The shifts must be in opposite directions.
3523 auto XShiftOpcode = XShift->getOpcode();
3524 if (XShiftOpcode == YShift->getOpcode())
49
Assuming the condition is false
50
Taking false branch
3525 return nullptr; // Do not care about same-direction shifts here.
3526
3527 Value *X, *XShAmt, *Y, *YShAmt;
51
'XShAmt' declared without an initial value
3528 match(XShift, m_BinOp(m_Value(X), m_ZExtOrSelf(m_Value(XShAmt))));
52
Calling 'm_Value'
56
Returning from 'm_Value'
57
Calling 'm_ZExtOrSelf<llvm::PatternMatch::bind_ty<llvm::Value>>'
65
Returning from 'm_ZExtOrSelf<llvm::PatternMatch::bind_ty<llvm::Value>>'
66
Calling 'm_BinOp<llvm::PatternMatch::bind_ty<llvm::Value>, llvm::PatternMatch::match_combine_or<llvm::PatternMatch::CastClass_match<llvm::PatternMatch::bind_ty<llvm::Value>, 39>, llvm::PatternMatch::bind_ty<llvm::Value>>>'
68
Returning from 'm_BinOp<llvm::PatternMatch::bind_ty<llvm::Value>, llvm::PatternMatch::match_combine_or<llvm::PatternMatch::CastClass_match<llvm::PatternMatch::bind_ty<llvm::Value>, 39>, llvm::PatternMatch::bind_ty<llvm::Value>>>'
3529 match(YShift, m_BinOp(m_Value(Y), m_ZExtOrSelf(m_Value(YShAmt))));
3530
3531 // If one of the values being shifted is a constant, then we will end with
3532 // and+icmp, and [zext+]shift instrs will be constant-folded. If they are not,
3533 // however, we will need to ensure that we won't increase instruction count.
3534 if (!isa<Constant>(X) && !isa<Constant>(Y)) {
69
Assuming 'X' is a 'Constant'
3535 // At least one of the hands of the 'and' should be one-use shift.
3536 if (!match(I.getOperand(0),
3537 m_c_And(m_OneUse(m_AnyLogicalShift), m_Value())))
3538 return nullptr;
3539 if (HadTrunc) {
3540 // Due to the 'trunc', we will need to widen X. For that either the old
3541 // 'trunc' or the shift amt in the non-truncated shift should be one-use.
3542 if (!MaybeTruncation->hasOneUse() &&
3543 !NarrowestShift->getOperand(1)->hasOneUse())
3544 return nullptr;
3545 }
3546 }
3547
3548 // We have two shift amounts from two different shifts. The types of those
3549 // shift amounts may not match. If that's the case let's bailout now.
3550 if (XShAmt->getType() != YShAmt->getType())
70
Called C++ object pointer is uninitialized
3551 return nullptr;
3552
3553 // As input, we have the following pattern:
3554 // icmp eq/ne (and ((x shift Q), (y oppositeshift K))), 0
3555 // We want to rewrite that as:
3556 // icmp eq/ne (and (x shift (Q+K)), y), 0 iff (Q+K) u< bitwidth(x)
3557 // While we know that originally (Q+K) would not overflow
3558 // (because 2 * (N-1) u<= iN -1), we have looked past extensions of
3559 // shift amounts. so it may now overflow in smaller bitwidth.
3560 // To ensure that does not happen, we need to ensure that the total maximal
3561 // shift amount is still representable in that smaller bit width.
3562 unsigned MaximalPossibleTotalShiftAmount =
3563 (WidestTy->getScalarSizeInBits() - 1) +
3564 (NarrowestTy->getScalarSizeInBits() - 1);
3565 APInt MaximalRepresentableShiftAmount =
3566 APInt::getAllOnesValue(XShAmt->getType()->getScalarSizeInBits());
3567 if (MaximalRepresentableShiftAmount.ult(MaximalPossibleTotalShiftAmount))
3568 return nullptr;
3569
3570 // Can we fold (XShAmt+YShAmt) ?
3571 auto *NewShAmt = dyn_cast_or_null<Constant>(
3572 SimplifyAddInst(XShAmt, YShAmt, /*isNSW=*/false,
3573 /*isNUW=*/false, SQ.getWithInstruction(&I)));
3574 if (!NewShAmt)
3575 return nullptr;
3576 NewShAmt = ConstantExpr::getZExtOrBitCast(NewShAmt, WidestTy);
3577 unsigned WidestBitWidth = WidestTy->getScalarSizeInBits();
3578
3579 // Is the new shift amount smaller than the bit width?
3580 // FIXME: could also rely on ConstantRange.
3581 if (!match(NewShAmt,
3582 m_SpecificInt_ICMP(ICmpInst::Predicate::ICMP_ULT,
3583 APInt(WidestBitWidth, WidestBitWidth))))
3584 return nullptr;
3585
3586 // An extra legality check is needed if we had trunc-of-lshr.
3587 if (HadTrunc && match(WidestShift, m_LShr(m_Value(), m_Value()))) {
3588 auto CanFold = [NewShAmt, WidestBitWidth, NarrowestShift, SQ,
3589 WidestShift]() {
3590 // It isn't obvious whether it's worth it to analyze non-constants here.
3591 // Also, let's basically give up on non-splat cases, pessimizing vectors.
3592 // If *any* of these preconditions matches we can perform the fold.
3593 Constant *NewShAmtSplat = NewShAmt->getType()->isVectorTy()
3594 ? NewShAmt->getSplatValue()
3595 : NewShAmt;
3596 // If it's edge-case shift (by 0 or by WidestBitWidth-1) we can fold.
3597 if (NewShAmtSplat &&
3598 (NewShAmtSplat->isNullValue() ||
3599 NewShAmtSplat->getUniqueInteger() == WidestBitWidth - 1))
3600 return true;
3601 // We consider *min* leading zeros so a single outlier
3602 // blocks the transform as opposed to allowing it.
3603 if (auto *C = dyn_cast<Constant>(NarrowestShift->getOperand(0))) {
3604 KnownBits Known = computeKnownBits(C, SQ.DL);
3605 unsigned MinLeadZero = Known.countMinLeadingZeros();
3606 // If the value being shifted has at most lowest bit set we can fold.
3607 unsigned MaxActiveBits = Known.getBitWidth() - MinLeadZero;
3608 if (MaxActiveBits <= 1)
3609 return true;
3610 // Precondition: NewShAmt u<= countLeadingZeros(C)
3611 if (NewShAmtSplat && NewShAmtSplat->getUniqueInteger().ule(MinLeadZero))
3612 return true;
3613 }
3614 if (auto *C = dyn_cast<Constant>(WidestShift->getOperand(0))) {
3615 KnownBits Known = computeKnownBits(C, SQ.DL);
3616 unsigned MinLeadZero = Known.countMinLeadingZeros();
3617 // If the value being shifted has at most lowest bit set we can fold.
3618 unsigned MaxActiveBits = Known.getBitWidth() - MinLeadZero;
3619 if (MaxActiveBits <= 1)
3620 return true;
3621 // Precondition: ((WidestBitWidth-1)-NewShAmt) u<= countLeadingZeros(C)
3622 if (NewShAmtSplat) {
3623 APInt AdjNewShAmt =
3624 (WidestBitWidth - 1) - NewShAmtSplat->getUniqueInteger();
3625 if (AdjNewShAmt.ule(MinLeadZero))
3626 return true;
3627 }
3628 }
3629 return false; // Can't tell if it's ok.
3630 };
3631 if (!CanFold())
3632 return nullptr;
3633 }
3634
3635 // All good, we can do this fold.
3636 X = Builder.CreateZExt(X, WidestTy);
3637 Y = Builder.CreateZExt(Y, WidestTy);
3638 // The shift is the same that was for X.
3639 Value *T0 = XShiftOpcode == Instruction::BinaryOps::LShr
3640 ? Builder.CreateLShr(X, NewShAmt)
3641 : Builder.CreateShl(X, NewShAmt);
3642 Value *T1 = Builder.CreateAnd(T0, Y);
3643 return Builder.CreateICmp(I.getPredicate(), T1,
3644 Constant::getNullValue(WidestTy));
3645}
3646
3647/// Fold
3648/// (-1 u/ x) u< y
3649/// ((x * y) u/ x) != y
3650/// to
3651/// @llvm.umul.with.overflow(x, y) plus extraction of overflow bit
3652/// Note that the comparison is commutative, while inverted (u>=, ==) predicate
3653/// will mean that we are looking for the opposite answer.
3654Value *InstCombinerImpl::foldUnsignedMultiplicationOverflowCheck(ICmpInst &I) {
3655 ICmpInst::Predicate Pred;
3656 Value *X, *Y;
3657 Instruction *Mul;
3658 bool NeedNegation;
3659 // Look for: (-1 u/ x) u</u>= y
3660 if (!I.isEquality() &&
3661 match(&I, m_c_ICmp(Pred, m_OneUse(m_UDiv(m_AllOnes(), m_Value(X))),
3662 m_Value(Y)))) {
3663 Mul = nullptr;
3664
3665 // Are we checking that overflow does not happen, or does happen?
3666 switch (Pred) {
3667 case ICmpInst::Predicate::ICMP_ULT:
3668 NeedNegation = false;
3669 break; // OK
3670 case ICmpInst::Predicate::ICMP_UGE:
3671 NeedNegation = true;
3672 break; // OK
3673 default:
3674 return nullptr; // Wrong predicate.
3675 }
3676 } else // Look for: ((x * y) u/ x) !=/== y
3677 if (I.isEquality() &&
3678 match(&I, m_c_ICmp(Pred, m_Value(Y),
3679 m_OneUse(m_UDiv(m_CombineAnd(m_c_Mul(m_Deferred(Y),
3680 m_Value(X)),
3681 m_Instruction(Mul)),
3682 m_Deferred(X)))))) {
3683 NeedNegation = Pred == ICmpInst::Predicate::ICMP_EQ;
3684 } else
3685 return nullptr;
3686
3687 BuilderTy::InsertPointGuard Guard(Builder);
3688 // If the pattern included (x * y), we'll want to insert new instructions
3689 // right before that original multiplication so that we can replace it.
3690 bool MulHadOtherUses = Mul && !Mul->hasOneUse();
3691 if (MulHadOtherUses)
3692 Builder.SetInsertPoint(Mul);
3693
3694 Function *F = Intrinsic::getDeclaration(
3695 I.getModule(), Intrinsic::umul_with_overflow, X->getType());
3696 CallInst *Call = Builder.CreateCall(F, {X, Y}, "umul");
3697
3698 // If the multiplication was used elsewhere, to ensure that we don't leave
3699 // "duplicate" instructions, replace uses of that original multiplication
3700 // with the multiplication result from the with.overflow intrinsic.
3701 if (MulHadOtherUses)
3702 replaceInstUsesWith(*Mul, Builder.CreateExtractValue(Call, 0, "umul.val"));
3703
3704 Value *Res = Builder.CreateExtractValue(Call, 1, "umul.ov");
3705 if (NeedNegation) // This technically increases instruction count.
3706 Res = Builder.CreateNot(Res, "umul.not.ov");
3707
3708 // If we replaced the mul, erase it. Do this after all uses of Builder,
3709 // as the mul is used as insertion point.
3710 if (MulHadOtherUses)
3711 eraseInstFromFunction(*Mul);
3712
3713 return Res;
3714}
3715
3716static Instruction *foldICmpXNegX(ICmpInst &I) {
3717 CmpInst::Predicate Pred;
3718 Value *X;
3719 if (!match(&I, m_c_ICmp(Pred, m_NSWNeg(m_Value(X)), m_Deferred(X))))
3720 return nullptr;
3721
3722 if (ICmpInst::isSigned(Pred))
3723 Pred = ICmpInst::getSwappedPredicate(Pred);
3724 else if (ICmpInst::isUnsigned(Pred))
3725 Pred = ICmpInst::getSignedPredicate(Pred);
3726 // else for equality-comparisons just keep the predicate.
3727
3728 return ICmpInst::Create(Instruction::ICmp, Pred, X,
3729 Constant::getNullValue(X->getType()), I.getName());
3730}
3731
3732/// Try to fold icmp (binop), X or icmp X, (binop).
3733/// TODO: A large part of this logic is duplicated in InstSimplify's
3734/// simplifyICmpWithBinOp(). We should be able to share that and avoid the code
3735/// duplication.
3736Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
3737 const SimplifyQuery &SQ) {
3738 const SimplifyQuery Q = SQ.getWithInstruction(&I);
3739 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3740
3741 // Special logic for binary operators.
3742 BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
1
Assuming 'Op0' is a 'BinaryOperator'
3743 BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
2
Assuming 'Op1' is not a 'BinaryOperator'
3744 if (!BO0
2.1
'BO0' is non-null
2.1
'BO0' is non-null
&& !BO1)
3745 return nullptr;
3746
3747 if (Instruction *NewICmp
2.2
'NewICmp' is null
2.2
'NewICmp' is null
= foldICmpXNegX(I))
3
Taking false branch
3748 return NewICmp;
3749
3750 const CmpInst::Predicate Pred = I.getPredicate();
3751 Value *X;
3752
3753 // Convert add-with-unsigned-overflow comparisons into a 'not' with compare.
