1//===- InstCombineSimplifyDemanded.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 contains logic for simplifying instructions based on information
10// about how they are used.
11//
12//===----------------------------------------------------------------------===//
13
14#include "InstCombineInternal.h"
15#include "llvm/Analysis/ValueTracking.h"
16#include "llvm/IR/GetElementPtrTypeIterator.h"
17#include "llvm/IR/IntrinsicInst.h"
18#include "llvm/IR/PatternMatch.h"
19#include "llvm/IR/ProfDataUtils.h"
20#include "llvm/Support/KnownBits.h"
21#include "llvm/Transforms/InstCombine/InstCombiner.h"
22
23using namespace llvm;
24using namespace llvm::PatternMatch;
25
26#define DEBUG_TYPE "instcombine"
27
28static cl::opt<bool>
29 VerifyKnownBits("instcombine-verify-known-bits",
30 cl::desc("Verify that computeKnownBits() and "
31 "SimplifyDemandedBits() are consistent"),
32 cl::Hidden, cl::init(Val: false));
33
34static cl::opt<unsigned> SimplifyDemandedVectorEltsDepthLimit(
35 "instcombine-simplify-vector-elts-depth",
36 cl::desc(
37 "Depth limit when simplifying vector instructions and their operands"),
38 cl::Hidden, cl::init(Val: 10));
39
40/// Check to see if the specified operand of the specified instruction is a
41/// constant integer. If so, check to see if there are any bits set in the
42/// constant that are not demanded. If so, shrink the constant and return true.
43static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
44 const APInt &Demanded) {
45 assert(I && "No instruction?");
46 assert(OpNo < I->getNumOperands() && "Operand index too large");
47
48 // The operand must be a constant integer or splat integer.
49 Value *Op = I->getOperand(i: OpNo);
50 const APInt *C;
51 if (!match(V: Op, P: m_APInt(Res&: C)))
52 return false;
53
54 // If there are no bits set that aren't demanded, nothing to do.
55 if (C->isSubsetOf(RHS: Demanded))
56 return false;
57
58 // This instruction is producing bits that are not demanded. Shrink the RHS.
59 I->setOperand(i: OpNo, Val: ConstantInt::get(Ty: Op->getType(), V: *C & Demanded));
60
61 return true;
62}
63
64/// Let N = 2 * M.
65/// Given an N-bit integer representing a pack of two M-bit integers,
66/// we can select one of the packed integers by right-shifting by either
67/// zero or M (which is the most straightforward to check if M is a power
68/// of 2), and then isolating the lower M bits. In this case, we can
69/// represent the shift as a select on whether the shr amount is nonzero.
70static Value *simplifyShiftSelectingPackedElement(Instruction *I,
71 const APInt &DemandedMask,
72 InstCombinerImpl &IC,
73 unsigned Depth) {
74 assert(I->getOpcode() == Instruction::LShr &&
75 "Only lshr instruction supported");
76
77 uint64_t ShlAmt;
78 Value *Upper, *Lower;
79 if (!match(V: I->getOperand(i: 0),
80 P: m_OneUse(SubPattern: m_c_DisjointOr(
81 L: m_OneUse(SubPattern: m_Shl(L: m_Value(V&: Upper), R: m_ConstantInt(V&: ShlAmt))),
82 R: m_Value(V&: Lower)))))
83 return nullptr;
84
85 if (!isPowerOf2_64(Value: ShlAmt))
86 return nullptr;
87
88 const uint64_t DemandedBitWidth = DemandedMask.getActiveBits();
89 if (DemandedBitWidth > ShlAmt)
90 return nullptr;
91
92 // Check that upper demanded bits are not lost from lshift.
93 if (Upper->getType()->getScalarSizeInBits() < ShlAmt + DemandedBitWidth)
94 return nullptr;
95
96 KnownBits KnownLowerBits = IC.computeKnownBits(V: Lower, CxtI: I, Depth);
97 if (!KnownLowerBits.getMaxValue().isIntN(N: ShlAmt))
98 return nullptr;
99
100 Value *ShrAmt = I->getOperand(i: 1);
101 KnownBits KnownShrBits = IC.computeKnownBits(V: ShrAmt, CxtI: I, Depth);
102
103 // Verify that ShrAmt is either exactly ShlAmt (which is a power of 2) or
104 // zero.
105 if (~KnownShrBits.Zero != ShlAmt)
106 return nullptr;
107
108 IRBuilderBase::InsertPointGuard Guard(IC.Builder);
109 IC.Builder.SetInsertPoint(I);
110 Value *ShrAmtZ =
111 IC.Builder.CreateICmpEQ(LHS: ShrAmt, RHS: Constant::getNullValue(Ty: ShrAmt->getType()),
112 Name: ShrAmt->getName() + ".z");
113 // There is no existing !prof metadata we can derive the !prof metadata for
114 // this select.
115 Value *Select = IC.Builder.CreateSelectWithUnknownProfile(C: ShrAmtZ, True: Lower,
116 False: Upper, DEBUG_TYPE);
117 Select->takeName(V: I);
118 return Select;
119}
120
121/// Returns the bitwidth of the given scalar or pointer type. For vector types,
122/// returns the element type's bitwidth.
123static unsigned getBitWidth(Type *Ty, const DataLayout &DL) {
124 if (unsigned BitWidth = Ty->getScalarSizeInBits())
125 return BitWidth;
126
127 return DL.getPointerTypeSizeInBits(Ty);
128}
129
130/// Inst is an integer instruction that SimplifyDemandedBits knows about. See if
131/// the instruction has any properties that allow us to simplify its operands.
132bool InstCombinerImpl::SimplifyDemandedInstructionBits(Instruction &Inst,
133 KnownBits &Known) {
134 APInt DemandedMask(APInt::getAllOnes(numBits: Known.getBitWidth()));
135 Value *V = SimplifyDemandedUseBits(I: &Inst, DemandedMask, Known,
136 Q: SQ.getWithInstruction(I: &Inst));
137 if (!V) return false;
138 if (V == &Inst) return true;
139 replaceInstUsesWith(I&: Inst, V);
140 return true;
141}
142
143/// Inst is an integer instruction that SimplifyDemandedBits knows about. See if
144/// the instruction has any properties that allow us to simplify its operands.
145bool InstCombinerImpl::SimplifyDemandedInstructionBits(Instruction &Inst) {
146 KnownBits Known(getBitWidth(Ty: Inst.getType(), DL));
147 return SimplifyDemandedInstructionBits(Inst, Known);
148}
149
150bool InstCombinerImpl::SimplifyDemandedInstructionFPClass(Instruction &Inst) {
151 KnownFPClass Known;
152
153 Value *V =
154 SimplifyDemandedUseFPClass(I: &Inst, DemandedMask: fcAllFlags, Known, /*CtxI=*/CxtI: &Inst);
155 if (!V)
156 return false;
157 if (V == &Inst)
158 return true;
159 replaceInstUsesWith(I&: Inst, V);
160 return true;
161}
162
163/// This form of SimplifyDemandedBits simplifies the specified instruction
164/// operand if possible, updating it in place. It returns true if it made any
165/// change and false otherwise.
166bool InstCombinerImpl::SimplifyDemandedBits(Instruction *I, unsigned OpNo,
167 const APInt &DemandedMask,
168 KnownBits &Known,
169 const SimplifyQuery &Q,
170 unsigned Depth) {
171 Use &U = I->getOperandUse(i: OpNo);
172 Value *V = U.get();
173 if (isa<Constant>(Val: V)) {
174 llvm::computeKnownBits(V, Known, Q, Depth);
175 return false;
176 }
177
178 Known.resetAll();
179 if (DemandedMask.isZero()) {
180 // Not demanding any bits from V.
181 replaceUse(U, NewValue: UndefValue::get(T: V->getType()));
182 return true;
183 }
184
185 Instruction *VInst = dyn_cast<Instruction>(Val: V);
186 if (!VInst) {
187 llvm::computeKnownBits(V, Known, Q, Depth);
188 return false;
189 }
190
191 if (Depth == MaxAnalysisRecursionDepth)
192 return false;
193
194 Value *NewVal;
195 if (VInst->hasOneUse()) {
196 // If the instruction has one use, we can directly simplify it.
197 NewVal = SimplifyDemandedUseBits(I: VInst, DemandedMask, Known, Q, Depth);
198 } else {
199 // If there are multiple uses of this instruction, then we can simplify
200 // VInst to some other value, but not modify the instruction.
201 NewVal =
202 SimplifyMultipleUseDemandedBits(I: VInst, DemandedMask, Known, Q, Depth);
203 }
204 if (!NewVal) return false;
205 if (Instruction* OpInst = dyn_cast<Instruction>(Val&: U))
206 salvageDebugInfo(I&: *OpInst);
207
208 replaceUse(U, NewValue: NewVal);
209 return true;
210}
211
212/// This function attempts to replace V with a simpler value based on the
213/// demanded bits. When this function is called, it is known that only the bits
214/// set in DemandedMask of the result of V are ever used downstream.
215/// Consequently, depending on the mask and V, it may be possible to replace V
216/// with a constant or one of its operands. In such cases, this function does
217/// the replacement and returns true. In all other cases, it returns false after
218/// analyzing the expression and setting KnownOne and known to be one in the
219/// expression. Known.Zero contains all the bits that are known to be zero in
220/// the expression. These are provided to potentially allow the caller (which
221/// might recursively be SimplifyDemandedBits itself) to simplify the
222/// expression.
223/// Known.One and Known.Zero always follow the invariant that:
224/// Known.One & Known.Zero == 0.
225/// That is, a bit can't be both 1 and 0. The bits in Known.One and Known.Zero
226/// are accurate even for bits not in DemandedMask. Note
227/// also that the bitwidth of V, DemandedMask, Known.Zero and Known.One must all
228/// be the same.
229///
230/// This returns null if it did not change anything and it permits no
231/// simplification. This returns V itself if it did some simplification of V's
232/// operands based on the information about what bits are demanded. This returns
233/// some other non-null value if it found out that V is equal to another value
234/// in the context where the specified bits are demanded, but not for all users.
235Value *InstCombinerImpl::SimplifyDemandedUseBits(Instruction *I,
236 const APInt &DemandedMask,
237 KnownBits &Known,
238 const SimplifyQuery &Q,
239 unsigned Depth) {
240 assert(I != nullptr && "Null pointer of Value???");
241 assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
242 uint32_t BitWidth = DemandedMask.getBitWidth();
243 Type *VTy = I->getType();
244 assert(
245 (!VTy->isIntOrIntVectorTy() || VTy->getScalarSizeInBits() == BitWidth) &&
246 Known.getBitWidth() == BitWidth &&
247 "Value *V, DemandedMask and Known must have same BitWidth");
248
249 KnownBits LHSKnown(BitWidth), RHSKnown(BitWidth);
250
251 // Update flags after simplifying an operand based on the fact that some high
252 // order bits are not demanded.
253 auto disableWrapFlagsBasedOnUnusedHighBits = [](Instruction *I,
254 unsigned NLZ) {
255 if (NLZ > 0) {
256 // Disable the nsw and nuw flags here: We can no longer guarantee that
257 // we won't wrap after simplification. Removing the nsw/nuw flags is
258 // legal here because the top bit is not demanded.
259 I->setHasNoSignedWrap(false);
260 I->setHasNoUnsignedWrap(false);
261 }
262 return I;
263 };
264
265 // If the high-bits of an ADD/SUB/MUL are not demanded, then we do not care
266 // about the high bits of the operands.
267 auto simplifyOperandsBasedOnUnusedHighBits = [&](APInt &DemandedFromOps) {
268 unsigned NLZ = DemandedMask.countl_zero();
269 // Right fill the mask of bits for the operands to demand the most
270 // significant bit and all those below it.
271 DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
272 if (ShrinkDemandedConstant(I, OpNo: 0, Demanded: DemandedFromOps) ||
273 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromOps, Known&: LHSKnown, Q, Depth: Depth + 1) ||
274 ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromOps) ||
275 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedFromOps, Known&: RHSKnown, Q, Depth: Depth + 1)) {
276 disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
277 return true;
278 }
279 return false;
280 };
281
282 switch (I->getOpcode()) {
283 default:
284 llvm::computeKnownBits(V: I, Known, Q, Depth);
285 break;
286 case Instruction::And: {
287 // If either the LHS or the RHS are Zero, the result is zero.
288 if (SimplifyDemandedBits(I, OpNo: 1, DemandedMask, Known&: RHSKnown, Q, Depth: Depth + 1) ||
289 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMask & ~RHSKnown.Zero, Known&: LHSKnown, Q,
290 Depth: Depth + 1))
291 return I;
292
293 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
294 SQ: Q, Depth);
295
296 // If the client is only demanding bits that we know, return the known
297 // constant.
298 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
299 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
300
301 // If all of the demanded bits are known 1 on one side, return the other.
302 // These bits cannot contribute to the result of the 'and'.
303 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero | RHSKnown.One))
304 return I->getOperand(i: 0);
305 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero | LHSKnown.One))
306 return I->getOperand(i: 1);
307
308 // If the RHS is a constant, see if we can simplify it.
