Bug Summary

File:llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
Warning:line 361, column 7
Value stored to 'Ok' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name InstCombineAndOrXor.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/InstCombine -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/InstCombine -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/Transforms/InstCombine -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
1//===- InstCombineAndOrXor.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 visitAnd, visitOr, and visitXor functions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "InstCombineInternal.h"
14#include "llvm/Analysis/CmpInstAnalysis.h"
15#include "llvm/Analysis/InstructionSimplify.h"
16#include "llvm/IR/ConstantRange.h"
17#include "llvm/IR/Intrinsics.h"
18#include "llvm/IR/PatternMatch.h"
19#include "llvm/Transforms/InstCombine/InstCombiner.h"
20#include "llvm/Transforms/Utils/Local.h"
21
22using namespace llvm;
23using namespace PatternMatch;
24
25#define DEBUG_TYPE"instcombine" "instcombine"
26
27/// Similar to getICmpCode but for FCmpInst. This encodes a fcmp predicate into
28/// a four bit mask.
29static unsigned getFCmpCode(FCmpInst::Predicate CC) {
30 assert(FCmpInst::FCMP_FALSE <= CC && CC <= FCmpInst::FCMP_TRUE &&(static_cast<void> (0))
31 "Unexpected FCmp predicate!")(static_cast<void> (0));
32 // Take advantage of the bit pattern of FCmpInst::Predicate here.
33 // U L G E
34 static_assert(FCmpInst::FCMP_FALSE == 0, ""); // 0 0 0 0
35 static_assert(FCmpInst::FCMP_OEQ == 1, ""); // 0 0 0 1
36 static_assert(FCmpInst::FCMP_OGT == 2, ""); // 0 0 1 0
37 static_assert(FCmpInst::FCMP_OGE == 3, ""); // 0 0 1 1
38 static_assert(FCmpInst::FCMP_OLT == 4, ""); // 0 1 0 0
39 static_assert(FCmpInst::FCMP_OLE == 5, ""); // 0 1 0 1
40 static_assert(FCmpInst::FCMP_ONE == 6, ""); // 0 1 1 0
41 static_assert(FCmpInst::FCMP_ORD == 7, ""); // 0 1 1 1
42 static_assert(FCmpInst::FCMP_UNO == 8, ""); // 1 0 0 0
43 static_assert(FCmpInst::FCMP_UEQ == 9, ""); // 1 0 0 1
44 static_assert(FCmpInst::FCMP_UGT == 10, ""); // 1 0 1 0
45 static_assert(FCmpInst::FCMP_UGE == 11, ""); // 1 0 1 1
46 static_assert(FCmpInst::FCMP_ULT == 12, ""); // 1 1 0 0
47 static_assert(FCmpInst::FCMP_ULE == 13, ""); // 1 1 0 1
48 static_assert(FCmpInst::FCMP_UNE == 14, ""); // 1 1 1 0
49 static_assert(FCmpInst::FCMP_TRUE == 15, ""); // 1 1 1 1
50 return CC;
51}
52
53/// This is the complement of getICmpCode, which turns an opcode and two
54/// operands into either a constant true or false, or a brand new ICmp
55/// instruction. The sign is passed in to determine which kind of predicate to
56/// use in the new icmp instruction.
57static Value *getNewICmpValue(unsigned Code, bool Sign, Value *LHS, Value *RHS,
58 InstCombiner::BuilderTy &Builder) {
59 ICmpInst::Predicate NewPred;
60 if (Constant *TorF = getPredForICmpCode(Code, Sign, LHS->getType(), NewPred))
61 return TorF;
62 return Builder.CreateICmp(NewPred, LHS, RHS);
63}
64
65/// This is the complement of getFCmpCode, which turns an opcode and two
66/// operands into either a FCmp instruction, or a true/false constant.
67static Value *getFCmpValue(unsigned Code, Value *LHS, Value *RHS,
68 InstCombiner::BuilderTy &Builder) {
69 const auto Pred = static_cast<FCmpInst::Predicate>(Code);
70 assert(FCmpInst::FCMP_FALSE <= Pred && Pred <= FCmpInst::FCMP_TRUE &&(static_cast<void> (0))
71 "Unexpected FCmp predicate!")(static_cast<void> (0));
72 if (Pred == FCmpInst::FCMP_FALSE)
73 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
74 if (Pred == FCmpInst::FCMP_TRUE)
75 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
76 return Builder.CreateFCmp(Pred, LHS, RHS);
77}
78
79/// Transform BITWISE_OP(BSWAP(A),BSWAP(B)) or
80/// BITWISE_OP(BSWAP(A), Constant) to BSWAP(BITWISE_OP(A, B))
81/// \param I Binary operator to transform.
82/// \return Pointer to node that must replace the original binary operator, or
83/// null pointer if no transformation was made.
84static Value *SimplifyBSwap(BinaryOperator &I,
85 InstCombiner::BuilderTy &Builder) {
86 assert(I.isBitwiseLogicOp() && "Unexpected opcode for bswap simplifying")(static_cast<void> (0));
87
88 Value *OldLHS = I.getOperand(0);
89 Value *OldRHS = I.getOperand(1);
90
91 Value *NewLHS;
92 if (!match(OldLHS, m_BSwap(m_Value(NewLHS))))
93 return nullptr;
94
95 Value *NewRHS;
96 const APInt *C;
97
98 if (match(OldRHS, m_BSwap(m_Value(NewRHS)))) {
99 // OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
100 if (!OldLHS->hasOneUse() && !OldRHS->hasOneUse())
101 return nullptr;
102 // NewRHS initialized by the matcher.
103 } else if (match(OldRHS, m_APInt(C))) {
104 // OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )
105 if (!OldLHS->hasOneUse())
106 return nullptr;
107 NewRHS = ConstantInt::get(I.getType(), C->byteSwap());
108 } else
109 return nullptr;
110
111 Value *BinOp = Builder.CreateBinOp(I.getOpcode(), NewLHS, NewRHS);
112 Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::bswap,
113 I.getType());
114 return Builder.CreateCall(F, BinOp);
115}
116
117/// Emit a computation of: (V >= Lo && V < Hi) if Inside is true, otherwise
118/// (V < Lo || V >= Hi). This method expects that Lo < Hi. IsSigned indicates
119/// whether to treat V, Lo, and Hi as signed or not.
120Value *InstCombinerImpl::insertRangeTest(Value *V, const APInt &Lo,
121 const APInt &Hi, bool isSigned,
122 bool Inside) {
123 assert((isSigned ? Lo.slt(Hi) : Lo.ult(Hi)) &&(static_cast<void> (0))
124 "Lo is not < Hi in range emission code!")(static_cast<void> (0));
125
126 Type *Ty = V->getType();
127
128 // V >= Min && V < Hi --> V < Hi
129 // V < Min || V >= Hi --> V >= Hi
130 ICmpInst::Predicate Pred = Inside ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_UGE;
131 if (isSigned ? Lo.isMinSignedValue() : Lo.isMinValue()) {
132 Pred = isSigned ? ICmpInst::getSignedPredicate(Pred) : Pred;
133 return Builder.CreateICmp(Pred, V, ConstantInt::get(Ty, Hi));
134 }
135
136 // V >= Lo && V < Hi --> V - Lo u< Hi - Lo
137 // V < Lo || V >= Hi --> V - Lo u>= Hi - Lo
138 Value *VMinusLo =
139 Builder.CreateSub(V, ConstantInt::get(Ty, Lo), V->getName() + ".off");
140 Constant *HiMinusLo = ConstantInt::get(Ty, Hi - Lo);
141 return Builder.CreateICmp(Pred, VMinusLo, HiMinusLo);
142}
143
144/// Classify (icmp eq (A & B), C) and (icmp ne (A & B), C) as matching patterns
145/// that can be simplified.
146/// One of A and B is considered the mask. The other is the value. This is
147/// described as the "AMask" or "BMask" part of the enum. If the enum contains
148/// only "Mask", then both A and B can be considered masks. If A is the mask,
149/// then it was proven that (A & C) == C. This is trivial if C == A or C == 0.
150/// If both A and C are constants, this proof is also easy.
151/// For the following explanations, we assume that A is the mask.
152///
153/// "AllOnes" declares that the comparison is true only if (A & B) == A or all
154/// bits of A are set in B.
155/// Example: (icmp eq (A & 3), 3) -> AMask_AllOnes
156///
157/// "AllZeros" declares that the comparison is true only if (A & B) == 0 or all
158/// bits of A are cleared in B.
159/// Example: (icmp eq (A & 3), 0) -> Mask_AllZeroes
160///
161/// "Mixed" declares that (A & B) == C and C might or might not contain any
162/// number of one bits and zero bits.
163/// Example: (icmp eq (A & 3), 1) -> AMask_Mixed
164///
165/// "Not" means that in above descriptions "==" should be replaced by "!=".
166/// Example: (icmp ne (A & 3), 3) -> AMask_NotAllOnes
167///
168/// If the mask A contains a single bit, then the following is equivalent:
169/// (icmp eq (A & B), A) equals (icmp ne (A & B), 0)
170/// (icmp ne (A & B), A) equals (icmp eq (A & B), 0)
171enum MaskedICmpType {
172 AMask_AllOnes = 1,
173 AMask_NotAllOnes = 2,
174 BMask_AllOnes = 4,
175 BMask_NotAllOnes = 8,
176 Mask_AllZeros = 16,
177 Mask_NotAllZeros = 32,
178 AMask_Mixed = 64,
179 AMask_NotMixed = 128,
180 BMask_Mixed = 256,
181 BMask_NotMixed = 512
182};
183
184/// Return the set of patterns (from MaskedICmpType) that (icmp SCC (A & B), C)
185/// satisfies.
186static unsigned getMaskedICmpType(Value *A, Value *B, Value *C,
187 ICmpInst::Predicate Pred) {
188 ConstantInt *ACst = dyn_cast<ConstantInt>(A);
189 ConstantInt *BCst = dyn_cast<ConstantInt>(B);
190 ConstantInt *CCst = dyn_cast<ConstantInt>(C);
191 bool IsEq = (Pred == ICmpInst::ICMP_EQ);
192 bool IsAPow2 = (ACst && !ACst->isZero() && ACst->getValue().isPowerOf2());
193 bool IsBPow2 = (BCst && !BCst->isZero() && BCst->getValue().isPowerOf2());
194 unsigned MaskVal = 0;
195 if (CCst && CCst->isZero()) {
196 // if C is zero, then both A and B qualify as mask
197 MaskVal |= (IsEq ? (Mask_AllZeros | AMask_Mixed | BMask_Mixed)
198 : (Mask_NotAllZeros | AMask_NotMixed | BMask_NotMixed));
199 if (IsAPow2)
200 MaskVal |= (IsEq ? (AMask_NotAllOnes | AMask_NotMixed)
201 : (AMask_AllOnes | AMask_Mixed));
202 if (IsBPow2)
203 MaskVal |= (IsEq ? (BMask_NotAllOnes | BMask_NotMixed)
204 : (BMask_AllOnes | BMask_Mixed));
205 return MaskVal;
206 }
207
208 if (A == C) {
209 MaskVal |= (IsEq ? (AMask_AllOnes | AMask_Mixed)
210 : (AMask_NotAllOnes | AMask_NotMixed));
211 if (IsAPow2)
212 MaskVal |= (IsEq ? (Mask_NotAllZeros | AMask_NotMixed)
213 : (Mask_AllZeros | AMask_Mixed));
214 } else if (ACst && CCst && ConstantExpr::getAnd(ACst, CCst) == CCst) {
215 MaskVal |= (IsEq ? AMask_Mixed : AMask_NotMixed);
216 }
217
218 if (B == C) {
219 MaskVal |= (IsEq ? (BMask_AllOnes | BMask_Mixed)
220 : (BMask_NotAllOnes | BMask_NotMixed));
221 if (IsBPow2)
222 MaskVal |= (IsEq ? (Mask_NotAllZeros | BMask_NotMixed)
223 : (Mask_AllZeros | BMask_Mixed));
224 } else if (BCst && CCst && ConstantExpr::getAnd(BCst, CCst) == CCst) {
225 MaskVal |= (IsEq ? BMask_Mixed : BMask_NotMixed);
226 }
227
228 return MaskVal;
229}
230
231/// Convert an analysis of a masked ICmp into its equivalent if all boolean
232/// operations had the opposite sense. Since each "NotXXX" flag (recording !=)
233/// is adjacent to the corresponding normal flag (recording ==), this just
234/// involves swapping those bits over.
235static unsigned conjugateICmpMask(unsigned Mask) {
236 unsigned NewMask;
237 NewMask = (Mask & (AMask_AllOnes | BMask_AllOnes | Mask_AllZeros |
238 AMask_Mixed | BMask_Mixed))
239 << 1;
240
241 NewMask |= (Mask & (AMask_NotAllOnes | BMask_NotAllOnes | Mask_NotAllZeros |
242 AMask_NotMixed | BMask_NotMixed))
243 >> 1;
244
245 return NewMask;
246}
247
248// Adapts the external decomposeBitTestICmp for local use.
249static bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
250 Value *&X, Value *&Y, Value *&Z) {
251 APInt Mask;
252 if (!llvm::decomposeBitTestICmp(LHS, RHS, Pred, X, Mask))
253 return false;
254
255 Y = ConstantInt::get(X->getType(), Mask);
256 Z = ConstantInt::get(X->getType(), 0);
257 return true;
258}
259
260/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E).
261/// Return the pattern classes (from MaskedICmpType) for the left hand side and
262/// the right hand side as a pair.
263/// LHS and RHS are the left hand side and the right hand side ICmps and PredL
264/// and PredR are their predicates, respectively.
265static
266Optional<std::pair<unsigned, unsigned>>
267getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C,
268 Value *&D, Value *&E, ICmpInst *LHS,
269 ICmpInst *RHS,
270 ICmpInst::Predicate &PredL,
271 ICmpInst::Predicate &PredR) {
272 // vectors are not (yet?) supported. Don't support pointers either.
273 if (!LHS->getOperand(0)->getType()->isIntegerTy() ||
274 !RHS->getOperand(0)->getType()->isIntegerTy())
275 return None;
276
277 // Here comes the tricky part:
278 // LHS might be of the form L11 & L12 == X, X == L21 & L22,
279 // and L11 & L12 == L21 & L22. The same goes for RHS.
280 // Now we must find those components L** and R**, that are equal, so
281 // that we can extract the parameters A, B, C, D, and E for the canonical
282 // above.
283 Value *L1 = LHS->getOperand(0);
284 Value *L2 = LHS->getOperand(1);
285 Value *L11, *L12, *L21, *L22;
286 // Check whether the icmp can be decomposed into a bit test.
287 if (decomposeBitTestICmp(L1, L2, PredL, L11, L12, L2)) {
288 L21 = L22 = L1 = nullptr;
289 } else {
290 // Look for ANDs in the LHS icmp.
291 if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) {
292 // Any icmp can be viewed as being trivially masked; if it allows us to
293 // remove one, it's worth it.
294 L11 = L1;
295 L12 = Constant::getAllOnesValue(L1->getType());
296 }
297
298 if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) {
299 L21 = L2;
300 L22 = Constant::getAllOnesValue(L2->getType());
301 }
302 }
303
304 // Bail if LHS was a icmp that can't be decomposed into an equality.
305 if (!ICmpInst::isEquality(PredL))
306 return None;
307
308 Value *R1 = RHS->getOperand(0);
309 Value *R2 = RHS->getOperand(1);
310 Value *R11, *R12;
311 bool Ok = false;
312 if (decomposeBitTestICmp(R1, R2, PredR, R11, R12, R2)) {
313 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
314 A = R11;
315 D = R12;
316 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
317 A = R12;
318 D = R11;
319 } else {
320 return None;
321 }
322 E = R2;
323 R1 = nullptr;
324 Ok = true;
325 } else {
326 if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) {
327 // As before, model no mask as a trivial mask if it'll let us do an
328 // optimization.
329 R11 = R1;
330 R12 = Constant::getAllOnesValue(R1->getType());
331 }
332
333 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
334 A = R11;
335 D = R12;
336 E = R2;
337 Ok = true;
338 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
339 A = R12;
340 D = R11;
341 E = R2;
342 Ok = true;
343 }
344 }
345
346 // Bail if RHS was a icmp that can't be decomposed into an equality.
347 if (!ICmpInst::isEquality(PredR))
348 return None;
349
350 // Look for ANDs on the right side of the RHS icmp.
351 if (!Ok) {
352 if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) {
353 R11 = R2;
354 R12 = Constant::getAllOnesValue(R2->getType());
355 }
356
357 if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
358 A = R11;
359 D = R12;
360 E = R1;
361 Ok = true;
Value stored to 'Ok' is never read
362 } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
363 A = R12;
364 D = R11;
365 E = R1;
366 Ok = true;
367 } else {
368 return None;
369 }
370
371 assert(Ok && "Failed to find AND on the right side of the RHS icmp.")(static_cast<void> (0));
372 }
373
374 if (L11 == A) {
375 B = L12;
376 C = L2;
377 } else if (L12 == A) {
378 B = L11;
379 C = L2;
380 } else if (L21 == A) {
381 B = L22;
382 C = L1;
383 } else if (L22 == A) {
384 B = L21;
385 C = L1;
386 }
387
388 unsigned LeftType = getMaskedICmpType(A, B, C, PredL);
389 unsigned RightType = getMaskedICmpType(A, D, E, PredR);
390 return Optional<std::pair<unsigned, unsigned>>(std::make_pair(LeftType, RightType));
391}
392
393/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E) into a single
394/// (icmp(A & X) ==/!= Y), where the left-hand side is of type Mask_NotAllZeros
395/// and the right hand side is of type BMask_Mixed. For example,
396/// (icmp (A & 12) != 0) & (icmp (A & 15) == 8) -> (icmp (A & 15) == 8).
397static Value *foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
398 ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, Value *A, Value *B, Value *C,
399 Value *D, Value *E, ICmpInst::Predicate PredL, ICmpInst::Predicate PredR,
400 InstCombiner::BuilderTy &Builder) {
401 // We are given the canonical form:
402 // (icmp ne (A & B), 0) & (icmp eq (A & D), E).
403 // where D & E == E.
404 //
405 // If IsAnd is false, we get it in negated form:
406 // (icmp eq (A & B), 0) | (icmp ne (A & D), E) ->
407 // !((icmp ne (A & B), 0) & (icmp eq (A & D), E)).
408 //
409 // We currently handle the case of B, C, D, E are constant.
410 //
411 ConstantInt *BCst, *CCst, *DCst, *ECst;
412 if (!match(B, m_ConstantInt(BCst)) || !match(C, m_ConstantInt(CCst)) ||
413 !match(D, m_ConstantInt(DCst)) || !match(E, m_ConstantInt(ECst)))
414 return nullptr;
415
416 ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
417
418 // Update E to the canonical form when D is a power of two and RHS is
419 // canonicalized as,
420 // (icmp ne (A & D), 0) -> (icmp eq (A & D), D) or
421 // (icmp ne (A & D), D) -> (icmp eq (A & D), 0).
422 if (PredR != NewCC)
423 ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst));
424
425 // If B or D is zero, skip because if LHS or RHS can be trivially folded by
426 // other folding rules and this pattern won't apply any more.
427 if (BCst->getValue() == 0 || DCst->getValue() == 0)
428 return nullptr;
429
430 // If B and D don't intersect, ie. (B & D) == 0, no folding because we can't
431 // deduce anything from it.
432 // For example,
433 // (icmp ne (A & 12), 0) & (icmp eq (A & 3), 1) -> no folding.
434 if ((BCst->getValue() & DCst->getValue()) == 0)
435 return nullptr;
436
437 // If the following two conditions are met:
438 //
439 // 1. mask B covers only a single bit that's not covered by mask D, that is,
440 // (B & (B ^ D)) is a power of 2 (in other words, B minus the intersection of
441 // B and D has only one bit set) and,
442 //
443 // 2. RHS (and E) indicates that the rest of B's bits are zero (in other
444 // words, the intersection of B and D is zero), that is, ((B & D) & E) == 0
445 //
446 // then that single bit in B must be one and thus the whole expression can be
447 // folded to
448 // (A & (B | D)) == (B & (B ^ D)) | E.
449 //
450 // For example,
451 // (icmp ne (A & 12), 0) & (icmp eq (A & 7), 1) -> (icmp eq (A & 15), 9)
452 // (icmp ne (A & 15), 0) & (icmp eq (A & 7), 0) -> (icmp eq (A & 15), 8)
453 if ((((BCst->getValue() & DCst->getValue()) & ECst->getValue()) == 0) &&
454 (BCst->getValue() & (BCst->getValue() ^ DCst->getValue())).isPowerOf2()) {
455 APInt BorD = BCst->getValue() | DCst->getValue();
456 APInt BandBxorDorE = (BCst->getValue() & (BCst->getValue() ^ DCst->getValue())) |
457 ECst->getValue();
458 Value *NewMask = ConstantInt::get(BCst->getType(), BorD);
459 Value *NewMaskedValue = ConstantInt::get(BCst->getType(), BandBxorDorE);
460 Value *NewAnd = Builder.CreateAnd(A, NewMask);
461 return Builder.CreateICmp(NewCC, NewAnd, NewMaskedValue);
462 }
463
464 auto IsSubSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) {
465 return (C1->getValue() & C2->getValue()) == C1->getValue();
466 };
467 auto IsSuperSetOrEqual = [](ConstantInt *C1, ConstantInt *C2) {
468 return (C1->getValue() & C2->getValue()) == C2->getValue();
469 };
470
471 // In the following, we consider only the cases where B is a superset of D, B
472 // is a subset of D, or B == D because otherwise there's at least one bit
473 // covered by B but not D, in which case we can't deduce much from it, so
474 // no folding (aside from the single must-be-one bit case right above.)
475 // For example,
476 // (icmp ne (A & 14), 0) & (icmp eq (A & 3), 1) -> no folding.
477 if (!IsSubSetOrEqual(BCst, DCst) && !IsSuperSetOrEqual(BCst, DCst))
478 return nullptr;
479
480 // At this point, either B is a superset of D, B is a subset of D or B == D.
481
482 // If E is zero, if B is a subset of (or equal to) D, LHS and RHS contradict
483 // and the whole expression becomes false (or true if negated), otherwise, no
484 // folding.
485 // For example,
486 // (icmp ne (A & 3), 0) & (icmp eq (A & 7), 0) -> false.
487 // (icmp ne (A & 15), 0) & (icmp eq (A & 3), 0) -> no folding.