3754 // (Op1 + X) u</u>= Op1 --> ~Op1 u</u>= X
3755 if (match(Op0, m_OneUse(m_c_Add(m_Specific(Op1), m_Value(X)))) &&
4
Taking false branch
3756 (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE))
3757 return new ICmpInst(Pred, Builder.CreateNot(Op1), X);
3758 // Op0 u>/u<= (Op0 + X) --> X u>/u<= ~Op0
3759 if (match(Op1, m_OneUse(m_c_Add(m_Specific(Op0), m_Value(X)))) &&
5
Taking false branch
3760 (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULE))
3761 return new ICmpInst(Pred, X, Builder.CreateNot(Op0));
3762
3763 bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
3764 if (BO0
5.1
'BO0' is non-null
5.1
'BO0' is non-null
&& isa<OverflowingBinaryOperator>(BO0))
6
Assuming 'BO0' is not a 'OverflowingBinaryOperator'
7
Taking false branch
3765 NoOp0WrapProblem =
3766 ICmpInst::isEquality(Pred) ||
3767 (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
3768 (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
3769 if (BO1
7.1
'BO1' is null
7.1
'BO1' is null
&& isa<OverflowingBinaryOperator>(BO1))
3770 NoOp1WrapProblem =
3771 ICmpInst::isEquality(Pred) ||
3772 (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
3773 (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
3774
3775 // Analyze the case when either Op0 or Op1 is an add instruction.
3776 // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
3777 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
3778 if (BO0
7.2
'BO0' is non-null
7.2
'BO0' is non-null
&& BO0->getOpcode() == Instruction::Add) {
8
Assuming the condition is false
9
Taking false branch
3779 A = BO0->getOperand(0);
3780 B = BO0->getOperand(1);
3781 }
3782 if (BO1
9.1
'BO1' is null
9.1
'BO1' is null
&& BO1->getOpcode() == Instruction::Add) {
3783 C = BO1->getOperand(0);
3784 D = BO1->getOperand(1);
3785 }
3786
3787 // icmp (A+B), A -> icmp B, 0 for equalities or if there is no overflow.
3788 // icmp (A+B), B -> icmp A, 0 for equalities or if there is no overflow.
3789 if ((A
9.2
'A' is not equal to 'Op1'
9.2
'A' is not equal to 'Op1'
== Op1 || B
9.3
'B' is not equal to 'Op1'
9.3
'B' is not equal to 'Op1'
== Op1) && NoOp0WrapProblem)
3790 return new ICmpInst(Pred, A == Op1 ? B : A,
3791 Constant::getNullValue(Op1->getType()));
3792
3793 // icmp C, (C+D) -> icmp 0, D for equalities or if there is no overflow.
3794 // icmp D, (C+D) -> icmp 0, C for equalities or if there is no overflow.
3795 if ((C
9.4
'C' is not equal to 'Op0'
9.4
'C' is not equal to 'Op0'
== Op0 || D
9.5
'D' is not equal to 'Op0'
9.5
'D' is not equal to 'Op0'
== Op0) && NoOp1WrapProblem)
3796 return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
3797 C == Op0 ? D : C);
3798
3799 // icmp (A+B), (A+D) -> icmp B, D for equalities or if there is no overflow.
3800 if (A
9.6
'A' is null
9.6
'A' is null
&& C && (A == C || A == D || B == C || B == D) && NoOp0WrapProblem &&
3801 NoOp1WrapProblem) {
3802 // Determine Y and Z in the form icmp (X+Y), (X+Z).
3803 Value *Y, *Z;
3804 if (A == C) {
3805 // C + B == C + D -> B == D
3806 Y = B;
3807 Z = D;
3808 } else if (A == D) {
3809 // D + B == C + D -> B == C
3810 Y = B;
3811 Z = C;
3812 } else if (B == C) {
3813 // A + C == C + D -> A == D
3814 Y = A;
3815 Z = D;
3816 } else {
3817 assert(B == D)((B == D) ? static_cast<void> (0) : __assert_fail ("B == D"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 3817, __PRETTY_FUNCTION__))
;
3818 // A + D == C + D -> A == C
3819 Y = A;
3820 Z = C;
3821 }
3822 return new ICmpInst(Pred, Y, Z);
3823 }
3824
3825 // icmp slt (A + -1), Op1 -> icmp sle A, Op1
3826 if (A
9.7
'A' is null
9.7
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
10
Taking false branch
3827 match(B, m_AllOnes()))
3828 return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
3829
3830 // icmp sge (A + -1), Op1 -> icmp sgt A, Op1
3831 if (A
10.1
'A' is null
10.1
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
11
Taking false branch
3832 match(B, m_AllOnes()))
3833 return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
3834
3835 // icmp sle (A + 1), Op1 -> icmp slt A, Op1
3836 if (A
11.1
'A' is null
11.1
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE && match(B, m_One()))
12
Taking false branch
3837 return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
3838
3839 // icmp sgt (A + 1), Op1 -> icmp sge A, Op1
3840 if (A
12.1
'A' is null
12.1
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT && match(B, m_One()))
13
Taking false branch
3841 return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
3842
3843 // icmp sgt Op0, (C + -1) -> icmp sge Op0, C
3844 if (C
13.1
'C' is null
13.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_SGT &&
14
Taking false branch
3845 match(D, m_AllOnes()))
3846 return new ICmpInst(CmpInst::ICMP_SGE, Op0, C);
3847
3848 // icmp sle Op0, (C + -1) -> icmp slt Op0, C
3849 if (C
14.1
'C' is null
14.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_SLE &&
15
Taking false branch
3850 match(D, m_AllOnes()))
3851 return new ICmpInst(CmpInst::ICMP_SLT, Op0, C);
3852
3853 // icmp sge Op0, (C + 1) -> icmp sgt Op0, C
3854 if (C
15.1
'C' is null
15.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_SGE && match(D, m_One()))
16
Taking false branch
3855 return new ICmpInst(CmpInst::ICMP_SGT, Op0, C);
3856
3857 // icmp slt Op0, (C + 1) -> icmp sle Op0, C
3858 if (C
16.1
'C' is null
16.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_SLT && match(D, m_One()))
17
Taking false branch
3859 return new ICmpInst(CmpInst::ICMP_SLE, Op0, C);
3860
3861 // TODO: The subtraction-related identities shown below also hold, but
3862 // canonicalization from (X -nuw 1) to (X + -1) means that the combinations
3863 // wouldn't happen even if they were implemented.
3864 //
3865 // icmp ult (A - 1), Op1 -> icmp ule A, Op1
3866 // icmp uge (A - 1), Op1 -> icmp ugt A, Op1
3867 // icmp ugt Op0, (C - 1) -> icmp uge Op0, C
3868 // icmp ule Op0, (C - 1) -> icmp ult Op0, C
3869
3870 // icmp ule (A + 1), Op0 -> icmp ult A, Op1
3871 if (A
17.1
'A' is null
17.1
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_ULE && match(B, m_One()))
18
Taking false branch
3872 return new ICmpInst(CmpInst::ICMP_ULT, A, Op1);
3873
3874 // icmp ugt (A + 1), Op0 -> icmp uge A, Op1
3875 if (A
18.1
'A' is null
18.1
'A' is null
&& NoOp0WrapProblem && Pred == CmpInst::ICMP_UGT && match(B, m_One()))
19
Taking false branch
3876 return new ICmpInst(CmpInst::ICMP_UGE, A, Op1);
3877
3878 // icmp uge Op0, (C + 1) -> icmp ugt Op0, C
3879 if (C
19.1
'C' is null
19.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_UGE && match(D, m_One()))
20
Taking false branch
3880 return new ICmpInst(CmpInst::ICMP_UGT, Op0, C);
3881
3882 // icmp ult Op0, (C + 1) -> icmp ule Op0, C
3883 if (C
20.1
'C' is null
20.1
'C' is null
&& NoOp1WrapProblem && Pred == CmpInst::ICMP_ULT && match(D, m_One()))
21
Taking false branch
3884 return new ICmpInst(CmpInst::ICMP_ULE, Op0, C);
3885
3886 // if C1 has greater magnitude than C2:
3887 // icmp (A + C1), (C + C2) -> icmp (A + C3), C
3888 // s.t. C3 = C1 - C2
3889 //
3890 // if C2 has greater magnitude than C1:
3891 // icmp (A + C1), (C + C2) -> icmp A, (C + C3)
3892 // s.t. C3 = C2 - C1
3893 if (A
21.1
'A' is null
21.1
'A' is null
&& C && NoOp0WrapProblem && NoOp1WrapProblem &&
3894 (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
3895 if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
3896 if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
3897 const APInt &AP1 = C1->getValue();
3898 const APInt &AP2 = C2->getValue();
3899 if (AP1.isNegative() == AP2.isNegative()) {
3900 APInt AP1Abs = C1->getValue().abs();
3901 APInt AP2Abs = C2->getValue().abs();
3902 if (AP1Abs.uge(AP2Abs)) {
3903 ConstantInt *C3 = Builder.getInt(AP1 - AP2);
3904 Value *NewAdd = Builder.CreateNSWAdd(A, C3);
3905 return new ICmpInst(Pred, NewAdd, C);
3906 } else {
3907 ConstantInt *C3 = Builder.getInt(AP2 - AP1);
3908 Value *NewAdd = Builder.CreateNSWAdd(C, C3);
3909 return new ICmpInst(Pred, A, NewAdd);
3910 }
3911 }
3912 }
3913
3914 // Analyze the case when either Op0 or Op1 is a sub instruction.
3915 // Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
3916 A = nullptr;
3917 B = nullptr;
3918 C = nullptr;
3919 D = nullptr;
3920 if (BO0
21.2
'BO0' is non-null
21.2
'BO0' is non-null
&& BO0->getOpcode() == Instruction::Sub) {
22
Assuming the condition is false
23
Taking false branch
3921 A = BO0->getOperand(0);
3922 B = BO0->getOperand(1);
3923 }
3924 if (BO1
23.1
'BO1' is null
23.1
'BO1' is null
&& BO1->getOpcode() == Instruction::Sub) {
3925 C = BO1->getOperand(0);
3926 D = BO1->getOperand(1);
3927 }
3928
3929 // icmp (A-B), A -> icmp 0, B for equalities or if there is no overflow.
3930 if (A
23.2
'A' is not equal to 'Op1'
23.2
'A' is not equal to 'Op1'
== Op1 && NoOp0WrapProblem)
3931 return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
3932 // icmp C, (C-D) -> icmp D, 0 for equalities or if there is no overflow.
3933 if (C
23.3
'C' is not equal to 'Op0'
23.3
'C' is not equal to 'Op0'
== Op0 && NoOp1WrapProblem)
3934 return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
3935
3936 // Convert sub-with-unsigned-overflow comparisons into a comparison of args.
3937 // (A - B) u>/u<= A --> B u>/u<= A
3938 if (A
23.4
'A' is not equal to 'Op1'
23.4
'A' is not equal to 'Op1'
== Op1 && (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULE))
3939 return new ICmpInst(Pred, B, A);
3940 // C u</u>= (C - D) --> C u</u>= D
3941 if (C
23.5
'C' is not equal to 'Op0'
23.5
'C' is not equal to 'Op0'
== Op0 && (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE))
3942 return new ICmpInst(Pred, C, D);
3943 // (A - B) u>=/u< A --> B u>/u<= A iff B != 0
3944 if (A
23.6
'A' is not equal to 'Op1'
23.6
'A' is not equal to 'Op1'
== Op1 && (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_ULT) &&
3945 isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
3946 return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred), B, A);
3947 // C u<=/u> (C - D) --> C u</u>= D iff B != 0
3948 if (C
23.7
'C' is not equal to 'Op0'
23.7
'C' is not equal to 'Op0'
== Op0 && (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_UGT) &&
3949 isKnownNonZero(D, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
3950 return new ICmpInst(CmpInst::getFlippedStrictnessPredicate(Pred), C, D);
3951
3952 // icmp (A-B), (C-B) -> icmp A, C for equalities or if there is no overflow.
3953 if (B
23.8
'B' is null
23.8
'B' is null
&& D && B == D && NoOp0WrapProblem && NoOp1WrapProblem)
3954 return new ICmpInst(Pred, A, C);
3955
3956 // icmp (A-B), (A-D) -> icmp D, B for equalities or if there is no overflow.
