File: | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp |
Warning: | line 3550, column 7 Called C++ object pointer is uninitialized |
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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 | |||||||||
29 | using namespace llvm; | ||||||||
30 | using namespace PatternMatch; | ||||||||
31 | |||||||||
32 | #define DEBUG_TYPE"instcombine" "instcombine" | ||||||||
33 | |||||||||
34 | // How many times is a select replaced by one of its operands? | ||||||||
35 | STATISTIC(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. | ||||||||
40 | static 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. | ||||||||
53 | static 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. | ||||||||
66 | static 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()? | ||||||||
77 | static 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". | ||||||||
107 | Instruction * | ||||||||
108 | InstCombinerImpl::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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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 | /// | ||||||||
387 | static 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. | ||||||||
482 | static 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). | ||||||||
581 | static 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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
606 | static 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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
725 | static std::pair<Value *, Value *> | ||||||||
726 | getAsConstantIndexedAddress(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. | ||||||||
767 | static 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. | ||||||||
807 | Instruction *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 | |||||||||
987 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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". | ||||||||
1065 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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)). | ||||||||
1115 | Instruction *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-12~++20210115100614+a14c36fe27f5/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)). | ||||||||
1174 | Instruction *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-12~++20210115100614+a14c36fe27f5/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 | /// | ||||||||
1218 | static 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 | ||||||||
1306 | Instruction *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. | ||||||||
1325 | Instruction *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 | ||||||||
1356 | Instruction *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?). | ||||||||
1397 | Instruction *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. | ||||||||
1443 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
1513 | Instruction *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. | ||||||||
1546 | Instruction *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. | ||||||||
1613 | Instruction *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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
1699 | Instruction *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. | ||||||||
1807 | Instruction *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. | ||||||||
1861 | Instruction *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. | ||||||||
1927 | Instruction *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. | ||||||||
1963 | static 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. | ||||||||
2025 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
2165 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
2273 | Instruction *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. | ||||||||
2312 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
2341 | Instruction *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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
2511 | Instruction *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. | ||||||||
