1//===- InstCombineAddSub.cpp ------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the visit functions for add, fadd, sub, and fsub.
10//
11//===----------------------------------------------------------------------===//
12
13#include "InstCombineInternal.h"
14#include "llvm/ADT/APFloat.h"
15#include "llvm/ADT/APInt.h"
16#include "llvm/ADT/STLExtras.h"
17#include "llvm/ADT/SmallVector.h"
18#include "llvm/Analysis/InstructionSimplify.h"
19#include "llvm/Analysis/ValueTracking.h"
20#include "llvm/IR/Constant.h"
21#include "llvm/IR/Constants.h"
22#include "llvm/IR/InstrTypes.h"
23#include "llvm/IR/Instruction.h"
24#include "llvm/IR/Instructions.h"
25#include "llvm/IR/Operator.h"
26#include "llvm/IR/PatternMatch.h"
27#include "llvm/IR/Type.h"
28#include "llvm/IR/Value.h"
29#include "llvm/Support/AlignOf.h"
30#include "llvm/Support/Casting.h"
31#include "llvm/Support/KnownBits.h"
32#include "llvm/Transforms/InstCombine/InstCombiner.h"
33#include <cassert>
34#include <utility>
35
36using namespace llvm;
37using namespace PatternMatch;
38
39#define DEBUG_TYPE "instcombine"
40
41namespace {
42
43 /// Class representing coefficient of floating-point addend.
44 /// This class needs to be highly efficient, which is especially true for
45 /// the constructor. As of I write this comment, the cost of the default
46 /// constructor is merely 4-byte-store-zero (Assuming compiler is able to
47 /// perform write-merging).
48 ///
49 class FAddendCoef {
50 public:
51 // The constructor has to initialize a APFloat, which is unnecessary for
52 // most addends which have coefficient either 1 or -1. So, the constructor
53 // is expensive. In order to avoid the cost of the constructor, we should
54 // reuse some instances whenever possible. The pre-created instances
55 // FAddCombine::Add[0-5] embodies this idea.
56 FAddendCoef() = default;
57 ~FAddendCoef();
58
59 // If possible, don't define operator+/operator- etc because these
60 // operators inevitably call FAddendCoef's constructor which is not cheap.
61 void operator=(const FAddendCoef &A);
62 void operator+=(const FAddendCoef &A);
63 void operator*=(const FAddendCoef &S);
64
65 void set(short C) {
66 assert(!insaneIntVal(C) && "Insane coefficient");
67 IsFp = false; IntVal = C;
68 }
69
70 void set(const APFloat& C);
71
72 void negate();
73
74 bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); }
75 Value *getValue(Type *) const;
76
77 bool isOne() const { return isInt() && IntVal == 1; }
78 bool isTwo() const { return isInt() && IntVal == 2; }
79 bool isMinusOne() const { return isInt() && IntVal == -1; }
80 bool isMinusTwo() const { return isInt() && IntVal == -2; }
81
82 private:
83 bool insaneIntVal(int V) { return V > 4 || V < -4; }
84
85 APFloat *getFpValPtr() { return reinterpret_cast<APFloat *>(&FpValBuf); }
86
87 const APFloat *getFpValPtr() const {
88 return reinterpret_cast<const APFloat *>(&FpValBuf);
89 }
90
91 const APFloat &getFpVal() const {
92 assert(IsFp && BufHasFpVal && "Incorret state");
93 return *getFpValPtr();
94 }
95
96 APFloat &getFpVal() {
97 assert(IsFp && BufHasFpVal && "Incorret state");
98 return *getFpValPtr();
99 }
100
101 bool isInt() const { return !IsFp; }
102
103 // If the coefficient is represented by an integer, promote it to a
104 // floating point.
105 void convertToFpType(const fltSemantics &Sem);
106
107 // Construct an APFloat from a signed integer.
108 // TODO: We should get rid of this function when APFloat can be constructed
109 // from an *SIGNED* integer.
110 APFloat createAPFloatFromInt(const fltSemantics &Sem, int Val);
111
112 bool IsFp = false;
113
114 // True iff FpValBuf contains an instance of APFloat.
115 bool BufHasFpVal = false;
116
117 // The integer coefficient of an individual addend is either 1 or -1,
118 // and we try to simplify at most 4 addends from neighboring at most
119 // two instructions. So the range of <IntVal> falls in [-4, 4]. APInt
120 // is overkill of this end.
121 short IntVal = 0;
122
123 AlignedCharArrayUnion<APFloat> FpValBuf;
124 };
125
126 /// FAddend is used to represent floating-point addend. An addend is
127 /// represented as <C, V>, where the V is a symbolic value, and C is a
128 /// constant coefficient. A constant addend is represented as <C, 0>.
129 class FAddend {
130 public:
131 FAddend() = default;
132
133 void operator+=(const FAddend &T) {
134 assert((Val == T.Val) && "Symbolic-values disagree");
135 Coeff += T.Coeff;
136 }
137
138 Value *getSymVal() const { return Val; }
139 const FAddendCoef &getCoef() const { return Coeff; }
140
141 bool isConstant() const { return Val == nullptr; }
142 bool isZero() const { return Coeff.isZero(); }
143
144 void set(short Coefficient, Value *V) {
145 Coeff.set(Coefficient);
146 Val = V;
147 }
148 void set(const APFloat &Coefficient, Value *V) {
149 Coeff.set(Coefficient);
150 Val = V;
151 }
152 void set(const ConstantFP *Coefficient, Value *V) {
153 Coeff.set(Coefficient->getValueAPF());
154 Val = V;
155 }
156
157 void negate() { Coeff.negate(); }
158
159 /// Drill down the U-D chain one step to find the definition of V, and
160 /// try to break the definition into one or two addends.
161 static unsigned drillValueDownOneStep(Value* V, FAddend &A0, FAddend &A1);
162
163 /// Similar to FAddend::drillDownOneStep() except that the value being
164 /// splitted is the addend itself.
165 unsigned drillAddendDownOneStep(FAddend &Addend0, FAddend &Addend1) const;
166
167 private:
168 void Scale(const FAddendCoef& ScaleAmt) { Coeff *= ScaleAmt; }
169
170 // This addend has the value of "Coeff * Val".
171 Value *Val = nullptr;
172 FAddendCoef Coeff;
173 };
174
175 /// FAddCombine is the class for optimizing an unsafe fadd/fsub along
176 /// with its neighboring at most two instructions.
177 ///
178 class FAddCombine {
179 public:
180 FAddCombine(InstCombiner::BuilderTy &B) : Builder(B) {}
181
182 Value *simplify(Instruction *FAdd);
183
184 private:
185 using AddendVect = SmallVector<const FAddend *, 4>;
186
187 Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);
188
189 /// Convert given addend to a Value
190 Value *createAddendVal(const FAddend &A, bool& NeedNeg);
191
192 /// Return the number of instructions needed to emit the N-ary addition.
193 unsigned calcInstrNumber(const AddendVect& Vect);
194
195 Value *createFSub(Value *Opnd0, Value *Opnd1);
196 Value *createFAdd(Value *Opnd0, Value *Opnd1);
197 Value *createFMul(Value *Opnd0, Value *Opnd1);
198 Value *createFNeg(Value *V);
199 Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
200 void createInstPostProc(Instruction *NewInst, bool NoNumber = false);
201
202 // Debugging stuff are clustered here.
203 #ifndef NDEBUG
204 unsigned CreateInstrNum;
205 void initCreateInstNum() { CreateInstrNum = 0; }
206 void incCreateInstNum() { CreateInstrNum++; }
207 #else
208 void initCreateInstNum() {}
209 void incCreateInstNum() {}
210 #endif
211
212 InstCombiner::BuilderTy &Builder;
213 Instruction *Instr = nullptr;
214 };
215
216} // end anonymous namespace
217
218//===----------------------------------------------------------------------===//
219//
220// Implementation of
221// {FAddendCoef, FAddend, FAddition, FAddCombine}.
222//
223//===----------------------------------------------------------------------===//
224FAddendCoef::~FAddendCoef() {
225 if (BufHasFpVal)
226 getFpValPtr()->~APFloat();
227}
228
229void FAddendCoef::set(const APFloat& C) {
230 APFloat *P = getFpValPtr();
231
232 if (isInt()) {
233 // As the buffer is meanless byte stream, we cannot call
234 // APFloat::operator=().
235 new(P) APFloat(C);
236 } else
237 *P = C;
238
239 IsFp = BufHasFpVal = true;
240}
241
242void FAddendCoef::convertToFpType(const fltSemantics &Sem) {
243 if (!isInt())
244 return;
245
246 APFloat *P = getFpValPtr();
247 if (IntVal > 0)
248 new(P) APFloat(Sem, IntVal);
249 else {
250 new(P) APFloat(Sem, 0 - IntVal);
251 P->changeSign();
252 }
253 IsFp = BufHasFpVal = true;
254}
255
256APFloat FAddendCoef::createAPFloatFromInt(const fltSemantics &Sem, int Val) {
257 if (Val >= 0)
258 return APFloat(Sem, Val);
259
260 APFloat T(Sem, 0 - Val);
261 T.changeSign();
262
263 return T;
264}
265
266void FAddendCoef::operator=(const FAddendCoef &That) {
267 if (That.isInt())
268 set(That.IntVal);
269 else
270 set(That.getFpVal());
271}
272
273void FAddendCoef::operator+=(const FAddendCoef &That) {
274 RoundingMode RndMode = RoundingMode::NearestTiesToEven;
275 if (isInt() == That.isInt()) {
276 if (isInt())
277 IntVal += That.IntVal;
278 else
279 getFpVal().add(RHS: That.getFpVal(), RM: RndMode);
280 return;
281 }
282
283 if (isInt()) {
284 const APFloat &T = That.getFpVal();
285 convertToFpType(Sem: T.getSemantics());
286 getFpVal().add(RHS: T, RM: RndMode);
287 return;
288 }
289
290 APFloat &T = getFpVal();
291 T.add(RHS: createAPFloatFromInt(Sem: T.getSemantics(), Val: That.IntVal), RM: RndMode);
292}
293
294void FAddendCoef::operator*=(const FAddendCoef &That) {
295 if (That.isOne())
296 return;
297
298 if (That.isMinusOne()) {
299 negate();
300 return;
301 }
302
303 if (isInt() && That.isInt()) {
304 int Res = IntVal * (int)That.IntVal;
305 assert(!insaneIntVal(Res) && "Insane int value");
306 IntVal = Res;
307 return;
308 }
309
310 const fltSemantics &Semantic =
311 isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics();
312
313 if (isInt())
314 convertToFpType(Sem: Semantic);
315 APFloat &F0 = getFpVal();
316
317 if (That.isInt())
318 F0.multiply(RHS: createAPFloatFromInt(Sem: Semantic, Val: That.IntVal),
319 RM: APFloat::rmNearestTiesToEven);
320 else
321 F0.multiply(RHS: That.getFpVal(), RM: APFloat::rmNearestTiesToEven);
322}
323
324void FAddendCoef::negate() {
325 if (isInt())
326 IntVal = 0 - IntVal;
327 else
328 getFpVal().changeSign();
329}
330
331Value *FAddendCoef::getValue(Type *Ty) const {
332 return isInt() ?
333 ConstantFP::get(Ty, V: float(IntVal)) :
334 ConstantFP::get(Context&: Ty->getContext(), V: getFpVal());
335}
336
337// The definition of <Val> Addends
338// =========================================
339// A + B <1, A>, <1,B>
340// A - B <1, A>, <1,B>
341// 0 - B <-1, B>
342// C * A, <C, A>
343// A + C <1, A> <C, NULL>
344// 0 +/- 0 <0, NULL> (corner case)
345//
346// Legend: A and B are not constant, C is constant
347unsigned FAddend::drillValueDownOneStep
348 (Value *Val, FAddend &Addend0, FAddend &Addend1) {
349 Instruction *I = nullptr;
350 if (!Val || !(I = dyn_cast<Instruction>(Val)))
351 return 0;
352
353 unsigned Opcode = I->getOpcode();
354
355 if (Opcode == Instruction::FAdd || Opcode == Instruction::FSub) {
356 ConstantFP *C0, *C1;
357 Value *Opnd0 = I->getOperand(i: 0);
358 Value *Opnd1 = I->getOperand(i: 1);
359 if ((C0 = dyn_cast<ConstantFP>(Val: Opnd0)) && C0->isZero())
360 Opnd0 = nullptr;
361
362 if ((C1 = dyn_cast<ConstantFP>(Val: Opnd1)) && C1->isZero())
363 Opnd1 = nullptr;
364
365 if (Opnd0) {
366 if (!C0)
367 Addend0.set(Coefficient: 1, V: Opnd0);
368 else
369 Addend0.set(Coefficient: C0, V: nullptr);
370 }
371
372 if (Opnd1) {
373 FAddend &Addend = Opnd0 ? Addend1 : Addend0;
374 if (!C1)
375 Addend.set(Coefficient: 1, V: Opnd1);
376 else
377 Addend.set(Coefficient: C1, V: nullptr);
378 if (Opcode == Instruction::FSub)
379 Addend.negate();
380 }
381
382 if (Opnd0 || Opnd1)
383 return Opnd0 && Opnd1 ? 2 : 1;
384
385 // Both operands are zero. Weird!
386 Addend0.set(Coefficient: APFloat(C0->getValueAPF().getSemantics()), V: nullptr);
387 return 1;
388 }
389
390 if (I->getOpcode() == Instruction::FMul) {
391 Value *V0 = I->getOperand(i: 0);
392 Value *V1 = I->getOperand(i: 1);
393 if (ConstantFP *C = dyn_cast<ConstantFP>(Val: V0)) {
394 Addend0.set(Coefficient: C, V: V1);
395 return 1;
396 }
397
398 if (ConstantFP *C = dyn_cast<ConstantFP>(Val: V1)) {
399 Addend0.set(Coefficient: C, V: V0);
400 return 1;
401 }
402 }
403
404 return 0;
405}
406
407// Try to break *this* addend into two addends. e.g. Suppose this addend is
408// <2.3, V>, and V = X + Y, by calling this function, we obtain two addends,
409// i.e. <2.3, X> and <2.3, Y>.
410unsigned FAddend::drillAddendDownOneStep
411 (FAddend &Addend0, FAddend &Addend1) const {
412 if (isConstant())
413 return 0;
414
415 unsigned BreakNum = FAddend::drillValueDownOneStep(Val, Addend0, Addend1);
416 if (!BreakNum || Coeff.isOne())
417 return BreakNum;
418
419 Addend0.Scale(ScaleAmt: Coeff);
420
421 if (BreakNum == 2)
422 Addend1.Scale(ScaleAmt: Coeff);
423
424 return BreakNum;
425}
426
427Value *FAddCombine::simplify(Instruction *I) {
428 assert(I->hasAllowReassoc() && I->hasNoSignedZeros() &&
429 "Expected 'reassoc'+'nsz' instruction");
430
431 // Currently we are not able to handle vector type.
432 if (I->getType()->isVectorTy())
433 return nullptr;
434
435 assert((I->getOpcode() == Instruction::FAdd ||
436 I->getOpcode() == Instruction::FSub) && "Expect add/sub");
437
438 // Save the instruction before calling other member-functions.
439 Instr = I;
440
441 FAddend Opnd0, Opnd1, Opnd0_0, Opnd0_1, Opnd1_0, Opnd1_1;
442
443 unsigned OpndNum = FAddend::drillValueDownOneStep(Val: I, Addend0&: Opnd0, Addend1&: Opnd1);
444
445 // Step 1: Expand the 1st addend into Opnd0_0 and Opnd0_1.
446 unsigned Opnd0_ExpNum = 0;
447 unsigned Opnd1_ExpNum = 0;
448
449 if (!Opnd0.isConstant())
450 Opnd0_ExpNum = Opnd0.drillAddendDownOneStep(Addend0&: Opnd0_0, Addend1&: Opnd0_1);
451
452 // Step 2: Expand the 2nd addend into Opnd1_0 and Opnd1_1.
453 if (OpndNum == 2 && !Opnd1.isConstant())
454 Opnd1_ExpNum = Opnd1.drillAddendDownOneStep(Addend0&: Opnd1_0, Addend1&: Opnd1_1);
455
456 // Step 3: Try to optimize Opnd0_0 + Opnd0_1 + Opnd1_0 + Opnd1_1
457 if (Opnd0_ExpNum && Opnd1_ExpNum) {
458 AddendVect AllOpnds;
459 AllOpnds.push_back(Elt: &Opnd0_0);
460 AllOpnds.push_back(Elt: &Opnd1_0);
461 if (Opnd0_ExpNum == 2)
462 AllOpnds.push_back(Elt: &Opnd0_1);
463 if (Opnd1_ExpNum == 2)
464 AllOpnds.push_back(Elt: &Opnd1_1);
465
466 // Compute instruction quota. We should save at least one instruction.
467 unsigned InstQuota = 0;
468
469 Value *V0 = I->getOperand(i: 0);
470 Value *V1 = I->getOperand(i: 1);
471 InstQuota = ((!isa<Constant>(Val: V0) && V0->hasOneUse()) &&
472 (!isa<Constant>(Val: V1) && V1->hasOneUse())) ? 2 : 1;
473
474 if (Value *R = simplifyFAdd(V&: AllOpnds, InstrQuota: InstQuota))
475 return R;
476 }
477
478 if (OpndNum != 2) {
479 // The input instruction is : "I=0.0 +/- V". If the "V" were able to be
480 // splitted into two addends, say "V = X - Y", the instruction would have
481 // been optimized into "I = Y - X" in the previous steps.
482 //
483 const FAddendCoef &CE = Opnd0.getCoef();
484 return CE.isOne() ? Opnd0.getSymVal() : nullptr;
485 }
486
487 // step 4: Try to optimize Opnd0 + Opnd1_0 [+ Opnd1_1]
488 if (Opnd1_ExpNum) {
489 AddendVect AllOpnds;
490 AllOpnds.push_back(Elt: &Opnd0);
491 AllOpnds.push_back(Elt: &Opnd1_0);
492 if (Opnd1_ExpNum == 2)
493 AllOpnds.push_back(Elt: &Opnd1_1);
494
495 if (Value *R = simplifyFAdd(V&: AllOpnds, InstrQuota: 1))
496 return R;
497 }
498
499 // step 5: Try to optimize Opnd1 + Opnd0_0 [+ Opnd0_1]
500 if (Opnd0_ExpNum) {
501 AddendVect AllOpnds;
502 AllOpnds.push_back(Elt: &Opnd1);
503 AllOpnds.push_back(Elt: &Opnd0_0);
504 if (Opnd0_ExpNum == 2)
505 AllOpnds.push_back(Elt: &Opnd0_1);
506
507 if (Value *R = simplifyFAdd(V&: AllOpnds, InstrQuota: 1))
508 return R;
509 }
510
511 return nullptr;
512}
513
514Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
515 unsigned AddendNum = Addends.size();
516 assert(AddendNum <= 4 && "Too many addends");
517
518 // For saving intermediate results;
519 unsigned NextTmpIdx = 0;
520 FAddend TmpResult[3];
521
522 // Simplified addends are placed <SimpVect>.
523 AddendVect SimpVect;
524
525 // The outer loop works on one symbolic-value at a time. Suppose the input
526 // addends are : <a1, x>, <b1, y>, <a2, x>, <c1, z>, <b2, y>, ...
527 // The symbolic-values will be processed in this order: x, y, z.
528 for (unsigned SymIdx = 0; SymIdx < AddendNum; SymIdx++) {
529
530 const FAddend *ThisAddend = Addends[SymIdx];
531 if (!ThisAddend) {
532 // This addend was processed before.
533 continue;
534 }
535
536 Value *Val = ThisAddend->getSymVal();
537
538 // If the resulting expr has constant-addend, this constant-addend is
539 // desirable to reside at the top of the resulting expression tree. Placing
540 // constant close to super-expr(s) will potentially reveal some
541 // optimization opportunities in super-expr(s). Here we do not implement
542 // this logic intentionally and rely on SimplifyAssociativeOrCommutative
543 // call later.
