1 //===- InstCombineAndOrXor.cpp --------------------------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the visitAnd, visitOr, and visitXor functions.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "InstCombine.h"
15 #include "llvm/Intrinsics.h"
16 #include "llvm/Analysis/InstructionSimplify.h"
17 #include "llvm/Support/ConstantRange.h"
18 #include "llvm/Support/PatternMatch.h"
19 using namespace llvm;
20 using namespace PatternMatch;
21
22
23 /// AddOne - Add one to a ConstantInt.
AddOne(Constant * C)24 static Constant *AddOne(Constant *C) {
25 return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
26 }
27 /// SubOne - Subtract one from a ConstantInt.
SubOne(ConstantInt * C)28 static Constant *SubOne(ConstantInt *C) {
29 return ConstantInt::get(C->getContext(), C->getValue()-1);
30 }
31
32 /// isFreeToInvert - Return true if the specified value is free to invert (apply
33 /// ~ to). This happens in cases where the ~ can be eliminated.
isFreeToInvert(Value * V)34 static inline bool isFreeToInvert(Value *V) {
35 // ~(~(X)) -> X.
36 if (BinaryOperator::isNot(V))
37 return true;
38
39 // Constants can be considered to be not'ed values.
40 if (isa<ConstantInt>(V))
41 return true;
42
43 // Compares can be inverted if they have a single use.
44 if (CmpInst *CI = dyn_cast<CmpInst>(V))
45 return CI->hasOneUse();
46
47 return false;
48 }
49
dyn_castNotVal(Value * V)50 static inline Value *dyn_castNotVal(Value *V) {
51 // If this is not(not(x)) don't return that this is a not: we want the two
52 // not's to be folded first.
53 if (BinaryOperator::isNot(V)) {
54 Value *Operand = BinaryOperator::getNotArgument(V);
55 if (!isFreeToInvert(Operand))
56 return Operand;
57 }
58
59 // Constants can be considered to be not'ed values...
60 if (ConstantInt *C = dyn_cast<ConstantInt>(V))
61 return ConstantInt::get(C->getType(), ~C->getValue());
62 return 0;
63 }
64
65
66 /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
67 /// are carefully arranged to allow folding of expressions such as:
68 ///
69 /// (A < B) | (A > B) --> (A != B)
70 ///
71 /// Note that this is only valid if the first and second predicates have the
72 /// same sign. Is illegal to do: (A u< B) | (A s> B)
73 ///
74 /// Three bits are used to represent the condition, as follows:
75 /// 0 A > B
76 /// 1 A == B
77 /// 2 A < B
78 ///
79 /// <=> Value Definition
80 /// 000 0 Always false
81 /// 001 1 A > B
82 /// 010 2 A == B
83 /// 011 3 A >= B
84 /// 100 4 A < B
85 /// 101 5 A != B
86 /// 110 6 A <= B
87 /// 111 7 Always true
88 ///
getICmpCode(const ICmpInst * ICI)89 static unsigned getICmpCode(const ICmpInst *ICI) {
90 switch (ICI->getPredicate()) {
91 // False -> 0
92 case ICmpInst::ICMP_UGT: return 1; // 001
93 case ICmpInst::ICMP_SGT: return 1; // 001
94 case ICmpInst::ICMP_EQ: return 2; // 010
95 case ICmpInst::ICMP_UGE: return 3; // 011
96 case ICmpInst::ICMP_SGE: return 3; // 011
97 case ICmpInst::ICMP_ULT: return 4; // 100
98 case ICmpInst::ICMP_SLT: return 4; // 100
99 case ICmpInst::ICMP_NE: return 5; // 101
100 case ICmpInst::ICMP_ULE: return 6; // 110
101 case ICmpInst::ICMP_SLE: return 6; // 110
102 // True -> 7
103 default:
104 llvm_unreachable("Invalid ICmp predicate!");
105 return 0;
106 }
107 }
108
109 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
110 /// predicate into a three bit mask. It also returns whether it is an ordered
111 /// predicate by reference.
getFCmpCode(FCmpInst::Predicate CC,bool & isOrdered)112 static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
113 isOrdered = false;
114 switch (CC) {
115 case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
116 case FCmpInst::FCMP_UNO: return 0; // 000
117 case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
118 case FCmpInst::FCMP_UGT: return 1; // 001
119 case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
120 case FCmpInst::FCMP_UEQ: return 2; // 010
121 case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
122 case FCmpInst::FCMP_UGE: return 3; // 011
123 case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
124 case FCmpInst::FCMP_ULT: return 4; // 100
125 case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
126 case FCmpInst::FCMP_UNE: return 5; // 101
127 case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
128 case FCmpInst::FCMP_ULE: return 6; // 110
129 // True -> 7
130 default:
131 // Not expecting FCMP_FALSE and FCMP_TRUE;
132 llvm_unreachable("Unexpected FCmp predicate!");
133 return 0;
134 }
135 }
136
137 /// getICmpValue - This is the complement of getICmpCode, which turns an
138 /// opcode and two operands into either a constant true or false, or a brand
139 /// new ICmp instruction. The sign is passed in to determine which kind
140 /// of predicate to use in the new icmp instruction.
getICmpValue(bool Sign,unsigned Code,Value * LHS,Value * RHS,InstCombiner::BuilderTy * Builder)141 static Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
142 InstCombiner::BuilderTy *Builder) {
143 CmpInst::Predicate Pred;
144 switch (Code) {
145 default: assert(0 && "Illegal ICmp code!");
146 case 0: // False.
147 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
148 case 1: Pred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
149 case 2: Pred = ICmpInst::ICMP_EQ; break;
150 case 3: Pred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
151 case 4: Pred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
152 case 5: Pred = ICmpInst::ICMP_NE; break;
153 case 6: Pred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
154 case 7: // True.
155 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
156 }
157 return Builder->CreateICmp(Pred, LHS, RHS);
158 }
159
160 /// getFCmpValue - This is the complement of getFCmpCode, which turns an
161 /// opcode and two operands into either a FCmp instruction. isordered is passed
162 /// in to determine which kind of predicate to use in the new fcmp instruction.
getFCmpValue(bool isordered,unsigned code,Value * LHS,Value * RHS,InstCombiner::BuilderTy * Builder)163 static Value *getFCmpValue(bool isordered, unsigned code,
164 Value *LHS, Value *RHS,
165 InstCombiner::BuilderTy *Builder) {
166 CmpInst::Predicate Pred;
167 switch (code) {
168 default: assert(0 && "Illegal FCmp code!");
169 case 0: Pred = isordered ? FCmpInst::FCMP_ORD : FCmpInst::FCMP_UNO; break;
170 case 1: Pred = isordered ? FCmpInst::FCMP_OGT : FCmpInst::FCMP_UGT; break;
171 case 2: Pred = isordered ? FCmpInst::FCMP_OEQ : FCmpInst::FCMP_UEQ; break;
172 case 3: Pred = isordered ? FCmpInst::FCMP_OGE : FCmpInst::FCMP_UGE; break;
173 case 4: Pred = isordered ? FCmpInst::FCMP_OLT : FCmpInst::FCMP_ULT; break;
174 case 5: Pred = isordered ? FCmpInst::FCMP_ONE : FCmpInst::FCMP_UNE; break;
175 case 6: Pred = isordered ? FCmpInst::FCMP_OLE : FCmpInst::FCMP_ULE; break;
176 case 7:
177 if (!isordered) return ConstantInt::getTrue(LHS->getContext());
178 Pred = FCmpInst::FCMP_ORD; break;
179 }
180 return Builder->CreateFCmp(Pred, LHS, RHS);
181 }
182
183 /// PredicatesFoldable - Return true if both predicates match sign or if at
184 /// least one of them is an equality comparison (which is signless).
PredicatesFoldable(ICmpInst::Predicate p1,ICmpInst::Predicate p2)185 static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
186 return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
187 (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
188 (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
189 }
190
191 // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
192 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
193 // guaranteed to be a binary operator.
OptAndOp(Instruction * Op,ConstantInt * OpRHS,ConstantInt * AndRHS,BinaryOperator & TheAnd)194 Instruction *InstCombiner::OptAndOp(Instruction *Op,
195 ConstantInt *OpRHS,
196 ConstantInt *AndRHS,
197 BinaryOperator &TheAnd) {
198 Value *X = Op->getOperand(0);
199 Constant *Together = 0;
200 if (!Op->isShift())
201 Together = ConstantExpr::getAnd(AndRHS, OpRHS);
202
203 switch (Op->getOpcode()) {
204 case Instruction::Xor:
205 if (Op->hasOneUse()) {
206 // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
207 Value *And = Builder->CreateAnd(X, AndRHS);
208 And->takeName(Op);
209 return BinaryOperator::CreateXor(And, Together);
210 }
211 break;
212 case Instruction::Or:
213 if (Op->hasOneUse()){
214 if (Together != OpRHS) {
215 // (X | C1) & C2 --> (X | (C1&C2)) & C2
216 Value *Or = Builder->CreateOr(X, Together);
217 Or->takeName(Op);
218 return BinaryOperator::CreateAnd(Or, AndRHS);
219 }
220
221 ConstantInt *TogetherCI = dyn_cast<ConstantInt>(Together);
222 if (TogetherCI && !TogetherCI->isZero()){
223 // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1
224 // NOTE: This reduces the number of bits set in the & mask, which
225 // can expose opportunities for store narrowing.
226 Together = ConstantExpr::getXor(AndRHS, Together);
227 Value *And = Builder->CreateAnd(X, Together);
228 And->takeName(Op);
229 return BinaryOperator::CreateOr(And, OpRHS);
230 }
231 }
232
233 break;
234 case Instruction::Add:
235 if (Op->hasOneUse()) {
236 // Adding a one to a single bit bit-field should be turned into an XOR
237 // of the bit. First thing to check is to see if this AND is with a
238 // single bit constant.
239 const APInt &AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
240
241 // If there is only one bit set.
242 if (AndRHSV.isPowerOf2()) {
243 // Ok, at this point, we know that we are masking the result of the
244 // ADD down to exactly one bit. If the constant we are adding has
245 // no bits set below this bit, then we can eliminate the ADD.
246 const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
247
248 // Check to see if any bits below the one bit set in AndRHSV are set.
249 if ((AddRHS & (AndRHSV-1)) == 0) {
250 // If not, the only thing that can effect the output of the AND is
251 // the bit specified by AndRHSV. If that bit is set, the effect of
252 // the XOR is to toggle the bit. If it is clear, then the ADD has
253 // no effect.
254 if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
255 TheAnd.setOperand(0, X);
256 return &TheAnd;
257 } else {
258 // Pull the XOR out of the AND.
259 Value *NewAnd = Builder->CreateAnd(X, AndRHS);
260 NewAnd->takeName(Op);
261 return BinaryOperator::CreateXor(NewAnd, AndRHS);
262 }
263 }
264 }
265 }
266 break;
267
268 case Instruction::Shl: {
269 // We know that the AND will not produce any of the bits shifted in, so if
270 // the anded constant includes them, clear them now!
271 //
272 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
273 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
274 APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
275 ConstantInt *CI = ConstantInt::get(AndRHS->getContext(),
276 AndRHS->getValue() & ShlMask);
277
278 if (CI->getValue() == ShlMask)
279 // Masking out bits that the shift already masks.
280 return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
281
282 if (CI != AndRHS) { // Reducing bits set in and.
283 TheAnd.setOperand(1, CI);
284 return &TheAnd;
285 }
286 break;
287 }
288 case Instruction::LShr: {
289 // We know that the AND will not produce any of the bits shifted in, so if
290 // the anded constant includes them, clear them now! This only applies to
291 // unsigned shifts, because a signed shr may bring in set bits!