2573 | Instruction *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 | |||||||||
2639 | bool 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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
2692 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
2743 | static 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. | ||||||||
2868 | Instruction *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. | ||||||||
2953 | Instruction *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. | ||||||||
3058 | Instruction *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. | ||||||||
3138 | Instruction *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. | ||||||||
3208 | Instruction *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. | ||||||||
3318 | static 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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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 | ||||||||
3411 | static Value * | ||||||||
3412 | foldICmpWithTruncSignExtendedVal(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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
3485 | static Value * | ||||||||
3486 | foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ, | ||||||||
3487 | InstCombiner::BuilderTy &Builder) { | ||||||||
3488 | if (!I.isEquality() || !match(I.getOperand(1), m_Zero()) || | ||||||||
3489 | !I.getOperand(0)->hasOneUse()) | ||||||||
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( | ||||||||
| |||||||||
| |||||||||
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-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3515, __PRETTY_FUNCTION__)) | ||||||||
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-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 3515, __PRETTY_FUNCTION__)); | ||||||||
3516 | bool HadTrunc = WidestTy != I.getOperand(0)->getType(); | ||||||||
3517 | |||||||||
3518 | // If YShift is a 'lshr', swap the shifts around. | ||||||||
3519 | if (match(YShift, m_LShr(m_Value(), m_Value()))) | ||||||||
3520 | std::swap(XShift, YShift); | ||||||||
3521 | |||||||||
3522 | // The shifts must be in opposite directions. | ||||||||
3523 | auto XShiftOpcode = XShift->getOpcode(); | ||||||||
3524 | if (XShiftOpcode == YShift->getOpcode()) | ||||||||
3525 | return nullptr; // Do not care about same-direction shifts here. | ||||||||
3526 | |||||||||
3527 | Value *X, *XShAmt, *Y, *YShAmt; | ||||||||
3528 | match(XShift, m_BinOp(m_Value(X), m_ZExtOrSelf(m_Value(XShAmt)))); | ||||||||
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)) { | ||||||||
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()) | ||||||||
| |||||||||
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. | ||||||||
3654 | Value *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 | |||||||||
3716 | static 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. | ||||||||
3736 | Instruction *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); | ||||||||
| |||||||||
3743 | BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1); | ||||||||
3744 | if (!BO0
| ||||||||
3745 | return nullptr; | ||||||||
3746 | |||||||||
3747 | if (Instruction *NewICmp
| ||||||||
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)))) && | ||||||||
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)))) && | ||||||||
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
| ||||||||
3765 | NoOp0WrapProblem = | ||||||||
3766 | ICmpInst::isEquality(Pred) || | ||||||||
3767 | (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) || | ||||||||
3768 | (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap()); | ||||||||
3769 | if (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
| ||||||||
3779 | A = BO0->getOperand(0); | ||||||||
3780 | B = BO0->getOperand(1); | ||||||||
3781 | } | ||||||||
3782 | if (BO1
| ||||||||
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
| ||||||||
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
| ||||||||
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
| ||||||||
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-12~++20210115100614+a14c36fe27f5/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
| ||||||||