309 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedMask & ~LHSKnown.Zero))
310 return I;
311
312 break;
313 }
314 case Instruction::Or: {
315 // If either the LHS or the RHS are One, the result is One.
316 if (SimplifyDemandedBits(I, OpNo: 1, DemandedMask, Known&: RHSKnown, Q, Depth: Depth + 1) ||
317 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMask & ~RHSKnown.One, Known&: LHSKnown, Q,
318 Depth: Depth + 1)) {
319 // Disjoint flag may not longer hold.
320 I->dropPoisonGeneratingFlags();
321 return I;
322 }
323
324 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
325 SQ: Q, Depth);
326
327 // If the client is only demanding bits that we know, return the known
328 // constant.
329 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
330 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
331
332 // If all of the demanded bits are known zero on one side, return the other.
333 // These bits cannot contribute to the result of the 'or'.
334 if (DemandedMask.isSubsetOf(RHS: LHSKnown.One | RHSKnown.Zero))
335 return I->getOperand(i: 0);
336 if (DemandedMask.isSubsetOf(RHS: RHSKnown.One | LHSKnown.Zero))
337 return I->getOperand(i: 1);
338
339 // If the RHS is a constant, see if we can simplify it.
340 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedMask))
341 return I;
342
343 // Infer disjoint flag if no common bits are set.
344 if (!cast<PossiblyDisjointInst>(Val: I)->isDisjoint()) {
345 WithCache<const Value *> LHSCache(I->getOperand(i: 0), LHSKnown),
346 RHSCache(I->getOperand(i: 1), RHSKnown);
347 if (haveNoCommonBitsSet(LHSCache, RHSCache, SQ: Q)) {
348 cast<PossiblyDisjointInst>(Val: I)->setIsDisjoint(true);
349 return I;
350 }
351 }
352
353 break;
354 }
355 case Instruction::Xor: {
356 if (SimplifyDemandedBits(I, OpNo: 1, DemandedMask, Known&: RHSKnown, Q, Depth: Depth + 1) ||
357 SimplifyDemandedBits(I, OpNo: 0, DemandedMask, Known&: LHSKnown, Q, Depth: Depth + 1))
358 return I;
359 Value *LHS, *RHS;
360 if (DemandedMask == 1 &&
361 match(V: I->getOperand(i: 0), P: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: LHS))) &&
362 match(V: I->getOperand(i: 1), P: m_Intrinsic<Intrinsic::ctpop>(Op0: m_Value(V&: RHS)))) {
363 // (ctpop(X) ^ ctpop(Y)) & 1 --> ctpop(X^Y) & 1
364 IRBuilderBase::InsertPointGuard Guard(Builder);
365 Builder.SetInsertPoint(I);
366 auto *Xor = Builder.CreateXor(LHS, RHS);
367 return Builder.CreateUnaryIntrinsic(ID: Intrinsic::ctpop, V: Xor);
368 }
369
370 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
371 SQ: Q, Depth);
372
373 // If the client is only demanding bits that we know, return the known
374 // constant.
375 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
376 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
377
378 // If all of the demanded bits are known zero on one side, return the other.
379 // These bits cannot contribute to the result of the 'xor'.
380 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero))
381 return I->getOperand(i: 0);
382 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero))
383 return I->getOperand(i: 1);
384
385 // If all of the demanded bits are known to be zero on one side or the
386 // other, turn this into an *inclusive* or.
387 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
388 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero | LHSKnown.Zero)) {
389 Instruction *Or =
390 BinaryOperator::CreateOr(V1: I->getOperand(i: 0), V2: I->getOperand(i: 1));
391 if (DemandedMask.isAllOnes())
392 cast<PossiblyDisjointInst>(Val: Or)->setIsDisjoint(true);
393 Or->takeName(V: I);
394 return InsertNewInstWith(New: Or, Old: I->getIterator());
395 }
396
397 // If all of the demanded bits on one side are known, and all of the set
398 // bits on that side are also known to be set on the other side, turn this
399 // into an AND, as we know the bits will be cleared.
400 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
401 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero|RHSKnown.One) &&
402 RHSKnown.One.isSubsetOf(RHS: LHSKnown.One)) {
403 Constant *AndC = Constant::getIntegerValue(Ty: VTy,
404 V: ~RHSKnown.One & DemandedMask);
405 Instruction *And = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: AndC);
406 return InsertNewInstWith(New: And, Old: I->getIterator());
407 }
408
409 // If the RHS is a constant, see if we can change it. Don't alter a -1
410 // constant because that's a canonical 'not' op, and that is better for
411 // combining, SCEV, and codegen.
412 const APInt *C;
413 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) && !C->isAllOnes()) {
414 if ((*C | ~DemandedMask).isAllOnes()) {
415 // Force bits to 1 to create a 'not' op.
416 I->setOperand(i: 1, Val: ConstantInt::getAllOnesValue(Ty: VTy));
417 return I;
418 }
419 // If we can't turn this into a 'not', try to shrink the constant.
420 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedMask))
421 return I;
422 }
423
424 // If our LHS is an 'and' and if it has one use, and if any of the bits we
425 // are flipping are known to be set, then the xor is just resetting those
426 // bits to zero. We can just knock out bits from the 'and' and the 'xor',
427 // simplifying both of them.
428 if (Instruction *LHSInst = dyn_cast<Instruction>(Val: I->getOperand(i: 0))) {
429 ConstantInt *AndRHS, *XorRHS;
430 if (LHSInst->getOpcode() == Instruction::And && LHSInst->hasOneUse() &&
431 match(V: I->getOperand(i: 1), P: m_ConstantInt(CI&: XorRHS)) &&
432 match(V: LHSInst->getOperand(i: 1), P: m_ConstantInt(CI&: AndRHS)) &&
433 (LHSKnown.One & RHSKnown.One & DemandedMask) != 0) {
434 APInt NewMask = ~(LHSKnown.One & RHSKnown.One & DemandedMask);
435
436 Constant *AndC = ConstantInt::get(Ty: VTy, V: NewMask & AndRHS->getValue());
437 Instruction *NewAnd = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: AndC);
438 InsertNewInstWith(New: NewAnd, Old: I->getIterator());
439
440 Constant *XorC = ConstantInt::get(Ty: VTy, V: NewMask & XorRHS->getValue());
441 Instruction *NewXor = BinaryOperator::CreateXor(V1: NewAnd, V2: XorC);
442 return InsertNewInstWith(New: NewXor, Old: I->getIterator());
443 }
444 }
445 break;
446 }
447 case Instruction::Select: {
448 if (SimplifyDemandedBits(I, OpNo: 2, DemandedMask, Known&: RHSKnown, Q, Depth: Depth + 1) ||
449 SimplifyDemandedBits(I, OpNo: 1, DemandedMask, Known&: LHSKnown, Q, Depth: Depth + 1))
450 return I;
451
452 // If the operands are constants, see if we can simplify them.
453 // This is similar to ShrinkDemandedConstant, but for a select we want to
454 // try to keep the selected constants the same as icmp value constants, if
455 // we can. This helps not break apart (or helps put back together)
456 // canonical patterns like min and max.
457 auto CanonicalizeSelectConstant = [](Instruction *I, unsigned OpNo,
458 const APInt &DemandedMask) {
459 const APInt *SelC;
460 if (!match(V: I->getOperand(i: OpNo), P: m_APInt(Res&: SelC)))
461 return false;
462
463 // Get the constant out of the ICmp, if there is one.
464 // Only try this when exactly 1 operand is a constant (if both operands
465 // are constant, the icmp should eventually simplify). Otherwise, we may
466 // invert the transform that reduces set bits and infinite-loop.
467 Value *X;
468 const APInt *CmpC;
469 if (!match(V: I->getOperand(i: 0), P: m_ICmp(L: m_Value(V&: X), R: m_APInt(Res&: CmpC))) ||
470 isa<Constant>(Val: X) || CmpC->getBitWidth() != SelC->getBitWidth())
471 return ShrinkDemandedConstant(I, OpNo, Demanded: DemandedMask);
472
473 // If the constant is already the same as the ICmp, leave it as-is.
474 if (*CmpC == *SelC)
475 return false;
476 // If the constants are not already the same, but can be with the demand
477 // mask, use the constant value from the ICmp.
478 if ((*CmpC & DemandedMask) == (*SelC & DemandedMask)) {
479 I->setOperand(i: OpNo, Val: ConstantInt::get(Ty: I->getType(), V: *CmpC));
480 return true;
481 }
482 return ShrinkDemandedConstant(I, OpNo, Demanded: DemandedMask);
483 };
484 if (CanonicalizeSelectConstant(I, 1, DemandedMask) ||
485 CanonicalizeSelectConstant(I, 2, DemandedMask))
486 return I;
487
488 // Only known if known in both the LHS and RHS.
489 adjustKnownBitsForSelectArm(Known&: LHSKnown, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
490 /*Invert=*/false, Q, Depth);
491 adjustKnownBitsForSelectArm(Known&: RHSKnown, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
492 /*Invert=*/true, Q, Depth);
493 Known = LHSKnown.intersectWith(RHS: RHSKnown);
494 break;
495 }
496 case Instruction::Trunc: {
497 // If we do not demand the high bits of a right-shifted and truncated value,
498 // then we may be able to truncate it before the shift.
499 Value *X;
500 const APInt *C;
501 if (match(V: I->getOperand(i: 0), P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_APInt(Res&: C))))) {
502 // The shift amount must be valid (not poison) in the narrow type, and
503 // it must not be greater than the high bits demanded of the result.
504 if (C->ult(RHS: VTy->getScalarSizeInBits()) &&
505 C->ule(RHS: DemandedMask.countl_zero())) {
506 // trunc (lshr X, C) --> lshr (trunc X), C
507 IRBuilderBase::InsertPointGuard Guard(Builder);
508 Builder.SetInsertPoint(I);
509 Value *Trunc = Builder.CreateTrunc(V: X, DestTy: VTy);
510 return Builder.CreateLShr(LHS: Trunc, RHS: C->getZExtValue());
511 }
512 }
513 }
514 [[fallthrough]];
515 case Instruction::ZExt: {
516 unsigned SrcBitWidth = I->getOperand(i: 0)->getType()->getScalarSizeInBits();
517
518 APInt InputDemandedMask = DemandedMask.zextOrTrunc(width: SrcBitWidth);
519 KnownBits InputKnown(SrcBitWidth);
520 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: InputDemandedMask, Known&: InputKnown, Q,
521 Depth: Depth + 1)) {
522 // For zext nneg, we may have dropped the instruction which made the
523 // input non-negative.
524 I->dropPoisonGeneratingFlags();
525 return I;
526 }
527 assert(InputKnown.getBitWidth() == SrcBitWidth && "Src width changed?");
528 if (I->getOpcode() == Instruction::ZExt && I->hasNonNeg() &&
529 !InputKnown.isNegative())
530 InputKnown.makeNonNegative();
531 Known = InputKnown.zextOrTrunc(BitWidth);
532
533 break;
534 }
535 case Instruction::SExt: {
536 // Compute the bits in the result that are not present in the input.
537 unsigned SrcBitWidth = I->getOperand(i: 0)->getType()->getScalarSizeInBits();
538
539 APInt InputDemandedBits = DemandedMask.trunc(width: SrcBitWidth);
540
541 // If any of the sign extended bits are demanded, we know that the sign
542 // bit is demanded.
543 if (DemandedMask.getActiveBits() > SrcBitWidth)
544 InputDemandedBits.setBit(SrcBitWidth-1);
545
546 KnownBits InputKnown(SrcBitWidth);
547 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: InputDemandedBits, Known&: InputKnown, Q, Depth: Depth + 1))
548 return I;
549
550 // If the input sign bit is known zero, or if the NewBits are not demanded
551 // convert this into a zero extension.
552 if (InputKnown.isNonNegative() ||
553 DemandedMask.getActiveBits() <= SrcBitWidth) {
554 // Convert to ZExt cast.
555 CastInst *NewCast = new ZExtInst(I->getOperand(i: 0), VTy);
556 NewCast->takeName(V: I);
557 return InsertNewInstWith(New: NewCast, Old: I->getIterator());
558 }
559
560 // If the sign bit of the input is known set or clear, then we know the
561 // top bits of the result.