3957 if (A
23.9
'A' is null
23.9
'A' is null
&& C && A == C && NoOp0WrapProblem && NoOp1WrapProblem)
3958 return new ICmpInst(Pred, D, B);
3959
3960 // icmp (0-X) < cst --> x > -cst
3961 if (NoOp0WrapProblem
23.10
'NoOp0WrapProblem' is false
23.10
'NoOp0WrapProblem' is false
&& ICmpInst::isSigned(Pred)) {
3962 Value *X;
3963 if (match(BO0, m_Neg(m_Value(X))))
3964 if (Constant *RHSC = dyn_cast<Constant>(Op1))
3965 if (RHSC->isNotMinSignedValue())
3966 return new ICmpInst(I.getSwappedPredicate(), X,
3967 ConstantExpr::getNeg(RHSC));
3968 }
3969
3970 {
3971 // Try to remove shared constant multiplier from equality comparison:
3972 // X * C == Y * C (with no overflowing/aliasing) --> X == Y
3973 Value *X, *Y;
3974 const APInt *C;
3975 if (match(Op0, m_Mul(m_Value(X), m_APInt(C))) && *C != 0 &&
24
Taking false branch
3976 match(Op1, m_Mul(m_Value(Y), m_SpecificInt(*C))) && I.isEquality())
3977 if (!C->countTrailingZeros() ||
3978 (BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap()) ||
3979 (BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap()))
3980 return new ICmpInst(Pred, X, Y);
3981 }
3982
3983 BinaryOperator *SRem = nullptr;
3984 // icmp (srem X, Y), Y
3985 if (BO0
24.1
'BO0' is non-null
24.1
'BO0' is non-null
&& BO0->getOpcode() == Instruction::SRem && Op1 == BO0->getOperand(1))
25
Assuming the condition is false
3986 SRem = BO0;
3987 // icmp Y, (srem X, Y)
3988 else if (BO1
25.1
'BO1' is null
25.1
'BO1' is null
&& BO1->getOpcode() == Instruction::SRem &&
3989 Op0 == BO1->getOperand(1))
3990 SRem = BO1;
3991 if (SRem
25.2
'SRem' is null
25.2
'SRem' is null
) {
26
Taking false branch
3992 // We don't check hasOneUse to avoid increasing register pressure because
3993 // the value we use is the same value this instruction was already using.
3994 switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
3995 default:
3996 break;
3997 case ICmpInst::ICMP_EQ:
3998 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
3999 case ICmpInst::ICMP_NE:
4000 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
4001 case ICmpInst::ICMP_SGT:
4002 case ICmpInst::ICMP_SGE:
4003 return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
4004 Constant::getAllOnesValue(SRem->getType()));
4005 case ICmpInst::ICMP_SLT:
4006 case ICmpInst::ICMP_SLE:
4007 return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
4008 Constant::getNullValue(SRem->getType()));
4009 }
4010 }
4011
4012 if (BO0
26.1
'BO0' is non-null
26.1
'BO0' is non-null
&& BO1
26.2
'BO1' is null
26.2
'BO1' is null
&& BO0->getOpcode() == BO1->getOpcode() && BO0->hasOneUse() &&
4013 BO1->hasOneUse() && BO0->getOperand(1) == BO1->getOperand(1)) {
4014 switch (BO0->getOpcode()) {
4015 default:
4016 break;
4017 case Instruction::Add:
4018 case Instruction::Sub:
4019 case Instruction::Xor: {
4020 if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
4021 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
4022
4023 const APInt *C;
4024 if (match(BO0->getOperand(1), m_APInt(C))) {
4025 // icmp u/s (a ^ signmask), (b ^ signmask) --> icmp s/u a, b
4026 if (C->isSignMask()) {
4027 ICmpInst::Predicate NewPred = I.getFlippedSignednessPredicate();
4028 return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
4029 }
4030
4031 // icmp u/s (a ^ maxsignval), (b ^ maxsignval) --> icmp s/u' a, b
4032 if (BO0->getOpcode() == Instruction::Xor && C->isMaxSignedValue()) {
4033 ICmpInst::Predicate NewPred = I.getFlippedSignednessPredicate();
4034 NewPred = I.getSwappedPredicate(NewPred);
4035 return new ICmpInst(NewPred, BO0->getOperand(0), BO1->getOperand(0));
4036 }
4037 }
4038 break;
4039 }
4040 case Instruction::Mul: {
4041 if (!I.isEquality())
4042 break;
4043
4044 const APInt *C;
4045 if (match(BO0->getOperand(1), m_APInt(C)) && !C->isNullValue() &&
4046 !C->isOneValue()) {
4047 // icmp eq/ne (X * C), (Y * C) --> icmp (X & Mask), (Y & Mask)
4048 // Mask = -1 >> count-trailing-zeros(C).
4049 if (unsigned TZs = C->countTrailingZeros()) {
4050 Constant *Mask = ConstantInt::get(
4051 BO0->getType(),
4052 APInt::getLowBitsSet(C->getBitWidth(), C->getBitWidth() - TZs));
4053 Value *And1 = Builder.CreateAnd(BO0->getOperand(0), Mask);
4054 Value *And2 = Builder.CreateAnd(BO1->getOperand(0), Mask);
4055 return new ICmpInst(Pred, And1, And2);
4056 }
4057 }
4058 break;
4059 }
4060 case Instruction::UDiv:
4061 case Instruction::LShr:
4062 if (I.isSigned() || !BO0->isExact() || !BO1->isExact())
4063 break;
4064 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
4065
4066 case Instruction::SDiv:
4067 if (!I.isEquality() || !BO0->isExact() || !BO1->isExact())
4068 break;
4069 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
4070
4071 case Instruction::AShr:
4072 if (!BO0->isExact() || !BO1->isExact())
4073 break;
4074 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
4075
4076 case Instruction::Shl: {
4077 bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
4078 bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
4079 if (!NUW && !NSW)
4080 break;
4081 if (!NSW && I.isSigned())
4082 break;
4083 return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
4084 }
4085 }
4086 }
4087
4088 if (BO0
26.3
'BO0' is non-null
26.3
'BO0' is non-null
) {
27
Taking true branch
4089 // Transform A & (L - 1) `ult` L --> L != 0
4090 auto LSubOne = m_Add(m_Specific(Op1), m_AllOnes());
4091 auto BitwiseAnd = m_c_And(m_Value(), LSubOne);
4092
4093 if (match(BO0, BitwiseAnd) && Pred == ICmpInst::ICMP_ULT) {
4094 auto *Zero = Constant::getNullValue(BO0->getType());
4095 return new ICmpInst(ICmpInst::ICMP_NE, Op1, Zero);
4096 }
4097 }
4098
4099 if (Value *V
27.1
'V' is null
27.1
'V' is null
= foldUnsignedMultiplicationOverflowCheck(I))
28
Taking false branch
4100 return replaceInstUsesWith(I, V);
4101
4102 if (Value *V
28.1
'V' is null
28.1
'V' is null
= foldICmpWithLowBitMaskedVal(I, Builder))
29
Taking false branch
4103 return replaceInstUsesWith(I, V);
4104
4105 if (Value *V
29.1
'V' is null
29.1
'V' is null
= foldICmpWithTruncSignExtendedVal(I, Builder))
30
Taking false branch
4106 return replaceInstUsesWith(I, V);
4107
4108 if (Value *V = foldShiftIntoShiftInAnotherHandOfAndInICmp(I, SQ, Builder))
31
Calling 'foldShiftIntoShiftInAnotherHandOfAndInICmp'
4109 return replaceInstUsesWith(I, V);
4110
4111 return nullptr;
4112}
4113
4114/// Fold icmp Pred min|max(X, Y), X.
4115static Instruction *foldICmpWithMinMax(ICmpInst &Cmp) {
4116 ICmpInst::Predicate Pred = Cmp.getPredicate();
4117 Value *Op0 = Cmp.getOperand(0);
4118 Value *X = Cmp.getOperand(1);
4119
4120 // Canonicalize minimum or maximum operand to LHS of the icmp.
4121 if (match(X, m_c_SMin(m_Specific(Op0), m_Value())) ||
4122 match(X, m_c_SMax(m_Specific(Op0), m_Value())) ||
4123 match(X, m_c_UMin(m_Specific(Op0), m_Value())) ||
4124 match(X, m_c_UMax(m_Specific(Op0), m_Value()))) {
4125 std::swap(Op0, X);
4126 Pred = Cmp.getSwappedPredicate();
4127 }
4128
4129 Value *Y;
4130 if (match(Op0, m_c_SMin(m_Specific(X), m_Value(Y)))) {
4131 // smin(X, Y) == X --> X s<= Y
4132 // smin(X, Y) s>= X --> X s<= Y
4133 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SGE)
4134 return new ICmpInst(ICmpInst::ICMP_SLE, X, Y);
4135
4136 // smin(X, Y) != X --> X s> Y
4137 // smin(X, Y) s< X --> X s> Y
4138 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SLT)
4139 return new ICmpInst(ICmpInst::ICMP_SGT, X, Y);
4140
4141 // These cases should be handled in InstSimplify:
4142 // smin(X, Y) s<= X --> true
4143 // smin(X, Y) s> X --> false
4144 return nullptr;
4145 }
4146
4147 if (match(Op0, m_c_SMax(m_Specific(X), m_Value(Y)))) {
4148 // smax(X, Y) == X --> X s>= Y
4149 // smax(X, Y) s<= X --> X s>= Y
4150 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_SLE)
4151 return new ICmpInst(ICmpInst::ICMP_SGE, X, Y);
4152
4153 // smax(X, Y) != X --> X s< Y
4154 // smax(X, Y) s> X --> X s< Y
4155 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_SGT)
4156 return new ICmpInst(ICmpInst::ICMP_SLT, X, Y);
4157
4158 // These cases should be handled in InstSimplify:
4159 // smax(X, Y) s>= X --> true
4160 // smax(X, Y) s< X --> false
4161 return nullptr;
4162 }
4163
4164 if (match(Op0, m_c_UMin(m_Specific(X), m_Value(Y)))) {
4165 // umin(X, Y) == X --> X u<= Y
4166 // umin(X, Y) u>= X --> X u<= Y
4167 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_UGE)
4168 return new ICmpInst(ICmpInst::ICMP_ULE, X, Y);
4169
4170 // umin(X, Y) != X --> X u> Y
4171 // umin(X, Y) u< X --> X u> Y
4172 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_ULT)
4173 return new ICmpInst(ICmpInst::ICMP_UGT, X, Y);
4174
4175 // These cases should be handled in InstSimplify:
4176 // umin(X, Y) u<= X --> true
4177 // umin(X, Y) u> X --> false
4178 return nullptr;
4179 }
4180
4181 if (match(Op0, m_c_UMax(m_Specific(X), m_Value(Y)))) {
4182 // umax(X, Y) == X --> X u>= Y
4183 // umax(X, Y) u<= X --> X u>= Y
4184 if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_ULE)
4185 return new ICmpInst(ICmpInst::ICMP_UGE, X, Y);
4186
4187 // umax(X, Y) != X --> X u< Y
4188 // umax(X, Y) u> X --> X u< Y
4189 if (Pred == CmpInst::ICMP_NE || Pred == CmpInst::ICMP_UGT)
4190 return new ICmpInst(ICmpInst::ICMP_ULT, X, Y);
4191
4192 // These cases should be handled in InstSimplify:
4193 // umax(X, Y) u>= X --> true
4194 // umax(X, Y) u< X --> false
4195 return nullptr;
4196 }
4197
4198 return nullptr;
4199}
4200
4201Instruction *InstCombinerImpl::foldICmpEquality(ICmpInst &I) {
4202 if (!I.isEquality())
4203 return nullptr;
4204
4205 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4206 const CmpInst::Predicate Pred = I.getPredicate();
4207 Value *A, *B, *C, *D;
4208 if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
4209 if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
4210 Value *OtherVal = A == Op1 ? B : A;
4211 return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType()));
4212 }
4213
4214 if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
4215 // A^c1 == C^c2 --> A == C^(c1^c2)
4216 ConstantInt *C1, *C2;
4217 if (match(B, m_ConstantInt(C1)) && match(D, m_ConstantInt(C2)) &&
4218 Op1->hasOneUse()) {
4219 Constant *NC = Builder.getInt(C1->getValue() ^ C2->getValue());
4220 Value *Xor = Builder.CreateXor(C, NC);
4221 return new ICmpInst(Pred, A, Xor);
4222 }
4223
4224 // A^B == A^D -> B == D
4225 if (A == C)
4226 return new ICmpInst(Pred, B, D);
4227 if (A == D)
4228 return new ICmpInst(Pred, B, C);
4229 if (B == C)
4230 return new ICmpInst(Pred, A, D);
4231 if (B == D)
4232 return new ICmpInst(Pred, A, C);
4233 }
4234 }
4235
4236 if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && (A == Op0 || B == Op0)) {
4237 // A == (A^B) -> B == 0
4238 Value *OtherVal = A == Op0 ? B : A;
4239 return new ICmpInst(Pred, OtherVal, Constant::getNullValue(A->getType()));
4240 }
4241
4242 // (X&Z) == (Y&Z) -> (X^Y) & Z == 0
4243 if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
4244 match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
4245 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
4246
4247 if (A == C) {
4248 X = B;
4249 Y = D;
4250 Z = A;
4251 } else if (A == D) {
4252 X = B;
4253 Y = C;
4254 Z = A;
4255 } else if (B == C) {
4256 X = A;
4257 Y = D;
4258 Z = B;
4259 } else if (B == D) {
4260 X = A;
4261 Y = C;
4262 Z = B;
4263 }
4264
4265 if (X) { // Build (X^Y) & Z
4266 Op1 = Builder.CreateXor(X, Y);
4267 Op1 = Builder.CreateAnd(Op1, Z);
4268 return new ICmpInst(Pred, Op1, Constant::getNullValue(Op1->getType()));
4269 }
4270 }
4271
4272 // Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
4273 // and (B & (1<<X)-1) == (zext A) --> A == (trunc B)
4274 ConstantInt *Cst1;
4275 if ((Op0->hasOneUse() && match(Op0, m_ZExt(m_Value(A))) &&
4276 match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
4277 (Op1->hasOneUse() && match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
4278 match(Op1, m_ZExt(m_Value(A))))) {
4279 APInt Pow2 = Cst1->getValue() + 1;
4280 if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
4281 Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
4282 return new ICmpInst(Pred, A, Builder.CreateTrunc(B, A->getType()));
4283 }
4284
4285 // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
4286 // For lshr and ashr pairs.