488 if (ECst->isZero()) {
489 if (IsSubSetOrEqual(BCst, DCst))
490 return ConstantInt::get(LHS->getType(), !IsAnd);
491 return nullptr;
492 }
493
494 // At this point, B, D, E aren't zero and (B & D) == B, (B & D) == D or B ==
495 // D. If B is a superset of (or equal to) D, since E is not zero, LHS is
496 // subsumed by RHS (RHS implies LHS.) So the whole expression becomes
497 // RHS. For example,
498 // (icmp ne (A & 255), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
499 // (icmp ne (A & 15), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
500 if (IsSuperSetOrEqual(BCst, DCst))
501 return RHS;
502 // Otherwise, B is a subset of D. If B and E have a common bit set,
503 // ie. (B & E) != 0, then LHS is subsumed by RHS. For example.
504 // (icmp ne (A & 12), 0) & (icmp eq (A & 15), 8) -> (icmp eq (A & 15), 8).
505 assert(IsSubSetOrEqual(BCst, DCst) && "Precondition due to above code")(static_cast<void> (0));
506 if ((BCst->getValue() & ECst->getValue()) != 0)
507 return RHS;
508 // Otherwise, LHS and RHS contradict and the whole expression becomes false
509 // (or true if negated.) For example,
510 // (icmp ne (A & 7), 0) & (icmp eq (A & 15), 8) -> false.
511 // (icmp ne (A & 6), 0) & (icmp eq (A & 15), 8) -> false.
512 return ConstantInt::get(LHS->getType(), !IsAnd);
513}
514
515/// Try to fold (icmp(A & B) ==/!= 0) &/| (icmp(A & D) ==/!= E) into a single
516/// (icmp(A & X) ==/!= Y), where the left-hand side and the right hand side
517/// aren't of the common mask pattern type.
518static Value *foldLogOpOfMaskedICmpsAsymmetric(
519 ICmpInst *LHS, ICmpInst *RHS, bool IsAnd, Value *A, Value *B, Value *C,
520 Value *D, Value *E, ICmpInst::Predicate PredL, ICmpInst::Predicate PredR,
521 unsigned LHSMask, unsigned RHSMask, InstCombiner::BuilderTy &Builder) {
522 assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) &&(static_cast<void> (0))
523 "Expected equality predicates for masked type of icmps.")(static_cast<void> (0));
524 // Handle Mask_NotAllZeros-BMask_Mixed cases.
525 // (icmp ne/eq (A & B), C) &/| (icmp eq/ne (A & D), E), or
526 // (icmp eq/ne (A & B), C) &/| (icmp ne/eq (A & D), E)
527 // which gets swapped to
528 // (icmp ne/eq (A & D), E) &/| (icmp eq/ne (A & B), C).
529 if (!IsAnd) {
530 LHSMask = conjugateICmpMask(LHSMask);
531 RHSMask = conjugateICmpMask(RHSMask);
532 }
533 if ((LHSMask & Mask_NotAllZeros) && (RHSMask & BMask_Mixed)) {
534 if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
535 LHS, RHS, IsAnd, A, B, C, D, E,
536 PredL, PredR, Builder)) {
537 return V;
538 }
539 } else if ((LHSMask & BMask_Mixed) && (RHSMask & Mask_NotAllZeros)) {
540 if (Value *V = foldLogOpOfMaskedICmps_NotAllZeros_BMask_Mixed(
541 RHS, LHS, IsAnd, A, D, E, B, C,
542 PredR, PredL, Builder)) {
543 return V;
544 }
545 }
546 return nullptr;
547}
548
549/// Try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
550/// into a single (icmp(A & X) ==/!= Y).
551static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
552 InstCombiner::BuilderTy &Builder) {
553 Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr, *E = nullptr;
554 ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
555 Optional<std::pair<unsigned, unsigned>> MaskPair =
556 getMaskedTypeForICmpPair(A, B, C, D, E, LHS, RHS, PredL, PredR);
557 if (!MaskPair)
558 return nullptr;
559 assert(ICmpInst::isEquality(PredL) && ICmpInst::isEquality(PredR) &&(static_cast<void> (0))
560 "Expected equality predicates for masked type of icmps.")(static_cast<void> (0));
561 unsigned LHSMask = MaskPair->first;
562 unsigned RHSMask = MaskPair->second;
563 unsigned Mask = LHSMask & RHSMask;
564 if (Mask == 0) {
565 // Even if the two sides don't share a common pattern, check if folding can
566 // still happen.
567 if (Value *V = foldLogOpOfMaskedICmpsAsymmetric(
568 LHS, RHS, IsAnd, A, B, C, D, E, PredL, PredR, LHSMask, RHSMask,
569 Builder))
570 return V;
571 return nullptr;
572 }
573
574 // In full generality:
575 // (icmp (A & B) Op C) | (icmp (A & D) Op E)
576 // == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ]
577 //
578 // If the latter can be converted into (icmp (A & X) Op Y) then the former is
579 // equivalent to (icmp (A & X) !Op Y).
580 //
581 // Therefore, we can pretend for the rest of this function that we're dealing
582 // with the conjunction, provided we flip the sense of any comparisons (both
583 // input and output).
584
585 // In most cases we're going to produce an EQ for the "&&" case.
586 ICmpInst::Predicate NewCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
587 if (!IsAnd) {
588 // Convert the masking analysis into its equivalent with negated
589 // comparisons.
590 Mask = conjugateICmpMask(Mask);
591 }
592
593 if (Mask & Mask_AllZeros) {
594 // (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
595 // -> (icmp eq (A & (B|D)), 0)
596 Value *NewOr = Builder.CreateOr(B, D);
597 Value *NewAnd = Builder.CreateAnd(A, NewOr);
598 // We can't use C as zero because we might actually handle
599 // (icmp ne (A & B), B) & (icmp ne (A & D), D)
600 // with B and D, having a single bit set.
601 Value *Zero = Constant::getNullValue(A->getType());
602 return Builder.CreateICmp(NewCC, NewAnd, Zero);
603 }
604 if (Mask & BMask_AllOnes) {
605 // (icmp eq (A & B), B) & (icmp eq (A & D), D)
606 // -> (icmp eq (A & (B|D)), (B|D))
607 Value *NewOr = Builder.CreateOr(B, D);
608 Value *NewAnd = Builder.CreateAnd(A, NewOr);
609 return Builder.CreateICmp(NewCC, NewAnd, NewOr);
610 }
611 if (Mask & AMask_AllOnes) {
612 // (icmp eq (A & B), A) & (icmp eq (A & D), A)
613 // -> (icmp eq (A & (B&D)), A)
614 Value *NewAnd1 = Builder.CreateAnd(B, D);
615 Value *NewAnd2 = Builder.CreateAnd(A, NewAnd1);
616 return Builder.CreateICmp(NewCC, NewAnd2, A);
617 }
618
619 // Remaining cases assume at least that B and D are constant, and depend on
620 // their actual values. This isn't strictly necessary, just a "handle the
621 // easy cases for now" decision.
622 ConstantInt *BCst, *DCst;
623 if (!match(B, m_ConstantInt(BCst)) || !match(D, m_ConstantInt(DCst)))
624 return nullptr;
625
626 if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) {
627 // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
628 // (icmp ne (A & B), B) & (icmp ne (A & D), D)
629 // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
630 // Only valid if one of the masks is a superset of the other (check "B&D" is
631 // the same as either B or D).
632 APInt NewMask = BCst->getValue() & DCst->getValue();
633
634 if (NewMask == BCst->getValue())
635 return LHS;
636 else if (NewMask == DCst->getValue())
637 return RHS;
638 }
639
640 if (Mask & AMask_NotAllOnes) {
641 // (icmp ne (A & B), B) & (icmp ne (A & D), D)
642 // -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
643 // Only valid if one of the masks is a superset of the other (check "B|D" is
644 // the same as either B or D).
645 APInt NewMask = BCst->getValue() | DCst->getValue();
646
647 if (NewMask == BCst->getValue())
648 return LHS;
649 else if (NewMask == DCst->getValue())
650 return RHS;
651 }
652
653 if (Mask & BMask_Mixed) {
654 // (icmp eq (A & B), C) & (icmp eq (A & D), E)
655 // We already know that B & C == C && D & E == E.
656 // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
657 // C and E, which are shared by both the mask B and the mask D, don't
658 // contradict, then we can transform to
659 // -> (icmp eq (A & (B|D)), (C|E))
660 // Currently, we only handle the case of B, C, D, and E being constant.
661 // We can't simply use C and E because we might actually handle
662 // (icmp ne (A & B), B) & (icmp eq (A & D), D)
663 // with B and D, having a single bit set.
664 ConstantInt *CCst, *ECst;
665 if (!match(C, m_ConstantInt(CCst)) || !match(E, m_ConstantInt(ECst)))
666 return nullptr;
667 if (PredL != NewCC)
668 CCst = cast<ConstantInt>(ConstantExpr::getXor(BCst, CCst));
669 if (PredR != NewCC)
670 ECst = cast<ConstantInt>(ConstantExpr::getXor(DCst, ECst));
671
672 // If there is a conflict, we should actually return a false for the
673 // whole construct.
674 if (((BCst->getValue() & DCst->getValue()) &
675 (CCst->getValue() ^ ECst->getValue())).getBoolValue())
676 return ConstantInt::get(LHS->getType(), !IsAnd);
677
678 Value *NewOr1 = Builder.CreateOr(B, D);
679 Value *NewOr2 = ConstantExpr::getOr(CCst, ECst);
680 Value *NewAnd = Builder.CreateAnd(A, NewOr1);
681 return Builder.CreateICmp(NewCC, NewAnd, NewOr2);
682 }
683
684 return nullptr;
685}
686
687/// Try to fold a signed range checked with lower bound 0 to an unsigned icmp.
688/// Example: (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
689/// If \p Inverted is true then the check is for the inverted range, e.g.
690/// (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
691Value *InstCombinerImpl::simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1,
692 bool Inverted) {
693 // Check the lower range comparison, e.g. x >= 0
694 // InstCombine already ensured that if there is a constant it's on the RHS.
695 ConstantInt *RangeStart = dyn_cast<ConstantInt>(Cmp0->getOperand(1));
696 if (!RangeStart)
697 return nullptr;
698
699 ICmpInst::Predicate Pred0 = (Inverted ? Cmp0->getInversePredicate() :
700 Cmp0->getPredicate());
701
702 // Accept x > -1 or x >= 0 (after potentially inverting the predicate).
703 if (!((Pred0 == ICmpInst::ICMP_SGT && RangeStart->isMinusOne()) ||
704 (Pred0 == ICmpInst::ICMP_SGE && RangeStart->isZero())))
705 return nullptr;
706
707 ICmpInst::Predicate Pred1 = (Inverted ? Cmp1->getInversePredicate() :
708 Cmp1->getPredicate());
709
710 Value *Input = Cmp0->getOperand(0);
711 Value *RangeEnd;
712 if (Cmp1->getOperand(0) == Input) {
713 // For the upper range compare we have: icmp x, n
714 RangeEnd = Cmp1->getOperand(1);
715 } else if (Cmp1->getOperand(1) == Input) {
716 // For the upper range compare we have: icmp n, x
717 RangeEnd = Cmp1->getOperand(0);
718 Pred1 = ICmpInst::getSwappedPredicate(Pred1);
719 } else {
720 return nullptr;
721 }
722
723 // Check the upper range comparison, e.g. x < n
724 ICmpInst::Predicate NewPred;
725 switch (Pred1) {
726 case ICmpInst::ICMP_SLT: NewPred = ICmpInst::ICMP_ULT; break;
727 case ICmpInst::ICMP_SLE: NewPred = ICmpInst::ICMP_ULE; break;
728 default: return nullptr;
729 }
730
731 // This simplification is only valid if the upper range is not negative.
732 KnownBits Known = computeKnownBits(RangeEnd, /*Depth=*/0, Cmp1);
733 if (!Known.isNonNegative())
734 return nullptr;
735
736 if (Inverted)
737 NewPred = ICmpInst::getInversePredicate(NewPred);
738
739 return Builder.CreateICmp(NewPred, Input, RangeEnd);
740}
741
742static Value *
743foldAndOrOfEqualityCmpsWithConstants(ICmpInst *LHS, ICmpInst *RHS,
744 bool JoinedByAnd,
745 InstCombiner::BuilderTy &Builder) {
746 Value *X = LHS->getOperand(0);
747 if (X != RHS->getOperand(0))
748 return nullptr;
749
750 const APInt *C1, *C2;
751 if (!match(LHS->getOperand(1), m_APInt(C1)) ||
752 !match(RHS->getOperand(1), m_APInt(C2)))
753 return nullptr;
754
755 // We only handle (X != C1 && X != C2) and (X == C1 || X == C2).
756 ICmpInst::Predicate Pred = LHS->getPredicate();
757 if (Pred != RHS->getPredicate())
758 return nullptr;
759 if (JoinedByAnd && Pred != ICmpInst::ICMP_NE)
760 return nullptr;
761 if (!JoinedByAnd && Pred != ICmpInst::ICMP_EQ)
762 return nullptr;
763
764 // The larger unsigned constant goes on the right.
765 if (C1->ugt(*C2))
766 std::swap(C1, C2);
767
768 APInt Xor = *C1 ^ *C2;
769 if (Xor.isPowerOf2()) {
770 // If LHSC and RHSC differ by only one bit, then set that bit in X and
771 // compare against the larger constant:
772 // (X == C1 || X == C2) --> (X | (C1 ^ C2)) == C2
773 // (X != C1 && X != C2) --> (X | (C1 ^ C2)) != C2
774 // We choose an 'or' with a Pow2 constant rather than the inverse mask with
775 // 'and' because that may lead to smaller codegen from a smaller constant.
776 Value *Or = Builder.CreateOr(X, ConstantInt::get(X->getType(), Xor));
777 return Builder.CreateICmp(Pred, Or, ConstantInt::get(X->getType(), *C2));
778 }
779
780 // Special case: get the ordering right when the values wrap around zero.
781 // Ie, we assumed the constants were unsigned when swapping earlier.
782 if (C1->isNullValue() && C2->isAllOnesValue())
783 std::swap(C1, C2);
784
785 if (*C1 == *C2 - 1) {
786 // (X == 13 || X == 14) --> X - 13 <=u 1
787 // (X != 13 && X != 14) --> X - 13 >u 1
788 // An 'add' is the canonical IR form, so favor that over a 'sub'.
789 Value *Add = Builder.CreateAdd(X, ConstantInt::get(X->getType(), -(*C1)));
790 auto NewPred = JoinedByAnd ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_ULE;
791 return Builder.CreateICmp(NewPred, Add, ConstantInt::get(X->getType(), 1));
792 }
793
794 return nullptr;
795}
796
797// Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
798// Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2)
799Value *InstCombinerImpl::foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS,
800 ICmpInst *RHS,
801 Instruction *CxtI,
802 bool IsAnd,
803 bool IsLogical) {
804 CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ;
805 if (LHS->getPredicate() != Pred || RHS->getPredicate() != Pred)
806 return nullptr;
807
808 if (!match(LHS->getOperand(1), m_Zero()) ||
809 !match(RHS->getOperand(1), m_Zero()))
810 return nullptr;
811
812 Value *L1, *L2, *R1, *R2;
813 if (match(LHS->getOperand(0), m_And(m_Value(L1), m_Value(L2))) &&
814 match(RHS->getOperand(0), m_And(m_Value(R1), m_Value(R2)))) {
815 if (L1 == R2 || L2 == R2)
816 std::swap(R1, R2);
817 if (L2 == R1)
818 std::swap(L1, L2);
819
820 if (L1 == R1 &&
821 isKnownToBeAPowerOfTwo(L2, false, 0, CxtI) &&
822 isKnownToBeAPowerOfTwo(R2, false, 0, CxtI)) {
823 // If this is a logical and/or, then we must prevent propagation of a
824 // poison value from the RHS by inserting freeze.
825 if (IsLogical)
826 R2 = Builder.CreateFreeze(R2);
827 Value *Mask = Builder.CreateOr(L2, R2);
828 Value *Masked = Builder.CreateAnd(L1, Mask);
829 auto NewPred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::ICMP_NE;
830 return Builder.CreateICmp(NewPred, Masked, Mask);
831 }
832 }
833
834 return nullptr;
835}
836
837/// General pattern:
838/// X & Y
839///
840/// Where Y is checking that all the high bits (covered by a mask 4294967168)
841/// are uniform, i.e. %arg & 4294967168 can be either 4294967168 or 0
842/// Pattern can be one of:
843/// %t = add i32 %arg, 128
844/// %r = icmp ult i32 %t, 256
845/// Or
846/// %t0 = shl i32 %arg, 24
847/// %t1 = ashr i32 %t0, 24
848/// %r = icmp eq i32 %t1, %arg
849/// Or
850/// %t0 = trunc i32 %arg to i8
851/// %t1 = sext i8 %t0 to i32
852/// %r = icmp eq i32 %t1, %arg
853/// This pattern is a signed truncation check.
854///
855/// And X is checking that some bit in that same mask is zero.
856/// I.e. can be one of:
857/// %r = icmp sgt i32 %arg, -1
858/// Or
859/// %t = and i32 %arg, 2147483648
860/// %r = icmp eq i32 %t, 0
861///
862/// Since we are checking that all the bits in that mask are the same,
863/// and a particular bit is zero, what we are really checking is that all the
864/// masked bits are zero.
865/// So this should be transformed to:
866/// %r = icmp ult i32 %arg, 128
867static Value *foldSignedTruncationCheck(ICmpInst *ICmp0, ICmpInst *ICmp1,
868 Instruction &CxtI,
869 InstCombiner::BuilderTy &Builder) {
870 assert(CxtI.getOpcode() == Instruction::And)(static_cast<void> (0));
871
872 // Match icmp ult (add %arg, C01), C1 (C1 == C01 << 1; powers of two)
873 auto tryToMatchSignedTruncationCheck = [](ICmpInst *ICmp, Value *&X,
874 APInt &SignBitMask) -> bool {
875 CmpInst::Predicate Pred;
876 const APInt *I01, *I1; // powers of two; I1 == I01 << 1
877 if (!(match(ICmp,
878 m_ICmp(Pred, m_Add(m_Value(X), m_Power2(I01)), m_Power2(I1))) &&
879 Pred == ICmpInst::ICMP_ULT && I1->ugt(*I01) && I01->shl(1) == *I1))
880 return false;
881 // Which bit is the new sign bit as per the 'signed truncation' pattern?
882 SignBitMask = *I01;
883 return true;
884 };
885
886 // One icmp needs to be 'signed truncation check'.
887 // We need to match this first, else we will mismatch commutative cases.
888 Value *X1;
889 APInt HighestBit;
890 ICmpInst *OtherICmp;
891 if (tryToMatchSignedTruncationCheck(ICmp1, X1, HighestBit))
892 OtherICmp = ICmp0;
893 else if (tryToMatchSignedTruncationCheck(ICmp0, X1, HighestBit))
894 OtherICmp = ICmp1;
895 else
896 return nullptr;
897
898 assert(HighestBit.isPowerOf2() && "expected to be power of two (non-zero)")(static_cast<void> (0));
899
900 // Try to match/decompose into: icmp eq (X & Mask), 0
901 auto tryToDecompose = [](ICmpInst *ICmp, Value *&X,
902 APInt &UnsetBitsMask) -> bool {
903 CmpInst::Predicate Pred = ICmp->getPredicate();
904 // Can it be decomposed into icmp eq (X & Mask), 0 ?
905 if (llvm::decomposeBitTestICmp(ICmp->getOperand(0), ICmp->getOperand(1),
906 Pred, X, UnsetBitsMask,
907 /*LookThroughTrunc=*/false) &&
908 Pred == ICmpInst::ICMP_EQ)
909 return true;
910 // Is it icmp eq (X & Mask), 0 already?
911 const APInt *Mask;
912 if (match(ICmp, m_ICmp(Pred, m_And(m_Value(X), m_APInt(Mask)), m_Zero())) &&
913 Pred == ICmpInst::ICMP_EQ) {
914 UnsetBitsMask = *Mask;
915 return true;
916 }
917 return false;
918 };
919
920 // And the other icmp needs to be decomposable into a bit test.
921 Value *X0;
922 APInt UnsetBitsMask;
923 if (!tryToDecompose(OtherICmp, X0, UnsetBitsMask))
924 return nullptr;
925
926 assert(!UnsetBitsMask.isNullValue() && "empty mask makes no sense.")(static_cast<void> (0));
927
928 // Are they working on the same value?
929 Value *X;
930 if (X1 == X0) {
931 // Ok as is.
932 X = X1;
933 } else if (match(X0, m_Trunc(m_Specific(X1)))) {
934 UnsetBitsMask = UnsetBitsMask.zext(X1->getType()->getScalarSizeInBits());
935 X = X1;
936 } else
937 return nullptr;
938
939 // So which bits should be uniform as per the 'signed truncation check'?
940 // (all the bits starting with (i.e. including) HighestBit)
941 APInt SignBitsMask = ~(HighestBit - 1U);
942
943 // UnsetBitsMask must have some common bits with SignBitsMask,
944 if (!UnsetBitsMask.intersects(SignBitsMask))
945 return nullptr;
946
947 // Does UnsetBitsMask contain any bits outside of SignBitsMask?
948 if (!UnsetBitsMask.isSubsetOf(SignBitsMask)) {
949 APInt OtherHighestBit = (~UnsetBitsMask) + 1U;
950 if (!OtherHighestBit.isPowerOf2())
951 return nullptr;
952 HighestBit = APIntOps::umin(HighestBit, OtherHighestBit);
953 }
954 // Else, if it does not, then all is ok as-is.
955
956 // %r = icmp ult %X, SignBit
957 return Builder.CreateICmpULT(X, ConstantInt::get(X->getType(), HighestBit),
958 CxtI.getName() + ".simplified");
959}
960
961/// Reduce a pair of compares that check if a value has exactly 1 bit set.
962static Value *foldIsPowerOf2(ICmpInst *Cmp0, ICmpInst *Cmp1, bool JoinedByAnd,
963 InstCombiner::BuilderTy &Builder) {
964 // Handle 'and' / 'or' commutation: make the equality check the first operand.