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
| ||||||||
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
| ||||||||
3837 | return new ICmpInst(CmpInst::ICMP_SLT, A, Op1); | ||||||||
3838 | |||||||||
3839 | // icmp sgt (A + 1), Op1 -> icmp sge A, Op1 | ||||||||
3840 | if (A
| ||||||||
3841 | return new ICmpInst(CmpInst::ICMP_SGE, A, Op1); | ||||||||
3842 | |||||||||
3843 | // icmp sgt Op0, (C + -1) -> icmp sge Op0, C | ||||||||
3844 | if (C
| ||||||||
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
| ||||||||
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
| ||||||||
3855 | return new ICmpInst(CmpInst::ICMP_SGT, Op0, C); | ||||||||
3856 | |||||||||
3857 | // icmp slt Op0, (C + 1) -> icmp sle Op0, C | ||||||||
3858 | if (C
| ||||||||
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
| ||||||||
3872 | return new ICmpInst(CmpInst::ICMP_ULT, A, Op1); | ||||||||
3873 | |||||||||
3874 | // icmp ugt (A + 1), Op0 -> icmp uge A, Op1 | ||||||||
3875 | if (A
| ||||||||
3876 | return new ICmpInst(CmpInst::ICMP_UGE, A, Op1); | ||||||||
3877 | |||||||||
3878 | // icmp uge Op0, (C + 1) -> icmp ugt Op0, C | ||||||||
3879 | if (C
| ||||||||
3880 | return new ICmpInst(CmpInst::ICMP_UGT, Op0, C); | ||||||||
3881 | |||||||||
3882 | // icmp ult Op0, (C + 1) -> icmp ule Op0, C | ||||||||
3883 | if (C
| ||||||||
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
| ||||||||
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
| ||||||||
3921 | A = BO0->getOperand(0); | ||||||||
3922 | B = BO0->getOperand(1); | ||||||||
3923 | } | ||||||||
3924 | if (BO1
| ||||||||
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
| ||||||||
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
| ||||||||
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
| ||||||||
3939 | return new ICmpInst(Pred, B, A); | ||||||||
3940 | // C u</u>= (C - D) --> C u</u>= D | ||||||||
3941 | if (C
| ||||||||
3942 | return new ICmpInst(Pred, C, D); | ||||||||
3943 | // (A - B) u>=/u< A --> B u>/u<= A iff B != 0 | ||||||||
3944 | if (A
| ||||||||
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
| ||||||||
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
| ||||||||
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
| ||||||||
3958 | return new ICmpInst(Pred, D, B); | ||||||||
3959 | |||||||||
3960 | // icmp (0-X) < cst --> x > -cst | ||||||||
3961 | if (NoOp0WrapProblem
| ||||||||
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 && | ||||||||
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
| ||||||||
3986 | SRem = BO0; | ||||||||
3987 | // icmp Y, (srem X, Y) | ||||||||
3988 | else if (BO1
| ||||||||
3989 | Op0 == BO1->getOperand(1)) | ||||||||
3990 | SRem = BO1; | ||||||||
3991 | if (SRem
| ||||||||
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
| ||||||||
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
| ||||||||
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
| ||||||||
4100 | return replaceInstUsesWith(I, V); | ||||||||
4101 | |||||||||
4102 | if (Value *V
| ||||||||
4103 | return replaceInstUsesWith(I, V); | ||||||||
4104 | |||||||||
4105 | if (Value *V
| ||||||||
4106 | return replaceInstUsesWith(I, V); | ||||||||
4107 | |||||||||
4108 | if (Value *V = foldShiftIntoShiftInAnotherHandOfAndInICmp(I, SQ, Builder)) | ||||||||
4109 | return replaceInstUsesWith(I, V); | ||||||||
4110 | |||||||||
4111 | return nullptr; | ||||||||
4112 | } | ||||||||
4113 | |||||||||
4114 | /// Fold icmp Pred min|max(X, Y), X. | ||||||||
4115 | static 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 | |||||||||
4201 | Instruction *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 | |||||||||
4376 | static 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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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). | ||||||||
4469 | Instruction *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 | |||||||||
4512 | static 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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
4524 | OverflowResult | ||||||||
4525 | InstCombinerImpl::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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