292 //
293 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
294 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
295 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
296 ConstantInt *CI = ConstantInt::get(Op->getContext(),
297 AndRHS->getValue() & ShrMask);
298
299 if (CI->getValue() == ShrMask)
300 // Masking out bits that the shift already masks.
301 return ReplaceInstUsesWith(TheAnd, Op);
302
303 if (CI != AndRHS) {
304 TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
305 return &TheAnd;
306 }
307 break;
308 }
309 case Instruction::AShr:
310 // Signed shr.
311 // See if this is shifting in some sign extension, then masking it out
312 // with an and.
313 if (Op->hasOneUse()) {
314 uint32_t BitWidth = AndRHS->getType()->getBitWidth();
315 uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
316 APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
317 Constant *C = ConstantInt::get(Op->getContext(),
318 AndRHS->getValue() & ShrMask);
319 if (C == AndRHS) { // Masking out bits shifted in.
320 // (Val ashr C1) & C2 -> (Val lshr C1) & C2
321 // Make the argument unsigned.
322 Value *ShVal = Op->getOperand(0);
323 ShVal = Builder->CreateLShr(ShVal, OpRHS, Op->getName());
324 return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
325 }
326 }
327 break;
328 }
329 return 0;
330 }
331
332
333 /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
334 /// true, otherwise (V < Lo || V >= Hi). In practice, we emit the more efficient
335 /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
336 /// whether to treat the V, Lo and HI as signed or not. IB is the location to
337 /// insert new instructions.
InsertRangeTest(Value * V,Constant * Lo,Constant * Hi,bool isSigned,bool Inside)338 Value *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
339 bool isSigned, bool Inside) {
340 assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
341 ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
342 "Lo is not <= Hi in range emission code!");
343
344 if (Inside) {
345 if (Lo == Hi) // Trivially false.
346 return ConstantInt::getFalse(V->getContext());
347
348 // V >= Min && V < Hi --> V < Hi
349 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
350 ICmpInst::Predicate pred = (isSigned ?
351 ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
352 return Builder->CreateICmp(pred, V, Hi);
353 }
354
355 // Emit V-Lo <u Hi-Lo
356 Constant *NegLo = ConstantExpr::getNeg(Lo);
357 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
358 Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
359 return Builder->CreateICmpULT(Add, UpperBound);
360 }
361
362 if (Lo == Hi) // Trivially true.
363 return ConstantInt::getTrue(V->getContext());
364
365 // V < Min || V >= Hi -> V > Hi-1
366 Hi = SubOne(cast<ConstantInt>(Hi));
367 if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
368 ICmpInst::Predicate pred = (isSigned ?
369 ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
370 return Builder->CreateICmp(pred, V, Hi);
371 }
372
373 // Emit V-Lo >u Hi-1-Lo
374 // Note that Hi has already had one subtracted from it, above.
375 ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
376 Value *Add = Builder->CreateAdd(V, NegLo, V->getName()+".off");
377 Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
378 return Builder->CreateICmpUGT(Add, LowerBound);
379 }
380
381 // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
382 // any number of 0s on either side. The 1s are allowed to wrap from LSB to
383 // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
384 // not, since all 1s are not contiguous.
isRunOfOnes(ConstantInt * Val,uint32_t & MB,uint32_t & ME)385 static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
386 const APInt& V = Val->getValue();
387 uint32_t BitWidth = Val->getType()->getBitWidth();
388 if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
389
390 // look for the first zero bit after the run of ones
391 MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
392 // look for the first non-zero bit
393 ME = V.getActiveBits();
394 return true;
395 }
396
397 /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
398 /// where isSub determines whether the operator is a sub. If we can fold one of
399 /// the following xforms:
400 ///
401 /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
402 /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
403 /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
404 ///
405 /// return (A +/- B).
406 ///
FoldLogicalPlusAnd(Value * LHS,Value * RHS,ConstantInt * Mask,bool isSub,Instruction & I)407 Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
408 ConstantInt *Mask, bool isSub,
409 Instruction &I) {
410 Instruction *LHSI = dyn_cast<Instruction>(LHS);
411 if (!LHSI || LHSI->getNumOperands() != 2 ||
412 !isa<ConstantInt>(LHSI->getOperand(1))) return 0;
413
414 ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
415
416 switch (LHSI->getOpcode()) {
417 default: return 0;
418 case Instruction::And:
419 if (ConstantExpr::getAnd(N, Mask) == Mask) {
420 // If the AndRHS is a power of two minus one (0+1+), this is simple.
421 if ((Mask->getValue().countLeadingZeros() +
422 Mask->getValue().countPopulation()) ==
423 Mask->getValue().getBitWidth())
424 break;
425
426 // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
427 // part, we don't need any explicit masks to take them out of A. If that
428 // is all N is, ignore it.
429 uint32_t MB = 0, ME = 0;
430 if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
431 uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
432 APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
433 if (MaskedValueIsZero(RHS, Mask))
434 break;
435 }
436 }
437 return 0;
438 case Instruction::Or:
439 case Instruction::Xor:
440 // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
441 if ((Mask->getValue().countLeadingZeros() +
442 Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
443 && ConstantExpr::getAnd(N, Mask)->isNullValue())
444 break;
445 return 0;
446 }
447
448 if (isSub)
449 return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
450 return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
451 }
452
453 /// enum for classifying (icmp eq (A & B), C) and (icmp ne (A & B), C)
454 /// One of A and B is considered the mask, the other the value. This is
455 /// described as the "AMask" or "BMask" part of the enum. If the enum
456 /// contains only "Mask", then both A and B can be considered masks.
457 /// If A is the mask, then it was proven, that (A & C) == C. This
458 /// is trivial if C == A, or C == 0. If both A and C are constants, this
459 /// proof is also easy.
460 /// For the following explanations we assume that A is the mask.
461 /// The part "AllOnes" declares, that the comparison is true only
462 /// if (A & B) == A, or all bits of A are set in B.
463 /// Example: (icmp eq (A & 3), 3) -> FoldMskICmp_AMask_AllOnes
464 /// The part "AllZeroes" declares, that the comparison is true only
465 /// if (A & B) == 0, or all bits of A are cleared in B.
466 /// Example: (icmp eq (A & 3), 0) -> FoldMskICmp_Mask_AllZeroes
467 /// The part "Mixed" declares, that (A & B) == C and C might or might not
468 /// contain any number of one bits and zero bits.
469 /// Example: (icmp eq (A & 3), 1) -> FoldMskICmp_AMask_Mixed
470 /// The Part "Not" means, that in above descriptions "==" should be replaced
471 /// by "!=".
472 /// Example: (icmp ne (A & 3), 3) -> FoldMskICmp_AMask_NotAllOnes
473 /// If the mask A contains a single bit, then the following is equivalent:
474 /// (icmp eq (A & B), A) equals (icmp ne (A & B), 0)
475 /// (icmp ne (A & B), A) equals (icmp eq (A & B), 0)
476 enum MaskedICmpType {
477 FoldMskICmp_AMask_AllOnes = 1,
478 FoldMskICmp_AMask_NotAllOnes = 2,
479 FoldMskICmp_BMask_AllOnes = 4,
480 FoldMskICmp_BMask_NotAllOnes = 8,
481 FoldMskICmp_Mask_AllZeroes = 16,
482 FoldMskICmp_Mask_NotAllZeroes = 32,
483 FoldMskICmp_AMask_Mixed = 64,
484 FoldMskICmp_AMask_NotMixed = 128,
485 FoldMskICmp_BMask_Mixed = 256,
486 FoldMskICmp_BMask_NotMixed = 512
487 };
488
489 /// return the set of pattern classes (from MaskedICmpType)
490 /// that (icmp SCC (A & B), C) satisfies
getTypeOfMaskedICmp(Value * A,Value * B,Value * C,ICmpInst::Predicate SCC)491 static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C,
492 ICmpInst::Predicate SCC)
493 {
494 ConstantInt *ACst = dyn_cast<ConstantInt>(A);
495 ConstantInt *BCst = dyn_cast<ConstantInt>(B);
496 ConstantInt *CCst = dyn_cast<ConstantInt>(C);
497 bool icmp_eq = (SCC == ICmpInst::ICMP_EQ);
498 bool icmp_abit = (ACst != 0 && !ACst->isZero() &&
499 ACst->getValue().isPowerOf2());
500 bool icmp_bbit = (BCst != 0 && !BCst->isZero() &&
501 BCst->getValue().isPowerOf2());
502 unsigned result = 0;
503 if (CCst != 0 && CCst->isZero()) {
504 // if C is zero, then both A and B qualify as mask
505 result |= (icmp_eq ? (FoldMskICmp_Mask_AllZeroes |
506 FoldMskICmp_Mask_AllZeroes |
507 FoldMskICmp_AMask_Mixed |
508 FoldMskICmp_BMask_Mixed)
509 : (FoldMskICmp_Mask_NotAllZeroes |
510 FoldMskICmp_Mask_NotAllZeroes |
511 FoldMskICmp_AMask_NotMixed |
512 FoldMskICmp_BMask_NotMixed));
513 if (icmp_abit)
514 result |= (icmp_eq ? (FoldMskICmp_AMask_NotAllOnes |
515 FoldMskICmp_AMask_NotMixed)
516 : (FoldMskICmp_AMask_AllOnes |
517 FoldMskICmp_AMask_Mixed));
518 if (icmp_bbit)
519 result |= (icmp_eq ? (FoldMskICmp_BMask_NotAllOnes |
520 FoldMskICmp_BMask_NotMixed)
521 : (FoldMskICmp_BMask_AllOnes |
522 FoldMskICmp_BMask_Mixed));
523 return result;
524 }
525 if (A == C) {
526 result |= (icmp_eq ? (FoldMskICmp_AMask_AllOnes |
527 FoldMskICmp_AMask_Mixed)
528 : (FoldMskICmp_AMask_NotAllOnes |
529 FoldMskICmp_AMask_NotMixed));
530 if (icmp_abit)
531 result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
532 FoldMskICmp_AMask_NotMixed)
533 : (FoldMskICmp_Mask_AllZeroes |
534 FoldMskICmp_AMask_Mixed));
535 }
536 else if (ACst != 0 && CCst != 0 &&
537 ConstantExpr::getAnd(ACst, CCst) == CCst) {
538 result |= (icmp_eq ? FoldMskICmp_AMask_Mixed
539 : FoldMskICmp_AMask_NotMixed);
540 }
541 if (B == C)
542 {
543 result |= (icmp_eq ? (FoldMskICmp_BMask_AllOnes |
544 FoldMskICmp_BMask_Mixed)
545 : (FoldMskICmp_BMask_NotAllOnes |
546 FoldMskICmp_BMask_NotMixed));
547 if (icmp_bbit)
548 result |= (icmp_eq ? (FoldMskICmp_Mask_NotAllZeroes |
549 FoldMskICmp_BMask_NotMixed)
550 : (FoldMskICmp_Mask_AllZeroes |
551 FoldMskICmp_BMask_Mixed));
552 }
553 else if (BCst != 0 && CCst != 0 &&
554 ConstantExpr::getAnd(BCst, CCst) == CCst) {
555 result |= (icmp_eq ? FoldMskICmp_BMask_Mixed
556 : FoldMskICmp_BMask_NotMixed);
557 }
558 return result;
559 }
560
561 /// foldLogOpOfMaskedICmpsHelper:
562 /// handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
563 /// return the set of pattern classes (from MaskedICmpType)
564 /// that both LHS and RHS satisfy
foldLogOpOfMaskedICmpsHelper(Value * & A,Value * & B,Value * & C,Value * & D,Value * & E,ICmpInst * LHS,ICmpInst * RHS)565 static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
566 Value*& B, Value*& C,
567 Value*& D, Value*& E,
568 ICmpInst *LHS, ICmpInst *RHS) {
569 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
570 if (LHSCC != ICmpInst::ICMP_EQ && LHSCC != ICmpInst::ICMP_NE) return 0;
571 if (RHSCC != ICmpInst::ICMP_EQ && RHSCC != ICmpInst::ICMP_NE) return 0;
572 if (LHS->getOperand(0)->getType() != RHS->getOperand(0)->getType()) return 0;
573 // vectors are not (yet?) supported
574 if (LHS->getOperand(0)->getType()->isVectorTy()) return 0;
575
576 // Here comes the tricky part:
577 // LHS might be of the form L11 & L12 == X, X == L21 & L22,
578 // and L11 & L12 == L21 & L22. The same goes for RHS.