544
545 unsigned StartIdx = SimpVect.size();
546 SimpVect.push_back(Elt: ThisAddend);
547
548 // The inner loop collects addends sharing same symbolic-value, and these
549 // addends will be later on folded into a single addend. Following above
550 // example, if the symbolic value "y" is being processed, the inner loop
551 // will collect two addends "<b1,y>" and "<b2,Y>". These two addends will
552 // be later on folded into "<b1+b2, y>".
553 for (unsigned SameSymIdx = SymIdx + 1;
554 SameSymIdx < AddendNum; SameSymIdx++) {
555 const FAddend *T = Addends[SameSymIdx];
556 if (T && T->getSymVal() == Val) {
557 // Set null such that next iteration of the outer loop will not process
558 // this addend again.
559 Addends[SameSymIdx] = nullptr;
560 SimpVect.push_back(Elt: T);
561 }
562 }
563
564 // If multiple addends share same symbolic value, fold them together.
565 if (StartIdx + 1 != SimpVect.size()) {
566 FAddend &R = TmpResult[NextTmpIdx ++];
567 R = *SimpVect[StartIdx];
568 for (unsigned Idx = StartIdx + 1; Idx < SimpVect.size(); Idx++)
569 R += *SimpVect[Idx];
570
571 // Pop all addends being folded and push the resulting folded addend.
572 SimpVect.resize(N: StartIdx);
573 if (!R.isZero()) {
574 SimpVect.push_back(Elt: &R);
575 }
576 }
577 }
578
579 assert((NextTmpIdx <= std::size(TmpResult) + 1) && "out-of-bound access");
580
581 Value *Result;
582 if (!SimpVect.empty())
583 Result = createNaryFAdd(Opnds: SimpVect, InstrQuota);
584 else {
585 // The addition is folded to 0.0.
586 Result = ConstantFP::get(Ty: Instr->getType(), V: 0.0);
587 }
588
589 return Result;
590}
591
592Value *FAddCombine::createNaryFAdd
593 (const AddendVect &Opnds, unsigned InstrQuota) {
594 assert(!Opnds.empty() && "Expect at least one addend");
595
596 // Step 1: Check if the # of instructions needed exceeds the quota.
597
598 unsigned InstrNeeded = calcInstrNumber(Vect: Opnds);
599 if (InstrNeeded > InstrQuota)
600 return nullptr;
601
602 initCreateInstNum();
603
604 // step 2: Emit the N-ary addition.
605 // Note that at most three instructions are involved in Fadd-InstCombine: the
606 // addition in question, and at most two neighboring instructions.
607 // The resulting optimized addition should have at least one less instruction
608 // than the original addition expression tree. This implies that the resulting
609 // N-ary addition has at most two instructions, and we don't need to worry
610 // about tree-height when constructing the N-ary addition.
611
612 Value *LastVal = nullptr;
613 bool LastValNeedNeg = false;
614
615 // Iterate the addends, creating fadd/fsub using adjacent two addends.
616 for (const FAddend *Opnd : Opnds) {
617 bool NeedNeg;
618 Value *V = createAddendVal(A: *Opnd, NeedNeg);
619 if (!LastVal) {
620 LastVal = V;
621 LastValNeedNeg = NeedNeg;
622 continue;
623 }
624
625 if (LastValNeedNeg == NeedNeg) {
626 LastVal = createFAdd(Opnd0: LastVal, Opnd1: V);
627 continue;
628 }
629
630 if (LastValNeedNeg)
631 LastVal = createFSub(Opnd0: V, Opnd1: LastVal);
632 else
633 LastVal = createFSub(Opnd0: LastVal, Opnd1: V);
634
635 LastValNeedNeg = false;
636 }
637
638 if (LastValNeedNeg) {
639 LastVal = createFNeg(V: LastVal);
640 }
641
642#ifndef NDEBUG
643 assert(CreateInstrNum == InstrNeeded &&
644 "Inconsistent in instruction numbers");
645#endif
646
647 return LastVal;
648}
649
650Value *FAddCombine::createFSub(Value *Opnd0, Value *Opnd1) {
651 Value *V = Builder.CreateFSub(L: Opnd0, R: Opnd1);
652 if (Instruction *I = dyn_cast<Instruction>(Val: V))
653 createInstPostProc(NewInst: I);
654 return V;
655}
656
657Value *FAddCombine::createFNeg(Value *V) {
658 Value *NewV = Builder.CreateFNeg(V);
659 if (Instruction *I = dyn_cast<Instruction>(Val: NewV))
660 createInstPostProc(NewInst: I, NoNumber: true); // fneg's don't receive instruction numbers.
661 return NewV;
662}
663
664Value *FAddCombine::createFAdd(Value *Opnd0, Value *Opnd1) {
665 Value *V = Builder.CreateFAdd(L: Opnd0, R: Opnd1);
666 if (Instruction *I = dyn_cast<Instruction>(Val: V))
667 createInstPostProc(NewInst: I);
668 return V;
669}
670
671Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
672 Value *V = Builder.CreateFMul(L: Opnd0, R: Opnd1);
673 if (Instruction *I = dyn_cast<Instruction>(Val: V))
674 createInstPostProc(NewInst: I);
675 return V;
676}
677
678void FAddCombine::createInstPostProc(Instruction *NewInstr, bool NoNumber) {
679 NewInstr->setDebugLoc(Instr->getDebugLoc());
680
681 // Keep track of the number of instruction created.
682 if (!NoNumber)
683 incCreateInstNum();
684
685 // Propagate fast-math flags
686 NewInstr->setFastMathFlags(Instr->getFastMathFlags());
687}
688
689// Return the number of instruction needed to emit the N-ary addition.
690// NOTE: Keep this function in sync with createAddendVal().
691unsigned FAddCombine::calcInstrNumber(const AddendVect &Opnds) {
692 unsigned OpndNum = Opnds.size();
693 unsigned InstrNeeded = OpndNum - 1;
694
695 // Adjust the number of instructions needed to emit the N-ary add.
696 for (const FAddend *Opnd : Opnds) {
697 if (Opnd->isConstant())
698 continue;
699
700 // The constant check above is really for a few special constant
701 // coefficients.
702 if (isa<UndefValue>(Val: Opnd->getSymVal()))
703 continue;
704
705 const FAddendCoef &CE = Opnd->getCoef();
706 // Let the addend be "c * x". If "c == +/-1", the value of the addend
707 // is immediately available; otherwise, it needs exactly one instruction
708 // to evaluate the value.
709 if (!CE.isMinusOne() && !CE.isOne())
710 InstrNeeded++;
711 }
712 return InstrNeeded;
713}
714
715// Input Addend Value NeedNeg(output)
716// ================================================================
717// Constant C C false
718// <+/-1, V> V coefficient is -1
719// <2/-2, V> "fadd V, V" coefficient is -2
720// <C, V> "fmul V, C" false
721//
722// NOTE: Keep this function in sync with FAddCombine::calcInstrNumber.
723Value *FAddCombine::createAddendVal(const FAddend &Opnd, bool &NeedNeg) {
724 const FAddendCoef &Coeff = Opnd.getCoef();
725
726 if (Opnd.isConstant()) {
727 NeedNeg = false;
728 return Coeff.getValue(Ty: Instr->getType());
729 }
730
731 Value *OpndVal = Opnd.getSymVal();
732
733 if (Coeff.isMinusOne() || Coeff.isOne()) {
734 NeedNeg = Coeff.isMinusOne();
735 return OpndVal;
736 }
737
738 if (Coeff.isTwo() || Coeff.isMinusTwo()) {
739 NeedNeg = Coeff.isMinusTwo();
740 return createFAdd(Opnd0: OpndVal, Opnd1: OpndVal);
741 }
742
743 NeedNeg = false;
744 return createFMul(Opnd0: OpndVal, Opnd1: Coeff.getValue(Ty: Instr->getType()));
745}
746
747// Checks if any operand is negative and we can convert add to sub.
748// This function checks for following negative patterns
749// ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C))
750// ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C))
751// XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even
752static Value *checkForNegativeOperand(BinaryOperator &I,
753 InstCombiner::BuilderTy &Builder) {
754 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
755
756 // This function creates 2 instructions to replace ADD, we need at least one
757 // of LHS or RHS to have one use to ensure benefit in transform.
758 if (!LHS->hasOneUse() && !RHS->hasOneUse())
759 return nullptr;
760
761 Value *X = nullptr, *Y = nullptr, *Z = nullptr;
762 const APInt *C1 = nullptr, *C2 = nullptr;
763
764 // if ONE is on other side, swap
765 if (match(V: RHS, P: m_Add(L: m_Value(V&: X), R: m_One())))
766 std::swap(a&: LHS, b&: RHS);
767
768 if (match(V: LHS, P: m_Add(L: m_Value(V&: X), R: m_One()))) {
769 // if XOR on other side, swap
770 if (match(V: RHS, P: m_Xor(L: m_Value(V&: Y), R: m_APInt(Res&: C1))))
771 std::swap(a&: X, b&: RHS);
772
773 if (match(V: X, P: m_Xor(L: m_Value(V&: Y), R: m_APInt(Res&: C1)))) {
774 // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1))
775 // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1))
776 if (match(V: Y, P: m_Or(L: m_Value(V&: Z), R: m_APInt(Res&: C2))) && (*C2 == ~(*C1))) {
777 Value *NewAnd = Builder.CreateAnd(LHS: Z, RHS: *C1);
778 return Builder.CreateSub(LHS: RHS, RHS: NewAnd, Name: "sub");
779 } else if (match(V: Y, P: m_And(L: m_Value(V&: Z), R: m_APInt(Res&: C2))) && (*C1 == *C2)) {
780 // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1))
781 // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1))
782 Value *NewOr = Builder.CreateOr(LHS: Z, RHS: ~(*C1));
783 return Builder.CreateSub(LHS: RHS, RHS: NewOr, Name: "sub");
784 }
785 }
786 }
787
788 // Restore LHS and RHS
789 LHS = I.getOperand(i_nocapture: 0);
790 RHS = I.getOperand(i_nocapture: 1);
791
792 // if XOR is on other side, swap
793 if (match(V: RHS, P: m_Xor(L: m_Value(V&: Y), R: m_APInt(Res&: C1))))
794 std::swap(a&: LHS, b&: RHS);
795
796 // C2 is ODD
797 // LHS = XOR(Y, C1), Y = AND(Z, C2), C1 == (C2 + 1) => LHS == NEG(OR(Z, ~C2))
798 // ADD(LHS, RHS) == SUB(RHS, OR(Z, ~C2))
799 if (match(V: LHS, P: m_Xor(L: m_Value(V&: Y), R: m_APInt(Res&: C1))))
800 if (C1->countr_zero() == 0)
801 if (match(V: Y, P: m_And(L: m_Value(V&: Z), R: m_APInt(Res&: C2))) && *C1 == (*C2 + 1)) {
802 Value *NewOr = Builder.CreateOr(LHS: Z, RHS: ~(*C2));
803 return Builder.CreateSub(LHS: RHS, RHS: NewOr, Name: "sub");
804 }
805 return nullptr;
806}
807
808/// Wrapping flags may allow combining constants separated by an extend.
809static Instruction *foldNoWrapAdd(BinaryOperator &Add,
810 InstCombiner::BuilderTy &Builder) {
811 Value *Op0 = Add.getOperand(i_nocapture: 0), *Op1 = Add.getOperand(i_nocapture: 1);
812 Type *Ty = Add.getType();
813 Constant *Op1C;
814 if (!match(V: Op1, P: m_Constant(C&: Op1C)))
815 return nullptr;
816
817 // Try this match first because it results in an add in the narrow type.
818 // (zext (X +nuw C2)) + C1 --> zext (X + (C2 + trunc(C1)))
819 Value *X;
820 const APInt *C1, *C2;
821 if (match(V: Op1, P: m_APInt(Res&: C1)) &&
822 match(V: Op0, P: m_ZExt(Op: m_NUWAddLike(L: m_Value(V&: X), R: m_APInt(Res&: C2)))) &&
823 C1->isNegative() && C1->sge(RHS: -C2->sext(width: C1->getBitWidth()))) {
824 APInt NewC = *C2 + C1->trunc(width: C2->getBitWidth());
825 // If the smaller add will fold to zero, we don't need to check one use.
826 if (NewC.isZero())
827 return new ZExtInst(X, Ty);
828 // Otherwise only do this if the existing zero extend will be removed.
829 if (Op0->hasOneUse())
830 return new ZExtInst(
831 Builder.CreateNUWAdd(LHS: X, RHS: ConstantInt::get(Ty: X->getType(), V: NewC)), Ty);
832 }
833
834 // More general combining of constants in the wide type.
835 // (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
836 // or (zext nneg (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
837 Constant *NarrowC;
838 if (match(V: Op0, P: m_OneUse(SubPattern: m_SExtLike(
839 Op: m_NSWAddLike(L: m_Value(V&: X), R: m_Constant(C&: NarrowC)))))) {
840 Value *WideC = Builder.CreateSExt(V: NarrowC, DestTy: Ty);
841 Value *NewC = Builder.CreateAdd(LHS: WideC, RHS: Op1C);
842 Value *WideX = Builder.CreateSExt(V: X, DestTy: Ty);
843 return BinaryOperator::CreateAdd(V1: WideX, V2: NewC);
844 }
845 // (zext (X +nuw NarrowC)) + C --> (zext X) + (zext(NarrowC) + C)
846 if (match(V: Op0,
847 P: m_OneUse(SubPattern: m_ZExt(Op: m_NUWAddLike(L: m_Value(V&: X), R: m_Constant(C&: NarrowC)))))) {
848 Value *WideC = Builder.CreateZExt(V: NarrowC, DestTy: Ty);
849 Value *NewC = Builder.CreateAdd(LHS: WideC, RHS: Op1C);
850 Value *WideX = Builder.CreateZExt(V: X, DestTy: Ty);
851 return BinaryOperator::CreateAdd(V1: WideX, V2: NewC);
852 }
853 return nullptr;
854}
855
856Instruction *InstCombinerImpl::foldAddWithConstant(BinaryOperator &Add) {
857 Value *Op0 = Add.getOperand(i_nocapture: 0), *Op1 = Add.getOperand(i_nocapture: 1);
858 Type *Ty = Add.getType();
859 Constant *Op1C;
860 if (!match(V: Op1, P: m_ImmConstant(C&: Op1C)))
861 return nullptr;
862
863 if (Instruction *NV = foldBinOpIntoSelectOrPhi(I&: Add))
864 return NV;
865
866 Value *X;
867 Constant *Op00C;
868
869 // add (sub C1, X), C2 --> sub (add C1, C2), X
870 if (match(V: Op0, P: m_Sub(L: m_Constant(C&: Op00C), R: m_Value(V&: X))))
871 return BinaryOperator::CreateSub(V1: ConstantExpr::getAdd(C1: Op00C, C2: Op1C), V2: X);
872
873 Value *Y;
874
875 // add (sub X, Y), -1 --> add (not Y), X
876 if (match(V: Op0, P: m_OneUse(SubPattern: m_Sub(L: m_Value(V&: X), R: m_Value(V&: Y)))) &&
877 match(V: Op1, P: m_AllOnes()))
878 return BinaryOperator::CreateAdd(V1: Builder.CreateNot(V: Y), V2: X);
879
880 // zext(bool) + C -> bool ? C + 1 : C
881 if (match(V: Op0, P: m_ZExt(Op: m_Value(V&: X))) &&
882 X->getType()->getScalarSizeInBits() == 1)
883 return SelectInst::Create(C: X, S1: InstCombiner::AddOne(C: Op1C), S2: Op1);
884 // sext(bool) + C -> bool ? C - 1 : C
885 if (match(V: Op0, P: m_SExt(Op: m_Value(V&: X))) &&
886 X->getType()->getScalarSizeInBits() == 1)
887 return SelectInst::Create(C: X, S1: InstCombiner::SubOne(C: Op1C), S2: Op1);
888
889 // ~X + C --> (C-1) - X
890 if (match(V: Op0, P: m_Not(V: m_Value(V&: X)))) {
891 // ~X + C has NSW and (C-1) won't oveflow => (C-1)-X can have NSW
892 auto *COne = ConstantInt::get(Ty: Op1C->getType(), V: 1);
893 bool WillNotSOV = willNotOverflowSignedSub(LHS: Op1C, RHS: COne, CxtI: Add);
894 BinaryOperator *Res =
895 BinaryOperator::CreateSub(V1: ConstantExpr::getSub(C1: Op1C, C2: COne), V2: X);
896 Res->setHasNoSignedWrap(Add.hasNoSignedWrap() && WillNotSOV);
897 return Res;
898 }
899
900 // (iN X s>> (N - 1)) + 1 --> zext (X > -1)
901 const APInt *C;
902 unsigned BitWidth = Ty->getScalarSizeInBits();
903 if (match(V: Op0, P: m_OneUse(SubPattern: m_AShr(L: m_Value(V&: X),
904 R: m_SpecificIntAllowPoison(V: BitWidth - 1)))) &&
905 match(V: Op1, P: m_One()))
906 return new ZExtInst(Builder.CreateIsNotNeg(Arg: X, Name: "isnotneg"), Ty);
907
908 if (!match(V: Op1, P: m_APInt(Res&: C)))
909 return nullptr;
910
911 // (X | Op01C) + Op1C --> X + (Op01C + Op1C) iff the `or` is actually an `add`
912 Constant *Op01C;
913 if (match(V: Op0, P: m_DisjointOr(L: m_Value(V&: X), R: m_ImmConstant(C&: Op01C)))) {
914 BinaryOperator *NewAdd =
915 BinaryOperator::CreateAdd(V1: X, V2: ConstantExpr::getAdd(C1: Op01C, C2: Op1C));
916 NewAdd->setHasNoSignedWrap(Add.hasNoSignedWrap() &&
917 willNotOverflowSignedAdd(LHS: Op01C, RHS: Op1C, CxtI: Add));
918 NewAdd->setHasNoUnsignedWrap(Add.hasNoUnsignedWrap());
919 return NewAdd;
920 }
921
922 // (X | C2) + C --> (X | C2) ^ C2 iff (C2 == -C)
923 const APInt *C2;
924 if (match(V: Op0, P: m_Or(L: m_Value(), R: m_APInt(Res&: C2))) && *C2 == -*C)
925 return BinaryOperator::CreateXor(V1: Op0, V2: ConstantInt::get(Ty: Add.getType(), V: *C2));
926
927 if (C->isSignMask()) {
928 // If wrapping is not allowed, then the addition must set the sign bit:
929 // X + (signmask) --> X | signmask
930 if (Add.hasNoSignedWrap() || Add.hasNoUnsignedWrap())
931 return BinaryOperator::CreateOr(V1: Op0, V2: Op1);
932
933 // If wrapping is allowed, then the addition flips the sign bit of LHS:
934 // X + (signmask) --> X ^ signmask
935 return BinaryOperator::CreateXor(V1: Op0, V2: Op1);
936 }
937
938 // Is this add the last step in a convoluted sext?
939 // add(zext(xor i16 X, -32768), -32768) --> sext X
940 if (match(V: Op0, P: m_ZExt(Op: m_Xor(L: m_Value(V&: X), R: m_APInt(Res&: C2)))) &&
941 C2->isMinSignedValue() && C2->sext(width: Ty->getScalarSizeInBits()) == *C)
942 return CastInst::Create(Instruction::SExt, S: X, Ty);
943
944 if (match(V: Op0, P: m_Xor(L: m_Value(V&: X), R: m_APInt(Res&: C2)))) {
945 // (X ^ signmask) + C --> (X + (signmask ^ C))
946 if (C2->isSignMask())
947 return BinaryOperator::CreateAdd(V1: X, V2: ConstantInt::get(Ty, V: *C2 ^ *C));
948
949 // If X has no high-bits set above an xor mask:
950 // add (xor X, LowMaskC), C --> sub (LowMaskC + C), X
951 if (C2->isMask()) {
952 KnownBits LHSKnown = computeKnownBits(V: X, Depth: 0, CxtI: &Add);
953 if ((*C2 | LHSKnown.Zero).isAllOnes())
954 return BinaryOperator::CreateSub(V1: ConstantInt::get(Ty, V: *C2 + *C), V2: X);
955 }
956
957 // Look for a math+logic pattern that corresponds to sext-in-register of a
958 // value with cleared high bits. Convert that into a pair of shifts:
959 // add (xor X, 0x80), 0xF..F80 --> (X << ShAmtC) >>s ShAmtC
960 // add (xor X, 0xF..F80), 0x80 --> (X << ShAmtC) >>s ShAmtC
961 if (Op0->hasOneUse() && *C2 == -(*C)) {
962 unsigned BitWidth = Ty->getScalarSizeInBits();
963 unsigned ShAmt = 0;
964 if (C->isPowerOf2())
965 ShAmt = BitWidth - C->logBase2() - 1;
966 else if (C2->isPowerOf2())
967 ShAmt = BitWidth - C2->logBase2() - 1;
968 if (ShAmt && MaskedValueIsZero(V: X, Mask: APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: ShAmt),
969 Depth: 0, CxtI: &Add)) {
970 Constant *ShAmtC = ConstantInt::get(Ty, V: ShAmt);
971 Value *NewShl = Builder.CreateShl(LHS: X, RHS: ShAmtC, Name: "sext");
972 return BinaryOperator::CreateAShr(V1: NewShl, V2: ShAmtC);
973 }
974 }
975 }
976
977 if (C->isOne() && Op0->hasOneUse()) {
978 // add (sext i1 X), 1 --> zext (not X)
979 // TODO: The smallest IR representation is (select X, 0, 1), and that would
980 // not require the one-use check. But we need to remove a transform in
981 // visitSelect and make sure that IR value tracking for select is equal or
982 // better than for these ops.