965 if (JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_NE)
966 std::swap(Cmp0, Cmp1);
967 else if (!JoinedByAnd && Cmp1->getPredicate() == ICmpInst::ICMP_EQ)
968 std::swap(Cmp0, Cmp1);
969
970 // (X != 0) && (ctpop(X) u< 2) --> ctpop(X) == 1
971 CmpInst::Predicate Pred0, Pred1;
972 Value *X;
973 if (JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) &&
974 match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)),
975 m_SpecificInt(2))) &&
976 Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT) {
977 Value *CtPop = Cmp1->getOperand(0);
978 return Builder.CreateICmpEQ(CtPop, ConstantInt::get(CtPop->getType(), 1));
979 }
980 // (X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1
981 if (!JoinedByAnd && match(Cmp0, m_ICmp(Pred0, m_Value(X), m_ZeroInt())) &&
982 match(Cmp1, m_ICmp(Pred1, m_Intrinsic<Intrinsic::ctpop>(m_Specific(X)),
983 m_SpecificInt(1))) &&
984 Pred0 == ICmpInst::ICMP_EQ && Pred1 == ICmpInst::ICMP_UGT) {
985 Value *CtPop = Cmp1->getOperand(0);
986 return Builder.CreateICmpNE(CtPop, ConstantInt::get(CtPop->getType(), 1));
987 }
988 return nullptr;
989}
990
991/// Commuted variants are assumed to be handled by calling this function again
992/// with the parameters swapped.
993static Value *foldUnsignedUnderflowCheck(ICmpInst *ZeroICmp,
994 ICmpInst *UnsignedICmp, bool IsAnd,
995 const SimplifyQuery &Q,
996 InstCombiner::BuilderTy &Builder) {
997 Value *ZeroCmpOp;
998 ICmpInst::Predicate EqPred;
999 if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(ZeroCmpOp), m_Zero())) ||
1000 !ICmpInst::isEquality(EqPred))
1001 return nullptr;
1002
1003 auto IsKnownNonZero = [&](Value *V) {
1004 return isKnownNonZero(V, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
1005 };
1006
1007 ICmpInst::Predicate UnsignedPred;
1008
1009 Value *A, *B;
1010 if (match(UnsignedICmp,
1011 m_c_ICmp(UnsignedPred, m_Specific(ZeroCmpOp), m_Value(A))) &&
1012 match(ZeroCmpOp, m_c_Add(m_Specific(A), m_Value(B))) &&
1013 (ZeroICmp->hasOneUse() || UnsignedICmp->hasOneUse())) {
1014 auto GetKnownNonZeroAndOther = [&](Value *&NonZero, Value *&Other) {
1015 if (!IsKnownNonZero(NonZero))
1016 std::swap(NonZero, Other);
1017 return IsKnownNonZero(NonZero);
1018 };
1019
1020 // Given ZeroCmpOp = (A + B)
1021 // ZeroCmpOp <= A && ZeroCmpOp != 0 --> (0-B) < A
1022 // ZeroCmpOp > A || ZeroCmpOp == 0 --> (0-B) >= A
1023 //
1024 // ZeroCmpOp < A && ZeroCmpOp != 0 --> (0-X) < Y iff
1025 // ZeroCmpOp >= A || ZeroCmpOp == 0 --> (0-X) >= Y iff
1026 // with X being the value (A/B) that is known to be non-zero,
1027 // and Y being remaining value.
1028 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
1029 IsAnd)
1030 return Builder.CreateICmpULT(Builder.CreateNeg(B), A);
1031 if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE &&
1032 IsAnd && GetKnownNonZeroAndOther(B, A))
1033 return Builder.CreateICmpULT(Builder.CreateNeg(B), A);
1034 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
1035 !IsAnd)
1036 return Builder.CreateICmpUGE(Builder.CreateNeg(B), A);
1037 if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ &&
1038 !IsAnd && GetKnownNonZeroAndOther(B, A))
1039 return Builder.CreateICmpUGE(Builder.CreateNeg(B), A);
1040 }
1041
1042 Value *Base, *Offset;
1043 if (!match(ZeroCmpOp, m_Sub(m_Value(Base), m_Value(Offset))))
1044 return nullptr;
1045
1046 if (!match(UnsignedICmp,
1047 m_c_ICmp(UnsignedPred, m_Specific(Base), m_Specific(Offset))) ||
1048 !ICmpInst::isUnsigned(UnsignedPred))
1049 return nullptr;
1050
1051 // Base >=/> Offset && (Base - Offset) != 0 <--> Base > Offset
1052 // (no overflow and not null)
1053 if ((UnsignedPred == ICmpInst::ICMP_UGE ||
1054 UnsignedPred == ICmpInst::ICMP_UGT) &&
1055 EqPred == ICmpInst::ICMP_NE && IsAnd)
1056 return Builder.CreateICmpUGT(Base, Offset);
1057
1058 // Base <=/< Offset || (Base - Offset) == 0 <--> Base <= Offset
1059 // (overflow or null)
1060 if ((UnsignedPred == ICmpInst::ICMP_ULE ||
1061 UnsignedPred == ICmpInst::ICMP_ULT) &&
1062 EqPred == ICmpInst::ICMP_EQ && !IsAnd)
1063 return Builder.CreateICmpULE(Base, Offset);
1064
1065 // Base <= Offset && (Base - Offset) != 0 --> Base < Offset
1066 if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
1067 IsAnd)
1068 return Builder.CreateICmpULT(Base, Offset);
1069
1070 // Base > Offset || (Base - Offset) == 0 --> Base >= Offset
1071 if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
1072 !IsAnd)
1073 return Builder.CreateICmpUGE(Base, Offset);
1074
1075 return nullptr;
1076}
1077
1078struct IntPart {
1079 Value *From;
1080 unsigned StartBit;
1081 unsigned NumBits;
1082};
1083
1084/// Match an extraction of bits from an integer.
1085static Optional<IntPart> matchIntPart(Value *V) {
1086 Value *X;
1087 if (!match(V, m_OneUse(m_Trunc(m_Value(X)))))
1088 return None;
1089
1090 unsigned NumOriginalBits = X->getType()->getScalarSizeInBits();
1091 unsigned NumExtractedBits = V->getType()->getScalarSizeInBits();
1092 Value *Y;
1093 const APInt *Shift;
1094 // For a trunc(lshr Y, Shift) pattern, make sure we're only extracting bits
1095 // from Y, not any shifted-in zeroes.
1096 if (match(X, m_OneUse(m_LShr(m_Value(Y), m_APInt(Shift)))) &&
1097 Shift->ule(NumOriginalBits - NumExtractedBits))
1098 return {{Y, (unsigned)Shift->getZExtValue(), NumExtractedBits}};
1099 return {{X, 0, NumExtractedBits}};
1100}
1101
1102/// Materialize an extraction of bits from an integer in IR.
1103static Value *extractIntPart(const IntPart &P, IRBuilderBase &Builder) {
1104 Value *V = P.From;
1105 if (P.StartBit)
1106 V = Builder.CreateLShr(V, P.StartBit);
1107 Type *TruncTy = V->getType()->getWithNewBitWidth(P.NumBits);
1108 if (TruncTy != V->getType())
1109 V = Builder.CreateTrunc(V, TruncTy);
1110 return V;
1111}
1112
1113/// (icmp eq X0, Y0) & (icmp eq X1, Y1) -> icmp eq X01, Y01
1114/// (icmp ne X0, Y0) | (icmp ne X1, Y1) -> icmp ne X01, Y01
1115/// where X0, X1 and Y0, Y1 are adjacent parts extracted from an integer.
1116Value *InstCombinerImpl::foldEqOfParts(ICmpInst *Cmp0, ICmpInst *Cmp1,
1117 bool IsAnd) {
1118 if (!Cmp0->hasOneUse() || !Cmp1->hasOneUse())
1119 return nullptr;
1120
1121 CmpInst::Predicate Pred = IsAnd ? CmpInst::ICMP_EQ : CmpInst::ICMP_NE;
1122 if (Cmp0->getPredicate() != Pred || Cmp1->getPredicate() != Pred)
1123 return nullptr;
1124
1125 Optional<IntPart> L0 = matchIntPart(Cmp0->getOperand(0));
1126 Optional<IntPart> R0 = matchIntPart(Cmp0->getOperand(1));
1127 Optional<IntPart> L1 = matchIntPart(Cmp1->getOperand(0));
1128 Optional<IntPart> R1 = matchIntPart(Cmp1->getOperand(1));
1129 if (!L0 || !R0 || !L1 || !R1)
1130 return nullptr;
1131
1132 // Make sure the LHS/RHS compare a part of the same value, possibly after
1133 // an operand swap.
1134 if (L0->From != L1->From || R0->From != R1->From) {
1135 if (L0->From != R1->From || R0->From != L1->From)
1136 return nullptr;
1137 std::swap(L1, R1);
1138 }
1139
1140 // Make sure the extracted parts are adjacent, canonicalizing to L0/R0 being
1141 // the low part and L1/R1 being the high part.
1142 if (L0->StartBit + L0->NumBits != L1->StartBit ||
1143 R0->StartBit + R0->NumBits != R1->StartBit) {
1144 if (L1->StartBit + L1->NumBits != L0->StartBit ||
1145 R1->StartBit + R1->NumBits != R0->StartBit)
1146 return nullptr;
1147 std::swap(L0, L1);
1148 std::swap(R0, R1);
1149 }
1150
1151 // We can simplify to a comparison of these larger parts of the integers.
1152 IntPart L = {L0->From, L0->StartBit, L0->NumBits + L1->NumBits};
1153 IntPart R = {R0->From, R0->StartBit, R0->NumBits + R1->NumBits};
1154 Value *LValue = extractIntPart(L, Builder);
1155 Value *RValue = extractIntPart(R, Builder);
1156 return Builder.CreateICmp(Pred, LValue, RValue);
1157}
1158
1159/// Reduce logic-of-compares with equality to a constant by substituting a
1160/// common operand with the constant. Callers are expected to call this with
1161/// Cmp0/Cmp1 switched to handle logic op commutativity.
1162static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
1163 BinaryOperator &Logic,
1164 InstCombiner::BuilderTy &Builder,
1165 const SimplifyQuery &Q) {
1166 bool IsAnd = Logic.getOpcode() == Instruction::And;
1167 assert((IsAnd || Logic.getOpcode() == Instruction::Or) && "Wrong logic op")(static_cast<void> (0));
1168
1169 // Match an equality compare with a non-poison constant as Cmp0.
1170 // Also, give up if the compare can be constant-folded to avoid looping.
1171 ICmpInst::Predicate Pred0;
1172 Value *X;
1173 Constant *C;
1174 if (!match(Cmp0, m_ICmp(Pred0, m_Value(X), m_Constant(C))) ||
1175 !isGuaranteedNotToBeUndefOrPoison(C) || isa<Constant>(X))
1176 return nullptr;
1177 if ((IsAnd && Pred0 != ICmpInst::ICMP_EQ) ||
1178 (!IsAnd && Pred0 != ICmpInst::ICMP_NE))
1179 return nullptr;
1180
1181 // The other compare must include a common operand (X). Canonicalize the
1182 // common operand as operand 1 (Pred1 is swapped if the common operand was
1183 // operand 0).
1184 Value *Y;
1185 ICmpInst::Predicate Pred1;
1186 if (!match(Cmp1, m_c_ICmp(Pred1, m_Value(Y), m_Deferred(X))))
1187 return nullptr;
1188
1189 // Replace variable with constant value equivalence to remove a variable use:
1190 // (X == C) && (Y Pred1 X) --> (X == C) && (Y Pred1 C)
1191 // (X != C) || (Y Pred1 X) --> (X != C) || (Y Pred1 C)
1192 // Can think of the 'or' substitution with the 'and' bool equivalent:
1193 // A || B --> A || (!A && B)
1194 Value *SubstituteCmp = SimplifyICmpInst(Pred1, Y, C, Q);
1195 if (!SubstituteCmp) {
1196 // If we need to create a new instruction, require that the old compare can
1197 // be removed.
1198 if (!Cmp1->hasOneUse())
1199 return nullptr;
1200 SubstituteCmp = Builder.CreateICmp(Pred1, Y, C);
1201 }
1202 return Builder.CreateBinOp(Logic.getOpcode(), Cmp0, SubstituteCmp);
1203}
1204
1205/// Fold (icmp)&(icmp) if possible.
1206Value *InstCombinerImpl::foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS,
1207 BinaryOperator &And) {
1208 const SimplifyQuery Q = SQ.getWithInstruction(&And);
1209
1210 // Fold (!iszero(A & K1) & !iszero(A & K2)) -> (A & (K1 | K2)) == (K1 | K2)
1211 // if K1 and K2 are a one-bit mask.
1212 if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, &And,
1213 /* IsAnd */ true))
1214 return V;
1215
1216 ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1217
1218 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
1219 if (predicatesFoldable(PredL, PredR)) {
1220 if (LHS->getOperand(0) == RHS->getOperand(1) &&
1221 LHS->getOperand(1) == RHS->getOperand(0))
1222 LHS->swapOperands();
1223 if (LHS->getOperand(0) == RHS->getOperand(0) &&
1224 LHS->getOperand(1) == RHS->getOperand(1)) {
1225 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
1226 unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
1227 bool IsSigned = LHS->isSigned() || RHS->isSigned();
1228 return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder);
1229 }
1230 }
1231
1232 // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E)
1233 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder))
1234 return V;
1235
1236 if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, And, Builder, Q))
1237 return V;
1238 if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, And, Builder, Q))
1239 return V;
1240
1241 // E.g. (icmp sge x, 0) & (icmp slt x, n) --> icmp ult x, n
1242 if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/false))
1243 return V;
1244
1245 // E.g. (icmp slt x, n) & (icmp sge x, 0) --> icmp ult x, n
1246 if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/false))
1247 return V;
1248
1249 if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, true, Builder))
1250 return V;
1251
1252 if (Value *V = foldSignedTruncationCheck(LHS, RHS, And, Builder))
1253 return V;
1254
1255 if (Value *V = foldIsPowerOf2(LHS, RHS, true /* JoinedByAnd */, Builder))
1256 return V;
1257
1258 if (Value *X =
1259 foldUnsignedUnderflowCheck(LHS, RHS, /*IsAnd=*/true, Q, Builder))
1260 return X;
1261 if (Value *X =
1262 foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/true, Q, Builder))
1263 return X;
1264
1265 if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/true))
1266 return X;
1267
1268 // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
1269 Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
1270
1271 ConstantInt *LHSC, *RHSC;
1272 if (!match(LHS->getOperand(1), m_ConstantInt(LHSC)) ||
1273 !match(RHS->getOperand(1), m_ConstantInt(RHSC)))
1274 return nullptr;
1275
1276 if (LHSC == RHSC && PredL == PredR) {
1277 // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
1278 // where C is a power of 2 or
1279 // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
1280 if ((PredL == ICmpInst::ICMP_ULT && LHSC->getValue().isPowerOf2()) ||
1281 (PredL == ICmpInst::ICMP_EQ && LHSC->isZero())) {
1282 Value *NewOr = Builder.CreateOr(LHS0, RHS0);
1283 return Builder.CreateICmp(PredL, NewOr, LHSC);
1284 }
1285 }
1286
1287 // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
1288 // where CMAX is the all ones value for the truncated type,
1289 // iff the lower bits of C2 and CA are zero.
1290 if (PredL == ICmpInst::ICMP_EQ && PredL == PredR && LHS->hasOneUse() &&
1291 RHS->hasOneUse()) {
1292 Value *V;
1293 ConstantInt *AndC, *SmallC = nullptr, *BigC = nullptr;
1294
1295 // (trunc x) == C1 & (and x, CA) == C2
1296 // (and x, CA) == C2 & (trunc x) == C1
1297 if (match(RHS0, m_Trunc(m_Value(V))) &&
1298 match(LHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) {
1299 SmallC = RHSC;
1300 BigC = LHSC;
1301 } else if (match(LHS0, m_Trunc(m_Value(V))) &&
1302 match(RHS0, m_And(m_Specific(V), m_ConstantInt(AndC)))) {
1303 SmallC = LHSC;
1304 BigC = RHSC;
1305 }
1306
1307 if (SmallC && BigC) {
1308 unsigned BigBitSize = BigC->getType()->getBitWidth();
1309 unsigned SmallBitSize = SmallC->getType()->getBitWidth();
1310
1311 // Check that the low bits are zero.
1312 APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
1313 if ((Low & AndC->getValue()).isNullValue() &&
1314 (Low & BigC->getValue()).isNullValue()) {
1315 Value *NewAnd = Builder.CreateAnd(V, Low | AndC->getValue());
1316 APInt N = SmallC->getValue().zext(BigBitSize) | BigC->getValue();
1317 Value *NewVal = ConstantInt::get(AndC->getType()->getContext(), N);
1318 return Builder.CreateICmp(PredL, NewAnd, NewVal);
1319 }
1320 }
1321 }
1322
1323 // From here on, we only handle:
1324 // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
1325 if (LHS0 != RHS0)
1326 return nullptr;
1327
1328 // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
1329 if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
1330 PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
1331 PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
1332 PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
1333 return nullptr;
1334
1335 // We can't fold (ugt x, C) & (sgt x, C2).
1336 if (!predicatesFoldable(PredL, PredR))
1337 return nullptr;
1338
1339 // Ensure that the larger constant is on the RHS.
1340 bool ShouldSwap;
1341 if (CmpInst::isSigned(PredL) ||
1342 (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
1343 ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
1344 else
1345 ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
1346
1347 if (ShouldSwap) {
1348 std::swap(LHS, RHS);
1349 std::swap(LHSC, RHSC);
1350 std::swap(PredL, PredR);
1351 }
1352
1353 // At this point, we know we have two icmp instructions
1354 // comparing a value against two constants and and'ing the result
1355 // together. Because of the above check, we know that we only have
1356 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
1357 // (from the icmp folding check above), that the two constants
1358 // are not equal and that the larger constant is on the RHS
1359 assert(LHSC != RHSC && "Compares not folded above?")(static_cast<void> (0));
1360
1361 switch (PredL) {
1362 default:
1363 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
1364 case ICmpInst::ICMP_NE:
1365 switch (PredR) {
1366 default:
1367 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
1368 case ICmpInst::ICMP_ULT:
1369 // (X != 13 & X u< 14) -> X < 13
1370 if (LHSC->getValue() == (RHSC->getValue() - 1))
1371 return Builder.CreateICmpULT(LHS0, LHSC);
1372 if (LHSC->isZero()) // (X != 0 & X u< C) -> X-1 u< C-1
1373 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
1374 false, true);
1375 break; // (X != 13 & X u< 15) -> no change
1376 case ICmpInst::ICMP_SLT:
1377 // (X != 13 & X s< 14) -> X < 13
1378 if (LHSC->getValue() == (RHSC->getValue() - 1))
1379 return Builder.CreateICmpSLT(LHS0, LHSC);
1380 // (X != INT_MIN & X s< C) -> X-(INT_MIN+1) u< (C-(INT_MIN+1))
1381 if (LHSC->isMinValue(true))
1382 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
1383 true, true);
1384 break; // (X != 13 & X s< 15) -> no change
1385 case ICmpInst::ICMP_NE:
1386 // Potential folds for this case should already be handled.
1387 break;
1388 }
1389 break;
1390 case ICmpInst::ICMP_UGT:
1391 switch (PredR) {
1392 default:
1393 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
1394 case ICmpInst::ICMP_NE:
1395 // (X u> 13 & X != 14) -> X u> 14
1396 if (RHSC->getValue() == (LHSC->getValue() + 1))
1397 return Builder.CreateICmp(PredL, LHS0, RHSC);
1398 // X u> C & X != UINT_MAX -> (X-(C+1)) u< UINT_MAX-(C+1)
1399 if (RHSC->isMaxValue(false))
1400 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
1401 false, true);
1402 break; // (X u> 13 & X != 15) -> no change
1403 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) u< 1
1404 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
1405 false, true);
1406 }
1407 break;
1408 case ICmpInst::ICMP_SGT:
1409 switch (PredR) {
1410 default:
1411 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
1412 case ICmpInst::ICMP_NE:
1413 // (X s> 13 & X != 14) -> X s> 14
1414 if (RHSC->getValue() == (LHSC->getValue() + 1))
1415 return Builder.CreateICmp(PredL, LHS0, RHSC);
1416 // X s> C & X != INT_MAX -> (X-(C+1)) u< INT_MAX-(C+1)
1417 if (RHSC->isMaxValue(true))
1418 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(),
1419 true, true);
1420 break; // (X s> 13 & X != 15) -> no change
1421 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) u< 1
1422 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue(), true,
1423 true);
1424 }
1425 break;
1426 }
1427
1428 return nullptr;
1429}
1430
1431Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
1432 bool IsAnd) {
1433 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
1434 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
1435 FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
1436
1437 if (LHS0 == RHS1 && RHS0 == LHS1) {
1438 // Swap RHS operands to match LHS.
1439 PredR = FCmpInst::getSwappedPredicate(PredR);
1440 std::swap(RHS0, RHS1);
1441 }
1442
1443 // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
1444 // Suppose the relation between x and y is R, where R is one of
1445 // U(1000), L(0100), G(0010) or E(0001), and CC0 and CC1 are the bitmasks for
1446 // testing the desired relations.
1447 //
1448 // Since (R & CC0) and (R & CC1) are either R or 0, we actually have this:
1449 // bool(R & CC0) && bool(R & CC1)
1450 // = bool((R & CC0) & (R & CC1))
1451 // = bool(R & (CC0 & CC1)) <= by re-association, commutation, and idempotency
1452 //
1453 // Since (R & CC0) and (R & CC1) are either R or 0, we actually have this:
1454 // bool(R & CC0) || bool(R & CC1)
1455 // = bool((R & CC0) | (R & CC1))
1456 // = bool(R & (CC0 | CC1)) <= by reversed distribution (contribution? ;)
1457 if (LHS0 == RHS0 && LHS1 == RHS1) {
1458 unsigned FCmpCodeL = getFCmpCode(PredL);
1459 unsigned FCmpCodeR = getFCmpCode(PredR);
1460 unsigned NewPred = IsAnd ? FCmpCodeL & FCmpCodeR : FCmpCodeL | FCmpCodeR;
1461 return getFCmpValue(NewPred, LHS0, LHS1, Builder);
1462 }
1463
1464 if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
1465 (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
1466 if (LHS0->getType() != RHS0->getType())
1467 return nullptr;
1468
1469 // FCmp canonicalization ensures that (fcmp ord/uno X, X) and
1470 // (fcmp ord/uno X, C) will be transformed to (fcmp X, +0.0).
1471 if (match(LHS1, m_PosZeroFP()) && match(RHS1, m_PosZeroFP()))
1472 // Ignore the constants because they are obviously not NANs:
1473 // (fcmp ord x, 0.0) & (fcmp ord y, 0.0) -> (fcmp ord x, y)
1474 // (fcmp uno x, 0.0) | (fcmp uno y, 0.0) -> (fcmp uno x, y)
1475 return Builder.CreateFCmp(PredL, LHS0, RHS0);
1476 }
1477
1478 return nullptr;
1479}
1480
1481/// This a limited reassociation for a special case (see above) where we are
1482/// checking if two values are either both NAN (unordered) or not-NAN (ordered).