579 // Now we must find those components L** and R**, that are equal, so
580 // that we can extract the parameters A, B, C, D, and E for the canonical
581 // above.
582 Value *L1 = LHS->getOperand(0);
583 Value *L2 = LHS->getOperand(1);
584 Value *L11,*L12,*L21,*L22;
585 if (match(L1, m_And(m_Value(L11), m_Value(L12)))) {
586 if (!match(L2, m_And(m_Value(L21), m_Value(L22))))
587 L21 = L22 = 0;
588 }
589 else {
590 if (!match(L2, m_And(m_Value(L11), m_Value(L12))))
591 return 0;
592 std::swap(L1, L2);
593 L21 = L22 = 0;
594 }
595
596 Value *R1 = RHS->getOperand(0);
597 Value *R2 = RHS->getOperand(1);
598 Value *R11,*R12;
599 bool ok = false;
600 if (match(R1, m_And(m_Value(R11), m_Value(R12)))) {
601 if (R11 != 0 && (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22)) {
602 A = R11; D = R12; E = R2; ok = true;
603 }
604 else
605 if (R12 != 0 && (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22)) {
606 A = R12; D = R11; E = R2; ok = true;
607 }
608 }
609 if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) {
610 if (R11 != 0 && (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22)) {
611 A = R11; D = R12; E = R1; ok = true;
612 }
613 else
614 if (R12 != 0 && (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22)) {
615 A = R12; D = R11; E = R1; ok = true;
616 }
617 else
618 return 0;
619 }
620 if (!ok)
621 return 0;
622
623 if (L11 == A) {
624 B = L12; C = L2;
625 }
626 else if (L12 == A) {
627 B = L11; C = L2;
628 }
629 else if (L21 == A) {
630 B = L22; C = L1;
631 }
632 else if (L22 == A) {
633 B = L21; C = L1;
634 }
635
636 unsigned left_type = getTypeOfMaskedICmp(A, B, C, LHSCC);
637 unsigned right_type = getTypeOfMaskedICmp(A, D, E, RHSCC);
638 return left_type & right_type;
639 }
640 /// foldLogOpOfMaskedICmps:
641 /// try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
642 /// into a single (icmp(A & X) ==/!= Y)
foldLogOpOfMaskedICmps(ICmpInst * LHS,ICmpInst * RHS,ICmpInst::Predicate NEWCC,llvm::InstCombiner::BuilderTy * Builder)643 static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
644 ICmpInst::Predicate NEWCC,
645 llvm::InstCombiner::BuilderTy* Builder) {
646 Value *A = 0, *B = 0, *C = 0, *D = 0, *E = 0;
647 unsigned mask = foldLogOpOfMaskedICmpsHelper(A, B, C, D, E, LHS, RHS);
648 if (mask == 0) return 0;
649
650 if (NEWCC == ICmpInst::ICMP_NE)
651 mask >>= 1; // treat "Not"-states as normal states
652
653 if (mask & FoldMskICmp_Mask_AllZeroes) {
654 // (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
655 // -> (icmp eq (A & (B|D)), 0)
656 Value* newOr = Builder->CreateOr(B, D);
657 Value* newAnd = Builder->CreateAnd(A, newOr);
658 // we can't use C as zero, because we might actually handle
659 // (icmp ne (A & B), B) & (icmp ne (A & D), D)
660 // with B and D, having a single bit set
661 Value* zero = Constant::getNullValue(A->getType());
662 return Builder->CreateICmp(NEWCC, newAnd, zero);
663 }
664 else if (mask & FoldMskICmp_BMask_AllOnes) {
665 // (icmp eq (A & B), B) & (icmp eq (A & D), D)
666 // -> (icmp eq (A & (B|D)), (B|D))
667 Value* newOr = Builder->CreateOr(B, D);
668 Value* newAnd = Builder->CreateAnd(A, newOr);
669 return Builder->CreateICmp(NEWCC, newAnd, newOr);
670 }
671 else if (mask & FoldMskICmp_AMask_AllOnes) {
672 // (icmp eq (A & B), A) & (icmp eq (A & D), A)
673 // -> (icmp eq (A & (B&D)), A)
674 Value* newAnd1 = Builder->CreateAnd(B, D);
675 Value* newAnd = Builder->CreateAnd(A, newAnd1);
676 return Builder->CreateICmp(NEWCC, newAnd, A);
677 }
678 else if (mask & FoldMskICmp_BMask_Mixed) {
679 // (icmp eq (A & B), C) & (icmp eq (A & D), E)
680 // We already know that B & C == C && D & E == E.
681 // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
682 // C and E, which are shared by both the mask B and the mask D, don't
683 // contradict, then we can transform to
684 // -> (icmp eq (A & (B|D)), (C|E))
685 // Currently, we only handle the case of B, C, D, and E being constant.
686 ConstantInt *BCst = dyn_cast<ConstantInt>(B);
687 if (BCst == 0) return 0;
688 ConstantInt *DCst = dyn_cast<ConstantInt>(D);
689 if (DCst == 0) return 0;
690 // we can't simply use C and E, because we might actually handle
691 // (icmp ne (A & B), B) & (icmp eq (A & D), D)
692 // with B and D, having a single bit set
693
694 ConstantInt *CCst = dyn_cast<ConstantInt>(C);
695 if (CCst == 0) return 0;
696 if (LHS->getPredicate() != NEWCC)
697 CCst = dyn_cast<ConstantInt>( ConstantExpr::getXor(BCst, CCst) );
698 ConstantInt *ECst = dyn_cast<ConstantInt>(E);
699 if (ECst == 0) return 0;
700 if (RHS->getPredicate() != NEWCC)
701 ECst = dyn_cast<ConstantInt>( ConstantExpr::getXor(DCst, ECst) );
702 ConstantInt* MCst = dyn_cast<ConstantInt>(
703 ConstantExpr::getAnd(ConstantExpr::getAnd(BCst, DCst),
704 ConstantExpr::getXor(CCst, ECst)) );
705 // if there is a conflict we should actually return a false for the
706 // whole construct
707 if (!MCst->isZero())
708 return 0;
709 Value *newOr1 = Builder->CreateOr(B, D);
710 Value *newOr2 = ConstantExpr::getOr(CCst, ECst);
711 Value *newAnd = Builder->CreateAnd(A, newOr1);
712 return Builder->CreateICmp(NEWCC, newAnd, newOr2);
713 }
714 return 0;
715 }
716
717 /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
FoldAndOfICmps(ICmpInst * LHS,ICmpInst * RHS)718 Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
719 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
720
721 // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
722 if (PredicatesFoldable(LHSCC, RHSCC)) {
723 if (LHS->getOperand(0) == RHS->getOperand(1) &&
724 LHS->getOperand(1) == RHS->getOperand(0))
725 LHS->swapOperands();
726 if (LHS->getOperand(0) == RHS->getOperand(0) &&
727 LHS->getOperand(1) == RHS->getOperand(1)) {
728 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
729 unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
730 bool isSigned = LHS->isSigned() || RHS->isSigned();
731 return getICmpValue(isSigned, Code, Op0, Op1, Builder);
732 }
733 }
734
735 // handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E)
736 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_EQ, Builder))
737 return V;
738
739 // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
740 Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
741 ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
742 ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
743 if (LHSCst == 0 || RHSCst == 0) return 0;
744
745 if (LHSCst == RHSCst && LHSCC == RHSCC) {
746 // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
747 // where C is a power of 2
748 if (LHSCC == ICmpInst::ICMP_ULT &&
749 LHSCst->getValue().isPowerOf2()) {
750 Value *NewOr = Builder->CreateOr(Val, Val2);
751 return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
752 }
753
754 // (icmp eq A, 0) & (icmp eq B, 0) --> (icmp eq (A|B), 0)
755 if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
756 Value *NewOr = Builder->CreateOr(Val, Val2);
757 return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
758 }
759
760 // (icmp slt A, 0) & (icmp slt B, 0) --> (icmp slt (A&B), 0)
761 if (LHSCC == ICmpInst::ICMP_SLT && LHSCst->isZero()) {
762 Value *NewAnd = Builder->CreateAnd(Val, Val2);
763 return Builder->CreateICmp(LHSCC, NewAnd, LHSCst);
764 }
765
766 // (icmp sgt A, -1) & (icmp sgt B, -1) --> (icmp sgt (A|B), -1)
767 if (LHSCC == ICmpInst::ICMP_SGT && LHSCst->isAllOnesValue()) {
768 Value *NewOr = Builder->CreateOr(Val, Val2);
769 return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
770 }
771 }
772
773 // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
774 // where CMAX is the all ones value for the truncated type,
775 // iff the lower bits of C2 and CA are zero.
776 if (LHSCC == RHSCC && ICmpInst::isEquality(LHSCC) &&
777 LHS->hasOneUse() && RHS->hasOneUse()) {
778 Value *V;
779 ConstantInt *AndCst, *SmallCst = 0, *BigCst = 0;
780
781 // (trunc x) == C1 & (and x, CA) == C2
782 if (match(Val2, m_Trunc(m_Value(V))) &&
783 match(Val, m_And(m_Specific(V), m_ConstantInt(AndCst)))) {
784 SmallCst = RHSCst;
785 BigCst = LHSCst;
786 }
787 // (and x, CA) == C2 & (trunc x) == C1
788 else if (match(Val, m_Trunc(m_Value(V))) &&
789 match(Val2, m_And(m_Specific(V), m_ConstantInt(AndCst)))) {
790 SmallCst = LHSCst;
791 BigCst = RHSCst;
792 }
793
794 if (SmallCst && BigCst) {
795 unsigned BigBitSize = BigCst->getType()->getBitWidth();
796 unsigned SmallBitSize = SmallCst->getType()->getBitWidth();
797
798 // Check that the low bits are zero.
799 APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
800 if ((Low & AndCst->getValue()) == 0 && (Low & BigCst->getValue()) == 0) {
801 Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue());
802 APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue();
803 Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N);
804 return Builder->CreateICmp(LHSCC, NewAnd, NewVal);
805 }
806 }
807 }
808
809 // From here on, we only handle:
810 // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
811 if (Val != Val2) return 0;
812
813 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
814 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
815 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
816 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
817 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
818 return 0;
819
820 // Make a constant range that's the intersection of the two icmp ranges.
821 // If the intersection is empty, we know that the result is false.
822 ConstantRange LHSRange =
823 ConstantRange::makeICmpRegion(LHSCC, LHSCst->getValue());
824 ConstantRange RHSRange =
825 ConstantRange::makeICmpRegion(RHSCC, RHSCst->getValue());
826
827 if (LHSRange.intersectWith(RHSRange).isEmptySet())
828 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
829
830 // We can't fold (ugt x, C) & (sgt x, C2).