562 Known = InputKnown.sext(BitWidth);
563 break;
564 }
565 case Instruction::Add: {
566 if ((DemandedMask & 1) == 0) {
567 // If we do not need the low bit, try to convert bool math to logic:
568 // add iN (zext i1 X), (sext i1 Y) --> sext (~X & Y) to iN
569 Value *X, *Y;
570 if (match(V: I, P: m_c_Add(L: m_OneUse(SubPattern: m_ZExt(Op: m_Value(V&: X))),
571 R: m_OneUse(SubPattern: m_SExt(Op: m_Value(V&: Y))))) &&
572 X->getType()->isIntOrIntVectorTy(BitWidth: 1) && X->getType() == Y->getType()) {
573 // Truth table for inputs and output signbits:
574 // X:0 | X:1
575 // ----------
576 // Y:0 | 0 | 0 |
577 // Y:1 | -1 | 0 |
578 // ----------
579 IRBuilderBase::InsertPointGuard Guard(Builder);
580 Builder.SetInsertPoint(I);
581 Value *AndNot = Builder.CreateAnd(LHS: Builder.CreateNot(V: X), RHS: Y);
582 return Builder.CreateSExt(V: AndNot, DestTy: VTy);
583 }
584
585 // add iN (sext i1 X), (sext i1 Y) --> sext (X | Y) to iN
586 if (match(V: I, P: m_Add(L: m_SExt(Op: m_Value(V&: X)), R: m_SExt(Op: m_Value(V&: Y)))) &&
587 X->getType()->isIntOrIntVectorTy(BitWidth: 1) && X->getType() == Y->getType() &&
588 (I->getOperand(i: 0)->hasOneUse() || I->getOperand(i: 1)->hasOneUse())) {
589
590 // Truth table for inputs and output signbits:
591 // X:0 | X:1
592 // -----------
593 // Y:0 | -1 | -1 |
594 // Y:1 | -1 | 0 |
595 // -----------
596 IRBuilderBase::InsertPointGuard Guard(Builder);
597 Builder.SetInsertPoint(I);
598 Value *Or = Builder.CreateOr(LHS: X, RHS: Y);
599 return Builder.CreateSExt(V: Or, DestTy: VTy);
600 }
601 }
602
603 // Right fill the mask of bits for the operands to demand the most
604 // significant bit and all those below it.
605 unsigned NLZ = DemandedMask.countl_zero();
606 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
607 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromOps) ||
608 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedFromOps, Known&: RHSKnown, Q, Depth: Depth + 1))
609 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
610
611 // If low order bits are not demanded and known to be zero in one operand,
612 // then we don't need to demand them from the other operand, since they
613 // can't cause overflow into any bits that are demanded in the result.
614 unsigned NTZ = (~DemandedMask & RHSKnown.Zero).countr_one();
615 APInt DemandedFromLHS = DemandedFromOps;
616 DemandedFromLHS.clearLowBits(loBits: NTZ);
617 if (ShrinkDemandedConstant(I, OpNo: 0, Demanded: DemandedFromLHS) ||
618 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromLHS, Known&: LHSKnown, Q, Depth: Depth + 1))
619 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
620
621 unsigned NtzLHS = (~DemandedMask & LHSKnown.Zero).countr_one();
622 APInt DemandedFromRHS = DemandedFromOps;
623 DemandedFromRHS.clearLowBits(loBits: NtzLHS);
624 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromRHS))
625 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
626
627 // If we are known to be adding zeros to every bit below
628 // the highest demanded bit, we just return the other side.
629 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
630 return I->getOperand(i: 0);
631 if (DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
632 return I->getOperand(i: 1);
633
634 // (add X, C) --> (xor X, C) IFF C is equal to the top bit of the DemandMask
635 {
636 const APInt *C;
637 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) &&
638 C->isOneBitSet(BitNo: DemandedMask.getActiveBits() - 1)) {
639 IRBuilderBase::InsertPointGuard Guard(Builder);
640 Builder.SetInsertPoint(I);
641 return Builder.CreateXor(LHS: I->getOperand(i: 0), RHS: ConstantInt::get(Ty: VTy, V: *C));
642 }
643 }
644
645 // Otherwise just compute the known bits of the result.
646 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
647 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
648 Known = KnownBits::add(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
649 break;
650 }
651 case Instruction::Sub: {
652 // Right fill the mask of bits for the operands to demand the most
653 // significant bit and all those below it.
654 unsigned NLZ = DemandedMask.countl_zero();
655 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
656 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromOps) ||
657 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedFromOps, Known&: RHSKnown, Q, Depth: Depth + 1))
658 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
659
660 // If low order bits are not demanded and are known to be zero in RHS,
661 // then we don't need to demand them from LHS, since they can't cause a
662 // borrow from any bits that are demanded in the result.
663 unsigned NTZ = (~DemandedMask & RHSKnown.Zero).countr_one();
664 APInt DemandedFromLHS = DemandedFromOps;
665 DemandedFromLHS.clearLowBits(loBits: NTZ);
666 if (ShrinkDemandedConstant(I, OpNo: 0, Demanded: DemandedFromLHS) ||
667 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromLHS, Known&: LHSKnown, Q, Depth: Depth + 1))
668 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
669
670 // If we are known to be subtracting zeros from every bit below
671 // the highest demanded bit, we just return the other side.
672 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
673 return I->getOperand(i: 0);
674 // We can't do this with the LHS for subtraction, unless we are only
675 // demanding the LSB.
676 if (DemandedFromOps.isOne() && DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
677 return I->getOperand(i: 1);
678
679 // Canonicalize sub mask, X -> ~X
680 const APInt *LHSC;
681 if (match(V: I->getOperand(i: 0), P: m_LowBitMask(V&: LHSC)) &&
682 DemandedFromOps.isSubsetOf(RHS: *LHSC)) {
683 IRBuilderBase::InsertPointGuard Guard(Builder);
684 Builder.SetInsertPoint(I);
685 return Builder.CreateNot(V: I->getOperand(i: 1));
686 }
687
688 // Otherwise just compute the known bits of the result.
689 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
690 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
691 Known = KnownBits::sub(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
692 break;
693 }
694 case Instruction::Mul: {
695 APInt DemandedFromOps;
696 if (simplifyOperandsBasedOnUnusedHighBits(DemandedFromOps))
697 return I;
698
699 if (DemandedMask.isPowerOf2()) {
700 // The LSB of X*Y is set only if (X & 1) == 1 and (Y & 1) == 1.
701 // If we demand exactly one bit N and we have "X * (C' << N)" where C' is
702 // odd (has LSB set), then the left-shifted low bit of X is the answer.
703 unsigned CTZ = DemandedMask.countr_zero();
704 const APInt *C;
705 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) && C->countr_zero() == CTZ) {
706 Constant *ShiftC = ConstantInt::get(Ty: VTy, V: CTZ);
707 Instruction *Shl = BinaryOperator::CreateShl(V1: I->getOperand(i: 0), V2: ShiftC);
708 return InsertNewInstWith(New: Shl, Old: I->getIterator());
709 }
710 }
711 // For a squared value "X * X", the bottom 2 bits are 0 and X[0] because:
712 // X * X is odd iff X is odd.
713 // 'Quadratic Reciprocity': X * X -> 0 for bit[1]
714 if (I->getOperand(i: 0) == I->getOperand(i: 1) && DemandedMask.ult(RHS: 4)) {
715 Constant *One = ConstantInt::get(Ty: VTy, V: 1);
716 Instruction *And1 = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: One);
717 return InsertNewInstWith(New: And1, Old: I->getIterator());
718 }
719
720 llvm::computeKnownBits(V: I, Known, Q, Depth);
721 break;
722 }
723 case Instruction::Shl: {
724 const APInt *SA;
725 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
726 const APInt *ShrAmt;
727 if (match(V: I->getOperand(i: 0), P: m_Shr(L: m_Value(), R: m_APInt(Res&: ShrAmt))))
728 if (Instruction *Shr = dyn_cast<Instruction>(Val: I->getOperand(i: 0)))
729 if (Value *R = simplifyShrShlDemandedBits(Shr, ShrOp1: *ShrAmt, Shl: I, ShlOp1: *SA,
730 DemandedMask, Known))
731 return R;
732
733 // Do not simplify if shl is part of funnel-shift pattern
734 if (I->hasOneUse()) {
735 auto *Inst = dyn_cast<Instruction>(Val: I->user_back());
736 if (Inst && Inst->getOpcode() == BinaryOperator::Or) {
737 if (auto Opt = convertOrOfShiftsToFunnelShift(Or&: *Inst)) {
738 auto [IID, FShiftArgs] = *Opt;
739 if ((IID == Intrinsic::fshl || IID == Intrinsic::fshr) &&
740 FShiftArgs[0] == FShiftArgs[1]) {
741 llvm::computeKnownBits(V: I, Known, Q, Depth);
742 break;
743 }
744 }
745 }
746 }
747
748 // We only want bits that already match the signbit then we don't
749 // need to shift.
750 uint64_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth - 1);
751 if (DemandedMask.countr_zero() >= ShiftAmt) {
752 if (I->hasNoSignedWrap()) {
753 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
754 unsigned SignBits =
755 ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
756 if (SignBits > ShiftAmt && SignBits - ShiftAmt >= NumHiDemandedBits)
757 return I->getOperand(i: 0);
758 }
759
760 // If we can pre-shift a right-shifted constant to the left without
761 // losing any high bits and we don't demand the low bits, then eliminate
762 // the left-shift:
763 // (C >> X) << LeftShiftAmtC --> (C << LeftShiftAmtC) >> X
764 Value *X;
765 Constant *C;
766 if (match(V: I->getOperand(i: 0), P: m_LShr(L: m_ImmConstant(C), R: m_Value(V&: X)))) {
767 Constant *LeftShiftAmtC = ConstantInt::get(Ty: VTy, V: ShiftAmt);
768 Constant *NewC = ConstantFoldBinaryOpOperands(Opcode: Instruction::Shl, LHS: C,
769 RHS: LeftShiftAmtC, DL);
770 if (ConstantFoldBinaryOpOperands(Opcode: Instruction::LShr, LHS: NewC,
771 RHS: LeftShiftAmtC, DL) == C) {
772 Instruction *Lshr = BinaryOperator::CreateLShr(V1: NewC, V2: X);
773 return InsertNewInstWith(New: Lshr, Old: I->getIterator());
774 }
775 }
776 }
777
778 APInt DemandedMaskIn(DemandedMask.lshr(shiftAmt: ShiftAmt));
779
780 // If the shift is NUW/NSW, then it does demand the high bits.
781 ShlOperator *IOp = cast<ShlOperator>(Val: I);
782 if (IOp->hasNoSignedWrap())
783 DemandedMaskIn.setHighBits(ShiftAmt+1);
784 else if (IOp->hasNoUnsignedWrap())
785 DemandedMaskIn.setHighBits(ShiftAmt);
786
787 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1))
788 return I;
789
790 Known = KnownBits::shl(LHS: Known,
791 RHS: KnownBits::makeConstant(C: APInt(BitWidth, ShiftAmt)),
792 /* NUW */ IOp->hasNoUnsignedWrap(),
793 /* NSW */ IOp->hasNoSignedWrap());
794 } else {
795 // This is a variable shift, so we can't shift the demand mask by a known
796 // amount. But if we are not demanding high bits, then we are not
797 // demanding those bits from the pre-shifted operand either.
798 if (unsigned CTLZ = DemandedMask.countl_zero()) {
799 APInt DemandedFromOp(APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - CTLZ));
800 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromOp, Known, Q, Depth: Depth + 1)) {
801 // We can't guarantee that nsw/nuw hold after simplifying the operand.
802 I->dropPoisonGeneratingFlags();
803 return I;
804 }
805 }
806 llvm::computeKnownBits(V: I, Known, Q, Depth);
807 }
808 break;
809 }
810 case Instruction::LShr: {
811 const APInt *SA;
812 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
813 uint64_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth-1);
814
815 // Do not simplify if lshr is part of funnel-shift pattern
816 if (I->hasOneUse()) {
817 auto *Inst = dyn_cast<Instruction>(Val: I->user_back());
818 if (Inst && Inst->getOpcode() == BinaryOperator::Or) {
819 if (auto Opt = convertOrOfShiftsToFunnelShift(Or&: *Inst)) {
820 auto [IID, FShiftArgs] = *Opt;
821 if ((IID == Intrinsic::fshl || IID == Intrinsic::fshr) &&
822 FShiftArgs[0] == FShiftArgs[1]) {
823 llvm::computeKnownBits(V: I, Known, Q, Depth);
824 break;
825 }
826 }
827 }
828 }
829
830 // If we are just demanding the shifted sign bit and below, then this can
831 // be treated as an ASHR in disguise.
832 if (DemandedMask.countl_zero() >= ShiftAmt) {
833 // If we only want bits that already match the signbit then we don't
834 // need to shift.