983 if (match(V: Op0, P: m_SExt(Op: m_Value(V&: X))) &&
984 X->getType()->getScalarSizeInBits() == 1)
985 return new ZExtInst(Builder.CreateNot(V: X), Ty);
986
987 // Shifts and add used to flip and mask off the low bit:
988 // add (ashr (shl i32 X, 31), 31), 1 --> and (not X), 1
989 const APInt *C3;
990 if (match(V: Op0, P: m_AShr(L: m_Shl(L: m_Value(V&: X), R: m_APInt(Res&: C2)), R: m_APInt(Res&: C3))) &&
991 C2 == C3 && *C2 == Ty->getScalarSizeInBits() - 1) {
992 Value *NotX = Builder.CreateNot(V: X);
993 return BinaryOperator::CreateAnd(V1: NotX, V2: ConstantInt::get(Ty, V: 1));
994 }
995 }
996
997 // Fold (add (zext (add X, -1)), 1) -> (zext X) if X is non-zero.
998 // TODO: There's a general form for any constant on the outer add.
999 if (C->isOne()) {
1000 if (match(V: Op0, P: m_ZExt(Op: m_Add(L: m_Value(V&: X), R: m_AllOnes())))) {
1001 const SimplifyQuery Q = SQ.getWithInstruction(I: &Add);
1002 if (llvm::isKnownNonZero(V: X, Q))
1003 return new ZExtInst(X, Ty);
1004 }
1005 }
1006
1007 return nullptr;
1008}
1009
1010// match variations of a^2 + 2*a*b + b^2
1011//
1012// to reuse the code between the FP and Int versions, the instruction OpCodes
1013// and constant types have been turned into template parameters.
1014//
1015// Mul2Rhs: The constant to perform the multiplicative equivalent of X*2 with;
1016// should be `m_SpecificFP(2.0)` for FP and `m_SpecificInt(1)` for Int
1017// (we're matching `X<<1` instead of `X*2` for Int)
1018template <bool FP, typename Mul2Rhs>
1019static bool matchesSquareSum(BinaryOperator &I, Mul2Rhs M2Rhs, Value *&A,
1020 Value *&B) {
1021 constexpr unsigned MulOp = FP ? Instruction::FMul : Instruction::Mul;
1022 constexpr unsigned AddOp = FP ? Instruction::FAdd : Instruction::Add;
1023 constexpr unsigned Mul2Op = FP ? Instruction::FMul : Instruction::Shl;
1024
1025 // (a * a) + (((a * 2) + b) * b)
1026 if (match(&I, m_c_BinOp(
1027 AddOp, m_OneUse(SubPattern: m_BinOp(Opcode: MulOp, L: m_Value(V&: A), R: m_Deferred(V: A))),
1028 m_OneUse(m_c_BinOp(
1029 MulOp,
1030 m_c_BinOp(AddOp, m_BinOp(Mul2Op, m_Deferred(V: A), M2Rhs),
1031 m_Value(V&: B)),
1032 m_Deferred(V: B))))))
1033 return true;
1034
1035 // ((a * b) * 2) or ((a * 2) * b)
1036 // +
1037 // (a * a + b * b) or (b * b + a * a)
1038 return match(
1039 &I, m_c_BinOp(
1040 AddOp,
1041 m_CombineOr(
1042 m_OneUse(m_BinOp(
1043 Mul2Op, m_BinOp(Opcode: MulOp, L: m_Value(V&: A), R: m_Value(V&: B)), M2Rhs)),
1044 m_OneUse(m_c_BinOp(MulOp, m_BinOp(Mul2Op, m_Value(V&: A), M2Rhs),
1045 m_Value(V&: B)))),
1046 m_OneUse(
1047 SubPattern: m_c_BinOp(Opcode: AddOp, L: m_BinOp(Opcode: MulOp, L: m_Deferred(V: A), R: m_Deferred(V: A)),
1048 R: m_BinOp(Opcode: MulOp, L: m_Deferred(V: B), R: m_Deferred(V: B))))));
1049}
1050
1051// Fold integer variations of a^2 + 2*a*b + b^2 -> (a + b)^2
1052Instruction *InstCombinerImpl::foldSquareSumInt(BinaryOperator &I) {
1053 Value *A, *B;
1054 if (matchesSquareSum</*FP*/ false>(I, M2Rhs: m_SpecificInt(V: 1), A, B)) {
1055 Value *AB = Builder.CreateAdd(LHS: A, RHS: B);
1056 return BinaryOperator::CreateMul(V1: AB, V2: AB);
1057 }
1058 return nullptr;
1059}
1060
1061// Fold floating point variations of a^2 + 2*a*b + b^2 -> (a + b)^2
1062// Requires `nsz` and `reassoc`.
1063Instruction *InstCombinerImpl::foldSquareSumFP(BinaryOperator &I) {
1064 assert(I.hasAllowReassoc() && I.hasNoSignedZeros() && "Assumption mismatch");
1065 Value *A, *B;
1066 if (matchesSquareSum</*FP*/ true>(I, M2Rhs: m_SpecificFP(V: 2.0), A, B)) {
1067 Value *AB = Builder.CreateFAddFMF(L: A, R: B, FMFSource: &I);
1068 return BinaryOperator::CreateFMulFMF(V1: AB, V2: AB, FMFSource: &I);
1069 }
1070 return nullptr;
1071}
1072
1073// Matches multiplication expression Op * C where C is a constant. Returns the
1074// constant value in C and the other operand in Op. Returns true if such a
1075// match is found.
1076static bool MatchMul(Value *E, Value *&Op, APInt &C) {
1077 const APInt *AI;
1078 if (match(V: E, P: m_Mul(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1079 C = *AI;
1080 return true;
1081 }
1082 if (match(V: E, P: m_Shl(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1083 C = APInt(AI->getBitWidth(), 1);
1084 C <<= *AI;
1085 return true;
1086 }
1087 return false;
1088}
1089
1090// Matches remainder expression Op % C where C is a constant. Returns the
1091// constant value in C and the other operand in Op. Returns the signedness of
1092// the remainder operation in IsSigned. Returns true if such a match is
1093// found.
1094static bool MatchRem(Value *E, Value *&Op, APInt &C, bool &IsSigned) {
1095 const APInt *AI;
1096 IsSigned = false;
1097 if (match(V: E, P: m_SRem(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1098 IsSigned = true;
1099 C = *AI;
1100 return true;
1101 }
1102 if (match(V: E, P: m_URem(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1103 C = *AI;
1104 return true;
1105 }
1106 if (match(V: E, P: m_And(L: m_Value(V&: Op), R: m_APInt(Res&: AI))) && (*AI + 1).isPowerOf2()) {
1107 C = *AI + 1;
1108 return true;
1109 }
1110 return false;
1111}
1112
1113// Matches division expression Op / C with the given signedness as indicated
1114// by IsSigned, where C is a constant. Returns the constant value in C and the
1115// other operand in Op. Returns true if such a match is found.
1116static bool MatchDiv(Value *E, Value *&Op, APInt &C, bool IsSigned) {
1117 const APInt *AI;
1118 if (IsSigned && match(V: E, P: m_SDiv(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1119 C = *AI;
1120 return true;
1121 }
1122 if (!IsSigned) {
1123 if (match(V: E, P: m_UDiv(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1124 C = *AI;
1125 return true;
1126 }
1127 if (match(V: E, P: m_LShr(L: m_Value(V&: Op), R: m_APInt(Res&: AI)))) {
1128 C = APInt(AI->getBitWidth(), 1);
1129 C <<= *AI;
1130 return true;
1131 }
1132 }
1133 return false;
1134}
1135
1136// Returns whether C0 * C1 with the given signedness overflows.
1137static bool MulWillOverflow(APInt &C0, APInt &C1, bool IsSigned) {
1138 bool overflow;
1139 if (IsSigned)
1140 (void)C0.smul_ov(RHS: C1, Overflow&: overflow);
1141 else
1142 (void)C0.umul_ov(RHS: C1, Overflow&: overflow);
1143 return overflow;
1144}
1145
1146// Simplifies X % C0 + (( X / C0 ) % C1) * C0 to X % (C0 * C1), where (C0 * C1)
1147// does not overflow.
1148// Simplifies (X / C0) * C1 + (X % C0) * C2 to
1149// (X / C0) * (C1 - C2 * C0) + X * C2
1150Value *InstCombinerImpl::SimplifyAddWithRemainder(BinaryOperator &I) {
1151 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1152 Value *X, *MulOpV;
1153 APInt C0, MulOpC;
1154 bool IsSigned;
1155 // Match I = X % C0 + MulOpV * C0
1156 if (((MatchRem(E: LHS, Op&: X, C&: C0, IsSigned) && MatchMul(E: RHS, Op&: MulOpV, C&: MulOpC)) ||
1157 (MatchRem(E: RHS, Op&: X, C&: C0, IsSigned) && MatchMul(E: LHS, Op&: MulOpV, C&: MulOpC))) &&
1158 C0 == MulOpC) {
1159 Value *RemOpV;
1160 APInt C1;
1161 bool Rem2IsSigned;
1162 // Match MulOpC = RemOpV % C1
1163 if (MatchRem(E: MulOpV, Op&: RemOpV, C&: C1, IsSigned&: Rem2IsSigned) &&
1164 IsSigned == Rem2IsSigned) {
1165 Value *DivOpV;
1166 APInt DivOpC;
1167 // Match RemOpV = X / C0
1168 if (MatchDiv(E: RemOpV, Op&: DivOpV, C&: DivOpC, IsSigned) && X == DivOpV &&
1169 C0 == DivOpC && !MulWillOverflow(C0, C1, IsSigned)) {
1170 Value *NewDivisor = ConstantInt::get(Ty: X->getType(), V: C0 * C1);
1171 return IsSigned ? Builder.CreateSRem(LHS: X, RHS: NewDivisor, Name: "srem")
1172 : Builder.CreateURem(LHS: X, RHS: NewDivisor, Name: "urem");
1173 }
1174 }
1175 }
1176
1177 // Match I = (X / C0) * C1 + (X % C0) * C2
1178 Value *Div, *Rem;
1179 APInt C1, C2;
1180 if (!LHS->hasOneUse() || !MatchMul(E: LHS, Op&: Div, C&: C1))
1181 Div = LHS, C1 = APInt(I.getType()->getScalarSizeInBits(), 1);
1182 if (!RHS->hasOneUse() || !MatchMul(E: RHS, Op&: Rem, C&: C2))
1183 Rem = RHS, C2 = APInt(I.getType()->getScalarSizeInBits(), 1);
1184 if (match(V: Div, P: m_IRem(L: m_Value(), R: m_Value()))) {
1185 std::swap(a&: Div, b&: Rem);
1186 std::swap(a&: C1, b&: C2);
1187 }
1188 Value *DivOpV;
1189 APInt DivOpC;
1190 if (MatchRem(E: Rem, Op&: X, C&: C0, IsSigned) &&
1191 MatchDiv(E: Div, Op&: DivOpV, C&: DivOpC, IsSigned) && X == DivOpV && C0 == DivOpC) {
1192 APInt NewC = C1 - C2 * C0;
1193 if (!NewC.isZero() && !Rem->hasOneUse())
1194 return nullptr;
1195 if (!isGuaranteedNotToBeUndef(V: X, AC: &AC, CtxI: &I, DT: &DT))
1196 return nullptr;
1197 Value *MulXC2 = Builder.CreateMul(LHS: X, RHS: ConstantInt::get(Ty: X->getType(), V: C2));
1198 if (NewC.isZero())
1199 return MulXC2;
1200 return Builder.CreateAdd(
1201 LHS: Builder.CreateMul(LHS: Div, RHS: ConstantInt::get(Ty: X->getType(), V: NewC)), RHS: MulXC2);
1202 }
1203
1204 return nullptr;
1205}
1206
1207/// Fold
1208/// (1 << NBits) - 1
1209/// Into:
1210/// ~(-(1 << NBits))
1211/// Because a 'not' is better for bit-tracking analysis and other transforms
1212/// than an 'add'. The new shl is always nsw, and is nuw if old `and` was.
1213static Instruction *canonicalizeLowbitMask(BinaryOperator &I,
1214 InstCombiner::BuilderTy &Builder) {
1215 Value *NBits;
1216 if (!match(V: &I, P: m_Add(L: m_OneUse(SubPattern: m_Shl(L: m_One(), R: m_Value(V&: NBits))), R: m_AllOnes())))
1217 return nullptr;
1218
1219 Constant *MinusOne = Constant::getAllOnesValue(Ty: NBits->getType());
1220 Value *NotMask = Builder.CreateShl(LHS: MinusOne, RHS: NBits, Name: "notmask");
1221 // Be wary of constant folding.
1222 if (auto *BOp = dyn_cast<BinaryOperator>(Val: NotMask)) {
1223 // Always NSW. But NUW propagates from `add`.
1224 BOp->setHasNoSignedWrap();
1225 BOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1226 }
1227
1228 return BinaryOperator::CreateNot(Op: NotMask, Name: I.getName());
1229}
1230
1231static Instruction *foldToUnsignedSaturatedAdd(BinaryOperator &I) {
1232 assert(I.getOpcode() == Instruction::Add && "Expecting add instruction");
1233 Type *Ty = I.getType();
1234 auto getUAddSat = [&]() {
1235 return Intrinsic::getDeclaration(M: I.getModule(), id: Intrinsic::uadd_sat, Tys: Ty);
1236 };
1237
1238 // add (umin X, ~Y), Y --> uaddsat X, Y
1239 Value *X, *Y;
1240 if (match(V: &I, P: m_c_Add(L: m_c_UMin(L: m_Value(V&: X), R: m_Not(V: m_Value(V&: Y))),
1241 R: m_Deferred(V: Y))))
1242 return CallInst::Create(Func: getUAddSat(), Args: { X, Y });
1243
1244 // add (umin X, ~C), C --> uaddsat X, C
1245 const APInt *C, *NotC;
1246 if (match(V: &I, P: m_Add(L: m_UMin(L: m_Value(V&: X), R: m_APInt(Res&: NotC)), R: m_APInt(Res&: C))) &&
1247 *C == ~*NotC)
1248 return CallInst::Create(Func: getUAddSat(), Args: { X, ConstantInt::get(Ty, V: *C) });
1249
1250 return nullptr;
1251}
1252
1253// Transform:
1254// (add A, (shl (neg B), Y))
1255// -> (sub A, (shl B, Y))
1256static Instruction *combineAddSubWithShlAddSub(InstCombiner::BuilderTy &Builder,
1257 const BinaryOperator &I) {
1258 Value *A, *B, *Cnt;
1259 if (match(V: &I,
1260 P: m_c_Add(L: m_OneUse(SubPattern: m_Shl(L: m_OneUse(SubPattern: m_Neg(V: m_Value(V&: B))), R: m_Value(V&: Cnt))),
1261 R: m_Value(V&: A)))) {
1262 Value *NewShl = Builder.CreateShl(LHS: B, RHS: Cnt);
1263 return BinaryOperator::CreateSub(V1: A, V2: NewShl);
1264 }
1265 return nullptr;
1266}
1267
1268/// Try to reduce signed division by power-of-2 to an arithmetic shift right.
1269static Instruction *foldAddToAshr(BinaryOperator &Add) {
1270 // Division must be by power-of-2, but not the minimum signed value.
1271 Value *X;
1272 const APInt *DivC;
1273 if (!match(V: Add.getOperand(i_nocapture: 0), P: m_SDiv(L: m_Value(V&: X), R: m_Power2(V&: DivC))) ||
1274 DivC->isNegative())
1275 return nullptr;
1276
1277 // Rounding is done by adding -1 if the dividend (X) is negative and has any
1278 // low bits set. It recognizes two canonical patterns:
1279 // 1. For an 'ugt' cmp with the signed minimum value (SMIN), the
1280 // pattern is: sext (icmp ugt (X & (DivC - 1)), SMIN).
1281 // 2. For an 'eq' cmp, the pattern's: sext (icmp eq X & (SMIN + 1), SMIN + 1).
1282 // Note that, by the time we end up here, if possible, ugt has been
1283 // canonicalized into eq.
1284 const APInt *MaskC, *MaskCCmp;
1285 ICmpInst::Predicate Pred;
1286 if (!match(V: Add.getOperand(i_nocapture: 1),
1287 P: m_SExt(Op: m_ICmp(Pred, L: m_And(L: m_Specific(V: X), R: m_APInt(Res&: MaskC)),
1288 R: m_APInt(Res&: MaskCCmp)))))
1289 return nullptr;
1290
1291 if ((Pred != ICmpInst::ICMP_UGT || !MaskCCmp->isSignMask()) &&
1292 (Pred != ICmpInst::ICMP_EQ || *MaskCCmp != *MaskC))
1293 return nullptr;
1294
1295 APInt SMin = APInt::getSignedMinValue(numBits: Add.getType()->getScalarSizeInBits());
1296 bool IsMaskValid = Pred == ICmpInst::ICMP_UGT
1297 ? (*MaskC == (SMin | (*DivC - 1)))
1298 : (*DivC == 2 && *MaskC == SMin + 1);
1299 if (!IsMaskValid)
1300 return nullptr;
1301
1302 // (X / DivC) + sext ((X & (SMin | (DivC - 1)) >u SMin) --> X >>s log2(DivC)
1303 return BinaryOperator::CreateAShr(
1304 V1: X, V2: ConstantInt::get(Ty: Add.getType(), V: DivC->exactLogBase2()));
1305}
1306
1307Instruction *InstCombinerImpl::
1308 canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(
1309 BinaryOperator &I) {
1310 assert((I.getOpcode() == Instruction::Add ||
1311 I.getOpcode() == Instruction::Or ||
1312 I.getOpcode() == Instruction::Sub) &&
1313 "Expecting add/or/sub instruction");
1314
1315 // We have a subtraction/addition between a (potentially truncated) *logical*
1316 // right-shift of X and a "select".
1317 Value *X, *Select;
1318 Instruction *LowBitsToSkip, *Extract;
1319 if (!match(V: &I, P: m_c_BinOp(L: m_TruncOrSelf(Op: m_CombineAnd(
1320 L: m_LShr(L: m_Value(V&: X), R: m_Instruction(I&: LowBitsToSkip)),
1321 R: m_Instruction(I&: Extract))),
1322 R: m_Value(V&: Select))))
1323 return nullptr;
1324
1325 // `add`/`or` is commutative; but for `sub`, "select" *must* be on RHS.
1326 if (I.getOpcode() == Instruction::Sub && I.getOperand(i_nocapture: 1) != Select)
1327 return nullptr;
1328
1329 Type *XTy = X->getType();
1330 bool HadTrunc = I.getType() != XTy;
1331
1332 // If there was a truncation of extracted value, then we'll need to produce
1333 // one extra instruction, so we need to ensure one instruction will go away.