831 if (!PredicatesFoldable(LHSCC, RHSCC))
832 return 0;
833
834 // Ensure that the larger constant is on the RHS.
835 bool ShouldSwap;
836 if (CmpInst::isSigned(LHSCC) ||
837 (ICmpInst::isEquality(LHSCC) &&
838 CmpInst::isSigned(RHSCC)))
839 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
840 else
841 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
842
843 if (ShouldSwap) {
844 std::swap(LHS, RHS);
845 std::swap(LHSCst, RHSCst);
846 std::swap(LHSCC, RHSCC);
847 }
848
849 // At this point, we know we have two icmp instructions
850 // comparing a value against two constants and and'ing the result
851 // together. Because of the above check, we know that we only have
852 // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
853 // (from the icmp folding check above), that the two constants
854 // are not equal and that the larger constant is on the RHS
855 assert(LHSCst != RHSCst && "Compares not folded above?");
856
857 switch (LHSCC) {
858 default: llvm_unreachable("Unknown integer condition code!");
859 case ICmpInst::ICMP_EQ:
860 switch (RHSCC) {
861 default: llvm_unreachable("Unknown integer condition code!");
862 case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
863 case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
864 case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
865 return LHS;
866 }
867 case ICmpInst::ICMP_NE:
868 switch (RHSCC) {
869 default: llvm_unreachable("Unknown integer condition code!");
870 case ICmpInst::ICMP_ULT:
871 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
872 return Builder->CreateICmpULT(Val, LHSCst);
873 break; // (X != 13 & X u< 15) -> no change
874 case ICmpInst::ICMP_SLT:
875 if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
876 return Builder->CreateICmpSLT(Val, LHSCst);
877 break; // (X != 13 & X s< 15) -> no change
878 case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
879 case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
880 case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
881 return RHS;
882 case ICmpInst::ICMP_NE:
883 if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
884 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
885 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
886 return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1));
887 }
888 break; // (X != 13 & X != 15) -> no change
889 }
890 break;
891 case ICmpInst::ICMP_ULT:
892 switch (RHSCC) {
893 default: llvm_unreachable("Unknown integer condition code!");
894 case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
895 case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
896 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
897 case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
898 break;
899 case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
900 case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
901 return LHS;
902 case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
903 break;
904 }
905 break;
906 case ICmpInst::ICMP_SLT:
907 switch (RHSCC) {
908 default: llvm_unreachable("Unknown integer condition code!");
909 case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
910 break;
911 case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
912 case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
913 return LHS;
914 case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
915 break;
916 }
917 break;
918 case ICmpInst::ICMP_UGT:
919 switch (RHSCC) {
920 default: llvm_unreachable("Unknown integer condition code!");
921 case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
922 case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
923 return RHS;
924 case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
925 break;
926 case ICmpInst::ICMP_NE:
927 if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
928 return Builder->CreateICmp(LHSCC, Val, RHSCst);
929 break; // (X u> 13 & X != 15) -> no change
930 case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
931 return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true);
932 case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
933 break;
934 }
935 break;
936 case ICmpInst::ICMP_SGT:
937 switch (RHSCC) {
938 default: llvm_unreachable("Unknown integer condition code!");
939 case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
940 case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
941 return RHS;
942 case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
943 break;
944 case ICmpInst::ICMP_NE:
945 if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
946 return Builder->CreateICmp(LHSCC, Val, RHSCst);
947 break; // (X s> 13 & X != 15) -> no change
948 case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
949 return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true);
950 case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
951 break;
952 }
953 break;
954 }
955
956 return 0;
957 }
958
959 /// FoldAndOfFCmps - Optimize (fcmp)&(fcmp). NOTE: Unlike the rest of
960 /// instcombine, this returns a Value which should already be inserted into the
961 /// function.
FoldAndOfFCmps(FCmpInst * LHS,FCmpInst * RHS)962 Value *InstCombiner::FoldAndOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
963 if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
964 RHS->getPredicate() == FCmpInst::FCMP_ORD) {
965 // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
966 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
967 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
968 // If either of the constants are nans, then the whole thing returns
969 // false.
970 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
971 return ConstantInt::getFalse(LHS->getContext());
972 return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
973 }
974
975 // Handle vector zeros. This occurs because the canonical form of
976 // "fcmp ord x,x" is "fcmp ord x, 0".
977 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
978 isa<ConstantAggregateZero>(RHS->getOperand(1)))
979 return Builder->CreateFCmpORD(LHS->getOperand(0), RHS->getOperand(0));
980 return 0;
981 }
982
983 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
984 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
985 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
986
987
988 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
989 // Swap RHS operands to match LHS.
990 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
991 std::swap(Op1LHS, Op1RHS);
992 }
993
994 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
995 // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
996 if (Op0CC == Op1CC)
997 return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
998 if (Op0CC == FCmpInst::FCMP_FALSE || Op1CC == FCmpInst::FCMP_FALSE)
999 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
1000 if (Op0CC == FCmpInst::FCMP_TRUE)
1001 return RHS;
1002 if (Op1CC == FCmpInst::FCMP_TRUE)
1003 return LHS;
1004
1005 bool Op0Ordered;
1006 bool Op1Ordered;
1007 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
1008 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
1009 if (Op1Pred == 0) {
1010 std::swap(LHS, RHS);
1011 std::swap(Op0Pred, Op1Pred);
1012 std::swap(Op0Ordered, Op1Ordered);
1013 }
1014 if (Op0Pred == 0) {
1015 // uno && ueq -> uno && (uno || eq) -> ueq
1016 // ord && olt -> ord && (ord && lt) -> olt
1017 if (Op0Ordered == Op1Ordered)
1018 return RHS;
1019
1020 // uno && oeq -> uno && (ord && eq) -> false
1021 // uno && ord -> false
1022 if (!Op0Ordered)
1023 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
1024 // ord && ueq -> ord && (uno || eq) -> oeq
1025 return getFCmpValue(true, Op1Pred, Op0LHS, Op0RHS, Builder);
1026 }
1027 }
1028
1029 return 0;
1030 }
1031
1032
visitAnd(BinaryOperator & I)1033 Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
1034 bool Changed = SimplifyAssociativeOrCommutative(I);
1035 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1036
1037 if (Value *V = SimplifyAndInst(Op0, Op1, TD))
1038 return ReplaceInstUsesWith(I, V);
1039
1040 // (A|B)&(A|C) -> A|(B&C) etc
1041 if (Value *V = SimplifyUsingDistributiveLaws(I))
1042 return ReplaceInstUsesWith(I, V);
1043
1044 // See if we can simplify any instructions used by the instruction whose sole
1045 // purpose is to compute bits we don't care about.
1046 if (SimplifyDemandedInstructionBits(I))
1047 return &I;
1048
1049 if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
1050 const APInt &AndRHSMask = AndRHS->getValue();
1051
1052 // Optimize a variety of ((val OP C1) & C2) combinations...
1053 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
1054 Value *Op0LHS = Op0I->getOperand(0);
1055 Value *Op0RHS = Op0I->getOperand(1);
1056 switch (Op0I->getOpcode()) {
1057 default: break;
1058 case Instruction::Xor:
1059 case Instruction::Or: {
1060 // If the mask is only needed on one incoming arm, push it up.
1061 if (!Op0I->hasOneUse()) break;
1062
1063 APInt NotAndRHS(~AndRHSMask);
1064 if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
1065 // Not masking anything out for the LHS, move to RHS.
1066 Value *NewRHS = Builder->CreateAnd(Op0RHS, AndRHS,
1067 Op0RHS->getName()+".masked");
1068 return BinaryOperator::Create(Op0I->getOpcode(), Op0LHS, NewRHS);
1069 }
1070 if (!isa<Constant>(Op0RHS) &&
1071 MaskedValueIsZero(Op0RHS, NotAndRHS)) {
1072 // Not masking anything out for the RHS, move to LHS.
1073 Value *NewLHS = Builder->CreateAnd(Op0LHS, AndRHS,
1074 Op0LHS->getName()+".masked");
1075 return BinaryOperator::Create(Op0I->getOpcode(), NewLHS, Op0RHS);
1076 }
1077
1078 break;
1079 }
1080 case Instruction::Add:
1081 // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
1082 // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1083 // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
1084 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
1085 return BinaryOperator::CreateAnd(V, AndRHS);
1086 if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
1087 return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
1088 break;
1089
1090 case Instruction::Sub:
1091 // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
1092 // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1093 // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
1094 if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
1095 return BinaryOperator::CreateAnd(V, AndRHS);
1096
1097 // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
1098 // has 1's for all bits that the subtraction with A might affect.
1099 if (Op0I->hasOneUse() && !match(Op0LHS, m_Zero())) {
1100 uint32_t BitWidth = AndRHSMask.getBitWidth();
1101 uint32_t Zeros = AndRHSMask.countLeadingZeros();
1102 APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
1103
1104 if (MaskedValueIsZero(Op0LHS, Mask)) {
1105 Value *NewNeg = Builder->CreateNeg(Op0RHS);
1106 return BinaryOperator::CreateAnd(NewNeg, AndRHS);
1107 }
1108 }
1109 break;
1110
1111 case Instruction::Shl:
1112 case Instruction::LShr:
1113 // (1 << x) & 1 --> zext(x == 0)
1114 // (1 >> x) & 1 --> zext(x == 0)
1115 if (AndRHSMask == 1 && Op0LHS == AndRHS) {
1116 Value *NewICmp =
1117 Builder->CreateICmpEQ(Op0RHS, Constant::getNullValue(I.getType()));
1118 return new ZExtInst(NewICmp, I.getType());
1119 }
1120 break;
1121 }
1122
1123 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
1124 if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
1125 return Res;
1126 }
1127
1128 // If this is an integer truncation, and if the source is an 'and' with
1129 // immediate, transform it. This frequently occurs for bitfield accesses.
1130 {
1131 Value *X = 0; ConstantInt *YC = 0;
1132 if (match(Op0, m_Trunc(m_And(m_Value(X), m_ConstantInt(YC))))) {
1133 // Change: and (trunc (and X, YC) to T), C2
1134 // into : and (trunc X to T), trunc(YC) & C2
1135 // This will fold the two constants together, which may allow
1136 // other simplifications.
1137 Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk");
1138 Constant *C3 = ConstantExpr::getTrunc(YC, I.getType());
1139 C3 = ConstantExpr::getAnd(C3, AndRHS);
1140 return BinaryOperator::CreateAnd(NewCast, C3);
1141 }
1142 }
1143
1144 // Try to fold constant and into select arguments.
