LLVM 19.0.0git
InstCombineShifts.cpp
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1//===- InstCombineShifts.cpp ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the visitShl, visitLShr, and visitAShr functions.
10//
11//===----------------------------------------------------------------------===//
12
13#include "InstCombineInternal.h"
18using namespace llvm;
19using namespace PatternMatch;
20
21#define DEBUG_TYPE "instcombine"
22
24 Value *ShAmt1) {
25 // We have two shift amounts from two different shifts. The types of those
26 // shift amounts may not match. If that's the case let's bailout now..
27 if (ShAmt0->getType() != ShAmt1->getType())
28 return false;
29
30 // As input, we have the following pattern:
31 // Sh0 (Sh1 X, Q), K
32 // We want to rewrite that as:
33 // Sh x, (Q+K) iff (Q+K) u< bitwidth(x)
34 // While we know that originally (Q+K) would not overflow
35 // (because 2 * (N-1) u<= iN -1), we have looked past extensions of
36 // shift amounts. so it may now overflow in smaller bitwidth.
37 // To ensure that does not happen, we need to ensure that the total maximal
38 // shift amount is still representable in that smaller bit width.
39 unsigned MaximalPossibleTotalShiftAmount =
40 (Sh0->getType()->getScalarSizeInBits() - 1) +
41 (Sh1->getType()->getScalarSizeInBits() - 1);
42 APInt MaximalRepresentableShiftAmount =
44 return MaximalRepresentableShiftAmount.uge(MaximalPossibleTotalShiftAmount);
45}
46
47// Given pattern:
48// (x shiftopcode Q) shiftopcode K
49// we should rewrite it as
50// x shiftopcode (Q+K) iff (Q+K) u< bitwidth(x) and
51//
52// This is valid for any shift, but they must be identical, and we must be
53// careful in case we have (zext(Q)+zext(K)) and look past extensions,
54// (Q+K) must not overflow or else (Q+K) u< bitwidth(x) is bogus.
55//
56// AnalyzeForSignBitExtraction indicates that we will only analyze whether this
57// pattern has any 2 right-shifts that sum to 1 less than original bit width.
59 BinaryOperator *Sh0, const SimplifyQuery &SQ,
60 bool AnalyzeForSignBitExtraction) {
61 // Look for a shift of some instruction, ignore zext of shift amount if any.
62 Instruction *Sh0Op0;
63 Value *ShAmt0;
64 if (!match(Sh0,
65 m_Shift(m_Instruction(Sh0Op0), m_ZExtOrSelf(m_Value(ShAmt0)))))
66 return nullptr;
67
68 // If there is a truncation between the two shifts, we must make note of it
69 // and look through it. The truncation imposes additional constraints on the
70 // transform.
71 Instruction *Sh1;
72 Value *Trunc = nullptr;
73 match(Sh0Op0,
75 m_Instruction(Sh1)));
76
77 // Inner shift: (x shiftopcode ShAmt1)
78 // Like with other shift, ignore zext of shift amount if any.
79 Value *X, *ShAmt1;
80 if (!match(Sh1, m_Shift(m_Value(X), m_ZExtOrSelf(m_Value(ShAmt1)))))
81 return nullptr;
82
83 // Verify that it would be safe to try to add those two shift amounts.
84 if (!canTryToConstantAddTwoShiftAmounts(Sh0, ShAmt0, Sh1, ShAmt1))
85 return nullptr;
86
87 // We are only looking for signbit extraction if we have two right shifts.
88 bool HadTwoRightShifts = match(Sh0, m_Shr(m_Value(), m_Value())) &&
89 match(Sh1, m_Shr(m_Value(), m_Value()));
90 // ... and if it's not two right-shifts, we know the answer already.
91 if (AnalyzeForSignBitExtraction && !HadTwoRightShifts)
92 return nullptr;
93
94 // The shift opcodes must be identical, unless we are just checking whether
95 // this pattern can be interpreted as a sign-bit-extraction.
96 Instruction::BinaryOps ShiftOpcode = Sh0->getOpcode();
97 bool IdenticalShOpcodes = Sh0->getOpcode() == Sh1->getOpcode();
98 if (!IdenticalShOpcodes && !AnalyzeForSignBitExtraction)
99 return nullptr;
100
101 // If we saw truncation, we'll need to produce extra instruction,
102 // and for that one of the operands of the shift must be one-use,
103 // unless of course we don't actually plan to produce any instructions here.
104 if (Trunc && !AnalyzeForSignBitExtraction &&
105 !match(Sh0, m_c_BinOp(m_OneUse(m_Value()), m_Value())))
106 return nullptr;
107
108 // Can we fold (ShAmt0+ShAmt1) ?
109 auto *NewShAmt = dyn_cast_or_null<Constant>(
110 simplifyAddInst(ShAmt0, ShAmt1, /*isNSW=*/false, /*isNUW=*/false,
111 SQ.getWithInstruction(Sh0)));
112 if (!NewShAmt)
113 return nullptr; // Did not simplify.
114 unsigned NewShAmtBitWidth = NewShAmt->getType()->getScalarSizeInBits();
115 unsigned XBitWidth = X->getType()->getScalarSizeInBits();
116 // Is the new shift amount smaller than the bit width of inner/new shift?
118 APInt(NewShAmtBitWidth, XBitWidth))))
119 return nullptr; // FIXME: could perform constant-folding.
120
121 // If there was a truncation, and we have a right-shift, we can only fold if
122 // we are left with the original sign bit. Likewise, if we were just checking
123 // that this is a sighbit extraction, this is the place to check it.
124 // FIXME: zero shift amount is also legal here, but we can't *easily* check
125 // more than one predicate so it's not really worth it.
126 if (HadTwoRightShifts && (Trunc || AnalyzeForSignBitExtraction)) {
127 // If it's not a sign bit extraction, then we're done.
128 if (!match(NewShAmt,
130 APInt(NewShAmtBitWidth, XBitWidth - 1))))
131 return nullptr;
132 // If it is, and that was the question, return the base value.
133 if (AnalyzeForSignBitExtraction)
134 return X;
135 }
136
137 assert(IdenticalShOpcodes && "Should not get here with different shifts.");
138
139 if (NewShAmt->getType() != X->getType()) {
140 NewShAmt = ConstantFoldCastOperand(Instruction::ZExt, NewShAmt,
141 X->getType(), SQ.DL);
142 if (!NewShAmt)
143 return nullptr;
144 }
145
146 // All good, we can do this fold.
147 BinaryOperator *NewShift = BinaryOperator::Create(ShiftOpcode, X, NewShAmt);
148
149 // The flags can only be propagated if there wasn't a trunc.
150 if (!Trunc) {
151 // If the pattern did not involve trunc, and both of the original shifts
152 // had the same flag set, preserve the flag.
153 if (ShiftOpcode == Instruction::BinaryOps::Shl) {
154 NewShift->setHasNoUnsignedWrap(Sh0->hasNoUnsignedWrap() &&
155 Sh1->hasNoUnsignedWrap());
156 NewShift->setHasNoSignedWrap(Sh0->hasNoSignedWrap() &&
157 Sh1->hasNoSignedWrap());
158 } else {
159 NewShift->setIsExact(Sh0->isExact() && Sh1->isExact());
160 }
161 }
162
163 Instruction *Ret = NewShift;
164 if (Trunc) {
165 Builder.Insert(NewShift);
166 Ret = CastInst::Create(Instruction::Trunc, NewShift, Sh0->getType());
167 }
168
169 return Ret;
170}
171
172// If we have some pattern that leaves only some low bits set, and then performs
173// left-shift of those bits, if none of the bits that are left after the final
174// shift are modified by the mask, we can omit the mask.
175//
176// There are many variants to this pattern:
177// a) (x & ((1 << MaskShAmt) - 1)) << ShiftShAmt
178// b) (x & (~(-1 << MaskShAmt))) << ShiftShAmt
179// c) (x & (-1 l>> MaskShAmt)) << ShiftShAmt
180// d) (x & ((-1 << MaskShAmt) l>> MaskShAmt)) << ShiftShAmt
181// e) ((x << MaskShAmt) l>> MaskShAmt) << ShiftShAmt
182// f) ((x << MaskShAmt) a>> MaskShAmt) << ShiftShAmt
183// All these patterns can be simplified to just:
184// x << ShiftShAmt
185// iff:
186// a,b) (MaskShAmt+ShiftShAmt) u>= bitwidth(x)
187// c,d,e,f) (ShiftShAmt-MaskShAmt) s>= 0 (i.e. ShiftShAmt u>= MaskShAmt)
188static Instruction *
190 const SimplifyQuery &Q,
191 InstCombiner::BuilderTy &Builder) {
192 assert(OuterShift->getOpcode() == Instruction::BinaryOps::Shl &&
193 "The input must be 'shl'!");
194
195 Value *Masked, *ShiftShAmt;
196 match(OuterShift,
197 m_Shift(m_Value(Masked), m_ZExtOrSelf(m_Value(ShiftShAmt))));
198
199 // *If* there is a truncation between an outer shift and a possibly-mask,
200 // then said truncation *must* be one-use, else we can't perform the fold.
201 Value *Trunc;
202 if (match(Masked, m_CombineAnd(m_Trunc(m_Value(Masked)), m_Value(Trunc))) &&
203 !Trunc->hasOneUse())
204 return nullptr;
205
206 Type *NarrowestTy = OuterShift->getType();
207 Type *WidestTy = Masked->getType();
208 bool HadTrunc = WidestTy != NarrowestTy;
209
210 // The mask must be computed in a type twice as wide to ensure
211 // that no bits are lost if the sum-of-shifts is wider than the base type.
212 Type *ExtendedTy = WidestTy->getExtendedType();
213
214 Value *MaskShAmt;
215
216 // ((1 << MaskShAmt) - 1)
217 auto MaskA = m_Add(m_Shl(m_One(), m_Value(MaskShAmt)), m_AllOnes());
218 // (~(-1 << maskNbits))
219 auto MaskB = m_Xor(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_AllOnes());
220 // (-1 l>> MaskShAmt)
221 auto MaskC = m_LShr(m_AllOnes(), m_Value(MaskShAmt));
222 // ((-1 << MaskShAmt) l>> MaskShAmt)
223 auto MaskD =
224 m_LShr(m_Shl(m_AllOnes(), m_Value(MaskShAmt)), m_Deferred(MaskShAmt));
225
226 Value *X;
227 Constant *NewMask;
228
229 if (match(Masked, m_c_And(m_CombineOr(MaskA, MaskB), m_Value(X)))) {
230 // Peek through an optional zext of the shift amount.
231 match(MaskShAmt, m_ZExtOrSelf(m_Value(MaskShAmt)));
232
233 // Verify that it would be safe to try to add those two shift amounts.
234 if (!canTryToConstantAddTwoShiftAmounts(OuterShift, ShiftShAmt, Masked,
235 MaskShAmt))
236 return nullptr;
237
238 // Can we simplify (MaskShAmt+ShiftShAmt) ?
239 auto *SumOfShAmts = dyn_cast_or_null<Constant>(simplifyAddInst(
240 MaskShAmt, ShiftShAmt, /*IsNSW=*/false, /*IsNUW=*/false, Q));
241 if (!SumOfShAmts)
242 return nullptr; // Did not simplify.
243 // In this pattern SumOfShAmts correlates with the number of low bits
244 // that shall remain in the root value (OuterShift).
245
246 // An extend of an undef value becomes zero because the high bits are never
247 // completely unknown. Replace the `undef` shift amounts with final
248 // shift bitwidth to ensure that the value remains undef when creating the
249 // subsequent shift op.
250 SumOfShAmts = Constant::replaceUndefsWith(
251 SumOfShAmts, ConstantInt::get(SumOfShAmts->getType()->getScalarType(),
252 ExtendedTy->getScalarSizeInBits()));
253 auto *ExtendedSumOfShAmts = ConstantFoldCastOperand(
254 Instruction::ZExt, SumOfShAmts, ExtendedTy, Q.DL);
255 if (!ExtendedSumOfShAmts)
256 return nullptr;
257
258 // And compute the mask as usual: ~(-1 << (SumOfShAmts))
259 auto *ExtendedAllOnes = ConstantExpr::getAllOnesValue(ExtendedTy);
260 Constant *ExtendedInvertedMask = ConstantFoldBinaryOpOperands(
261 Instruction::Shl, ExtendedAllOnes, ExtendedSumOfShAmts, Q.DL);
262 if (!ExtendedInvertedMask)
263 return nullptr;
264
265 NewMask = ConstantExpr::getNot(ExtendedInvertedMask);
266 } else if (match(Masked, m_c_And(m_CombineOr(MaskC, MaskD), m_Value(X))) ||
267 match(Masked, m_Shr(m_Shl(m_Value(X), m_Value(MaskShAmt)),
268 m_Deferred(MaskShAmt)))) {
269 // Peek through an optional zext of the shift amount.
270 match(MaskShAmt, m_ZExtOrSelf(m_Value(MaskShAmt)));
271
272 // Verify that it would be safe to try to add those two shift amounts.
273 if (!canTryToConstantAddTwoShiftAmounts(OuterShift, ShiftShAmt, Masked,
274 MaskShAmt))
275 return nullptr;
276
277 // Can we simplify (ShiftShAmt-MaskShAmt) ?
278 auto *ShAmtsDiff = dyn_cast_or_null<Constant>(simplifySubInst(
279 ShiftShAmt, MaskShAmt, /*IsNSW=*/false, /*IsNUW=*/false, Q));
280 if (!ShAmtsDiff)
281 return nullptr; // Did not simplify.