1483/// This could be handled more generally in '-reassociation', but it seems like
1484/// an unlikely pattern for a large number of logic ops and fcmps.
1485static Instruction *reassociateFCmps(BinaryOperator &BO,
1486 InstCombiner::BuilderTy &Builder) {
1487 Instruction::BinaryOps Opcode = BO.getOpcode();
1488 assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&(static_cast<void> (0))
1489 "Expecting and/or op for fcmp transform")(static_cast<void> (0));
1490
1491 // There are 4 commuted variants of the pattern. Canonicalize operands of this
1492 // logic op so an fcmp is operand 0 and a matching logic op is operand 1.
1493 Value *Op0 = BO.getOperand(0), *Op1 = BO.getOperand(1), *X;
1494 FCmpInst::Predicate Pred;
1495 if (match(Op1, m_FCmp(Pred, m_Value(), m_AnyZeroFP())))
1496 std::swap(Op0, Op1);
1497
1498 // Match inner binop and the predicate for combining 2 NAN checks into 1.
1499 BinaryOperator *BO1;
1500 FCmpInst::Predicate NanPred = Opcode == Instruction::And ? FCmpInst::FCMP_ORD
1501 : FCmpInst::FCMP_UNO;
1502 if (!match(Op0, m_FCmp(Pred, m_Value(X), m_AnyZeroFP())) || Pred != NanPred ||
1503 !match(Op1, m_BinOp(BO1)) || BO1->getOpcode() != Opcode)
1504 return nullptr;
1505
1506 // The inner logic op must have a matching fcmp operand.
1507 Value *BO10 = BO1->getOperand(0), *BO11 = BO1->getOperand(1), *Y;
1508 if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
1509 Pred != NanPred || X->getType() != Y->getType())
1510 std::swap(BO10, BO11);
1511
1512 if (!match(BO10, m_FCmp(Pred, m_Value(Y), m_AnyZeroFP())) ||
1513 Pred != NanPred || X->getType() != Y->getType())
1514 return nullptr;
1515
1516 // and (fcmp ord X, 0), (and (fcmp ord Y, 0), Z) --> and (fcmp ord X, Y), Z
1517 // or (fcmp uno X, 0), (or (fcmp uno Y, 0), Z) --> or (fcmp uno X, Y), Z
1518 Value *NewFCmp = Builder.CreateFCmp(Pred, X, Y);
1519 if (auto *NewFCmpInst = dyn_cast<FCmpInst>(NewFCmp)) {
1520 // Intersect FMF from the 2 source fcmps.
1521 NewFCmpInst->copyIRFlags(Op0);
1522 NewFCmpInst->andIRFlags(BO10);
1523 }
1524 return BinaryOperator::Create(Opcode, NewFCmp, BO11);
1525}
1526
1527/// Match De Morgan's Laws:
1528/// (~A & ~B) == (~(A | B))
1529/// (~A | ~B) == (~(A & B))
1530static Instruction *matchDeMorgansLaws(BinaryOperator &I,
1531 InstCombiner::BuilderTy &Builder) {
1532 auto Opcode = I.getOpcode();
1533 assert((Opcode == Instruction::And || Opcode == Instruction::Or) &&(static_cast<void> (0))
1534 "Trying to match De Morgan's Laws with something other than and/or")(static_cast<void> (0));
1535
1536 // Flip the logic operation.
1537 Opcode = (Opcode == Instruction::And) ? Instruction::Or : Instruction::And;
1538
1539 Value *A, *B;
1540 if (match(I.getOperand(0), m_OneUse(m_Not(m_Value(A)))) &&
1541 match(I.getOperand(1), m_OneUse(m_Not(m_Value(B)))) &&
1542 !InstCombiner::isFreeToInvert(A, A->hasOneUse()) &&
1543 !InstCombiner::isFreeToInvert(B, B->hasOneUse())) {
1544 Value *AndOr = Builder.CreateBinOp(Opcode, A, B, I.getName() + ".demorgan");
1545 return BinaryOperator::CreateNot(AndOr);
1546 }
1547
1548 return nullptr;
1549}
1550
1551bool InstCombinerImpl::shouldOptimizeCast(CastInst *CI) {
1552 Value *CastSrc = CI->getOperand(0);
1553
1554 // Noop casts and casts of constants should be eliminated trivially.
1555 if (CI->getSrcTy() == CI->getDestTy() || isa<Constant>(CastSrc))
1556 return false;
1557
1558 // If this cast is paired with another cast that can be eliminated, we prefer
1559 // to have it eliminated.
1560 if (const auto *PrecedingCI = dyn_cast<CastInst>(CastSrc))
1561 if (isEliminableCastPair(PrecedingCI, CI))
1562 return false;
1563
1564 return true;
1565}
1566
1567/// Fold {and,or,xor} (cast X), C.
1568static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast,
1569 InstCombiner::BuilderTy &Builder) {
1570 Constant *C = dyn_cast<Constant>(Logic.getOperand(1));
1571 if (!C)
1572 return nullptr;
1573
1574 auto LogicOpc = Logic.getOpcode();
1575 Type *DestTy = Logic.getType();
1576 Type *SrcTy = Cast->getSrcTy();
1577
1578 // Move the logic operation ahead of a zext or sext if the constant is
1579 // unchanged in the smaller source type. Performing the logic in a smaller
1580 // type may provide more information to later folds, and the smaller logic
1581 // instruction may be cheaper (particularly in the case of vectors).
1582 Value *X;
1583 if (match(Cast, m_OneUse(m_ZExt(m_Value(X))))) {
1584 Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy);
1585 Constant *ZextTruncC = ConstantExpr::getZExt(TruncC, DestTy);
1586 if (ZextTruncC == C) {
1587 // LogicOpc (zext X), C --> zext (LogicOpc X, C)
1588 Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC);
1589 return new ZExtInst(NewOp, DestTy);
1590 }
1591 }
1592
1593 if (match(Cast, m_OneUse(m_SExt(m_Value(X))))) {
1594 Constant *TruncC = ConstantExpr::getTrunc(C, SrcTy);
1595 Constant *SextTruncC = ConstantExpr::getSExt(TruncC, DestTy);
1596 if (SextTruncC == C) {
1597 // LogicOpc (sext X), C --> sext (LogicOpc X, C)
1598 Value *NewOp = Builder.CreateBinOp(LogicOpc, X, TruncC);
1599 return new SExtInst(NewOp, DestTy);
1600 }
1601 }
1602
1603 return nullptr;
1604}
1605
1606/// Fold {and,or,xor} (cast X), Y.
1607Instruction *InstCombinerImpl::foldCastedBitwiseLogic(BinaryOperator &I) {
1608 auto LogicOpc = I.getOpcode();
1609 assert(I.isBitwiseLogicOp() && "Unexpected opcode for bitwise logic folding")(static_cast<void> (0));
1610
1611 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1612 CastInst *Cast0 = dyn_cast<CastInst>(Op0);
1613 if (!Cast0)
1614 return nullptr;
1615
1616 // This must be a cast from an integer or integer vector source type to allow
1617 // transformation of the logic operation to the source type.
1618 Type *DestTy = I.getType();
1619 Type *SrcTy = Cast0->getSrcTy();
1620 if (!SrcTy->isIntOrIntVectorTy())
1621 return nullptr;
1622
1623 if (Instruction *Ret = foldLogicCastConstant(I, Cast0, Builder))
1624 return Ret;
1625
1626 CastInst *Cast1 = dyn_cast<CastInst>(Op1);
1627 if (!Cast1)
1628 return nullptr;
1629
1630 // Both operands of the logic operation are casts. The casts must be of the
1631 // same type for reduction.
1632 auto CastOpcode = Cast0->getOpcode();
1633 if (CastOpcode != Cast1->getOpcode() || SrcTy != Cast1->getSrcTy())
1634 return nullptr;
1635
1636 Value *Cast0Src = Cast0->getOperand(0);
1637 Value *Cast1Src = Cast1->getOperand(0);
1638
1639 // fold logic(cast(A), cast(B)) -> cast(logic(A, B))
1640 if (shouldOptimizeCast(Cast0) && shouldOptimizeCast(Cast1)) {
1641 Value *NewOp = Builder.CreateBinOp(LogicOpc, Cast0Src, Cast1Src,
1642 I.getName());
1643 return CastInst::Create(CastOpcode, NewOp, DestTy);
1644 }
1645
1646 // For now, only 'and'/'or' have optimizations after this.
1647 if (LogicOpc == Instruction::Xor)
1648 return nullptr;
1649
1650 // If this is logic(cast(icmp), cast(icmp)), try to fold this even if the
1651 // cast is otherwise not optimizable. This happens for vector sexts.
1652 ICmpInst *ICmp0 = dyn_cast<ICmpInst>(Cast0Src);
1653 ICmpInst *ICmp1 = dyn_cast<ICmpInst>(Cast1Src);
1654 if (ICmp0 && ICmp1) {
1655 Value *Res = LogicOpc == Instruction::And ? foldAndOfICmps(ICmp0, ICmp1, I)
1656 : foldOrOfICmps(ICmp0, ICmp1, I);
1657 if (Res)
1658 return CastInst::Create(CastOpcode, Res, DestTy);
1659 return nullptr;
1660 }
1661
1662 // If this is logic(cast(fcmp), cast(fcmp)), try to fold this even if the
1663 // cast is otherwise not optimizable. This happens for vector sexts.
1664 FCmpInst *FCmp0 = dyn_cast<FCmpInst>(Cast0Src);
1665 FCmpInst *FCmp1 = dyn_cast<FCmpInst>(Cast1Src);
1666 if (FCmp0 && FCmp1)
1667 if (Value *R = foldLogicOfFCmps(FCmp0, FCmp1, LogicOpc == Instruction::And))
1668 return CastInst::Create(CastOpcode, R, DestTy);
1669
1670 return nullptr;
1671}
1672
1673static Instruction *foldAndToXor(BinaryOperator &I,
1674 InstCombiner::BuilderTy &Builder) {
1675 assert(I.getOpcode() == Instruction::And)(static_cast<void> (0));
1676 Value *Op0 = I.getOperand(0);
1677 Value *Op1 = I.getOperand(1);
1678 Value *A, *B;
1679
1680 // Operand complexity canonicalization guarantees that the 'or' is Op0.
1681 // (A | B) & ~(A & B) --> A ^ B
1682 // (A | B) & ~(B & A) --> A ^ B
1683 if (match(&I, m_BinOp(m_Or(m_Value(A), m_Value(B)),
1684 m_Not(m_c_And(m_Deferred(A), m_Deferred(B))))))
1685 return BinaryOperator::CreateXor(A, B);
1686
1687 // (A | ~B) & (~A | B) --> ~(A ^ B)
1688 // (A | ~B) & (B | ~A) --> ~(A ^ B)
1689 // (~B | A) & (~A | B) --> ~(A ^ B)
1690 // (~B | A) & (B | ~A) --> ~(A ^ B)
1691 if (Op0->hasOneUse() || Op1->hasOneUse())
1692 if (match(&I, m_BinOp(m_c_Or(m_Value(A), m_Not(m_Value(B))),
1693 m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B)))))
1694 return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
1695
1696 return nullptr;
1697}
1698
1699static Instruction *foldOrToXor(BinaryOperator &I,
1700 InstCombiner::BuilderTy &Builder) {
1701 assert(I.getOpcode() == Instruction::Or)(static_cast<void> (0));
1702 Value *Op0 = I.getOperand(0);
1703 Value *Op1 = I.getOperand(1);
1704 Value *A, *B;
1705
1706 // Operand complexity canonicalization guarantees that the 'and' is Op0.
1707 // (A & B) | ~(A | B) --> ~(A ^ B)
1708 // (A & B) | ~(B | A) --> ~(A ^ B)
1709 if (Op0->hasOneUse() || Op1->hasOneUse())
1710 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
1711 match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
1712 return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
1713
1714 // Operand complexity canonicalization guarantees that the 'xor' is Op0.
1715 // (A ^ B) | ~(A | B) --> ~(A & B)
1716 // (A ^ B) | ~(B | A) --> ~(A & B)
1717 if (Op0->hasOneUse() || Op1->hasOneUse())
1718 if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
1719 match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
1720 return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));
1721
1722 // (A & ~B) | (~A & B) --> A ^ B
1723 // (A & ~B) | (B & ~A) --> A ^ B
1724 // (~B & A) | (~A & B) --> A ^ B
1725 // (~B & A) | (B & ~A) --> A ^ B
1726 if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
1727 match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B))))
1728 return BinaryOperator::CreateXor(A, B);
1729
1730 return nullptr;
1731}
1732
1733/// Return true if a constant shift amount is always less than the specified
1734/// bit-width. If not, the shift could create poison in the narrower type.
1735static bool canNarrowShiftAmt(Constant *C, unsigned BitWidth) {
1736 APInt Threshold(C->getType()->getScalarSizeInBits(), BitWidth);
1737 return match(C, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, Threshold));
1738}
1739
1740/// Try to use narrower ops (sink zext ops) for an 'and' with binop operand and
1741/// a common zext operand: and (binop (zext X), C), (zext X).
1742Instruction *InstCombinerImpl::narrowMaskedBinOp(BinaryOperator &And) {
1743 // This transform could also apply to {or, and, xor}, but there are better
1744 // folds for those cases, so we don't expect those patterns here. AShr is not
1745 // handled because it should always be transformed to LShr in this sequence.
1746 // The subtract transform is different because it has a constant on the left.
1747 // Add/mul commute the constant to RHS; sub with constant RHS becomes add.
1748 Value *Op0 = And.getOperand(0), *Op1 = And.getOperand(1);
1749 Constant *C;
1750 if (!match(Op0, m_OneUse(m_Add(m_Specific(Op1), m_Constant(C)))) &&
1751 !match(Op0, m_OneUse(m_Mul(m_Specific(Op1), m_Constant(C)))) &&
1752 !match(Op0, m_OneUse(m_LShr(m_Specific(Op1), m_Constant(C)))) &&
1753 !match(Op0, m_OneUse(m_Shl(m_Specific(Op1), m_Constant(C)))) &&
1754 !match(Op0, m_OneUse(m_Sub(m_Constant(C), m_Specific(Op1)))))
1755 return nullptr;
1756
1757 Value *X;
1758 if (!match(Op1, m_ZExt(m_Value(X))) || Op1->hasNUsesOrMore(3))
1759 return nullptr;
1760
1761 Type *Ty = And.getType();
1762 if (!isa<VectorType>(Ty) && !shouldChangeType(Ty, X->getType()))
1763 return nullptr;
1764
1765 // If we're narrowing a shift, the shift amount must be safe (less than the
1766 // width) in the narrower type. If the shift amount is greater, instsimplify
1767 // usually handles that case, but we can't guarantee/assert it.
1768 Instruction::BinaryOps Opc = cast<BinaryOperator>(Op0)->getOpcode();
1769 if (Opc == Instruction::LShr || Opc == Instruction::Shl)
1770 if (!canNarrowShiftAmt(C, X->getType()->getScalarSizeInBits()))
1771 return nullptr;
1772
1773 // and (sub C, (zext X)), (zext X) --> zext (and (sub C', X), X)
1774 // and (binop (zext X), C), (zext X) --> zext (and (binop X, C'), X)
1775 Value *NewC = ConstantExpr::getTrunc(C, X->getType());
1776 Value *NewBO = Opc == Instruction::Sub ? Builder.CreateBinOp(Opc, NewC, X)
1777 : Builder.CreateBinOp(Opc, X, NewC);
1778 return new ZExtInst(Builder.CreateAnd(NewBO, X), Ty);
1779}
1780
1781// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
1782// here. We should standardize that construct where it is needed or choose some
1783// other way to ensure that commutated variants of patterns are not missed.
1784Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
1785 Type *Ty = I.getType();
1786
1787 if (Value *V = SimplifyAndInst(I.getOperand(0), I.getOperand(1),
1788 SQ.getWithInstruction(&I)))
1789 return replaceInstUsesWith(I, V);
1790
1791 if (SimplifyAssociativeOrCommutative(I))
1792 return &I;
1793
1794 if (Instruction *X = foldVectorBinop(I))
1795 return X;
1796
1797 // See if we can simplify any instructions used by the instruction whose sole
1798 // purpose is to compute bits we don't care about.
1799 if (SimplifyDemandedInstructionBits(I))
1800 return &I;
1801
1802 // Do this before using distributive laws to catch simple and/or/not patterns.
1803 if (Instruction *Xor = foldAndToXor(I, Builder))
1804 return Xor;
1805
1806 // (A|B)&(A|C) -> A|(B&C) etc
1807 if (Value *V = SimplifyUsingDistributiveLaws(I))
1808 return replaceInstUsesWith(I, V);
1809
1810 if (Value *V = SimplifyBSwap(I, Builder))
1811 return replaceInstUsesWith(I, V);
1812
1813 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1814
1815 Value *X, *Y;
1816 if (match(Op0, m_OneUse(m_LogicalShift(m_One(), m_Value(X)))) &&
1817 match(Op1, m_One())) {
1818 // (1 << X) & 1 --> zext(X == 0)
1819 // (1 >> X) & 1 --> zext(X == 0)
1820 Value *IsZero = Builder.CreateICmpEQ(X, ConstantInt::get(Ty, 0));
1821 return new ZExtInst(IsZero, Ty);
1822 }
1823
1824 const APInt *C;
1825 if (match(Op1, m_APInt(C))) {
1826 const APInt *XorC;
1827 if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_APInt(XorC))))) {
1828 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
1829 Constant *NewC = ConstantInt::get(Ty, *C & *XorC);
1830 Value *And = Builder.CreateAnd(X, Op1);
1831 And->takeName(Op0);
1832 return BinaryOperator::CreateXor(And, NewC);
1833 }
1834
1835 const APInt *OrC;
1836 if (match(Op0, m_OneUse(m_Or(m_Value(X), m_APInt(OrC))))) {
1837 // (X | C1) & C2 --> (X & C2^(C1&C2)) | (C1&C2)
1838 // NOTE: This reduces the number of bits set in the & mask, which
1839 // can expose opportunities for store narrowing for scalars.
1840 // NOTE: SimplifyDemandedBits should have already removed bits from C1
1841 // that aren't set in C2. Meaning we can replace (C1&C2) with C1 in
1842 // above, but this feels safer.
1843 APInt Together = *C & *OrC;
1844 Value *And = Builder.CreateAnd(X, ConstantInt::get(Ty, Together ^ *C));
1845 And->takeName(Op0);
1846 return BinaryOperator::CreateOr(And, ConstantInt::get(Ty, Together));
1847 }
1848
1849 // If the mask is only needed on one incoming arm, push the 'and' op up.
1850 if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_Value(Y)))) ||
1851 match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
1852 APInt NotAndMask(~(*C));
1853 BinaryOperator::BinaryOps BinOp = cast<BinaryOperator>(Op0)->getOpcode();
1854 if (MaskedValueIsZero(X, NotAndMask, 0, &I)) {
1855 // Not masking anything out for the LHS, move mask to RHS.
1856 // and ({x}or X, Y), C --> {x}or X, (and Y, C)
1857 Value *NewRHS = Builder.CreateAnd(Y, Op1, Y->getName() + ".masked");
1858 return BinaryOperator::Create(BinOp, X, NewRHS);
1859 }
1860 if (!isa<Constant>(Y) && MaskedValueIsZero(Y, NotAndMask, 0, &I)) {
1861 // Not masking anything out for the RHS, move mask to LHS.
1862 // and ({x}or X, Y), C --> {x}or (and X, C), Y
1863 Value *NewLHS = Builder.CreateAnd(X, Op1, X->getName() + ".masked");
1864 return BinaryOperator::Create(BinOp, NewLHS, Y);
1865 }
1866 }
1867
1868 unsigned Width = Ty->getScalarSizeInBits();
1869 const APInt *ShiftC;
1870 if (match(Op0, m_OneUse(m_SExt(m_AShr(m_Value(X), m_APInt(ShiftC)))))) {
1871 if (*C == APInt::getLowBitsSet(Width, Width - ShiftC->getZExtValue())) {
1872 // We are clearing high bits that were potentially set by sext+ashr:
1873 // and (sext (ashr X, ShiftC)), C --> lshr (sext X), ShiftC
1874 Value *Sext = Builder.CreateSExt(X, Ty);
1875 Constant *ShAmtC = ConstantInt::get(Ty, ShiftC->zext(Width));
1876 return BinaryOperator::CreateLShr(Sext, ShAmtC);
1877 }
1878 }
1879
1880 const APInt *AddC;
1881 if (match(Op0, m_Add(m_Value(X), m_APInt(AddC)))) {
1882 // If we add zeros to every bit below a mask, the add has no effect:
1883 // (X + AddC) & LowMaskC --> X & LowMaskC
1884 unsigned Ctlz = C->countLeadingZeros();
1885 APInt LowMask(APInt::getLowBitsSet(Width, Width - Ctlz));
1886 if ((*AddC & LowMask).isNullValue())
1887 return BinaryOperator::CreateAnd(X, Op1);
1888
1889 // If we are masking the result of the add down to exactly one bit and
1890 // the constant we are adding has no bits set below that bit, then the
1891 // add is flipping a single bit. Example:
1892 // (X + 4) & 4 --> (X & 4) ^ 4
1893 if (Op0->hasOneUse() && C->isPowerOf2() && (*AddC & (*C - 1)) == 0) {
1894 assert((*C & *AddC) != 0 && "Expected common bit")(static_cast<void> (0));
1895 Value *NewAnd = Builder.CreateAnd(X, Op1);
1896 return BinaryOperator::CreateXor(NewAnd, Op1);
1897 }
1898 }
1899 }
1900
1901 ConstantInt *AndRHS;
1902 if (match(Op1, m_ConstantInt(AndRHS))) {
1903 const APInt &AndRHSMask = AndRHS->getValue();
1904
1905 // Optimize a variety of ((val OP C1) & C2) combinations...
1906 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1907 // ((C1 OP zext(X)) & C2) -> zext((C1-X) & C2) if C2 fits in the bitwidth
1908 // of X and OP behaves well when given trunc(C1) and X.
1909 // TODO: Do this for vectors by using m_APInt instead of m_ConstantInt.
1910 switch (Op0I->getOpcode()) {
1911 default:
1912 break;
1913 case Instruction::Xor:
1914 case Instruction::Or:
1915 case Instruction::Mul:
1916 case Instruction::Add:
1917 case Instruction::Sub:
1918 Value *X;
1919 ConstantInt *C1;
1920 // TODO: The one use restrictions could be relaxed a little if the AND
1921 // is going to be removed.