1145 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1146 if (Instruction *R = FoldOpIntoSelect(I, SI))
1147 return R;
1148 if (isa<PHINode>(Op0))
1149 if (Instruction *NV = FoldOpIntoPhi(I))
1150 return NV;
1151 }
1152
1153
1154 // (~A & ~B) == (~(A | B)) - De Morgan's Law
1155 if (Value *Op0NotVal = dyn_castNotVal(Op0))
1156 if (Value *Op1NotVal = dyn_castNotVal(Op1))
1157 if (Op0->hasOneUse() && Op1->hasOneUse()) {
1158 Value *Or = Builder->CreateOr(Op0NotVal, Op1NotVal,
1159 I.getName()+".demorgan");
1160 return BinaryOperator::CreateNot(Or);
1161 }
1162
1163 {
1164 Value *A = 0, *B = 0, *C = 0, *D = 0;
1165 // (A|B) & ~(A&B) -> A^B
1166 if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
1167 match(Op1, m_Not(m_And(m_Value(C), m_Value(D)))) &&
1168 ((A == C && B == D) || (A == D && B == C)))
1169 return BinaryOperator::CreateXor(A, B);
1170
1171 // ~(A&B) & (A|B) -> A^B
1172 if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
1173 match(Op0, m_Not(m_And(m_Value(C), m_Value(D)))) &&
1174 ((A == C && B == D) || (A == D && B == C)))
1175 return BinaryOperator::CreateXor(A, B);
1176
1177 // A&(A^B) => A & ~B
1178 {
1179 Value *tmpOp0 = Op0;
1180 Value *tmpOp1 = Op1;
1181 if (Op0->hasOneUse() &&
1182 match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
1183 if (A == Op1 || B == Op1 ) {
1184 tmpOp1 = Op0;
1185 tmpOp0 = Op1;
1186 // Simplify below
1187 }
1188 }
1189
1190 if (tmpOp1->hasOneUse() &&
1191 match(tmpOp1, m_Xor(m_Value(A), m_Value(B)))) {
1192 if (B == tmpOp0) {
1193 std::swap(A, B);
1194 }
1195 // Notice that the patten (A&(~B)) is actually (A&(-1^B)), so if
1196 // A is originally -1 (or a vector of -1 and undefs), then we enter
1197 // an endless loop. By checking that A is non-constant we ensure that
1198 // we will never get to the loop.
1199 if (A == tmpOp0 && !isa<Constant>(A)) // A&(A^B) -> A & ~B
1200 return BinaryOperator::CreateAnd(A, Builder->CreateNot(B));
1201 }
1202 }
1203
1204 // (A&((~A)|B)) -> A&B
1205 if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
1206 match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
1207 return BinaryOperator::CreateAnd(A, Op1);
1208 if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
1209 match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
1210 return BinaryOperator::CreateAnd(A, Op0);
1211 }
1212
1213 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1))
1214 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
1215 if (Value *Res = FoldAndOfICmps(LHS, RHS))
1216 return ReplaceInstUsesWith(I, Res);
1217
1218 // If and'ing two fcmp, try combine them into one.
1219 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
1220 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
1221 if (Value *Res = FoldAndOfFCmps(LHS, RHS))
1222 return ReplaceInstUsesWith(I, Res);
1223
1224
1225 // fold (and (cast A), (cast B)) -> (cast (and A, B))
1226 if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
1227 if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) {
1228 Type *SrcTy = Op0C->getOperand(0)->getType();
1229 if (Op0C->getOpcode() == Op1C->getOpcode() && // same cast kind ?
1230 SrcTy == Op1C->getOperand(0)->getType() &&
1231 SrcTy->isIntOrIntVectorTy()) {
1232 Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0);
1233
1234 // Only do this if the casts both really cause code to be generated.
1235 if (ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
1236 ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
1237 Value *NewOp = Builder->CreateAnd(Op0COp, Op1COp, I.getName());
1238 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
1239 }
1240
1241 // If this is and(cast(icmp), cast(icmp)), try to fold this even if the
1242 // cast is otherwise not optimizable. This happens for vector sexts.
1243 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
1244 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
1245 if (Value *Res = FoldAndOfICmps(LHS, RHS))
1246 return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
1247
1248 // If this is and(cast(fcmp), cast(fcmp)), try to fold this even if the
1249 // cast is otherwise not optimizable. This happens for vector sexts.
1250 if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
1251 if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
1252 if (Value *Res = FoldAndOfFCmps(LHS, RHS))
1253 return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
1254 }
1255 }
1256
1257 // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
1258 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
1259 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
1260 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
1261 SI0->getOperand(1) == SI1->getOperand(1) &&
1262 (SI0->hasOneUse() || SI1->hasOneUse())) {
1263 Value *NewOp =
1264 Builder->CreateAnd(SI0->getOperand(0), SI1->getOperand(0),
1265 SI0->getName());
1266 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
1267 SI1->getOperand(1));
1268 }
1269 }
1270
1271 return Changed ? &I : 0;
1272 }
1273
1274 /// CollectBSwapParts - Analyze the specified subexpression and see if it is
1275 /// capable of providing pieces of a bswap. The subexpression provides pieces
1276 /// of a bswap if it is proven that each of the non-zero bytes in the output of
1277 /// the expression came from the corresponding "byte swapped" byte in some other
1278 /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
1279 /// we know that the expression deposits the low byte of %X into the high byte
1280 /// of the bswap result and that all other bytes are zero. This expression is
1281 /// accepted, the high byte of ByteValues is set to X to indicate a correct
1282 /// match.
1283 ///
1284 /// This function returns true if the match was unsuccessful and false if so.
1285 /// On entry to the function the "OverallLeftShift" is a signed integer value
1286 /// indicating the number of bytes that the subexpression is later shifted. For
1287 /// example, if the expression is later right shifted by 16 bits, the
1288 /// OverallLeftShift value would be -2 on entry. This is used to specify which
1289 /// byte of ByteValues is actually being set.
1290 ///
1291 /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
1292 /// byte is masked to zero by a user. For example, in (X & 255), X will be
1293 /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
1294 /// this function to working on up to 32-byte (256 bit) values. ByteMask is
1295 /// always in the local (OverallLeftShift) coordinate space.
1296 ///
CollectBSwapParts(Value * V,int OverallLeftShift,uint32_t ByteMask,SmallVector<Value *,8> & ByteValues)1297 static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
1298 SmallVector<Value*, 8> &ByteValues) {
1299 if (Instruction *I = dyn_cast<Instruction>(V)) {
1300 // If this is an or instruction, it may be an inner node of the bswap.
1301 if (I->getOpcode() == Instruction::Or) {
1302 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1303 ByteValues) ||
1304 CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
1305 ByteValues);
1306 }
1307
1308 // If this is a logical shift by a constant multiple of 8, recurse with
1309 // OverallLeftShift and ByteMask adjusted.
1310 if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
1311 unsigned ShAmt =
1312 cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
1313 // Ensure the shift amount is defined and of a byte value.
1314 if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
1315 return true;
1316
1317 unsigned ByteShift = ShAmt >> 3;
1318 if (I->getOpcode() == Instruction::Shl) {
1319 // X << 2 -> collect(X, +2)
1320 OverallLeftShift += ByteShift;
1321 ByteMask >>= ByteShift;
1322 } else {
1323 // X >>u 2 -> collect(X, -2)
1324 OverallLeftShift -= ByteShift;
1325 ByteMask <<= ByteShift;
1326 ByteMask &= (~0U >> (32-ByteValues.size()));
1327 }
1328
1329 if (OverallLeftShift >= (int)ByteValues.size()) return true;
1330 if (OverallLeftShift <= -(int)ByteValues.size()) return true;
1331
1332 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1333 ByteValues);
1334 }
1335
1336 // If this is a logical 'and' with a mask that clears bytes, clear the
1337 // corresponding bytes in ByteMask.
1338 if (I->getOpcode() == Instruction::And &&
1339 isa<ConstantInt>(I->getOperand(1))) {
1340 // Scan every byte of the and mask, seeing if the byte is either 0 or 255.
1341 unsigned NumBytes = ByteValues.size();
1342 APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
1343 const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
1344
1345 for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
1346 // If this byte is masked out by a later operation, we don't care what
1347 // the and mask is.
1348 if ((ByteMask & (1 << i)) == 0)
1349 continue;
1350
1351 // If the AndMask is all zeros for this byte, clear the bit.
1352 APInt MaskB = AndMask & Byte;
1353 if (MaskB == 0) {
1354 ByteMask &= ~(1U << i);
1355 continue;
1356 }
1357
1358 // If the AndMask is not all ones for this byte, it's not a bytezap.
1359 if (MaskB != Byte)
1360 return true;
1361
1362 // Otherwise, this byte is kept.
1363 }
1364
1365 return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
1366 ByteValues);
1367 }
1368 }
1369
1370 // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
1371 // the input value to the bswap. Some observations: 1) if more than one byte
1372 // is demanded from this input, then it could not be successfully assembled
1373 // into a byteswap. At least one of the two bytes would not be aligned with
1374 // their ultimate destination.
1375 if (!isPowerOf2_32(ByteMask)) return true;
1376 unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
1377
1378 // 2) The input and ultimate destinations must line up: if byte 3 of an i32
1379 // is demanded, it needs to go into byte 0 of the result. This means that the
1380 // byte needs to be shifted until it lands in the right byte bucket. The
1381 // shift amount depends on the position: if the byte is coming from the high
1382 // part of the value (e.g. byte 3) then it must be shifted right. If from the
1383 // low part, it must be shifted left.
1384 unsigned DestByteNo = InputByteNo + OverallLeftShift;
1385 if (InputByteNo < ByteValues.size()/2) {
1386 if (ByteValues.size()-1-DestByteNo != InputByteNo)
1387 return true;
1388 } else {
1389 if (ByteValues.size()-1-DestByteNo != InputByteNo)
1390 return true;
1391 }
1392
1393 // If the destination byte value is already defined, the values are or'd
1394 // together, which isn't a bswap (unless it's an or of the same bits).
1395 if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
1396 return true;
1397 ByteValues[DestByteNo] = V;
1398 return false;
1399 }
1400
1401 /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
1402 /// If so, insert the new bswap intrinsic and return it.
MatchBSwap(BinaryOperator & I)1403 Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
1404 IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
1405 if (!ITy || ITy->getBitWidth() % 16 ||
1406 // ByteMask only allows up to 32-byte values.
1407 ITy->getBitWidth() > 32*8)
1408 return 0; // Can only bswap pairs of bytes. Can't do vectors.
1409
1410 /// ByteValues - For each byte of the result, we keep track of which value
1411 /// defines each byte.
1412 SmallVector<Value*, 8> ByteValues;
1413 ByteValues.resize(ITy->getBitWidth()/8);
1414
1415 // Try to find all the pieces corresponding to the bswap.
1416 uint32_t ByteMask = ~0U >> (32-ByteValues.size());
1417 if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
1418 return 0;
1419
1420 // Check to see if all of the bytes come from the same value.
1421 Value *V = ByteValues[0];
1422 if (V == 0) return 0; // Didn't find a byte? Must be zero.
1423
1424 // Check to make sure that all of the bytes come from the same value.
1425 for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
1426 if (ByteValues[i] != V)
1427 return 0;
1428 Module *M = I.getParent()->getParent()->getParent();
1429 Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, ITy);
1430 return CallInst::Create(F, V);
1431 }
1432
1433 /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
1434 /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
1435 /// we can simplify this expression to "cond ? C : D or B".
MatchSelectFromAndOr(Value * A,Value * B,Value * C,Value * D)1436 static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
1437 Value *C, Value *D) {
1438 // If A is not a select of -1/0, this cannot match.