4549 | bool 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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
4612 | static 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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
4829 | static 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. | ||||||||
4866 | static 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 | /// | ||||||||
4894 | bool 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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
4916 | static 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. | ||||||||
4969 | bool 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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
4997 | Instruction *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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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 | |||||||||
5225 | llvm::Optional<std::pair<CmpInst::Predicate, Constant *>> | ||||||||
5226 | InstCombiner::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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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-12~++20210115100614+a14c36fe27f5/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. | ||||||||
5294 | static 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. | ||||||||
5316 | CmpInst *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 now let's adjust every user. | ||||||||
5332 | for (User *U : I.users()) { | ||||||||
5333 | switch (cast<Instruction>(U)->getOpcode()) { | ||||||||
5334 | case Instruction::Select: { | ||||||||
5335 | auto *SI = cast<SelectInst>(U); | ||||||||
5336 | SI->swapValues(); | ||||||||
5337 | SI->swapProfMetadata(); | ||||||||
5338 | break; | ||||||||
5339 | } | ||||||||
5340 | case Instruction::Br: | ||||||||
5341 | cast<BranchInst>(U)->swapSuccessors(); // swaps prof metadata too | ||||||||
5342 | break; | ||||||||
5343 | case Instruction::Xor: | ||||||||
5344 | replaceInstUsesWith(cast<Instruction>(*U), &I); | ||||||||
5345 | break; | ||||||||
5346 | default: | ||||||||
5347 | llvm_unreachable("Got unexpected user - out of sync with "::llvm::llvm_unreachable_internal("Got unexpected user - out of sync with " "canFreelyInvertAllUsersOf() ?", "/build/llvm-toolchain-snapshot-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5348) | ||||||||
5348 | "canFreelyInvertAllUsersOf() ?")::llvm::llvm_unreachable_internal("Got unexpected user - out of sync with " "canFreelyInvertAllUsersOf() ?", "/build/llvm-toolchain-snapshot-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5348); | ||||||||
5349 | } | ||||||||
5350 | } | ||||||||
5351 | |||||||||
5352 | return &I; | ||||||||
5353 | } | ||||||||
5354 | |||||||||
5355 | /// Integer compare with boolean values can always be turned into bitwise ops. | ||||||||
5356 | static Instruction *canonicalizeICmpBool(ICmpInst &I, | ||||||||
5357 | InstCombiner::BuilderTy &Builder) { | ||||||||
5358 | Value *A = I.getOperand(0), *B = I.getOperand(1); | ||||||||
5359 | 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-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5359, __PRETTY_FUNCTION__)); | ||||||||
5360 | |||||||||
5361 | // A boolean compared to true/false can be simplified to Op0/true/false in | ||||||||
5362 | // 14 out of the 20 (10 predicates * 2 constants) possible combinations. | ||||||||
5363 | // Cases not handled by InstSimplify are always 'not' of Op0. | ||||||||
5364 | if (match(B, m_Zero())) { | ||||||||
5365 | switch (I.getPredicate()) { | ||||||||
5366 | case CmpInst::ICMP_EQ: // A == 0 -> !A | ||||||||
5367 | case CmpInst::ICMP_ULE: // A <=u 0 -> !A | ||||||||
5368 | case CmpInst::ICMP_SGE: // A >=s 0 -> !A | ||||||||
5369 | return BinaryOperator::CreateNot(A); | ||||||||
5370 | default: | ||||||||
5371 | 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-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5371); | ||||||||
5372 | } | ||||||||
5373 | } else if (match(B, m_One())) { | ||||||||
5374 | switch (I.getPredicate()) { | ||||||||
5375 | case CmpInst::ICMP_NE: // A != 1 -> !A | ||||||||