1922 if (match(Op0I, m_OneUse(m_c_BinOp(m_OneUse(m_ZExt(m_Value(X))),
1923 m_ConstantInt(C1))))) {
1924 if (AndRHSMask.isIntN(X->getType()->getScalarSizeInBits())) {
1925 auto *TruncC1 = ConstantExpr::getTrunc(C1, X->getType());
1926 Value *BinOp;
1927 Value *Op0LHS = Op0I->getOperand(0);
1928 if (isa<ZExtInst>(Op0LHS))
1929 BinOp = Builder.CreateBinOp(Op0I->getOpcode(), X, TruncC1);
1930 else
1931 BinOp = Builder.CreateBinOp(Op0I->getOpcode(), TruncC1, X);
1932 auto *TruncC2 = ConstantExpr::getTrunc(AndRHS, X->getType());
1933 auto *And = Builder.CreateAnd(BinOp, TruncC2);
1934 return new ZExtInst(And, Ty);
1935 }
1936 }
1937 }
1938 }
1939 }
1940
1941 if (match(&I, m_And(m_OneUse(m_Shl(m_ZExt(m_Value(X)), m_Value(Y))),
1942 m_SignMask())) &&
1943 match(Y, m_SpecificInt_ICMP(
1944 ICmpInst::Predicate::ICMP_EQ,
1945 APInt(Ty->getScalarSizeInBits(),
1946 Ty->getScalarSizeInBits() -
1947 X->getType()->getScalarSizeInBits())))) {
1948 auto *SExt = Builder.CreateSExt(X, Ty, X->getName() + ".signext");
1949 auto *SanitizedSignMask = cast<Constant>(Op1);
1950 // We must be careful with the undef elements of the sign bit mask, however:
1951 // the mask elt can be undef iff the shift amount for that lane was undef,
1952 // otherwise we need to sanitize undef masks to zero.
1953 SanitizedSignMask = Constant::replaceUndefsWith(
1954 SanitizedSignMask, ConstantInt::getNullValue(Ty->getScalarType()));
1955 SanitizedSignMask =
1956 Constant::mergeUndefsWith(SanitizedSignMask, cast<Constant>(Y));
1957 return BinaryOperator::CreateAnd(SExt, SanitizedSignMask);
1958 }
1959
1960 if (Instruction *Z = narrowMaskedBinOp(I))
1961 return Z;
1962
1963 if (I.getType()->isIntOrIntVectorTy(1)) {
1964 if (auto *SI0 = dyn_cast<SelectInst>(Op0)) {
1965 if (auto *I =
1966 foldAndOrOfSelectUsingImpliedCond(Op1, *SI0, /* IsAnd */ true))
1967 return I;
1968 }
1969 if (auto *SI1 = dyn_cast<SelectInst>(Op1)) {
1970 if (auto *I =
1971 foldAndOrOfSelectUsingImpliedCond(Op0, *SI1, /* IsAnd */ true))
1972 return I;
1973 }
1974 }
1975
1976 if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
1977 return FoldedLogic;
1978
1979 if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
1980 return DeMorgan;
1981
1982 {
1983 Value *A, *B, *C;
1984 // A & (A ^ B) --> A & ~B
1985 if (match(Op1, m_OneUse(m_c_Xor(m_Specific(Op0), m_Value(B)))))
1986 return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(B));
1987 // (A ^ B) & A --> A & ~B
1988 if (match(Op0, m_OneUse(m_c_Xor(m_Specific(Op1), m_Value(B)))))
1989 return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(B));
1990
1991 // A & ~(A ^ B) --> A & B
1992 if (match(Op1, m_Not(m_c_Xor(m_Specific(Op0), m_Value(B)))))
1993 return BinaryOperator::CreateAnd(Op0, B);
1994 // ~(A ^ B) & A --> A & B
1995 if (match(Op0, m_Not(m_c_Xor(m_Specific(Op1), m_Value(B)))))
1996 return BinaryOperator::CreateAnd(Op1, B);
1997
1998 // (A ^ B) & ((B ^ C) ^ A) -> (A ^ B) & ~C
1999 if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
2000 if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
2001 if (Op1->hasOneUse() || isFreeToInvert(C, C->hasOneUse()))
2002 return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(C));
2003
2004 // ((A ^ C) ^ B) & (B ^ A) -> (B ^ A) & ~C
2005 if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
2006 if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
2007 if (Op0->hasOneUse() || isFreeToInvert(C, C->hasOneUse()))
2008 return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(C));
2009
2010 // (A | B) & ((~A) ^ B) -> (A & B)
2011 // (A | B) & (B ^ (~A)) -> (A & B)
2012 // (B | A) & ((~A) ^ B) -> (A & B)
2013 // (B | A) & (B ^ (~A)) -> (A & B)
2014 if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
2015 match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
2016 return BinaryOperator::CreateAnd(A, B);
2017
2018 // ((~A) ^ B) & (A | B) -> (A & B)
2019 // ((~A) ^ B) & (B | A) -> (A & B)
2020 // (B ^ (~A)) & (A | B) -> (A & B)
2021 // (B ^ (~A)) & (B | A) -> (A & B)
2022 if (match(Op0, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) &&
2023 match(Op1, m_c_Or(m_Specific(A), m_Specific(B))))
2024 return BinaryOperator::CreateAnd(A, B);
2025 }
2026
2027 {
2028 ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
2029 ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
2030 if (LHS && RHS)
2031 if (Value *Res = foldAndOfICmps(LHS, RHS, I))
2032 return replaceInstUsesWith(I, Res);
2033
2034 // TODO: Make this recursive; it's a little tricky because an arbitrary
2035 // number of 'and' instructions might have to be created.
2036 if (LHS && match(Op1, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
2037 if (auto *Cmp = dyn_cast<ICmpInst>(X))
2038 if (Value *Res = foldAndOfICmps(LHS, Cmp, I))
2039 return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y));
2040 if (auto *Cmp = dyn_cast<ICmpInst>(Y))
2041 if (Value *Res = foldAndOfICmps(LHS, Cmp, I))
2042 return replaceInstUsesWith(I, Builder.CreateAnd(Res, X));
2043 }
2044 if (RHS && match(Op0, m_OneUse(m_And(m_Value(X), m_Value(Y))))) {
2045 if (auto *Cmp = dyn_cast<ICmpInst>(X))
2046 if (Value *Res = foldAndOfICmps(Cmp, RHS, I))
2047 return replaceInstUsesWith(I, Builder.CreateAnd(Res, Y));
2048 if (auto *Cmp = dyn_cast<ICmpInst>(Y))
2049 if (Value *Res = foldAndOfICmps(Cmp, RHS, I))
2050 return replaceInstUsesWith(I, Builder.CreateAnd(Res, X));
2051 }
2052 }
2053
2054 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
2055 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
2056 if (Value *Res = foldLogicOfFCmps(LHS, RHS, true))
2057 return replaceInstUsesWith(I, Res);
2058
2059 if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder))
2060 return FoldedFCmps;
2061
2062 if (Instruction *CastedAnd = foldCastedBitwiseLogic(I))
2063 return CastedAnd;
2064
2065 // and(sext(A), B) / and(B, sext(A)) --> A ? B : 0, where A is i1 or <N x i1>.
2066 Value *A;
2067 if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
2068 A->getType()->isIntOrIntVectorTy(1))
2069 return SelectInst::Create(A, Op1, Constant::getNullValue(Ty));
2070 if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
2071 A->getType()->isIntOrIntVectorTy(1))
2072 return SelectInst::Create(A, Op0, Constant::getNullValue(Ty));
2073
2074 // and(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X) --> X s> Y ? X : 0.
2075 if (match(&I, m_c_And(m_OneUse(m_AShr(
2076 m_NSWSub(m_Value(Y), m_Value(X)),
2077 m_SpecificInt(Ty->getScalarSizeInBits() - 1))),
2078 m_Deferred(X)))) {
2079 Value *NewICmpInst = Builder.CreateICmpSGT(X, Y);
2080 return SelectInst::Create(NewICmpInst, X, ConstantInt::getNullValue(Ty));
2081 }
2082
2083 // (~x) & y --> ~(x | (~y)) iff that gets rid of inversions
2084 if (sinkNotIntoOtherHandOfAndOrOr(I))
2085 return &I;
2086
2087 // An and recurrence w/loop invariant step is equivelent to (and start, step)
2088 PHINode *PN = nullptr;
2089 Value *Start = nullptr, *Step = nullptr;
2090 if (matchSimpleRecurrence(&I, PN, Start, Step) && DT.dominates(Step, PN))
2091 return replaceInstUsesWith(I, Builder.CreateAnd(Start, Step));
2092
2093 return nullptr;
2094}
2095
2096Instruction *InstCombinerImpl::matchBSwapOrBitReverse(Instruction &I,
2097 bool MatchBSwaps,
2098 bool MatchBitReversals) {
2099 SmallVector<Instruction *, 4> Insts;
2100 if (!recognizeBSwapOrBitReverseIdiom(&I, MatchBSwaps, MatchBitReversals,
2101 Insts))
2102 return nullptr;
2103 Instruction *LastInst = Insts.pop_back_val();
2104 LastInst->removeFromParent();
2105
2106 for (auto *Inst : Insts)
2107 Worklist.push(Inst);
2108 return LastInst;
2109}
2110
2111/// Match UB-safe variants of the funnel shift intrinsic.
2112static Instruction *matchFunnelShift(Instruction &Or, InstCombinerImpl &IC) {
2113 // TODO: Can we reduce the code duplication between this and the related
2114 // rotate matching code under visitSelect and visitTrunc?
2115 unsigned Width = Or.getType()->getScalarSizeInBits();
2116
2117 // First, find an or'd pair of opposite shifts:
2118 // or (lshr ShVal0, ShAmt0), (shl ShVal1, ShAmt1)
2119 BinaryOperator *Or0, *Or1;
2120 if (!match(Or.getOperand(0), m_BinOp(Or0)) ||
2121 !match(Or.getOperand(1), m_BinOp(Or1)))
2122 return nullptr;
2123
2124 Value *ShVal0, *ShVal1, *ShAmt0, *ShAmt1;
2125 if (!match(Or0, m_OneUse(m_LogicalShift(m_Value(ShVal0), m_Value(ShAmt0)))) ||
2126 !match(Or1, m_OneUse(m_LogicalShift(m_Value(ShVal1), m_Value(ShAmt1)))) ||
2127 Or0->getOpcode() == Or1->getOpcode())
2128 return nullptr;
2129
2130 // Canonicalize to or(shl(ShVal0, ShAmt0), lshr(ShVal1, ShAmt1)).
2131 if (Or0->getOpcode() == BinaryOperator::LShr) {
2132 std::swap(Or0, Or1);
2133 std::swap(ShVal0, ShVal1);
2134 std::swap(ShAmt0, ShAmt1);
2135 }
2136 assert(Or0->getOpcode() == BinaryOperator::Shl &&(static_cast<void> (0))
2137 Or1->getOpcode() == BinaryOperator::LShr &&(static_cast<void> (0))
2138 "Illegal or(shift,shift) pair")(static_cast<void> (0));
2139
2140 // Match the shift amount operands for a funnel shift pattern. This always
2141 // matches a subtraction on the R operand.
2142 auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
2143 // Check for constant shift amounts that sum to the bitwidth.
2144 const APInt *LI, *RI;
2145 if (match(L, m_APIntAllowUndef(LI)) && match(R, m_APIntAllowUndef(RI)))
2146 if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width)
2147 return ConstantInt::get(L->getType(), *LI);
2148
2149 Constant *LC, *RC;
2150 if (match(L, m_Constant(LC)) && match(R, m_Constant(RC)) &&
2151 match(L, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
2152 match(R, m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
2153 match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowUndef(Width)))
2154 return ConstantExpr::mergeUndefsWith(LC, RC);
2155
2156 // (shl ShVal, X) | (lshr ShVal, (Width - x)) iff X < Width.
2157 // We limit this to X < Width in case the backend re-expands the intrinsic,
2158 // and has to reintroduce a shift modulo operation (InstCombine might remove
2159 // it after this fold). This still doesn't guarantee that the final codegen
2160 // will match this original pattern.
2161 if (match(R, m_OneUse(m_Sub(m_SpecificInt(Width), m_Specific(L))))) {
2162 KnownBits KnownL = IC.computeKnownBits(L, /*Depth*/ 0, &Or);
2163 return KnownL.getMaxValue().ult(Width) ? L : nullptr;
2164 }
2165
2166 // For non-constant cases, the following patterns currently only work for
2167 // rotation patterns.
2168 // TODO: Add general funnel-shift compatible patterns.
2169 if (ShVal0 != ShVal1)
2170 return nullptr;
2171
2172 // For non-constant cases we don't support non-pow2 shift masks.
2173 // TODO: Is it worth matching urem as well?
2174 if (!isPowerOf2_32(Width))
2175 return nullptr;
2176
2177 // The shift amount may be masked with negation:
2178 // (shl ShVal, (X & (Width - 1))) | (lshr ShVal, ((-X) & (Width - 1)))
2179 Value *X;
2180 unsigned Mask = Width - 1;
2181 if (match(L, m_And(m_Value(X), m_SpecificInt(Mask))) &&
2182 match(R, m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask))))
2183 return X;
2184
2185 // Similar to above, but the shift amount may be extended after masking,
2186 // so return the extended value as the parameter for the intrinsic.
2187 if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
2188 match(R, m_And(m_Neg(m_ZExt(m_And(m_Specific(X), m_SpecificInt(Mask)))),
2189 m_SpecificInt(Mask))))
2190 return L;
2191
2192 if (match(L, m_ZExt(m_And(m_Value(X), m_SpecificInt(Mask)))) &&
2193 match(R, m_ZExt(m_And(m_Neg(m_Specific(X)), m_SpecificInt(Mask)))))
2194 return L;
2195
2196 return nullptr;
2197 };
2198
2199 Value *ShAmt = matchShiftAmount(ShAmt0, ShAmt1, Width);
2200 bool IsFshl = true; // Sub on LSHR.
2201 if (!ShAmt) {
2202 ShAmt = matchShiftAmount(ShAmt1, ShAmt0, Width);
2203 IsFshl = false; // Sub on SHL.
2204 }
2205 if (!ShAmt)
2206 return nullptr;
2207
2208 Intrinsic::ID IID = IsFshl ? Intrinsic::fshl : Intrinsic::fshr;
2209 Function *F = Intrinsic::getDeclaration(Or.getModule(), IID, Or.getType());
2210 return CallInst::Create(F, {ShVal0, ShVal1, ShAmt});
2211}
2212
2213/// Attempt to combine or(zext(x),shl(zext(y),bw/2) concat packing patterns.
2214static Instruction *matchOrConcat(Instruction &Or,
2215 InstCombiner::BuilderTy &Builder) {
2216 assert(Or.getOpcode() == Instruction::Or && "bswap requires an 'or'")(static_cast<void> (0));
2217 Value *Op0 = Or.getOperand(0), *Op1 = Or.getOperand(1);
2218 Type *Ty = Or.getType();
2219
2220 unsigned Width = Ty->getScalarSizeInBits();
2221 if ((Width & 1) != 0)
2222 return nullptr;
2223 unsigned HalfWidth = Width / 2;
2224
2225 // Canonicalize zext (lower half) to LHS.
2226 if (!isa<ZExtInst>(Op0))
2227 std::swap(Op0, Op1);
2228
2229 // Find lower/upper half.
2230 Value *LowerSrc, *ShlVal, *UpperSrc;
2231 const APInt *C;
2232 if (!match(Op0, m_OneUse(m_ZExt(m_Value(LowerSrc)))) ||
2233 !match(Op1, m_OneUse(m_Shl(m_Value(ShlVal), m_APInt(C)))) ||
2234 !match(ShlVal, m_OneUse(m_ZExt(m_Value(UpperSrc)))))
2235 return nullptr;
2236 if (*C != HalfWidth || LowerSrc->getType() != UpperSrc->getType() ||
2237 LowerSrc->getType()->getScalarSizeInBits() != HalfWidth)
2238 return nullptr;
2239
2240 auto ConcatIntrinsicCalls = [&](Intrinsic::ID id, Value *Lo, Value *Hi) {
2241 Value *NewLower = Builder.CreateZExt(Lo, Ty);
2242 Value *NewUpper = Builder.CreateZExt(Hi, Ty);
2243 NewUpper = Builder.CreateShl(NewUpper, HalfWidth);
2244 Value *BinOp = Builder.CreateOr(NewLower, NewUpper);
2245 Function *F = Intrinsic::getDeclaration(Or.getModule(), id, Ty);
2246 return Builder.CreateCall(F, BinOp);
2247 };
2248
2249 // BSWAP: Push the concat down, swapping the lower/upper sources.
2250 // concat(bswap(x),bswap(y)) -> bswap(concat(x,y))
2251 Value *LowerBSwap, *UpperBSwap;
2252 if (match(LowerSrc, m_BSwap(m_Value(LowerBSwap))) &&
2253 match(UpperSrc, m_BSwap(m_Value(UpperBSwap))))
2254 return ConcatIntrinsicCalls(Intrinsic::bswap, UpperBSwap, LowerBSwap);
2255
2256 // BITREVERSE: Push the concat down, swapping the lower/upper sources.
2257 // concat(bitreverse(x),bitreverse(y)) -> bitreverse(concat(x,y))
2258 Value *LowerBRev, *UpperBRev;
2259 if (match(LowerSrc, m_BitReverse(m_Value(LowerBRev))) &&
2260 match(UpperSrc, m_BitReverse(m_Value(UpperBRev))))
2261 return ConcatIntrinsicCalls(Intrinsic::bitreverse, UpperBRev, LowerBRev);
2262
2263 return nullptr;
2264}
2265
2266/// If all elements of two constant vectors are 0/-1 and inverses, return true.
2267static bool areInverseVectorBitmasks(Constant *C1, Constant *C2) {
2268 unsigned NumElts = cast<FixedVectorType>(C1->getType())->getNumElements();
2269 for (unsigned i = 0; i != NumElts; ++i) {
2270 Constant *EltC1 = C1->getAggregateElement(i);
2271 Constant *EltC2 = C2->getAggregateElement(i);
2272 if (!EltC1 || !EltC2)
2273 return false;
2274
2275 // One element must be all ones, and the other must be all zeros.
2276 if (!((match(EltC1, m_Zero()) && match(EltC2, m_AllOnes())) ||
2277 (match(EltC2, m_Zero()) && match(EltC1, m_AllOnes()))))
2278 return false;
2279 }
2280 return true;
2281}
2282
2283/// We have an expression of the form (A & C) | (B & D). If A is a scalar or
2284/// vector composed of all-zeros or all-ones values and is the bitwise 'not' of
2285/// B, it can be used as the condition operand of a select instruction.
2286Value *InstCombinerImpl::getSelectCondition(Value *A, Value *B) {
2287 // Step 1: We may have peeked through bitcasts in the caller.
2288 // Exit immediately if we don't have (vector) integer types.
2289 Type *Ty = A->getType();
2290 if (!Ty->isIntOrIntVectorTy() || !B->getType()->isIntOrIntVectorTy())
2291 return nullptr;
2292
2293 // Step 2: We need 0 or all-1's bitmasks.
2294 if (ComputeNumSignBits(A) != Ty->getScalarSizeInBits())
2295 return nullptr;
2296
2297 // Step 3: If B is the 'not' value of A, we have our answer.
2298 if (match(A, m_Not(m_Specific(B)))) {
2299 // If these are scalars or vectors of i1, A can be used directly.
2300 if (Ty->isIntOrIntVectorTy(1))
2301 return A;
2302 return Builder.CreateTrunc(A, CmpInst::makeCmpResultType(Ty));
2303 }
2304
2305 // If both operands are constants, see if the constants are inverse bitmasks.
2306 Constant *AConst, *BConst;
2307 if (match(A, m_Constant(AConst)) && match(B, m_Constant(BConst)))
2308 if (AConst == ConstantExpr::getNot(BConst))
2309 return Builder.CreateZExtOrTrunc(A, CmpInst::makeCmpResultType(Ty));
2310
2311 // Look for more complex patterns. The 'not' op may be hidden behind various
2312 // casts. Look through sexts and bitcasts to find the booleans.
2313 Value *Cond;
2314 Value *NotB;
2315 if (match(A, m_SExt(m_Value(Cond))) &&
2316 Cond->getType()->isIntOrIntVectorTy(1) &&
2317 match(B, m_OneUse(m_Not(m_Value(NotB))))) {
2318 NotB = peekThroughBitcast(NotB, true);
2319 if (match(NotB, m_SExt(m_Specific(Cond))))
2320 return Cond;
2321 }
2322
2323 // All scalar (and most vector) possibilities should be handled now.
2324 // Try more matches that only apply to non-splat constant vectors.
2325 if (!Ty->isVectorTy())
2326 return nullptr;
2327
2328 // If both operands are xor'd with constants using the same sexted boolean
2329 // operand, see if the constants are inverse bitmasks.
2330 // TODO: Use ConstantExpr::getNot()?
2331 if (match(A, (m_Xor(m_SExt(m_Value(Cond)), m_Constant(AConst)))) &&
2332 match(B, (m_Xor(m_SExt(m_Specific(Cond)), m_Constant(BConst)))) &&
2333 Cond->getType()->isIntOrIntVectorTy(1) &&
2334 areInverseVectorBitmasks(AConst, BConst)) {
2335 AConst = ConstantExpr::getTrunc(AConst, CmpInst::makeCmpResultType(Ty));
2336 return Builder.CreateXor(Cond, AConst);
2337 }
2338 return nullptr;
2339}
2340
2341/// We have an expression of the form (A & C) | (B & D). Try to simplify this
2342/// to "A' ? C : D", where A' is a boolean or vector of booleans.
2343Value *InstCombinerImpl::matchSelectFromAndOr(Value *A, Value *C, Value *B,
2344 Value *D) {
2345 // The potential condition of the select may be bitcasted. In that case, look
2346 // through its bitcast and the corresponding bitcast of the 'not' condition.
2347 Type *OrigType = A->getType();
2348 A = peekThroughBitcast(A, true);
2349 B = peekThroughBitcast(B, true);
2350 if (Value *Cond = getSelectCondition(A, B)) {
2351 // ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D))
2352 // The bitcasts will either all exist or all not exist. The builder will
2353 // not create unnecessary casts if the types already match.