282 // In this pattern ShAmtsDiff correlates with the number of high bits that
283 // shall be unset in the root value (OuterShift).
284
285 // An extend of an undef value becomes zero because the high bits are never
286 // completely unknown. Replace the `undef` shift amounts with negated
287 // bitwidth of innermost shift to ensure that the value remains undef when
288 // creating the subsequent shift op.
289 unsigned WidestTyBitWidth = WidestTy->getScalarSizeInBits();
290 ShAmtsDiff = Constant::replaceUndefsWith(
291 ShAmtsDiff, ConstantInt::get(ShAmtsDiff->getType()->getScalarType(),
292 -WidestTyBitWidth));
293 auto *ExtendedNumHighBitsToClear = ConstantFoldCastOperand(
294 Instruction::ZExt,
295 ConstantExpr::getSub(ConstantInt::get(ShAmtsDiff->getType(),
296 WidestTyBitWidth,
297 /*isSigned=*/false),
298 ShAmtsDiff),
299 ExtendedTy, Q.DL);
300 if (!ExtendedNumHighBitsToClear)
301 return nullptr;
302
303 // And compute the mask as usual: (-1 l>> (NumHighBitsToClear))
304 auto *ExtendedAllOnes = ConstantExpr::getAllOnesValue(ExtendedTy);
305 NewMask = ConstantFoldBinaryOpOperands(Instruction::LShr, ExtendedAllOnes,
306 ExtendedNumHighBitsToClear, Q.DL);
307 if (!NewMask)
308 return nullptr;
309 } else
310 return nullptr; // Don't know anything about this pattern.
311
312 NewMask = ConstantExpr::getTrunc(NewMask, NarrowestTy);
313
314 // Does this mask has any unset bits? If not then we can just not apply it.
315 bool NeedMask = !match(NewMask, m_AllOnes());
316
317 // If we need to apply a mask, there are several more restrictions we have.
318 if (NeedMask) {
319 // The old masking instruction must go away.
320 if (!Masked->hasOneUse())
321 return nullptr;
322 // The original "masking" instruction must not have been`ashr`.
323 if (match(Masked, m_AShr(m_Value(), m_Value())))
324 return nullptr;
325 }
326
327 // If we need to apply truncation, let's do it first, since we can.
328 // We have already ensured that the old truncation will go away.
329 if (HadTrunc)
330 X = Builder.CreateTrunc(X, NarrowestTy);
331
332 // No 'NUW'/'NSW'! We no longer know that we won't shift-out non-0 bits.
333 // We didn't change the Type of this outermost shift, so we can just do it.
334 auto *NewShift = BinaryOperator::Create(OuterShift->getOpcode(), X,
335 OuterShift->getOperand(1));
336 if (!NeedMask)
337 return NewShift;
338
339 Builder.Insert(NewShift);
340 return BinaryOperator::Create(Instruction::And, NewShift, NewMask);
341}
342
343/// If we have a shift-by-constant of a bin op (bitwise logic op or add/sub w/
344/// shl) that itself has a shift-by-constant operand with identical opcode, we
345/// may be able to convert that into 2 independent shifts followed by the logic
346/// op. This eliminates a use of an intermediate value (reduces dependency
347/// chain).
349 InstCombiner::BuilderTy &Builder) {
350 assert(I.isShift() && "Expected a shift as input");
351 auto *BinInst = dyn_cast<BinaryOperator>(I.getOperand(0));
352 if (!BinInst ||
353 (!BinInst->isBitwiseLogicOp() &&
354 BinInst->getOpcode() != Instruction::Add &&
355 BinInst->getOpcode() != Instruction::Sub) ||
356 !BinInst->hasOneUse())
357 return nullptr;
358
359 Constant *C0, *C1;
360 if (!match(I.getOperand(1), m_Constant(C1)))
361 return nullptr;
362
363 Instruction::BinaryOps ShiftOpcode = I.getOpcode();
364 // Transform for add/sub only works with shl.
365 if ((BinInst->getOpcode() == Instruction::Add ||
366 BinInst->getOpcode() == Instruction::Sub) &&
367 ShiftOpcode != Instruction::Shl)
368 return nullptr;
369
370 Type *Ty = I.getType();
371
372 // Find a matching shift by constant. The fold is not valid if the sum
373 // of the shift values equals or exceeds bitwidth.
374 Value *X, *Y;
375 auto matchFirstShift = [&](Value *V, Value *W) {
376 unsigned Size = Ty->getScalarSizeInBits();
377 APInt Threshold(Size, Size);
378 return match(V, m_BinOp(ShiftOpcode, m_Value(X), m_Constant(C0))) &&
379 (V->hasOneUse() || match(W, m_ImmConstant())) &&
382 };
383
384 // Logic ops and Add are commutative, so check each operand for a match. Sub
385 // is not so we cannot reoder if we match operand(1) and need to keep the
386 // operands in their original positions.
387 bool FirstShiftIsOp1 = false;
388 if (matchFirstShift(BinInst->getOperand(0), BinInst->getOperand(1)))
389 Y = BinInst->getOperand(1);
390 else if (matchFirstShift(BinInst->getOperand(1), BinInst->getOperand(0))) {
391 Y = BinInst->getOperand(0);
392 FirstShiftIsOp1 = BinInst->getOpcode() == Instruction::Sub;
393 } else
394 return nullptr;
395
396 // shift (binop (shift X, C0), Y), C1 -> binop (shift X, C0+C1), (shift Y, C1)
397 Constant *ShiftSumC = ConstantExpr::getAdd(C0, C1);
398 Value *NewShift1 = Builder.CreateBinOp(ShiftOpcode, X, ShiftSumC);
399 Value *NewShift2 = Builder.CreateBinOp(ShiftOpcode, Y, C1);
400 Value *Op1 = FirstShiftIsOp1 ? NewShift2 : NewShift1;
401 Value *Op2 = FirstShiftIsOp1 ? NewShift1 : NewShift2;
402 return BinaryOperator::Create(BinInst->getOpcode(), Op1, Op2);
403}
404
407 return Phi;
408
409 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
410 assert(Op0->getType() == Op1->getType());
411 Type *Ty = I.getType();
412
413 // If the shift amount is a one-use `sext`, we can demote it to `zext`.
414 Value *Y;
415 if (match(Op1, m_OneUse(m_SExt(m_Value(Y))))) {
416 Value *NewExt = Builder.CreateZExt(Y, Ty, Op1->getName());
417 return BinaryOperator::Create(I.getOpcode(), Op0, NewExt);
418 }
419
420 // See if we can fold away this shift.
422 return &I;
423
424 // Try to fold constant and into select arguments.
425 if (isa<Constant>(Op0))
426 if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
427 if (Instruction *R = FoldOpIntoSelect(I, SI))
428 return R;
429
430 if (Constant *CUI = dyn_cast<Constant>(Op1))
431 if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
432 return Res;
433
434 if (auto *NewShift = cast_or_null<Instruction>(
436 return NewShift;
437
438 // Pre-shift a constant shifted by a variable amount with constant offset:
439 // C shift (A add nuw C1) --> (C shift C1) shift A
440 Value *A;
441 Constant *C, *C1;
442 if (match(Op0, m_Constant(C)) &&
443 match(Op1, m_NUWAddLike(m_Value(A), m_Constant(C1)))) {
444 Value *NewC = Builder.CreateBinOp(I.getOpcode(), C, C1);
445 BinaryOperator *NewShiftOp = BinaryOperator::Create(I.getOpcode(), NewC, A);
446 if (I.getOpcode() == Instruction::Shl) {
447 NewShiftOp->setHasNoSignedWrap(I.hasNoSignedWrap());
448 NewShiftOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
449 } else {
450 NewShiftOp->setIsExact(I.isExact());
451 }
452 return NewShiftOp;
453 }
454
455 unsigned BitWidth = Ty->getScalarSizeInBits();
456
457 const APInt *AC, *AddC;
458 // Try to pre-shift a constant shifted by a variable amount added with a
459 // negative number:
460 // C << (X - AddC) --> (C >> AddC) << X
461 // and
462 // C >> (X - AddC) --> (C << AddC) >> X
463 if (match(Op0, m_APInt(AC)) && match(Op1, m_Add(m_Value(A), m_APInt(AddC))) &&
464 AddC->isNegative() && (-*AddC).ult(BitWidth)) {
465 assert(!AC->isZero() && "Expected simplify of shifted zero");
466 unsigned PosOffset = (-*AddC).getZExtValue();
467
468 auto isSuitableForPreShift = [PosOffset, &I, AC]() {
469 switch (I.getOpcode()) {
470 default:
471 return false;
472 case Instruction::Shl:
473 return (I.hasNoSignedWrap() || I.hasNoUnsignedWrap()) &&
474 AC->eq(AC->lshr(PosOffset).shl(PosOffset));
475 case Instruction::LShr:
476 return I.isExact() && AC->eq(AC->shl(PosOffset).lshr(PosOffset));
477 case Instruction::AShr:
478 return I.isExact() && AC->eq(AC->shl(PosOffset).ashr(PosOffset));
479 }
480 };
481 if (isSuitableForPreShift()) {
482 Constant *NewC = ConstantInt::get(Ty, I.getOpcode() == Instruction::Shl
483 ? AC->lshr(PosOffset)
484 : AC->shl(PosOffset));
485 BinaryOperator *NewShiftOp =
486 BinaryOperator::Create(I.getOpcode(), NewC, A);
487 if (I.getOpcode() == Instruction::Shl) {
488 NewShiftOp->setHasNoUnsignedWrap(I.hasNoUnsignedWrap());
489 } else {
490 NewShiftOp->setIsExact();
491 }
492 return NewShiftOp;
493 }
494 }
495
496 // X shift (A srem C) -> X shift (A and (C - 1)) iff C is a power of 2.
497 // Because shifts by negative values (which could occur if A were negative)
498 // are undefined.
499 if (Op1->hasOneUse() && match(Op1, m_SRem(m_Value(A), m_Constant(C))) &&
500 match(C, m_Power2())) {
501 // FIXME: Should this get moved into SimplifyDemandedBits by saying we don't
502 // demand the sign bit (and many others) here??
503 Constant *Mask = ConstantExpr::getSub(C, ConstantInt::get(Ty, 1));
504 Value *Rem = Builder.CreateAnd(A, Mask, Op1->getName());
505 return replaceOperand(I, 1, Rem);
506 }
507
509 return Logic;
510
511 if (match(Op1, m_Or(m_Value(), m_SpecificInt(BitWidth - 1))))
512 return replaceOperand(I, 1, ConstantInt::get(Ty, BitWidth - 1));
513
514 return nullptr;
515}
516
517/// Return true if we can simplify two logical (either left or right) shifts
518/// that have constant shift amounts: OuterShift (InnerShift X, C1), C2.
519static bool canEvaluateShiftedShift(unsigned OuterShAmt, bool IsOuterShl,
520 Instruction *InnerShift,
521 InstCombinerImpl &IC, Instruction *CxtI) {
522 assert(InnerShift->isLogicalShift() && "Unexpected instruction type");
523
524 // We need constant scalar or constant splat shifts.
525 const APInt *InnerShiftConst;
526 if (!match(InnerShift->getOperand(1), m_APInt(InnerShiftConst)))
527 return false;
528
529 // Two logical shifts in the same direction:
530 // shl (shl X, C1), C2 --> shl X, C1 + C2
531 // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
532 bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
533 if (IsInnerShl == IsOuterShl)
534 return true;
535
536 // Equal shift amounts in opposite directions become bitwise 'and':
537 // lshr (shl X, C), C --> and X, C'
538 // shl (lshr X, C), C --> and X, C'
539 if (*InnerShiftConst == OuterShAmt)
540 return true;
541
542 // If the 2nd shift is bigger than the 1st, we can fold:
543 // lshr (shl X, C1), C2 --> and (shl X, C1 - C2), C3
544 // shl (lshr X, C1), C2 --> and (lshr X, C1 - C2), C3
545 // but it isn't profitable unless we know the and'd out bits are already zero.
546 // Also, check that the inner shift is valid (less than the type width) or
547 // we'll crash trying to produce the bit mask for the 'and'.
548 unsigned TypeWidth = InnerShift->getType()->getScalarSizeInBits();
549 if (InnerShiftConst->ugt(OuterShAmt) && InnerShiftConst->ult(TypeWidth)) {
550 unsigned InnerShAmt = InnerShiftConst->getZExtValue();
551 unsigned MaskShift =
552 IsInnerShl ? TypeWidth - InnerShAmt : InnerShAmt - OuterShAmt;
553 APInt Mask = APInt::getLowBitsSet(TypeWidth, OuterShAmt) << MaskShift;
554 if (IC.MaskedValueIsZero(InnerShift->getOperand(0), Mask, 0, CxtI))
555 return true;
556 }
557
558 return false;
559}
560
561/// See if we can compute the specified value, but shifted logically to the left
562/// or right by some number of bits. This should return true if the expression
563/// can be computed for the same cost as the current expression tree. This is
564/// used to eliminate extraneous shifting from things like:
565/// %C = shl i128 %A, 64
566/// %D = shl i128 %B, 96
567/// %E = or i128 %C, %D
568/// %F = lshr i128 %E, 64
569/// where the client will ask if E can be computed shifted right by 64-bits. If
570/// this succeeds, getShiftedValue() will be called to produce the value.