1439 Value *Cond = 0;
1440 if (!match(A, m_SExt(m_Value(Cond))) ||
1441 !Cond->getType()->isIntegerTy(1))
1442 return 0;
1443
1444 // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
1445 if (match(D, m_Not(m_SExt(m_Specific(Cond)))))
1446 return SelectInst::Create(Cond, C, B);
1447 if (match(D, m_SExt(m_Not(m_Specific(Cond)))))
1448 return SelectInst::Create(Cond, C, B);
1449
1450 // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
1451 if (match(B, m_Not(m_SExt(m_Specific(Cond)))))
1452 return SelectInst::Create(Cond, C, D);
1453 if (match(B, m_SExt(m_Not(m_Specific(Cond)))))
1454 return SelectInst::Create(Cond, C, D);
1455 return 0;
1456 }
1457
1458 /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
FoldOrOfICmps(ICmpInst * LHS,ICmpInst * RHS)1459 Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
1460 ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
1461
1462 // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
1463 if (PredicatesFoldable(LHSCC, RHSCC)) {
1464 if (LHS->getOperand(0) == RHS->getOperand(1) &&
1465 LHS->getOperand(1) == RHS->getOperand(0))
1466 LHS->swapOperands();
1467 if (LHS->getOperand(0) == RHS->getOperand(0) &&
1468 LHS->getOperand(1) == RHS->getOperand(1)) {
1469 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
1470 unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
1471 bool isSigned = LHS->isSigned() || RHS->isSigned();
1472 return getICmpValue(isSigned, Code, Op0, Op1, Builder);
1473 }
1474 }
1475
1476 // handle (roughly):
1477 // (icmp ne (A & B), C) | (icmp ne (A & D), E)
1478 if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_NE, Builder))
1479 return V;
1480
1481 // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
1482 Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
1483 ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
1484 ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
1485 if (LHSCst == 0 || RHSCst == 0) return 0;
1486
1487 if (LHSCst == RHSCst && LHSCC == RHSCC) {
1488 // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
1489 if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
1490 Value *NewOr = Builder->CreateOr(Val, Val2);
1491 return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
1492 }
1493
1494 // (icmp slt A, 0) | (icmp slt B, 0) --> (icmp slt (A|B), 0)
1495 if (LHSCC == ICmpInst::ICMP_SLT && LHSCst->isZero()) {
1496 Value *NewOr = Builder->CreateOr(Val, Val2);
1497 return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
1498 }
1499
1500 // (icmp sgt A, -1) | (icmp sgt B, -1) --> (icmp sgt (A&B), -1)
1501 if (LHSCC == ICmpInst::ICMP_SGT && LHSCst->isAllOnesValue()) {
1502 Value *NewAnd = Builder->CreateAnd(Val, Val2);
1503 return Builder->CreateICmp(LHSCC, NewAnd, LHSCst);
1504 }
1505 }
1506
1507 // (icmp ult (X + CA), C1) | (icmp eq X, C2) -> (icmp ule (X + CA), C1)
1508 // iff C2 + CA == C1.
1509 if (LHSCC == ICmpInst::ICMP_ULT && RHSCC == ICmpInst::ICMP_EQ) {
1510 ConstantInt *AddCst;
1511 if (match(Val, m_Add(m_Specific(Val2), m_ConstantInt(AddCst))))
1512 if (RHSCst->getValue() + AddCst->getValue() == LHSCst->getValue())
1513 return Builder->CreateICmpULE(Val, LHSCst);
1514 }
1515
1516 // From here on, we only handle:
1517 // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
1518 if (Val != Val2) return 0;
1519
1520 // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
1521 if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
1522 RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
1523 LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
1524 RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
1525 return 0;
1526
1527 // We can't fold (ugt x, C) | (sgt x, C2).
1528 if (!PredicatesFoldable(LHSCC, RHSCC))
1529 return 0;
1530
1531 // Ensure that the larger constant is on the RHS.
1532 bool ShouldSwap;
1533 if (CmpInst::isSigned(LHSCC) ||
1534 (ICmpInst::isEquality(LHSCC) &&
1535 CmpInst::isSigned(RHSCC)))
1536 ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
1537 else
1538 ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
1539
1540 if (ShouldSwap) {
1541 std::swap(LHS, RHS);
1542 std::swap(LHSCst, RHSCst);
1543 std::swap(LHSCC, RHSCC);
1544 }
1545
1546 // At this point, we know we have two icmp instructions
1547 // comparing a value against two constants and or'ing the result
1548 // together. Because of the above check, we know that we only have
1549 // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
1550 // icmp folding check above), that the two constants are not
1551 // equal.
1552 assert(LHSCst != RHSCst && "Compares not folded above?");
1553
1554 switch (LHSCC) {
1555 default: llvm_unreachable("Unknown integer condition code!");
1556 case ICmpInst::ICMP_EQ:
1557 switch (RHSCC) {
1558 default: llvm_unreachable("Unknown integer condition code!");
1559 case ICmpInst::ICMP_EQ:
1560 if (LHSCst == SubOne(RHSCst)) {
1561 // (X == 13 | X == 14) -> X-13 <u 2
1562 Constant *AddCST = ConstantExpr::getNeg(LHSCst);
1563 Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
1564 AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
1565 return Builder->CreateICmpULT(Add, AddCST);
1566 }
1567 break; // (X == 13 | X == 15) -> no change
1568 case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
1569 case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
1570 break;
1571 case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
1572 case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
1573 case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
1574 return RHS;
1575 }
1576 break;
1577 case ICmpInst::ICMP_NE:
1578 switch (RHSCC) {
1579 default: llvm_unreachable("Unknown integer condition code!");
1580 case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
1581 case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
1582 case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
1583 return LHS;
1584 case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
1585 case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
1586 case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
1587 return ConstantInt::getTrue(LHS->getContext());
1588 }
1589 break;
1590 case ICmpInst::ICMP_ULT:
1591 switch (RHSCC) {
1592 default: llvm_unreachable("Unknown integer condition code!");
1593 case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
1594 break;
1595 case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
1596 // If RHSCst is [us]MAXINT, it is always false. Not handling
1597 // this can cause overflow.
1598 if (RHSCst->isMaxValue(false))
1599 return LHS;
1600 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false);
1601 case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
1602 break;
1603 case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
1604 case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
1605 return RHS;
1606 case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
1607 break;
1608 }
1609 break;
1610 case ICmpInst::ICMP_SLT:
1611 switch (RHSCC) {
1612 default: llvm_unreachable("Unknown integer condition code!");
1613 case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
1614 break;
1615 case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
1616 // If RHSCst is [us]MAXINT, it is always false. Not handling
1617 // this can cause overflow.
1618 if (RHSCst->isMaxValue(true))
1619 return LHS;
1620 return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false);
1621 case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
1622 break;
1623 case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
1624 case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
1625 return RHS;
1626 case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
1627 break;
1628 }
1629 break;
1630 case ICmpInst::ICMP_UGT:
1631 switch (RHSCC) {
1632 default: llvm_unreachable("Unknown integer condition code!");
1633 case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
1634 case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
1635 return LHS;
1636 case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
1637 break;
1638 case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
1639 case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
1640 return ConstantInt::getTrue(LHS->getContext());
1641 case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
1642 break;
1643 }
1644 break;
1645 case ICmpInst::ICMP_SGT:
1646 switch (RHSCC) {
1647 default: llvm_unreachable("Unknown integer condition code!");
1648 case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
1649 case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
1650 return LHS;
1651 case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
1652 break;
1653 case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
1654 case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
1655 return ConstantInt::getTrue(LHS->getContext());
1656 case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
1657 break;
1658 }
1659 break;
1660 }
1661 return 0;
1662 }
1663
1664 /// FoldOrOfFCmps - Optimize (fcmp)|(fcmp). NOTE: Unlike the rest of
1665 /// instcombine, this returns a Value which should already be inserted into the
1666 /// function.
FoldOrOfFCmps(FCmpInst * LHS,FCmpInst * RHS)1667 Value *InstCombiner::FoldOrOfFCmps(FCmpInst *LHS, FCmpInst *RHS) {
1668 if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
1669 RHS->getPredicate() == FCmpInst::FCMP_UNO &&
1670 LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
1671 if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
1672 if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
1673 // If either of the constants are nans, then the whole thing returns
1674 // true.
1675 if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
1676 return ConstantInt::getTrue(LHS->getContext());
1677
1678 // Otherwise, no need to compare the two constants, compare the
1679 // rest.
1680 return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
1681 }
1682
1683 // Handle vector zeros. This occurs because the canonical form of
1684 // "fcmp uno x,x" is "fcmp uno x, 0".
1685 if (isa<ConstantAggregateZero>(LHS->getOperand(1)) &&
1686 isa<ConstantAggregateZero>(RHS->getOperand(1)))
1687 return Builder->CreateFCmpUNO(LHS->getOperand(0), RHS->getOperand(0));
1688
1689 return 0;
1690 }
1691
1692 Value *Op0LHS = LHS->getOperand(0), *Op0RHS = LHS->getOperand(1);
1693 Value *Op1LHS = RHS->getOperand(0), *Op1RHS = RHS->getOperand(1);
1694 FCmpInst::Predicate Op0CC = LHS->getPredicate(), Op1CC = RHS->getPredicate();
1695
1696 if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
1697 // Swap RHS operands to match LHS.
1698 Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
1699 std::swap(Op1LHS, Op1RHS);
1700 }
1701 if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
1702 // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
1703 if (Op0CC == Op1CC)
1704 return Builder->CreateFCmp((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
1705 if (Op0CC == FCmpInst::FCMP_TRUE || Op1CC == FCmpInst::FCMP_TRUE)
1706 return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
1707 if (Op0CC == FCmpInst::FCMP_FALSE)
1708 return RHS;
1709 if (Op1CC == FCmpInst::FCMP_FALSE)
1710 return LHS;
1711 bool Op0Ordered;
1712 bool Op1Ordered;
1713 unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
1714 unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
1715 if (Op0Ordered == Op1Ordered) {
1716 // If both are ordered or unordered, return a new fcmp with
1717 // or'ed predicates.
1718 return getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, Op0LHS, Op0RHS, Builder);
1719 }
1720 }
1721 return 0;
1722 }
1723
1724 /// FoldOrWithConstants - This helper function folds:
1725 ///
1726 /// ((A | B) & C1) | (B & C2)
1727 ///
1728 /// into:
1729 ///
1730 /// (A & C1) | B
1731 ///
1732 /// when the XOR of the two constants is "all ones" (-1).
FoldOrWithConstants(BinaryOperator & I,Value * Op,Value * A,Value * B,Value * C)1733 Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
1734 Value *A, Value *B, Value *C) {
1735 ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
1736 if (!CI1) return 0;
1737
1738 Value *V1 = 0;
1739 ConstantInt *CI2 = 0;
1740 if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
1741
1742 APInt Xor = CI1->getValue() ^ CI2->getValue();
1743 if (!Xor.isAllOnesValue()) return 0;
1744
1745 if (V1 == A || V1 == B) {
1746 Value *NewOp = Builder->CreateAnd((V1 == A) ? B : A, CI1);
1747 return BinaryOperator::CreateOr(NewOp, V1);
1748 }
1749
1750 return 0;
1751 }
1752
visitOr(BinaryOperator & I)1753 Instruction *InstCombiner::visitOr(BinaryOperator &I) {
1754 bool Changed = SimplifyAssociativeOrCommutative(I);
1755 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1756
1757 if (Value *V = SimplifyOrInst(Op0, Op1, TD))
1758 return ReplaceInstUsesWith(I, V);
1759
1760 // (A&B)|(A&C) -> A&(B|C) etc
1761 if (Value *V = SimplifyUsingDistributiveLaws(I))
1762 return ReplaceInstUsesWith(I, V);
1763
1764 // See if we can simplify any instructions used by the instruction whose sole
1765 // purpose is to compute bits we don't care about.
1766 if (SimplifyDemandedInstructionBits(I))
1767 return &I;
1768
1769 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
1770 ConstantInt *C1 = 0; Value *X = 0;
1771 // (X & C1) | C2 --> (X | C2) & (C1|C2)
1772 // iff (C1 & C2) == 0.