2354 Value *BitcastC = Builder.CreateBitCast(C, A->getType());
2355 Value *BitcastD = Builder.CreateBitCast(D, A->getType());
2356 Value *Select = Builder.CreateSelect(Cond, BitcastC, BitcastD);
2357 return Builder.CreateBitCast(Select, OrigType);
2358 }
2359
2360 return nullptr;
2361}
2362
2363/// Fold (icmp)|(icmp) if possible.
2364Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
2365 BinaryOperator &Or) {
2366 const SimplifyQuery Q = SQ.getWithInstruction(&Or);
2367
2368 // Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
2369 // if K1 and K2 are a one-bit mask.
2370 if (Value *V = foldAndOrOfICmpsOfAndWithPow2(LHS, RHS, &Or,
2371 /* IsAnd */ false))
2372 return V;
2373
2374 ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
2375 Value *LHS0 = LHS->getOperand(0), *RHS0 = RHS->getOperand(0);
2376 Value *LHS1 = LHS->getOperand(1), *RHS1 = RHS->getOperand(1);
2377 auto *LHSC = dyn_cast<ConstantInt>(LHS1);
2378 auto *RHSC = dyn_cast<ConstantInt>(RHS1);
2379
2380 // Fold (icmp ult/ule (A + C1), C3) | (icmp ult/ule (A + C2), C3)
2381 // --> (icmp ult/ule ((A & ~(C1 ^ C2)) + max(C1, C2)), C3)
2382 // The original condition actually refers to the following two ranges:
2383 // [MAX_UINT-C1+1, MAX_UINT-C1+1+C3] and [MAX_UINT-C2+1, MAX_UINT-C2+1+C3]
2384 // We can fold these two ranges if:
2385 // 1) C1 and C2 is unsigned greater than C3.
2386 // 2) The two ranges are separated.
2387 // 3) C1 ^ C2 is one-bit mask.
2388 // 4) LowRange1 ^ LowRange2 and HighRange1 ^ HighRange2 are one-bit mask.
2389 // This implies all values in the two ranges differ by exactly one bit.
2390 if ((PredL == ICmpInst::ICMP_ULT || PredL == ICmpInst::ICMP_ULE) &&
2391 PredL == PredR && LHSC && RHSC && LHS->hasOneUse() && RHS->hasOneUse() &&
2392 LHSC->getType() == RHSC->getType() &&
2393 LHSC->getValue() == (RHSC->getValue())) {
2394
2395 Value *AddOpnd;
2396 ConstantInt *LAddC, *RAddC;
2397 if (match(LHS0, m_Add(m_Value(AddOpnd), m_ConstantInt(LAddC))) &&
2398 match(RHS0, m_Add(m_Specific(AddOpnd), m_ConstantInt(RAddC))) &&
2399 LAddC->getValue().ugt(LHSC->getValue()) &&
2400 RAddC->getValue().ugt(LHSC->getValue())) {
2401
2402 APInt DiffC = LAddC->getValue() ^ RAddC->getValue();
2403 if (DiffC.isPowerOf2()) {
2404 ConstantInt *MaxAddC = nullptr;
2405 if (LAddC->getValue().ult(RAddC->getValue()))
2406 MaxAddC = RAddC;
2407 else
2408 MaxAddC = LAddC;
2409
2410 APInt RRangeLow = -RAddC->getValue();
2411 APInt RRangeHigh = RRangeLow + LHSC->getValue();
2412 APInt LRangeLow = -LAddC->getValue();
2413 APInt LRangeHigh = LRangeLow + LHSC->getValue();
2414 APInt LowRangeDiff = RRangeLow ^ LRangeLow;
2415 APInt HighRangeDiff = RRangeHigh ^ LRangeHigh;
2416 APInt RangeDiff = LRangeLow.sgt(RRangeLow) ? LRangeLow - RRangeLow
2417 : RRangeLow - LRangeLow;
2418
2419 if (LowRangeDiff.isPowerOf2() && LowRangeDiff == HighRangeDiff &&
2420 RangeDiff.ugt(LHSC->getValue())) {
2421 Value *MaskC = ConstantInt::get(LAddC->getType(), ~DiffC);
2422
2423 Value *NewAnd = Builder.CreateAnd(AddOpnd, MaskC);
2424 Value *NewAdd = Builder.CreateAdd(NewAnd, MaxAddC);
2425 return Builder.CreateICmp(LHS->getPredicate(), NewAdd, LHSC);
2426 }
2427 }
2428 }
2429 }
2430
2431 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
2432 if (predicatesFoldable(PredL, PredR)) {
2433 if (LHS0 == RHS1 && LHS1 == RHS0)
2434 LHS->swapOperands();
2435 if (LHS0 == RHS0 && LHS1 == RHS1) {
2436 unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
2437 bool IsSigned = LHS->isSigned() || RHS->isSigned();
2438 return getNewICmpValue(Code, IsSigned, LHS0, LHS1, Builder);
2439 }
2440 }
2441
2442 // handle (roughly):
2443 // (icmp ne (A & B), C) | (icmp ne (A & D), E)
2444 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder))
2445 return V;
2446
2447 if (LHS->hasOneUse() || RHS->hasOneUse()) {
2448 // (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1)
2449 // (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1)
2450 Value *A = nullptr, *B = nullptr;
2451 if (PredL == ICmpInst::ICMP_EQ && match(LHS1, m_Zero())) {
2452 B = LHS0;
2453 if (PredR == ICmpInst::ICMP_ULT && LHS0 == RHS1)
2454 A = RHS0;
2455 else if (PredR == ICmpInst::ICMP_UGT && LHS0 == RHS0)
2456 A = RHS1;
2457 }
2458 // (icmp ult A, B) | (icmp eq B, 0) -> (icmp ule A, B-1)
2459 // (icmp ugt B, A) | (icmp eq B, 0) -> (icmp ule A, B-1)
2460 else if (PredR == ICmpInst::ICMP_EQ && match(RHS1, m_Zero())) {
2461 B = RHS0;
2462 if (PredL == ICmpInst::ICMP_ULT && RHS0 == LHS1)
2463 A = LHS0;
2464 else if (PredL == ICmpInst::ICMP_UGT && RHS0 == LHS0)
2465 A = LHS1;
2466 }
2467 if (A && B && B->getType()->isIntOrIntVectorTy())
2468 return Builder.CreateICmp(
2469 ICmpInst::ICMP_UGE,
2470 Builder.CreateAdd(B, Constant::getAllOnesValue(B->getType())), A);
2471 }
2472
2473 if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, Or, Builder, Q))
2474 return V;
2475 if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, Or, Builder, Q))
2476 return V;
2477
2478 // E.g. (icmp slt x, 0) | (icmp sgt x, n) --> icmp ugt x, n
2479 if (Value *V = simplifyRangeCheck(LHS, RHS, /*Inverted=*/true))
2480 return V;
2481
2482 // E.g. (icmp sgt x, n) | (icmp slt x, 0) --> icmp ugt x, n
2483 if (Value *V = simplifyRangeCheck(RHS, LHS, /*Inverted=*/true))
2484 return V;
2485
2486 if (Value *V = foldAndOrOfEqualityCmpsWithConstants(LHS, RHS, false, Builder))
2487 return V;
2488
2489 if (Value *V = foldIsPowerOf2(LHS, RHS, false /* JoinedByAnd */, Builder))
2490 return V;
2491
2492 if (Value *X =
2493 foldUnsignedUnderflowCheck(LHS, RHS, /*IsAnd=*/false, Q, Builder))
2494 return X;
2495 if (Value *X =
2496 foldUnsignedUnderflowCheck(RHS, LHS, /*IsAnd=*/false, Q, Builder))
2497 return X;
2498
2499 if (Value *X = foldEqOfParts(LHS, RHS, /*IsAnd=*/false))
2500 return X;
2501
2502 // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
2503 // TODO: Remove this when foldLogOpOfMaskedICmps can handle vectors.
2504 if (PredL == ICmpInst::ICMP_NE && match(LHS1, m_Zero()) &&
2505 PredR == ICmpInst::ICMP_NE && match(RHS1, m_Zero()) &&
2506 LHS0->getType()->isIntOrIntVectorTy() &&
2507 LHS0->getType() == RHS0->getType()) {
2508 Value *NewOr = Builder.CreateOr(LHS0, RHS0);
2509 return Builder.CreateICmp(PredL, NewOr,
2510 Constant::getNullValue(NewOr->getType()));
2511 }
2512
2513 // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
2514 if (!LHSC || !RHSC)
2515 return nullptr;
2516
2517 // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1)
2518 // iff C2 + CA == C1.
2519 if (PredL == ICmpInst::ICMP_ULT && PredR == ICmpInst::ICMP_EQ) {
2520 ConstantInt *AddC;
2521 if (match(LHS0, m_Add(m_Specific(RHS0), m_ConstantInt(AddC))))
2522 if (RHSC->getValue() + AddC->getValue() == LHSC->getValue())
2523 return Builder.CreateICmpULE(LHS0, LHSC);
2524 }
2525
2526 // From here on, we only handle:
2527 // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
2528 if (LHS0 != RHS0)
2529 return nullptr;
2530
2531 // ICMP_[US][GL]E X, C is folded to ICMP_[US][GL]T elsewhere.
2532 if (PredL == ICmpInst::ICMP_UGE || PredL == ICmpInst::ICMP_ULE ||
2533 PredR == ICmpInst::ICMP_UGE || PredR == ICmpInst::ICMP_ULE ||
2534 PredL == ICmpInst::ICMP_SGE || PredL == ICmpInst::ICMP_SLE ||
2535 PredR == ICmpInst::ICMP_SGE || PredR == ICmpInst::ICMP_SLE)
2536 return nullptr;
2537
2538 // We can't fold (ugt x, C) | (sgt x, C2).
2539 if (!predicatesFoldable(PredL, PredR))
2540 return nullptr;
2541
2542 // Ensure that the larger constant is on the RHS.
2543 bool ShouldSwap;
2544 if (CmpInst::isSigned(PredL) ||
2545 (ICmpInst::isEquality(PredL) && CmpInst::isSigned(PredR)))
2546 ShouldSwap = LHSC->getValue().sgt(RHSC->getValue());
2547 else
2548 ShouldSwap = LHSC->getValue().ugt(RHSC->getValue());
2549
2550 if (ShouldSwap) {
2551 std::swap(LHS, RHS);
2552 std::swap(LHSC, RHSC);
2553 std::swap(PredL, PredR);
2554 }
2555
2556 // At this point, we know we have two icmp instructions
2557 // comparing a value against two constants and or'ing the result
2558 // together. Because of the above check, we know that we only have
2559 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
2560 // icmp folding check above), that the two constants are not
2561 // equal.
2562 assert(LHSC != RHSC && "Compares not folded above?")(static_cast<void> (0));
2563
2564 switch (PredL) {
2565 default:
2566 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
2567 case ICmpInst::ICMP_EQ:
2568 switch (PredR) {
2569 default:
2570 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
2571 case ICmpInst::ICMP_EQ:
2572 // Potential folds for this case should already be handled.
2573 break;
2574 case ICmpInst::ICMP_UGT:
2575 // (X == 0 || X u> C) -> (X-1) u>= C
2576 if (LHSC->isMinValue(false))
2577 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
2578 false, false);
2579 // (X == 13 | X u> 14) -> no change
2580 break;
2581 case ICmpInst::ICMP_SGT:
2582 // (X == INT_MIN || X s> C) -> (X-(INT_MIN+1)) u>= C-INT_MIN
2583 if (LHSC->isMinValue(true))
2584 return insertRangeTest(LHS0, LHSC->getValue() + 1, RHSC->getValue() + 1,
2585 true, false);
2586 // (X == 13 | X s> 14) -> no change
2587 break;
2588 }
2589 break;
2590 case ICmpInst::ICMP_ULT:
2591 switch (PredR) {
2592 default:
2593 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
2594 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
2595 // (X u< C || X == UINT_MAX) => (X-C) u>= UINT_MAX-C
2596 if (RHSC->isMaxValue(false))
2597 return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
2598 false, false);
2599 break;
2600 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
2601 assert(!RHSC->isMaxValue(false) && "Missed icmp simplification")(static_cast<void> (0));
2602 return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1,
2603 false, false);
2604 }
2605 break;
2606 case ICmpInst::ICMP_SLT:
2607 switch (PredR) {
2608 default:
2609 llvm_unreachable("Unknown integer condition code!")__builtin_unreachable();
2610 case ICmpInst::ICMP_EQ:
2611 // (X s< C || X == INT_MAX) => (X-C) u>= INT_MAX-C
2612 if (RHSC->isMaxValue(true))
2613 return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue(),
2614 true, false);
2615 // (X s< 13 | X == 14) -> no change
2616 break;
2617 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) u> 2
2618 assert(!RHSC->isMaxValue(true) && "Missed icmp simplification")(static_cast<void> (0));
2619 return insertRangeTest(LHS0, LHSC->getValue(), RHSC->getValue() + 1, true,
2620 false);
2621 }
2622 break;
2623 }
2624 return nullptr;
2625}
2626
2627// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
2628// here. We should standardize that construct where it is needed or choose some
2629// other way to ensure that commutated variants of patterns are not missed.
2630Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
2631 if (Value *V = SimplifyOrInst(I.getOperand(0), I.getOperand(1),
2632 SQ.getWithInstruction(&I)))
2633 return replaceInstUsesWith(I, V);
2634
2635 if (SimplifyAssociativeOrCommutative(I))
2636 return &I;
2637
2638 if (Instruction *X = foldVectorBinop(I))
2639 return X;
2640
2641 // See if we can simplify any instructions used by the instruction whose sole
2642 // purpose is to compute bits we don't care about.
2643 if (SimplifyDemandedInstructionBits(I))
2644 return &I;
2645
2646 // Do this before using distributive laws to catch simple and/or/not patterns.
2647 if (Instruction *Xor = foldOrToXor(I, Builder))
2648 return Xor;
2649
2650 // (A&B)|(A&C) -> A&(B|C) etc
2651 if (Value *V = SimplifyUsingDistributiveLaws(I))
2652 return replaceInstUsesWith(I, V);
2653
2654 if (Value *V = SimplifyBSwap(I, Builder))
2655 return replaceInstUsesWith(I, V);
2656
2657 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2658 if (I.getType()->isIntOrIntVectorTy(1)) {
2659 if (auto *SI0 = dyn_cast<SelectInst>(Op0)) {
2660 if (auto *I =
2661 foldAndOrOfSelectUsingImpliedCond(Op1, *SI0, /* IsAnd */ false))
2662 return I;
2663 }
2664 if (auto *SI1 = dyn_cast<SelectInst>(Op1)) {
2665 if (auto *I =
2666 foldAndOrOfSelectUsingImpliedCond(Op0, *SI1, /* IsAnd */ false))
2667 return I;
2668 }
2669 }
2670
2671 if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
2672 return FoldedLogic;
2673
2674 if (Instruction *BitOp = matchBSwapOrBitReverse(I, /*MatchBSwaps*/ true,
2675 /*MatchBitReversals*/ true))
2676 return BitOp;
2677
2678 if (Instruction *Funnel = matchFunnelShift(I, *this))
2679 return Funnel;
2680
2681 if (Instruction *Concat = matchOrConcat(I, Builder))
2682 return replaceInstUsesWith(I, Concat);
2683
2684 Value *X, *Y;
2685 const APInt *CV;
2686 if (match(&I, m_c_Or(m_OneUse(m_Xor(m_Value(X), m_APInt(CV))), m_Value(Y))) &&
2687 !CV->isAllOnesValue() && MaskedValueIsZero(Y, *CV, 0, &I)) {
2688 // (X ^ C) | Y -> (X | Y) ^ C iff Y & C == 0
2689 // The check for a 'not' op is for efficiency (if Y is known zero --> ~X).
2690 Value *Or = Builder.CreateOr(X, Y);
2691 return BinaryOperator::CreateXor(Or, ConstantInt::get(I.getType(), *CV));
2692 }
2693
2694 // (A & C)|(B & D)
2695 Value *A, *B, *C, *D;
2696 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
2697 match(Op1, m_And(m_Value(B), m_Value(D)))) {
2698 // (A & C1)|(B & C2)
2699 ConstantInt *C1, *C2;
2700 if (match(C, m_ConstantInt(C1)) && match(D, m_ConstantInt(C2))) {
2701 Value *V1 = nullptr, *V2 = nullptr;
2702 if ((C1->getValue() & C2->getValue()).isNullValue()) {
2703 // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
2704 // iff (C1&C2) == 0 and (N&~C1) == 0
2705 if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
2706 ((V1 == B &&
2707 MaskedValueIsZero(V2, ~C1->getValue(), 0, &I)) || // (V|N)
2708 (V2 == B &&
2709 MaskedValueIsZero(V1, ~C1->getValue(), 0, &I)))) // (N|V)
2710 return BinaryOperator::CreateAnd(A,
2711 Builder.getInt(C1->getValue()|C2->getValue()));
2712 // Or commutes, try both ways.
2713 if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
2714 ((V1 == A &&
2715 MaskedValueIsZero(V2, ~C2->getValue(), 0, &I)) || // (V|N)
2716 (V2 == A &&
2717 MaskedValueIsZero(V1, ~C2->getValue(), 0, &I)))) // (N|V)
2718 return BinaryOperator::CreateAnd(B,
2719 Builder.getInt(C1->getValue()|C2->getValue()));
2720
2721 // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2)
2722 // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0.
2723 ConstantInt *C3 = nullptr, *C4 = nullptr;
2724 if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) &&
2725 (C3->getValue() & ~C1->getValue()).isNullValue() &&
2726 match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) &&
2727 (C4->getValue() & ~C2->getValue()).isNullValue()) {
2728 V2 = Builder.CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield");
2729 return BinaryOperator::CreateAnd(V2,
2730 Builder.getInt(C1->getValue()|C2->getValue()));
2731 }
2732 }
2733
2734 if (C1->getValue() == ~C2->getValue()) {
2735 Value *X;
2736
2737 // ((X|B)&C1)|(B&C2) -> (X&C1) | B iff C1 == ~C2
2738 if (match(A, m_c_Or(m_Value(X), m_Specific(B))))
2739 return BinaryOperator::CreateOr(Builder.CreateAnd(X, C1), B);
2740 // (A&C2)|((X|A)&C1) -> (X&C2) | A iff C1 == ~C2
2741 if (match(B, m_c_Or(m_Specific(A), m_Value(X))))
2742 return BinaryOperator::CreateOr(Builder.CreateAnd(X, C2), A);
2743
2744 // ((X^B)&C1)|(B&C2) -> (X&C1) ^ B iff C1 == ~C2
2745 if (match(A, m_c_Xor(m_Value(X), m_Specific(B))))
2746 return BinaryOperator::CreateXor(Builder.CreateAnd(X, C1), B);
2747 // (A&C2)|((X^A)&C1) -> (X&C2) ^ A iff C1 == ~C2
2748 if (match(B, m_c_Xor(m_Specific(A), m_Value(X))))
2749 return BinaryOperator::CreateXor(Builder.CreateAnd(X, C2), A);
2750 }
2751 }
2752
2753 // Don't try to form a select if it's unlikely that we'll get rid of at
2754 // least one of the operands. A select is generally more expensive than the
2755 // 'or' that it is replacing.
2756 if (Op0->hasOneUse() || Op1->hasOneUse()) {
2757 // (Cond & C) | (~Cond & D) -> Cond ? C : D, and commuted variants.
2758 if (Value *V = matchSelectFromAndOr(A, C, B, D))
2759 return replaceInstUsesWith(I, V);
2760 if (Value *V = matchSelectFromAndOr(A, C, D, B))
2761 return replaceInstUsesWith(I, V);
2762 if (Value *V = matchSelectFromAndOr(C, A, B, D))
2763 return replaceInstUsesWith(I, V);
2764 if (Value *V = matchSelectFromAndOr(C, A, D, B))
2765 return replaceInstUsesWith(I, V);
2766 if (Value *V = matchSelectFromAndOr(B, D, A, C))
2767 return replaceInstUsesWith(I, V);
2768 if (Value *V = matchSelectFromAndOr(B, D, C, A))
2769 return replaceInstUsesWith(I, V);
2770 if (Value *V = matchSelectFromAndOr(D, B, A, C))
2771 return replaceInstUsesWith(I, V);
2772 if (Value *V = matchSelectFromAndOr(D, B, C, A))
2773 return replaceInstUsesWith(I, V);
2774 }
2775 }
2776
2777 // (A ^ B) | ((B ^ C) ^ A) -> (A ^ B) | C
2778 if (match(Op0, m_Xor(m_Value(A), m_Value(B))))
2779 if (match(Op1, m_Xor(m_Xor(m_Specific(B), m_Value(C)), m_Specific(A))))
2780 return BinaryOperator::CreateOr(Op0, C);
2781
2782 // ((A ^ C) ^ B) | (B ^ A) -> (B ^ A) | C
2783 if (match(Op0, m_Xor(m_Xor(m_Value(A), m_Value(C)), m_Value(B))))
2784 if (match(Op1, m_Xor(m_Specific(B), m_Specific(A))))
2785 return BinaryOperator::CreateOr(Op1, C);
2786
2787 // ((B | C) & A) | B -> B | (A & C)
2788 if (match(Op0, m_And(m_Or(m_Specific(Op1), m_Value(C)), m_Value(A))))
2789 return BinaryOperator::CreateOr(Op1, Builder.CreateAnd(A, C));
2790
2791 if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
2792 return DeMorgan;
2793
2794 // Canonicalize xor to the RHS.
2795 bool SwappedForXor = false;
2796 if (match(Op0, m_Xor(m_Value(), m_Value()))) {
2797 std::swap(Op0, Op1);
2798 SwappedForXor = true;
2799 }
2800
2801 // A | ( A ^ B) -> A | B
2802 // A | (~A ^ B) -> A | ~B
2803 // (A & B) | (A ^ B)
2804 if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
2805 if (Op0 == A || Op0 == B)
2806 return BinaryOperator::CreateOr(A, B);
2807
2808 if (match(Op0, m_And(m_Specific(A), m_Specific(B))) ||
2809 match(Op0, m_And(m_Specific(B), m_Specific(A))))
2810 return BinaryOperator::CreateOr(A, B);
2811
2812 if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) {
2813 Value *Not = Builder.CreateNot(B, B->getName() + ".not");
2814 return BinaryOperator::CreateOr(Not, Op0);
2815 }
2816 if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) {
2817 Value *Not = Builder.CreateNot(A, A->getName() + ".not");
2818 return BinaryOperator::CreateOr(Not, Op0);
2819 }
2820 }
2821
2822 // A | ~(A | B) -> A | ~B
2823 // A | ~(A ^ B) -> A | ~B
2824 if (match(Op1, m_Not(m_Value(A))))
2825 if (BinaryOperator *B = dyn_cast<BinaryOperator>(A))
2826 if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) &&
2827 Op1->hasOneUse() && (B->getOpcode() == Instruction::Or ||
2828 B->getOpcode() == Instruction::Xor)) {
2829 Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) :
2830 B->getOperand(0);
2831 Value *Not = Builder.CreateNot(NotOp, NotOp->getName() + ".not");
2832 return BinaryOperator::CreateOr(Not, Op0);
2833 }
2834
2835 if (SwappedForXor)
2836 std::swap(Op0, Op1);
2837
2838 {
2839 ICmpInst *LHS = dyn_cast<ICmpInst>(Op0);
2840 ICmpInst *RHS = dyn_cast<ICmpInst>(Op1);
2841 if (LHS && RHS)
2842 if (Value *Res = foldOrOfICmps(LHS, RHS, I))
2843 return replaceInstUsesWith(I, Res);
2844
2845 // TODO: Make this recursive; it's a little tricky because an arbitrary
2846 // number of 'or' instructions might have to be created.