571static bool canEvaluateShifted(Value *V, unsigned NumBits, bool IsLeftShift,
572 InstCombinerImpl &IC, Instruction *CxtI) {
573 // We can always evaluate immediate constants.
574 if (match(V, m_ImmConstant()))
575 return true;
576
577 Instruction *I = dyn_cast<Instruction>(V);
578 if (!I) return false;
579
580 // We can't mutate something that has multiple uses: doing so would
581 // require duplicating the instruction in general, which isn't profitable.
582 if (!I->hasOneUse()) return false;
583
584 switch (I->getOpcode()) {
585 default: return false;
586 case Instruction::And:
587 case Instruction::Or:
588 case Instruction::Xor:
589 // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
590 return canEvaluateShifted(I->getOperand(0), NumBits, IsLeftShift, IC, I) &&
591 canEvaluateShifted(I->getOperand(1), NumBits, IsLeftShift, IC, I);
592
593 case Instruction::Shl:
594 case Instruction::LShr:
595 return canEvaluateShiftedShift(NumBits, IsLeftShift, I, IC, CxtI);
596
597 case Instruction::Select: {
598 SelectInst *SI = cast<SelectInst>(I);
599 Value *TrueVal = SI->getTrueValue();
600 Value *FalseVal = SI->getFalseValue();
601 return canEvaluateShifted(TrueVal, NumBits, IsLeftShift, IC, SI) &&
602 canEvaluateShifted(FalseVal, NumBits, IsLeftShift, IC, SI);
603 }
604 case Instruction::PHI: {
605 // We can change a phi if we can change all operands. Note that we never
606 // get into trouble with cyclic PHIs here because we only consider
607 // instructions with a single use.
608 PHINode *PN = cast<PHINode>(I);
609 for (Value *IncValue : PN->incoming_values())
610 if (!canEvaluateShifted(IncValue, NumBits, IsLeftShift, IC, PN))
611 return false;
612 return true;
613 }
614 case Instruction::Mul: {
615 const APInt *MulConst;
616 // We can fold (shr (mul X, -(1 << C)), C) -> (and (neg X), C`)
617 return !IsLeftShift && match(I->getOperand(1), m_APInt(MulConst)) &&
618 MulConst->isNegatedPowerOf2() && MulConst->countr_zero() == NumBits;
619 }
620 }
621}
622
623/// Fold OuterShift (InnerShift X, C1), C2.
624/// See canEvaluateShiftedShift() for the constraints on these instructions.
625static Value *foldShiftedShift(BinaryOperator *InnerShift, unsigned OuterShAmt,
626 bool IsOuterShl,
627 InstCombiner::BuilderTy &Builder) {
628 bool IsInnerShl = InnerShift->getOpcode() == Instruction::Shl;
629 Type *ShType = InnerShift->getType();
630 unsigned TypeWidth = ShType->getScalarSizeInBits();
631
632 // We only accept shifts-by-a-constant in canEvaluateShifted().
633 const APInt *C1;
634 match(InnerShift->getOperand(1), m_APInt(C1));
635 unsigned InnerShAmt = C1->getZExtValue();
636
637 // Change the shift amount and clear the appropriate IR flags.
638 auto NewInnerShift = [&](unsigned ShAmt) {
639 InnerShift->setOperand(1, ConstantInt::get(ShType, ShAmt));
640 if (IsInnerShl) {
641 InnerShift->setHasNoUnsignedWrap(false);
642 InnerShift->setHasNoSignedWrap(false);
643 } else {
644 InnerShift->setIsExact(false);
645 }
646 return InnerShift;
647 };
648
649 // Two logical shifts in the same direction:
650 // shl (shl X, C1), C2 --> shl X, C1 + C2
651 // lshr (lshr X, C1), C2 --> lshr X, C1 + C2
652 if (IsInnerShl == IsOuterShl) {
653 // If this is an oversized composite shift, then unsigned shifts get 0.
654 if (InnerShAmt + OuterShAmt >= TypeWidth)
655 return Constant::getNullValue(ShType);
656
657 return NewInnerShift(InnerShAmt + OuterShAmt);
658 }
659
660 // Equal shift amounts in opposite directions become bitwise 'and':
661 // lshr (shl X, C), C --> and X, C'
662 // shl (lshr X, C), C --> and X, C'
663 if (InnerShAmt == OuterShAmt) {
664 APInt Mask = IsInnerShl
665 ? APInt::getLowBitsSet(TypeWidth, TypeWidth - OuterShAmt)
666 : APInt::getHighBitsSet(TypeWidth, TypeWidth - OuterShAmt);
667 Value *And = Builder.CreateAnd(InnerShift->getOperand(0),
668 ConstantInt::get(ShType, Mask));
669 if (auto *AndI = dyn_cast<Instruction>(And)) {
670 AndI->moveBefore(InnerShift);
671 AndI->takeName(InnerShift);
672 }
673 return And;
674 }
675
676 assert(InnerShAmt > OuterShAmt &&
677 "Unexpected opposite direction logical shift pair");
678
679 // In general, we would need an 'and' for this transform, but
680 // canEvaluateShiftedShift() guarantees that the masked-off bits are not used.
681 // lshr (shl X, C1), C2 --> shl X, C1 - C2
682 // shl (lshr X, C1), C2 --> lshr X, C1 - C2
683 return NewInnerShift(InnerShAmt - OuterShAmt);
684}
685
686/// When canEvaluateShifted() returns true for an expression, this function
687/// inserts the new computation that produces the shifted value.
688static Value *getShiftedValue(Value *V, unsigned NumBits, bool isLeftShift,
689 InstCombinerImpl &IC, const DataLayout &DL) {
690 // We can always evaluate constants shifted.
691 if (Constant *C = dyn_cast<Constant>(V)) {
692 if (isLeftShift)
693 return IC.Builder.CreateShl(C, NumBits);
694 else
695 return IC.Builder.CreateLShr(C, NumBits);
696 }
697
698 Instruction *I = cast<Instruction>(V);
699 IC.addToWorklist(I);
700
701 switch (I->getOpcode()) {
702 default: llvm_unreachable("Inconsistency with CanEvaluateShifted");
703 case Instruction::And:
704 case Instruction::Or:
705 case Instruction::Xor:
706 // Bitwise operators can all arbitrarily be arbitrarily evaluated shifted.
707 I->setOperand(
708 0, getShiftedValue(I->getOperand(0), NumBits, isLeftShift, IC, DL));
709 I->setOperand(
710 1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
711 return I;
712
713 case Instruction::Shl:
714 case Instruction::LShr:
715 return foldShiftedShift(cast<BinaryOperator>(I), NumBits, isLeftShift,
716 IC.Builder);
717
718 case Instruction::Select:
719 I->setOperand(
720 1, getShiftedValue(I->getOperand(1), NumBits, isLeftShift, IC, DL));
721 I->setOperand(
722 2, getShiftedValue(I->getOperand(2), NumBits, isLeftShift, IC, DL));
723 return I;
724 case Instruction::PHI: {
725 // We can change a phi if we can change all operands. Note that we never
726 // get into trouble with cyclic PHIs here because we only consider
727 // instructions with a single use.
728 PHINode *PN = cast<PHINode>(I);
729 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
731 isLeftShift, IC, DL));
732 return PN;
733 }
734 case Instruction::Mul: {
735 assert(!isLeftShift && "Unexpected shift direction!");
736 auto *Neg = BinaryOperator::CreateNeg(I->getOperand(0));
737 IC.InsertNewInstWith(Neg, I->getIterator());
738 unsigned TypeWidth = I->getType()->getScalarSizeInBits();
739 APInt Mask = APInt::getLowBitsSet(TypeWidth, TypeWidth - NumBits);
740 auto *And = BinaryOperator::CreateAnd(Neg,
741 ConstantInt::get(I->getType(), Mask));
742 And->takeName(I);
743 return IC.InsertNewInstWith(And, I->getIterator());
744 }
745 }
746}
747
748// If this is a bitwise operator or add with a constant RHS we might be able
749// to pull it through a shift.
751 BinaryOperator *BO) {
752 switch (BO->getOpcode()) {
753 default:
754 return false; // Do not perform transform!
755 case Instruction::Add:
756 return Shift.getOpcode() == Instruction::Shl;
757 case Instruction::Or:
758 case Instruction::And:
759 return true;
760 case Instruction::Xor:
761 // Do not change a 'not' of logical shift because that would create a normal
762 // 'xor'. The 'not' is likely better for analysis, SCEV, and codegen.
763 return !(Shift.isLogicalShift() && match(BO, m_Not(m_Value())));
764 }
765}
766
768 BinaryOperator &I) {
769 // (C2 << X) << C1 --> (C2 << C1) << X
770 // (C2 >> X) >> C1 --> (C2 >> C1) >> X
771 Constant *C2;
772 Value *X;
773 bool IsLeftShift = I.getOpcode() == Instruction::Shl;
774 if (match(Op0, m_BinOp(I.getOpcode(), m_ImmConstant(C2), m_Value(X)))) {
776 I.getOpcode(), Builder.CreateBinOp(I.getOpcode(), C2, C1), X);
777 BinaryOperator *BO0 = cast<BinaryOperator>(Op0);
778 if (IsLeftShift) {
779 R->setHasNoUnsignedWrap(I.hasNoUnsignedWrap() &&
780 BO0->hasNoUnsignedWrap());
781 R->setHasNoSignedWrap(I.hasNoSignedWrap() && BO0->hasNoSignedWrap());
782 } else
783 R->setIsExact(I.isExact() && BO0->isExact());
784 return R;
785 }
786
787 Type *Ty = I.getType();
788 unsigned TypeBits = Ty->getScalarSizeInBits();
789
790 // (X / +DivC) >> (Width - 1) --> ext (X <= -DivC)
791 // (X / -DivC) >> (Width - 1) --> ext (X >= +DivC)
792 const APInt *DivC;
793 if (!IsLeftShift && match(C1, m_SpecificIntAllowPoison(TypeBits - 1)) &&
794 match(Op0, m_SDiv(m_Value(X), m_APInt(DivC))) && !DivC->isZero() &&
795 !DivC->isMinSignedValue()) {
796 Constant *NegDivC = ConstantInt::get(Ty, -(*DivC));
799 Value *Cmp = Builder.CreateICmp(Pred, X, NegDivC);
800 auto ExtOpcode = (I.getOpcode() == Instruction::AShr) ? Instruction::SExt
801 : Instruction::ZExt;
802 return CastInst::Create(ExtOpcode, Cmp, Ty);
803 }
804
805 const APInt *Op1C;
806 if (!match(C1, m_APInt(Op1C)))
807 return nullptr;
808
809 assert(!Op1C->uge(TypeBits) &&
810 "Shift over the type width should have been removed already");
811
812 // See if we can propagate this shift into the input, this covers the trivial
813 // cast of lshr(shl(x,c1),c2) as well as other more complex cases.
814 if (I.getOpcode() != Instruction::AShr &&
815 canEvaluateShifted(Op0, Op1C->getZExtValue(), IsLeftShift, *this, &I)) {
817 dbgs() << "ICE: GetShiftedValue propagating shift through expression"
818 " to eliminate shift:\n IN: "
819 << *Op0 << "\n SH: " << I << "\n");
820
821 return replaceInstUsesWith(
822 I, getShiftedValue(Op0, Op1C->getZExtValue(), IsLeftShift, *this, DL));
823 }
824
825 if (Instruction *FoldedShift = foldBinOpIntoSelectOrPhi(I))
826 return FoldedShift;
827
828 if (!Op0->hasOneUse())
829 return nullptr;
830
831 if (auto *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
832 // If the operand is a bitwise operator with a constant RHS, and the
833 // shift is the only use, we can pull it out of the shift.
834 const APInt *Op0C;
835 if (match(Op0BO->getOperand(1), m_APInt(Op0C))) {
836 if (canShiftBinOpWithConstantRHS(I, Op0BO)) {
837 Value *NewRHS =
838 Builder.CreateBinOp(I.getOpcode(), Op0BO->getOperand(1), C1);
839
840 Value *NewShift =
841 Builder.CreateBinOp(I.getOpcode(), Op0BO->getOperand(0), C1);
842 NewShift->takeName(Op0BO);
843
844 return BinaryOperator::Create(Op0BO->getOpcode(), NewShift, NewRHS);
845 }
846 }
847 }
848
849 // If we have a select that conditionally executes some binary operator,
850 // see if we can pull it the select and operator through the shift.