835 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
836 unsigned SignBits =
837 ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
838 if (SignBits >= NumHiDemandedBits)
839 return I->getOperand(i: 0);
840
841 // If we can pre-shift a left-shifted constant to the right without
842 // losing any low bits (we already know we don't demand the high bits),
843 // then eliminate the right-shift:
844 // (C << X) >> RightShiftAmtC --> (C >> RightShiftAmtC) << X
845 Value *X;
846 Constant *C;
847 if (match(V: I->getOperand(i: 0), P: m_Shl(L: m_ImmConstant(C), R: m_Value(V&: X)))) {
848 Constant *RightShiftAmtC = ConstantInt::get(Ty: VTy, V: ShiftAmt);
849 Constant *NewC = ConstantFoldBinaryOpOperands(Opcode: Instruction::LShr, LHS: C,
850 RHS: RightShiftAmtC, DL);
851 if (ConstantFoldBinaryOpOperands(Opcode: Instruction::Shl, LHS: NewC,
852 RHS: RightShiftAmtC, DL) == C) {
853 Instruction *Shl = BinaryOperator::CreateShl(V1: NewC, V2: X);
854 return InsertNewInstWith(New: Shl, Old: I->getIterator());
855 }
856 }
857
858 const APInt *Factor;
859 if (match(V: I->getOperand(i: 0),
860 P: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: X), R: m_APInt(Res&: Factor)))) &&
861 Factor->countr_zero() >= ShiftAmt) {
862 BinaryOperator *Mul = BinaryOperator::CreateMul(
863 V1: X, V2: ConstantInt::get(Ty: X->getType(), V: Factor->lshr(shiftAmt: ShiftAmt)));
864 return InsertNewInstWith(New: Mul, Old: I->getIterator());
865 }
866 }
867
868 // Unsigned shift right.
869 APInt DemandedMaskIn(DemandedMask.shl(shiftAmt: ShiftAmt));
870 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1)) {
871 // exact flag may not longer hold.
872 I->dropPoisonGeneratingFlags();
873 return I;
874 }
875 Known >>= ShiftAmt;
876 if (ShiftAmt)
877 Known.Zero.setHighBits(ShiftAmt); // high bits known zero.
878 break;
879 }
880 if (Value *V =
881 simplifyShiftSelectingPackedElement(I, DemandedMask, IC&: *this, Depth))
882 return V;
883
884 llvm::computeKnownBits(V: I, Known, Q, Depth);
885 break;
886 }
887 case Instruction::AShr: {
888 unsigned SignBits = ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
889
890 // If we only want bits that already match the signbit then we don't need
891 // to shift.
892 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
893 if (SignBits >= NumHiDemandedBits)
894 return I->getOperand(i: 0);
895
896 // If this is an arithmetic shift right and only the low-bit is set, we can
897 // always convert this into a logical shr, even if the shift amount is
898 // variable. The low bit of the shift cannot be an input sign bit unless
899 // the shift amount is >= the size of the datatype, which is undefined.
900 if (DemandedMask.isOne()) {
901 // Perform the logical shift right.
902 Instruction *NewVal = BinaryOperator::CreateLShr(
903 V1: I->getOperand(i: 0), V2: I->getOperand(i: 1), Name: I->getName());
904 return InsertNewInstWith(New: NewVal, Old: I->getIterator());
905 }
906
907 const APInt *SA;
908 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
909 uint32_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth-1);
910
911 // Signed shift right.
912 APInt DemandedMaskIn(DemandedMask.shl(shiftAmt: ShiftAmt));
913 // If any of the bits being shifted in are demanded, then we should set
914 // the sign bit as demanded.
915 bool ShiftedInBitsDemanded = DemandedMask.countl_zero() < ShiftAmt;
916 if (ShiftedInBitsDemanded)
917 DemandedMaskIn.setSignBit();
918 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1)) {
919 // exact flag may not longer hold.
920 I->dropPoisonGeneratingFlags();
921 return I;
922 }
923
924 // If the input sign bit is known to be zero, or if none of the shifted in
925 // bits are demanded, turn this into an unsigned shift right.
926 if (Known.Zero[BitWidth - 1] || !ShiftedInBitsDemanded) {
927 BinaryOperator *LShr = BinaryOperator::CreateLShr(V1: I->getOperand(i: 0),
928 V2: I->getOperand(i: 1));
929 LShr->setIsExact(cast<BinaryOperator>(Val: I)->isExact());
930 LShr->takeName(V: I);
931 return InsertNewInstWith(New: LShr, Old: I->getIterator());
932 }
933
934 Known = KnownBits::ashr(
935 LHS: Known, RHS: KnownBits::makeConstant(C: APInt(BitWidth, ShiftAmt)),
936 ShAmtNonZero: ShiftAmt != 0, Exact: I->isExact());
937 } else {
938 llvm::computeKnownBits(V: I, Known, Q, Depth);
939 }
940 break;
941 }
942 case Instruction::UDiv: {
943 // UDiv doesn't demand low bits that are zero in the divisor.
944 const APInt *SA;
945 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
946 // TODO: Take the demanded mask of the result into account.
947 unsigned RHSTrailingZeros = SA->countr_zero();
948 APInt DemandedMaskIn =
949 APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - RHSTrailingZeros);
950 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known&: LHSKnown, Q, Depth: Depth + 1)) {
951 // We can't guarantee that "exact" is still true after changing the
952 // the dividend.
953 I->dropPoisonGeneratingFlags();
954 return I;
955 }
956
957 Known = KnownBits::udiv(LHS: LHSKnown, RHS: KnownBits::makeConstant(C: *SA),
958 Exact: cast<BinaryOperator>(Val: I)->isExact());
959 } else {
960 llvm::computeKnownBits(V: I, Known, Q, Depth);
961 }
962 break;
963 }
964 case Instruction::SRem: {
965 const APInt *Rem;
966 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: Rem)) && Rem->isPowerOf2()) {
967 if (DemandedMask.ult(RHS: *Rem)) // srem won't affect demanded bits
968 return I->getOperand(i: 0);
969
970 APInt LowBits = *Rem - 1;
971 APInt Mask2 = LowBits | APInt::getSignMask(BitWidth);
972 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: Mask2, Known&: LHSKnown, Q, Depth: Depth + 1))
973 return I;
974 Known = KnownBits::srem(LHS: LHSKnown, RHS: KnownBits::makeConstant(C: *Rem));
975 break;
976 }
977
978 llvm::computeKnownBits(V: I, Known, Q, Depth);
979 break;
980 }
981 case Instruction::Call: {
982 bool KnownBitsComputed = false;
983 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
984 switch (II->getIntrinsicID()) {
985 case Intrinsic::abs: {
986 if (DemandedMask == 1)
987 return II->getArgOperand(i: 0);
988 break;
989 }
990 case Intrinsic::ctpop: {
991 // Checking if the number of clear bits is odd (parity)? If the type has
992 // an even number of bits, that's the same as checking if the number of
993 // set bits is odd, so we can eliminate the 'not' op.
994 Value *X;
995 if (DemandedMask == 1 && VTy->getScalarSizeInBits() % 2 == 0 &&
996 match(V: II->getArgOperand(i: 0), P: m_Not(V: m_Value(V&: X)))) {
997 Function *Ctpop = Intrinsic::getOrInsertDeclaration(
998 M: II->getModule(), id: Intrinsic::ctpop, Tys: VTy);
999 return InsertNewInstWith(New: CallInst::Create(Func: Ctpop, Args: {X}), Old: I->getIterator());
1000 }
1001 break;
1002 }
1003 case Intrinsic::bswap: {
1004 // If the only bits demanded come from one byte of the bswap result,
1005 // just shift the input byte into position to eliminate the bswap.
1006 unsigned NLZ = DemandedMask.countl_zero();
1007 unsigned NTZ = DemandedMask.countr_zero();
1008
1009 // Round NTZ down to the next byte. If we have 11 trailing zeros, then
1010 // we need all the bits down to bit 8. Likewise, round NLZ. If we
1011 // have 14 leading zeros, round to 8.
1012 NLZ = alignDown(Value: NLZ, Align: 8);
1013 NTZ = alignDown(Value: NTZ, Align: 8);
1014 // If we need exactly one byte, we can do this transformation.
1015 if (BitWidth - NLZ - NTZ == 8) {
1016 // Replace this with either a left or right shift to get the byte into
1017 // the right place.
1018 Instruction *NewVal;
1019 if (NLZ > NTZ)
1020 NewVal = BinaryOperator::CreateLShr(
1021 V1: II->getArgOperand(i: 0), V2: ConstantInt::get(Ty: VTy, V: NLZ - NTZ));
1022 else
1023 NewVal = BinaryOperator::CreateShl(
1024 V1: II->getArgOperand(i: 0), V2: ConstantInt::get(Ty: VTy, V: NTZ - NLZ));
1025 NewVal->takeName(V: I);
1026 return InsertNewInstWith(New: NewVal, Old: I->getIterator());
1027 }
1028 break;
1029 }
1030 case Intrinsic::ptrmask: {
1031 unsigned MaskWidth = I->getOperand(i: 1)->getType()->getScalarSizeInBits();
1032 RHSKnown = KnownBits(MaskWidth);
1033 // If either the LHS or the RHS are Zero, the result is zero.
1034 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask, Known&: LHSKnown, Q, Depth: Depth + 1) ||
1035 SimplifyDemandedBits(
1036 I, OpNo: 1, DemandedMask: (DemandedMask & ~LHSKnown.Zero).zextOrTrunc(width: MaskWidth),
1037 Known&: RHSKnown, Q, Depth: Depth + 1))
1038 return I;
1039
1040 // TODO: Should be 1-extend
1041 RHSKnown = RHSKnown.anyextOrTrunc(BitWidth);
1042
1043 Known = LHSKnown & RHSKnown;
1044 KnownBitsComputed = true;
1045
1046 // If the client is only demanding bits we know to be zero, return
1047 // `llvm.ptrmask(p, 0)`. We can't return `null` here due to pointer
1048 // provenance, but making the mask zero will be easily optimizable in
1049 // the backend.
1050 if (DemandedMask.isSubsetOf(RHS: Known.Zero) &&
1051 !match(V: I->getOperand(i: 1), P: m_Zero()))
1052 return replaceOperand(
1053 I&: *I, OpNum: 1, V: Constant::getNullValue(Ty: I->getOperand(i: 1)->getType()));
1054
1055 // Mask in demanded space does nothing.
1056 // NOTE: We may have attributes associated with the return value of the
1057 // llvm.ptrmask intrinsic that will be lost when we just return the
1058 // operand. We should try to preserve them.
1059 if (DemandedMask.isSubsetOf(RHS: RHSKnown.One | LHSKnown.Zero))
1060 return I->getOperand(i: 0);
1061
1062 // If the RHS is a constant, see if we can simplify it.
1063 if (ShrinkDemandedConstant(
1064 I, OpNo: 1, Demanded: (DemandedMask & ~LHSKnown.Zero).zextOrTrunc(width: MaskWidth)))
1065 return I;
1066
1067 // Combine:
1068 // (ptrmask (getelementptr i8, ptr p, imm i), imm mask)
1069 // -> (ptrmask (getelementptr i8, ptr p, imm (i & mask)), imm mask)
1070 // where only the low bits known to be zero in the pointer are changed
1071 Value *InnerPtr;
1072 uint64_t GEPIndex;
1073 uint64_t PtrMaskImmediate;
1074 if (match(V: I, P: m_Intrinsic<Intrinsic::ptrmask>(
1075 Op0: m_PtrAdd(PointerOp: m_Value(V&: InnerPtr), OffsetOp: m_ConstantInt(V&: GEPIndex)),
1076 Op1: m_ConstantInt(V&: PtrMaskImmediate)))) {
1077
1078 LHSKnown = computeKnownBits(V: InnerPtr, CxtI: I, Depth: Depth + 1);
1079 if (!LHSKnown.isZero()) {
1080 const unsigned trailingZeros = LHSKnown.countMinTrailingZeros();
1081 uint64_t PointerAlignBits = (uint64_t(1) << trailingZeros) - 1;
1082
1083 uint64_t HighBitsGEPIndex = GEPIndex & ~PointerAlignBits;
1084 uint64_t MaskedLowBitsGEPIndex =
1085 GEPIndex & PointerAlignBits & PtrMaskImmediate;
1086
1087 uint64_t MaskedGEPIndex = HighBitsGEPIndex | MaskedLowBitsGEPIndex;
1088
1089 if (MaskedGEPIndex != GEPIndex) {
1090 auto *GEP = cast<GEPOperator>(Val: II->getArgOperand(i: 0));
1091 Builder.SetInsertPoint(I);
1092 Type *GEPIndexType =
1093 DL.getIndexType(PtrTy: GEP->getPointerOperand()->getType());
1094 Value *MaskedGEP = Builder.CreateGEP(
1095 Ty: GEP->getSourceElementType(), Ptr: InnerPtr,
1096 IdxList: ConstantInt::get(Ty: GEPIndexType, V: MaskedGEPIndex),
1097 Name: GEP->getName(), NW: GEP->isInBounds());
1098
1099 replaceOperand(I&: *I, OpNum: 0, V: MaskedGEP);
1100 return I;
1101 }
1102 }
1103 }
1104
1105 break;
1106 }
1107
1108 case Intrinsic::fshr:
1109 case Intrinsic::fshl: {
1110 const APInt *SA;
1111 if (!match(V: I->getOperand(i: 2), P: m_APInt(Res&: SA)))
1112 break;
1113
1114 // Normalize to funnel shift left. APInt shifts of BitWidth are well-
1115 // defined, so no need to special-case zero shifts here.