2847 Value *X, *Y;
2848 if (LHS && match(Op1, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
2849 if (auto *Cmp = dyn_cast<ICmpInst>(X))
2850 if (Value *Res = foldOrOfICmps(LHS, Cmp, I))
2851 return replaceInstUsesWith(I, Builder.CreateOr(Res, Y));
2852 if (auto *Cmp = dyn_cast<ICmpInst>(Y))
2853 if (Value *Res = foldOrOfICmps(LHS, Cmp, I))
2854 return replaceInstUsesWith(I, Builder.CreateOr(Res, X));
2855 }
2856 if (RHS && match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {
2857 if (auto *Cmp = dyn_cast<ICmpInst>(X))
2858 if (Value *Res = foldOrOfICmps(Cmp, RHS, I))
2859 return replaceInstUsesWith(I, Builder.CreateOr(Res, Y));
2860 if (auto *Cmp = dyn_cast<ICmpInst>(Y))
2861 if (Value *Res = foldOrOfICmps(Cmp, RHS, I))
2862 return replaceInstUsesWith(I, Builder.CreateOr(Res, X));
2863 }
2864 }
2865
2866 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
2867 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
2868 if (Value *Res = foldLogicOfFCmps(LHS, RHS, false))
2869 return replaceInstUsesWith(I, Res);
2870
2871 if (Instruction *FoldedFCmps = reassociateFCmps(I, Builder))
2872 return FoldedFCmps;
2873
2874 if (Instruction *CastedOr = foldCastedBitwiseLogic(I))
2875 return CastedOr;
2876
2877 // or(sext(A), B) / or(B, sext(A)) --> A ? -1 : B, where A is i1 or <N x i1>.
2878 if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
2879 A->getType()->isIntOrIntVectorTy(1))
2880 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
2881 if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
2882 A->getType()->isIntOrIntVectorTy(1))
2883 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
2884
2885 // Note: If we've gotten to the point of visiting the outer OR, then the
2886 // inner one couldn't be simplified. If it was a constant, then it won't
2887 // be simplified by a later pass either, so we try swapping the inner/outer
2888 // ORs in the hopes that we'll be able to simplify it this way.
2889 // (X|C) | V --> (X|V) | C
2890 ConstantInt *CI;
2891 if (Op0->hasOneUse() && !match(Op1, m_ConstantInt()) &&
2892 match(Op0, m_Or(m_Value(A), m_ConstantInt(CI)))) {
2893 Value *Inner = Builder.CreateOr(A, Op1);
2894 Inner->takeName(Op0);
2895 return BinaryOperator::CreateOr(Inner, CI);
2896 }
2897
2898 // Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
2899 // Since this OR statement hasn't been optimized further yet, we hope
2900 // that this transformation will allow the new ORs to be optimized.
2901 {
2902 Value *X = nullptr, *Y = nullptr;
2903 if (Op0->hasOneUse() && Op1->hasOneUse() &&
2904 match(Op0, m_Select(m_Value(X), m_Value(A), m_Value(B))) &&
2905 match(Op1, m_Select(m_Value(Y), m_Value(C), m_Value(D))) && X == Y) {
2906 Value *orTrue = Builder.CreateOr(A, C);
2907 Value *orFalse = Builder.CreateOr(B, D);
2908 return SelectInst::Create(X, orTrue, orFalse);
2909 }
2910 }
2911
2912 // or(ashr(subNSW(Y, X), ScalarSizeInBits(Y) - 1), X) --> X s> Y ? -1 : X.
2913 {
2914 Value *X, *Y;
2915 Type *Ty = I.getType();
2916 if (match(&I, m_c_Or(m_OneUse(m_AShr(
2917 m_NSWSub(m_Value(Y), m_Value(X)),
2918 m_SpecificInt(Ty->getScalarSizeInBits() - 1))),
2919 m_Deferred(X)))) {
2920 Value *NewICmpInst = Builder.CreateICmpSGT(X, Y);
2921 Value *AllOnes = ConstantInt::getAllOnesValue(Ty);
2922 return SelectInst::Create(NewICmpInst, AllOnes, X);
2923 }
2924 }
2925
2926 if (Instruction *V =
2927 canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I))
2928 return V;
2929
2930 CmpInst::Predicate Pred;
2931 Value *Mul, *Ov, *MulIsNotZero, *UMulWithOv;
2932 // Check if the OR weakens the overflow condition for umul.with.overflow by
2933 // treating any non-zero result as overflow. In that case, we overflow if both
2934 // umul.with.overflow operands are != 0, as in that case the result can only
2935 // be 0, iff the multiplication overflows.
2936 if (match(&I,
2937 m_c_Or(m_CombineAnd(m_ExtractValue<1>(m_Value(UMulWithOv)),
2938 m_Value(Ov)),
2939 m_CombineAnd(m_ICmp(Pred,
2940 m_CombineAnd(m_ExtractValue<0>(
2941 m_Deferred(UMulWithOv)),
2942 m_Value(Mul)),
2943 m_ZeroInt()),
2944 m_Value(MulIsNotZero)))) &&
2945 (Ov->hasOneUse() || (MulIsNotZero->hasOneUse() && Mul->hasOneUse())) &&
2946 Pred == CmpInst::ICMP_NE) {
2947 Value *A, *B;
2948 if (match(UMulWithOv, m_Intrinsic<Intrinsic::umul_with_overflow>(
2949 m_Value(A), m_Value(B)))) {
2950 Value *NotNullA = Builder.CreateIsNotNull(A);
2951 Value *NotNullB = Builder.CreateIsNotNull(B);
2952 return BinaryOperator::CreateAnd(NotNullA, NotNullB);
2953 }
2954 }
2955
2956 // (~x) | y --> ~(x & (~y)) iff that gets rid of inversions
2957 if (sinkNotIntoOtherHandOfAndOrOr(I))
2958 return &I;
2959
2960 // Improve "get low bit mask up to and including bit X" pattern:
2961 // (1 << X) | ((1 << X) + -1) --> -1 l>> (bitwidth(x) - 1 - X)
2962 if (match(&I, m_c_Or(m_Add(m_Shl(m_One(), m_Value(X)), m_AllOnes()),
2963 m_Shl(m_One(), m_Deferred(X)))) &&
2964 match(&I, m_c_Or(m_OneUse(m_Value()), m_Value()))) {
2965 Type *Ty = X->getType();
2966 Value *Sub = Builder.CreateSub(
2967 ConstantInt::get(Ty, Ty->getScalarSizeInBits() - 1), X);
2968 return BinaryOperator::CreateLShr(Constant::getAllOnesValue(Ty), Sub);
2969 }
2970
2971 // An or recurrence w/loop invariant step is equivelent to (or start, step)
2972 PHINode *PN = nullptr;
2973 Value *Start = nullptr, *Step = nullptr;
2974 if (matchSimpleRecurrence(&I, PN, Start, Step) && DT.dominates(Step, PN))
2975 return replaceInstUsesWith(I, Builder.CreateOr(Start, Step));
2976
2977 return nullptr;
2978}
2979
2980/// A ^ B can be specified using other logic ops in a variety of patterns. We
2981/// can fold these early and efficiently by morphing an existing instruction.
2982static Instruction *foldXorToXor(BinaryOperator &I,
2983 InstCombiner::BuilderTy &Builder) {
2984 assert(I.getOpcode() == Instruction::Xor)(static_cast<void> (0));
2985 Value *Op0 = I.getOperand(0);
2986 Value *Op1 = I.getOperand(1);
2987 Value *A, *B;
2988
2989 // There are 4 commuted variants for each of the basic patterns.
2990
2991 // (A & B) ^ (A | B) -> A ^ B
2992 // (A & B) ^ (B | A) -> A ^ B
2993 // (A | B) ^ (A & B) -> A ^ B
2994 // (A | B) ^ (B & A) -> A ^ B
2995 if (match(&I, m_c_Xor(m_And(m_Value(A), m_Value(B)),
2996 m_c_Or(m_Deferred(A), m_Deferred(B)))))
2997 return BinaryOperator::CreateXor(A, B);
2998
2999 // (A | ~B) ^ (~A | B) -> A ^ B
3000 // (~B | A) ^ (~A | B) -> A ^ B
3001 // (~A | B) ^ (A | ~B) -> A ^ B
3002 // (B | ~A) ^ (A | ~B) -> A ^ B
3003 if (match(&I, m_Xor(m_c_Or(m_Value(A), m_Not(m_Value(B))),
3004 m_c_Or(m_Not(m_Deferred(A)), m_Deferred(B)))))
3005 return BinaryOperator::CreateXor(A, B);
3006
3007 // (A & ~B) ^ (~A & B) -> A ^ B
3008 // (~B & A) ^ (~A & B) -> A ^ B
3009 // (~A & B) ^ (A & ~B) -> A ^ B
3010 // (B & ~A) ^ (A & ~B) -> A ^ B
3011 if (match(&I, m_Xor(m_c_And(m_Value(A), m_Not(m_Value(B))),
3012 m_c_And(m_Not(m_Deferred(A)), m_Deferred(B)))))
3013 return BinaryOperator::CreateXor(A, B);
3014
3015 // For the remaining cases we need to get rid of one of the operands.
3016 if (!Op0->hasOneUse() && !Op1->hasOneUse())
3017 return nullptr;
3018
3019 // (A | B) ^ ~(A & B) -> ~(A ^ B)
3020 // (A | B) ^ ~(B & A) -> ~(A ^ B)
3021 // (A & B) ^ ~(A | B) -> ~(A ^ B)
3022 // (A & B) ^ ~(B | A) -> ~(A ^ B)
3023 // Complexity sorting ensures the not will be on the right side.
3024 if ((match(Op0, m_Or(m_Value(A), m_Value(B))) &&
3025 match(Op1, m_Not(m_c_And(m_Specific(A), m_Specific(B))))) ||
3026 (match(Op0, m_And(m_Value(A), m_Value(B))) &&
3027 match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B))))))
3028 return BinaryOperator::CreateNot(Builder.CreateXor(A, B));
3029
3030 return nullptr;
3031}
3032
3033Value *InstCombinerImpl::foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS,
3034 BinaryOperator &I) {
3035 assert(I.getOpcode() == Instruction::Xor && I.getOperand(0) == LHS &&(static_cast<void> (0))
3036 I.getOperand(1) == RHS && "Should be 'xor' with these operands")(static_cast<void> (0));
3037
3038 if (predicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) {
3039 if (LHS->getOperand(0) == RHS->getOperand(1) &&
3040 LHS->getOperand(1) == RHS->getOperand(0))
3041 LHS->swapOperands();
3042 if (LHS->getOperand(0) == RHS->getOperand(0) &&
3043 LHS->getOperand(1) == RHS->getOperand(1)) {
3044 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
3045 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
3046 unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
3047 bool IsSigned = LHS->isSigned() || RHS->isSigned();
3048 return getNewICmpValue(Code, IsSigned, Op0, Op1, Builder);
3049 }
3050 }
3051
3052 // TODO: This can be generalized to compares of non-signbits using
3053 // decomposeBitTestICmp(). It could be enhanced more by using (something like)
3054 // foldLogOpOfMaskedICmps().
3055 ICmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
3056 Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
3057 Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
3058 if ((LHS->hasOneUse() || RHS->hasOneUse()) &&
3059 LHS0->getType() == RHS0->getType() &&
3060 LHS0->getType()->isIntOrIntVectorTy()) {
3061 // (X > -1) ^ (Y > -1) --> (X ^ Y) < 0
3062 // (X < 0) ^ (Y < 0) --> (X ^ Y) < 0
3063 if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
3064 PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes())) ||
3065 (PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
3066 PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero()))) {
3067 Value *Zero = ConstantInt::getNullValue(LHS0->getType());
3068 return Builder.CreateICmpSLT(Builder.CreateXor(LHS0, RHS0), Zero);
3069 }
3070 // (X > -1) ^ (Y < 0) --> (X ^ Y) > -1
3071 // (X < 0) ^ (Y > -1) --> (X ^ Y) > -1
3072 if ((PredL == CmpInst::ICMP_SGT && match(LHS1, m_AllOnes()) &&
3073 PredR == CmpInst::ICMP_SLT && match(RHS1, m_Zero())) ||
3074 (PredL == CmpInst::ICMP_SLT && match(LHS1, m_Zero()) &&
3075 PredR == CmpInst::ICMP_SGT && match(RHS1, m_AllOnes()))) {
3076 Value *MinusOne = ConstantInt::getAllOnesValue(LHS0->getType());
3077 return Builder.CreateICmpSGT(Builder.CreateXor(LHS0, RHS0), MinusOne);
3078 }
3079 }
3080
3081 // Instead of trying to imitate the folds for and/or, decompose this 'xor'
3082 // into those logic ops. That is, try to turn this into an and-of-icmps
3083 // because we have many folds for that pattern.
3084 //
3085 // This is based on a truth table definition of xor:
3086 // X ^ Y --> (X | Y) & !(X & Y)
3087 if (Value *OrICmp = SimplifyBinOp(Instruction::Or, LHS, RHS, SQ)) {
3088 // TODO: If OrICmp is true, then the definition of xor simplifies to !(X&Y).
3089 // TODO: If OrICmp is false, the whole thing is false (InstSimplify?).
3090 if (Value *AndICmp = SimplifyBinOp(Instruction::And, LHS, RHS, SQ)) {
3091 // TODO: Independently handle cases where the 'and' side is a constant.
3092 ICmpInst *X = nullptr, *Y = nullptr;
3093 if (OrICmp == LHS && AndICmp == RHS) {
3094 // (LHS | RHS) & !(LHS & RHS) --> LHS & !RHS --> X & !Y
3095 X = LHS;
3096 Y = RHS;
3097 }
3098 if (OrICmp == RHS && AndICmp == LHS) {
3099 // !(LHS & RHS) & (LHS | RHS) --> !LHS & RHS --> !Y & X
3100 X = RHS;
3101 Y = LHS;
3102 }
3103 if (X && Y && (Y->hasOneUse() || canFreelyInvertAllUsersOf(Y, &I))) {
3104 // Invert the predicate of 'Y', thus inverting its output.
3105 Y->setPredicate(Y->getInversePredicate());
3106 // So, are there other uses of Y?
3107 if (!Y->hasOneUse()) {
3108 // We need to adapt other uses of Y though. Get a value that matches
3109 // the original value of Y before inversion. While this increases
3110 // immediate instruction count, we have just ensured that all the
3111 // users are freely-invertible, so that 'not' *will* get folded away.
3112 BuilderTy::InsertPointGuard Guard(Builder);
3113 // Set insertion point to right after the Y.
3114 Builder.SetInsertPoint(Y->getParent(), ++(Y->getIterator()));
3115 Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
3116 // Replace all uses of Y (excluding the one in NotY!) with NotY.
3117 Worklist.pushUsersToWorkList(*Y);
3118 Y->replaceUsesWithIf(NotY,
3119 [NotY](Use &U) { return U.getUser() != NotY; });
3120 }
3121 // All done.
3122 return Builder.CreateAnd(LHS, RHS);
3123 }
3124 }
3125 }
3126
3127 return nullptr;
3128}
3129
3130/// If we have a masked merge, in the canonical form of:
3131/// (assuming that A only has one use.)
3132/// | A | |B|
3133/// ((x ^ y) & M) ^ y
3134/// | D |
3135/// * If M is inverted:
3136/// | D |
3137/// ((x ^ y) & ~M) ^ y
3138/// We can canonicalize by swapping the final xor operand
3139/// to eliminate the 'not' of the mask.
3140/// ((x ^ y) & M) ^ x
3141/// * If M is a constant, and D has one use, we transform to 'and' / 'or' ops
3142/// because that shortens the dependency chain and improves analysis:
3143/// (x & M) | (y & ~M)
3144static Instruction *visitMaskedMerge(BinaryOperator &I,
3145 InstCombiner::BuilderTy &Builder) {
3146 Value *B, *X, *D;
3147 Value *M;
3148 if (!match(&I, m_c_Xor(m_Value(B),
3149 m_OneUse(m_c_And(
3150 m_CombineAnd(m_c_Xor(m_Deferred(B), m_Value(X)),
3151 m_Value(D)),
3152 m_Value(M))))))
3153 return nullptr;
3154
3155 Value *NotM;
3156 if (match(M, m_Not(m_Value(NotM)))) {
3157 // De-invert the mask and swap the value in B part.
3158 Value *NewA = Builder.CreateAnd(D, NotM);
3159 return BinaryOperator::CreateXor(NewA, X);
3160 }
3161
3162 Constant *C;
3163 if (D->hasOneUse() && match(M, m_Constant(C))) {
3164 // Propagating undef is unsafe. Clamp undef elements to -1.
3165 Type *EltTy = C->getType()->getScalarType();
3166 C = Constant::replaceUndefsWith(C, ConstantInt::getAllOnesValue(EltTy));
3167 // Unfold.
3168 Value *LHS = Builder.CreateAnd(X, C);
3169 Value *NotC = Builder.CreateNot(C);
3170 Value *RHS = Builder.CreateAnd(B, NotC);
3171 return BinaryOperator::CreateOr(LHS, RHS);
3172 }
3173
3174 return nullptr;
3175}
3176
3177// Transform
3178// ~(x ^ y)
3179// into:
3180// (~x) ^ y
3181// or into
3182// x ^ (~y)
3183static Instruction *sinkNotIntoXor(BinaryOperator &I,
3184 InstCombiner::BuilderTy &Builder) {
3185 Value *X, *Y;
3186 // FIXME: one-use check is not needed in general, but currently we are unable
3187 // to fold 'not' into 'icmp', if that 'icmp' has multiple uses. (D35182)
3188 if (!match(&I, m_Not(m_OneUse(m_Xor(m_Value(X), m_Value(Y))))))
3189 return nullptr;
3190
3191 // We only want to do the transform if it is free to do.
3192 if (InstCombiner::isFreeToInvert(X, X->hasOneUse())) {
3193 // Ok, good.
3194 } else if (InstCombiner::isFreeToInvert(Y, Y->hasOneUse())) {
3195 std::swap(X, Y);
3196 } else
3197 return nullptr;
3198
3199 Value *NotX = Builder.CreateNot(X, X->getName() + ".not");
3200 return BinaryOperator::CreateXor(NotX, Y, I.getName() + ".demorgan");
3201}
3202
3203/// Canonicalize a shifty way to code absolute value to the more common pattern
3204/// that uses negation and select.
3205static Instruction *canonicalizeAbs(BinaryOperator &Xor,
3206 InstCombiner::BuilderTy &Builder) {
3207 assert(Xor.getOpcode() == Instruction::Xor && "Expected an xor instruction.")(static_cast<void> (0));
3208
3209 // There are 4 potential commuted variants. Move the 'ashr' candidate to Op1.
3210 // We're relying on the fact that we only do this transform when the shift has
3211 // exactly 2 uses and the add has exactly 1 use (otherwise, we might increase
3212 // instructions).
3213 Value *Op0 = Xor.getOperand(0), *Op1 = Xor.getOperand(1);
3214 if (Op0->hasNUses(2))
3215 std::swap(Op0, Op1);
3216
3217 Type *Ty = Xor.getType();
3218 Value *A;
3219 const APInt *ShAmt;
3220 if (match(Op1, m_AShr(m_Value(A), m_APInt(ShAmt))) &&
3221 Op1->hasNUses(2) && *ShAmt == Ty->getScalarSizeInBits() - 1 &&
3222 match(Op0, m_OneUse(m_c_Add(m_Specific(A), m_Specific(Op1))))) {
3223 // Op1 = ashr i32 A, 31 ; smear the sign bit
3224 // xor (add A, Op1), Op1 ; add -1 and flip bits if negative
3225 // --> (A < 0) ? -A : A
3226 Value *Cmp = Builder.CreateICmpSLT(A, ConstantInt::getNullValue(Ty));
3227 // Copy the nuw/nsw flags from the add to the negate.
3228 auto *Add = cast<BinaryOperator>(Op0);
3229 Value *Neg = Builder.CreateNeg(A, "", Add->hasNoUnsignedWrap(),
3230 Add->hasNoSignedWrap());
3231 return SelectInst::Create(Cmp, Neg, A);
3232 }
3233 return nullptr;
3234}
3235
3236// Transform
3237// z = (~x) &/| y
3238// into:
3239// z = ~(x |/& (~y))
3240// iff y is free to invert and all uses of z can be freely updated.
3241bool InstCombinerImpl::sinkNotIntoOtherHandOfAndOrOr(BinaryOperator &I) {
3242 Instruction::BinaryOps NewOpc;
3243 switch (I.getOpcode()) {
3244 case Instruction::And:
3245 NewOpc = Instruction::Or;
3246 break;
3247 case Instruction::Or:
3248 NewOpc = Instruction::And;
3249 break;
3250 default:
3251 return false;
3252 };
3253
3254 Value *X, *Y;
3255 if (!match(&I, m_c_BinOp(m_Not(m_Value(X)), m_Value(Y))))
3256 return false;
3257
3258 // Will we be able to fold the `not` into Y eventually?
3259 if (!InstCombiner::isFreeToInvert(Y, Y->hasOneUse()))
3260 return false;
3261
3262 // And can our users be adapted?
3263 if (!InstCombiner::canFreelyInvertAllUsersOf(&I, /*IgnoredUser=*/nullptr))
3264 return false;
3265
3266 Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
3267 Value *NewBinOp =
3268 BinaryOperator::Create(NewOpc, X, NotY, I.getName() + ".not");
3269 Builder.Insert(NewBinOp);
3270 replaceInstUsesWith(I, NewBinOp);
3271 // We can not just create an outer `not`, it will most likely be immediately
3272 // folded back, reconstructing our initial pattern, and causing an
3273 // infinite combine loop, so immediately manually fold it away.