1334 if (HadTrunc && !match(V: &I, P: m_c_BinOp(L: m_OneUse(SubPattern: m_Value()), R: m_Value())))
1335 return nullptr;
1336
1337 // Extraction should extract high NBits bits, with shift amount calculated as:
1338 // low bits to skip = shift bitwidth - high bits to extract
1339 // The shift amount itself may be extended, and we need to look past zero-ext
1340 // when matching NBits, that will matter for matching later.
1341 Constant *C;
1342 Value *NBits;
1343 if (!match(
1344 V: LowBitsToSkip,
1345 P: m_ZExtOrSelf(Op: m_Sub(L: m_Constant(C), R: m_ZExtOrSelf(Op: m_Value(V&: NBits))))) ||
1346 !match(V: C, P: m_SpecificInt_ICMP(Predicate: ICmpInst::Predicate::ICMP_EQ,
1347 Threshold: APInt(C->getType()->getScalarSizeInBits(),
1348 X->getType()->getScalarSizeInBits()))))
1349 return nullptr;
1350
1351 // Sign-extending value can be zero-extended if we `sub`tract it,
1352 // or sign-extended otherwise.
1353 auto SkipExtInMagic = [&I](Value *&V) {
1354 if (I.getOpcode() == Instruction::Sub)
1355 match(V, P: m_ZExtOrSelf(Op: m_Value(V)));
1356 else
1357 match(V, P: m_SExtOrSelf(Op: m_Value(V)));
1358 };
1359
1360 // Now, finally validate the sign-extending magic.
1361 // `select` itself may be appropriately extended, look past that.
1362 SkipExtInMagic(Select);
1363
1364 ICmpInst::Predicate Pred;
1365 const APInt *Thr;
1366 Value *SignExtendingValue, *Zero;
1367 bool ShouldSignext;
1368 // It must be a select between two values we will later establish to be a
1369 // sign-extending value and a zero constant. The condition guarding the
1370 // sign-extension must be based on a sign bit of the same X we had in `lshr`.
1371 if (!match(V: Select, P: m_Select(C: m_ICmp(Pred, L: m_Specific(V: X), R: m_APInt(Res&: Thr)),
1372 L: m_Value(V&: SignExtendingValue), R: m_Value(V&: Zero))) ||
1373 !isSignBitCheck(Pred, RHS: *Thr, TrueIfSigned&: ShouldSignext))
1374 return nullptr;
1375
1376 // icmp-select pair is commutative.
1377 if (!ShouldSignext)
1378 std::swap(a&: SignExtendingValue, b&: Zero);
1379
1380 // If we should not perform sign-extension then we must add/or/subtract zero.
1381 if (!match(V: Zero, P: m_Zero()))
1382 return nullptr;
1383 // Otherwise, it should be some constant, left-shifted by the same NBits we
1384 // had in `lshr`. Said left-shift can also be appropriately extended.
1385 // Again, we must look past zero-ext when looking for NBits.
1386 SkipExtInMagic(SignExtendingValue);
1387 Constant *SignExtendingValueBaseConstant;
1388 if (!match(V: SignExtendingValue,
1389 P: m_Shl(L: m_Constant(C&: SignExtendingValueBaseConstant),
1390 R: m_ZExtOrSelf(Op: m_Specific(V: NBits)))))
1391 return nullptr;
1392 // If we `sub`, then the constant should be one, else it should be all-ones.
1393 if (I.getOpcode() == Instruction::Sub
1394 ? !match(V: SignExtendingValueBaseConstant, P: m_One())
1395 : !match(V: SignExtendingValueBaseConstant, P: m_AllOnes()))
1396 return nullptr;
1397
1398 auto *NewAShr = BinaryOperator::CreateAShr(V1: X, V2: LowBitsToSkip,
1399 Name: Extract->getName() + ".sext");
1400 NewAShr->copyIRFlags(V: Extract); // Preserve `exact`-ness.
1401 if (!HadTrunc)
1402 return NewAShr;
1403
1404 Builder.Insert(I: NewAShr);
1405 return TruncInst::CreateTruncOrBitCast(S: NewAShr, Ty: I.getType());
1406}
1407
1408/// This is a specialization of a more general transform from
1409/// foldUsingDistributiveLaws. If that code can be made to work optimally
1410/// for multi-use cases or propagating nsw/nuw, then we would not need this.
1411static Instruction *factorizeMathWithShlOps(BinaryOperator &I,
1412 InstCombiner::BuilderTy &Builder) {
1413 // TODO: Also handle mul by doubling the shift amount?
1414 assert((I.getOpcode() == Instruction::Add ||
1415 I.getOpcode() == Instruction::Sub) &&
1416 "Expected add/sub");
1417 auto *Op0 = dyn_cast<BinaryOperator>(Val: I.getOperand(i_nocapture: 0));
1418 auto *Op1 = dyn_cast<BinaryOperator>(Val: I.getOperand(i_nocapture: 1));
1419 if (!Op0 || !Op1 || !(Op0->hasOneUse() || Op1->hasOneUse()))
1420 return nullptr;
1421
1422 Value *X, *Y, *ShAmt;
1423 if (!match(V: Op0, P: m_Shl(L: m_Value(V&: X), R: m_Value(V&: ShAmt))) ||
1424 !match(V: Op1, P: m_Shl(L: m_Value(V&: Y), R: m_Specific(V: ShAmt))))
1425 return nullptr;
1426
1427 // No-wrap propagates only when all ops have no-wrap.
1428 bool HasNSW = I.hasNoSignedWrap() && Op0->hasNoSignedWrap() &&
1429 Op1->hasNoSignedWrap();
1430 bool HasNUW = I.hasNoUnsignedWrap() && Op0->hasNoUnsignedWrap() &&
1431 Op1->hasNoUnsignedWrap();
1432
1433 // add/sub (X << ShAmt), (Y << ShAmt) --> (add/sub X, Y) << ShAmt
1434 Value *NewMath = Builder.CreateBinOp(Opc: I.getOpcode(), LHS: X, RHS: Y);
1435 if (auto *NewI = dyn_cast<BinaryOperator>(Val: NewMath)) {
1436 NewI->setHasNoSignedWrap(HasNSW);
1437 NewI->setHasNoUnsignedWrap(HasNUW);
1438 }
1439 auto *NewShl = BinaryOperator::CreateShl(V1: NewMath, V2: ShAmt);
1440 NewShl->setHasNoSignedWrap(HasNSW);
1441 NewShl->setHasNoUnsignedWrap(HasNUW);
1442 return NewShl;
1443}
1444
1445/// Reduce a sequence of masked half-width multiplies to a single multiply.
1446/// ((XLow * YHigh) + (YLow * XHigh)) << HalfBits) + (XLow * YLow) --> X * Y
1447static Instruction *foldBoxMultiply(BinaryOperator &I) {
1448 unsigned BitWidth = I.getType()->getScalarSizeInBits();
1449 // Skip the odd bitwidth types.
1450 if ((BitWidth & 0x1))
1451 return nullptr;
1452
1453 unsigned HalfBits = BitWidth >> 1;
1454 APInt HalfMask = APInt::getMaxValue(numBits: HalfBits);
1455
1456 // ResLo = (CrossSum << HalfBits) + (YLo * XLo)
1457 Value *XLo, *YLo;
1458 Value *CrossSum;
1459 // Require one-use on the multiply to avoid increasing the number of
1460 // multiplications.
1461 if (!match(V: &I, P: m_c_Add(L: m_Shl(L: m_Value(V&: CrossSum), R: m_SpecificInt(V: HalfBits)),
1462 R: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: YLo), R: m_Value(V&: XLo))))))
1463 return nullptr;
1464
1465 // XLo = X & HalfMask
1466 // YLo = Y & HalfMask
1467 // TODO: Refactor with SimplifyDemandedBits or KnownBits known leading zeros
1468 // to enhance robustness
1469 Value *X, *Y;
1470 if (!match(V: XLo, P: m_And(L: m_Value(V&: X), R: m_SpecificInt(V: HalfMask))) ||
1471 !match(V: YLo, P: m_And(L: m_Value(V&: Y), R: m_SpecificInt(V: HalfMask))))
1472 return nullptr;
1473
1474 // CrossSum = (X' * (Y >> Halfbits)) + (Y' * (X >> HalfBits))
1475 // X' can be either X or XLo in the pattern (and the same for Y')
1476 if (match(V: CrossSum,
1477 P: m_c_Add(L: m_c_Mul(L: m_LShr(L: m_Specific(V: Y), R: m_SpecificInt(V: HalfBits)),
1478 R: m_CombineOr(L: m_Specific(V: X), R: m_Specific(V: XLo))),
1479 R: m_c_Mul(L: m_LShr(L: m_Specific(V: X), R: m_SpecificInt(V: HalfBits)),
1480 R: m_CombineOr(L: m_Specific(V: Y), R: m_Specific(V: YLo))))))
1481 return BinaryOperator::CreateMul(V1: X, V2: Y);
1482
1483 return nullptr;
1484}
1485
1486Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
1487 if (Value *V = simplifyAddInst(LHS: I.getOperand(i_nocapture: 0), RHS: I.getOperand(i_nocapture: 1),
1488 IsNSW: I.hasNoSignedWrap(), IsNUW: I.hasNoUnsignedWrap(),
1489 Q: SQ.getWithInstruction(I: &I)))
1490 return replaceInstUsesWith(I, V);
1491
1492 if (SimplifyAssociativeOrCommutative(I))
1493 return &I;
1494
1495 if (Instruction *X = foldVectorBinop(Inst&: I))
1496 return X;
1497
1498 if (Instruction *Phi = foldBinopWithPhiOperands(BO&: I))
1499 return Phi;
1500
1501 // (A*B)+(A*C) -> A*(B+C) etc
1502 if (Value *V = foldUsingDistributiveLaws(I))
1503 return replaceInstUsesWith(I, V);
1504
1505 if (Instruction *R = foldBoxMultiply(I))
1506 return R;
1507
1508 if (Instruction *R = factorizeMathWithShlOps(I, Builder))
1509 return R;
1510
1511 if (Instruction *X = foldAddWithConstant(Add&: I))
1512 return X;
1513
1514 if (Instruction *X = foldNoWrapAdd(Add&: I, Builder))
1515 return X;
1516
1517 if (Instruction *R = foldBinOpShiftWithShift(I))
1518 return R;
1519
1520 if (Instruction *R = combineAddSubWithShlAddSub(Builder, I))
1521 return R;
1522
1523 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1524 Type *Ty = I.getType();
1525 if (Ty->isIntOrIntVectorTy(BitWidth: 1))
1526 return BinaryOperator::CreateXor(V1: LHS, V2: RHS);
1527
1528 // X + X --> X << 1
1529 if (LHS == RHS) {
1530 auto *Shl = BinaryOperator::CreateShl(V1: LHS, V2: ConstantInt::get(Ty, V: 1));
1531 Shl->setHasNoSignedWrap(I.hasNoSignedWrap());
1532 Shl->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
1533 return Shl;
1534 }
1535
1536 Value *A, *B;
1537 if (match(V: LHS, P: m_Neg(V: m_Value(V&: A)))) {
1538 // -A + -B --> -(A + B)
1539 if (match(V: RHS, P: m_Neg(V: m_Value(V&: B))))
1540 return BinaryOperator::CreateNeg(Op: Builder.CreateAdd(LHS: A, RHS: B));
1541
1542 // -A + B --> B - A
1543 auto *Sub = BinaryOperator::CreateSub(V1: RHS, V2: A);
1544 auto *OB0 = cast<OverflowingBinaryOperator>(Val: LHS);
1545 Sub->setHasNoSignedWrap(I.hasNoSignedWrap() && OB0->hasNoSignedWrap());
1546
1547 return Sub;
1548 }
1549
1550 // A + -B --> A - B
1551 if (match(V: RHS, P: m_Neg(V: m_Value(V&: B))))
1552 return BinaryOperator::CreateSub(V1: LHS, V2: B);
1553
1554 if (Value *V = checkForNegativeOperand(I, Builder))
1555 return replaceInstUsesWith(I, V);
1556
1557 // (A + 1) + ~B --> A - B
1558 // ~B + (A + 1) --> A - B
1559 // (~B + A) + 1 --> A - B
1560 // (A + ~B) + 1 --> A - B
1561 if (match(V: &I, P: m_c_BinOp(L: m_Add(L: m_Value(V&: A), R: m_One()), R: m_Not(V: m_Value(V&: B)))) ||
1562 match(V: &I, P: m_BinOp(L: m_c_Add(L: m_Not(V: m_Value(V&: B)), R: m_Value(V&: A)), R: m_One())))
1563 return BinaryOperator::CreateSub(V1: A, V2: B);
1564
1565 // (A + RHS) + RHS --> A + (RHS << 1)
1566 if (match(V: LHS, P: m_OneUse(SubPattern: m_c_Add(L: m_Value(V&: A), R: m_Specific(V: RHS)))))
1567 return BinaryOperator::CreateAdd(V1: A, V2: Builder.CreateShl(LHS: RHS, RHS: 1, Name: "reass.add"));
1568
1569 // LHS + (A + LHS) --> A + (LHS << 1)
1570 if (match(V: RHS, P: m_OneUse(SubPattern: m_c_Add(L: m_Value(V&: A), R: m_Specific(V: LHS)))))
1571 return BinaryOperator::CreateAdd(V1: A, V2: Builder.CreateShl(LHS, RHS: 1, Name: "reass.add"));
1572
1573 {
1574 // (A + C1) + (C2 - B) --> (A - B) + (C1 + C2)
1575 Constant *C1, *C2;
1576 if (match(V: &I, P: m_c_Add(L: m_Add(L: m_Value(V&: A), R: m_ImmConstant(C&: C1)),
1577 R: m_Sub(L: m_ImmConstant(C&: C2), R: m_Value(V&: B)))) &&
1578 (LHS->hasOneUse() || RHS->hasOneUse())) {
1579 Value *Sub = Builder.CreateSub(LHS: A, RHS: B);
1580 return BinaryOperator::CreateAdd(V1: Sub, V2: ConstantExpr::getAdd(C1, C2));
1581 }
1582
1583 // Canonicalize a constant sub operand as an add operand for better folding:
1584 // (C1 - A) + B --> (B - A) + C1
1585 if (match(V: &I, P: m_c_Add(L: m_OneUse(SubPattern: m_Sub(L: m_ImmConstant(C&: C1), R: m_Value(V&: A))),
1586 R: m_Value(V&: B)))) {
1587 Value *Sub = Builder.CreateSub(LHS: B, RHS: A, Name: "reass.sub");
1588 return BinaryOperator::CreateAdd(V1: Sub, V2: C1);
1589 }
1590 }
1591
1592 // X % C0 + (( X / C0 ) % C1) * C0 => X % (C0 * C1)
1593 if (Value *V = SimplifyAddWithRemainder(I)) return replaceInstUsesWith(I, V);
1594
1595 // ((X s/ C1) << C2) + X => X s% -C1 where -C1 is 1 << C2
1596 const APInt *C1, *C2;
1597 if (match(V: LHS, P: m_Shl(L: m_SDiv(L: m_Specific(V: RHS), R: m_APInt(Res&: C1)), R: m_APInt(Res&: C2)))) {
1598 APInt one(C2->getBitWidth(), 1);
1599 APInt minusC1 = -(*C1);
1600 if (minusC1 == (one << *C2)) {
1601 Constant *NewRHS = ConstantInt::get(Ty: RHS->getType(), V: minusC1);
1602 return BinaryOperator::CreateSRem(V1: RHS, V2: NewRHS);
1603 }
1604 }
1605
1606 // (A & 2^C1) + A => A & (2^C1 - 1) iff bit C1 in A is a sign bit
1607 if (match(V: &I, P: m_c_Add(L: m_And(L: m_Value(V&: A), R: m_APInt(Res&: C1)), R: m_Deferred(V: A))) &&
1608 C1->isPowerOf2() && (ComputeNumSignBits(Op: A) > C1->countl_zero())) {
1609 Constant *NewMask = ConstantInt::get(Ty: RHS->getType(), V: *C1 - 1);
1610 return BinaryOperator::CreateAnd(V1: A, V2: NewMask);
1611 }
1612
1613 // ZExt (B - A) + ZExt(A) --> ZExt(B)
1614 if ((match(V: RHS, P: m_ZExt(Op: m_Value(V&: A))) &&
1615 match(V: LHS, P: m_ZExt(Op: m_NUWSub(L: m_Value(V&: B), R: m_Specific(V: A))))) ||
1616 (match(V: LHS, P: m_ZExt(Op: m_Value(V&: A))) &&
1617 match(V: RHS, P: m_ZExt(Op: m_NUWSub(L: m_Value(V&: B), R: m_Specific(V: A))))))
1618 return new ZExtInst(B, LHS->getType());
1619
1620 // zext(A) + sext(A) --> 0 if A is i1
1621 if (match(V: &I, P: m_c_BinOp(L: m_ZExt(Op: m_Value(V&: A)), R: m_SExt(Op: m_Deferred(V: A)))) &&
1622 A->getType()->isIntOrIntVectorTy(BitWidth: 1))
1623 return replaceInstUsesWith(I, V: Constant::getNullValue(Ty: I.getType()));
1624
1625 // A+B --> A|B iff A and B have no bits set in common.
1626 WithCache<const Value *> LHSCache(LHS), RHSCache(RHS);
1627 if (haveNoCommonBitsSet(LHSCache, RHSCache, SQ: SQ.getWithInstruction(I: &I)))
1628 return BinaryOperator::CreateDisjointOr(V1: LHS, V2: RHS);
1629
1630 if (Instruction *Ext = narrowMathIfNoOverflow(I))
1631 return Ext;
1632
1633 // (add (xor A, B) (and A, B)) --> (or A, B)
1634 // (add (and A, B) (xor A, B)) --> (or A, B)
1635 if (match(V: &I, P: m_c_BinOp(L: m_Xor(L: m_Value(V&: A), R: m_Value(V&: B)),
1636 R: m_c_And(L: m_Deferred(V: A), R: m_Deferred(V: B)))))
1637 return BinaryOperator::CreateOr(V1: A, V2: B);
1638
1639 // (add (or A, B) (and A, B)) --> (add A, B)
1640 // (add (and A, B) (or A, B)) --> (add A, B)
1641 if (match(V: &I, P: m_c_BinOp(L: m_Or(L: m_Value(V&: A), R: m_Value(V&: B)),
1642 R: m_c_And(L: m_Deferred(V: A), R: m_Deferred(V: B))))) {
1643 // Replacing operands in-place to preserve nuw/nsw flags.
1644 replaceOperand(I, OpNum: 0, V: A);
1645 replaceOperand(I, OpNum: 1, V: B);
1646 return &I;
1647 }
1648
1649 // (add A (or A, -A)) --> (and (add A, -1) A)
1650 // (add A (or -A, A)) --> (and (add A, -1) A)
1651 // (add (or A, -A) A) --> (and (add A, -1) A)
1652 // (add (or -A, A) A) --> (and (add A, -1) A)
1653 if (match(V: &I, P: m_c_BinOp(L: m_Value(V&: A), R: m_OneUse(SubPattern: m_c_Or(L: m_Neg(V: m_Deferred(V: A)),
1654 R: m_Deferred(V: A)))))) {
1655 Value *Add =
1656 Builder.CreateAdd(LHS: A, RHS: Constant::getAllOnesValue(Ty: A->getType()), Name: "",
1657 HasNUW: I.hasNoUnsignedWrap(), HasNSW: I.hasNoSignedWrap());
1658 return BinaryOperator::CreateAnd(V1: Add, V2: A);
1659 }
1660
1661 // Canonicalize ((A & -A) - 1) --> ((A - 1) & ~A)
1662 // Forms all commutable operations, and simplifies ctpop -> cttz folds.