5376 | case CmpInst::ICMP_ULT: // A <u 1 -> !A | ||||||||
5377 | case CmpInst::ICMP_SGT: // A >s -1 -> !A | ||||||||
5378 | return BinaryOperator::CreateNot(A); | ||||||||
5379 | default: | ||||||||
5380 | 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-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5380); | ||||||||
5381 | } | ||||||||
5382 | } | ||||||||
5383 | |||||||||
5384 | switch (I.getPredicate()) { | ||||||||
5385 | default: | ||||||||
5386 | llvm_unreachable("Invalid icmp instruction!")::llvm::llvm_unreachable_internal("Invalid icmp instruction!" , "/build/llvm-toolchain-snapshot-12~++20210115100614+a14c36fe27f5/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp" , 5386); | ||||||||
5387 | case ICmpInst::ICMP_EQ: | ||||||||
5388 | // icmp eq i1 A, B -> ~(A ^ B) | ||||||||
5389 | return BinaryOperator::CreateNot(Builder.CreateXor(A, B)); | ||||||||
5390 | |||||||||
5391 | case ICmpInst::ICMP_NE: | ||||||||
5392 | // icmp ne i1 A, B -> A ^ B | ||||||||
5393 | return BinaryOperator::CreateXor(A, B); | ||||||||
5394 | |||||||||
5395 | case ICmpInst::ICMP_UGT: | ||||||||
5396 | // icmp ugt -> icmp ult | ||||||||
5397 | std::swap(A, B); | ||||||||
5398 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
5399 | case ICmpInst::ICMP_ULT: | ||||||||
5400 | // icmp ult i1 A, B -> ~A & B | ||||||||
5401 | return BinaryOperator::CreateAnd(Builder.CreateNot(A), B); | ||||||||
5402 | |||||||||
5403 | case ICmpInst::ICMP_SGT: | ||||||||
5404 | // icmp sgt -> icmp slt | ||||||||
5405 | std::swap(A, B); | ||||||||
5406 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
5407 | case ICmpInst::ICMP_SLT: | ||||||||
5408 | // icmp slt i1 A, B -> A & ~B | ||||||||
5409 | return BinaryOperator::CreateAnd(Builder.CreateNot(B), A); | ||||||||
5410 | |||||||||
5411 | case ICmpInst::ICMP_UGE: | ||||||||
5412 | // icmp uge -> icmp ule | ||||||||
5413 | std::swap(A, B); | ||||||||
5414 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
5415 | case ICmpInst::ICMP_ULE: | ||||||||
5416 | // icmp ule i1 A, B -> ~A | B | ||||||||
5417 | return BinaryOperator::CreateOr(Builder.CreateNot(A), B); | ||||||||
5418 | |||||||||
5419 | case ICmpInst::ICMP_SGE: | ||||||||
5420 | // icmp sge -> icmp sle | ||||||||
5421 | std::swap(A, B); | ||||||||
5422 | LLVM_FALLTHROUGH[[gnu::fallthrough]]; | ||||||||
5423 | case ICmpInst::ICMP_SLE: | ||||||||
5424 | // icmp sle i1 A, B -> A | ~B | ||||||||
5425 | return BinaryOperator::CreateOr(Builder.CreateNot(B), A); | ||||||||
5426 | } | ||||||||
5427 | } | ||||||||
5428 | |||||||||
5429 | // Transform pattern like: | ||||||||
5430 | // (1 << Y) u<= X or ~(-1 << Y) u< X or ((1 << Y)+(-1)) u< X | ||||||||
5431 | // (1 << Y) u> X or ~(-1 << Y) u>= X or ((1 << Y)+(-1)) u>= X | ||||||||
5432 | // Into: | ||||||||
5433 | // (X l>> Y) != 0 | ||||||||
5434 | // (X l>> Y) == 0 | ||||||||
5435 | static Instruction *foldICmpWithHighBitMask(ICmpInst &Cmp, | ||||||||
5436 | InstCombiner::BuilderTy &Builder) { | ||||||||
5437 | ICmpInst::Predicate Pred, NewPred; | ||||||||
5438 | Value *X, *Y; | ||||||||
5439 | if (match(&Cmp, | ||||||||
5440 | m_c_ICmp(Pred, m_OneUse(m_Shl(m_One(), m_Value(Y))), m_Value(X)))) { | ||||||||
5441 | switch (Pred) { | ||||||||
5442 | case ICmpInst::ICMP_ULE: | ||||||||
5443 | NewPred = ICmpInst::ICMP_NE; | ||||||||
5444 | break; | ||||||||
5445 | case ICmpInst::ICMP_UGT: | ||||||||
5446 | NewPred = ICmpInst::ICMP_EQ; | ||||||||
5447 | break; | ||||||||
5448 | default: | ||||||||
5449 | return nullptr; | ||||||||
5450 | } | ||||||||
5451 | } else if (match(&Cmp, m_c_ICmp(Pred, | ||||||||
5452 | m_OneUse(m_CombineOr( | ||||||||
5453 | m_Not(m_Shl(m_AllOnes(), m_Value(Y))), | ||||||||
5454 | m_Add(m_Shl(m_One(), m_Value(Y)), | ||||||||
5455 | m_AllOnes()))), | ||||||||
5456 | m_Value(X)))) { | ||||||||
5457 | // The variant with 'add' is not canonical, (the variant with 'not' is) | ||||||||
5458 | // we only get it because it has extra uses, and can't be canonicalized, | ||||||||
5459 | |||||||||
5460 | switch (Pred) { | ||||||||
5461 | case ICmpInst::ICMP_ULT: | ||||||||
5462 | NewPred = ICmpInst::ICMP_NE; | ||||||||