4287 if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
4288 match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
4289 (match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
4290 match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
4291 unsigned TypeBits = Cst1->getBitWidth();
4292 unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
4293 if (ShAmt < TypeBits && ShAmt != 0) {
4294 ICmpInst::Predicate NewPred =
4295 Pred == ICmpInst::ICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
4296 Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted");
4297 APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
4298 return new ICmpInst(NewPred, Xor, Builder.getInt(CmpVal));
4299 }
4300 }
4301
4302 // (A << C) == (B << C) --> ((A^B) & (~0U >> C)) == 0
4303 if (match(Op0, m_OneUse(m_Shl(m_Value(A), m_ConstantInt(Cst1)))) &&
4304 match(Op1, m_OneUse(m_Shl(m_Value(B), m_Specific(Cst1))))) {
4305 unsigned TypeBits = Cst1->getBitWidth();
4306 unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
4307 if (ShAmt < TypeBits && ShAmt != 0) {
4308 Value *Xor = Builder.CreateXor(A, B, I.getName() + ".unshifted");
4309 APInt AndVal = APInt::getLowBitsSet(TypeBits, TypeBits - ShAmt);
4310 Value *And = Builder.CreateAnd(Xor, Builder.getInt(AndVal),
4311 I.getName() + ".mask");
4312 return new ICmpInst(Pred, And, Constant::getNullValue(Cst1->getType()));
4313 }
4314 }
4315
4316 // Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
4317 // "icmp (and X, mask), cst"
4318 uint64_t ShAmt = 0;
4319 if (Op0->hasOneUse() &&
4320 match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A), m_ConstantInt(ShAmt))))) &&
4321 match(Op1, m_ConstantInt(Cst1)) &&
4322 // Only do this when A has multiple uses. This is most important to do
4323 // when it exposes other optimizations.
4324 !A->hasOneUse()) {
4325 unsigned ASize = cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
4326
4327 if (ShAmt < ASize) {
4328 APInt MaskV =
4329 APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits());
4330 MaskV <<= ShAmt;
4331
4332 APInt CmpV = Cst1->getValue().zext(ASize);
4333 CmpV <<= ShAmt;
4334
4335 Value *Mask = Builder.CreateAnd(A, Builder.getInt(MaskV));
4336 return new ICmpInst(Pred, Mask, Builder.getInt(CmpV));
4337 }
4338 }
4339
4340 // If both operands are byte-swapped or bit-reversed, just compare the
4341 // original values.
4342 // TODO: Move this to a function similar to foldICmpIntrinsicWithConstant()
4343 // and handle more intrinsics.
4344 if ((match(Op0, m_BSwap(m_Value(A))) && match(Op1, m_BSwap(m_Value(B)))) ||
4345 (match(Op0, m_BitReverse(m_Value(A))) &&
4346 match(Op1, m_BitReverse(m_Value(B)))))
4347 return new ICmpInst(Pred, A, B);
4348
4349 // Canonicalize checking for a power-of-2-or-zero value:
4350 // (A & (A-1)) == 0 --> ctpop(A) < 2 (two commuted variants)
4351 // ((A-1) & A) != 0 --> ctpop(A) > 1 (two commuted variants)
4352 if (!match(Op0, m_OneUse(m_c_And(m_Add(m_Value(A), m_AllOnes()),
4353 m_Deferred(A)))) ||
4354 !match(Op1, m_ZeroInt()))
4355 A = nullptr;
4356
4357 // (A & -A) == A --> ctpop(A) < 2 (four commuted variants)
4358 // (-A & A) != A --> ctpop(A) > 1 (four commuted variants)
4359 if (match(Op0, m_OneUse(m_c_And(m_Neg(m_Specific(Op1)), m_Specific(Op1)))))
4360 A = Op1;
4361 else if (match(Op1,
4362 m_OneUse(m_c_And(m_Neg(m_Specific(Op0)), m_Specific(Op0)))))
4363 A = Op0;
4364
4365 if (A) {
4366 Type *Ty = A->getType();
4367 CallInst *CtPop = Builder.CreateUnaryIntrinsic(Intrinsic::ctpop, A);
4368 return Pred == ICmpInst::ICMP_EQ
4369 ? new ICmpInst(ICmpInst::ICMP_ULT, CtPop, ConstantInt::get(Ty, 2))
4370 : new ICmpInst(ICmpInst::ICMP_UGT, CtPop, ConstantInt::get(Ty, 1));
4371 }
4372
4373 return nullptr;
4374}
4375
4376static Instruction *foldICmpWithZextOrSext(ICmpInst &ICmp,
4377 InstCombiner::BuilderTy &Builder) {
4378 assert(isa<CastInst>(ICmp.getOperand(0)) && "Expected cast for operand 0")((isa<CastInst>(ICmp.getOperand(0)) && "Expected cast for operand 0"
) ? static_cast<void> (0) : __assert_fail ("isa<CastInst>(ICmp.getOperand(0)) && \"Expected cast for operand 0\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4378, __PRETTY_FUNCTION__))
;
4379 auto *CastOp0 = cast<CastInst>(ICmp.getOperand(0));
4380 Value *X;
4381 if (!match(CastOp0, m_ZExtOrSExt(m_Value(X))))
4382 return nullptr;
4383
4384 bool IsSignedExt = CastOp0->getOpcode() == Instruction::SExt;
4385 bool IsSignedCmp = ICmp.isSigned();
4386 if (auto *CastOp1 = dyn_cast<CastInst>(ICmp.getOperand(1))) {
4387 // If the signedness of the two casts doesn't agree (i.e. one is a sext
4388 // and the other is a zext), then we can't handle this.
4389 // TODO: This is too strict. We can handle some predicates (equality?).
4390 if (CastOp0->getOpcode() != CastOp1->getOpcode())
4391 return nullptr;
4392
4393 // Not an extension from the same type?
4394 Value *Y = CastOp1->getOperand(0);
4395 Type *XTy = X->getType(), *YTy = Y->getType();
4396 if (XTy != YTy) {
4397 // One of the casts must have one use because we are creating a new cast.
4398 if (!CastOp0->hasOneUse() && !CastOp1->hasOneUse())
4399 return nullptr;
4400 // Extend the narrower operand to the type of the wider operand.
4401 if (XTy->getScalarSizeInBits() < YTy->getScalarSizeInBits())
4402 X = Builder.CreateCast(CastOp0->getOpcode(), X, YTy);
4403 else if (YTy->getScalarSizeInBits() < XTy->getScalarSizeInBits())
4404 Y = Builder.CreateCast(CastOp0->getOpcode(), Y, XTy);
4405 else
4406 return nullptr;
4407 }
4408
4409 // (zext X) == (zext Y) --> X == Y
4410 // (sext X) == (sext Y) --> X == Y
4411 if (ICmp.isEquality())
4412 return new ICmpInst(ICmp.getPredicate(), X, Y);
4413
4414 // A signed comparison of sign extended values simplifies into a
4415 // signed comparison.
4416 if (IsSignedCmp && IsSignedExt)
4417 return new ICmpInst(ICmp.getPredicate(), X, Y);
4418
4419 // The other three cases all fold into an unsigned comparison.
4420 return new ICmpInst(ICmp.getUnsignedPredicate(), X, Y);
4421 }
4422
4423 // Below here, we are only folding a compare with constant.
4424 auto *C = dyn_cast<Constant>(ICmp.getOperand(1));
4425 if (!C)
4426 return nullptr;
4427
4428 // Compute the constant that would happen if we truncated to SrcTy then
4429 // re-extended to DestTy.
4430 Type *SrcTy = CastOp0->getSrcTy();
4431 Type *DestTy = CastOp0->getDestTy();
4432 Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy);
4433 Constant *Res2 = ConstantExpr::getCast(CastOp0->getOpcode(), Res1, DestTy);
4434
4435 // If the re-extended constant didn't change...
4436 if (Res2 == C) {
4437 if (ICmp.isEquality())
4438 return new ICmpInst(ICmp.getPredicate(), X, Res1);
4439
4440 // A signed comparison of sign extended values simplifies into a
4441 // signed comparison.
4442 if (IsSignedExt && IsSignedCmp)
4443 return new ICmpInst(ICmp.getPredicate(), X, Res1);
4444
4445 // The other three cases all fold into an unsigned comparison.
4446 return new ICmpInst(ICmp.getUnsignedPredicate(), X, Res1);
4447 }
4448
4449 // The re-extended constant changed, partly changed (in the case of a vector),
4450 // or could not be determined to be equal (in the case of a constant
4451 // expression), so the constant cannot be represented in the shorter type.
4452 // All the cases that fold to true or false will have already been handled
4453 // by SimplifyICmpInst, so only deal with the tricky case.
4454 if (IsSignedCmp || !IsSignedExt || !isa<ConstantInt>(C))
4455 return nullptr;
4456
4457 // Is source op positive?
4458 // icmp ult (sext X), C --> icmp sgt X, -1
4459 if (ICmp.getPredicate() == ICmpInst::ICMP_ULT)
4460 return new ICmpInst(CmpInst::ICMP_SGT, X, Constant::getAllOnesValue(SrcTy));
4461
4462 // Is source op negative?
4463 // icmp ugt (sext X), C --> icmp slt X, 0
4464 assert(ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!")((ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!"
) ? static_cast<void> (0) : __assert_fail ("ICmp.getPredicate() == ICmpInst::ICMP_UGT && \"ICmp should be folded!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4464, __PRETTY_FUNCTION__))
;
4465 return new ICmpInst(CmpInst::ICMP_SLT, X, Constant::getNullValue(SrcTy));
4466}
4467
4468/// Handle icmp (cast x), (cast or constant).
4469Instruction *InstCombinerImpl::foldICmpWithCastOp(ICmpInst &ICmp) {
4470 auto *CastOp0 = dyn_cast<CastInst>(ICmp.getOperand(0));
4471 if (!CastOp0)
4472 return nullptr;
4473 if (!isa<Constant>(ICmp.getOperand(1)) && !isa<CastInst>(ICmp.getOperand(1)))
4474 return nullptr;
4475
4476 Value *Op0Src = CastOp0->getOperand(0);
4477 Type *SrcTy = CastOp0->getSrcTy();
4478 Type *DestTy = CastOp0->getDestTy();
4479
4480 // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
4481 // integer type is the same size as the pointer type.
4482 auto CompatibleSizes = [&](Type *SrcTy, Type *DestTy) {
4483 if (isa<VectorType>(SrcTy)) {
4484 SrcTy = cast<VectorType>(SrcTy)->getElementType();
4485 DestTy = cast<VectorType>(DestTy)->getElementType();
4486 }
4487 return DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth();
4488 };
4489 if (CastOp0->getOpcode() == Instruction::PtrToInt &&
4490 CompatibleSizes(SrcTy, DestTy)) {
4491 Value *NewOp1 = nullptr;
4492 if (auto *PtrToIntOp1 = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) {
4493 Value *PtrSrc = PtrToIntOp1->getOperand(0);
4494 if (PtrSrc->getType()->getPointerAddressSpace() ==
4495 Op0Src->getType()->getPointerAddressSpace()) {
4496 NewOp1 = PtrToIntOp1->getOperand(0);
4497 // If the pointer types don't match, insert a bitcast.