1663 if (match(V: &I,
1664 P: m_Add(L: m_OneUse(SubPattern: m_c_And(L: m_Value(V&: A), R: m_OneUse(SubPattern: m_Neg(V: m_Deferred(V: A))))),
1665 R: m_AllOnes()))) {
1666 Constant *AllOnes = ConstantInt::getAllOnesValue(Ty: RHS->getType());
1667 Value *Dec = Builder.CreateAdd(LHS: A, RHS: AllOnes);
1668 Value *Not = Builder.CreateXor(LHS: A, RHS: AllOnes);
1669 return BinaryOperator::CreateAnd(V1: Dec, V2: Not);
1670 }
1671
1672 // Disguised reassociation/factorization:
1673 // ~(A * C1) + A
1674 // ((A * -C1) - 1) + A
1675 // ((A * -C1) + A) - 1
1676 // (A * (1 - C1)) - 1
1677 if (match(V: &I,
1678 P: m_c_Add(L: m_OneUse(SubPattern: m_Not(V: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: A), R: m_APInt(Res&: C1))))),
1679 R: m_Deferred(V: A)))) {
1680 Type *Ty = I.getType();
1681 Constant *NewMulC = ConstantInt::get(Ty, V: 1 - *C1);
1682 Value *NewMul = Builder.CreateMul(LHS: A, RHS: NewMulC);
1683 return BinaryOperator::CreateAdd(V1: NewMul, V2: ConstantInt::getAllOnesValue(Ty));
1684 }
1685
1686 // (A * -2**C) + B --> B - (A << C)
1687 const APInt *NegPow2C;
1688 if (match(V: &I, P: m_c_Add(L: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: A), R: m_NegatedPower2(V&: NegPow2C))),
1689 R: m_Value(V&: B)))) {
1690 Constant *ShiftAmtC = ConstantInt::get(Ty, V: NegPow2C->countr_zero());
1691 Value *Shl = Builder.CreateShl(LHS: A, RHS: ShiftAmtC);
1692 return BinaryOperator::CreateSub(V1: B, V2: Shl);
1693 }
1694
1695 // Canonicalize signum variant that ends in add:
1696 // (A s>> (BW - 1)) + (zext (A s> 0)) --> (A s>> (BW - 1)) | (zext (A != 0))
1697 ICmpInst::Predicate Pred;
1698 uint64_t BitWidth = Ty->getScalarSizeInBits();
1699 if (match(V: LHS, P: m_AShr(L: m_Value(V&: A), R: m_SpecificIntAllowPoison(V: BitWidth - 1))) &&
1700 match(V: RHS, P: m_OneUse(SubPattern: m_ZExt(
1701 Op: m_OneUse(SubPattern: m_ICmp(Pred, L: m_Specific(V: A), R: m_ZeroInt()))))) &&
1702 Pred == CmpInst::ICMP_SGT) {
1703 Value *NotZero = Builder.CreateIsNotNull(Arg: A, Name: "isnotnull");
1704 Value *Zext = Builder.CreateZExt(V: NotZero, DestTy: Ty, Name: "isnotnull.zext");
1705 return BinaryOperator::CreateOr(V1: LHS, V2: Zext);
1706 }
1707
1708 {
1709 Value *Cond, *Ext;
1710 Constant *C;
1711 // (add X, (sext/zext (icmp eq X, C)))
1712 // -> (select (icmp eq X, C), (add C, (sext/zext 1)), X)
1713 auto CondMatcher = m_CombineAnd(
1714 L: m_Value(V&: Cond), R: m_ICmp(Pred, L: m_Deferred(V: A), R: m_ImmConstant(C)));
1715
1716 if (match(V: &I,
1717 P: m_c_Add(L: m_Value(V&: A),
1718 R: m_CombineAnd(L: m_Value(V&: Ext), R: m_ZExtOrSExt(Op: CondMatcher)))) &&
1719 Pred == ICmpInst::ICMP_EQ && Ext->hasOneUse()) {
1720 Value *Add = isa<ZExtInst>(Val: Ext) ? InstCombiner::AddOne(C)
1721 : InstCombiner::SubOne(C);
1722 return replaceInstUsesWith(I, V: Builder.CreateSelect(C: Cond, True: Add, False: A));
1723 }
1724 }
1725
1726 if (Instruction *Ashr = foldAddToAshr(Add&: I))
1727 return Ashr;
1728
1729 // (~X) + (~Y) --> -2 - (X + Y)
1730 {
1731 // To ensure we can save instructions we need to ensure that we consume both
1732 // LHS/RHS (i.e they have a `not`).
1733 bool ConsumesLHS, ConsumesRHS;
1734 if (isFreeToInvert(V: LHS, WillInvertAllUses: LHS->hasOneUse(), DoesConsume&: ConsumesLHS) && ConsumesLHS &&
1735 isFreeToInvert(V: RHS, WillInvertAllUses: RHS->hasOneUse(), DoesConsume&: ConsumesRHS) && ConsumesRHS) {
1736 Value *NotLHS = getFreelyInverted(V: LHS, WillInvertAllUses: LHS->hasOneUse(), Builder: &Builder);
1737 Value *NotRHS = getFreelyInverted(V: RHS, WillInvertAllUses: RHS->hasOneUse(), Builder: &Builder);
1738 assert(NotLHS != nullptr && NotRHS != nullptr &&
1739 "isFreeToInvert desynced with getFreelyInverted");
1740 Value *LHSPlusRHS = Builder.CreateAdd(LHS: NotLHS, RHS: NotRHS);
1741 return BinaryOperator::CreateSub(
1742 V1: ConstantInt::getSigned(Ty: RHS->getType(), V: -2), V2: LHSPlusRHS);
1743 }
1744 }
1745
1746 if (Instruction *R = tryFoldInstWithCtpopWithNot(I: &I))
1747 return R;
1748
1749 // TODO(jingyue): Consider willNotOverflowSignedAdd and
1750 // willNotOverflowUnsignedAdd to reduce the number of invocations of
1751 // computeKnownBits.
1752 bool Changed = false;
1753 if (!I.hasNoSignedWrap() && willNotOverflowSignedAdd(LHS: LHSCache, RHS: RHSCache, CxtI: I)) {
1754 Changed = true;
1755 I.setHasNoSignedWrap(true);
1756 }
1757 if (!I.hasNoUnsignedWrap() &&
1758 willNotOverflowUnsignedAdd(LHS: LHSCache, RHS: RHSCache, CxtI: I)) {
1759 Changed = true;
1760 I.setHasNoUnsignedWrap(true);
1761 }
1762
1763 if (Instruction *V = canonicalizeLowbitMask(I, Builder))
1764 return V;
1765
1766 if (Instruction *V =
1767 canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I))
1768 return V;
1769
1770 if (Instruction *SatAdd = foldToUnsignedSaturatedAdd(I))
1771 return SatAdd;
1772
1773 // usub.sat(A, B) + B => umax(A, B)
1774 if (match(V: &I, P: m_c_BinOp(
1775 L: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::usub_sat>(Op0: m_Value(V&: A), Op1: m_Value(V&: B))),
1776 R: m_Deferred(V: B)))) {
1777 return replaceInstUsesWith(I,
1778 V: Builder.CreateIntrinsic(ID: Intrinsic::umax, Types: {I.getType()}, Args: {A, B}));
1779 }
1780
1781 // ctpop(A) + ctpop(B) => ctpop(A | B) if A and B have no bits set in common.
1782 if (match(V: LHS, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: A)))) &&
1783 match(V: RHS, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: B)))) &&
1784 haveNoCommonBitsSet(LHSCache: A, RHSCache: B, SQ: SQ.getWithInstruction(I: &I)))
1785 return replaceInstUsesWith(
1786 I, V: Builder.CreateIntrinsic(ID: Intrinsic::ctpop, Types: {I.getType()},
1787 Args: {Builder.CreateOr(LHS: A, RHS: B)}));
1788
1789 // Fold the log2_ceil idiom:
1790 // zext(ctpop(A) >u/!= 1) + (ctlz(A, true) ^ (BW - 1))
1791 // -->
1792 // BW - ctlz(A - 1, false)
1793 const APInt *XorC;
1794 if (match(V: &I,
1795 P: m_c_Add(
1796 L: m_ZExt(Op: m_ICmp(Pred, L: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: A)),
1797 R: m_One())),
1798 R: m_OneUse(SubPattern: m_ZExtOrSelf(Op: m_OneUse(SubPattern: m_Xor(
1799 L: m_OneUse(SubPattern: m_TruncOrSelf(Op: m_OneUse(
1800 SubPattern: m_Intrinsic<Intrinsic::ctlz>(Op0: m_Deferred(V: A), Op1: m_One())))),
1801 R: m_APInt(Res&: XorC))))))) &&
1802 (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_NE) &&
1803 *XorC == A->getType()->getScalarSizeInBits() - 1) {
1804 Value *Sub = Builder.CreateAdd(LHS: A, RHS: Constant::getAllOnesValue(Ty: A->getType()));
1805 Value *Ctlz = Builder.CreateIntrinsic(ID: Intrinsic::ctlz, Types: {A->getType()},
1806 Args: {Sub, Builder.getFalse()});
1807 Value *Ret = Builder.CreateSub(
1808 LHS: ConstantInt::get(Ty: A->getType(), V: A->getType()->getScalarSizeInBits()),
1809 RHS: Ctlz, Name: "", /*HasNUW*/ true, /*HasNSW*/ true);
1810 return replaceInstUsesWith(I, V: Builder.CreateZExtOrTrunc(V: Ret, DestTy: I.getType()));
1811 }
1812
1813 if (Instruction *Res = foldSquareSumInt(I))
1814 return Res;
1815
1816 if (Instruction *Res = foldBinOpOfDisplacedShifts(I))
1817 return Res;
1818
1819 if (Instruction *Res = foldBinOpOfSelectAndCastOfSelectCondition(I))
1820 return Res;
1821
1822 return Changed ? &I : nullptr;
1823}
1824
1825/// Eliminate an op from a linear interpolation (lerp) pattern.
1826static Instruction *factorizeLerp(BinaryOperator &I,
1827 InstCombiner::BuilderTy &Builder) {
1828 Value *X, *Y, *Z;
1829 if (!match(V: &I, P: m_c_FAdd(L: m_OneUse(SubPattern: m_c_FMul(L: m_Value(V&: Y),
1830 R: m_OneUse(SubPattern: m_FSub(L: m_FPOne(),
1831 R: m_Value(V&: Z))))),
1832 R: m_OneUse(SubPattern: m_c_FMul(L: m_Value(V&: X), R: m_Deferred(V: Z))))))
1833 return nullptr;
1834
1835 // (Y * (1.0 - Z)) + (X * Z) --> Y + Z * (X - Y) [8 commuted variants]
1836 Value *XY = Builder.CreateFSubFMF(L: X, R: Y, FMFSource: &I);
1837 Value *MulZ = Builder.CreateFMulFMF(L: Z, R: XY, FMFSource: &I);
1838 return BinaryOperator::CreateFAddFMF(V1: Y, V2: MulZ, FMFSource: &I);
1839}
1840
1841/// Factor a common operand out of fadd/fsub of fmul/fdiv.
1842static Instruction *factorizeFAddFSub(BinaryOperator &I,
1843 InstCombiner::BuilderTy &Builder) {
1844 assert((I.getOpcode() == Instruction::FAdd ||
1845 I.getOpcode() == Instruction::FSub) && "Expecting fadd/fsub");
1846 assert(I.hasAllowReassoc() && I.hasNoSignedZeros() &&
1847 "FP factorization requires FMF");
1848
1849 if (Instruction *Lerp = factorizeLerp(I, Builder))
1850 return Lerp;
1851
1852 Value *Op0 = I.getOperand(i_nocapture: 0), *Op1 = I.getOperand(i_nocapture: 1);
1853 if (!Op0->hasOneUse() || !Op1->hasOneUse())
1854 return nullptr;
1855
1856 Value *X, *Y, *Z;
1857 bool IsFMul;
1858 if ((match(V: Op0, P: m_FMul(L: m_Value(V&: X), R: m_Value(V&: Z))) &&
1859 match(V: Op1, P: m_c_FMul(L: m_Value(V&: Y), R: m_Specific(V: Z)))) ||
1860 (match(V: Op0, P: m_FMul(L: m_Value(V&: Z), R: m_Value(V&: X))) &&
1861 match(V: Op1, P: m_c_FMul(L: m_Value(V&: Y), R: m_Specific(V: Z)))))
1862 IsFMul = true;
1863 else if (match(V: Op0, P: m_FDiv(L: m_Value(V&: X), R: m_Value(V&: Z))) &&
1864 match(V: Op1, P: m_FDiv(L: m_Value(V&: Y), R: m_Specific(V: Z))))
1865 IsFMul = false;
1866 else
1867 return nullptr;
1868
1869 // (X * Z) + (Y * Z) --> (X + Y) * Z
1870 // (X * Z) - (Y * Z) --> (X - Y) * Z
1871 // (X / Z) + (Y / Z) --> (X + Y) / Z
1872 // (X / Z) - (Y / Z) --> (X - Y) / Z
1873 bool IsFAdd = I.getOpcode() == Instruction::FAdd;
1874 Value *XY = IsFAdd ? Builder.CreateFAddFMF(L: X, R: Y, FMFSource: &I)
1875 : Builder.CreateFSubFMF(L: X, R: Y, FMFSource: &I);
1876
1877 // Bail out if we just created a denormal constant.
1878 // TODO: This is copied from a previous implementation. Is it necessary?
1879 const APFloat *C;
1880 if (match(V: XY, P: m_APFloat(Res&: C)) && !C->isNormal())
1881 return nullptr;
1882
1883 return IsFMul ? BinaryOperator::CreateFMulFMF(V1: XY, V2: Z, FMFSource: &I)
1884 : BinaryOperator::CreateFDivFMF(V1: XY, V2: Z, FMFSource: &I);
1885}
1886
1887Instruction *InstCombinerImpl::visitFAdd(BinaryOperator &I) {
1888 if (Value *V = simplifyFAddInst(LHS: I.getOperand(i_nocapture: 0), RHS: I.getOperand(i_nocapture: 1),
1889 FMF: I.getFastMathFlags(),
1890 Q: SQ.getWithInstruction(I: &I)))
1891 return replaceInstUsesWith(I, V);
1892
1893 if (SimplifyAssociativeOrCommutative(I))
1894 return &I;
1895
1896 if (Instruction *X = foldVectorBinop(Inst&: I))
1897 return X;
1898
1899 if (Instruction *Phi = foldBinopWithPhiOperands(BO&: I))
1900 return Phi;
1901
1902 if (Instruction *FoldedFAdd = foldBinOpIntoSelectOrPhi(I))
1903 return FoldedFAdd;
1904
1905 // (-X) + Y --> Y - X
1906 Value *X, *Y;
1907 if (match(V: &I, P: m_c_FAdd(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y))))
1908 return BinaryOperator::CreateFSubFMF(V1: Y, V2: X, FMFSource: &I);
1909
1910 // Similar to above, but look through fmul/fdiv for the negated term.
1911 // (-X * Y) + Z --> Z - (X * Y) [4 commuted variants]
1912 Value *Z;
1913 if (match(V: &I, P: m_c_FAdd(L: m_OneUse(SubPattern: m_c_FMul(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y))),
1914 R: m_Value(V&: Z)))) {
1915 Value *XY = Builder.CreateFMulFMF(L: X, R: Y, FMFSource: &I);
1916 return BinaryOperator::CreateFSubFMF(V1: Z, V2: XY, FMFSource: &I);
1917 }
1918 // (-X / Y) + Z --> Z - (X / Y) [2 commuted variants]
1919 // (X / -Y) + Z --> Z - (X / Y) [2 commuted variants]
1920 if (match(V: &I, P: m_c_FAdd(L: m_OneUse(SubPattern: m_FDiv(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y))),
1921 R: m_Value(V&: Z))) ||
1922 match(V: &I, P: m_c_FAdd(L: m_OneUse(SubPattern: m_FDiv(L: m_Value(V&: X), R: m_FNeg(X: m_Value(V&: Y)))),
1923 R: m_Value(V&: Z)))) {
1924 Value *XY = Builder.CreateFDivFMF(L: X, R: Y, FMFSource: &I);
1925 return BinaryOperator::CreateFSubFMF(V1: Z, V2: XY, FMFSource: &I);
1926 }
1927
1928 // Check for (fadd double (sitofp x), y), see if we can merge this into an
1929 // integer add followed by a promotion.
1930 if (Instruction *R = foldFBinOpOfIntCasts(I))
1931 return R;
1932
1933 Value *LHS = I.getOperand(i_nocapture: 0), *RHS = I.getOperand(i_nocapture: 1);
1934 // Handle specials cases for FAdd with selects feeding the operation
1935 if (Value *V = SimplifySelectsFeedingBinaryOp(I, LHS, RHS))
1936 return replaceInstUsesWith(I, V);
1937
1938 if (I.hasAllowReassoc() && I.hasNoSignedZeros()) {
1939 if (Instruction *F = factorizeFAddFSub(I, Builder))
1940 return F;
1941
1942 if (Instruction *F = foldSquareSumFP(I))
1943 return F;
1944
1945 // Try to fold fadd into start value of reduction intrinsic.
1946 if (match(V: &I, P: m_c_FAdd(L: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::vector_reduce_fadd>(
1947 Op0: m_AnyZeroFP(), Op1: m_Value(V&: X))),
1948 R: m_Value(V&: Y)))) {
1949 // fadd (rdx 0.0, X), Y --> rdx Y, X
1950 return replaceInstUsesWith(
1951 I, V: Builder.CreateIntrinsic(ID: Intrinsic::vector_reduce_fadd,
1952 Types: {X->getType()}, Args: {Y, X}, FMFSource: &I));
1953 }
1954 const APFloat *StartC, *C;
1955 if (match(V: LHS, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::vector_reduce_fadd>(
1956 Op0: m_APFloat(Res&: StartC), Op1: m_Value(V&: X)))) &&
1957 match(V: RHS, P: m_APFloat(Res&: C))) {
1958 // fadd (rdx StartC, X), C --> rdx (C + StartC), X
1959 Constant *NewStartC = ConstantFP::get(Ty: I.getType(), V: *C + *StartC);
1960 return replaceInstUsesWith(
1961 I, V: Builder.CreateIntrinsic(ID: Intrinsic::vector_reduce_fadd,
1962 Types: {X->getType()}, Args: {NewStartC, X}, FMFSource: &I));
1963 }
1964
1965 // (X * MulC) + X --> X * (MulC + 1.0)
1966 Constant *MulC;
1967 if (match(V: &I, P: m_c_FAdd(L: m_FMul(L: m_Value(V&: X), R: m_ImmConstant(C&: MulC)),
1968 R: m_Deferred(V: X)))) {
1969 if (Constant *NewMulC = ConstantFoldBinaryOpOperands(
1970 Opcode: Instruction::FAdd, LHS: MulC, RHS: ConstantFP::get(Ty: I.getType(), V: 1.0), DL))
1971 return BinaryOperator::CreateFMulFMF(V1: X, V2: NewMulC, FMFSource: &I);
1972 }
1973
1974 // (-X - Y) + (X + Z) --> Z - Y
1975 if (match(V: &I, P: m_c_FAdd(L: m_FSub(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y)),
1976 R: m_c_FAdd(L: m_Deferred(V: X), R: m_Value(V&: Z)))))
1977 return BinaryOperator::CreateFSubFMF(V1: Z, V2: Y, FMFSource: &I);
1978
1979 if (Value *V = FAddCombine(Builder).simplify(I: &I))
1980 return replaceInstUsesWith(I, V);
1981 }
1982
1983 // minumum(X, Y) + maximum(X, Y) => X + Y.
1984 if (match(V: &I,
1985 P: m_c_FAdd(L: m_Intrinsic<Intrinsic::maximum>(Op0: m_Value(V&: X), Op1: m_Value(V&: Y)),
1986 R: m_c_Intrinsic<Intrinsic::minimum>(Op0: m_Deferred(V: X),
1987 Op1: m_Deferred(V: Y))))) {
1988 BinaryOperator *Result = BinaryOperator::CreateFAddFMF(V1: X, V2: Y, FMFSource: &I);
1989 // We cannot preserve ninf if nnan flag is not set.
1990 // If X is NaN and Y is Inf then in original program we had NaN + NaN,
1991 // while in optimized version NaN + Inf and this is a poison with ninf flag.
1992 if (!Result->hasNoNaNs())
1993 Result->setHasNoInfs(false);
1994 return Result;
1995 }
1996
1997 return nullptr;
1998}
1999
2000/// Optimize pointer differences into the same array into a size. Consider:
2001/// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer
2002/// operands to the ptrtoint instructions for the LHS/RHS of the subtract.
2003Value *InstCombinerImpl::OptimizePointerDifference(Value *LHS, Value *RHS,
2004 Type *Ty, bool IsNUW) {
2005 // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize
2006 // this.