1773 if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) &&
1774 (RHS->getValue() & C1->getValue()) != 0 &&
1775 Op0->hasOneUse()) {
1776 Value *Or = Builder->CreateOr(X, RHS);
1777 Or->takeName(Op0);
1778 return BinaryOperator::CreateAnd(Or,
1779 ConstantInt::get(I.getContext(),
1780 RHS->getValue() | C1->getValue()));
1781 }
1782
1783 // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
1784 if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
1785 Op0->hasOneUse()) {
1786 Value *Or = Builder->CreateOr(X, RHS);
1787 Or->takeName(Op0);
1788 return BinaryOperator::CreateXor(Or,
1789 ConstantInt::get(I.getContext(),
1790 C1->getValue() & ~RHS->getValue()));
1791 }
1792
1793 // Try to fold constant and into select arguments.
1794 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
1795 if (Instruction *R = FoldOpIntoSelect(I, SI))
1796 return R;
1797
1798 if (isa<PHINode>(Op0))
1799 if (Instruction *NV = FoldOpIntoPhi(I))
1800 return NV;
1801 }
1802
1803 Value *A = 0, *B = 0;
1804 ConstantInt *C1 = 0, *C2 = 0;
1805
1806 // (A | B) | C and A | (B | C) -> bswap if possible.
1807 // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
1808 if (match(Op0, m_Or(m_Value(), m_Value())) ||
1809 match(Op1, m_Or(m_Value(), m_Value())) ||
1810 (match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
1811 match(Op1, m_LogicalShift(m_Value(), m_Value())))) {
1812 if (Instruction *BSwap = MatchBSwap(I))
1813 return BSwap;
1814 }
1815
1816 // (X^C)|Y -> (X|Y)^C iff Y&C == 0
1817 if (Op0->hasOneUse() &&
1818 match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1819 MaskedValueIsZero(Op1, C1->getValue())) {
1820 Value *NOr = Builder->CreateOr(A, Op1);
1821 NOr->takeName(Op0);
1822 return BinaryOperator::CreateXor(NOr, C1);
1823 }
1824
1825 // Y|(X^C) -> (X|Y)^C iff Y&C == 0
1826 if (Op1->hasOneUse() &&
1827 match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
1828 MaskedValueIsZero(Op0, C1->getValue())) {
1829 Value *NOr = Builder->CreateOr(A, Op0);
1830 NOr->takeName(Op0);
1831 return BinaryOperator::CreateXor(NOr, C1);
1832 }
1833
1834 // (A & C)|(B & D)
1835 Value *C = 0, *D = 0;
1836 if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
1837 match(Op1, m_And(m_Value(B), m_Value(D)))) {
1838 Value *V1 = 0, *V2 = 0;
1839 C1 = dyn_cast<ConstantInt>(C);
1840 C2 = dyn_cast<ConstantInt>(D);
1841 if (C1 && C2) { // (A & C1)|(B & C2)
1842 // If we have: ((V + N) & C1) | (V & C2)
1843 // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
1844 // replace with V+N.
1845 if (C1->getValue() == ~C2->getValue()) {
1846 if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
1847 match(A, m_Add(m_Value(V1), m_Value(V2)))) {
1848 // Add commutes, try both ways.
1849 if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
1850 return ReplaceInstUsesWith(I, A);
1851 if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
1852 return ReplaceInstUsesWith(I, A);
1853 }
1854 // Or commutes, try both ways.
1855 if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
1856 match(B, m_Add(m_Value(V1), m_Value(V2)))) {
1857 // Add commutes, try both ways.
1858 if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
1859 return ReplaceInstUsesWith(I, B);
1860 if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
1861 return ReplaceInstUsesWith(I, B);
1862 }
1863 }
1864
1865 if ((C1->getValue() & C2->getValue()) == 0) {
1866 // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2)
1867 // iff (C1&C2) == 0 and (N&~C1) == 0
1868 if (match(A, m_Or(m_Value(V1), m_Value(V2))) &&
1869 ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N)
1870 (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V)
1871 return BinaryOperator::CreateAnd(A,
1872 ConstantInt::get(A->getContext(),
1873 C1->getValue()|C2->getValue()));
1874 // Or commutes, try both ways.
1875 if (match(B, m_Or(m_Value(V1), m_Value(V2))) &&
1876 ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N)
1877 (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V)
1878 return BinaryOperator::CreateAnd(B,
1879 ConstantInt::get(B->getContext(),
1880 C1->getValue()|C2->getValue()));
1881
1882 // ((V|C3)&C1) | ((V|C4)&C2) --> (V|C3|C4)&(C1|C2)
1883 // iff (C1&C2) == 0 and (C3&~C1) == 0 and (C4&~C2) == 0.
1884 ConstantInt *C3 = 0, *C4 = 0;
1885 if (match(A, m_Or(m_Value(V1), m_ConstantInt(C3))) &&
1886 (C3->getValue() & ~C1->getValue()) == 0 &&
1887 match(B, m_Or(m_Specific(V1), m_ConstantInt(C4))) &&
1888 (C4->getValue() & ~C2->getValue()) == 0) {
1889 V2 = Builder->CreateOr(V1, ConstantExpr::getOr(C3, C4), "bitfield");
1890 return BinaryOperator::CreateAnd(V2,
1891 ConstantInt::get(B->getContext(),
1892 C1->getValue()|C2->getValue()));
1893 }
1894 }
1895 }
1896
1897 // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants.
1898 // Don't do this for vector select idioms, the code generator doesn't handle
1899 // them well yet.
1900 if (!I.getType()->isVectorTy()) {
1901 if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
1902 return Match;
1903 if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
1904 return Match;
1905 if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
1906 return Match;
1907 if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
1908 return Match;
1909 }
1910
1911 // ((A&~B)|(~A&B)) -> A^B
1912 if ((match(C, m_Not(m_Specific(D))) &&
1913 match(B, m_Not(m_Specific(A)))))
1914 return BinaryOperator::CreateXor(A, D);
1915 // ((~B&A)|(~A&B)) -> A^B
1916 if ((match(A, m_Not(m_Specific(D))) &&
1917 match(B, m_Not(m_Specific(C)))))
1918 return BinaryOperator::CreateXor(C, D);
1919 // ((A&~B)|(B&~A)) -> A^B
1920 if ((match(C, m_Not(m_Specific(B))) &&
1921 match(D, m_Not(m_Specific(A)))))
1922 return BinaryOperator::CreateXor(A, B);
1923 // ((~B&A)|(B&~A)) -> A^B
1924 if ((match(A, m_Not(m_Specific(B))) &&
1925 match(D, m_Not(m_Specific(C)))))
1926 return BinaryOperator::CreateXor(C, B);
1927
1928 // ((A|B)&1)|(B&-2) -> (A&1) | B
1929 if (match(A, m_Or(m_Value(V1), m_Specific(B))) ||
1930 match(A, m_Or(m_Specific(B), m_Value(V1)))) {
1931 Instruction *Ret = FoldOrWithConstants(I, Op1, V1, B, C);
1932 if (Ret) return Ret;
1933 }
1934 // (B&-2)|((A|B)&1) -> (A&1) | B
1935 if (match(B, m_Or(m_Specific(A), m_Value(V1))) ||
1936 match(B, m_Or(m_Value(V1), m_Specific(A)))) {
1937 Instruction *Ret = FoldOrWithConstants(I, Op0, A, V1, D);
1938 if (Ret) return Ret;
1939 }
1940 }
1941
1942 // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
1943 if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
1944 if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
1945 if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
1946 SI0->getOperand(1) == SI1->getOperand(1) &&
1947 (SI0->hasOneUse() || SI1->hasOneUse())) {
1948 Value *NewOp = Builder->CreateOr(SI0->getOperand(0), SI1->getOperand(0),
1949 SI0->getName());
1950 return BinaryOperator::Create(SI1->getOpcode(), NewOp,
1951 SI1->getOperand(1));
1952 }
1953 }
1954
1955 // (~A | ~B) == (~(A & B)) - De Morgan's Law
1956 if (Value *Op0NotVal = dyn_castNotVal(Op0))
1957 if (Value *Op1NotVal = dyn_castNotVal(Op1))
1958 if (Op0->hasOneUse() && Op1->hasOneUse()) {
1959 Value *And = Builder->CreateAnd(Op0NotVal, Op1NotVal,
1960 I.getName()+".demorgan");
1961 return BinaryOperator::CreateNot(And);
1962 }
1963
1964 // Canonicalize xor to the RHS.
1965 if (match(Op0, m_Xor(m_Value(), m_Value())))
1966 std::swap(Op0, Op1);
1967
1968 // A | ( A ^ B) -> A | B
1969 // A | (~A ^ B) -> A | ~B
1970 if (match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
1971 if (Op0 == A || Op0 == B)
1972 return BinaryOperator::CreateOr(A, B);
1973
1974 if (Op1->hasOneUse() && match(A, m_Not(m_Specific(Op0)))) {
1975 Value *Not = Builder->CreateNot(B, B->getName()+".not");
1976 return BinaryOperator::CreateOr(Not, Op0);
1977 }
1978 if (Op1->hasOneUse() && match(B, m_Not(m_Specific(Op0)))) {
1979 Value *Not = Builder->CreateNot(A, A->getName()+".not");
1980 return BinaryOperator::CreateOr(Not, Op0);
1981 }
1982 }
1983
1984 // A | ~(A | B) -> A | ~B
1985 // A | ~(A ^ B) -> A | ~B
1986 if (match(Op1, m_Not(m_Value(A))))
1987 if (BinaryOperator *B = dyn_cast<BinaryOperator>(A))
1988 if ((Op0 == B->getOperand(0) || Op0 == B->getOperand(1)) &&
1989 Op1->hasOneUse() && (B->getOpcode() == Instruction::Or ||
1990 B->getOpcode() == Instruction::Xor)) {
1991 Value *NotOp = Op0 == B->getOperand(0) ? B->getOperand(1) :
1992 B->getOperand(0);
1993 Value *Not = Builder->CreateNot(NotOp, NotOp->getName()+".not");
1994 return BinaryOperator::CreateOr(Not, Op0);
1995 }
1996
1997 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
1998 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
1999 if (Value *Res = FoldOrOfICmps(LHS, RHS))
2000 return ReplaceInstUsesWith(I, Res);
2001
2002 // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
2003 if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0)))
2004 if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1)))
2005 if (Value *Res = FoldOrOfFCmps(LHS, RHS))
2006 return ReplaceInstUsesWith(I, Res);
2007
2008 // fold (or (cast A), (cast B)) -> (cast (or A, B))
2009 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
2010 CastInst *Op1C = dyn_cast<CastInst>(Op1);
2011 if (Op1C && Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
2012 Type *SrcTy = Op0C->getOperand(0)->getType();
2013 if (SrcTy == Op1C->getOperand(0)->getType() &&
2014 SrcTy->isIntOrIntVectorTy()) {
2015 Value *Op0COp = Op0C->getOperand(0), *Op1COp = Op1C->getOperand(0);
2016
2017 if ((!isa<ICmpInst>(Op0COp) || !isa<ICmpInst>(Op1COp)) &&
2018 // Only do this if the casts both really cause code to be
2019 // generated.
2020 ShouldOptimizeCast(Op0C->getOpcode(), Op0COp, I.getType()) &&
2021 ShouldOptimizeCast(Op1C->getOpcode(), Op1COp, I.getType())) {
2022 Value *NewOp = Builder->CreateOr(Op0COp, Op1COp, I.getName());
2023 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
2024 }
2025
2026 // If this is or(cast(icmp), cast(icmp)), try to fold this even if the
2027 // cast is otherwise not optimizable. This happens for vector sexts.