4498 if (Op0Src->getType() != NewOp1->getType())
4499 NewOp1 = Builder.CreateBitCast(NewOp1, Op0Src->getType());
4500 }
4501 } else if (auto *RHSC = dyn_cast<Constant>(ICmp.getOperand(1))) {
4502 NewOp1 = ConstantExpr::getIntToPtr(RHSC, SrcTy);
4503 }
4504
4505 if (NewOp1)
4506 return new ICmpInst(ICmp.getPredicate(), Op0Src, NewOp1);
4507 }
4508
4509 return foldICmpWithZextOrSext(ICmp, Builder);
4510}
4511
4512static bool isNeutralValue(Instruction::BinaryOps BinaryOp, Value *RHS) {
4513 switch (BinaryOp) {
4514 default:
4515 llvm_unreachable("Unsupported binary op")::llvm::llvm_unreachable_internal("Unsupported binary op", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4515)
;
4516 case Instruction::Add:
4517 case Instruction::Sub:
4518 return match(RHS, m_Zero());
4519 case Instruction::Mul:
4520 return match(RHS, m_One());
4521 }
4522}
4523
4524OverflowResult
4525InstCombinerImpl::computeOverflow(Instruction::BinaryOps BinaryOp,
4526 bool IsSigned, Value *LHS, Value *RHS,
4527 Instruction *CxtI) const {
4528 switch (BinaryOp) {
4529 default:
4530 llvm_unreachable("Unsupported binary op")::llvm::llvm_unreachable_internal("Unsupported binary op", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4530)
;
4531 case Instruction::Add:
4532 if (IsSigned)
4533 return computeOverflowForSignedAdd(LHS, RHS, CxtI);
4534 else
4535 return computeOverflowForUnsignedAdd(LHS, RHS, CxtI);
4536 case Instruction::Sub:
4537 if (IsSigned)
4538 return computeOverflowForSignedSub(LHS, RHS, CxtI);
4539 else
4540 return computeOverflowForUnsignedSub(LHS, RHS, CxtI);
4541 case Instruction::Mul:
4542 if (IsSigned)
4543 return computeOverflowForSignedMul(LHS, RHS, CxtI);
4544 else
4545 return computeOverflowForUnsignedMul(LHS, RHS, CxtI);
4546 }
4547}
4548
4549bool InstCombinerImpl::OptimizeOverflowCheck(Instruction::BinaryOps BinaryOp,
4550 bool IsSigned, Value *LHS,
4551 Value *RHS, Instruction &OrigI,
4552 Value *&Result,
4553 Constant *&Overflow) {
4554 if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS))
4555 std::swap(LHS, RHS);
4556
4557 // If the overflow check was an add followed by a compare, the insertion point
4558 // may be pointing to the compare. We want to insert the new instructions
4559 // before the add in case there are uses of the add between the add and the
4560 // compare.
4561 Builder.SetInsertPoint(&OrigI);
4562
4563 Type *OverflowTy = Type::getInt1Ty(LHS->getContext());
4564 if (auto *LHSTy = dyn_cast<VectorType>(LHS->getType()))
4565 OverflowTy = VectorType::get(OverflowTy, LHSTy->getElementCount());
4566
4567 if (isNeutralValue(BinaryOp, RHS)) {
4568 Result = LHS;
4569 Overflow = ConstantInt::getFalse(OverflowTy);
4570 return true;
4571 }
4572
4573 switch (computeOverflow(BinaryOp, IsSigned, LHS, RHS, &OrigI)) {
4574 case OverflowResult::MayOverflow:
4575 return false;
4576 case OverflowResult::AlwaysOverflowsLow:
4577 case OverflowResult::AlwaysOverflowsHigh:
4578 Result = Builder.CreateBinOp(BinaryOp, LHS, RHS);
4579 Result->takeName(&OrigI);
4580 Overflow = ConstantInt::getTrue(OverflowTy);
4581 return true;
4582 case OverflowResult::NeverOverflows:
4583 Result = Builder.CreateBinOp(BinaryOp, LHS, RHS);
4584 Result->takeName(&OrigI);
4585 Overflow = ConstantInt::getFalse(OverflowTy);
4586 if (auto *Inst = dyn_cast<Instruction>(Result)) {
4587 if (IsSigned)
4588 Inst->setHasNoSignedWrap();
4589 else
4590 Inst->setHasNoUnsignedWrap();
4591 }
4592 return true;
4593 }
4594
4595 llvm_unreachable("Unexpected overflow result")::llvm::llvm_unreachable_internal("Unexpected overflow result"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4595)
;
4596}
4597
4598/// Recognize and process idiom involving test for multiplication
4599/// overflow.
4600///
4601/// The caller has matched a pattern of the form:
4602/// I = cmp u (mul(zext A, zext B), V
4603/// The function checks if this is a test for overflow and if so replaces
4604/// multiplication with call to 'mul.with.overflow' intrinsic.
4605///
4606/// \param I Compare instruction.
4607/// \param MulVal Result of 'mult' instruction. It is one of the arguments of
4608/// the compare instruction. Must be of integer type.
4609/// \param OtherVal The other argument of compare instruction.
4610/// \returns Instruction which must replace the compare instruction, NULL if no
4611/// replacement required.
4612static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal,
4613 Value *OtherVal,
4614 InstCombinerImpl &IC) {
4615 // Don't bother doing this transformation for pointers, don't do it for
4616 // vectors.
4617 if (!isa<IntegerType>(MulVal->getType()))
4618 return nullptr;
4619
4620 assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal)((I.getOperand(0) == MulVal || I.getOperand(1) == MulVal) ? static_cast
<void> (0) : __assert_fail ("I.getOperand(0) == MulVal || I.getOperand(1) == MulVal"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4620, __PRETTY_FUNCTION__))
;
4621 assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal)((I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal)
? static_cast<void> (0) : __assert_fail ("I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4621, __PRETTY_FUNCTION__))
;
4622 auto *MulInstr = dyn_cast<Instruction>(MulVal);
4623 if (!MulInstr)
4624 return nullptr;
4625 assert(MulInstr->getOpcode() == Instruction::Mul)((MulInstr->getOpcode() == Instruction::Mul) ? static_cast
<void> (0) : __assert_fail ("MulInstr->getOpcode() == Instruction::Mul"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4625, __PRETTY_FUNCTION__))
;
4626
4627 auto *LHS = cast<ZExtOperator>(MulInstr->getOperand(0)),
4628 *RHS = cast<ZExtOperator>(MulInstr->getOperand(1));
4629 assert(LHS->getOpcode() == Instruction::ZExt)((LHS->getOpcode() == Instruction::ZExt) ? static_cast<
void> (0) : __assert_fail ("LHS->getOpcode() == Instruction::ZExt"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4629, __PRETTY_FUNCTION__))
;
4630 assert(RHS->getOpcode() == Instruction::ZExt)((RHS->getOpcode() == Instruction::ZExt) ? static_cast<
void> (0) : __assert_fail ("RHS->getOpcode() == Instruction::ZExt"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4630, __PRETTY_FUNCTION__))
;
4631 Value *A = LHS->getOperand(0), *B = RHS->getOperand(0);
4632
4633 // Calculate type and width of the result produced by mul.with.overflow.
4634 Type *TyA = A->getType(), *TyB = B->getType();
4635 unsigned WidthA = TyA->getPrimitiveSizeInBits(),
4636 WidthB = TyB->getPrimitiveSizeInBits();
4637 unsigned MulWidth;
4638 Type *MulType;
4639 if (WidthB > WidthA) {
4640 MulWidth = WidthB;
4641 MulType = TyB;
4642 } else {
4643 MulWidth = WidthA;
4644 MulType = TyA;
4645 }
4646
4647 // In order to replace the original mul with a narrower mul.with.overflow,
4648 // all uses must ignore upper bits of the product. The number of used low
4649 // bits must be not greater than the width of mul.with.overflow.
4650 if (MulVal->hasNUsesOrMore(2))
4651 for (User *U : MulVal->users()) {
4652 if (U == &I)
4653 continue;
4654 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
4655 // Check if truncation ignores bits above MulWidth.
4656 unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits();
4657 if (TruncWidth > MulWidth)
4658 return nullptr;
4659 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
4660 // Check if AND ignores bits above MulWidth.
4661 if (BO->getOpcode() != Instruction::And)
4662 return nullptr;
4663 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->getOperand(1))) {
4664 const APInt &CVal = CI->getValue();
4665 if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth)
4666 return nullptr;
4667 } else {
4668 // In this case we could have the operand of the binary operation
4669 // being defined in another block, and performing the replacement
4670 // could break the dominance relation.
4671 return nullptr;
4672 }
4673 } else {
4674 // Other uses prohibit this transformation.
4675 return nullptr;
4676 }
4677 }
4678
4679 // Recognize patterns
4680 switch (I.getPredicate()) {
4681 case ICmpInst::ICMP_EQ:
4682 case ICmpInst::ICMP_NE:
4683 // Recognize pattern:
4684 // mulval = mul(zext A, zext B)
4685 // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits.
4686 ConstantInt *CI;
4687 Value *ValToMask;
4688 if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) {
4689 if (ValToMask != MulVal)
4690 return nullptr;
4691 const APInt &CVal = CI->getValue() + 1;
4692 if (CVal.isPowerOf2()) {
4693 unsigned MaskWidth = CVal.logBase2();
4694 if (MaskWidth == MulWidth)
4695 break; // Recognized
4696 }
4697 }
4698 return nullptr;
4699
4700 case ICmpInst::ICMP_UGT:
4701 // Recognize pattern:
4702 // mulval = mul(zext A, zext B)
4703 // cmp ugt mulval, max
4704 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
4705 APInt MaxVal = APInt::getMaxValue(MulWidth);
4706 MaxVal = MaxVal.zext(CI->getBitWidth());
4707 if (MaxVal.eq(CI->getValue()))
4708 break; // Recognized
4709 }
4710 return nullptr;
4711
4712 case ICmpInst::ICMP_UGE:
4713 // Recognize pattern:
4714 // mulval = mul(zext A, zext B)
4715 // cmp uge mulval, max+1
4716 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
4717 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
4718 if (MaxVal.eq(CI->getValue()))
4719 break; // Recognized
4720 }
4721 return nullptr;
4722
4723 case ICmpInst::ICMP_ULE:
4724 // Recognize pattern:
4725 // mulval = mul(zext A, zext B)
4726 // cmp ule mulval, max
4727 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
4728 APInt MaxVal = APInt::getMaxValue(MulWidth);
4729 MaxVal = MaxVal.zext(CI->getBitWidth());
4730 if (MaxVal.eq(CI->getValue()))
4731 break; // Recognized
4732 }
4733 return nullptr;
4734
4735 case ICmpInst::ICMP_ULT:
4736 // Recognize pattern:
4737 // mulval = mul(zext A, zext B)
4738 // cmp ule mulval, max + 1
4739 if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) {
4740 APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth);
4741 if (MaxVal.eq(CI->getValue()))
4742 break; // Recognized
4743 }
4744 return nullptr;
4745
4746 default:
4747 return nullptr;
4748 }
4749
4750 InstCombiner::BuilderTy &Builder = IC.Builder;
4751 Builder.SetInsertPoint(MulInstr);
4752
4753 // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B)
4754 Value *MulA = A, *MulB = B;
4755 if (WidthA < MulWidth)
4756 MulA = Builder.CreateZExt(A, MulType);
4757 if (WidthB < MulWidth)
4758 MulB = Builder.CreateZExt(B, MulType);
4759 Function *F = Intrinsic::getDeclaration(
4760 I.getModule(), Intrinsic::umul_with_overflow, MulType);
4761 CallInst *Call = Builder.CreateCall(F, {MulA, MulB}, "umul");
4762 IC.addToWorklist(MulInstr);
4763
4764 // If there are uses of mul result other than the comparison, we know that
4765 // they are truncation or binary AND. Change them to use result of
4766 // mul.with.overflow and adjust properly mask/size.
4767 if (MulVal->hasNUsesOrMore(2)) {
4768 Value *Mul = Builder.CreateExtractValue(Call, 0, "umul.value");
4769 for (User *U : make_early_inc_range(MulVal->users())) {
4770 if (U == &I || U == OtherVal)
4771 continue;
4772 if (TruncInst *TI = dyn_cast<TruncInst>(U)) {
4773 if (TI->getType()->getPrimitiveSizeInBits() == MulWidth)
4774 IC.replaceInstUsesWith(*TI, Mul);
4775 else
4776 TI->setOperand(0, Mul);
4777 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U)) {
4778 assert(BO->getOpcode() == Instruction::And)((BO->getOpcode() == Instruction::And) ? static_cast<void
> (0) : __assert_fail ("BO->getOpcode() == Instruction::And"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4778, __PRETTY_FUNCTION__))
;
4779 // Replace (mul & mask) --> zext (mul.with.overflow & short_mask)
4780 ConstantInt *CI = cast<ConstantInt>(BO->getOperand(1));
4781 APInt ShortMask = CI->getValue().trunc(MulWidth);
4782 Value *ShortAnd = Builder.CreateAnd(Mul, ShortMask);
4783 Value *Zext = Builder.CreateZExt(ShortAnd, BO->getType());
4784 IC.replaceInstUsesWith(*BO, Zext);
4785 } else {
4786 llvm_unreachable("Unexpected Binary operation")::llvm::llvm_unreachable_internal("Unexpected Binary operation"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4786)
;
4787 }
4788 IC.addToWorklist(cast<Instruction>(U));
4789 }
4790 }
4791 if (isa<Instruction>(OtherVal))
4792 IC.addToWorklist(cast<Instruction>(OtherVal));
4793
4794 // The original icmp gets replaced with the overflow value, maybe inverted
4795 // depending on predicate.