5463 | break; | ||||||||
5464 | case ICmpInst::ICMP_UGE: | ||||||||
5465 | NewPred = ICmpInst::ICMP_EQ; | ||||||||
5466 | break; | ||||||||
5467 | default: | ||||||||
5468 | return nullptr; | ||||||||
5469 | } | ||||||||
5470 | } else | ||||||||
5471 | return nullptr; | ||||||||
5472 | |||||||||
5473 | Value *NewX = Builder.CreateLShr(X, Y, X->getName() + ".highbits"); | ||||||||
5474 | Constant *Zero = Constant::getNullValue(NewX->getType()); | ||||||||
5475 | return CmpInst::Create(Instruction::ICmp, NewPred, NewX, Zero); | ||||||||
5476 | } | ||||||||
5477 | |||||||||
5478 | static Instruction *foldVectorCmp(CmpInst &Cmp, | ||||||||
5479 | InstCombiner::BuilderTy &Builder) { | ||||||||
5480 | const CmpInst::Predicate Pred = Cmp.getPredicate(); | ||||||||
5481 | Value *LHS = Cmp.getOperand(0), *RHS = Cmp.getOperand(1); | ||||||||
5482 | Value *V1, *V2; | ||||||||
5483 | ArrayRef<int> M; | ||||||||
5484 | if (!match(LHS, m_Shuffle(m_Value(V1), m_Undef(), m_Mask(M)))) | ||||||||
5485 | return nullptr; | ||||||||
5486 | |||||||||
5487 | // If both arguments of the cmp are shuffles that use the same mask and | ||||||||
5488 | // shuffle within a single vector, move the shuffle after the cmp: | ||||||||
5489 | // cmp (shuffle V1, M), (shuffle V2, M) --> shuffle (cmp V1, V2), M | ||||||||
5490 | Type *V1Ty = V1->getType(); | ||||||||
5491 | if (match(RHS, m_Shuffle(m_Value(V2), m_Undef(), m_SpecificMask(M))) && | ||||||||
5492 | V1Ty == V2->getType() && (LHS->hasOneUse() || RHS->hasOneUse())) { | ||||||||
5493 | Value *NewCmp = Builder.CreateCmp(Pred, V1, V2); | ||||||||
5494 | return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), M); | ||||||||
5495 | } | ||||||||
5496 | |||||||||
5497 | // Try to canonicalize compare with splatted operand and splat constant. | ||||||||
5498 | // TODO: We could generalize this for more than splats. See/use the code in | ||||||||
5499 | // InstCombiner::foldVectorBinop(). | ||||||||
5500 | Constant *C; | ||||||||
5501 | if (!LHS->hasOneUse() || !match(RHS, m_Constant(C))) | ||||||||
5502 | return nullptr; | ||||||||
5503 | |||||||||
5504 | // Length-changing splats are ok, so adjust the constants as needed: | ||||||||
5505 | // cmp (shuffle V1, M), C --> shuffle (cmp V1, C'), M | ||||||||
5506 | Constant *ScalarC = C->getSplatValue(/* AllowUndefs */ true); | ||||||||
5507 | int MaskSplatIndex; | ||||||||
5508 | if (ScalarC && match(M, m_SplatOrUndefMask(MaskSplatIndex))) { | ||||||||
5509 | // We allow undefs in matching, but this transform removes those for safety. | ||||||||
5510 | // Demanded elements analysis should be able to recover some/all of that. | ||||||||
5511 | C = ConstantVector::getSplat(cast<VectorType>(V1Ty)->getElementCount(), | ||||||||
5512 | ScalarC); | ||||||||
5513 | SmallVector<int, 8> NewM(M.size(), MaskSplatIndex); | ||||||||
5514 | Value *NewCmp = Builder.CreateCmp(Pred, V1, C); | ||||||||
5515 | return new ShuffleVectorInst(NewCmp, UndefValue::get(NewCmp->getType()), | ||||||||
5516 | NewM); | ||||||||
5517 | } | ||||||||
5518 | |||||||||
5519 | return nullptr; | ||||||||
5520 | } | ||||||||
5521 | |||||||||
5522 | // extract(uadd.with.overflow(A, B), 0) ult A | ||||||||
5523 | // -> extract(uadd.with.overflow(A, B), 1) | ||||||||
5524 | static Instruction *foldICmpOfUAddOv(ICmpInst &I) { | ||||||||
5525 | CmpInst::Predicate Pred = I.getPredicate(); | ||||||||
5526 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
5527 | |||||||||
5528 | Value *UAddOv; | ||||||||
5529 | Value *A, *B; | ||||||||
5530 | auto UAddOvResultPat = m_ExtractValue<0>( | ||||||||
5531 | m_Intrinsic<Intrinsic::uadd_with_overflow>(m_Value(A), m_Value(B))); | ||||||||
5532 | if (match(Op0, UAddOvResultPat) && | ||||||||
5533 | ((Pred == ICmpInst::ICMP_ULT && (Op1 == A || Op1 == B)) || | ||||||||
5534 | (Pred == ICmpInst::ICMP_EQ && match(Op1, m_ZeroInt()) && | ||||||||
5535 | (match(A, m_One()) || match(B, m_One()))) || | ||||||||
5536 | (Pred == ICmpInst::ICMP_NE && match(Op1, m_AllOnes()) && | ||||||||
5537 | (match(A, m_AllOnes()) || match(B, m_AllOnes()))))) | ||||||||
5538 | // extract(uadd.with.overflow(A, B), 0) < A | ||||||||