851 //
852 // For example, turning:
853 // shl (select C, (add X, C1), X), C2
854 // Into:
855 // Y = shl X, C2
856 // select C, (add Y, C1 << C2), Y
857 Value *Cond;
858 BinaryOperator *TBO;
859 Value *FalseVal;
860 if (match(Op0, m_Select(m_Value(Cond), m_OneUse(m_BinOp(TBO)),
861 m_Value(FalseVal)))) {
862 const APInt *C;
863 if (!isa<Constant>(FalseVal) && TBO->getOperand(0) == FalseVal &&
864 match(TBO->getOperand(1), m_APInt(C)) &&
866 Value *NewRHS =
867 Builder.CreateBinOp(I.getOpcode(), TBO->getOperand(1), C1);
868
869 Value *NewShift = Builder.CreateBinOp(I.getOpcode(), FalseVal, C1);
870 Value *NewOp = Builder.CreateBinOp(TBO->getOpcode(), NewShift, NewRHS);
871 return SelectInst::Create(Cond, NewOp, NewShift);
872 }
873 }
874
875 BinaryOperator *FBO;
876 Value *TrueVal;
877 if (match(Op0, m_Select(m_Value(Cond), m_Value(TrueVal),
878 m_OneUse(m_BinOp(FBO))))) {
879 const APInt *C;
880 if (!isa<Constant>(TrueVal) && FBO->getOperand(0) == TrueVal &&
881 match(FBO->getOperand(1), m_APInt(C)) &&
883 Value *NewRHS =
884 Builder.CreateBinOp(I.getOpcode(), FBO->getOperand(1), C1);
885
886 Value *NewShift = Builder.CreateBinOp(I.getOpcode(), TrueVal, C1);
887 Value *NewOp = Builder.CreateBinOp(FBO->getOpcode(), NewShift, NewRHS);
888 return SelectInst::Create(Cond, NewShift, NewOp);
889 }
890 }
891
892 return nullptr;
893}
894
895// Tries to perform
896// (lshr (add (zext X), (zext Y)), K)
897// -> (icmp ult (add X, Y), X)
898// where
899// - The add's operands are zexts from a K-bits integer to a bigger type.
900// - The add is only used by the shr, or by iK (or narrower) truncates.
901// - The lshr type has more than 2 bits (other types are boolean math).
902// - K > 1
903// note that
904// - The resulting add cannot have nuw/nsw, else on overflow we get a
905// poison value and the transform isn't legal anymore.
906Instruction *InstCombinerImpl::foldLShrOverflowBit(BinaryOperator &I) {
907 assert(I.getOpcode() == Instruction::LShr);
908
909 Value *Add = I.getOperand(0);
910 Value *ShiftAmt = I.getOperand(1);
911 Type *Ty = I.getType();
912
913 if (Ty->getScalarSizeInBits() < 3)
914 return nullptr;
915
916 const APInt *ShAmtAPInt = nullptr;
917 Value *X = nullptr, *Y = nullptr;
918 if (!match(ShiftAmt, m_APInt(ShAmtAPInt)) ||
919 !match(Add,
921 return nullptr;
922
923 const unsigned ShAmt = ShAmtAPInt->getZExtValue();
924 if (ShAmt == 1)
925 return nullptr;
926
927 // X/Y are zexts from `ShAmt`-sized ints.
928 if (X->getType()->getScalarSizeInBits() != ShAmt ||
929 Y->getType()->getScalarSizeInBits() != ShAmt)
930 return nullptr;
931
932 // Make sure that `Add` is only used by `I` and `ShAmt`-truncates.
933 if (!Add->hasOneUse()) {
934 for (User *U : Add->users()) {
935 if (U == &I)
936 continue;
937
938 TruncInst *Trunc = dyn_cast<TruncInst>(U);
939 if (!Trunc || Trunc->getType()->getScalarSizeInBits() > ShAmt)
940 return nullptr;
941 }
942 }
943
944 // Insert at Add so that the newly created `NarrowAdd` will dominate it's
945 // users (i.e. `Add`'s users).
946 Instruction *AddInst = cast<Instruction>(Add);
947 Builder.SetInsertPoint(AddInst);
948
949 Value *NarrowAdd = Builder.CreateAdd(X, Y, "add.narrowed");
950 Value *Overflow =
951 Builder.CreateICmpULT(NarrowAdd, X, "add.narrowed.overflow");
952
953 // Replace the uses of the original add with a zext of the
954 // NarrowAdd's result. Note that all users at this stage are known to
955 // be ShAmt-sized truncs, or the lshr itself.
956 if (!Add->hasOneUse()) {
957 replaceInstUsesWith(*AddInst, Builder.CreateZExt(NarrowAdd, Ty));
958 eraseInstFromFunction(*AddInst);
959 }
960
961 // Replace the LShr with a zext of the overflow check.
962 return new ZExtInst(Overflow, Ty);
963}
964
965// Try to set nuw/nsw flags on shl or exact flag on lshr/ashr using knownbits.
967 assert(I.isShift() && "Expected a shift as input");
968 // We already have all the flags.
969 if (I.getOpcode() == Instruction::Shl) {
970 if (I.hasNoUnsignedWrap() && I.hasNoSignedWrap())
971 return false;
972 } else {
973 if (I.isExact())
974 return false;
975
976 // shr (shl X, Y), Y
977 if (match(I.getOperand(0), m_Shl(m_Value(), m_Specific(I.getOperand(1))))) {
978 I.setIsExact();
979 return true;
980 }
981 }
982
983 // Compute what we know about shift count.
984 KnownBits KnownCnt = computeKnownBits(I.getOperand(1), /* Depth */ 0, Q);
985 unsigned BitWidth = KnownCnt.getBitWidth();
986 // Since shift produces a poison value if RHS is equal to or larger than the
987 // bit width, we can safely assume that RHS is less than the bit width.
988 uint64_t MaxCnt = KnownCnt.getMaxValue().getLimitedValue(BitWidth - 1);
989
990 KnownBits KnownAmt = computeKnownBits(I.getOperand(0), /* Depth */ 0, Q);
991 bool Changed = false;
992
993 if (I.getOpcode() == Instruction::Shl) {
994 // If we have as many leading zeros than maximum shift cnt we have nuw.
995 if (!I.hasNoUnsignedWrap() && MaxCnt <= KnownAmt.countMinLeadingZeros()) {
996 I.setHasNoUnsignedWrap();
997 Changed = true;
998 }
999 // If we have more sign bits than maximum shift cnt we have nsw.
1000 if (!I.hasNoSignedWrap()) {
1001 if (MaxCnt < KnownAmt.countMinSignBits() ||
1002 MaxCnt < ComputeNumSignBits(I.getOperand(0), Q.DL, /*Depth*/ 0, Q.AC,
1003 Q.CxtI, Q.DT)) {
1004 I.setHasNoSignedWrap();
1005 Changed = true;
1006 }
1007 }
1008 return Changed;
1009 }
1010
1011 // If we have at least as many trailing zeros as maximum count then we have
1012 // exact.
1013 Changed = MaxCnt <= KnownAmt.countMinTrailingZeros();
1014 I.setIsExact(Changed);
1015
1016 return Changed;
1017}
1018
1021
1022 if (Value *V = simplifyShlInst(I.getOperand(0), I.getOperand(1),
1023 I.hasNoSignedWrap(), I.hasNoUnsignedWrap(), Q))
1024 return replaceInstUsesWith(I, V);
1025
1027 return X;
1028
1030 return V;
1031
1033 return V;
1034
1035 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1036 Type *Ty = I.getType();
1037 unsigned BitWidth = Ty->getScalarSizeInBits();
1038
1039 const APInt *C;
1040 if (match(Op1, m_APInt(C))) {
1041 unsigned ShAmtC = C->getZExtValue();
1042
1043 // shl (zext X), C --> zext (shl X, C)
1044 // This is only valid if X would have zeros shifted out.
1045 Value *X;
1046 if (match(Op0, m_OneUse(m_ZExt(m_Value(X))))) {
1047 unsigned SrcWidth = X->getType()->getScalarSizeInBits();
1048 if (ShAmtC < SrcWidth &&
1049 MaskedValueIsZero(X, APInt::getHighBitsSet(SrcWidth, ShAmtC), 0, &I))
1050 return new ZExtInst(Builder.CreateShl(X, ShAmtC), Ty);
1051 }
1052
1053 // (X >> C) << C --> X & (-1 << C)
1054 if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1)))) {
1056 return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
1057 }
1058
1059 const APInt *C1;
1060 if (match(Op0, m_Exact(m_Shr(m_Value(X), m_APInt(C1)))) &&
1061 C1->ult(BitWidth)) {
1062 unsigned ShrAmt = C1->getZExtValue();
1063 if (ShrAmt < ShAmtC) {
1064 // If C1 < C: (X >>?,exact C1) << C --> X << (C - C1)
1065 Constant *ShiftDiff = ConstantInt::get(Ty, ShAmtC - ShrAmt);
1066 auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
1067 NewShl->setHasNoUnsignedWrap(
1068 I.hasNoUnsignedWrap() ||
1069 (ShrAmt &&
1070 cast<Instruction>(Op0)->getOpcode() == Instruction::LShr &&
1071 I.hasNoSignedWrap()));
1072 NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
1073 return NewShl;
1074 }
1075 if (ShrAmt > ShAmtC) {
1076 // If C1 > C: (X >>?exact C1) << C --> X >>?exact (C1 - C)
1077 Constant *ShiftDiff = ConstantInt::get(Ty, ShrAmt - ShAmtC);
1078 auto *NewShr = BinaryOperator::Create(
1079 cast<BinaryOperator>(Op0)->getOpcode(), X, ShiftDiff);
1080 NewShr->setIsExact(true);
1081 return NewShr;
1082 }
1083 }
1084
1085 if (match(Op0, m_OneUse(m_Shr(m_Value(X), m_APInt(C1)))) &&
1086 C1->ult(BitWidth)) {
1087 unsigned ShrAmt = C1->getZExtValue();
1088 if (ShrAmt < ShAmtC) {
1089 // If C1 < C: (X >>? C1) << C --> (X << (C - C1)) & (-1 << C)
1090 Constant *ShiftDiff = ConstantInt::get(Ty, ShAmtC - ShrAmt);
1091 auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
1092 NewShl->setHasNoUnsignedWrap(
1093 I.hasNoUnsignedWrap() ||
1094 (ShrAmt &&
1095 cast<Instruction>(Op0)->getOpcode() == Instruction::LShr &&
1096 I.hasNoSignedWrap()));
1097 NewShl->setHasNoSignedWrap(I.hasNoSignedWrap());
1098 Builder.Insert(NewShl);
1100 return BinaryOperator::CreateAnd(NewShl, ConstantInt::get(Ty, Mask));
1101 }
1102 if (ShrAmt > ShAmtC) {
1103 // If C1 > C: (X >>? C1) << C --> (X >>? (C1 - C)) & (-1 << C)
1104 Constant *ShiftDiff = ConstantInt::get(Ty, ShrAmt - ShAmtC);
1105 auto *OldShr = cast<BinaryOperator>(Op0);
1106 auto *NewShr =
1107 BinaryOperator::Create(OldShr->getOpcode(), X, ShiftDiff);
1108 NewShr->setIsExact(OldShr->isExact());
1109 Builder.Insert(NewShr);
1111 return BinaryOperator::CreateAnd(NewShr, ConstantInt::get(Ty, Mask));
1112 }
1113 }
1114
1115 // Similar to above, but look through an intermediate trunc instruction.
1116 BinaryOperator *Shr;
1117 if (match(Op0, m_OneUse(m_Trunc(m_OneUse(m_BinOp(Shr))))) &&
1118 match(Shr, m_Shr(m_Value(X), m_APInt(C1)))) {
1119 // The larger shift direction survives through the transform.
1120 unsigned ShrAmtC = C1->getZExtValue();
1121 unsigned ShDiff = ShrAmtC > ShAmtC ? ShrAmtC - ShAmtC : ShAmtC - ShrAmtC;
1122 Constant *ShiftDiffC = ConstantInt::get(X->getType(), ShDiff);
1123 auto ShiftOpc = ShrAmtC > ShAmtC ? Shr->getOpcode() : Instruction::Shl;
1124
1125 // If C1 > C:
1126 // (trunc (X >> C1)) << C --> (trunc (X >> (C1 - C))) && (-1 << C)
1127 // If C > C1:
1128 // (trunc (X >> C1)) << C --> (trunc (X << (C - C1))) && (-1 << C)
1129 Value *NewShift = Builder.CreateBinOp(ShiftOpc, X, ShiftDiffC, "sh.diff");
1130 Value *Trunc = Builder.CreateTrunc(NewShift, Ty, "tr.sh.diff");
1132 return BinaryOperator::CreateAnd(Trunc, ConstantInt::get(Ty, Mask));
1133 }
1134
1135 // If we have an opposite shift by the same amount, we may be able to
1136 // reorder binops and shifts to eliminate math/logic.
1137 auto isSuitableBinOpcode = [](Instruction::BinaryOps BinOpcode) {
1138 switch (BinOpcode) {
1139 default:
1140 return false;
1141 case Instruction::Add:
1142 case Instruction::And:
1143 case Instruction::Or:
1144 case Instruction::Xor:
1145 case Instruction::Sub:
1146 // NOTE: Sub is not commutable and the tranforms below may not be valid
1147 // when the shift-right is operand 1 (RHS) of the sub.
1148 return true;
1149 }
1150 };
1151 BinaryOperator *Op0BO;
1152 if (match(Op0, m_OneUse(m_BinOp(Op0BO))) &&
1153 isSuitableBinOpcode(Op0BO->getOpcode())) {
1154 // Commute so shift-right is on LHS of the binop.