1116 uint64_t ShiftAmt = SA->urem(RHS: BitWidth);
1117 if (II->getIntrinsicID() == Intrinsic::fshr)
1118 ShiftAmt = BitWidth - ShiftAmt;
1119
1120 APInt DemandedMaskLHS(DemandedMask.lshr(shiftAmt: ShiftAmt));
1121 APInt DemandedMaskRHS(DemandedMask.shl(shiftAmt: BitWidth - ShiftAmt));
1122 if (I->getOperand(i: 0) != I->getOperand(i: 1)) {
1123 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskLHS, Known&: LHSKnown, Q,
1124 Depth: Depth + 1) ||
1125 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedMaskRHS, Known&: RHSKnown, Q,
1126 Depth: Depth + 1)) {
1127 // Range attribute or metadata may no longer hold.
1128 I->dropPoisonGeneratingAnnotations();
1129 return I;
1130 }
1131 } else { // fshl is a rotate
1132 // Avoid converting rotate into funnel shift.
1133 // Only simplify if one operand is constant.
1134 LHSKnown = computeKnownBits(V: I->getOperand(i: 0), CxtI: I, Depth: Depth + 1);
1135 if (DemandedMaskLHS.isSubsetOf(RHS: LHSKnown.Zero | LHSKnown.One) &&
1136 !match(V: I->getOperand(i: 0), P: m_SpecificInt(V: LHSKnown.One))) {
1137 replaceOperand(I&: *I, OpNum: 0, V: Constant::getIntegerValue(Ty: VTy, V: LHSKnown.One));
1138 return I;
1139 }
1140
1141 RHSKnown = computeKnownBits(V: I->getOperand(i: 1), CxtI: I, Depth: Depth + 1);
1142 if (DemandedMaskRHS.isSubsetOf(RHS: RHSKnown.Zero | RHSKnown.One) &&
1143 !match(V: I->getOperand(i: 1), P: m_SpecificInt(V: RHSKnown.One))) {
1144 replaceOperand(I&: *I, OpNum: 1, V: Constant::getIntegerValue(Ty: VTy, V: RHSKnown.One));
1145 return I;
1146 }
1147 }
1148
1149 LHSKnown <<= ShiftAmt;
1150 RHSKnown >>= BitWidth - ShiftAmt;
1151 Known = LHSKnown.unionWith(RHS: RHSKnown);
1152 KnownBitsComputed = true;
1153 break;
1154 }
1155 case Intrinsic::umax: {
1156 // UMax(A, C) == A if ...
1157 // The lowest non-zero bit of DemandMask is higher than the highest
1158 // non-zero bit of C.
1159 const APInt *C;
1160 unsigned CTZ = DemandedMask.countr_zero();
1161 if (match(V: II->getArgOperand(i: 1), P: m_APInt(Res&: C)) &&
1162 CTZ >= C->getActiveBits())
1163 return II->getArgOperand(i: 0);
1164 break;
1165 }
1166 case Intrinsic::umin: {
1167 // UMin(A, C) == A if ...
1168 // The lowest non-zero bit of DemandMask is higher than the highest
1169 // non-one bit of C.
1170 // This comes from using DeMorgans on the above umax example.
1171 const APInt *C;
1172 unsigned CTZ = DemandedMask.countr_zero();
1173 if (match(V: II->getArgOperand(i: 1), P: m_APInt(Res&: C)) &&
1174 CTZ >= C->getBitWidth() - C->countl_one())
1175 return II->getArgOperand(i: 0);
1176 break;
1177 }
1178 default: {
1179 // Handle target specific intrinsics
1180 std::optional<Value *> V = targetSimplifyDemandedUseBitsIntrinsic(
1181 II&: *II, DemandedMask, Known, KnownBitsComputed);
1182 if (V)
1183 return *V;
1184 break;
1185 }
1186 }
1187 }
1188
1189 if (!KnownBitsComputed)
1190 llvm::computeKnownBits(V: I, Known, Q, Depth);
1191 break;
1192 }
1193 }
1194
1195 if (I->getType()->isPointerTy()) {
1196 Align Alignment = I->getPointerAlignment(DL);
1197 Known.Zero.setLowBits(Log2(A: Alignment));
1198 }
1199
1200 // If the client is only demanding bits that we know, return the known
1201 // constant. We can't directly simplify pointers as a constant because of
1202 // pointer provenance.
1203 // TODO: We could return `(inttoptr const)` for pointers.
1204 if (!I->getType()->isPointerTy() &&
1205 DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1206 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
1207
1208 if (VerifyKnownBits) {
1209 KnownBits ReferenceKnown = llvm::computeKnownBits(V: I, Q, Depth);
1210 if (Known != ReferenceKnown) {
1211 errs() << "Mismatched known bits for " << *I << " in "
1212 << I->getFunction()->getName() << "\n";
1213 errs() << "computeKnownBits(): " << ReferenceKnown << "\n";
1214 errs() << "SimplifyDemandedBits(): " << Known << "\n";
1215 std::abort();
1216 }
1217 }
1218
1219 return nullptr;
1220}
1221
1222/// Helper routine of SimplifyDemandedUseBits. It computes Known
1223/// bits. It also tries to handle simplifications that can be done based on
1224/// DemandedMask, but without modifying the Instruction.
1225Value *InstCombinerImpl::SimplifyMultipleUseDemandedBits(
1226 Instruction *I, const APInt &DemandedMask, KnownBits &Known,
1227 const SimplifyQuery &Q, unsigned Depth) {
1228 unsigned BitWidth = DemandedMask.getBitWidth();
1229 Type *ITy = I->getType();
1230
1231 KnownBits LHSKnown(BitWidth);
1232 KnownBits RHSKnown(BitWidth);
1233
1234 // Despite the fact that we can't simplify this instruction in all User's
1235 // context, we can at least compute the known bits, and we can
1236 // do simplifications that apply to *just* the one user if we know that
1237 // this instruction has a simpler value in that context.
1238 switch (I->getOpcode()) {
1239 case Instruction::And: {
1240 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1241 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1242 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1243 SQ: Q, Depth);
1244 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1245
1246 // If the client is only demanding bits that we know, return the known
1247 // constant.
1248 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1249 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1250
1251 // If all of the demanded bits are known 1 on one side, return the other.
1252 // These bits cannot contribute to the result of the 'and' in this context.
1253 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero | RHSKnown.One))
1254 return I->getOperand(i: 0);
1255 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero | LHSKnown.One))
1256 return I->getOperand(i: 1);
1257
1258 break;
1259 }
1260 case Instruction::Or: {
1261 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1262 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1263 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1264 SQ: Q, Depth);
1265 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1266
1267 // If the client is only demanding bits that we know, return the known
1268 // constant.
1269 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1270 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1271
1272 // We can simplify (X|Y) -> X or Y in the user's context if we know that
1273 // only bits from X or Y are demanded.
1274 // If all of the demanded bits are known zero on one side, return the other.
1275 // These bits cannot contribute to the result of the 'or' in this context.
1276 if (DemandedMask.isSubsetOf(RHS: LHSKnown.One | RHSKnown.Zero))
1277 return I->getOperand(i: 0);
1278 if (DemandedMask.isSubsetOf(RHS: RHSKnown.One | LHSKnown.Zero))
1279 return I->getOperand(i: 1);
1280
1281 break;
1282 }
1283 case Instruction::Xor: {
1284 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1285 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1286 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1287 SQ: Q, Depth);
1288 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1289
1290 // If the client is only demanding bits that we know, return the known
1291 // constant.
1292 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1293 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1294
1295 // We can simplify (X^Y) -> X or Y in the user's context if we know that
1296 // only bits from X or Y are demanded.
1297 // If all of the demanded bits are known zero on one side, return the other.
1298 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero))
1299 return I->getOperand(i: 0);
1300 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero))
1301 return I->getOperand(i: 1);
1302
1303 break;
1304 }
1305 case Instruction::Add: {
1306 unsigned NLZ = DemandedMask.countl_zero();
1307 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
1308
1309 // If an operand adds zeros to every bit below the highest demanded bit,
1310 // that operand doesn't change the result. Return the other side.
1311 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1312 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
1313 return I->getOperand(i: 0);
1314
1315 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1316 if (DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
1317 return I->getOperand(i: 1);
1318
1319 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
1320 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
1321 Known = KnownBits::add(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
1322 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1323 break;
1324 }
1325 case Instruction::Sub: {
1326 unsigned NLZ = DemandedMask.countl_zero();
1327 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
1328
1329 // If an operand subtracts zeros from every bit below the highest demanded
1330 // bit, that operand doesn't change the result. Return the other side.
1331 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1332 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
1333 return I->getOperand(i: 0);
1334
1335 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
1336 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
1337 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1338 Known = KnownBits::sub(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
1339 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1340 break;
1341 }
1342 case Instruction::AShr: {
1343 // Compute the Known bits to simplify things downstream.
1344 llvm::computeKnownBits(V: I, Known, Q, Depth);
1345
1346 // If this user is only demanding bits that we know, return the known
1347 // constant.
1348 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1349 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1350
1351 // If the right shift operand 0 is a result of a left shift by the same
1352 // amount, this is probably a zero/sign extension, which may be unnecessary,
1353 // if we do not demand any of the new sign bits. So, return the original
1354 // operand instead.
1355 const APInt *ShiftRC;
1356 const APInt *ShiftLC;
1357 Value *X;
1358 unsigned BitWidth = DemandedMask.getBitWidth();
1359 if (match(V: I,
1360 P: m_AShr(L: m_Shl(L: m_Value(V&: X), R: m_APInt(Res&: ShiftLC)), R: m_APInt(Res&: ShiftRC))) &&
1361 ShiftLC == ShiftRC && ShiftLC->ult(RHS: BitWidth) &&
1362 DemandedMask.isSubsetOf(RHS: APInt::getLowBitsSet(
1363 numBits: BitWidth, loBitsSet: BitWidth - ShiftRC->getZExtValue()))) {
1364 return X;
1365 }
1366
1367 break;
1368 }
1369 default:
1370 // Compute the Known bits to simplify things downstream.
1371 llvm::computeKnownBits(V: I, Known, Q, Depth);
1372
1373 // If this user is only demanding bits that we know, return the known
1374 // constant.
1375 if (DemandedMask.isSubsetOf(RHS: Known.Zero|Known.One))
1376 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1377
1378 break;
1379 }
1380
1381 return nullptr;
1382}
1383
1384/// Helper routine of SimplifyDemandedUseBits. It tries to simplify
1385/// "E1 = (X lsr C1) << C2", where the C1 and C2 are constant, into
1386/// "E2 = X << (C2 - C1)" or "E2 = X >> (C1 - C2)", depending on the sign
1387/// of "C2-C1".
1388///
1389/// Suppose E1 and E2 are generally different in bits S={bm, bm+1,
1390/// ..., bn}, without considering the specific value X is holding.
1391/// This transformation is legal iff one of following conditions is hold:
1392/// 1) All the bit in S are 0, in this case E1 == E2.
1393/// 2) We don't care those bits in S, per the input DemandedMask.
1394/// 3) Combination of 1) and 2). Some bits in S are 0, and we don't care the
1395/// rest bits.
1396///
1397/// Currently we only test condition 2).
1398///
1399/// As with SimplifyDemandedUseBits, it returns NULL if the simplification was
1400/// not successful.
1401Value *InstCombinerImpl::simplifyShrShlDemandedBits(
1402 Instruction *Shr, const APInt &ShrOp1, Instruction *Shl,
1403 const APInt &ShlOp1, const APInt &DemandedMask, KnownBits &Known) {
1404 if (!ShlOp1 || !ShrOp1)
1405 return nullptr; // No-op.
1406
1407 Value *VarX = Shr->getOperand(i: 0);
1408 Type *Ty = VarX->getType();
1409 unsigned BitWidth = Ty->getScalarSizeInBits();
1410 if (ShlOp1.uge(RHS: BitWidth) || ShrOp1.uge(RHS: BitWidth))
1411 return nullptr; // Undef.
1412
1413 unsigned ShlAmt = ShlOp1.getZExtValue();
1414 unsigned ShrAmt = ShrOp1.getZExtValue();
1415
1416 Known.One.clearAllBits();
1417 Known.Zero.setLowBits(ShlAmt - 1);
1418 Known.Zero &= DemandedMask;
1419
1420 APInt BitMask1(APInt::getAllOnes(numBits: BitWidth));
1421 APInt BitMask2(APInt::getAllOnes(numBits: BitWidth));
1422
1423 bool isLshr = (Shr->getOpcode() == Instruction::LShr);
1424 BitMask1 = isLshr ? (BitMask1.lshr(shiftAmt: ShrAmt) << ShlAmt) :
1425 (BitMask1.ashr(ShiftAmt: ShrAmt) << ShlAmt);
1426
1427 if (ShrAmt <= ShlAmt) {
1428 BitMask2 <<= (ShlAmt - ShrAmt);
1429 } else {
1430 BitMask2 = isLshr ? BitMask2.lshr(shiftAmt: ShrAmt - ShlAmt):
1431 BitMask2.ashr(ShiftAmt: ShrAmt - ShlAmt);
1432 }
1433
1434 // Check if condition-2 (see the comment to this function) is satified.