2007 bool Swapped = false;
2008 GEPOperator *GEP1 = nullptr, *GEP2 = nullptr;
2009 if (!isa<GEPOperator>(Val: LHS) && isa<GEPOperator>(Val: RHS)) {
2010 std::swap(a&: LHS, b&: RHS);
2011 Swapped = true;
2012 }
2013
2014 // Require at least one GEP with a common base pointer on both sides.
2015 if (auto *LHSGEP = dyn_cast<GEPOperator>(Val: LHS)) {
2016 // (gep X, ...) - X
2017 if (LHSGEP->getOperand(i_nocapture: 0)->stripPointerCasts() ==
2018 RHS->stripPointerCasts()) {
2019 GEP1 = LHSGEP;
2020 } else if (auto *RHSGEP = dyn_cast<GEPOperator>(Val: RHS)) {
2021 // (gep X, ...) - (gep X, ...)
2022 if (LHSGEP->getOperand(i_nocapture: 0)->stripPointerCasts() ==
2023 RHSGEP->getOperand(i_nocapture: 0)->stripPointerCasts()) {
2024 GEP1 = LHSGEP;
2025 GEP2 = RHSGEP;
2026 }
2027 }
2028 }
2029
2030 if (!GEP1)
2031 return nullptr;
2032
2033 // To avoid duplicating the offset arithmetic, rewrite the GEP to use the
2034 // computed offset. This may erase the original GEP, so be sure to cache the
2035 // inbounds flag before emitting the offset.
2036 // TODO: We should probably do this even if there is only one GEP.
2037 bool RewriteGEPs = GEP2 != nullptr;
2038
2039 // Emit the offset of the GEP and an intptr_t.
2040 bool GEP1IsInBounds = GEP1->isInBounds();
2041 Value *Result = EmitGEPOffset(GEP: GEP1, RewriteGEP: RewriteGEPs);
2042
2043 // If this is a single inbounds GEP and the original sub was nuw,
2044 // then the final multiplication is also nuw.
2045 if (auto *I = dyn_cast<Instruction>(Val: Result))
2046 if (IsNUW && !GEP2 && !Swapped && GEP1IsInBounds &&
2047 I->getOpcode() == Instruction::Mul)
2048 I->setHasNoUnsignedWrap();
2049
2050 // If we have a 2nd GEP of the same base pointer, subtract the offsets.
2051 // If both GEPs are inbounds, then the subtract does not have signed overflow.
2052 if (GEP2) {
2053 bool GEP2IsInBounds = GEP2->isInBounds();
2054 Value *Offset = EmitGEPOffset(GEP: GEP2, RewriteGEP: RewriteGEPs);
2055 Result = Builder.CreateSub(LHS: Result, RHS: Offset, Name: "gepdiff", /* NUW */ HasNUW: false,
2056 HasNSW: GEP1IsInBounds && GEP2IsInBounds);
2057 }
2058
2059 // If we have p - gep(p, ...) then we have to negate the result.
2060 if (Swapped)
2061 Result = Builder.CreateNeg(V: Result, Name: "diff.neg");
2062
2063 return Builder.CreateIntCast(V: Result, DestTy: Ty, isSigned: true);
2064}
2065
2066static Instruction *foldSubOfMinMax(BinaryOperator &I,
2067 InstCombiner::BuilderTy &Builder) {
2068 Value *Op0 = I.getOperand(i_nocapture: 0);
2069 Value *Op1 = I.getOperand(i_nocapture: 1);
2070 Type *Ty = I.getType();
2071 auto *MinMax = dyn_cast<MinMaxIntrinsic>(Val: Op1);
2072 if (!MinMax)
2073 return nullptr;
2074
2075 // sub(add(X,Y), s/umin(X,Y)) --> s/umax(X,Y)
2076 // sub(add(X,Y), s/umax(X,Y)) --> s/umin(X,Y)
2077 Value *X = MinMax->getLHS();
2078 Value *Y = MinMax->getRHS();
2079 if (match(V: Op0, P: m_c_Add(L: m_Specific(V: X), R: m_Specific(V: Y))) &&
2080 (Op0->hasOneUse() || Op1->hasOneUse())) {
2081 Intrinsic::ID InvID = getInverseMinMaxIntrinsic(MinMaxID: MinMax->getIntrinsicID());
2082 Function *F = Intrinsic::getDeclaration(M: I.getModule(), id: InvID, Tys: Ty);
2083 return CallInst::Create(Func: F, Args: {X, Y});
2084 }
2085
2086 // sub(add(X,Y),umin(Y,Z)) --> add(X,usub.sat(Y,Z))
2087 // sub(add(X,Z),umin(Y,Z)) --> add(X,usub.sat(Z,Y))
2088 Value *Z;
2089 if (match(V: Op1, P: m_OneUse(SubPattern: m_UMin(L: m_Value(V&: Y), R: m_Value(V&: Z))))) {
2090 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_Add(L: m_Specific(V: Y), R: m_Value(V&: X))))) {
2091 Value *USub = Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: Ty, Args: {Y, Z});
2092 return BinaryOperator::CreateAdd(V1: X, V2: USub);
2093 }
2094 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_Add(L: m_Specific(V: Z), R: m_Value(V&: X))))) {
2095 Value *USub = Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: Ty, Args: {Z, Y});
2096 return BinaryOperator::CreateAdd(V1: X, V2: USub);
2097 }
2098 }
2099
2100 // sub Op0, smin((sub nsw Op0, Z), 0) --> smax Op0, Z
2101 // sub Op0, smax((sub nsw Op0, Z), 0) --> smin Op0, Z
2102 if (MinMax->isSigned() && match(V: Y, P: m_ZeroInt()) &&
2103 match(V: X, P: m_NSWSub(L: m_Specific(V: Op0), R: m_Value(V&: Z)))) {
2104 Intrinsic::ID InvID = getInverseMinMaxIntrinsic(MinMaxID: MinMax->getIntrinsicID());
2105 Function *F = Intrinsic::getDeclaration(M: I.getModule(), id: InvID, Tys: Ty);
2106 return CallInst::Create(Func: F, Args: {Op0, Z});
2107 }
2108
2109 return nullptr;
2110}
2111
2112Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {
2113 if (Value *V = simplifySubInst(LHS: I.getOperand(i_nocapture: 0), RHS: I.getOperand(i_nocapture: 1),
2114 IsNSW: I.hasNoSignedWrap(), IsNUW: I.hasNoUnsignedWrap(),
2115 Q: SQ.getWithInstruction(I: &I)))
2116 return replaceInstUsesWith(I, V);
2117
2118 if (Instruction *X = foldVectorBinop(Inst&: I))
2119 return X;
2120
2121 if (Instruction *Phi = foldBinopWithPhiOperands(BO&: I))
2122 return Phi;
2123
2124 Value *Op0 = I.getOperand(i_nocapture: 0), *Op1 = I.getOperand(i_nocapture: 1);
2125
2126 // If this is a 'B = x-(-A)', change to B = x+A.
2127 // We deal with this without involving Negator to preserve NSW flag.
2128 if (Value *V = dyn_castNegVal(V: Op1)) {
2129 BinaryOperator *Res = BinaryOperator::CreateAdd(V1: Op0, V2: V);
2130
2131 if (const auto *BO = dyn_cast<BinaryOperator>(Val: Op1)) {
2132 assert(BO->getOpcode() == Instruction::Sub &&
2133 "Expected a subtraction operator!");
2134 if (BO->hasNoSignedWrap() && I.hasNoSignedWrap())
2135 Res->setHasNoSignedWrap(true);
2136 } else {
2137 if (cast<Constant>(Val: Op1)->isNotMinSignedValue() && I.hasNoSignedWrap())
2138 Res->setHasNoSignedWrap(true);
2139 }
2140
2141 return Res;
2142 }
2143
2144 // Try this before Negator to preserve NSW flag.
2145 if (Instruction *R = factorizeMathWithShlOps(I, Builder))
2146 return R;
2147
2148 Constant *C;
2149 if (match(V: Op0, P: m_ImmConstant(C))) {
2150 Value *X;
2151 Constant *C2;
2152
2153 // C-(X+C2) --> (C-C2)-X
2154 if (match(V: Op1, P: m_Add(L: m_Value(V&: X), R: m_ImmConstant(C&: C2)))) {
2155 // C-C2 never overflow, and C-(X+C2), (X+C2) has NSW/NUW
2156 // => (C-C2)-X can have NSW/NUW
2157 bool WillNotSOV = willNotOverflowSignedSub(LHS: C, RHS: C2, CxtI: I);
2158 BinaryOperator *Res =
2159 BinaryOperator::CreateSub(V1: ConstantExpr::getSub(C1: C, C2), V2: X);
2160 auto *OBO1 = cast<OverflowingBinaryOperator>(Val: Op1);
2161 Res->setHasNoSignedWrap(I.hasNoSignedWrap() && OBO1->hasNoSignedWrap() &&
2162 WillNotSOV);
2163 Res->setHasNoUnsignedWrap(I.hasNoUnsignedWrap() &&
2164 OBO1->hasNoUnsignedWrap());
2165 return Res;
2166 }
2167 }
2168
2169 auto TryToNarrowDeduceFlags = [this, &I, &Op0, &Op1]() -> Instruction * {
2170 if (Instruction *Ext = narrowMathIfNoOverflow(I))
2171 return Ext;
2172
2173 bool Changed = false;
2174 if (!I.hasNoSignedWrap() && willNotOverflowSignedSub(LHS: Op0, RHS: Op1, CxtI: I)) {
2175 Changed = true;
2176 I.setHasNoSignedWrap(true);
2177 }
2178 if (!I.hasNoUnsignedWrap() && willNotOverflowUnsignedSub(LHS: Op0, RHS: Op1, CxtI: I)) {
2179 Changed = true;
2180 I.setHasNoUnsignedWrap(true);
2181 }
2182
2183 return Changed ? &I : nullptr;
2184 };
2185
2186 // First, let's try to interpret `sub a, b` as `add a, (sub 0, b)`,
2187 // and let's try to sink `(sub 0, b)` into `b` itself. But only if this isn't
2188 // a pure negation used by a select that looks like abs/nabs.
2189 bool IsNegation = match(V: Op0, P: m_ZeroInt());
2190 if (!IsNegation || none_of(Range: I.users(), P: [&I, Op1](const User *U) {
2191 const Instruction *UI = dyn_cast<Instruction>(Val: U);
2192 if (!UI)
2193 return false;
2194 return match(V: UI,
2195 P: m_Select(C: m_Value(), L: m_Specific(V: Op1), R: m_Specific(V: &I))) ||
2196 match(V: UI, P: m_Select(C: m_Value(), L: m_Specific(V: &I), R: m_Specific(V: Op1)));
2197 })) {
2198 if (Value *NegOp1 = Negator::Negate(LHSIsZero: IsNegation, /* IsNSW */ IsNegation &&
2199 I.hasNoSignedWrap(),
2200 Root: Op1, IC&: *this))
2201 return BinaryOperator::CreateAdd(V1: NegOp1, V2: Op0);
2202 }
2203 if (IsNegation)
2204 return TryToNarrowDeduceFlags(); // Should have been handled in Negator!
2205
2206 // (A*B)-(A*C) -> A*(B-C) etc
2207 if (Value *V = foldUsingDistributiveLaws(I))
2208 return replaceInstUsesWith(I, V);
2209
2210 if (I.getType()->isIntOrIntVectorTy(BitWidth: 1))
2211 return BinaryOperator::CreateXor(V1: Op0, V2: Op1);
2212
2213 // Replace (-1 - A) with (~A).
2214 if (match(V: Op0, P: m_AllOnes()))
2215 return BinaryOperator::CreateNot(Op: Op1);
2216
2217 // (X + -1) - Y --> ~Y + X
2218 Value *X, *Y;
2219 if (match(V: Op0, P: m_OneUse(SubPattern: m_Add(L: m_Value(V&: X), R: m_AllOnes()))))
2220 return BinaryOperator::CreateAdd(V1: Builder.CreateNot(V: Op1), V2: X);
2221
2222 // Reassociate sub/add sequences to create more add instructions and
2223 // reduce dependency chains:
2224 // ((X - Y) + Z) - Op1 --> (X + Z) - (Y + Op1)
2225 Value *Z;
2226 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_Add(L: m_OneUse(SubPattern: m_Sub(L: m_Value(V&: X), R: m_Value(V&: Y))),
2227 R: m_Value(V&: Z))))) {
2228 Value *XZ = Builder.CreateAdd(LHS: X, RHS: Z);
2229 Value *YW = Builder.CreateAdd(LHS: Y, RHS: Op1);
2230 return BinaryOperator::CreateSub(V1: XZ, V2: YW);
2231 }
2232
2233 // ((X - Y) - Op1) --> X - (Y + Op1)
2234 if (match(V: Op0, P: m_OneUse(SubPattern: m_Sub(L: m_Value(V&: X), R: m_Value(V&: Y))))) {
2235 OverflowingBinaryOperator *LHSSub = cast<OverflowingBinaryOperator>(Val: Op0);
2236 bool HasNUW = I.hasNoUnsignedWrap() && LHSSub->hasNoUnsignedWrap();
2237 bool HasNSW = HasNUW && I.hasNoSignedWrap() && LHSSub->hasNoSignedWrap();
2238 Value *Add = Builder.CreateAdd(LHS: Y, RHS: Op1, Name: "", /* HasNUW */ HasNUW,
2239 /* HasNSW */ HasNSW);
2240 BinaryOperator *Sub = BinaryOperator::CreateSub(V1: X, V2: Add);
2241 Sub->setHasNoUnsignedWrap(HasNUW);
2242 Sub->setHasNoSignedWrap(HasNSW);
2243 return Sub;
2244 }
2245
2246 {
2247 // (X + Z) - (Y + Z) --> (X - Y)
2248 // This is done in other passes, but we want to be able to consume this
2249 // pattern in InstCombine so we can generate it without creating infinite
2250 // loops.
2251 if (match(V: Op0, P: m_Add(L: m_Value(V&: X), R: m_Value(V&: Z))) &&
2252 match(V: Op1, P: m_c_Add(L: m_Value(V&: Y), R: m_Specific(V: Z))))
2253 return BinaryOperator::CreateSub(V1: X, V2: Y);
2254
2255 // (X + C0) - (Y + C1) --> (X - Y) + (C0 - C1)
2256 Constant *CX, *CY;
2257 if (match(V: Op0, P: m_OneUse(SubPattern: m_Add(L: m_Value(V&: X), R: m_ImmConstant(C&: CX)))) &&
2258 match(V: Op1, P: m_OneUse(SubPattern: m_Add(L: m_Value(V&: Y), R: m_ImmConstant(C&: CY))))) {
2259 Value *OpsSub = Builder.CreateSub(LHS: X, RHS: Y);
2260 Constant *ConstsSub = ConstantExpr::getSub(C1: CX, C2: CY);
2261 return BinaryOperator::CreateAdd(V1: OpsSub, V2: ConstsSub);
2262 }
2263 }
2264
2265 // (~X) - (~Y) --> Y - X
2266 {
2267 // Need to ensure we can consume at least one of the `not` instructions,
2268 // otherwise this can inf loop.
2269 bool ConsumesOp0, ConsumesOp1;
2270 if (isFreeToInvert(V: Op0, WillInvertAllUses: Op0->hasOneUse(), DoesConsume&: ConsumesOp0) &&
2271 isFreeToInvert(V: Op1, WillInvertAllUses: Op1->hasOneUse(), DoesConsume&: ConsumesOp1) &&
2272 (ConsumesOp0 || ConsumesOp1)) {
2273 Value *NotOp0 = getFreelyInverted(V: Op0, WillInvertAllUses: Op0->hasOneUse(), Builder: &Builder);
2274 Value *NotOp1 = getFreelyInverted(V: Op1, WillInvertAllUses: Op1->hasOneUse(), Builder: &Builder);
2275 assert(NotOp0 != nullptr && NotOp1 != nullptr &&
2276 "isFreeToInvert desynced with getFreelyInverted");
2277 return BinaryOperator::CreateSub(V1: NotOp1, V2: NotOp0);
2278 }
2279 }
2280
2281 auto m_AddRdx = [](Value *&Vec) {
2282 return m_OneUse(SubPattern: m_Intrinsic<Intrinsic::vector_reduce_add>(Op0: m_Value(V&: Vec)));
2283 };
2284 Value *V0, *V1;
2285 if (match(V: Op0, P: m_AddRdx(V0)) && match(V: Op1, P: m_AddRdx(V1)) &&
2286 V0->getType() == V1->getType()) {
2287 // Difference of sums is sum of differences:
2288 // add_rdx(V0) - add_rdx(V1) --> add_rdx(V0 - V1)
2289 Value *Sub = Builder.CreateSub(LHS: V0, RHS: V1);
2290 Value *Rdx = Builder.CreateIntrinsic(ID: Intrinsic::vector_reduce_add,
2291 Types: {Sub->getType()}, Args: {Sub});
2292 return replaceInstUsesWith(I, V: Rdx);
2293 }
2294
2295 if (Constant *C = dyn_cast<Constant>(Val: Op0)) {
2296 Value *X;
2297 if (match(V: Op1, P: m_ZExt(Op: m_Value(V&: X))) && X->getType()->isIntOrIntVectorTy(BitWidth: 1))
2298 // C - (zext bool) --> bool ? C - 1 : C
2299 return SelectInst::Create(C: X, S1: InstCombiner::SubOne(C), S2: C);
2300 if (match(V: Op1, P: m_SExt(Op: m_Value(V&: X))) && X->getType()->isIntOrIntVectorTy(BitWidth: 1))
2301 // C - (sext bool) --> bool ? C + 1 : C
2302 return SelectInst::Create(C: X, S1: InstCombiner::AddOne(C), S2: C);
2303
2304 // C - ~X == X + (1+C)
2305 if (match(V: Op1, P: m_Not(V: m_Value(V&: X))))
2306 return BinaryOperator::CreateAdd(V1: X, V2: InstCombiner::AddOne(C));
2307
2308 // Try to fold constant sub into select arguments.
2309 if (SelectInst *SI = dyn_cast<SelectInst>(Val: Op1))
2310 if (Instruction *R = FoldOpIntoSelect(Op&: I, SI))
2311 return R;
2312
2313 // Try to fold constant sub into PHI values.
2314 if (PHINode *PN = dyn_cast<PHINode>(Val: Op1))
2315 if (Instruction *R = foldOpIntoPhi(I, PN))
2316 return R;
2317
2318 Constant *C2;
2319
2320 // C-(C2-X) --> X+(C-C2)
2321 if (match(V: Op1, P: m_Sub(L: m_ImmConstant(C&: C2), R: m_Value(V&: X))))
2322 return BinaryOperator::CreateAdd(V1: X, V2: ConstantExpr::getSub(C1: C, C2));
2323 }
2324
2325 const APInt *Op0C;
2326 if (match(V: Op0, P: m_APInt(Res&: Op0C))) {
2327 if (Op0C->isMask()) {
2328 // Turn this into a xor if LHS is 2^n-1 and the remaining bits are known
2329 // zero. We don't use information from dominating conditions so this
2330 // transform is easier to reverse if necessary.