1155 // (Y bop (X >> C)) << C -> ((X >> C) bop Y) << C
1156 // (Y bop ((X >> C) & CC)) << C -> (((X >> C) & CC) bop Y) << C
1157 Value *Shr = Op0BO->getOperand(0);
1158 Value *Y = Op0BO->getOperand(1);
1159 Value *X;
1160 const APInt *CC;
1161 if (Op0BO->isCommutative() && Y->hasOneUse() &&
1162 (match(Y, m_Shr(m_Value(), m_Specific(Op1))) ||
1164 m_APInt(CC)))))
1165 std::swap(Shr, Y);
1166
1167 // ((X >> C) bop Y) << C -> (X bop (Y << C)) & (~0 << C)
1168 if (match(Shr, m_OneUse(m_Shr(m_Value(X), m_Specific(Op1))))) {
1169 // Y << C
1170 Value *YS = Builder.CreateShl(Y, Op1, Op0BO->getName());
1171 // (X bop (Y << C))
1172 Value *B =
1173 Builder.CreateBinOp(Op0BO->getOpcode(), X, YS, Shr->getName());
1174 unsigned Op1Val = C->getLimitedValue(BitWidth);
1175 APInt Bits = APInt::getHighBitsSet(BitWidth, BitWidth - Op1Val);
1176 Constant *Mask = ConstantInt::get(Ty, Bits);
1177 return BinaryOperator::CreateAnd(B, Mask);
1178 }
1179
1180 // (((X >> C) & CC) bop Y) << C -> (X & (CC << C)) bop (Y << C)
1181 if (match(Shr,
1183 m_APInt(CC))))) {
1184 // Y << C
1185 Value *YS = Builder.CreateShl(Y, Op1, Op0BO->getName());
1186 // X & (CC << C)
1187 Value *M = Builder.CreateAnd(X, ConstantInt::get(Ty, CC->shl(*C)),
1188 X->getName() + ".mask");
1189 auto *NewOp = BinaryOperator::Create(Op0BO->getOpcode(), M, YS);
1190 if (auto *Disjoint = dyn_cast<PossiblyDisjointInst>(Op0BO);
1191 Disjoint && Disjoint->isDisjoint())
1192 cast<PossiblyDisjointInst>(NewOp)->setIsDisjoint(true);
1193 return NewOp;
1194 }
1195 }
1196
1197 // (C1 - X) << C --> (C1 << C) - (X << C)
1198 if (match(Op0, m_OneUse(m_Sub(m_APInt(C1), m_Value(X))))) {
1199 Constant *NewLHS = ConstantInt::get(Ty, C1->shl(*C));
1200 Value *NewShift = Builder.CreateShl(X, Op1);
1201 return BinaryOperator::CreateSub(NewLHS, NewShift);
1202 }
1203 }
1204
1205 if (setShiftFlags(I, Q))
1206 return &I;
1207
1208 // Transform (x >> y) << y to x & (-1 << y)
1209 // Valid for any type of right-shift.
1210 Value *X;
1211 if (match(Op0, m_OneUse(m_Shr(m_Value(X), m_Specific(Op1))))) {
1213 Value *Mask = Builder.CreateShl(AllOnes, Op1);
1214 return BinaryOperator::CreateAnd(Mask, X);
1215 }
1216
1217 // Transform (-1 >> y) << y to -1 << y
1218 if (match(Op0, m_LShr(m_AllOnes(), m_Specific(Op1)))) {
1220 return BinaryOperator::CreateShl(AllOnes, Op1);
1221 }
1222
1223 Constant *C1;
1224 if (match(Op1, m_ImmConstant(C1))) {
1225 Constant *C2;
1226 Value *X;
1227 // (X * C2) << C1 --> X * (C2 << C1)
1228 if (match(Op0, m_Mul(m_Value(X), m_ImmConstant(C2))))
1229 return BinaryOperator::CreateMul(X, Builder.CreateShl(C2, C1));
1230
1231 // shl (zext i1 X), C1 --> select (X, 1 << C1, 0)
1232 if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
1233 auto *NewC = Builder.CreateShl(ConstantInt::get(Ty, 1), C1);
1235 }
1236 }
1237
1238 if (match(Op0, m_One())) {
1239 // (1 << (C - x)) -> ((1 << C) >> x) if C is bitwidth - 1
1240 if (match(Op1, m_Sub(m_SpecificInt(BitWidth - 1), m_Value(X))))
1241 return BinaryOperator::CreateLShr(
1242 ConstantInt::get(Ty, APInt::getSignMask(BitWidth)), X);
1243
1244 // Canonicalize "extract lowest set bit" using cttz to and-with-negate:
1245 // 1 << (cttz X) --> -X & X
1246 if (match(Op1,
1247 m_OneUse(m_Intrinsic<Intrinsic::cttz>(m_Value(X), m_Value())))) {
1248 Value *NegX = Builder.CreateNeg(X, "neg");
1249 return BinaryOperator::CreateAnd(NegX, X);
1250 }
1251 }
1252
1253 return nullptr;
1254}
1255
1257 if (Value *V = simplifyLShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
1259 return replaceInstUsesWith(I, V);
1260
1262 return X;
1263
1265 return R;
1266
1267 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1268 Type *Ty = I.getType();
1269 Value *X;
1270 const APInt *C;
1271 unsigned BitWidth = Ty->getScalarSizeInBits();
1272
1273 // (iN (~X) u>> (N - 1)) --> zext (X > -1)
1274 if (match(Op0, m_OneUse(m_Not(m_Value(X)))) &&
1276 return new ZExtInst(Builder.CreateIsNotNeg(X, "isnotneg"), Ty);
1277
1278 // ((X << nuw Z) sub nuw Y) >>u exact Z --> X sub nuw (Y >>u exact Z)
1279 Value *Y;
1280 if (I.isExact() &&
1282 m_Value(Y))))) {
1283 Value *NewLshr = Builder.CreateLShr(Y, Op1, "", /*isExact=*/true);
1284 auto *NewSub = BinaryOperator::CreateNUWSub(X, NewLshr);
1285 NewSub->setHasNoSignedWrap(
1286 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap());
1287 return NewSub;
1288 }
1289
1290 // Fold (X + Y) / 2 --> (X & Y) iff (X u<= 1) && (Y u<= 1)
1291 if (match(Op0, m_Add(m_Value(X), m_Value(Y))) && match(Op1, m_One()) &&
1292 computeKnownBits(X, /*Depth=*/0, &I).countMaxActiveBits() <= 1 &&
1293 computeKnownBits(Y, /*Depth=*/0, &I).countMaxActiveBits() <= 1)
1294 return BinaryOperator::CreateAnd(X, Y);
1295
1296 // (sub nuw X, (Y << nuw Z)) >>u exact Z --> (X >>u exact Z) sub nuw Y
1297 if (I.isExact() &&
1299 m_NUWShl(m_Value(Y), m_Specific(Op1)))))) {
1300 Value *NewLshr = Builder.CreateLShr(X, Op1, "", /*isExact=*/true);
1301 auto *NewSub = BinaryOperator::CreateNUWSub(NewLshr, Y);
1302 NewSub->setHasNoSignedWrap(
1303 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap());
1304 return NewSub;
1305 }
1306
1307 auto isSuitableBinOpcode = [](Instruction::BinaryOps BinOpcode) {
1308 switch (BinOpcode) {
1309 default:
1310 return false;
1311 case Instruction::Add:
1312 case Instruction::And:
1313 case Instruction::Or:
1314 case Instruction::Xor:
1315 // Sub is handled separately.
1316 return true;
1317 }
1318 };
1319
1320 // If both the binop and the shift are nuw, then:
1321 // ((X << nuw Z) binop nuw Y) >>u Z --> X binop nuw (Y >>u Z)
1323 m_Value(Y))))) {
1324 BinaryOperator *Op0OB = cast<BinaryOperator>(Op0);
1325 if (isSuitableBinOpcode(Op0OB->getOpcode())) {
1326 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op0);
1327 !OBO || OBO->hasNoUnsignedWrap()) {
1328 Value *NewLshr = Builder.CreateLShr(
1329 Y, Op1, "", I.isExact() && Op0OB->getOpcode() != Instruction::And);
1330 auto *NewBinOp = BinaryOperator::Create(Op0OB->getOpcode(), NewLshr, X);
1331 if (OBO) {
1332 NewBinOp->setHasNoUnsignedWrap(true);
1333 NewBinOp->setHasNoSignedWrap(OBO->hasNoSignedWrap());
1334 } else if (auto *Disjoint = dyn_cast<PossiblyDisjointInst>(Op0)) {
1335 cast<PossiblyDisjointInst>(NewBinOp)->setIsDisjoint(
1336 Disjoint->isDisjoint());
1337 }
1338 return NewBinOp;
1339 }
1340 }
1341 }
1342
1343 if (match(Op1, m_APInt(C))) {
1344 unsigned ShAmtC = C->getZExtValue();
1345 auto *II = dyn_cast<IntrinsicInst>(Op0);
1346 if (II && isPowerOf2_32(BitWidth) && Log2_32(BitWidth) == ShAmtC &&
1347 (II->getIntrinsicID() == Intrinsic::ctlz ||
1348 II->getIntrinsicID() == Intrinsic::cttz ||
1349 II->getIntrinsicID() == Intrinsic::ctpop)) {
1350 // ctlz.i32(x)>>5 --> zext(x == 0)
1351 // cttz.i32(x)>>5 --> zext(x == 0)
1352 // ctpop.i32(x)>>5 --> zext(x == -1)
1353 bool IsPop = II->getIntrinsicID() == Intrinsic::ctpop;
1354 Constant *RHS = ConstantInt::getSigned(Ty, IsPop ? -1 : 0);
1355 Value *Cmp = Builder.CreateICmpEQ(II->getArgOperand(0), RHS);
1356 return new ZExtInst(Cmp, Ty);
1357 }
1358
1359 const APInt *C1;
1360 if (match(Op0, m_Shl(m_Value(X), m_APInt(C1))) && C1->ult(BitWidth)) {
1361 if (C1->ult(ShAmtC)) {
1362 unsigned ShlAmtC = C1->getZExtValue();
1363 Constant *ShiftDiff = ConstantInt::get(Ty, ShAmtC - ShlAmtC);
1364 if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
1365 // (X <<nuw C1) >>u C --> X >>u (C - C1)
1366 auto *NewLShr = BinaryOperator::CreateLShr(X, ShiftDiff);
1367 NewLShr->setIsExact(I.isExact());
1368 return NewLShr;
1369 }
1370 if (Op0->hasOneUse()) {
1371 // (X << C1) >>u C --> (X >>u (C - C1)) & (-1 >> C)
1372 Value *NewLShr = Builder.CreateLShr(X, ShiftDiff, "", I.isExact());
1374 return BinaryOperator::CreateAnd(NewLShr, ConstantInt::get(Ty, Mask));
1375 }
1376 } else if (C1->ugt(ShAmtC)) {
1377 unsigned ShlAmtC = C1->getZExtValue();
1378 Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmtC - ShAmtC);
1379 if (cast<BinaryOperator>(Op0)->hasNoUnsignedWrap()) {
1380 // (X <<nuw C1) >>u C --> X <<nuw/nsw (C1 - C)
1381 auto *NewShl = BinaryOperator::CreateShl(X, ShiftDiff);
1382 NewShl->setHasNoUnsignedWrap(true);
1383 NewShl->setHasNoSignedWrap(ShAmtC > 0);
1384 return NewShl;
1385 }
1386 if (Op0->hasOneUse()) {
1387 // (X << C1) >>u C --> X << (C1 - C) & (-1 >> C)
1388 Value *NewShl = Builder.CreateShl(X, ShiftDiff);
1390 return BinaryOperator::CreateAnd(NewShl, ConstantInt::get(Ty, Mask));
1391 }
1392 } else {
1393 assert(*C1 == ShAmtC);
1394 // (X << C) >>u C --> X & (-1 >>u C)
1396 return BinaryOperator::CreateAnd(X, ConstantInt::get(Ty, Mask));
1397 }
1398 }
1399
1400 // ((X << C) + Y) >>u C --> (X + (Y >>u C)) & (-1 >>u C)
1401 // TODO: Consolidate with the more general transform that starts from shl
1402 // (the shifts are in the opposite order).
1403 if (match(Op0,
1405 m_Value(Y))))) {
1406 Value *NewLshr = Builder.CreateLShr(Y, Op1);
1407 Value *NewAdd = Builder.CreateAdd(NewLshr, X);
1408 unsigned Op1Val = C->getLimitedValue(BitWidth);
1409 APInt Bits = APInt::getLowBitsSet(BitWidth, BitWidth - Op1Val);
1410 Constant *Mask = ConstantInt::get(Ty, Bits);
1411 return BinaryOperator::CreateAnd(NewAdd, Mask);
1412 }
1413
1414 if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) &&
1415 (!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType()))) {
1416 assert(ShAmtC < X->getType()->getScalarSizeInBits() &&
1417 "Big shift not simplified to zero?");
1418 // lshr (zext iM X to iN), C --> zext (lshr X, C) to iN
1419 Value *NewLShr = Builder.CreateLShr(X, ShAmtC);
1420 return new ZExtInst(NewLShr, Ty);
1421 }
1422
1423 if (match(Op0, m_SExt(m_Value(X)))) {
1424 unsigned SrcTyBitWidth = X->getType()->getScalarSizeInBits();
1425 // lshr (sext i1 X to iN), C --> select (X, -1 >> C, 0)
1426 if (SrcTyBitWidth == 1) {
1427 auto *NewC = ConstantInt::get(
1428 Ty, APInt::getLowBitsSet(BitWidth, BitWidth - ShAmtC));
1430 }
1431
1432 if ((!Ty->isIntegerTy() || shouldChangeType(Ty, X->getType())) &&
1433 Op0->hasOneUse()) {
1434 // Are we moving the sign bit to the low bit and widening with high
1435 // zeros? lshr (sext iM X to iN), N-1 --> zext (lshr X, M-1) to iN
1436 if (ShAmtC == BitWidth - 1) {
1437 Value *NewLShr = Builder.CreateLShr(X, SrcTyBitWidth - 1);
1438 return new ZExtInst(NewLShr, Ty);
1439 }
1440
1441 // lshr (sext iM X to iN), N-M --> zext (ashr X, min(N-M, M-1)) to iN
1442 if (ShAmtC == BitWidth - SrcTyBitWidth) {
1443 // The new shift amount can't be more than the narrow source type.