4796 bool Inverse = false;
4797 switch (I.getPredicate()) {
4798 case ICmpInst::ICMP_NE:
4799 break;
4800 case ICmpInst::ICMP_EQ:
4801 Inverse = true;
4802 break;
4803 case ICmpInst::ICMP_UGT:
4804 case ICmpInst::ICMP_UGE:
4805 if (I.getOperand(0) == MulVal)
4806 break;
4807 Inverse = true;
4808 break;
4809 case ICmpInst::ICMP_ULT:
4810 case ICmpInst::ICMP_ULE:
4811 if (I.getOperand(1) == MulVal)
4812 break;
4813 Inverse = true;
4814 break;
4815 default:
4816 llvm_unreachable("Unexpected predicate")::llvm::llvm_unreachable_internal("Unexpected predicate", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4816)
;
4817 }
4818 if (Inverse) {
4819 Value *Res = Builder.CreateExtractValue(Call, 1);
4820 return BinaryOperator::CreateNot(Res);
4821 }
4822
4823 return ExtractValueInst::Create(Call, 1);
4824}
4825
4826/// When performing a comparison against a constant, it is possible that not all
4827/// the bits in the LHS are demanded. This helper method computes the mask that
4828/// IS demanded.
4829static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth) {
4830 const APInt *RHS;
4831 if (!match(I.getOperand(1), m_APInt(RHS)))
4832 return APInt::getAllOnesValue(BitWidth);
4833
4834 // If this is a normal comparison, it demands all bits. If it is a sign bit
4835 // comparison, it only demands the sign bit.
4836 bool UnusedBit;
4837 if (InstCombiner::isSignBitCheck(I.getPredicate(), *RHS, UnusedBit))
4838 return APInt::getSignMask(BitWidth);
4839
4840 switch (I.getPredicate()) {
4841 // For a UGT comparison, we don't care about any bits that
4842 // correspond to the trailing ones of the comparand. The value of these
4843 // bits doesn't impact the outcome of the comparison, because any value
4844 // greater than the RHS must differ in a bit higher than these due to carry.
4845 case ICmpInst::ICMP_UGT:
4846 return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingOnes());
4847
4848 // Similarly, for a ULT comparison, we don't care about the trailing zeros.
4849 // Any value less than the RHS must differ in a higher bit because of carries.
4850 case ICmpInst::ICMP_ULT:
4851 return APInt::getBitsSetFrom(BitWidth, RHS->countTrailingZeros());
4852
4853 default:
4854 return APInt::getAllOnesValue(BitWidth);
4855 }
4856}
4857
4858/// Check if the order of \p Op0 and \p Op1 as operands in an ICmpInst
4859/// should be swapped.
4860/// The decision is based on how many times these two operands are reused
4861/// as subtract operands and their positions in those instructions.
4862/// The rationale is that several architectures use the same instruction for
4863/// both subtract and cmp. Thus, it is better if the order of those operands
4864/// match.
4865/// \return true if Op0 and Op1 should be swapped.
4866static bool swapMayExposeCSEOpportunities(const Value *Op0, const Value *Op1) {
4867 // Filter out pointer values as those cannot appear directly in subtract.
4868 // FIXME: we may want to go through inttoptrs or bitcasts.
4869 if (Op0->getType()->isPointerTy())
4870 return false;
4871 // If a subtract already has the same operands as a compare, swapping would be
4872 // bad. If a subtract has the same operands as a compare but in reverse order,
4873 // then swapping is good.
4874 int GoodToSwap = 0;
4875 for (const User *U : Op0->users()) {
4876 if (match(U, m_Sub(m_Specific(Op1), m_Specific(Op0))))
4877 GoodToSwap++;
4878 else if (match(U, m_Sub(m_Specific(Op0), m_Specific(Op1))))
4879 GoodToSwap--;
4880 }
4881 return GoodToSwap > 0;
4882}
4883
4884/// Check that one use is in the same block as the definition and all
4885/// other uses are in blocks dominated by a given block.
4886///
4887/// \param DI Definition
4888/// \param UI Use
4889/// \param DB Block that must dominate all uses of \p DI outside
4890/// the parent block
4891/// \return true when \p UI is the only use of \p DI in the parent block
4892/// and all other uses of \p DI are in blocks dominated by \p DB.
4893///
4894bool InstCombinerImpl::dominatesAllUses(const Instruction *DI,
4895 const Instruction *UI,
4896 const BasicBlock *DB) const {
4897 assert(DI && UI && "Instruction not defined\n")((DI && UI && "Instruction not defined\n") ? static_cast
<void> (0) : __assert_fail ("DI && UI && \"Instruction not defined\\n\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4897, __PRETTY_FUNCTION__))
;
4898 // Ignore incomplete definitions.
4899 if (!DI->getParent())
4900 return false;
4901 // DI and UI must be in the same block.
4902 if (DI->getParent() != UI->getParent())
4903 return false;
4904 // Protect from self-referencing blocks.
4905 if (DI->getParent() == DB)
4906 return false;
4907 for (const User *U : DI->users()) {
4908 auto *Usr = cast<Instruction>(U);
4909 if (Usr != UI && !DT.dominates(DB, Usr->getParent()))
4910 return false;
4911 }
4912 return true;
4913}
4914
4915/// Return true when the instruction sequence within a block is select-cmp-br.
4916static bool isChainSelectCmpBranch(const SelectInst *SI) {
4917 const BasicBlock *BB = SI->getParent();
4918 if (!BB)
4919 return false;
4920 auto *BI = dyn_cast_or_null<BranchInst>(BB->getTerminator());
4921 if (!BI || BI->getNumSuccessors() != 2)
4922 return false;
4923 auto *IC = dyn_cast<ICmpInst>(BI->getCondition());
4924 if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI))
4925 return false;
4926 return true;
4927}
4928
4929/// True when a select result is replaced by one of its operands
4930/// in select-icmp sequence. This will eventually result in the elimination
4931/// of the select.
4932///
4933/// \param SI Select instruction
4934/// \param Icmp Compare instruction
4935/// \param SIOpd Operand that replaces the select
4936///
4937/// Notes:
4938/// - The replacement is global and requires dominator information
4939/// - The caller is responsible for the actual replacement
4940///
4941/// Example:
4942///
4943/// entry:
4944/// %4 = select i1 %3, %C* %0, %C* null
4945/// %5 = icmp eq %C* %4, null
4946/// br i1 %5, label %9, label %7
4947/// ...
4948/// ; <label>:7 ; preds = %entry
4949/// %8 = getelementptr inbounds %C* %4, i64 0, i32 0
4950/// ...
4951///
4952/// can be transformed to
4953///
4954/// %5 = icmp eq %C* %0, null
4955/// %6 = select i1 %3, i1 %5, i1 true
4956/// br i1 %6, label %9, label %7
4957/// ...
4958/// ; <label>:7 ; preds = %entry
4959/// %8 = getelementptr inbounds %C* %0, i64 0, i32 0 // replace by %0!
4960///
4961/// Similar when the first operand of the select is a constant or/and
4962/// the compare is for not equal rather than equal.
4963///
4964/// NOTE: The function is only called when the select and compare constants
4965/// are equal, the optimization can work only for EQ predicates. This is not a
4966/// major restriction since a NE compare should be 'normalized' to an equal
4967/// compare, which usually happens in the combiner and test case
4968/// select-cmp-br.ll checks for it.
4969bool InstCombinerImpl::replacedSelectWithOperand(SelectInst *SI,
4970 const ICmpInst *Icmp,
4971 const unsigned SIOpd) {
4972 assert((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!")(((SIOpd == 1 || SIOpd == 2) && "Invalid select operand!"
) ? static_cast<void> (0) : __assert_fail ("(SIOpd == 1 || SIOpd == 2) && \"Invalid select operand!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 4972, __PRETTY_FUNCTION__))
;
4973 if (isChainSelectCmpBranch(SI) && Icmp->getPredicate() == ICmpInst::ICMP_EQ) {
4974 BasicBlock *Succ = SI->getParent()->getTerminator()->getSuccessor(1);
4975 // The check for the single predecessor is not the best that can be
4976 // done. But it protects efficiently against cases like when SI's
4977 // home block has two successors, Succ and Succ1, and Succ1 predecessor
4978 // of Succ. Then SI can't be replaced by SIOpd because the use that gets
4979 // replaced can be reached on either path. So the uniqueness check
4980 // guarantees that the path all uses of SI (outside SI's parent) are on
4981 // is disjoint from all other paths out of SI. But that information
4982 // is more expensive to compute, and the trade-off here is in favor
4983 // of compile-time. It should also be noticed that we check for a single
4984 // predecessor and not only uniqueness. This to handle the situation when
4985 // Succ and Succ1 points to the same basic block.
4986 if (Succ->getSinglePredecessor() && dominatesAllUses(SI, Icmp, Succ)) {
4987 NumSel++;
4988 SI->replaceUsesOutsideBlock(SI->getOperand(SIOpd), SI->getParent());
4989 return true;
4990 }
4991 }
4992 return false;
4993}
4994
4995/// Try to fold the comparison based on range information we can get by checking
4996/// whether bits are known to be zero or one in the inputs.
4997Instruction *InstCombinerImpl::foldICmpUsingKnownBits(ICmpInst &I) {
4998 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
4999 Type *Ty = Op0->getType();
5000 ICmpInst::Predicate Pred = I.getPredicate();
5001
5002 // Get scalar or pointer size.
5003 unsigned BitWidth = Ty->isIntOrIntVectorTy()
5004 ? Ty->getScalarSizeInBits()
5005 : DL.getPointerTypeSizeInBits(Ty->getScalarType());
5006
5007 if (!BitWidth)
5008 return nullptr;
5009
5010 KnownBits Op0Known(BitWidth);
5011 KnownBits Op1Known(BitWidth);
5012
5013 if (SimplifyDemandedBits(&I, 0,
5014 getDemandedBitsLHSMask(I, BitWidth),
5015 Op0Known, 0))
5016 return &I;
5017
5018 if (SimplifyDemandedBits(&I, 1, APInt::getAllOnesValue(BitWidth),
5019 Op1Known, 0))
5020 return &I;
5021
5022 // Given the known and unknown bits, compute a range that the LHS could be
5023 // in. Compute the Min, Max and RHS values based on the known bits. For the
5024 // EQ and NE we use unsigned values.
5025 APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
5026 APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
5027 if (I.isSigned()) {
5028 Op0Min = Op0Known.getSignedMinValue();
5029 Op0Max = Op0Known.getSignedMaxValue();
5030 Op1Min = Op1Known.getSignedMinValue();
5031 Op1Max = Op1Known.getSignedMaxValue();
5032 } else {
5033 Op0Min = Op0Known.getMinValue();
5034 Op0Max = Op0Known.getMaxValue();
5035 Op1Min = Op1Known.getMinValue();
5036 Op1Max = Op1Known.getMaxValue();
5037 }
5038
5039 // If Min and Max are known to be the same, then SimplifyDemandedBits figured
5040 // out that the LHS or RHS is a constant. Constant fold this now, so that
5041 // code below can assume that Min != Max.
5042 if (!isa<Constant>(Op0) && Op0Min == Op0Max)
5043 return new ICmpInst(Pred, ConstantExpr::getIntegerValue(Ty, Op0Min), Op1);
5044 if (!isa<Constant>(Op1) && Op1Min == Op1Max)
5045 return new ICmpInst(Pred, Op0, ConstantExpr::getIntegerValue(Ty, Op1Min));
5046
5047 // Based on the range information we know about the LHS, see if we can
5048 // simplify this comparison. For example, (x&4) < 8 is always true.
5049 switch (Pred) {
5050 default:
5051 llvm_unreachable("Unknown icmp opcode!")::llvm::llvm_unreachable_internal("Unknown icmp opcode!", "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5051)
;
5052 case ICmpInst::ICMP_EQ:
5053 case ICmpInst::ICMP_NE: {
5054 if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
5055 return replaceInstUsesWith(
5056 I, ConstantInt::getBool(I.getType(), Pred == CmpInst::ICMP_NE));
5057
5058 // If all bits are known zero except for one, then we know at most one bit
5059 // is set. If the comparison is against zero, then this is a check to see if
5060 // *that* bit is set.
5061 APInt Op0KnownZeroInverted = ~Op0Known.Zero;
5062 if (Op1Known.isZero()) {
5063 // If the LHS is an AND with the same constant, look through it.