2331 KnownBits RHSKnown = llvm::computeKnownBits(
2332 V: Op1, Depth: 0, Q: SQ.getWithInstruction(I: &I).getWithoutDomCondCache());
2333 if ((*Op0C | RHSKnown.Zero).isAllOnes())
2334 return BinaryOperator::CreateXor(V1: Op1, V2: Op0);
2335 }
2336
2337 // C - ((C3 -nuw X) & C2) --> (C - (C2 & C3)) + (X & C2) when:
2338 // (C3 - ((C2 & C3) - 1)) is pow2
2339 // ((C2 + C3) & ((C2 & C3) - 1)) == ((C2 & C3) - 1)
2340 // C2 is negative pow2 || sub nuw
2341 const APInt *C2, *C3;
2342 BinaryOperator *InnerSub;
2343 if (match(V: Op1, P: m_OneUse(SubPattern: m_And(L: m_BinOp(I&: InnerSub), R: m_APInt(Res&: C2)))) &&
2344 match(V: InnerSub, P: m_Sub(L: m_APInt(Res&: C3), R: m_Value(V&: X))) &&
2345 (InnerSub->hasNoUnsignedWrap() || C2->isNegatedPowerOf2())) {
2346 APInt C2AndC3 = *C2 & *C3;
2347 APInt C2AndC3Minus1 = C2AndC3 - 1;
2348 APInt C2AddC3 = *C2 + *C3;
2349 if ((*C3 - C2AndC3Minus1).isPowerOf2() &&
2350 C2AndC3Minus1.isSubsetOf(RHS: C2AddC3)) {
2351 Value *And = Builder.CreateAnd(LHS: X, RHS: ConstantInt::get(Ty: I.getType(), V: *C2));
2352 return BinaryOperator::CreateAdd(
2353 V1: And, V2: ConstantInt::get(Ty: I.getType(), V: *Op0C - C2AndC3));
2354 }
2355 }
2356 }
2357
2358 {
2359 Value *Y;
2360 // X-(X+Y) == -Y X-(Y+X) == -Y
2361 if (match(V: Op1, P: m_c_Add(L: m_Specific(V: Op0), R: m_Value(V&: Y))))
2362 return BinaryOperator::CreateNeg(Op: Y);
2363
2364 // (X-Y)-X == -Y
2365 if (match(V: Op0, P: m_Sub(L: m_Specific(V: Op1), R: m_Value(V&: Y))))
2366 return BinaryOperator::CreateNeg(Op: Y);
2367 }
2368
2369 // (sub (or A, B) (and A, B)) --> (xor A, B)
2370 {
2371 Value *A, *B;
2372 if (match(V: Op1, P: m_And(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2373 match(V: Op0, P: m_c_Or(L: m_Specific(V: A), R: m_Specific(V: B))))
2374 return BinaryOperator::CreateXor(V1: A, V2: B);
2375 }
2376
2377 // (sub (add A, B) (or A, B)) --> (and A, B)
2378 {
2379 Value *A, *B;
2380 if (match(V: Op0, P: m_Add(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2381 match(V: Op1, P: m_c_Or(L: m_Specific(V: A), R: m_Specific(V: B))))
2382 return BinaryOperator::CreateAnd(V1: A, V2: B);
2383 }
2384
2385 // (sub (add A, B) (and A, B)) --> (or A, B)
2386 {
2387 Value *A, *B;
2388 if (match(V: Op0, P: m_Add(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2389 match(V: Op1, P: m_c_And(L: m_Specific(V: A), R: m_Specific(V: B))))
2390 return BinaryOperator::CreateOr(V1: A, V2: B);
2391 }
2392
2393 // (sub (and A, B) (or A, B)) --> neg (xor A, B)
2394 {
2395 Value *A, *B;
2396 if (match(V: Op0, P: m_And(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2397 match(V: Op1, P: m_c_Or(L: m_Specific(V: A), R: m_Specific(V: B))) &&
2398 (Op0->hasOneUse() || Op1->hasOneUse()))
2399 return BinaryOperator::CreateNeg(Op: Builder.CreateXor(LHS: A, RHS: B));
2400 }
2401
2402 // (sub (or A, B), (xor A, B)) --> (and A, B)
2403 {
2404 Value *A, *B;
2405 if (match(V: Op1, P: m_Xor(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2406 match(V: Op0, P: m_c_Or(L: m_Specific(V: A), R: m_Specific(V: B))))
2407 return BinaryOperator::CreateAnd(V1: A, V2: B);
2408 }
2409
2410 // (sub (xor A, B) (or A, B)) --> neg (and A, B)
2411 {
2412 Value *A, *B;
2413 if (match(V: Op0, P: m_Xor(L: m_Value(V&: A), R: m_Value(V&: B))) &&
2414 match(V: Op1, P: m_c_Or(L: m_Specific(V: A), R: m_Specific(V: B))) &&
2415 (Op0->hasOneUse() || Op1->hasOneUse()))
2416 return BinaryOperator::CreateNeg(Op: Builder.CreateAnd(LHS: A, RHS: B));
2417 }
2418
2419 {
2420 Value *Y;
2421 // ((X | Y) - X) --> (~X & Y)
2422 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_Or(L: m_Value(V&: Y), R: m_Specific(V: Op1)))))
2423 return BinaryOperator::CreateAnd(
2424 V1: Y, V2: Builder.CreateNot(V: Op1, Name: Op1->getName() + ".not"));
2425 }
2426
2427 {
2428 // (sub (and Op1, (neg X)), Op1) --> neg (and Op1, (add X, -1))
2429 Value *X;
2430 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_And(L: m_Specific(V: Op1),
2431 R: m_OneUse(SubPattern: m_Neg(V: m_Value(V&: X))))))) {
2432 return BinaryOperator::CreateNeg(Op: Builder.CreateAnd(
2433 LHS: Op1, RHS: Builder.CreateAdd(LHS: X, RHS: Constant::getAllOnesValue(Ty: I.getType()))));
2434 }
2435 }
2436
2437 {
2438 // (sub (and Op1, C), Op1) --> neg (and Op1, ~C)
2439 Constant *C;
2440 if (match(V: Op0, P: m_OneUse(SubPattern: m_And(L: m_Specific(V: Op1), R: m_Constant(C))))) {
2441 return BinaryOperator::CreateNeg(
2442 Op: Builder.CreateAnd(LHS: Op1, RHS: Builder.CreateNot(V: C)));
2443 }
2444 }
2445
2446 {
2447 // (sub (xor X, (sext C)), (sext C)) => (select C, (neg X), X)
2448 // (sub (sext C), (xor X, (sext C))) => (select C, X, (neg X))
2449 Value *C, *X;
2450 auto m_SubXorCmp = [&C, &X](Value *LHS, Value *RHS) {
2451 return match(V: LHS, P: m_OneUse(SubPattern: m_c_Xor(L: m_Value(V&: X), R: m_Specific(V: RHS)))) &&
2452 match(V: RHS, P: m_SExt(Op: m_Value(V&: C))) &&
2453 (C->getType()->getScalarSizeInBits() == 1);
2454 };
2455 if (m_SubXorCmp(Op0, Op1))
2456 return SelectInst::Create(C, S1: Builder.CreateNeg(V: X), S2: X);
2457 if (m_SubXorCmp(Op1, Op0))
2458 return SelectInst::Create(C, S1: X, S2: Builder.CreateNeg(V: X));
2459 }
2460
2461 if (Instruction *R = tryFoldInstWithCtpopWithNot(I: &I))
2462 return R;
2463
2464 if (Instruction *R = foldSubOfMinMax(I, Builder))
2465 return R;
2466
2467 {
2468 // If we have a subtraction between some value and a select between
2469 // said value and something else, sink subtraction into select hands, i.e.:
2470 // sub (select %Cond, %TrueVal, %FalseVal), %Op1
2471 // ->
2472 // select %Cond, (sub %TrueVal, %Op1), (sub %FalseVal, %Op1)
2473 // or
2474 // sub %Op0, (select %Cond, %TrueVal, %FalseVal)
2475 // ->
2476 // select %Cond, (sub %Op0, %TrueVal), (sub %Op0, %FalseVal)
2477 // This will result in select between new subtraction and 0.
2478 auto SinkSubIntoSelect =
2479 [Ty = I.getType()](Value *Select, Value *OtherHandOfSub,
2480 auto SubBuilder) -> Instruction * {
2481 Value *Cond, *TrueVal, *FalseVal;
2482 if (!match(V: Select, P: m_OneUse(SubPattern: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: TrueVal),
2483 R: m_Value(V&: FalseVal)))))
2484 return nullptr;
2485 if (OtherHandOfSub != TrueVal && OtherHandOfSub != FalseVal)
2486 return nullptr;
2487 // While it is really tempting to just create two subtractions and let
2488 // InstCombine fold one of those to 0, it isn't possible to do so
2489 // because of worklist visitation order. So ugly it is.
2490 bool OtherHandOfSubIsTrueVal = OtherHandOfSub == TrueVal;
2491 Value *NewSub = SubBuilder(OtherHandOfSubIsTrueVal ? FalseVal : TrueVal);
2492 Constant *Zero = Constant::getNullValue(Ty);
2493 SelectInst *NewSel =
2494 SelectInst::Create(C: Cond, S1: OtherHandOfSubIsTrueVal ? Zero : NewSub,
2495 S2: OtherHandOfSubIsTrueVal ? NewSub : Zero);
2496 // Preserve prof metadata if any.
2497 NewSel->copyMetadata(SrcInst: cast<Instruction>(Val&: *Select));
2498 return NewSel;
2499 };
2500 if (Instruction *NewSel = SinkSubIntoSelect(
2501 /*Select=*/Op0, /*OtherHandOfSub=*/Op1,
2502 [Builder = &Builder, Op1](Value *OtherHandOfSelect) {
2503 return Builder->CreateSub(LHS: OtherHandOfSelect,
2504 /*OtherHandOfSub=*/RHS: Op1);
2505 }))
2506 return NewSel;
2507 if (Instruction *NewSel = SinkSubIntoSelect(
2508 /*Select=*/Op1, /*OtherHandOfSub=*/Op0,
2509 [Builder = &Builder, Op0](Value *OtherHandOfSelect) {
2510 return Builder->CreateSub(/*OtherHandOfSub=*/LHS: Op0,
2511 RHS: OtherHandOfSelect);
2512 }))
2513 return NewSel;
2514 }
2515
2516 // (X - (X & Y)) --> (X & ~Y)
2517 if (match(V: Op1, P: m_c_And(L: m_Specific(V: Op0), R: m_Value(V&: Y))) &&
2518 (Op1->hasOneUse() || isa<Constant>(Val: Y)))
2519 return BinaryOperator::CreateAnd(
2520 V1: Op0, V2: Builder.CreateNot(V: Y, Name: Y->getName() + ".not"));
2521
2522 // ~X - Min/Max(~X, Y) -> ~Min/Max(X, ~Y) - X
2523 // ~X - Min/Max(Y, ~X) -> ~Min/Max(X, ~Y) - X
2524 // Min/Max(~X, Y) - ~X -> X - ~Min/Max(X, ~Y)
2525 // Min/Max(Y, ~X) - ~X -> X - ~Min/Max(X, ~Y)
2526 // As long as Y is freely invertible, this will be neutral or a win.
2527 // Note: We don't generate the inverse max/min, just create the 'not' of
2528 // it and let other folds do the rest.
2529 if (match(V: Op0, P: m_Not(V: m_Value(V&: X))) &&
2530 match(V: Op1, P: m_c_MaxOrMin(L: m_Specific(V: Op0), R: m_Value(V&: Y))) &&
2531 !Op0->hasNUsesOrMore(N: 3) && isFreeToInvert(V: Y, WillInvertAllUses: Y->hasOneUse())) {
2532 Value *Not = Builder.CreateNot(V: Op1);
2533 return BinaryOperator::CreateSub(V1: Not, V2: X);
2534 }
2535 if (match(V: Op1, P: m_Not(V: m_Value(V&: X))) &&
2536 match(V: Op0, P: m_c_MaxOrMin(L: m_Specific(V: Op1), R: m_Value(V&: Y))) &&
2537 !Op1->hasNUsesOrMore(N: 3) && isFreeToInvert(V: Y, WillInvertAllUses: Y->hasOneUse())) {
2538 Value *Not = Builder.CreateNot(V: Op0);
2539 return BinaryOperator::CreateSub(V1: X, V2: Not);
2540 }
2541
2542 // Optimize pointer differences into the same array into a size. Consider:
2543 // &A[10] - &A[0]: we should compile this to "10".
2544 Value *LHSOp, *RHSOp;
2545 if (match(V: Op0, P: m_PtrToInt(Op: m_Value(V&: LHSOp))) &&
2546 match(V: Op1, P: m_PtrToInt(Op: m_Value(V&: RHSOp))))
2547 if (Value *Res = OptimizePointerDifference(LHS: LHSOp, RHS: RHSOp, Ty: I.getType(),
2548 IsNUW: I.hasNoUnsignedWrap()))
2549 return replaceInstUsesWith(I, V: Res);
2550
2551 // trunc(p)-trunc(q) -> trunc(p-q)
2552 if (match(V: Op0, P: m_Trunc(Op: m_PtrToInt(Op: m_Value(V&: LHSOp)))) &&
2553 match(V: Op1, P: m_Trunc(Op: m_PtrToInt(Op: m_Value(V&: RHSOp)))))
2554 if (Value *Res = OptimizePointerDifference(LHS: LHSOp, RHS: RHSOp, Ty: I.getType(),
2555 /* IsNUW */ false))
2556 return replaceInstUsesWith(I, V: Res);
2557
2558 // Canonicalize a shifty way to code absolute value to the common pattern.
2559 // There are 2 potential commuted variants.
2560 // We're relying on the fact that we only do this transform when the shift has
2561 // exactly 2 uses and the xor has exactly 1 use (otherwise, we might increase
2562 // instructions).
2563 Value *A;
2564 const APInt *ShAmt;
2565 Type *Ty = I.getType();
2566 unsigned BitWidth = Ty->getScalarSizeInBits();
2567 if (match(V: Op1, P: m_AShr(L: m_Value(V&: A), R: m_APInt(Res&: ShAmt))) &&
2568 Op1->hasNUses(N: 2) && *ShAmt == BitWidth - 1 &&
2569 match(V: Op0, P: m_OneUse(SubPattern: m_c_Xor(L: m_Specific(V: A), R: m_Specific(V: Op1))))) {
2570 // B = ashr i32 A, 31 ; smear the sign bit
2571 // sub (xor A, B), B ; flip bits if negative and subtract -1 (add 1)
2572 // --> (A < 0) ? -A : A
2573 Value *IsNeg = Builder.CreateIsNeg(Arg: A);
2574 // Copy the nsw flags from the sub to the negate.
2575 Value *NegA = I.hasNoUnsignedWrap()
2576 ? Constant::getNullValue(Ty: A->getType())
2577 : Builder.CreateNeg(V: A, Name: "", HasNSW: I.hasNoSignedWrap());
2578 return SelectInst::Create(C: IsNeg, S1: NegA, S2: A);
2579 }
2580
2581 // If we are subtracting a low-bit masked subset of some value from an add
2582 // of that same value with no low bits changed, that is clearing some low bits
2583 // of the sum:
2584 // sub (X + AddC), (X & AndC) --> and (X + AddC), ~AndC
2585 const APInt *AddC, *AndC;
2586 if (match(V: Op0, P: m_Add(L: m_Value(V&: X), R: m_APInt(Res&: AddC))) &&
2587 match(V: Op1, P: m_And(L: m_Specific(V: X), R: m_APInt(Res&: AndC)))) {
2588 unsigned Cttz = AddC->countr_zero();
2589 APInt HighMask(APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - Cttz));
2590 if ((HighMask & *AndC).isZero())
2591 return BinaryOperator::CreateAnd(V1: Op0, V2: ConstantInt::get(Ty, V: ~(*AndC)));
2592 }
2593
2594 if (Instruction *V =
2595 canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I))
2596 return V;
2597
2598 // X - usub.sat(X, Y) => umin(X, Y)
2599 if (match(V: Op1, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::usub_sat>(Op0: m_Specific(V: Op0),
2600 Op1: m_Value(V&: Y)))))
2601 return replaceInstUsesWith(
2602 I, V: Builder.CreateIntrinsic(ID: Intrinsic::umin, Types: {I.getType()}, Args: {Op0, Y}));
2603
2604 // umax(X, Op1) - Op1 --> usub.sat(X, Op1)
2605 // TODO: The one-use restriction is not strictly necessary, but it may
2606 // require improving other pattern matching and/or codegen.
2607 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_UMax(L: m_Value(V&: X), R: m_Specific(V: Op1)))))
2608 return replaceInstUsesWith(
2609 I, V: Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: {Ty}, Args: {X, Op1}));
2610
2611 // Op0 - umin(X, Op0) --> usub.sat(Op0, X)
2612 if (match(V: Op1, P: m_OneUse(SubPattern: m_c_UMin(L: m_Value(V&: X), R: m_Specific(V: Op0)))))
2613 return replaceInstUsesWith(
2614 I, V: Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: {Ty}, Args: {Op0, X}));
2615
2616 // Op0 - umax(X, Op0) --> 0 - usub.sat(X, Op0)
2617 if (match(V: Op1, P: m_OneUse(SubPattern: m_c_UMax(L: m_Value(V&: X), R: m_Specific(V: Op0))))) {
2618 Value *USub = Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: {Ty}, Args: {X, Op0});
2619 return BinaryOperator::CreateNeg(Op: USub);
2620 }
2621
2622 // umin(X, Op1) - Op1 --> 0 - usub.sat(Op1, X)
2623 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_UMin(L: m_Value(V&: X), R: m_Specific(V: Op1))))) {
2624 Value *USub = Builder.CreateIntrinsic(ID: Intrinsic::usub_sat, Types: {Ty}, Args: {Op1, X});
2625 return BinaryOperator::CreateNeg(Op: USub);
2626 }
2627
2628 // C - ctpop(X) => ctpop(~X) if C is bitwidth
2629 if (match(V: Op0, P: m_SpecificInt(V: BitWidth)) &&
2630 match(V: Op1, P: m_OneUse(SubPattern: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: X)))))
2631 return replaceInstUsesWith(
2632 I, V: Builder.CreateIntrinsic(ID: Intrinsic::ctpop, Types: {I.getType()},
2633 Args: {Builder.CreateNot(V: X)}));
2634
2635 // Reduce multiplies for difference-of-squares by factoring:
2636 // (X * X) - (Y * Y) --> (X + Y) * (X - Y)
2637 if (match(V: Op0, P: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: X), R: m_Deferred(V: X)))) &&
2638 match(V: Op1, P: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: Y), R: m_Deferred(V: Y))))) {
2639 auto *OBO0 = cast<OverflowingBinaryOperator>(Val: Op0);
2640 auto *OBO1 = cast<OverflowingBinaryOperator>(Val: Op1);
2641 bool PropagateNSW = I.hasNoSignedWrap() && OBO0->hasNoSignedWrap() &&
2642 OBO1->hasNoSignedWrap() && BitWidth > 2;
2643 bool PropagateNUW = I.hasNoUnsignedWrap() && OBO0->hasNoUnsignedWrap() &&
2644 OBO1->hasNoUnsignedWrap() && BitWidth > 1;
2645 Value *Add = Builder.CreateAdd(LHS: X, RHS: Y, Name: "add", HasNUW: PropagateNUW, HasNSW: PropagateNSW);
2646 Value *Sub = Builder.CreateSub(LHS: X, RHS: Y, Name: "sub", HasNUW: PropagateNUW, HasNSW: PropagateNSW);
2647 Value *Mul = Builder.CreateMul(LHS: Add, RHS: Sub, Name: "", HasNUW: PropagateNUW, HasNSW: PropagateNSW);
2648 return replaceInstUsesWith(I, V: Mul);
2649 }
2650
2651 // max(X,Y) nsw/nuw - min(X,Y) --> abs(X nsw - Y)
2652 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_SMax(L: m_Value(V&: X), R: m_Value(V&: Y)))) &&
2653 match(V: Op1, P: m_OneUse(SubPattern: m_c_SMin(L: m_Specific(V: X), R: m_Specific(V: Y))))) {
2654 if (I.hasNoUnsignedWrap() || I.hasNoSignedWrap()) {
2655 Value *Sub =
2656 Builder.CreateSub(LHS: X, RHS: Y, Name: "sub", /*HasNUW=*/false, /*HasNSW=*/true);
2657 Value *Call =
2658 Builder.CreateBinaryIntrinsic(ID: Intrinsic::abs, LHS: Sub, RHS: Builder.getTrue());
2659 return replaceInstUsesWith(I, V: Call);
2660 }
2661 }
2662
2663 if (Instruction *Res = foldBinOpOfSelectAndCastOfSelectCondition(I))
2664 return Res;
2665
2666 return TryToNarrowDeduceFlags();
2667}
2668
2669/// This eliminates floating-point negation in either 'fneg(X)' or
2670/// 'fsub(-0.0, X)' form by combining into a constant operand.
2671static Instruction *foldFNegIntoConstant(Instruction &I, const DataLayout &DL) {
2672 // This is limited with one-use because fneg is assumed better for
2673 // reassociation and cheaper in codegen than fmul/fdiv.