1444 unsigned NewShAmt = std::min(ShAmtC, SrcTyBitWidth - 1);
1445 Value *AShr = Builder.CreateAShr(X, NewShAmt);
1446 return new ZExtInst(AShr, Ty);
1447 }
1448 }
1449 }
1450
1451 if (ShAmtC == BitWidth - 1) {
1452 // lshr i32 or(X,-X), 31 --> zext (X != 0)
1453 if (match(Op0, m_OneUse(m_c_Or(m_Neg(m_Value(X)), m_Deferred(X)))))
1454 return new ZExtInst(Builder.CreateIsNotNull(X), Ty);
1455
1456 // lshr i32 (X -nsw Y), 31 --> zext (X < Y)
1457 if (match(Op0, m_OneUse(m_NSWSub(m_Value(X), m_Value(Y)))))
1458 return new ZExtInst(Builder.CreateICmpSLT(X, Y), Ty);
1459
1460 // Check if a number is negative and odd:
1461 // lshr i32 (srem X, 2), 31 --> and (X >> 31), X
1462 if (match(Op0, m_OneUse(m_SRem(m_Value(X), m_SpecificInt(2))))) {
1463 Value *Signbit = Builder.CreateLShr(X, ShAmtC);
1464 return BinaryOperator::CreateAnd(Signbit, X);
1465 }
1466 }
1467
1468 Instruction *TruncSrc;
1469 if (match(Op0, m_OneUse(m_Trunc(m_Instruction(TruncSrc)))) &&
1470 match(TruncSrc, m_LShr(m_Value(X), m_APInt(C1)))) {
1471 unsigned SrcWidth = X->getType()->getScalarSizeInBits();
1472 unsigned AmtSum = ShAmtC + C1->getZExtValue();
1473
1474 // If the combined shift fits in the source width:
1475 // (trunc (X >>u C1)) >>u C --> and (trunc (X >>u (C1 + C)), MaskC
1476 //
1477 // If the first shift covers the number of bits truncated, then the
1478 // mask instruction is eliminated (and so the use check is relaxed).
1479 if (AmtSum < SrcWidth &&
1480 (TruncSrc->hasOneUse() || C1->uge(SrcWidth - BitWidth))) {
1481 Value *SumShift = Builder.CreateLShr(X, AmtSum, "sum.shift");
1482 Value *Trunc = Builder.CreateTrunc(SumShift, Ty, I.getName());
1483
1484 // If the first shift does not cover the number of bits truncated, then
1485 // we require a mask to get rid of high bits in the result.
1486 APInt MaskC = APInt::getAllOnes(BitWidth).lshr(ShAmtC);
1487 return BinaryOperator::CreateAnd(Trunc, ConstantInt::get(Ty, MaskC));
1488 }
1489 }
1490
1491 const APInt *MulC;
1492 if (match(Op0, m_NUWMul(m_Value(X), m_APInt(MulC)))) {
1493 if (BitWidth > 2 && (*MulC - 1).isPowerOf2() &&
1494 MulC->logBase2() == ShAmtC) {
1495 // Look for a "splat" mul pattern - it replicates bits across each half
1496 // of a value, so a right shift simplifies back to just X:
1497 // lshr i[2N] (mul nuw X, (2^N)+1), N --> X
1498 if (ShAmtC * 2 == BitWidth)
1499 return replaceInstUsesWith(I, X);
1500
1501 // lshr (mul nuw (X, 2^N + 1)), N -> add nuw (X, lshr(X, N))
1502 if (Op0->hasOneUse()) {
1503 auto *NewAdd = BinaryOperator::CreateNUWAdd(
1504 X, Builder.CreateLShr(X, ConstantInt::get(Ty, ShAmtC), "",
1505 I.isExact()));
1506 NewAdd->setHasNoSignedWrap(
1507 cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap());
1508 return NewAdd;
1509 }
1510 }
1511
1512 // The one-use check is not strictly necessary, but codegen may not be
1513 // able to invert the transform and perf may suffer with an extra mul
1514 // instruction.
1515 if (Op0->hasOneUse()) {
1516 APInt NewMulC = MulC->lshr(ShAmtC);
1517 // if c is divisible by (1 << ShAmtC):
1518 // lshr (mul nuw x, MulC), ShAmtC -> mul nuw nsw x, (MulC >> ShAmtC)
1519 if (MulC->eq(NewMulC.shl(ShAmtC))) {
1520 auto *NewMul =
1521 BinaryOperator::CreateNUWMul(X, ConstantInt::get(Ty, NewMulC));
1522 assert(ShAmtC != 0 &&
1523 "lshr X, 0 should be handled by simplifyLShrInst.");
1524 NewMul->setHasNoSignedWrap(true);
1525 return NewMul;
1526 }
1527 }
1528 }
1529
1530 // lshr (mul nsw (X, 2^N + 1)), N -> add nsw (X, lshr(X, N))
1531 if (match(Op0, m_OneUse(m_NSWMul(m_Value(X), m_APInt(MulC))))) {
1532 if (BitWidth > 2 && (*MulC - 1).isPowerOf2() &&
1533 MulC->logBase2() == ShAmtC) {
1534 return BinaryOperator::CreateNSWAdd(
1535 X, Builder.CreateLShr(X, ConstantInt::get(Ty, ShAmtC), "",
1536 I.isExact()));
1537 }
1538 }
1539
1540 // Try to narrow bswap.
1541 // In the case where the shift amount equals the bitwidth difference, the
1542 // shift is eliminated.
1543 if (match(Op0, m_OneUse(m_Intrinsic<Intrinsic::bswap>(
1544 m_OneUse(m_ZExt(m_Value(X))))))) {
1545 unsigned SrcWidth = X->getType()->getScalarSizeInBits();
1546 unsigned WidthDiff = BitWidth - SrcWidth;
1547 if (SrcWidth % 16 == 0) {
1548 Value *NarrowSwap = Builder.CreateUnaryIntrinsic(Intrinsic::bswap, X);
1549 if (ShAmtC >= WidthDiff) {
1550 // (bswap (zext X)) >> C --> zext (bswap X >> C')
1551 Value *NewShift = Builder.CreateLShr(NarrowSwap, ShAmtC - WidthDiff);
1552 return new ZExtInst(NewShift, Ty);
1553 } else {
1554 // (bswap (zext X)) >> C --> (zext (bswap X)) << C'
1555 Value *NewZExt = Builder.CreateZExt(NarrowSwap, Ty);
1556 Constant *ShiftDiff = ConstantInt::get(Ty, WidthDiff - ShAmtC);
1557 return BinaryOperator::CreateShl(NewZExt, ShiftDiff);
1558 }
1559 }
1560 }
1561
1562 // Reduce add-carry of bools to logic:
1563 // ((zext BoolX) + (zext BoolY)) >> 1 --> zext (BoolX && BoolY)
1564 Value *BoolX, *BoolY;
1565 if (ShAmtC == 1 && match(Op0, m_Add(m_Value(X), m_Value(Y))) &&
1566 match(X, m_ZExt(m_Value(BoolX))) && match(Y, m_ZExt(m_Value(BoolY))) &&
1567 BoolX->getType()->isIntOrIntVectorTy(1) &&
1568 BoolY->getType()->isIntOrIntVectorTy(1) &&
1569 (X->hasOneUse() || Y->hasOneUse() || Op0->hasOneUse())) {
1570 Value *And = Builder.CreateAnd(BoolX, BoolY);
1571 return new ZExtInst(And, Ty);
1572 }
1573 }
1574
1576 if (setShiftFlags(I, Q))
1577 return &I;
1578
1579 // Transform (x << y) >> y to x & (-1 >> y)
1580 if (match(Op0, m_OneUse(m_Shl(m_Value(X), m_Specific(Op1))))) {
1582 Value *Mask = Builder.CreateLShr(AllOnes, Op1);
1583 return BinaryOperator::CreateAnd(Mask, X);
1584 }
1585
1586 // Transform (-1 << y) >> y to -1 >> y
1587 if (match(Op0, m_Shl(m_AllOnes(), m_Specific(Op1)))) {
1589 return BinaryOperator::CreateLShr(AllOnes, Op1);
1590 }
1591
1592 if (Instruction *Overflow = foldLShrOverflowBit(I))
1593 return Overflow;
1594
1595 return nullptr;
1596}
1597
1600 BinaryOperator &OldAShr) {
1601 assert(OldAShr.getOpcode() == Instruction::AShr &&
1602 "Must be called with arithmetic right-shift instruction only.");
1603
1604 // Check that constant C is a splat of the element-wise bitwidth of V.
1605 auto BitWidthSplat = [](Constant *C, Value *V) {
1606 return match(
1608 APInt(C->getType()->getScalarSizeInBits(),
1609 V->getType()->getScalarSizeInBits())));
1610 };
1611
1612 // It should look like variable-length sign-extension on the outside:
1613 // (Val << (bitwidth(Val)-Nbits)) a>> (bitwidth(Val)-Nbits)
1614 Value *NBits;
1615 Instruction *MaybeTrunc;
1616 Constant *C1, *C2;
1617 if (!match(&OldAShr,
1618 m_AShr(m_Shl(m_Instruction(MaybeTrunc),
1620 m_ZExtOrSelf(m_Value(NBits))))),
1622 m_ZExtOrSelf(m_Deferred(NBits)))))) ||
1623 !BitWidthSplat(C1, &OldAShr) || !BitWidthSplat(C2, &OldAShr))
1624 return nullptr;
1625
1626 // There may or may not be a truncation after outer two shifts.
1627 Instruction *HighBitExtract;
1628 match(MaybeTrunc, m_TruncOrSelf(m_Instruction(HighBitExtract)));
1629 bool HadTrunc = MaybeTrunc != HighBitExtract;
1630
1631 // And finally, the innermost part of the pattern must be a right-shift.
1632 Value *X, *NumLowBitsToSkip;
1633 if (!match(HighBitExtract, m_Shr(m_Value(X), m_Value(NumLowBitsToSkip))))
1634 return nullptr;
1635
1636 // Said right-shift must extract high NBits bits - C0 must be it's bitwidth.
1637 Constant *C0;
1638 if (!match(NumLowBitsToSkip,
1640 m_Sub(m_Constant(C0), m_ZExtOrSelf(m_Specific(NBits))))) ||
1641 !BitWidthSplat(C0, HighBitExtract))
1642 return nullptr;
1643
1644 // Since the NBits is identical for all shifts, if the outermost and
1645 // innermost shifts are identical, then outermost shifts are redundant.
1646 // If we had truncation, do keep it though.
1647 if (HighBitExtract->getOpcode() == OldAShr.getOpcode())
1648 return replaceInstUsesWith(OldAShr, MaybeTrunc);
1649
1650 // Else, if there was a truncation, then we need to ensure that one
1651 // instruction will go away.
1652 if (HadTrunc && !match(&OldAShr, m_c_BinOp(m_OneUse(m_Value()), m_Value())))
1653 return nullptr;
1654
1655 // Finally, bypass two innermost shifts, and perform the outermost shift on
1656 // the operands of the innermost shift.
1657 Instruction *NewAShr =
1658 BinaryOperator::Create(OldAShr.getOpcode(), X, NumLowBitsToSkip);
1659 NewAShr->copyIRFlags(HighBitExtract); // We can preserve 'exact'-ness.
1660 if (!HadTrunc)
1661 return NewAShr;
1662
1663 Builder.Insert(NewAShr);
1664 return TruncInst::CreateTruncOrBitCast(NewAShr, OldAShr.getType());
1665}
1666
1668 if (Value *V = simplifyAShrInst(I.getOperand(0), I.getOperand(1), I.isExact(),
1670 return replaceInstUsesWith(I, V);
1671
1673 return X;
1674
1676 return R;
1677
1678 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
1679 Type *Ty = I.getType();
1680 unsigned BitWidth = Ty->getScalarSizeInBits();
1681 const APInt *ShAmtAPInt;
1682 if (match(Op1, m_APInt(ShAmtAPInt)) && ShAmtAPInt->ult(BitWidth)) {
1683 unsigned ShAmt = ShAmtAPInt->getZExtValue();
1684
1685 // If the shift amount equals the difference in width of the destination
1686 // and source scalar types:
1687 // ashr (shl (zext X), C), C --> sext X
1688 Value *X;
1689 if (match(Op0, m_Shl(m_ZExt(m_Value(X)), m_Specific(Op1))) &&
1690 ShAmt == BitWidth - X->getType()->getScalarSizeInBits())
1691 return new SExtInst(X, Ty);
1692
1693 // We can't handle (X << C1) >>s C2. It shifts arbitrary bits in. However,
1694 // we can handle (X <<nsw C1) >>s C2 since it only shifts in sign bits.