5064 Value *LHS = nullptr;
5065 const APInt *LHSC;
5066 if (!match(Op0, m_And(m_Value(LHS), m_APInt(LHSC))) ||
5067 *LHSC != Op0KnownZeroInverted)
5068 LHS = Op0;
5069
5070 Value *X;
5071 if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
5072 APInt ValToCheck = Op0KnownZeroInverted;
5073 Type *XTy = X->getType();
5074 if (ValToCheck.isPowerOf2()) {
5075 // ((1 << X) & 8) == 0 -> X != 3
5076 // ((1 << X) & 8) != 0 -> X == 3
5077 auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
5078 auto NewPred = ICmpInst::getInversePredicate(Pred);
5079 return new ICmpInst(NewPred, X, CmpC);
5080 } else if ((++ValToCheck).isPowerOf2()) {
5081 // ((1 << X) & 7) == 0 -> X >= 3
5082 // ((1 << X) & 7) != 0 -> X < 3
5083 auto *CmpC = ConstantInt::get(XTy, ValToCheck.countTrailingZeros());
5084 auto NewPred =
5085 Pred == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGE : CmpInst::ICMP_ULT;
5086 return new ICmpInst(NewPred, X, CmpC);
5087 }
5088 }
5089
5090 // Check if the LHS is 8 >>u x and the result is a power of 2 like 1.
5091 const APInt *CI;
5092 if (Op0KnownZeroInverted.isOneValue() &&
5093 match(LHS, m_LShr(m_Power2(CI), m_Value(X)))) {
5094 // ((8 >>u X) & 1) == 0 -> X != 3
5095 // ((8 >>u X) & 1) != 0 -> X == 3
5096 unsigned CmpVal = CI->countTrailingZeros();
5097 auto NewPred = ICmpInst::getInversePredicate(Pred);
5098 return new ICmpInst(NewPred, X, ConstantInt::get(X->getType(), CmpVal));
5099 }
5100 }
5101 break;
5102 }
5103 case ICmpInst::ICMP_ULT: {
5104 if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
5105 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5106 if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
5107 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5108 if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
5109 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5110
5111 const APInt *CmpC;
5112 if (match(Op1, m_APInt(CmpC))) {
5113 // A <u C -> A == C-1 if min(A)+1 == C
5114 if (*CmpC == Op0Min + 1)
5115 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
5116 ConstantInt::get(Op1->getType(), *CmpC - 1));
5117 // X <u C --> X == 0, if the number of zero bits in the bottom of X
5118 // exceeds the log2 of C.
5119 if (Op0Known.countMinTrailingZeros() >= CmpC->ceilLogBase2())
5120 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
5121 Constant::getNullValue(Op1->getType()));
5122 }
5123 break;
5124 }
5125 case ICmpInst::ICMP_UGT: {
5126 if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
5127 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5128 if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
5129 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5130 if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
5131 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5132
5133 const APInt *CmpC;
5134 if (match(Op1, m_APInt(CmpC))) {
5135 // A >u C -> A == C+1 if max(a)-1 == C
5136 if (*CmpC == Op0Max - 1)
5137 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
5138 ConstantInt::get(Op1->getType(), *CmpC + 1));
5139 // X >u C --> X != 0, if the number of zero bits in the bottom of X
5140 // exceeds the log2 of C.
5141 if (Op0Known.countMinTrailingZeros() >= CmpC->getActiveBits())
5142 return new ICmpInst(ICmpInst::ICMP_NE, Op0,
5143 Constant::getNullValue(Op1->getType()));
5144 }
5145 break;
5146 }
5147 case ICmpInst::ICMP_SLT: {
5148 if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
5149 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5150 if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
5151 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5152 if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
5153 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5154 const APInt *CmpC;
5155 if (match(Op1, m_APInt(CmpC))) {
5156 if (*CmpC == Op0Min + 1) // A <s C -> A == C-1 if min(A)+1 == C
5157 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
5158 ConstantInt::get(Op1->getType(), *CmpC - 1));
5159 }
5160 break;
5161 }
5162 case ICmpInst::ICMP_SGT: {
5163 if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
5164 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5165 if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
5166 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5167 if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
5168 return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
5169 const APInt *CmpC;
5170 if (match(Op1, m_APInt(CmpC))) {
5171 if (*CmpC == Op0Max - 1) // A >s C -> A == C+1 if max(A)-1 == C
5172 return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
5173 ConstantInt::get(Op1->getType(), *CmpC + 1));
5174 }
5175 break;
5176 }
5177 case ICmpInst::ICMP_SGE:
5178 assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_SGE with ConstantInt not folded!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5178, __PRETTY_FUNCTION__))
;
5179 if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
5180 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5181 if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
5182 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5183 if (Op1Min == Op0Max) // A >=s B -> A == B if max(A) == min(B)
5184 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5185 break;
5186 case ICmpInst::ICMP_SLE:
5187 assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_SLE with ConstantInt not folded!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5187, __PRETTY_FUNCTION__))
;
5188 if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
5189 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5190 if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
5191 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5192 if (Op1Max == Op0Min) // A <=s B -> A == B if min(A) == max(B)
5193 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5194 break;
5195 case ICmpInst::ICMP_UGE:
5196 assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_UGE with ConstantInt not folded!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5196, __PRETTY_FUNCTION__))
;
5197 if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
5198 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5199 if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
5200 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5201 if (Op1Min == Op0Max) // A >=u B -> A == B if max(A) == min(B)
5202 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5203 break;
5204 case ICmpInst::ICMP_ULE:
5205 assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!")((!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!"
) ? static_cast<void> (0) : __assert_fail ("!isa<ConstantInt>(Op1) && \"ICMP_ULE with ConstantInt not folded!\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5205, __PRETTY_FUNCTION__))
;
5206 if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
5207 return replaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
5208 if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
5209 return replaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
5210 if (Op1Max == Op0Min) // A <=u B -> A == B if min(A) == max(B)
5211 return new ICmpInst(ICmpInst::ICMP_EQ, Op0, Op1);
5212 break;
5213 }
5214
5215 // Turn a signed comparison into an unsigned one if both operands are known to
5216 // have the same sign.
5217 if (I.isSigned() &&
5218 ((Op0Known.Zero.isNegative() && Op1Known.Zero.isNegative()) ||
5219 (Op0Known.One.isNegative() && Op1Known.One.isNegative())))
5220 return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
5221
5222 return nullptr;
5223}
5224
5225llvm::Optional<std::pair<CmpInst::Predicate, Constant *>>
5226InstCombiner::getFlippedStrictnessPredicateAndConstant(CmpInst::Predicate Pred,
5227 Constant *C) {
5228 assert(ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) &&((ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate
(Pred) && "Only for relational integer predicates.") ?
static_cast<void> (0) : __assert_fail ("ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) && \"Only for relational integer predicates.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5229, __PRETTY_FUNCTION__))
5229 "Only for relational integer predicates.")((ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate
(Pred) && "Only for relational integer predicates.") ?
static_cast<void> (0) : __assert_fail ("ICmpInst::isRelational(Pred) && ICmpInst::isIntPredicate(Pred) && \"Only for relational integer predicates.\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5229, __PRETTY_FUNCTION__))
;
5230
5231 Type *Type = C->getType();
5232 bool IsSigned = ICmpInst::isSigned(Pred);
5233
5234 CmpInst::Predicate UnsignedPred = ICmpInst::getUnsignedPredicate(Pred);
5235 bool WillIncrement =
5236 UnsignedPred == ICmpInst::ICMP_ULE || UnsignedPred == ICmpInst::ICMP_UGT;
5237
5238 // Check if the constant operand can be safely incremented/decremented
5239 // without overflowing/underflowing.
5240 auto ConstantIsOk = [WillIncrement, IsSigned](ConstantInt *C) {
5241 return WillIncrement ? !C->isMaxValue(IsSigned) : !C->isMinValue(IsSigned);
5242 };
5243
5244 Constant *SafeReplacementConstant = nullptr;
5245 if (auto *CI = dyn_cast<ConstantInt>(C)) {
5246 // Bail out if the constant can't be safely incremented/decremented.
5247 if (!ConstantIsOk(CI))
5248 return llvm::None;
5249 } else if (auto *FVTy = dyn_cast<FixedVectorType>(Type)) {
5250 unsigned NumElts = FVTy->getNumElements();
5251 for (unsigned i = 0; i != NumElts; ++i) {
5252 Constant *Elt = C->getAggregateElement(i);
5253 if (!Elt)
5254 return llvm::None;
5255
5256 if (isa<UndefValue>(Elt))
5257 continue;
5258
5259 // Bail out if we can't determine if this constant is min/max or if we
5260 // know that this constant is min/max.
5261 auto *CI = dyn_cast<ConstantInt>(Elt);
5262 if (!CI || !ConstantIsOk(CI))
5263 return llvm::None;
5264
5265 if (!SafeReplacementConstant)
5266 SafeReplacementConstant = CI;
5267 }
5268 } else {
5269 // ConstantExpr?
5270 return llvm::None;
5271 }
5272
5273 // It may not be safe to change a compare predicate in the presence of
5274 // undefined elements, so replace those elements with the first safe constant
5275 // that we found.
5276 // TODO: in case of poison, it is safe; let's replace undefs only.
5277 if (C->containsUndefOrPoisonElement()) {
5278 assert(SafeReplacementConstant && "Replacement constant not set")((SafeReplacementConstant && "Replacement constant not set"
) ? static_cast<void> (0) : __assert_fail ("SafeReplacementConstant && \"Replacement constant not set\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5278, __PRETTY_FUNCTION__))
;
5279 C = Constant::replaceUndefsWith(C, SafeReplacementConstant);
5280 }
5281
5282 CmpInst::Predicate NewPred = CmpInst::getFlippedStrictnessPredicate(Pred);
5283
5284 // Increment or decrement the constant.
5285 Constant *OneOrNegOne = ConstantInt::get(Type, WillIncrement ? 1 : -1, true);
5286 Constant *NewC = ConstantExpr::getAdd(C, OneOrNegOne);
5287
5288 return std::make_pair(NewPred, NewC);
5289}
5290
5291/// If we have an icmp le or icmp ge instruction with a constant operand, turn
5292/// it into the appropriate icmp lt or icmp gt instruction. This transform
5293/// allows them to be folded in visitICmpInst.
5294static ICmpInst *canonicalizeCmpWithConstant(ICmpInst &I) {
5295 ICmpInst::Predicate Pred = I.getPredicate();
5296 if (ICmpInst::isEquality(Pred) || !ICmpInst::isIntPredicate(Pred) ||
5297 InstCombiner::isCanonicalPredicate(Pred))
5298 return nullptr;
5299
5300 Value *Op0 = I.getOperand(0);
5301 Value *Op1 = I.getOperand(1);
5302 auto *Op1C = dyn_cast<Constant>(Op1);
5303 if (!Op1C)
5304 return nullptr;
5305
5306 auto FlippedStrictness =
5307 InstCombiner::getFlippedStrictnessPredicateAndConstant(Pred, Op1C);
5308 if (!FlippedStrictness)
5309 return nullptr;
5310
5311 return new ICmpInst(FlippedStrictness->first, Op0, FlippedStrictness->second);
5312}
5313
5314/// If we have a comparison with a non-canonical predicate, if we can update
5315/// all the users, invert the predicate and adjust all the users.
5316CmpInst *InstCombinerImpl::canonicalizeICmpPredicate(CmpInst &I) {
5317 // Is the predicate already canonical?
5318 CmpInst::Predicate Pred = I.getPredicate();
5319 if (InstCombiner::isCanonicalPredicate(Pred))
5320 return nullptr;
5321
5322 // Can all users be adjusted to predicate inversion?
5323 if (!InstCombiner::canFreelyInvertAllUsersOf(&I, /*IgnoredUser=*/nullptr))
5324 return nullptr;
5325
5326 // Ok, we can canonicalize comparison!
5327 // Let's first invert the comparison's predicate.
5328 I.setPredicate(CmpInst::getInversePredicate(Pred));
5329 I.setName(I.getName() + ".not");
5330
5331 // And, adapt users.
5332 freelyInvertAllUsersOf(&I);
5333
5334 return &I;
5335}
5336
5337/// Integer compare with boolean values can always be turned into bitwise ops.
5338static Instruction *canonicalizeICmpBool(ICmpInst &I,
5339 InstCombiner::BuilderTy &Builder) {
5340 Value *A = I.getOperand(0), *B = I.getOperand(1);
5341 assert(A->getType()->isIntOrIntVectorTy(1) && "Bools only")((A->getType()->isIntOrIntVectorTy(1) && "Bools only"
) ? static_cast<void> (0) : __assert_fail ("A->getType()->isIntOrIntVectorTy(1) && \"Bools only\""
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5341, __PRETTY_FUNCTION__))
;
5342
5343 // A boolean compared to true/false can be simplified to Op0/true/false in
5344 // 14 out of the 20 (10 predicates * 2 constants) possible combinations.