2674 // TODO: Should the m_OneUse restriction be removed?
2675 Instruction *FNegOp;
2676 if (!match(V: &I, P: m_FNeg(X: m_OneUse(SubPattern: m_Instruction(I&: FNegOp)))))
2677 return nullptr;
2678
2679 Value *X;
2680 Constant *C;
2681
2682 // Fold negation into constant operand.
2683 // -(X * C) --> X * (-C)
2684 if (match(V: FNegOp, P: m_FMul(L: m_Value(V&: X), R: m_Constant(C))))
2685 if (Constant *NegC = ConstantFoldUnaryOpOperand(Opcode: Instruction::FNeg, Op: C, DL))
2686 return BinaryOperator::CreateFMulFMF(V1: X, V2: NegC, FMFSource: &I);
2687 // -(X / C) --> X / (-C)
2688 if (match(V: FNegOp, P: m_FDiv(L: m_Value(V&: X), R: m_Constant(C))))
2689 if (Constant *NegC = ConstantFoldUnaryOpOperand(Opcode: Instruction::FNeg, Op: C, DL))
2690 return BinaryOperator::CreateFDivFMF(V1: X, V2: NegC, FMFSource: &I);
2691 // -(C / X) --> (-C) / X
2692 if (match(V: FNegOp, P: m_FDiv(L: m_Constant(C), R: m_Value(V&: X))))
2693 if (Constant *NegC = ConstantFoldUnaryOpOperand(Opcode: Instruction::FNeg, Op: C, DL)) {
2694 Instruction *FDiv = BinaryOperator::CreateFDivFMF(V1: NegC, V2: X, FMFSource: &I);
2695
2696 // Intersect 'nsz' and 'ninf' because those special value exceptions may
2697 // not apply to the fdiv. Everything else propagates from the fneg.
2698 // TODO: We could propagate nsz/ninf from fdiv alone?
2699 FastMathFlags FMF = I.getFastMathFlags();
2700 FastMathFlags OpFMF = FNegOp->getFastMathFlags();
2701 FDiv->setHasNoSignedZeros(FMF.noSignedZeros() && OpFMF.noSignedZeros());
2702 FDiv->setHasNoInfs(FMF.noInfs() && OpFMF.noInfs());
2703 return FDiv;
2704 }
2705 // With NSZ [ counter-example with -0.0: -(-0.0 + 0.0) != 0.0 + -0.0 ]:
2706 // -(X + C) --> -X + -C --> -C - X
2707 if (I.hasNoSignedZeros() && match(V: FNegOp, P: m_FAdd(L: m_Value(V&: X), R: m_Constant(C))))
2708 if (Constant *NegC = ConstantFoldUnaryOpOperand(Opcode: Instruction::FNeg, Op: C, DL))
2709 return BinaryOperator::CreateFSubFMF(V1: NegC, V2: X, FMFSource: &I);
2710
2711 return nullptr;
2712}
2713
2714Instruction *InstCombinerImpl::hoistFNegAboveFMulFDiv(Value *FNegOp,
2715 Instruction &FMFSource) {
2716 Value *X, *Y;
2717 if (match(V: FNegOp, P: m_FMul(L: m_Value(V&: X), R: m_Value(V&: Y)))) {
2718 return cast<Instruction>(Val: Builder.CreateFMulFMF(
2719 L: Builder.CreateFNegFMF(V: X, FMFSource: &FMFSource), R: Y, FMFSource: &FMFSource));
2720 }
2721
2722 if (match(V: FNegOp, P: m_FDiv(L: m_Value(V&: X), R: m_Value(V&: Y)))) {
2723 return cast<Instruction>(Val: Builder.CreateFDivFMF(
2724 L: Builder.CreateFNegFMF(V: X, FMFSource: &FMFSource), R: Y, FMFSource: &FMFSource));
2725 }
2726
2727 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: FNegOp)) {
2728 // Make sure to preserve flags and metadata on the call.
2729 if (II->getIntrinsicID() == Intrinsic::ldexp) {
2730 FastMathFlags FMF = FMFSource.getFastMathFlags() | II->getFastMathFlags();
2731 IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
2732 Builder.setFastMathFlags(FMF);
2733
2734 CallInst *New = Builder.CreateCall(
2735 Callee: II->getCalledFunction(),
2736 Args: {Builder.CreateFNeg(V: II->getArgOperand(i: 0)), II->getArgOperand(i: 1)});
2737 New->copyMetadata(SrcInst: *II);
2738 return New;
2739 }
2740 }
2741
2742 return nullptr;
2743}
2744
2745Instruction *InstCombinerImpl::visitFNeg(UnaryOperator &I) {
2746 Value *Op = I.getOperand(i_nocapture: 0);
2747
2748 if (Value *V = simplifyFNegInst(Op, FMF: I.getFastMathFlags(),
2749 Q: getSimplifyQuery().getWithInstruction(I: &I)))
2750 return replaceInstUsesWith(I, V);
2751
2752 if (Instruction *X = foldFNegIntoConstant(I, DL))
2753 return X;
2754
2755 Value *X, *Y;
2756
2757 // If we can ignore the sign of zeros: -(X - Y) --> (Y - X)
2758 if (I.hasNoSignedZeros() &&
2759 match(V: Op, P: m_OneUse(SubPattern: m_FSub(L: m_Value(V&: X), R: m_Value(V&: Y)))))
2760 return BinaryOperator::CreateFSubFMF(V1: Y, V2: X, FMFSource: &I);
2761
2762 Value *OneUse;
2763 if (!match(V: Op, P: m_OneUse(SubPattern: m_Value(V&: OneUse))))
2764 return nullptr;
2765
2766 if (Instruction *R = hoistFNegAboveFMulFDiv(FNegOp: OneUse, FMFSource&: I))
2767 return replaceInstUsesWith(I, V: R);
2768
2769 // Try to eliminate fneg if at least 1 arm of the select is negated.
2770 Value *Cond;
2771 if (match(V: OneUse, P: m_Select(C: m_Value(V&: Cond), L: m_Value(V&: X), R: m_Value(V&: Y)))) {
2772 // Unlike most transforms, this one is not safe to propagate nsz unless
2773 // it is present on the original select. We union the flags from the select
2774 // and fneg and then remove nsz if needed.
2775 auto propagateSelectFMF = [&](SelectInst *S, bool CommonOperand) {
2776 S->copyFastMathFlags(I: &I);
2777 if (auto *OldSel = dyn_cast<SelectInst>(Val: Op)) {
2778 FastMathFlags FMF = I.getFastMathFlags() | OldSel->getFastMathFlags();
2779 S->setFastMathFlags(FMF);
2780 if (!OldSel->hasNoSignedZeros() && !CommonOperand &&
2781 !isGuaranteedNotToBeUndefOrPoison(V: OldSel->getCondition()))
2782 S->setHasNoSignedZeros(false);
2783 }
2784 };
2785 // -(Cond ? -P : Y) --> Cond ? P : -Y
2786 Value *P;
2787 if (match(V: X, P: m_FNeg(X: m_Value(V&: P)))) {
2788 Value *NegY = Builder.CreateFNegFMF(V: Y, FMFSource: &I, Name: Y->getName() + ".neg");
2789 SelectInst *NewSel = SelectInst::Create(C: Cond, S1: P, S2: NegY);
2790 propagateSelectFMF(NewSel, P == Y);
2791 return NewSel;
2792 }
2793 // -(Cond ? X : -P) --> Cond ? -X : P
2794 if (match(V: Y, P: m_FNeg(X: m_Value(V&: P)))) {
2795 Value *NegX = Builder.CreateFNegFMF(V: X, FMFSource: &I, Name: X->getName() + ".neg");
2796 SelectInst *NewSel = SelectInst::Create(C: Cond, S1: NegX, S2: P);
2797 propagateSelectFMF(NewSel, P == X);
2798 return NewSel;
2799 }
2800
2801 // -(Cond ? X : C) --> Cond ? -X : -C
2802 // -(Cond ? C : Y) --> Cond ? -C : -Y
2803 if (match(V: X, P: m_ImmConstant()) || match(V: Y, P: m_ImmConstant())) {
2804 Value *NegX = Builder.CreateFNegFMF(V: X, FMFSource: &I, Name: X->getName() + ".neg");
2805 Value *NegY = Builder.CreateFNegFMF(V: Y, FMFSource: &I, Name: Y->getName() + ".neg");
2806 SelectInst *NewSel = SelectInst::Create(C: Cond, S1: NegX, S2: NegY);
2807 propagateSelectFMF(NewSel, /*CommonOperand=*/true);
2808 return NewSel;
2809 }
2810 }
2811
2812 // fneg (copysign x, y) -> copysign x, (fneg y)
2813 if (match(V: OneUse, P: m_CopySign(Op0: m_Value(V&: X), Op1: m_Value(V&: Y)))) {
2814 // The source copysign has an additional value input, so we can't propagate
2815 // flags the copysign doesn't also have.
2816 FastMathFlags FMF = I.getFastMathFlags();
2817 FMF &= cast<FPMathOperator>(Val: OneUse)->getFastMathFlags();
2818
2819 IRBuilder<>::FastMathFlagGuard FMFGuard(Builder);
2820 Builder.setFastMathFlags(FMF);
2821
2822 Value *NegY = Builder.CreateFNeg(V: Y);
2823 Value *NewCopySign = Builder.CreateCopySign(LHS: X, RHS: NegY);
2824 return replaceInstUsesWith(I, V: NewCopySign);
2825 }
2826
2827 return nullptr;
2828}
2829
2830Instruction *InstCombinerImpl::visitFSub(BinaryOperator &I) {
2831 if (Value *V = simplifyFSubInst(LHS: I.getOperand(i_nocapture: 0), RHS: I.getOperand(i_nocapture: 1),
2832 FMF: I.getFastMathFlags(),
2833 Q: getSimplifyQuery().getWithInstruction(I: &I)))
2834 return replaceInstUsesWith(I, V);
2835
2836 if (Instruction *X = foldVectorBinop(Inst&: I))
2837 return X;
2838
2839 if (Instruction *Phi = foldBinopWithPhiOperands(BO&: I))
2840 return Phi;
2841
2842 // Subtraction from -0.0 is the canonical form of fneg.
2843 // fsub -0.0, X ==> fneg X
2844 // fsub nsz 0.0, X ==> fneg nsz X
2845 //
2846 // FIXME This matcher does not respect FTZ or DAZ yet:
2847 // fsub -0.0, Denorm ==> +-0
2848 // fneg Denorm ==> -Denorm
2849 Value *Op;
2850 if (match(V: &I, P: m_FNeg(X: m_Value(V&: Op))))
2851 return UnaryOperator::CreateFNegFMF(Op, FMFSource: &I);
2852
2853 if (Instruction *X = foldFNegIntoConstant(I, DL))
2854 return X;
2855
2856 if (Instruction *R = foldFBinOpOfIntCasts(I))
2857 return R;
2858
2859 Value *X, *Y;
2860 Constant *C;
2861
2862 Value *Op0 = I.getOperand(i_nocapture: 0), *Op1 = I.getOperand(i_nocapture: 1);
2863 // If Op0 is not -0.0 or we can ignore -0.0: Z - (X - Y) --> Z + (Y - X)
2864 // Canonicalize to fadd to make analysis easier.
2865 // This can also help codegen because fadd is commutative.
2866 // Note that if this fsub was really an fneg, the fadd with -0.0 will get
2867 // killed later. We still limit that particular transform with 'hasOneUse'
2868 // because an fneg is assumed better/cheaper than a generic fsub.
2869 if (I.hasNoSignedZeros() ||
2870 cannotBeNegativeZero(V: Op0, Depth: 0, SQ: getSimplifyQuery().getWithInstruction(I: &I))) {
2871 if (match(V: Op1, P: m_OneUse(SubPattern: m_FSub(L: m_Value(V&: X), R: m_Value(V&: Y))))) {
2872 Value *NewSub = Builder.CreateFSubFMF(L: Y, R: X, FMFSource: &I);
2873 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: NewSub, FMFSource: &I);
2874 }
2875 }
2876
2877 // (-X) - Op1 --> -(X + Op1)
2878 if (I.hasNoSignedZeros() && !isa<ConstantExpr>(Val: Op0) &&
2879 match(V: Op0, P: m_OneUse(SubPattern: m_FNeg(X: m_Value(V&: X))))) {
2880 Value *FAdd = Builder.CreateFAddFMF(L: X, R: Op1, FMFSource: &I);
2881 return UnaryOperator::CreateFNegFMF(Op: FAdd, FMFSource: &I);
2882 }
2883
2884 if (isa<Constant>(Val: Op0))
2885 if (SelectInst *SI = dyn_cast<SelectInst>(Val: Op1))
2886 if (Instruction *NV = FoldOpIntoSelect(Op&: I, SI))
2887 return NV;
2888
2889 // X - C --> X + (-C)
2890 // But don't transform constant expressions because there's an inverse fold
2891 // for X + (-Y) --> X - Y.
2892 if (match(V: Op1, P: m_ImmConstant(C)))
2893 if (Constant *NegC = ConstantFoldUnaryOpOperand(Opcode: Instruction::FNeg, Op: C, DL))
2894 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: NegC, FMFSource: &I);
2895
2896 // X - (-Y) --> X + Y
2897 if (match(V: Op1, P: m_FNeg(X: m_Value(V&: Y))))
2898 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: Y, FMFSource: &I);
2899
2900 // Similar to above, but look through a cast of the negated value:
2901 // X - (fptrunc(-Y)) --> X + fptrunc(Y)
2902 Type *Ty = I.getType();
2903 if (match(V: Op1, P: m_OneUse(SubPattern: m_FPTrunc(Op: m_FNeg(X: m_Value(V&: Y))))))
2904 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: Builder.CreateFPTrunc(V: Y, DestTy: Ty), FMFSource: &I);
2905
2906 // X - (fpext(-Y)) --> X + fpext(Y)
2907 if (match(V: Op1, P: m_OneUse(SubPattern: m_FPExt(Op: m_FNeg(X: m_Value(V&: Y))))))
2908 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: Builder.CreateFPExt(V: Y, DestTy: Ty), FMFSource: &I);
2909
2910 // Similar to above, but look through fmul/fdiv of the negated value:
2911 // Op0 - (-X * Y) --> Op0 + (X * Y)
2912 // Op0 - (Y * -X) --> Op0 + (X * Y)
2913 if (match(V: Op1, P: m_OneUse(SubPattern: m_c_FMul(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y))))) {
2914 Value *FMul = Builder.CreateFMulFMF(L: X, R: Y, FMFSource: &I);
2915 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: FMul, FMFSource: &I);
2916 }
2917 // Op0 - (-X / Y) --> Op0 + (X / Y)
2918 // Op0 - (X / -Y) --> Op0 + (X / Y)
2919 if (match(V: Op1, P: m_OneUse(SubPattern: m_FDiv(L: m_FNeg(X: m_Value(V&: X)), R: m_Value(V&: Y)))) ||
2920 match(V: Op1, P: m_OneUse(SubPattern: m_FDiv(L: m_Value(V&: X), R: m_FNeg(X: m_Value(V&: Y)))))) {
2921 Value *FDiv = Builder.CreateFDivFMF(L: X, R: Y, FMFSource: &I);
2922 return BinaryOperator::CreateFAddFMF(V1: Op0, V2: FDiv, FMFSource: &I);
2923 }
2924
2925 // Handle special cases for FSub with selects feeding the operation
2926 if (Value *V = SimplifySelectsFeedingBinaryOp(I, LHS: Op0, RHS: Op1))
2927 return replaceInstUsesWith(I, V);
2928
2929 if (I.hasAllowReassoc() && I.hasNoSignedZeros()) {
2930 // (Y - X) - Y --> -X
2931 if (match(V: Op0, P: m_FSub(L: m_Specific(V: Op1), R: m_Value(V&: X))))
2932 return UnaryOperator::CreateFNegFMF(Op: X, FMFSource: &I);
2933
2934 // Y - (X + Y) --> -X
2935 // Y - (Y + X) --> -X
2936 if (match(V: Op1, P: m_c_FAdd(L: m_Specific(V: Op0), R: m_Value(V&: X))))
2937 return UnaryOperator::CreateFNegFMF(Op: X, FMFSource: &I);
2938
2939 // (X * C) - X --> X * (C - 1.0)
2940 if (match(V: Op0, P: m_FMul(L: m_Specific(V: Op1), R: m_Constant(C)))) {
2941 if (Constant *CSubOne = ConstantFoldBinaryOpOperands(
2942 Opcode: Instruction::FSub, LHS: C, RHS: ConstantFP::get(Ty, V: 1.0), DL))
2943 return BinaryOperator::CreateFMulFMF(V1: Op1, V2: CSubOne, FMFSource: &I);
2944 }
2945 // X - (X * C) --> X * (1.0 - C)
2946 if (match(V: Op1, P: m_FMul(L: m_Specific(V: Op0), R: m_Constant(C)))) {
2947 if (Constant *OneSubC = ConstantFoldBinaryOpOperands(
2948 Opcode: Instruction::FSub, LHS: ConstantFP::get(Ty, V: 1.0), RHS: C, DL))
2949 return BinaryOperator::CreateFMulFMF(V1: Op0, V2: OneSubC, FMFSource: &I);
2950 }
2951
2952 // Reassociate fsub/fadd sequences to create more fadd instructions and
2953 // reduce dependency chains:
2954 // ((X - Y) + Z) - Op1 --> (X + Z) - (Y + Op1)
2955 Value *Z;
2956 if (match(V: Op0, P: m_OneUse(SubPattern: m_c_FAdd(L: m_OneUse(SubPattern: m_FSub(L: m_Value(V&: X), R: m_Value(V&: Y))),
2957 R: m_Value(V&: Z))))) {
2958 Value *XZ = Builder.CreateFAddFMF(L: X, R: Z, FMFSource: &I);
2959 Value *YW = Builder.CreateFAddFMF(L: Y, R: Op1, FMFSource: &I);
2960 return BinaryOperator::CreateFSubFMF(V1: XZ, V2: YW, FMFSource: &I);
2961 }
2962
2963 auto m_FaddRdx = [](Value *&Sum, Value *&Vec) {
2964 return m_OneUse(SubPattern: m_Intrinsic<Intrinsic::vector_reduce_fadd>(Op0: m_Value(V&: Sum),
2965 Op1: m_Value(V&: Vec)));
2966 };
2967 Value *A0, *A1, *V0, *V1;
2968 if (match(V: Op0, P: m_FaddRdx(A0, V0)) && match(V: Op1, P: m_FaddRdx(A1, V1)) &&
2969 V0->getType() == V1->getType()) {
2970 // Difference of sums is sum of differences:
2971 // add_rdx(A0, V0) - add_rdx(A1, V1) --> add_rdx(A0, V0 - V1) - A1
2972 Value *Sub = Builder.CreateFSubFMF(L: V0, R: V1, FMFSource: &I);
2973 Value *Rdx = Builder.CreateIntrinsic(ID: Intrinsic::vector_reduce_fadd,
2974 Types: {Sub->getType()}, Args: {A0, Sub}, FMFSource: &I);
2975 return BinaryOperator::CreateFSubFMF(V1: Rdx, V2: A1, FMFSource: &I);
2976 }
2977
2978 if (Instruction *F = factorizeFAddFSub(I, Builder))
2979 return F;
2980
2981 // TODO: This performs reassociative folds for FP ops. Some fraction of the
2982 // functionality has been subsumed by simple pattern matching here and in
2983 // InstSimplify. We should let a dedicated reassociation pass handle more
2984 // complex pattern matching and remove this from InstCombine.
2985 if (Value *V = FAddCombine(Builder).simplify(I: &I))
2986 return replaceInstUsesWith(I, V);
2987
2988 // (X - Y) - Op1 --> X - (Y + Op1)
2989 if (match(V: Op0, P: m_OneUse(SubPattern: m_FSub(L: m_Value(V&: X), R: m_Value(V&: Y))))) {
2990 Value *FAdd = Builder.CreateFAddFMF(L: Y, R: Op1, FMFSource: &I);
2991 return BinaryOperator::CreateFSubFMF(V1: X, V2: FAdd, FMFSource: &I);
2992 }
2993 }
2994
2995 return nullptr;
2996}
2997