1695 const APInt *ShOp1;
1696 if (match(Op0, m_NSWShl(m_Value(X), m_APInt(ShOp1))) &&
1697 ShOp1->ult(BitWidth)) {
1698 unsigned ShlAmt = ShOp1->getZExtValue();
1699 if (ShlAmt < ShAmt) {
1700 // (X <<nsw C1) >>s C2 --> X >>s (C2 - C1)
1701 Constant *ShiftDiff = ConstantInt::get(Ty, ShAmt - ShlAmt);
1702 auto *NewAShr = BinaryOperator::CreateAShr(X, ShiftDiff);
1703 NewAShr->setIsExact(I.isExact());
1704 return NewAShr;
1705 }
1706 if (ShlAmt > ShAmt) {
1707 // (X <<nsw C1) >>s C2 --> X <<nsw (C1 - C2)
1708 Constant *ShiftDiff = ConstantInt::get(Ty, ShlAmt - ShAmt);
1709 auto *NewShl = BinaryOperator::Create(Instruction::Shl, X, ShiftDiff);
1710 NewShl->setHasNoSignedWrap(true);
1711 return NewShl;
1712 }
1713 }
1714
1715 if (match(Op0, m_AShr(m_Value(X), m_APInt(ShOp1))) &&
1716 ShOp1->ult(BitWidth)) {
1717 unsigned AmtSum = ShAmt + ShOp1->getZExtValue();
1718 // Oversized arithmetic shifts replicate the sign bit.
1719 AmtSum = std::min(AmtSum, BitWidth - 1);
1720 // (X >>s C1) >>s C2 --> X >>s (C1 + C2)
1721 return BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
1722 }
1723
1724 if (match(Op0, m_OneUse(m_SExt(m_Value(X)))) &&
1725 (Ty->isVectorTy() || shouldChangeType(Ty, X->getType()))) {
1726 // ashr (sext X), C --> sext (ashr X, C')
1727 Type *SrcTy = X->getType();
1728 ShAmt = std::min(ShAmt, SrcTy->getScalarSizeInBits() - 1);
1729 Value *NewSh = Builder.CreateAShr(X, ConstantInt::get(SrcTy, ShAmt));
1730 return new SExtInst(NewSh, Ty);
1731 }
1732
1733 if (ShAmt == BitWidth - 1) {
1734 // ashr i32 or(X,-X), 31 --> sext (X != 0)
1735 if (match(Op0, m_OneUse(m_c_Or(m_Neg(m_Value(X)), m_Deferred(X)))))
1736 return new SExtInst(Builder.CreateIsNotNull(X), Ty);
1737
1738 // ashr i32 (X -nsw Y), 31 --> sext (X < Y)
1739 Value *Y;
1740 if (match(Op0, m_OneUse(m_NSWSub(m_Value(X), m_Value(Y)))))
1741 return new SExtInst(Builder.CreateICmpSLT(X, Y), Ty);
1742 }
1743
1744 const APInt *MulC;
1745 if (match(Op0, m_OneUse(m_NSWMul(m_Value(X), m_APInt(MulC)))) &&
1746 (BitWidth > 2 && (*MulC - 1).isPowerOf2() &&
1747 MulC->logBase2() == ShAmt &&
1748 (ShAmt < BitWidth - 1))) /* Minus 1 for the sign bit */ {
1749
1750 // ashr (mul nsw (X, 2^N + 1)), N -> add nsw (X, ashr(X, N))
1751 auto *NewAdd = BinaryOperator::CreateNSWAdd(
1752 X,
1753 Builder.CreateAShr(X, ConstantInt::get(Ty, ShAmt), "", I.isExact()));
1754 NewAdd->setHasNoUnsignedWrap(
1755 cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap());
1756 return NewAdd;
1757 }
1758 }
1759
1761 if (setShiftFlags(I, Q))
1762 return &I;
1763
1764 // Prefer `-(x & 1)` over `(x << (bitwidth(x)-1)) a>> (bitwidth(x)-1)`
1765 // as the pattern to splat the lowest bit.
1766 // FIXME: iff X is already masked, we don't need the one-use check.
1767 Value *X;
1768 if (match(Op1, m_SpecificIntAllowPoison(BitWidth - 1)) &&
1771 Constant *Mask = ConstantInt::get(Ty, 1);
1772 // Retain the knowledge about the ignored lanes.
1774 Constant::mergeUndefsWith(Mask, cast<Constant>(Op1)),
1775 cast<Constant>(cast<Instruction>(Op0)->getOperand(1)));
1776 X = Builder.CreateAnd(X, Mask);
1778 }
1779
1781 return R;
1782
1783 // See if we can turn a signed shr into an unsigned shr.
1785 Instruction *Lshr = BinaryOperator::CreateLShr(Op0, Op1);
1786 Lshr->setIsExact(I.isExact());
1787 return Lshr;
1788 }
1789
1790 // ashr (xor %x, -1), %y --> xor (ashr %x, %y), -1
1791 if (match(Op0, m_OneUse(m_Not(m_Value(X))))) {
1792 // Note that we must drop 'exact'-ness of the shift!
1793 // Note that we can't keep undef's in -1 vector constant!
1794 auto *NewAShr = Builder.CreateAShr(X, Op1, Op0->getName() + ".not");
1795 return BinaryOperator::CreateNot(NewAShr);
1796 }
1797
1798 return nullptr;
1799}
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
static GCRegistry::Add< ErlangGC > A("erlang", "erlang-compatible garbage collector")
#define LLVM_DEBUG(X)
Definition: Debug.h:101
uint64_t Size
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
This file provides internal interfaces used to implement the InstCombine.
static Value * foldShiftedShift(BinaryOperator *InnerShift, unsigned OuterShAmt, bool IsOuterShl, InstCombiner::BuilderTy &Builder)
Fold OuterShift (InnerShift X, C1), C2.
static bool setShiftFlags(BinaryOperator &I, const SimplifyQuery &Q)
static Instruction * dropRedundantMaskingOfLeftShiftInput(BinaryOperator *OuterShift, const SimplifyQuery &Q, InstCombiner::BuilderTy &Builder)
static bool canEvaluateShifted(Value *V, unsigned NumBits, bool IsLeftShift, InstCombinerImpl &IC, Instruction *CxtI)
See if we can compute the specified value, but shifted logically to the left or right by some number ...
bool canTryToConstantAddTwoShiftAmounts(Value *Sh0, Value *ShAmt0, Value *Sh1, Value *ShAmt1)
static Instruction * foldShiftOfShiftedBinOp(BinaryOperator &I, InstCombiner::BuilderTy &Builder)
If we have a shift-by-constant of a bin op (bitwise logic op or add/sub w/ shl) that itself has a shi...
static bool canEvaluateShiftedShift(unsigned OuterShAmt, bool IsOuterShl, Instruction *InnerShift, InstCombinerImpl &IC, Instruction *CxtI)
Return true if we can simplify two logical (either left or right) shifts that have constant shift amo...
static Value * getShiftedValue(Value *V, unsigned NumBits, bool isLeftShift, InstCombinerImpl &IC, const DataLayout &DL)
When canEvaluateShifted() returns true for an expression, this function inserts the new computation t...
static bool canShiftBinOpWithConstantRHS(BinaryOperator &Shift, BinaryOperator *BO)
This file provides the interface for the instcombine pass implementation.
static bool hasNoSignedWrap(BinaryOperator &I)
static bool hasNoUnsignedWrap(BinaryOperator &I)
#define I(x, y, z)
Definition: MD5.cpp:58
uint64_t IntrinsicInst * II
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
const SmallVectorImpl< MachineOperand > & Cond
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static const MCExpr * MaskShift(const MCExpr *Val, uint32_t Mask, uint32_t Shift, MCContext &Ctx)
static unsigned getScalarSizeInBits(Type *Ty)
static SymbolRef::Type getType(const Symbol *Sym)
Definition: TapiFile.cpp:40
static std::optional< unsigned > getOpcode(ArrayRef< VPValue * > Values)
Returns the opcode of Values or ~0 if they do not all agree.
Definition: VPlanSLP.cpp:191
Value * RHS
Class for arbitrary precision integers.
Definition: APInt.h:77
static APInt getAllOnes(unsigned numBits)
Return an APInt of a specified width with all bits set.
Definition: APInt.h:213
bool isNegatedPowerOf2() const
Check if this APInt's negated value is a power of two greater than zero.
Definition: APInt.h:428
static APInt getSignMask(unsigned BitWidth)
Get the SignMask for a specific bit width.
Definition: APInt.h:208
bool isMinSignedValue() const
Determine if this is the smallest signed value.
Definition: APInt.h:402
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1499
bool ugt(const APInt &RHS) const
Unsigned greater than comparison.
Definition: APInt.h:1161
bool isZero() const
Determine if this value is zero, i.e. all bits are clear.
Definition: APInt.h:359
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1090
bool isNegative() const
Determine sign of this APInt.
Definition: APInt.h:308
bool eq(const APInt &RHS) const
Equality comparison.
Definition: APInt.h:1058
unsigned countr_zero() const
Count the number of trailing zero bits.
Definition: APInt.h:1597
unsigned logBase2() const
Definition: APInt.h:1718
uint64_t getLimitedValue(uint64_t Limit=UINT64_MAX) const
If this value is smaller than the specified limit, return it, otherwise return the limit value.
Definition: APInt.h:454
APInt shl(unsigned shiftAmt) const
Left-shift function.
Definition: APInt.h:852
static APInt getLowBitsSet(unsigned numBits, unsigned loBitsSet)
Constructs an APInt value that has the bottom loBitsSet bits set.
Definition: APInt.h:285
static APInt getHighBitsSet(unsigned numBits, unsigned hiBitsSet)
Constructs an APInt value that has the top hiBitsSet bits set.
Definition: APInt.h:275
APInt lshr(unsigned shiftAmt) const
Logical right-shift function.
Definition: APInt.h:830
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1200
static BinaryOperator * CreateNeg(Value *Op, const Twine &Name="", InsertPosition InsertBefore=nullptr)
Helper functions to construct and inspect unary operations (NEG and NOT) via binary operators SUB and...
BinaryOps getOpcode() const
Definition: InstrTypes.h:442
static BinaryOperator * CreateNot(Value *Op, const Twine &Name="", InsertPosition InsertBefore=nullptr)
static BinaryOperator * Create(BinaryOps Op, Value *S1, Value *S2, const Twine &Name=Twine(), InsertPosition InsertBefore=nullptr)
Construct a binary instruction, given the opcode and the two operands.
static CastInst * CreateTruncOrBitCast(Value *S, Type *Ty, const Twine &Name="", InsertPosition InsertBefore=nullptr)
Create a Trunc or BitCast cast instruction.
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", InsertPosition InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass's ...
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:757
@ ICMP_SLE
signed less or equal
Definition: InstrTypes.h:787
@ ICMP_ULT
unsigned less than
Definition: InstrTypes.h:782
@ ICMP_EQ
equal
Definition: InstrTypes.h:778
@ ICMP_SGE
signed greater or equal
Definition: InstrTypes.h:785
static Constant * getSub(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2568
static Constant * getNot(Constant *C)
Definition: Constants.cpp:2555
static Constant * getAdd(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2561
static Constant * getTrunc(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:2203
static ConstantInt * getSigned(IntegerType *Ty, int64_t V)
Return a ConstantInt with the specified value for the specified type.
Definition: Constants.h:124
This is an important base class in LLVM.
Definition: Constant.h:41
static Constant * replaceUndefsWith(Constant *C, Constant *Replacement)
Try to replace undefined constant C or undefined elements in C with Replacement.
Definition: Constants.cpp:768
static Constant * mergeUndefsWith(Constant *C, Constant *Other)
Merges undefs of a Constant with another Constant, along with the undefs already present.
Definition: Constants.cpp:792
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:417
static Constant * getNullValue(Type *Ty)
Constructor to create a '0' constant of arbitrary type.
Definition: Constants.cpp:370
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:110
CallInst * CreateUnaryIntrinsic(Intrinsic::ID ID, Value *V, Instruction *FMFSource=nullptr, const Twine &Name="")
Create a call to intrinsic ID with 1 operand which is mangled on its type.
Definition: IRBuilder.cpp:913
Value * CreateICmpULT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2255
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1435
Value * CreateIsNotNeg(Value *Arg, const Twine &Name="")
Return a boolean value testing if Arg > -1.
Definition: IRBuilder.h:2557
Value * CreateNeg(Value *V, const Twine &Name="", bool HasNSW=false)
Definition: IRBuilder.h:1719
Value * CreateICmpEQ(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2239
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:143
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1414
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="", bool IsNonNeg=false)
Definition: IRBuilder.h:2019
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1473
Value * CreateAdd(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1325
Value * CreateIsNotNull(Value *Arg, const Twine &Name="")
Return a boolean value testing if Arg != 0.
Definition: IRBuilder.h:2547
Value * CreateTrunc(Value *V, Type *DestTy, const Twine &Name="", bool IsNUW=false, bool IsNSW=false)
Definition: IRBuilder.h:2005
Value * CreateBinOp(Instruction::BinaryOps Opc, Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1664
Value * CreateICmpSLT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2271
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block.
Definition: IRBuilder.h:178
Value * CreateAShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:1454
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2349
Instruction * FoldOpIntoSelect(Instruction &Op, SelectInst *SI, bool FoldWithMultiUse=false)
Given an instruction with a select as one operand and a constant as the other operand,...
Instruction * visitLShr(BinaryOperator &I)
Instruction * foldBinOpIntoSelectOrPhi(BinaryOperator &I)
This is a convenience wrapper function for the above two functions.
Value * reassociateShiftAmtsOfTwoSameDirectionShifts(BinaryOperator *Sh0, const SimplifyQuery &SQ, bool AnalyzeForSignBitExtraction=false)
Instruction * visitAShr(BinaryOperator &I)
Instruction * eraseInstFromFunction(Instruction &I) override
Combiner aware instruction erasure.