3274 freelyInvertAllUsersOf(NewBinOp);
3275 return true;
3276}
3277
3278// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
3279// here. We should standardize that construct where it is needed or choose some
3280// other way to ensure that commutated variants of patterns are not missed.
3281Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
3282 if (Value *V = SimplifyXorInst(I.getOperand(0), I.getOperand(1),
3283 SQ.getWithInstruction(&I)))
3284 return replaceInstUsesWith(I, V);
3285
3286 if (SimplifyAssociativeOrCommutative(I))
3287 return &I;
3288
3289 if (Instruction *X = foldVectorBinop(I))
3290 return X;
3291
3292 if (Instruction *NewXor = foldXorToXor(I, Builder))
3293 return NewXor;
3294
3295 // (A&B)^(A&C) -> A&(B^C) etc
3296 if (Value *V = SimplifyUsingDistributiveLaws(I))
3297 return replaceInstUsesWith(I, V);
3298
3299 // See if we can simplify any instructions used by the instruction whose sole
3300 // purpose is to compute bits we don't care about.
3301 if (SimplifyDemandedInstructionBits(I))
3302 return &I;
3303
3304 if (Value *V = SimplifyBSwap(I, Builder))
3305 return replaceInstUsesWith(I, V);
3306
3307 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
3308 Type *Ty = I.getType();
3309
3310 // Fold (X & M) ^ (Y & ~M) -> (X & M) | (Y & ~M)
3311 // This it a special case in haveNoCommonBitsSet, but the computeKnownBits
3312 // calls in there are unnecessary as SimplifyDemandedInstructionBits should
3313 // have already taken care of those cases.
3314 Value *M;
3315 if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(M)), m_Value()),
3316 m_c_And(m_Deferred(M), m_Value()))))
3317 return BinaryOperator::CreateOr(Op0, Op1);
3318
3319 // Apply DeMorgan's Law for 'nand' / 'nor' logic with an inverted operand.
3320 Value *X, *Y;
3321
3322 // We must eliminate the and/or (one-use) for these transforms to not increase
3323 // the instruction count.
3324 // ~(~X & Y) --> (X | ~Y)
3325 // ~(Y & ~X) --> (X | ~Y)
3326 if (match(&I, m_Not(m_OneUse(m_c_And(m_Not(m_Value(X)), m_Value(Y)))))) {
3327 Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
3328 return BinaryOperator::CreateOr(X, NotY);
3329 }
3330 // ~(~X | Y) --> (X & ~Y)
3331 // ~(Y | ~X) --> (X & ~Y)
3332 if (match(&I, m_Not(m_OneUse(m_c_Or(m_Not(m_Value(X)), m_Value(Y)))))) {
3333 Value *NotY = Builder.CreateNot(Y, Y->getName() + ".not");
3334 return BinaryOperator::CreateAnd(X, NotY);
3335 }
3336
3337 if (Instruction *Xor = visitMaskedMerge(I, Builder))
3338 return Xor;
3339
3340 // Is this a 'not' (~) fed by a binary operator?
3341 BinaryOperator *NotVal;
3342 if (match(&I, m_Not(m_BinOp(NotVal)))) {
3343 if (NotVal->getOpcode() == Instruction::And ||
3344 NotVal->getOpcode() == Instruction::Or) {
3345 // Apply DeMorgan's Law when inverts are free:
3346 // ~(X & Y) --> (~X | ~Y)
3347 // ~(X | Y) --> (~X & ~Y)
3348 if (isFreeToInvert(NotVal->getOperand(0),
3349 NotVal->getOperand(0)->hasOneUse()) &&
3350 isFreeToInvert(NotVal->getOperand(1),
3351 NotVal->getOperand(1)->hasOneUse())) {
3352 Value *NotX = Builder.CreateNot(NotVal->getOperand(0), "notlhs");
3353 Value *NotY = Builder.CreateNot(NotVal->getOperand(1), "notrhs");
3354 if (NotVal->getOpcode() == Instruction::And)
3355 return BinaryOperator::CreateOr(NotX, NotY);
3356 return BinaryOperator::CreateAnd(NotX, NotY);
3357 }
3358 }
3359
3360 // ~((-X) | Y) --> (X - 1) & (~Y)
3361 if (match(NotVal,
3362 m_OneUse(m_c_Or(m_OneUse(m_Neg(m_Value(X))), m_Value(Y))))) {
3363 Value *DecX = Builder.CreateAdd(X, ConstantInt::getAllOnesValue(Ty));
3364 Value *NotY = Builder.CreateNot(Y);
3365 return BinaryOperator::CreateAnd(DecX, NotY);
3366 }
3367
3368 // ~(~X >>s Y) --> (X >>s Y)
3369 if (match(NotVal, m_AShr(m_Not(m_Value(X)), m_Value(Y))))
3370 return BinaryOperator::CreateAShr(X, Y);
3371
3372 // If we are inverting a right-shifted constant, we may be able to eliminate
3373 // the 'not' by inverting the constant and using the opposite shift type.
3374 // Canonicalization rules ensure that only a negative constant uses 'ashr',
3375 // but we must check that in case that transform has not fired yet.
3376
3377 // ~(C >>s Y) --> ~C >>u Y (when inverting the replicated sign bits)
3378 Constant *C;
3379 if (match(NotVal, m_AShr(m_Constant(C), m_Value(Y))) &&
3380 match(C, m_Negative())) {
3381 // We matched a negative constant, so propagating undef is unsafe.
3382 // Clamp undef elements to -1.
3383 Type *EltTy = Ty->getScalarType();
3384 C = Constant::replaceUndefsWith(C, ConstantInt::getAllOnesValue(EltTy));
3385 return BinaryOperator::CreateLShr(ConstantExpr::getNot(C), Y);
3386 }
3387
3388 // ~(C >>u Y) --> ~C >>s Y (when inverting the replicated sign bits)
3389 if (match(NotVal, m_LShr(m_Constant(C), m_Value(Y))) &&
3390 match(C, m_NonNegative())) {
3391 // We matched a non-negative constant, so propagating undef is unsafe.
3392 // Clamp undef elements to 0.
3393 Type *EltTy = Ty->getScalarType();
3394 C = Constant::replaceUndefsWith(C, ConstantInt::getNullValue(EltTy));
3395 return BinaryOperator::CreateAShr(ConstantExpr::getNot(C), Y);
3396 }
3397
3398 // ~(X + C) --> ~C - X
3399 if (match(NotVal, m_c_Add(m_Value(X), m_ImmConstant(C))))
3400 return BinaryOperator::CreateSub(ConstantExpr::getNot(C), X);
3401
3402 // ~(X - Y) --> ~X + Y
3403 // FIXME: is it really beneficial to sink the `not` here?
3404 if (match(NotVal, m_Sub(m_Value(X), m_Value(Y))))
3405 if (isa<Constant>(X) || NotVal->hasOneUse())
3406 return BinaryOperator::CreateAdd(Builder.CreateNot(X), Y);
3407
3408 // ~(~X + Y) --> X - Y
3409 if (match(NotVal, m_c_Add(m_Not(m_Value(X)), m_Value(Y))))
3410 return BinaryOperator::CreateWithCopiedFlags(Instruction::Sub, X, Y,
3411 NotVal);
3412 }
3413
3414 // Use DeMorgan and reassociation to eliminate a 'not' op.
3415 Constant *C1;
3416 if (match(Op1, m_Constant(C1))) {
3417 Constant *C2;
3418 if (match(Op0, m_OneUse(m_Or(m_Not(m_Value(X)), m_Constant(C2))))) {
3419 // (~X | C2) ^ C1 --> ((X & ~C2) ^ -1) ^ C1 --> (X & ~C2) ^ ~C1
3420 Value *And = Builder.CreateAnd(X, ConstantExpr::getNot(C2));
3421 return BinaryOperator::CreateXor(And, ConstantExpr::getNot(C1));
3422 }
3423 if (match(Op0, m_OneUse(m_And(m_Not(m_Value(X)), m_Constant(C2))))) {
3424 // (~X & C2) ^ C1 --> ((X | ~C2) ^ -1) ^ C1 --> (X | ~C2) ^ ~C1
3425 Value *Or = Builder.CreateOr(X, ConstantExpr::getNot(C2));
3426 return BinaryOperator::CreateXor(Or, ConstantExpr::getNot(C1));
3427 }
3428 }
3429
3430 // not (cmp A, B) = !cmp A, B
3431 CmpInst::Predicate Pred;
3432 if (match(&I, m_Not(m_OneUse(m_Cmp(Pred, m_Value(), m_Value()))))) {
3433 cast<CmpInst>(Op0)->setPredicate(CmpInst::getInversePredicate(Pred));
3434 return replaceInstUsesWith(I, Op0);
3435 }
3436
3437 {
3438 const APInt *RHSC;
3439 if (match(Op1, m_APInt(RHSC))) {
3440 Value *X;
3441 const APInt *C;
3442 // (C - X) ^ signmaskC --> (C + signmaskC) - X
3443 if (RHSC->isSignMask() && match(Op0, m_Sub(m_APInt(C), m_Value(X))))
3444 return BinaryOperator::CreateSub(ConstantInt::get(Ty, *C + *RHSC), X);
3445
3446 // (X + C) ^ signmaskC --> X + (C + signmaskC)
3447 if (RHSC->isSignMask() && match(Op0, m_Add(m_Value(X), m_APInt(C))))
3448 return BinaryOperator::CreateAdd(X, ConstantInt::get(Ty, *C + *RHSC));
3449
3450 // (X | C) ^ RHSC --> X ^ (C ^ RHSC) iff X & C == 0
3451 if (match(Op0, m_Or(m_Value(X), m_APInt(C))) &&
3452 MaskedValueIsZero(X, *C, 0, &I))
3453 return BinaryOperator::CreateXor(X, ConstantInt::get(Ty, *C ^ *RHSC));
3454
3455 // If RHSC is inverting the remaining bits of shifted X,
3456 // canonicalize to a 'not' before the shift to help SCEV and codegen:
3457 // (X << C) ^ RHSC --> ~X << C
3458 if (match(Op0, m_OneUse(m_Shl(m_Value(X), m_APInt(C)))) &&
3459 *RHSC == APInt::getAllOnesValue(Ty->getScalarSizeInBits()).shl(*C)) {
3460 Value *NotX = Builder.CreateNot(X);
3461 return BinaryOperator::CreateShl(NotX, ConstantInt::get(Ty, *C));
3462 }
3463 // (X >>u C) ^ RHSC --> ~X >>u C
3464 if (match(Op0, m_OneUse(m_LShr(m_Value(X), m_APInt(C)))) &&
3465 *RHSC == APInt::getAllOnesValue(Ty->getScalarSizeInBits()).lshr(*C)) {
3466 Value *NotX = Builder.CreateNot(X);
3467 return BinaryOperator::CreateLShr(NotX, ConstantInt::get(Ty, *C));
3468 }
3469 // TODO: We could handle 'ashr' here as well. That would be matching
3470 // a 'not' op and moving it before the shift. Doing that requires
3471 // preventing the inverse fold in canShiftBinOpWithConstantRHS().
3472 }
3473 }
3474
3475 // FIXME: This should not be limited to scalar (pull into APInt match above).
3476 {
3477 Value *X;
3478 ConstantInt *C1, *C2, *C3;
3479 // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
3480 if (match(Op1, m_ConstantInt(C3)) &&
3481 match(Op0, m_LShr(m_Xor(m_Value(X), m_ConstantInt(C1)),
3482 m_ConstantInt(C2))) &&
3483 Op0->hasOneUse()) {
3484 // fold (C1 >> C2) ^ C3
3485 APInt FoldConst = C1->getValue().lshr(C2->getValue());
3486 FoldConst ^= C3->getValue();
3487 // Prepare the two operands.
3488 auto *Opnd0 = cast<Instruction>(Builder.CreateLShr(X, C2));
3489 Opnd0->takeName(cast<Instruction>(Op0));
3490 Opnd0->setDebugLoc(I.getDebugLoc());
3491 return BinaryOperator::CreateXor(Opnd0, ConstantInt::get(Ty, FoldConst));
3492 }
3493 }
3494
3495 if (Instruction *FoldedLogic = foldBinOpIntoSelectOrPhi(I))
3496 return FoldedLogic;
3497
3498 // Y ^ (X | Y) --> X & ~Y
3499 // Y ^ (Y | X) --> X & ~Y
3500 if (match(Op1, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op0)))))
3501 return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op0));
3502 // (X | Y) ^ Y --> X & ~Y
3503 // (Y | X) ^ Y --> X & ~Y
3504 if (match(Op0, m_OneUse(m_c_Or(m_Value(X), m_Specific(Op1)))))
3505 return BinaryOperator::CreateAnd(X, Builder.CreateNot(Op1));
3506
3507 // Y ^ (X & Y) --> ~X & Y
3508 // Y ^ (Y & X) --> ~X & Y
3509 if (match(Op1, m_OneUse(m_c_And(m_Value(X), m_Specific(Op0)))))
3510 return BinaryOperator::CreateAnd(Op0, Builder.CreateNot(X));
3511 // (X & Y) ^ Y --> ~X & Y
3512 // (Y & X) ^ Y --> ~X & Y
3513 // Canonical form is (X & C) ^ C; don't touch that.
3514 // TODO: A 'not' op is better for analysis and codegen, but demanded bits must
3515 // be fixed to prefer that (otherwise we get infinite looping).
3516 if (!match(Op1, m_Constant()) &&
3517 match(Op0, m_OneUse(m_c_And(m_Value(X), m_Specific(Op1)))))
3518 return BinaryOperator::CreateAnd(Op1, Builder.CreateNot(X));
3519
3520 Value *A, *B, *C;
3521 // (A ^ B) ^ (A | C) --> (~A & C) ^ B -- There are 4 commuted variants.
3522 if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))),
3523 m_OneUse(m_c_Or(m_Deferred(A), m_Value(C))))))
3524 return BinaryOperator::CreateXor(
3525 Builder.CreateAnd(Builder.CreateNot(A), C), B);
3526
3527 // (A ^ B) ^ (B | C) --> (~B & C) ^ A -- There are 4 commuted variants.
3528 if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_Value(A), m_Value(B))),
3529 m_OneUse(m_c_Or(m_Deferred(B), m_Value(C))))))
3530 return BinaryOperator::CreateXor(
3531 Builder.CreateAnd(Builder.CreateNot(B), C), A);
3532
3533 // (A & B) ^ (A ^ B) -> (A | B)
3534 if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
3535 match(Op1, m_c_Xor(m_Specific(A), m_Specific(B))))
3536 return BinaryOperator::CreateOr(A, B);
3537 // (A ^ B) ^ (A & B) -> (A | B)
3538 if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
3539 match(Op1, m_c_And(m_Specific(A), m_Specific(B))))
3540 return BinaryOperator::CreateOr(A, B);
3541
3542 // (A & ~B) ^ ~A -> ~(A & B)
3543 // (~B & A) ^ ~A -> ~(A & B)
3544 if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) &&
3545 match(Op1, m_Not(m_Specific(A))))
3546 return BinaryOperator::CreateNot(Builder.CreateAnd(A, B));
3547
3548 // (~A & B) ^ A --> A | B -- There are 4 commuted variants.
3549 if (match(&I, m_c_Xor(m_c_And(m_Not(m_Value(A)), m_Value(B)), m_Deferred(A))))
3550 return BinaryOperator::CreateOr(A, B);
3551
3552 // (A | B) ^ (A | C) --> (B ^ C) & ~A -- There are 4 commuted variants.
3553 // TODO: Loosen one-use restriction if common operand is a constant.
3554 Value *D;
3555 if (match(Op0, m_OneUse(m_Or(m_Value(A), m_Value(B)))) &&
3556 match(Op1, m_OneUse(m_Or(m_Value(C), m_Value(D))))) {
3557 if (B == C || B == D)
3558 std::swap(A, B);
3559 if (A == C)
3560 std::swap(C, D);
3561 if (A == D) {
3562 Value *NotA = Builder.CreateNot(A);
3563 return BinaryOperator::CreateAnd(Builder.CreateXor(B, C), NotA);
3564 }
3565 }
3566
3567 if (auto *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
3568 if (auto *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
3569 if (Value *V = foldXorOfICmps(LHS, RHS, I))
3570 return replaceInstUsesWith(I, V);
3571
3572 if (Instruction *CastedXor = foldCastedBitwiseLogic(I))
3573 return CastedXor;
3574
3575 // Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max:
3576 // ~min(~X, ~Y) --> max(X, Y)
3577 // ~max(~X, Y) --> min(X, ~Y)
3578 auto *II = dyn_cast<IntrinsicInst>(Op0);
3579 if (II && II->hasOneUse() && match(Op1, m_AllOnes())) {
3580 if (match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y))) &&
3581 isFreeToInvert(X, X->hasOneUse()) &&
3582 isFreeToInvert(Y, Y->hasOneUse())) {
3583 Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
3584 Value *NotX = Builder.CreateNot(X);
3585 Value *NotY = Builder.CreateNot(Y);
3586 Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, NotX, NotY);
3587 return replaceInstUsesWith(I, InvMaxMin);
3588 }
3589 if (match(Op0, m_c_MaxOrMin(m_Not(m_Value(X)), m_Value(Y)))) {
3590 Intrinsic::ID InvID = getInverseMinMaxIntrinsic(II->getIntrinsicID());
3591 Value *NotY = Builder.CreateNot(Y);
3592 Value *InvMaxMin = Builder.CreateBinaryIntrinsic(InvID, X, NotY);
3593 return replaceInstUsesWith(I, InvMaxMin);
3594 }
3595 }
3596
3597 // TODO: Remove folds if we canonicalize to intrinsics (see above).
3598 // Eliminate a bitwise 'not' op of 'not' min/max by inverting the min/max:
3599 //
3600 // %notx = xor i32 %x, -1
3601 // %cmp1 = icmp sgt i32 %notx, %y
3602 // %smax = select i1 %cmp1, i32 %notx, i32 %y
3603 // %res = xor i32 %smax, -1
3604 // =>
3605 // %noty = xor i32 %y, -1
3606 // %cmp2 = icmp slt %x, %noty
3607 // %res = select i1 %cmp2, i32 %x, i32 %noty
3608 //
3609 // Same is applicable for smin/umax/umin.
3610 if (match(Op1, m_AllOnes()) && Op0->hasOneUse()) {
3611 Value *LHS, *RHS;
3612 SelectPatternFlavor SPF = matchSelectPattern(Op0, LHS, RHS).Flavor;
3613 if (SelectPatternResult::isMinOrMax(SPF)) {
3614 // It's possible we get here before the not has been simplified, so make
3615 // sure the input to the not isn't freely invertible.
3616 if (match(LHS, m_Not(m_Value(X))) && !isFreeToInvert(X, X->hasOneUse())) {
3617 Value *NotY = Builder.CreateNot(RHS);
3618 return SelectInst::Create(
3619 Builder.CreateICmp(getInverseMinMaxPred(SPF), X, NotY), X, NotY);
3620 }
3621
3622 // It's possible we get here before the not has been simplified, so make
3623 // sure the input to the not isn't freely invertible.
3624 if (match(RHS, m_Not(m_Value(Y))) && !isFreeToInvert(Y, Y->hasOneUse())) {
3625 Value *NotX = Builder.CreateNot(LHS);
3626 return SelectInst::Create(
3627 Builder.CreateICmp(getInverseMinMaxPred(SPF), NotX, Y), NotX, Y);
3628 }
3629
3630 // If both sides are freely invertible, then we can get rid of the xor
3631 // completely.
3632 if (isFreeToInvert(LHS, !LHS->hasNUsesOrMore(3)) &&
3633 isFreeToInvert(RHS, !RHS->hasNUsesOrMore(3))) {
3634 Value *NotLHS = Builder.CreateNot(LHS);
3635 Value *NotRHS = Builder.CreateNot(RHS);
3636 return SelectInst::Create(
3637 Builder.CreateICmp(getInverseMinMaxPred(SPF), NotLHS, NotRHS),
3638 NotLHS, NotRHS);
3639 }
3640 }
3641
3642 // Pull 'not' into operands of select if both operands are one-use compares
3643 // or one is one-use compare and the other one is a constant.
3644 // Inverting the predicates eliminates the 'not' operation.
3645 // Example:
3646 // not (select ?, (cmp TPred, ?, ?), (cmp FPred, ?, ?) -->
3647 // select ?, (cmp InvTPred, ?, ?), (cmp InvFPred, ?, ?)
3648 // not (select ?, (cmp TPred, ?, ?), true -->
3649 // select ?, (cmp InvTPred, ?, ?), false
3650 if (auto *Sel = dyn_cast<SelectInst>(Op0)) {
3651 Value *TV = Sel->getTrueValue();
3652 Value *FV = Sel->getFalseValue();
3653 auto *CmpT = dyn_cast<CmpInst>(TV);
3654 auto *CmpF = dyn_cast<CmpInst>(FV);
3655 bool InvertibleT = (CmpT && CmpT->hasOneUse()) || isa<Constant>(TV);
3656 bool InvertibleF = (CmpF && CmpF->hasOneUse()) || isa<Constant>(FV);
3657 if (InvertibleT && InvertibleF) {
3658 if (CmpT)
3659 CmpT->setPredicate(CmpT->getInversePredicate());
3660 else
3661 Sel->setTrueValue(ConstantExpr::getNot(cast<Constant>(TV)));
3662 if (CmpF)
3663 CmpF->setPredicate(CmpF->getInversePredicate());
3664 else
3665 Sel->setFalseValue(ConstantExpr::getNot(cast<Constant>(FV)));
3666 return replaceInstUsesWith(I, Sel);
3667 }
3668 }
3669 }
3670
3671 if (Instruction *NewXor = sinkNotIntoXor(I, Builder))
3672 return NewXor;
3673
3674 if (Instruction *Abs = canonicalizeAbs(I, Builder))
3675 return Abs;
3676
3677 // Otherwise, if all else failed, try to hoist the xor-by-constant:
3678 // (X ^ C) ^ Y --> (X ^ Y) ^ C
3679 // Just like we do in other places, we completely avoid the fold
3680 // for constantexprs, at least to avoid endless combine loop.
3681 if (match(&I, m_c_Xor(m_OneUse(m_Xor(m_CombineAnd(m_Value(X),
3682 m_Unless(m_ConstantExpr())),
3683 m_ImmConstant(C1))),
3684 m_Value(Y))))
3685 return BinaryOperator::CreateXor(Builder.CreateXor(X, Y), C1);
3686
3687 return nullptr;
3688}