1435 if ((BitMask1 & DemandedMask) == (BitMask2 & DemandedMask)) {
1436 if (ShrAmt == ShlAmt)
1437 return VarX;
1438
1439 if (!Shr->hasOneUse())
1440 return nullptr;
1441
1442 BinaryOperator *New;
1443 if (ShrAmt < ShlAmt) {
1444 Constant *Amt = ConstantInt::get(Ty: VarX->getType(), V: ShlAmt - ShrAmt);
1445 New = BinaryOperator::CreateShl(V1: VarX, V2: Amt);
1446 BinaryOperator *Orig = cast<BinaryOperator>(Val: Shl);
1447 New->setHasNoSignedWrap(Orig->hasNoSignedWrap());
1448 New->setHasNoUnsignedWrap(Orig->hasNoUnsignedWrap());
1449 } else {
1450 Constant *Amt = ConstantInt::get(Ty: VarX->getType(), V: ShrAmt - ShlAmt);
1451 New = isLshr ? BinaryOperator::CreateLShr(V1: VarX, V2: Amt) :
1452 BinaryOperator::CreateAShr(V1: VarX, V2: Amt);
1453 if (cast<BinaryOperator>(Val: Shr)->isExact())
1454 New->setIsExact(true);
1455 }
1456
1457 return InsertNewInstWith(New, Old: Shl->getIterator());
1458 }
1459
1460 return nullptr;
1461}
1462
1463/// The specified value produces a vector with any number of elements.
1464/// This method analyzes which elements of the operand are poison and
1465/// returns that information in PoisonElts.
1466///
1467/// DemandedElts contains the set of elements that are actually used by the
1468/// caller, and by default (AllowMultipleUsers equals false) the value is
1469/// simplified only if it has a single caller. If AllowMultipleUsers is set
1470/// to true, DemandedElts refers to the union of sets of elements that are
1471/// used by all callers.
1472///
1473/// If the information about demanded elements can be used to simplify the
1474/// operation, the operation is simplified, then the resultant value is
1475/// returned. This returns null if no change was made.
1476Value *InstCombinerImpl::SimplifyDemandedVectorElts(Value *V,
1477 APInt DemandedElts,
1478 APInt &PoisonElts,
1479 unsigned Depth,
1480 bool AllowMultipleUsers) {
1481 // Cannot analyze scalable type. The number of vector elements is not a
1482 // compile-time constant.
1483 if (isa<ScalableVectorType>(Val: V->getType()))
1484 return nullptr;
1485
1486 unsigned VWidth = cast<FixedVectorType>(Val: V->getType())->getNumElements();
1487 APInt EltMask(APInt::getAllOnes(numBits: VWidth));
1488 assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
1489
1490 if (match(V, P: m_Poison())) {
1491 // If the entire vector is poison, just return this info.
1492 PoisonElts = EltMask;
1493 return nullptr;
1494 }
1495
1496 if (DemandedElts.isZero()) { // If nothing is demanded, provide poison.
1497 PoisonElts = EltMask;
1498 return PoisonValue::get(T: V->getType());
1499 }
1500
1501 PoisonElts = 0;
1502
1503 if (auto *C = dyn_cast<Constant>(Val: V)) {
1504 // Check if this is identity. If so, return 0 since we are not simplifying
1505 // anything.
1506 if (DemandedElts.isAllOnes())
1507 return nullptr;
1508
1509 Type *EltTy = cast<VectorType>(Val: V->getType())->getElementType();
1510 Constant *Poison = PoisonValue::get(T: EltTy);
1511 SmallVector<Constant*, 16> Elts;
1512 for (unsigned i = 0; i != VWidth; ++i) {
1513 if (!DemandedElts[i]) { // If not demanded, set to poison.
1514 Elts.push_back(Elt: Poison);
1515 PoisonElts.setBit(i);
1516 continue;
1517 }
1518
1519 Constant *Elt = C->getAggregateElement(Elt: i);
1520 if (!Elt) return nullptr;
1521
1522 Elts.push_back(Elt);
1523 if (isa<PoisonValue>(Val: Elt)) // Already poison.
1524 PoisonElts.setBit(i);
1525 }
1526
1527 // If we changed the constant, return it.
1528 Constant *NewCV = ConstantVector::get(V: Elts);
1529 return NewCV != C ? NewCV : nullptr;
1530 }
1531
1532 // Limit search depth.
1533 if (Depth == SimplifyDemandedVectorEltsDepthLimit)
1534 return nullptr;
1535
1536 if (!AllowMultipleUsers) {
1537 // If multiple users are using the root value, proceed with
1538 // simplification conservatively assuming that all elements
1539 // are needed.
1540 if (!V->hasOneUse()) {
1541 // Quit if we find multiple users of a non-root value though.
1542 // They'll be handled when it's their turn to be visited by
1543 // the main instcombine process.
1544 if (Depth != 0)
1545 // TODO: Just compute the PoisonElts information recursively.
1546 return nullptr;
1547
1548 // Conservatively assume that all elements are needed.
1549 DemandedElts = EltMask;
1550 }
1551 }
1552
1553 Instruction *I = dyn_cast<Instruction>(Val: V);
1554 if (!I) return nullptr; // Only analyze instructions.
1555
1556 bool MadeChange = false;
1557 auto simplifyAndSetOp = [&](Instruction *Inst, unsigned OpNum,
1558 APInt Demanded, APInt &Undef) {
1559 auto *II = dyn_cast<IntrinsicInst>(Val: Inst);
1560 Value *Op = II ? II->getArgOperand(i: OpNum) : Inst->getOperand(i: OpNum);
1561 if (Value *V = SimplifyDemandedVectorElts(V: Op, DemandedElts: Demanded, PoisonElts&: Undef, Depth: Depth + 1)) {
1562 replaceOperand(I&: *Inst, OpNum, V);
1563 MadeChange = true;
1564 }
1565 };
1566
1567 APInt PoisonElts2(VWidth, 0);
1568 APInt PoisonElts3(VWidth, 0);
1569 switch (I->getOpcode()) {
1570 default: break;
1571
1572 case Instruction::GetElementPtr: {
1573 // The LangRef requires that struct geps have all constant indices. As
1574 // such, we can't convert any operand to partial undef.
1575 auto mayIndexStructType = [](GetElementPtrInst &GEP) {
1576 for (auto I = gep_type_begin(GEP), E = gep_type_end(GEP);
1577 I != E; I++)
1578 if (I.isStruct())
1579 return true;
1580 return false;
1581 };
1582 if (mayIndexStructType(cast<GetElementPtrInst>(Val&: *I)))
1583 break;
1584
1585 // Conservatively track the demanded elements back through any vector
1586 // operands we may have. We know there must be at least one, or we
1587 // wouldn't have a vector result to get here. Note that we intentionally
1588 // merge the undef bits here since gepping with either an poison base or
1589 // index results in poison.
1590 for (unsigned i = 0; i < I->getNumOperands(); i++) {
1591 if (i == 0 ? match(V: I->getOperand(i), P: m_Undef())
1592 : match(V: I->getOperand(i), P: m_Poison())) {
1593 // If the entire vector is undefined, just return this info.
1594 PoisonElts = EltMask;
1595 return nullptr;
1596 }
1597 if (I->getOperand(i)->getType()->isVectorTy()) {
1598 APInt PoisonEltsOp(VWidth, 0);
1599 simplifyAndSetOp(I, i, DemandedElts, PoisonEltsOp);
1600 // gep(x, undef) is not undef, so skip considering idx ops here
1601 // Note that we could propagate poison, but we can't distinguish between
1602 // undef & poison bits ATM
1603 if (i == 0)
1604 PoisonElts |= PoisonEltsOp;
1605 }
1606 }
1607
1608 break;
1609 }
1610 case Instruction::InsertElement: {
1611 // If this is a variable index, we don't know which element it overwrites.
1612 // demand exactly the same input as we produce.
1613 ConstantInt *Idx = dyn_cast<ConstantInt>(Val: I->getOperand(i: 2));
1614 if (!Idx) {
1615 // Note that we can't propagate undef elt info, because we don't know
1616 // which elt is getting updated.
1617 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts2);
1618 break;
1619 }
1620
1621 // The element inserted overwrites whatever was there, so the input demanded
1622 // set is simpler than the output set.
1623 unsigned IdxNo = Idx->getZExtValue();
1624 APInt PreInsertDemandedElts = DemandedElts;
1625 if (IdxNo < VWidth)
1626 PreInsertDemandedElts.clearBit(BitPosition: IdxNo);
1627
1628 // If we only demand the element that is being inserted and that element
1629 // was extracted from the same index in another vector with the same type,
1630 // replace this insert with that other vector.
1631 // Note: This is attempted before the call to simplifyAndSetOp because that
1632 // may change PoisonElts to a value that does not match with Vec.
1633 Value *Vec;
1634 if (PreInsertDemandedElts == 0 &&
1635 match(V: I->getOperand(i: 1),
1636 P: m_ExtractElt(Val: m_Value(V&: Vec), Idx: m_SpecificInt(V: IdxNo))) &&
1637 Vec->getType() == I->getType()) {
1638 return Vec;
1639 }
1640
1641 simplifyAndSetOp(I, 0, PreInsertDemandedElts, PoisonElts);
1642
1643 // If this is inserting an element that isn't demanded, remove this
1644 // insertelement.
1645 if (IdxNo >= VWidth || !DemandedElts[IdxNo]) {
1646 Worklist.push(I);
1647 return I->getOperand(i: 0);
1648 }
1649
1650 // The inserted element is defined.
1651 PoisonElts.clearBit(BitPosition: IdxNo);
1652 break;
1653 }
1654 case Instruction::ShuffleVector: {
1655 auto *Shuffle = cast<ShuffleVectorInst>(Val: I);
1656 assert(Shuffle->getOperand(0)->getType() ==
1657 Shuffle->getOperand(1)->getType() &&
1658 "Expected shuffle operands to have same type");
1659 unsigned OpWidth = cast<FixedVectorType>(Val: Shuffle->getOperand(i_nocapture: 0)->getType())
1660 ->getNumElements();
1661 // Handle trivial case of a splat. Only check the first element of LHS
1662 // operand.
1663 if (all_of(Range: Shuffle->getShuffleMask(), P: equal_to(Arg: 0)) &&
1664 DemandedElts.isAllOnes()) {
1665 if (!isa<PoisonValue>(Val: I->getOperand(i: 1))) {
1666 I->setOperand(i: 1, Val: PoisonValue::get(T: I->getOperand(i: 1)->getType()));
1667 MadeChange = true;
1668 }
1669 APInt LeftDemanded(OpWidth, 1);
1670 APInt LHSPoisonElts(OpWidth, 0);
1671 simplifyAndSetOp(I, 0, LeftDemanded, LHSPoisonElts);
1672 if (LHSPoisonElts[0])
1673 PoisonElts = EltMask;
1674 else
1675 PoisonElts.clearAllBits();
1676 break;
1677 }
1678
1679 APInt LeftDemanded(OpWidth, 0), RightDemanded(OpWidth, 0);
1680 for (unsigned i = 0; i < VWidth; i++) {
1681 if (DemandedElts[i]) {
1682 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1683 if (MaskVal != -1u) {
1684 assert(MaskVal < OpWidth * 2 &&
1685 "shufflevector mask index out of range!");
1686 if (MaskVal < OpWidth)
1687 LeftDemanded.setBit(MaskVal);
1688 else
1689 RightDemanded.setBit(MaskVal - OpWidth);
1690 }
1691 }
1692 }
1693
1694 APInt LHSPoisonElts(OpWidth, 0);
1695 simplifyAndSetOp(I, 0, LeftDemanded, LHSPoisonElts);
1696
1697 APInt RHSPoisonElts(OpWidth, 0);
1698 simplifyAndSetOp(I, 1, RightDemanded, RHSPoisonElts);
1699
1700 // If this shuffle does not change the vector length and the elements
1701 // demanded by this shuffle are an identity mask, then this shuffle is
1702 // unnecessary.
1703 //
1704 // We are assuming canonical form for the mask, so the source vector is
1705 // operand 0 and operand 1 is not used.
1706 //
1707 // Note that if an element is demanded and this shuffle mask is undefined
1708 // for that element, then the shuffle is not considered an identity
1709 // operation. The shuffle prevents poison from the operand vector from
1710 // leaking to the result by replacing poison with an undefined value.