5539 | // extract(uadd.with.overflow(A, 1), 0) == 0 | ||||||||
5540 | // extract(uadd.with.overflow(A, -1), 0) != -1 | ||||||||
5541 | UAddOv = cast<ExtractValueInst>(Op0)->getAggregateOperand(); | ||||||||
5542 | else if (match(Op1, UAddOvResultPat) && | ||||||||
5543 | Pred == ICmpInst::ICMP_UGT && (Op0 == A || Op0 == B)) | ||||||||
5544 | // A > extract(uadd.with.overflow(A, B), 0) | ||||||||
5545 | UAddOv = cast<ExtractValueInst>(Op1)->getAggregateOperand(); | ||||||||
5546 | else | ||||||||
5547 | return nullptr; | ||||||||
5548 | |||||||||
5549 | return ExtractValueInst::Create(UAddOv, 1); | ||||||||
5550 | } | ||||||||
5551 | |||||||||
5552 | Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) { | ||||||||
5553 | bool Changed = false; | ||||||||
5554 | const SimplifyQuery Q = SQ.getWithInstruction(&I); | ||||||||
5555 | Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); | ||||||||
5556 | unsigned Op0Cplxity = getComplexity(Op0); | ||||||||
5557 | unsigned Op1Cplxity = getComplexity(Op1); | ||||||||
5558 | |||||||||
5559 | /// Orders the operands of the compare so that they are listed from most | ||||||||
5560 | /// complex to least complex. This puts constants before unary operators, | ||||||||
5561 | /// before binary operators. | ||||||||
5562 | if (Op0Cplxity < Op1Cplxity || | ||||||||
5563 | (Op0Cplxity == Op1Cplxity && swapMayExposeCSEOpportunities(Op0, Op1))) { | ||||||||
5564 | I.swapOperands(); | ||||||||
5565 | std::swap(Op0, Op1); | ||||||||
5566 | Changed = true; | ||||||||
5567 | } | ||||||||
5568 | |||||||||
5569 | if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, Q)) | ||||||||
5570 | return replaceInstUsesWith(I, V); | ||||||||
5571 | |||||||||
5572 | // Comparing -val or val with non-zero is the same as just comparing val | ||||||||
5573 | // ie, abs(val) != 0 -> val != 0 | ||||||||
5574 | if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero())) { | ||||||||
5575 | Value *Cond, *SelectTrue, *SelectFalse; | ||||||||
5576 | if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue), | ||||||||
5577 | m_Value(SelectFalse)))) { | ||||||||
5578 | if (Value *V = dyn_castNegVal(SelectTrue)) { | ||||||||
5579 | if (V == SelectFalse) | ||||||||
5580 | return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); | ||||||||
5581 | } | ||||||||
5582 | else if (Value *V = dyn_castNegVal(SelectFalse)) { | ||||||||
5583 | if (V == SelectTrue) | ||||||||
5584 | return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1); | ||||||||
5585 | } | ||||||||
5586 | } | ||||||||
5587 | } | ||||||||
5588 | |||||||||
5589 | if (Op0->getType()->isIntOrIntVectorTy(1)) | ||||||||
5590 | if (Instruction *Res = canonicalizeICmpBool(I, Builder)) | ||||||||
5591 | return Res; | ||||||||
5592 | |||||||||
5593 | if (Instruction *Res = canonicalizeCmpWithConstant(I)) | ||||||||
5594 | return Res; | ||||||||
5595 | |||||||||
5596 | if (Instruction *Res = canonicalizeICmpPredicate(I)) | ||||||||
5597 | return Res; | ||||||||
5598 | |||||||||
5599 | if (Instruction *Res = foldICmpWithConstant(I)) | ||||||||
5600 | return Res; | ||||||||
5601 | |||||||||
5602 | if (Instruction *Res = foldICmpWithDominatingICmp(I)) | ||||||||
5603 | return Res; | ||||||||
5604 | |||||||||
5605 | if (Instruction *Res = foldICmpBinOp(I, Q)) | ||||||||
5606 | return Res; | ||||||||
5607 | |||||||||
5608 | if (Instruction *Res = foldICmpUsingKnownBits(I)) | ||||||||
5609 | return Res; | ||||||||
5610 | |||||||||
5611 | // Test if the ICmpInst instruction is used exclusively by a select as | ||||||||
5612 | // part of a minimum or maximum operation. If so, refrain from doing | ||||||||
5613 | // any other folding. This helps out other analyses which understand | ||||||||
5614 | // non-obfuscated minimum and maximum idioms, such as ScalarEvolution | ||||||||
5615 | // and CodeGen. And in this case, at least one of the comparison | ||||||||
5616 | // operands has at least one user besides the compare (the select), | ||||||||
5617 | // which would often largely negate the benefit of folding anyway. | ||||||||
5618 | // | ||||||||
5619 | // Do the same for the other patterns recognized by matchSelectPattern. | ||||||||
5620 | if |