2028 if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1COp))
2029 if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0COp))
2030 if (Value *Res = FoldOrOfICmps(LHS, RHS))
2031 return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
2032
2033 // If this is or(cast(fcmp), cast(fcmp)), try to fold this even if the
2034 // cast is otherwise not optimizable. This happens for vector sexts.
2035 if (FCmpInst *RHS = dyn_cast<FCmpInst>(Op1COp))
2036 if (FCmpInst *LHS = dyn_cast<FCmpInst>(Op0COp))
2037 if (Value *Res = FoldOrOfFCmps(LHS, RHS))
2038 return CastInst::Create(Op0C->getOpcode(), Res, I.getType());
2039 }
2040 }
2041 }
2042
2043 // or(sext(A), B) -> A ? -1 : B where A is an i1
2044 // or(A, sext(B)) -> B ? -1 : A where B is an i1
2045 if (match(Op0, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
2046 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op1);
2047 if (match(Op1, m_SExt(m_Value(A))) && A->getType()->isIntegerTy(1))
2048 return SelectInst::Create(A, ConstantInt::getSigned(I.getType(), -1), Op0);
2049
2050 // Note: If we've gotten to the point of visiting the outer OR, then the
2051 // inner one couldn't be simplified. If it was a constant, then it won't
2052 // be simplified by a later pass either, so we try swapping the inner/outer
2053 // ORs in the hopes that we'll be able to simplify it this way.
2054 // (X|C) | V --> (X|V) | C
2055 if (Op0->hasOneUse() && !isa<ConstantInt>(Op1) &&
2056 match(Op0, m_Or(m_Value(A), m_ConstantInt(C1)))) {
2057 Value *Inner = Builder->CreateOr(A, Op1);
2058 Inner->takeName(Op0);
2059 return BinaryOperator::CreateOr(Inner, C1);
2060 }
2061
2062 return Changed ? &I : 0;
2063 }
2064
visitXor(BinaryOperator & I)2065 Instruction *InstCombiner::visitXor(BinaryOperator &I) {
2066 bool Changed = SimplifyAssociativeOrCommutative(I);
2067 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
2068
2069 if (Value *V = SimplifyXorInst(Op0, Op1, TD))
2070 return ReplaceInstUsesWith(I, V);
2071
2072 // (A&B)^(A&C) -> A&(B^C) etc
2073 if (Value *V = SimplifyUsingDistributiveLaws(I))
2074 return ReplaceInstUsesWith(I, V);
2075
2076 // See if we can simplify any instructions used by the instruction whose sole
2077 // purpose is to compute bits we don't care about.
2078 if (SimplifyDemandedInstructionBits(I))
2079 return &I;
2080
2081 // Is this a ~ operation?
2082 if (Value *NotOp = dyn_castNotVal(&I)) {
2083 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
2084 if (Op0I->getOpcode() == Instruction::And ||
2085 Op0I->getOpcode() == Instruction::Or) {
2086 // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
2087 // ~(~X | Y) === (X & ~Y) - De Morgan's Law
2088 if (dyn_castNotVal(Op0I->getOperand(1)))
2089 Op0I->swapOperands();
2090 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
2091 Value *NotY =
2092 Builder->CreateNot(Op0I->getOperand(1),
2093 Op0I->getOperand(1)->getName()+".not");
2094 if (Op0I->getOpcode() == Instruction::And)
2095 return BinaryOperator::CreateOr(Op0NotVal, NotY);
2096 return BinaryOperator::CreateAnd(Op0NotVal, NotY);
2097 }
2098
2099 // ~(X & Y) --> (~X | ~Y) - De Morgan's Law
2100 // ~(X | Y) === (~X & ~Y) - De Morgan's Law
2101 if (isFreeToInvert(Op0I->getOperand(0)) &&
2102 isFreeToInvert(Op0I->getOperand(1))) {
2103 Value *NotX =
2104 Builder->CreateNot(Op0I->getOperand(0), "notlhs");
2105 Value *NotY =
2106 Builder->CreateNot(Op0I->getOperand(1), "notrhs");
2107 if (Op0I->getOpcode() == Instruction::And)
2108 return BinaryOperator::CreateOr(NotX, NotY);
2109 return BinaryOperator::CreateAnd(NotX, NotY);
2110 }
2111
2112 } else if (Op0I->getOpcode() == Instruction::AShr) {
2113 // ~(~X >>s Y) --> (X >>s Y)
2114 if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0)))
2115 return BinaryOperator::CreateAShr(Op0NotVal, Op0I->getOperand(1));
2116 }
2117 }
2118 }
2119
2120
2121 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
2122 if (RHS->isOne() && Op0->hasOneUse())
2123 // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
2124 if (CmpInst *CI = dyn_cast<CmpInst>(Op0))
2125 return CmpInst::Create(CI->getOpcode(),
2126 CI->getInversePredicate(),
2127 CI->getOperand(0), CI->getOperand(1));
2128
2129 // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
2130 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
2131 if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
2132 if (CI->hasOneUse() && Op0C->hasOneUse()) {
2133 Instruction::CastOps Opcode = Op0C->getOpcode();
2134 if ((Opcode == Instruction::ZExt || Opcode == Instruction::SExt) &&
2135 (RHS == ConstantExpr::getCast(Opcode,
2136 ConstantInt::getTrue(I.getContext()),
2137 Op0C->getDestTy()))) {
2138 CI->setPredicate(CI->getInversePredicate());
2139 return CastInst::Create(Opcode, CI, Op0C->getType());
2140 }
2141 }
2142 }
2143 }
2144
2145 if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
2146 // ~(c-X) == X-c-1 == X+(-c-1)
2147 if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
2148 if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
2149 Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
2150 Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
2151 ConstantInt::get(I.getType(), 1));
2152 return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
2153 }
2154
2155 if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
2156 if (Op0I->getOpcode() == Instruction::Add) {
2157 // ~(X-c) --> (-c-1)-X
2158 if (RHS->isAllOnesValue()) {
2159 Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
2160 return BinaryOperator::CreateSub(
2161 ConstantExpr::getSub(NegOp0CI,
2162 ConstantInt::get(I.getType(), 1)),
2163 Op0I->getOperand(0));
2164 } else if (RHS->getValue().isSignBit()) {
2165 // (X + C) ^ signbit -> (X + C + signbit)
2166 Constant *C = ConstantInt::get(I.getContext(),
2167 RHS->getValue() + Op0CI->getValue());
2168 return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
2169
2170 }
2171 } else if (Op0I->getOpcode() == Instruction::Or) {
2172 // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
2173 if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
2174 Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
2175 // Anything in both C1 and C2 is known to be zero, remove it from
2176 // NewRHS.
2177 Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS);
2178 NewRHS = ConstantExpr::getAnd(NewRHS,
2179 ConstantExpr::getNot(CommonBits));
2180 Worklist.Add(Op0I);
2181 I.setOperand(0, Op0I->getOperand(0));
2182 I.setOperand(1, NewRHS);
2183 return &I;
2184 }
2185 }
2186 }
2187 }
2188
2189 // Try to fold constant and into select arguments.
2190 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
2191 if (Instruction *R = FoldOpIntoSelect(I, SI))
2192 return R;
2193 if (isa<PHINode>(Op0))
2194 if (Instruction *NV = FoldOpIntoPhi(I))
2195 return NV;
2196 }
2197
2198 BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
2199 if (Op1I) {
2200 Value *A, *B;
2201 if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
2202 if (A == Op0) { // B^(B|A) == (A|B)^B
2203 Op1I->swapOperands();
2204 I.swapOperands();
2205 std::swap(Op0, Op1);
2206 } else if (B == Op0) { // B^(A|B) == (A|B)^B
2207 I.swapOperands(); // Simplified below.
2208 std::swap(Op0, Op1);
2209 }
2210 } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) &&
2211 Op1I->hasOneUse()){
2212 if (A == Op0) { // A^(A&B) -> A^(B&A)
2213 Op1I->swapOperands();
2214 std::swap(A, B);
2215 }
2216 if (B == Op0) { // A^(B&A) -> (B&A)^A
2217 I.swapOperands(); // Simplified below.
2218 std::swap(Op0, Op1);
2219 }
2220 }
2221 }
2222
2223 BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
2224 if (Op0I) {
2225 Value *A, *B;
2226 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
2227 Op0I->hasOneUse()) {
2228 if (A == Op1) // (B|A)^B == (A|B)^B
2229 std::swap(A, B);
2230 if (B == Op1) // (A|B)^B == A & ~B
2231 return BinaryOperator::CreateAnd(A, Builder->CreateNot(Op1));
2232 } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
2233 Op0I->hasOneUse()){
2234 if (A == Op1) // (A&B)^A -> (B&A)^A
2235 std::swap(A, B);
2236 if (B == Op1 && // (B&A)^A == ~B & A
2237 !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
2238 return BinaryOperator::CreateAnd(Builder->CreateNot(A), Op1);
2239 }
2240 }
2241 }
2242
2243 // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
2244 if (Op0I && Op1I && Op0I->isShift() &&
2245 Op0I->getOpcode() == Op1I->getOpcode() &&
2246 Op0I->getOperand(1) == Op1I->getOperand(1) &&
2247 (Op1I->hasOneUse() || Op1I->hasOneUse())) {
2248 Value *NewOp =
2249 Builder->CreateXor(Op0I->getOperand(0), Op1I->getOperand(0),
2250 Op0I->getName());
2251 return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
2252 Op1I->getOperand(1));
2253 }
2254
2255 if (Op0I && Op1I) {
2256 Value *A, *B, *C, *D;
2257 // (A & B)^(A | B) -> A ^ B
2258 if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
2259 match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
2260 if ((A == C && B == D) || (A == D && B == C))
2261 return BinaryOperator::CreateXor(A, B);
2262 }
2263 // (A | B)^(A & B) -> A ^ B
2264 if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
2265 match(Op1I, m_And(m_Value(C), m_Value(D)))) {
2266 if ((A == C && B == D) || (A == D && B == C))
2267 return BinaryOperator::CreateXor(A, B);
2268 }
2269 }
2270
2271 // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
2272 if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
2273 if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
2274 if (PredicatesFoldable(LHS->getPredicate(), RHS->getPredicate())) {
2275 if (LHS->getOperand(0) == RHS->getOperand(1) &&
2276 LHS->getOperand(1) == RHS->getOperand(0))
2277 LHS->swapOperands();
2278 if (LHS->getOperand(0) == RHS->getOperand(0) &&
2279 LHS->getOperand(1) == RHS->getOperand(1)) {
2280 Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
2281 unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
2282 bool isSigned = LHS->isSigned() || RHS->isSigned();
2283 return ReplaceInstUsesWith(I,
2284 getICmpValue(isSigned, Code, Op0, Op1, Builder));
2285 }
2286 }
2287
2288 // fold (xor (cast A), (cast B)) -> (cast (xor A, B))
2289 if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
2290 if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
2291 if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
2292 Type *SrcTy = Op0C->getOperand(0)->getType();
2293 if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegerTy() &&
2294 // Only do this if the casts both really cause code to be generated.
2295 ShouldOptimizeCast(Op0C->getOpcode(), Op0C->getOperand(0),
2296 I.getType()) &&
2297 ShouldOptimizeCast(Op1C->getOpcode(), Op1C->getOperand(0),
2298 I.getType())) {
2299 Value *NewOp = Builder->CreateXor(Op0C->getOperand(0),
2300 Op1C->getOperand(0), I.getName());
2301 return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
2302 }
2303 }
2304 }
2305
2306 return Changed ? &I : 0;
2307 }
2308