1711 if (VWidth == OpWidth) {
1712 bool IsIdentityShuffle = true;
1713 for (unsigned i = 0; i < VWidth; i++) {
1714 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1715 if (DemandedElts[i] && i != MaskVal) {
1716 IsIdentityShuffle = false;
1717 break;
1718 }
1719 }
1720 if (IsIdentityShuffle)
1721 return Shuffle->getOperand(i_nocapture: 0);
1722 }
1723
1724 bool NewPoisonElts = false;
1725 unsigned LHSIdx = -1u, LHSValIdx = -1u;
1726 unsigned RHSIdx = -1u, RHSValIdx = -1u;
1727 bool LHSUniform = true;
1728 bool RHSUniform = true;
1729 for (unsigned i = 0; i < VWidth; i++) {
1730 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1731 if (MaskVal == -1u) {
1732 PoisonElts.setBit(i);
1733 } else if (!DemandedElts[i]) {
1734 NewPoisonElts = true;
1735 PoisonElts.setBit(i);
1736 } else if (MaskVal < OpWidth) {
1737 if (LHSPoisonElts[MaskVal]) {
1738 NewPoisonElts = true;
1739 PoisonElts.setBit(i);
1740 } else {
1741 LHSIdx = LHSIdx == -1u ? i : OpWidth;
1742 LHSValIdx = LHSValIdx == -1u ? MaskVal : OpWidth;
1743 LHSUniform = LHSUniform && (MaskVal == i);
1744 }
1745 } else {
1746 if (RHSPoisonElts[MaskVal - OpWidth]) {
1747 NewPoisonElts = true;
1748 PoisonElts.setBit(i);
1749 } else {
1750 RHSIdx = RHSIdx == -1u ? i : OpWidth;
1751 RHSValIdx = RHSValIdx == -1u ? MaskVal - OpWidth : OpWidth;
1752 RHSUniform = RHSUniform && (MaskVal - OpWidth == i);
1753 }
1754 }
1755 }
1756
1757 // Try to transform shuffle with constant vector and single element from
1758 // this constant vector to single insertelement instruction.
1759 // shufflevector V, C, <v1, v2, .., ci, .., vm> ->
1760 // insertelement V, C[ci], ci-n
1761 if (OpWidth ==
1762 cast<FixedVectorType>(Val: Shuffle->getType())->getNumElements()) {
1763 Value *Op = nullptr;
1764 Constant *Value = nullptr;
1765 unsigned Idx = -1u;
1766
1767 // Find constant vector with the single element in shuffle (LHS or RHS).
1768 if (LHSIdx < OpWidth && RHSUniform) {
1769 if (auto *CV = dyn_cast<ConstantVector>(Val: Shuffle->getOperand(i_nocapture: 0))) {
1770 Op = Shuffle->getOperand(i_nocapture: 1);
1771 Value = CV->getOperand(i_nocapture: LHSValIdx);
1772 Idx = LHSIdx;
1773 }
1774 }
1775 if (RHSIdx < OpWidth && LHSUniform) {
1776 if (auto *CV = dyn_cast<ConstantVector>(Val: Shuffle->getOperand(i_nocapture: 1))) {
1777 Op = Shuffle->getOperand(i_nocapture: 0);
1778 Value = CV->getOperand(i_nocapture: RHSValIdx);
1779 Idx = RHSIdx;
1780 }
1781 }
1782 // Found constant vector with single element - convert to insertelement.
1783 if (Op && Value) {
1784 Instruction *New = InsertElementInst::Create(
1785 Vec: Op, NewElt: Value, Idx: ConstantInt::get(Ty: Type::getInt64Ty(C&: I->getContext()), V: Idx),
1786 NameStr: Shuffle->getName());
1787 InsertNewInstWith(New, Old: Shuffle->getIterator());
1788 return New;
1789 }
1790 }
1791 if (NewPoisonElts) {
1792 // Add additional discovered undefs.
1793 SmallVector<int, 16> Elts;
1794 for (unsigned i = 0; i < VWidth; ++i) {
1795 if (PoisonElts[i])
1796 Elts.push_back(Elt: PoisonMaskElem);
1797 else
1798 Elts.push_back(Elt: Shuffle->getMaskValue(Elt: i));
1799 }
1800 Shuffle->setShuffleMask(Elts);
1801 MadeChange = true;
1802 }
1803 break;
1804 }
1805 case Instruction::Select: {
1806 // If this is a vector select, try to transform the select condition based
1807 // on the current demanded elements.
1808 SelectInst *Sel = cast<SelectInst>(Val: I);
1809 if (Sel->getCondition()->getType()->isVectorTy()) {
1810 // TODO: We are not doing anything with PoisonElts based on this call.
1811 // It is overwritten below based on the other select operands. If an
1812 // element of the select condition is known undef, then we are free to
1813 // choose the output value from either arm of the select. If we know that
1814 // one of those values is undef, then the output can be undef.
1815 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
1816 }
1817
1818 // Next, see if we can transform the arms of the select.
1819 APInt DemandedLHS(DemandedElts), DemandedRHS(DemandedElts);
1820 if (auto *CV = dyn_cast<ConstantVector>(Val: Sel->getCondition())) {
1821 for (unsigned i = 0; i < VWidth; i++) {
1822 Constant *CElt = CV->getAggregateElement(Elt: i);
1823
1824 // isNullValue() always returns false when called on a ConstantExpr.
1825 if (CElt->isNullValue())
1826 DemandedLHS.clearBit(BitPosition: i);
1827 else if (CElt->isOneValue())
1828 DemandedRHS.clearBit(BitPosition: i);
1829 }
1830 }
1831
1832 simplifyAndSetOp(I, 1, DemandedLHS, PoisonElts2);
1833 simplifyAndSetOp(I, 2, DemandedRHS, PoisonElts3);
1834
1835 // Output elements are undefined if the element from each arm is undefined.
1836 // TODO: This can be improved. See comment in select condition handling.
1837 PoisonElts = PoisonElts2 & PoisonElts3;
1838 break;
1839 }
1840 case Instruction::BitCast: {
1841 // Vector->vector casts only.
1842 VectorType *VTy = dyn_cast<VectorType>(Val: I->getOperand(i: 0)->getType());
1843 if (!VTy) break;
1844 unsigned InVWidth = cast<FixedVectorType>(Val: VTy)->getNumElements();
1845 APInt InputDemandedElts(InVWidth, 0);
1846 PoisonElts2 = APInt(InVWidth, 0);
1847 unsigned Ratio;
1848
1849 if (VWidth == InVWidth) {
1850 // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
1851 // elements as are demanded of us.
1852 Ratio = 1;
1853 InputDemandedElts = DemandedElts;
1854 } else if ((VWidth % InVWidth) == 0) {
1855 // If the number of elements in the output is a multiple of the number of
1856 // elements in the input then an input element is live if any of the
1857 // corresponding output elements are live.
1858 Ratio = VWidth / InVWidth;
1859 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1860 if (DemandedElts[OutIdx])
1861 InputDemandedElts.setBit(OutIdx / Ratio);
1862 } else if ((InVWidth % VWidth) == 0) {
1863 // If the number of elements in the input is a multiple of the number of
1864 // elements in the output then an input element is live if the
1865 // corresponding output element is live.
1866 Ratio = InVWidth / VWidth;
1867 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1868 if (DemandedElts[InIdx / Ratio])
1869 InputDemandedElts.setBit(InIdx);
1870 } else {
1871 // Unsupported so far.
1872 break;
1873 }
1874
1875 simplifyAndSetOp(I, 0, InputDemandedElts, PoisonElts2);
1876
1877 if (VWidth == InVWidth) {
1878 PoisonElts = PoisonElts2;
1879 } else if ((VWidth % InVWidth) == 0) {
1880 // If the number of elements in the output is a multiple of the number of
1881 // elements in the input then an output element is undef if the
1882 // corresponding input element is undef.
1883 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1884 if (PoisonElts2[OutIdx / Ratio])
1885 PoisonElts.setBit(OutIdx);
1886 } else if ((InVWidth % VWidth) == 0) {
1887 // If the number of elements in the input is a multiple of the number of
1888 // elements in the output then an output element is undef if all of the
1889 // corresponding input elements are undef.
1890 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
1891 APInt SubUndef = PoisonElts2.lshr(shiftAmt: OutIdx * Ratio).zextOrTrunc(width: Ratio);
1892 if (SubUndef.popcount() == Ratio)
1893 PoisonElts.setBit(OutIdx);
1894 }
1895 } else {
1896 llvm_unreachable("Unimp");
1897 }
1898 break;
1899 }
1900 case Instruction::FPTrunc:
1901 case Instruction::FPExt:
1902 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
1903 break;
1904
1905 case Instruction::Call: {
1906 IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I);
1907 if (!II) break;
1908 switch (II->getIntrinsicID()) {
1909 case Intrinsic::masked_gather: // fallthrough
1910 case Intrinsic::masked_load: {
1911 // Subtlety: If we load from a pointer, the pointer must be valid
1912 // regardless of whether the element is demanded. Doing otherwise risks
1913 // segfaults which didn't exist in the original program.
1914 APInt DemandedPtrs(APInt::getAllOnes(numBits: VWidth)),
1915 DemandedPassThrough(DemandedElts);
1916 if (auto *CMask = dyn_cast<Constant>(Val: II->getOperand(i_nocapture: 1))) {
1917 for (unsigned i = 0; i < VWidth; i++) {
1918 if (Constant *CElt = CMask->getAggregateElement(Elt: i)) {
1919 if (CElt->isNullValue())
1920 DemandedPtrs.clearBit(BitPosition: i);
1921 else if (CElt->isAllOnesValue())
1922 DemandedPassThrough.clearBit(BitPosition: i);
1923 }
1924 }
1925 }
1926
1927 if (II->getIntrinsicID() == Intrinsic::masked_gather)
1928 simplifyAndSetOp(II, 0, DemandedPtrs, PoisonElts2);
1929 simplifyAndSetOp(II, 2, DemandedPassThrough, PoisonElts3);
1930
1931 // Output elements are undefined if the element from both sources are.
1932 // TODO: can strengthen via mask as well.
1933 PoisonElts = PoisonElts2 & PoisonElts3;
1934 break;
1935 }
1936 default: {
1937 // Handle target specific intrinsics
1938 std::optional<Value *> V = targetSimplifyDemandedVectorEltsIntrinsic(
1939 II&: *II, DemandedElts, UndefElts&: PoisonElts, UndefElts2&: PoisonElts2, UndefElts3&: PoisonElts3,
1940 SimplifyAndSetOp: simplifyAndSetOp);
1941 if (V)
1942 return *V;
1943 break;
1944 }
1945 } // switch on IntrinsicID
1946 break;
1947 } // case Call
1948 } // switch on Opcode
1949
1950 // TODO: We bail completely on integer div/rem and shifts because they have
1951 // UB/poison potential, but that should be refined.
1952 BinaryOperator *BO;
1953 if (match(V: I, P: m_BinOp(I&: BO)) && !BO->isIntDivRem() && !BO->isShift()) {
1954 Value *X = BO->getOperand(i_nocapture: 0);
1955 Value *Y = BO->getOperand(i_nocapture: 1);
1956
1957 // Look for an equivalent binop except that one operand has been shuffled.
1958 // If the demand for this binop only includes elements that are the same as
1959 // the other binop, then we may be able to replace this binop with a use of
1960 // the earlier one.
1961 //
1962 // Example:
1963 // %other_bo = bo (shuf X, {0}), Y
1964 // %this_extracted_bo = extelt (bo X, Y), 0
1965 // -->
1966 // %other_bo = bo (shuf X, {0}), Y
1967 // %this_extracted_bo = extelt %other_bo, 0
1968 //
1969 // TODO: Handle demand of an arbitrary single element or more than one
1970 // element instead of just element 0.
1971 // TODO: Unlike general demanded elements transforms, this should be safe
1972 // for any (div/rem/shift) opcode too.
1973 if (DemandedElts == 1 && !X->hasOneUse() && !Y->hasOneUse() &&
1974 BO->hasOneUse() ) {
1975
1976 auto findShufBO = [&](bool MatchShufAsOp0) -> User * {
1977 // Try to use shuffle-of-operand in place of an operand:
1978 // bo X, Y --> bo (shuf X), Y
1979 // bo X, Y --> bo X, (shuf Y)
1980
1981 Value *OtherOp = MatchShufAsOp0 ? Y : X;
1982 if (!OtherOp->hasUseList())
1983 return nullptr;
1984
1985 BinaryOperator::BinaryOps Opcode = BO->getOpcode();
1986 Value *ShufOp = MatchShufAsOp0 ? X : Y;
1987
1988 for (User *U : OtherOp->users()) {
1989 ArrayRef<int> Mask;
1990 auto Shuf = m_Shuffle(v1: m_Specific(V: ShufOp), v2: m_Value(), mask: m_Mask(Mask));
1991 if (BO->isCommutative()
1992 ? match(V: U, P: m_c_BinOp(Opcode, L: Shuf, R: m_Specific(V: OtherOp)))
1993 : MatchShufAsOp0
1994 ? match(V: U, P: m_BinOp(Opcode, L: Shuf, R: m_Specific(V: OtherOp)))
1995 : match(V: U, P: m_BinOp(Opcode, L: m_Specific(V: OtherOp), R: Shuf)))
1996 if (match(Mask, P: m_ZeroMask()) && Mask[0] != PoisonMaskElem)
1997 if (DT.dominates(Def: U, User: I))
1998 return U;
1999 }
2000 return nullptr;
2001 };
2002
2003 if (User *ShufBO = findShufBO(/* MatchShufAsOp0 */ true))
2004 return ShufBO;
2005 if (User *ShufBO = findShufBO(/* MatchShufAsOp0 */ false))
2006 return ShufBO;
2007 }
2008
2009 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
2010 simplifyAndSetOp(I, 1, DemandedElts, PoisonElts2);
2011
2012 // Output elements are undefined if both are undefined. Consider things
2013 // like undef & 0. The result is known zero, not undef.