5345 // Cases not handled by InstSimplify are always 'not' of Op0.
5346 if (match(B, m_Zero())) {
5347 switch (I.getPredicate()) {
5348 case CmpInst::ICMP_EQ: // A == 0 -> !A
5349 case CmpInst::ICMP_ULE: // A <=u 0 -> !A
5350 case CmpInst::ICMP_SGE: // A >=s 0 -> !A
5351 return BinaryOperator::CreateNot(A);
5352 default:
5353 llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected."
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5353)
;
5354 }
5355 } else if (match(B, m_One())) {
5356 switch (I.getPredicate()) {
5357 case CmpInst::ICMP_NE: // A != 1 -> !A
5358 case CmpInst::ICMP_ULT: // A <u 1 -> !A
5359 case CmpInst::ICMP_SGT: // A >s -1 -> !A
5360 return BinaryOperator::CreateNot(A);
5361 default:
5362 llvm_unreachable("ICmp i1 X, C not simplified as expected.")::llvm::llvm_unreachable_internal("ICmp i1 X, C not simplified as expected."
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5362)
;
5363 }
5364 }
5365
5366 switch (I.getPredicate()) {
5367 default:
5368 llvm_unreachable("Invalid icmp instruction!")::llvm::llvm_unreachable_internal("Invalid icmp instruction!"
, "/build/llvm-toolchain-snapshot-13~++20210405022414+5f57793c4fe4/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp"
, 5368)
;
5369 case ICmpInst::ICMP_EQ:
5370 // icmp eq i1 A, B -> ~(A ^ B)
5371 return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
5372
5373 case ICmpInst::ICMP_NE:
5374 // icmp ne i1 A, B -> A ^ B
5375 return BinaryOperator::CreateXor(A, B);
5376
5377 case ICmpInst::ICMP_UGT:
5378 // icmp ugt -> icmp ult
5379 std::swap(A, B);
5380 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5381 case ICmpInst::ICMP_ULT:
5382 // icmp ult i1 A, B -> ~A & B
5383 return BinaryOperator::CreateAnd(Builder.CreateNot(A), B);
5384
5385 case ICmpInst::ICMP_SGT:
5386 // icmp sgt -> icmp slt
5387 std::swap(A, B);
5388 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5389 case ICmpInst::ICMP_SLT:
5390 // icmp slt i1 A, B -> A & ~B
5391 return BinaryOperator::CreateAnd(Builder.CreateNot(B), A);
5392
5393 case ICmpInst::ICMP_UGE:
5394 // icmp uge -> icmp ule
5395 std::swap(A, B);
5396 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5397 case ICmpInst::ICMP_ULE:
5398 // icmp ule i1 A, B -> ~A | B
5399 return BinaryOperator::CreateOr(Builder.CreateNot(A), B);
5400
5401 case ICmpInst::ICMP_SGE:
5402 // icmp sge -> icmp sle
5403 std::swap(A, B);
5404 LLVM_FALLTHROUGH[[gnu::fallthrough]];
5405 case ICmpInst::ICMP_SLE:
5406 // icmp sle i1 A, B -> A | ~B
5407 return BinaryOperator::CreateOr(Builder.CreateNot(B), A);
5408 }
5409}
5410
5411// Transform pattern like:
5412// (1 << Y) u<= X or ~(-1 << Y) u< X or ((1 << Y)+(-1)) u< X
5413// (1 << Y) u> X or ~(-1 << Y) u>= X or ((1 << Y)+(-1)) u>= X
5414// Into:
5415// (X l>> Y) != 0
5416// (X l>> Y) == 0
5417static Instruction *foldICmpWithHighBitMask(ICmpInst &Cmp,
5418 InstCombiner::BuilderTy &Builder) {
5419 ICmpInst::Predicate Pred, NewPred;
5420 Value *X, *Y;
5421 if (match(&Cmp,
5422 m_c_ICmp(Pred, m_OneUse(m_Shl(m_One(), m_Value(Y))), m_Value(X)))) {
5423 switch (Pred) {
5424 case ICmpInst::ICMP_ULE:
5425 NewPred = ICmpInst::ICMP_NE;
5426 break;
5427 case ICmpInst::ICMP_UGT:
5428 NewPred = ICmpInst::ICMP_EQ;
5429 break;
5430 default:
5431 return nullptr;
5432 }
5433 } else if (match(&Cmp, m_c_ICmp(Pred,
5434 m_OneUse(m_CombineOr(
5435 m_Not(m_Shl(m_AllOnes(), m_Value(Y))),
5436 m_Add(m_Shl(m_One(), m_Value(Y)),
5437 m_AllOnes()))),
5438 m_Value(X)))) {
5439 // The variant with 'add' is not canonical, (the variant with 'not' is)
5440 // we only get it because it has extra uses, and can't be canonicalized,
5441
5442 switch (Pred) {
5443 case ICmpInst::ICMP_ULT:
5444 NewPred = ICmpInst::ICMP_NE;
5445 break;
5446 case ICmpInst::ICMP_UGE:
5447 NewPred = ICmpInst::ICMP_EQ;
5448 break;
5449 default:
5450 return nullptr;
5451 }
5452 } else
5453 return nullptr;
5454
5455 Value *NewX = Builder.CreateLShr(X, Y, X->getName() + ".highbits");
5456 Constant *Zero = Constant::getNullValue(NewX->getType());
5457 return CmpInst::Create(Instruction::ICmp, NewPred, NewX, Zero);
5458}
5459
5460static Instruction *foldVectorCmp(CmpInst &Cmp,
5461 InstCombiner::BuilderTy &Builder) {
5462 const CmpInst::Predicate Pred = Cmp.getPredicate();
5463 Value *LHS = Cmp.getOperand(0), *RHS = Cmp.getOperand(1);
5464 Value *V1, *V2;
5465 ArrayRef<int> M;
5466 if (!match(LHS, m_Shuffle(m_Value(V1), m_Undef(), m_Mask(M))))
5467 return nullptr;
5468
5469 // If both arguments of the cmp are shuffles that use the same mask and
5470 // shuffle within a single vector, move the shuffle after the cmp:
5471 // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M
5472 Type *V1Ty = V1->getType();
5473 if (match(RHS, m_Shuffle(m_Value(V2), m_Undef(), m_SpecificMask(M))) &&
5474 V1Ty == V2->getType() && (LHS->hasOneUse() || RHS->hasOneUse())) {
5475 Value *NewCmp = Builder.CreateCmp(Pred, V1, V2);
5476 return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), M);
5477 }
5478
5479 // Try to canonicalize compare with splatted operand and splat constant.
5480 // TODO: We could generalize this for more than splats. See/use the code in
5481 // InstCombiner::foldVectorBinop().
5482 Constant *C;
5483 if (!LHS->hasOneUse() || !match(RHS, m_Constant(C)))
5484 return nullptr;
5485
5486 // Length-changing splats are ok, so adjust the constants as needed:
5487 // cmp (shuffle V1, M), C --> shuffle (cmp V1, C'), M
5488 Constant *ScalarC = C->getSplatValue(/* AllowUndefs */ true);
5489 int MaskSplatIndex;
5490 if (ScalarC && match(M, m_SplatOrUndefMask(MaskSplatIndex))) {
5491 // We allow undefs in matching, but this transform removes those for safety.
5492 // Demanded elements analysis should be able to recover some/all of that.
5493 C = ConstantVector::getSplat(cast<VectorType>(V1Ty)->getElementCount(),
5494 ScalarC);
5495 SmallVector<int, 8> NewM(M.size(), MaskSplatIndex);
5496 Value *NewCmp = Builder.CreateCmp(Pred, V1, C);
5497 return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()),
5498 NewM);
5499 }
5500
5501 return nullptr;
5502}
5503
5504// extract(uadd.with.overflow(A, B), 0) ult A
5505// -> extract(uadd.with.overflow(A, B), 1)
5506static Instruction *foldICmpOfUAddOv(ICmpInst &I) {
5507 CmpInst::Predicate Pred = I.getPredicate();
5508 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5509
5510 Value *UAddOv;
5511 Value *A, *B;
5512 auto UAddOvResultPat = m_ExtractValue<0>(
5513 m_Intrinsic<Intrinsic::uadd_with_overflow>(m_Value(A), m_Value(B)));
5514 if (match(Op0, UAddOvResultPat) &&
5515 ((Pred == ICmpInst::ICMP_ULT && (Op1 == A || Op1 == B)) ||
5516 (Pred == ICmpInst::ICMP_EQ && match(Op1, m_ZeroInt()) &&
5517 (match(A, m_One()) || match(B, m_One()))) ||
5518 (Pred == ICmpInst::ICMP_NE && match(Op1, m_AllOnes()) &&
5519 (match(A, m_AllOnes()) || match(B, m_AllOnes())))))
5520 // extract(uadd.with.overflow(A, B), 0) < A
5521 // extract(uadd.with.overflow(A, 1), 0) == 0
5522 // extract(uadd.with.overflow(A, -1), 0) != -1
5523 UAddOv = cast<ExtractValueInst>(Op0)->getAggregateOperand();
5524 else if (match(Op1, UAddOvResultPat) &&
5525 Pred == ICmpInst::ICMP_UGT && (Op0 == A || Op0 == B))
5526 // A > extract(uadd.with.overflow(A, B), 0)
5527 UAddOv = cast<ExtractValueInst>(Op1)->getAggregateOperand();
5528 else
5529 return nullptr;
5530
5531 return ExtractValueInst::Create(UAddOv, 1);
5532}
5533
5534Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
5535 bool Changed = false;
5536 const SimplifyQuery Q = SQ.getWithInstruction(&I);
5537 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
5538 unsigned Op0Cplxity = getComplexity(Op0);
5539 unsigned Op1Cplxity = getComplexity(Op1);
5540
5541 /// Orders the operands of the compare so that they are listed from most
5542 /// complex to least complex. This puts constants before unary operators,
5543 /// before binary operators.
5544 if (Op0Cplxity < Op1Cplxity ||
5545 (Op0Cplxity == Op1Cplxity && swapMayExposeCSEOpportunities(Op0, Op1))) {
5546 I.swapOperands();
5547 std::swap(Op0, Op1);
5548 Changed = true;
5549 }
5550
5551 if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, Q))
5552 return replaceInstUsesWith(I, V);
5553
5554 // Comparing -val or val with non-zero is the same as just comparing val
5555 // ie, abs(val) != 0 -> val != 0
5556 if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) {
5557 Value *Cond, *SelectTrue, *SelectFalse;
5558 if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
5559 m_Value(SelectFalse)))) {
5560 if (Value *V = dyn_castNegVal(SelectTrue)) {
5561 if (V == SelectFalse)
5562 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
5563 }
5564 else if (Value *V = dyn_castNegVal(SelectFalse)) {
5565 if (V == SelectTrue)
5566 return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
5567 }
5568 }
5569 }
5570
5571 if (Op0->getType()->isIntOrIntVectorTy(1))
5572 if (Instruction *Res = canonicalizeICmpBool(I, Builder))
5573 return Res;
5574
5575 if (Instruction *Res = canonicalizeCmpWithConstant(I))
5576 return Res;
5577
5578 if (Instruction *Res = canonicalizeICmpPredicate(I))
5579 return Res;
5580
5581 if (Instruction *Res = foldICmpWithConstant(I))
5582 return Res;
5583
5584 if (Instruction *Res = foldICmpWithDominatingICmp(I))
5585 return Res;
5586
5587 if (Instruction *Res = foldICmpBinOp(I, Q))
5588 return Res;
5589
5590 if (Instruction *Res = foldICmpUsingKnownBits(I))
5591 return Res;
5592
5593 // Test if the ICmpInst instruction is used exclusively by a select as
5594 // part of a minimum or maximum operation. If so, refrain from doing
5595 // any other folding. This helps out other analyses which understand
5596 // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
5597 // and CodeGen. And in this case, at least one of the comparison
5598 // operands has at least one user besides the compare (the select),
5599 // which would often largely negate the benefit of folding anyway.
5600 //
5601 // Do the same for the other patterns recognized by matchSelectPattern.
5602 if (I.hasOneUse())
5603 if (SelectInst *SI = dyn_cast<SelectInst>(I.user_back())) {
5604 Value *A, *B;
5605 SelectPatternResult SPR = matchSelectPattern(SI, A, B);
5606 if (SPR.Flavor != SPF_UNKNOWN)
5607 return nullptr;
5608 }
5609
5610 // Do this after checking for min/max to prevent infinite looping.
5611 if (Instruction *Res = foldICmpWithZero(I))
5612 return Res;
5613
5614 // FIXME: We only do this after checking for min/max to prevent infinite
5615 // looping caused by a reverse canonicalization of these patterns for min/max.
5616 // FIXME: The organization of folds is a mess. These would naturally go into
5617 // canonicalizeCmpWithConstant(), but we can't move all of the above folds
5618 // down here after the min/max restriction.
5619 ICmpInst::Predicate Pred = I.getPredicate();