Instruction * visitShl(BinaryOperator &I)
Instruction * foldBinopWithPhiOperands(BinaryOperator &BO)
For a binary operator with 2 phi operands, try to hoist the binary operation before the phi.
Instruction * foldVariableSignZeroExtensionOfVariableHighBitExtract(BinaryOperator &OldAShr)
Instruction * commonShiftTransforms(BinaryOperator &I)
bool SimplifyDemandedInstructionBits(Instruction &Inst)
Tries to simplify operands to an integer instruction based on its demanded bits.
Instruction * foldVectorBinop(BinaryOperator &Inst)
Canonicalize the position of binops relative to shufflevector.
Instruction * FoldShiftByConstant(Value *Op0, Constant *Op1, BinaryOperator &I)
SimplifyQuery SQ
Definition: InstCombiner.h:76
Instruction * replaceInstUsesWith(Instruction &I, Value *V)
A combiner-aware RAUW-like routine.
Definition: InstCombiner.h:386
Instruction * InsertNewInstWith(Instruction *New, BasicBlock::iterator Old)
Same as InsertNewInstBefore, but also sets the debug loc.
Definition: InstCombiner.h:375
const DataLayout & DL
Definition: InstCombiner.h:75
AssumptionCache & AC
Definition: InstCombiner.h:72
void addToWorklist(Instruction *I)
Definition: InstCombiner.h:336
Instruction * replaceOperand(Instruction &I, unsigned OpNum, Value *V)
Replace operand of instruction and add old operand to the worklist.
Definition: InstCombiner.h:410
void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth, const Instruction *CxtI) const
Definition: InstCombiner.h:431
BuilderTy & Builder
Definition: InstCombiner.h:60
bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth=0, const Instruction *CxtI=nullptr) const
Definition: InstCombiner.h:447
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nuw flag on this instruction, which must be an operator which supports this flag.
bool hasNoUnsignedWrap() const LLVM_READONLY
Determine whether the no unsigned wrap flag is set.
bool hasNoSignedWrap() const LLVM_READONLY
Determine whether the no signed wrap flag is set.
void copyIRFlags(const Value *V, bool IncludeWrapFlags=true)
Convenience method to copy supported exact, fast-math, and (optionally) wrapping flags from V to this...
void setHasNoSignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag.
bool isCommutative() const LLVM_READONLY
Return true if the instruction is commutative:
bool isExact() const LLVM_READONLY
Determine whether the exact flag is set.
bool isLogicalShift() const
Return true if this is a logical shift left or a logical shift right.
Definition: Instruction.h:307
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:268
void setIsExact(bool b=true)
Set or clear the exact flag on this instruction, which must be an operator which supports this flag.
op_range incoming_values()
void setIncomingValue(unsigned i, Value *V)
Value * getIncomingValue(unsigned i) const
Return incoming value number x.
unsigned getNumIncomingValues() const
Return the number of incoming edges.
This class represents a sign extension of integer types.
This class represents the LLVM 'select' instruction.
static SelectInst * Create(Value *C, Value *S1, Value *S2, const Twine &NameStr="", InsertPosition InsertBefore=nullptr, Instruction *MDFrom=nullptr)
This class represents a truncation of integer types.
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:265
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:234
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type.
Type * getExtendedType() const
Given scalar/vector integer type, returns a type with elements twice as wide as in the original type.
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:228
void setOperand(unsigned i, Value *Val)
Definition: User.h:174
Value * getOperand(unsigned i) const
Definition: User.h:169
LLVM Value Representation.
Definition: Value.h:74
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:255
bool hasOneUse() const
Return true if there is exactly one use of this value.
Definition: Value.h:434
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:309
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:383
This class represents zero extension of integer types.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
@ C
The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
cst_pred_ty< is_all_ones > m_AllOnes()
Match an integer or vector with all bits set.
Definition: PatternMatch.h:524
BinaryOp_match< LHS, RHS, Instruction::And > m_And(const LHS &L, const RHS &R)
BinaryOp_match< LHS, RHS, Instruction::Add > m_Add(const LHS &L, const RHS &R)
class_match< BinaryOperator > m_BinOp()
Match an arbitrary binary operation and ignore it.
Definition: PatternMatch.h:100
BinaryOp_match< LHS, RHS, Instruction::AShr > m_AShr(const LHS &L, const RHS &R)
cst_pred_ty< is_power2 > m_Power2()
Match an integer or vector power-of-2.
Definition: PatternMatch.h:619
match_combine_or< CastInst_match< OpTy, TruncInst >, OpTy > m_TruncOrSelf(const OpTy &Op)
class_match< Constant > m_Constant()
Match an arbitrary Constant and ignore it.
Definition: PatternMatch.h:165
BinaryOp_match< LHS, RHS, Instruction::And, true > m_c_And(const LHS &L, const RHS &R)
Matches an And with LHS and RHS in either order.
CastInst_match< OpTy, TruncInst > m_Trunc(const OpTy &Op)
Matches Trunc.
BinaryOp_match< LHS, RHS, Instruction::Xor > m_Xor(const LHS &L, const RHS &R)
OverflowingBinaryOp_match< LHS, RHS, Instruction::Sub, OverflowingBinaryOperator::NoSignedWrap > m_NSWSub(const LHS &L, const RHS &R)
specific_intval< false > m_SpecificInt(const APInt &V)
Match a specific integer value or vector with all elements equal to the value.
Definition: PatternMatch.h:972
match_combine_or< CastInst_match< OpTy, ZExtInst >, OpTy > m_ZExtOrSelf(const OpTy &Op)
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
bind_ty< Instruction > m_Instruction(Instruction *&I)
Match an instruction, capturing it if we match.
Definition: PatternMatch.h:816
specificval_ty m_Specific(const Value *V)
Match if we have a specific specified value.
Definition: PatternMatch.h:875
BinOpPred_match< LHS, RHS, is_right_shift_op > m_Shr(const LHS &L, const RHS &R)
Matches logical shift operations.
specific_intval< true > m_SpecificIntAllowPoison(const APInt &V)
Definition: PatternMatch.h:980
cst_pred_ty< is_one > m_One()
Match an integer 1 or a vector with all elements equal to 1.
Definition: PatternMatch.h:592
ThreeOps_match< Cond, LHS, RHS, Instruction::Select > m_Select(const Cond &C, const LHS &L, const RHS &R)
Matches SelectInst.
match_combine_and< LTy, RTy > m_CombineAnd(const LTy &L, const RTy &R)
Combine two pattern matchers matching L && R.
Definition: PatternMatch.h:245
BinaryOp_match< LHS, RHS, Instruction::Mul > m_Mul(const LHS &L, const RHS &R)
deferredval_ty< Value > m_Deferred(Value *const &V)
Like m_Specific(), but works if the specific value to match is determined as part of the same match()...
Definition: PatternMatch.h:893
OneUse_match< T > m_OneUse(const T &SubPattern)
Definition: PatternMatch.h:67
BinaryOp_match< cst_pred_ty< is_zero_int >, ValTy, Instruction::Sub > m_Neg(const ValTy &V)
Matches a 'Neg' as 'sub 0, V'.
match_combine_and< class_match< Constant >, match_unless< constantexpr_match > > m_ImmConstant()
Match an arbitrary immediate Constant and ignore it.
Definition: PatternMatch.h:854
OverflowingBinaryOp_match< LHS, RHS, Instruction::Shl, OverflowingBinaryOperator::NoSignedWrap > m_NSWShl(const LHS &L, const RHS &R)
CastInst_match< OpTy, ZExtInst > m_ZExt(const OpTy &Op)
Matches ZExt.
OverflowingBinaryOp_match< LHS, RHS, Instruction::Shl, OverflowingBinaryOperator::NoUnsignedWrap > m_NUWShl(const LHS &L, const RHS &R)
OverflowingBinaryOp_match< LHS, RHS, Instruction::Mul, OverflowingBinaryOperator::NoUnsignedWrap > m_NUWMul(const LHS &L, const RHS &R)
BinaryOp_match< LHS, RHS, Instruction::Add, true > m_c_Add(const LHS &L, const RHS &R)
Matches a Add with LHS and RHS in either order.
BinaryOp_match< LHS, RHS, Instruction::SDiv > m_SDiv(const LHS &L, const RHS &R)
OverflowingBinaryOp_match< LHS, RHS, Instruction::Sub, OverflowingBinaryOperator::NoUnsignedWrap > m_NUWSub(const LHS &L, const RHS &R)
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt.
Definition: PatternMatch.h:299
class_match< Value > m_Value()
Match an arbitrary value and ignore it.
Definition: PatternMatch.h:92
AnyBinaryOp_match< LHS, RHS, true > m_c_BinOp(const LHS &L, const RHS &R)
Matches a BinaryOperator with LHS and RHS in either order.
BinaryOp_match< LHS, RHS, Instruction::LShr > m_LShr(const LHS &L, const RHS &R)
Exact_match< T > m_Exact(const T &SubPattern)
BinOpPred_match< LHS, RHS, is_shift_op > m_Shift(const LHS &L, const RHS &R)
Matches shift operations.
BinaryOp_match< LHS, RHS, Instruction::Shl > m_Shl(const LHS &L, const RHS &R)
BinaryOp_match< LHS, RHS, Instruction::SRem > m_SRem(const LHS &L, const RHS &R)
BinaryOp_match< cst_pred_ty< is_all_ones >, ValTy, Instruction::Xor, true > m_Not(const ValTy &V)
Matches a 'Not' as 'xor V, -1' or 'xor -1, V'.
BinaryOp_match< LHS, RHS, Instruction::Or > m_Or(const LHS &L, const RHS &R)
CastInst_match< OpTy, SExtInst > m_SExt(const OpTy &Op)
Matches SExt.
BinaryOp_match< LHS, RHS, Instruction::Or, true > m_c_Or(const LHS &L, const RHS &R)
Matches an Or with LHS and RHS in either order.
match_combine_or< OverflowingBinaryOp_match< LHS, RHS, Instruction::Add, OverflowingBinaryOperator::NoUnsignedWrap >, DisjointOr_match< LHS, RHS > > m_NUWAddLike(const LHS &L, const RHS &R)
Match either "add nuw" or "or disjoint".
OverflowingBinaryOp_match< LHS, RHS, Instruction::Mul, OverflowingBinaryOperator::NoSignedWrap > m_NSWMul(const LHS &L, const RHS &R)
BinaryOp_match< LHS, RHS, Instruction::Sub > m_Sub(const LHS &L, const RHS &R)
match_combine_or< LTy, RTy > m_CombineOr(const LTy &L, const RTy &R)
Combine two pattern matchers matching L || R.
Definition: PatternMatch.h:239
cst_pred_ty< icmp_pred_with_threshold > m_SpecificInt_ICMP(ICmpInst::Predicate Predicate, const APInt &Threshold)
Match an integer or vector with every element comparing 'pred' (eg/ne/...) to Threshold.
Definition: PatternMatch.h:698
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
Value * simplifyAShrInst(Value *Op0, Value *Op1, bool IsExact, const SimplifyQuery &Q)
Given operands for a AShr, fold the result or return nulll.
Value * simplifySubInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW, const SimplifyQuery &Q)
Given operands for a Sub, fold the result or return null.
Value * simplifyAddInst(Value *LHS, Value *RHS, bool IsNSW, bool IsNUW, const SimplifyQuery &Q)
Given operands for an Add, fold the result or return null.
unsigned Log2_32(uint32_t Value)
Return the floor log base 2 of the specified value, -1 if the value is zero.
Definition: MathExtras.h:324
Value * simplifyShlInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW, const SimplifyQuery &Q)
Given operands for a Shl, fold the result or return null.
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:275
Value * simplifyLShrInst(Value *Op0, Value *Op1, bool IsExact, const SimplifyQuery &Q)
Given operands for a LShr, fold the result or return null.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:163
Constant * ConstantFoldCastOperand(unsigned Opcode, Constant *C, Type *DestTy, const DataLayout &DL)
Attempt to constant fold a cast with the specified operand.
Constant * ConstantFoldBinaryOpOperands(unsigned Opcode, Constant *LHS, Constant *RHS, const DataLayout &DL)
Attempt to constant fold a binary operation with the specified operands.
@ And
Bitwise or logical AND of integers.
@ Add
Sum of integers.
void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
constexpr unsigned BitWidth
Definition: BitmaskEnum.h:191
unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return the number of times the sign bit of the register is replicated into the other bits.
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:860
unsigned countMinSignBits() const
Returns the number of times the sign bit is replicated into the other bits.
Definition: KnownBits.h:244
unsigned countMinTrailingZeros() const
Returns the minimum number of trailing zero bits.
Definition: KnownBits.h:231
unsigned getBitWidth() const
Get the bit width of this value.
Definition: KnownBits.h:40
unsigned countMinLeadingZeros() const
Returns the minimum number of leading zero bits.
Definition: KnownBits.h:237
APInt getMaxValue() const
Return the maximal unsigned value possible given these KnownBits.
Definition: KnownBits.h:134
const DataLayout & DL
Definition: SimplifyQuery.h:61
const Instruction * CxtI
Definition: SimplifyQuery.h:65
const DominatorTree * DT
Definition: SimplifyQuery.h:63
SimplifyQuery getWithInstruction(const Instruction *I) const
Definition: SimplifyQuery.h:96
AssumptionCache * AC
Definition: SimplifyQuery.h:64