2014 PoisonElts &= PoisonElts2;
2015 }
2016
2017 // If we've proven all of the lanes poison, return a poison value.
2018 // TODO: Intersect w/demanded lanes
2019 if (PoisonElts.isAllOnes())
2020 return PoisonValue::get(T: I->getType());
2021
2022 return MadeChange ? I : nullptr;
2023}
2024
2025/// For floating-point classes that resolve to a single bit pattern, return that
2026/// value.
2027static Constant *getFPClassConstant(Type *Ty, FPClassTest Mask,
2028 bool IsCanonicalizing = false) {
2029 if (Mask == fcNone)
2030 return PoisonValue::get(T: Ty);
2031
2032 if (Mask == fcPosZero)
2033 return Constant::getNullValue(Ty);
2034
2035 // TODO: Support aggregate types that are allowed by FPMathOperator.
2036 if (Ty->isAggregateType())
2037 return nullptr;
2038
2039 // Turn any possible snans into quiet if we can.
2040 if (Mask == fcNan && IsCanonicalizing)
2041 return ConstantFP::getQNaN(Ty);
2042
2043 switch (Mask) {
2044 case fcNegZero:
2045 return ConstantFP::getZero(Ty, Negative: true);
2046 case fcPosInf:
2047 return ConstantFP::getInfinity(Ty);
2048 case fcNegInf:
2049 return ConstantFP::getInfinity(Ty, Negative: true);
2050 case fcQNan:
2051 // Payload bits cannot be dropped for pure signbit operations.
2052 return IsCanonicalizing ? ConstantFP::getQNaN(Ty) : nullptr;
2053 default:
2054 return nullptr;
2055 }
2056}
2057
2058/// Perform multiple-use aware simplfications for fabs(\p Src). Returns a
2059/// replacement value if it's simplified, otherwise nullptr. Updates \p Known
2060/// with the known fpclass if not simplified.
2061static Value *simplifyDemandedFPClassFabs(KnownFPClass &Known, Value *Src,
2062 FPClassTest DemandedMask,
2063 KnownFPClass KnownSrc, bool NSZ) {
2064 if ((DemandedMask & fcNan) == fcNone)
2065 KnownSrc.knownNot(RuleOut: fcNan);
2066 if ((DemandedMask & fcInf) == fcNone)
2067 KnownSrc.knownNot(RuleOut: fcInf);
2068
2069 if (KnownSrc.SignBit == false ||
2070 ((DemandedMask & fcNan) == fcNone && KnownSrc.isKnownNever(Mask: fcNegative)))
2071 return Src;
2072
2073 // If the only sign bit difference is due to -0, ignore it with nsz
2074 if (NSZ &&
2075 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedLessThanZeroMask | fcNan))
2076 return Src;
2077
2078 Known = KnownFPClass::fabs(Src: KnownSrc);
2079 Known.knownNot(RuleOut: ~DemandedMask);
2080 return nullptr;
2081}
2082
2083/// Try to set an inferred no-nans or no-infs in \p FMF. \p ValidResults is a
2084/// mask of known valid results for the operator (already computed from the
2085/// result, and the known operand inputs in \p Known)
2086static FastMathFlags inferFastMathValueFlags(FastMathFlags FMF,
2087 FPClassTest ValidResults,
2088 ArrayRef<KnownFPClass> Known) {
2089 if (!FMF.noNaNs() && (ValidResults & fcNan) == fcNone) {
2090 if (all_of(Range&: Known, P: [](const KnownFPClass KnownSrc) {
2091 return KnownSrc.isKnownNeverNaN();
2092 }))
2093 FMF.setNoNaNs();
2094 }
2095
2096 if (!FMF.noInfs() && (ValidResults & fcInf) == fcNone) {
2097 if (all_of(Range&: Known, P: [](const KnownFPClass KnownSrc) {
2098 return KnownSrc.isKnownNeverInfinity();
2099 }))
2100 FMF.setNoInfs();
2101 }
2102
2103 return FMF;
2104}
2105
2106static FPClassTest adjustDemandedMaskFromFlags(FPClassTest DemandedMask,
2107 FastMathFlags FMF) {
2108 if (FMF.noNaNs())
2109 DemandedMask &= ~fcNan;
2110
2111 if (FMF.noInfs())
2112 DemandedMask &= ~fcInf;
2113 return DemandedMask;
2114}
2115
2116/// Apply epilog fixups to a floating-point intrinsic. See if the result can
2117/// fold to a constant, or apply fast math flags.
2118static Value *simplifyDemandedFPClassResult(Instruction *FPOp,
2119 FastMathFlags FMF,
2120 FPClassTest DemandedMask,
2121 KnownFPClass &Known,
2122 ArrayRef<KnownFPClass> KnownSrcs) {
2123 FPClassTest ValidResults = DemandedMask & Known.KnownFPClasses;
2124 Constant *SingleVal = getFPClassConstant(Ty: FPOp->getType(), Mask: ValidResults,
2125 /*IsCanonicalizing=*/true);
2126 if (SingleVal)
2127 return SingleVal;
2128
2129 FastMathFlags InferredFMF =
2130 inferFastMathValueFlags(FMF, ValidResults, Known: KnownSrcs);
2131 if (InferredFMF != FMF) {
2132 FPOp->dropUBImplyingAttrsAndMetadata();
2133 FPOp->setFastMathFlags(InferredFMF);
2134 return FPOp;
2135 }
2136
2137 return nullptr;
2138}
2139
2140/// Perform multiple-use aware simplfications for fneg(fabs(\p Src)). Returns a
2141/// replacement value if it's simplified, otherwise nullptr. Updates \p Known
2142/// with the known fpclass if not simplified.
2143static Value *simplifyDemandedFPClassFnegFabs(KnownFPClass &Known, Value *Src,
2144 FPClassTest DemandedMask,
2145 KnownFPClass KnownSrc, bool NSZ) {
2146 if ((DemandedMask & fcNan) == fcNone)
2147 KnownSrc.knownNot(RuleOut: fcNan);
2148 if ((DemandedMask & fcInf) == fcNone)
2149 KnownSrc.knownNot(RuleOut: fcInf);
2150
2151 // If the source value is known negative, we can directly fold to it.
2152 if (KnownSrc.SignBit == true)
2153 return Src;
2154
2155 // If the only sign bit difference is for 0, ignore it with nsz.
2156 if (NSZ &&
2157 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedGreaterThanZeroMask | fcNan))
2158 return Src;
2159
2160 Known = KnownFPClass::fneg(Src: KnownFPClass::fabs(Src: KnownSrc));
2161 Known.knownNot(RuleOut: ~DemandedMask);
2162 return nullptr;
2163}
2164
2165static Value *simplifyDemandedFPClassCopysignMag(Value *MagSrc,
2166 FPClassTest DemandedMask,
2167 KnownFPClass KnownSrc,
2168 bool NSZ) {
2169 if (NSZ) {
2170 constexpr FPClassTest NegOrZero = fcNegative | fcPosZero;
2171 constexpr FPClassTest PosOrZero = fcPositive | fcNegZero;
2172
2173 if ((DemandedMask & ~NegOrZero) == fcNone &&
2174 KnownSrc.isKnownAlways(Mask: NegOrZero))
2175 return MagSrc;
2176
2177 if ((DemandedMask & ~PosOrZero) == fcNone &&
2178 KnownSrc.isKnownAlways(Mask: PosOrZero))
2179 return MagSrc;
2180 } else {
2181 if ((DemandedMask & ~fcNegative) == fcNone && KnownSrc.SignBit == true)
2182 return MagSrc;
2183
2184 if ((DemandedMask & ~fcPositive) == fcNone && KnownSrc.SignBit == false)
2185 return MagSrc;
2186 }
2187
2188 return nullptr;
2189}
2190
2191static Value *
2192simplifyDemandedFPClassMinMax(KnownFPClass &Known, Intrinsic::ID IID,
2193 const CallInst *CI, FPClassTest DemandedMask,
2194 KnownFPClass KnownLHS, KnownFPClass KnownRHS,
2195 const Function &F, bool NSZ) {
2196 bool OrderedZeroSign = !NSZ;
2197
2198 KnownFPClass::MinMaxKind OpKind;
2199 switch (IID) {
2200 case Intrinsic::maximum: {
2201 OpKind = KnownFPClass::MinMaxKind::maximum;
2202
2203 // If one operand is known greater than the other, it must be that
2204 // operand unless the other is a nan.
2205 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2206 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2207 KnownRHS.isKnownNever(Mask: fcNan))
2208 return CI->getArgOperand(i: 0);
2209
2210 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2211 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2212 KnownLHS.isKnownNever(Mask: fcNan))
2213 return CI->getArgOperand(i: 1);
2214
2215 break;
2216 }
2217 case Intrinsic::minimum: {
2218 OpKind = KnownFPClass::MinMaxKind::minimum;
2219
2220 // If one operand is known less than the other, it must be that operand
2221 // unless the other is a nan.
2222 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2223 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2224 KnownRHS.isKnownNever(Mask: fcNan))
2225 return CI->getArgOperand(i: 0);
2226
2227 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2228 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2229 KnownLHS.isKnownNever(Mask: fcNan))
2230 return CI->getArgOperand(i: 1);
2231
2232 break;
2233 }
2234 case Intrinsic::maxnum:
2235 case Intrinsic::maximumnum: {
2236 OpKind = IID == Intrinsic::maxnum ? KnownFPClass::MinMaxKind::maxnum
2237 : KnownFPClass::MinMaxKind::maximumnum;
2238
2239 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2240 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2241 KnownLHS.isKnownNever(Mask: fcNan))
2242 return CI->getArgOperand(i: 0);
2243
2244 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2245 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2246 KnownRHS.isKnownNever(Mask: fcNan))
2247 return CI->getArgOperand(i: 1);
2248
2249 break;
2250 }
2251 case Intrinsic::minnum:
2252 case Intrinsic::minimumnum: {
2253 OpKind = IID == Intrinsic::minnum ? KnownFPClass::MinMaxKind::minnum
2254 : KnownFPClass::MinMaxKind::minimumnum;
2255
2256 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2257 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2258 KnownLHS.isKnownNever(Mask: fcNan))
2259 return CI->getArgOperand(i: 0);
2260
2261 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2262 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2263 KnownRHS.isKnownNever(Mask: fcNan))
2264 return CI->getArgOperand(i: 1);
2265
2266 break;
2267 }
2268 default:
2269 llvm_unreachable("not a min/max intrinsic");
2270 }
2271
2272 Type *EltTy = CI->getType()->getScalarType();
2273 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2274 Known = KnownFPClass::minMaxLike(LHS: KnownLHS, RHS: KnownRHS, Kind: OpKind, DenormMode: Mode);
2275 Known.knownNot(RuleOut: ~DemandedMask);
2276
2277 return getFPClassConstant(Ty: CI->getType(), Mask: Known.KnownFPClasses,
2278 /*IsCanonicalizing=*/true);
2279}
2280
2281static Value *
2282simplifyDemandedUseFPClassFPTrunc(InstCombinerImpl &IC, Instruction &I,
2283 FastMathFlags FMF, FPClassTest DemandedMask,
2284 KnownFPClass &Known, unsigned Depth) {
2285
2286 FPClassTest SrcDemandedMask = DemandedMask;
2287 if (DemandedMask & fcNan)
2288 SrcDemandedMask |= fcNan;
2289
2290 // Zero results may have been rounded from subnormal or normal sources.
2291 if (DemandedMask & fcNegZero)
2292 SrcDemandedMask |= fcNegSubnormal | fcNegNormal;
2293 if (DemandedMask & fcPosZero)
2294 SrcDemandedMask |= fcPosSubnormal | fcPosNormal;
2295
2296 // Subnormal results may have been normal in the source type
2297 if (DemandedMask & fcNegSubnormal)
2298 SrcDemandedMask |= fcNegNormal;
2299 if (DemandedMask & fcPosSubnormal)
2300 SrcDemandedMask |= fcPosNormal;
2301
2302 if (DemandedMask & fcPosInf)
2303 SrcDemandedMask |= fcPosNormal;
2304 if (DemandedMask & fcNegInf)
2305 SrcDemandedMask |= fcNegNormal;
2306
2307 KnownFPClass KnownSrc;
2308 if (IC.SimplifyDemandedFPClass(I: &I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Depth: Depth + 1))
2309 return &I;
2310
2311 Known = KnownFPClass::fptrunc(KnownSrc);
2312 Known.knownNot(RuleOut: ~DemandedMask);
2313
2314 return simplifyDemandedFPClassResult(FPOp: &I, FMF, DemandedMask, Known,
2315 KnownSrcs: {KnownSrc});
2316}
2317
2318Value *InstCombinerImpl::SimplifyDemandedUseFPClass(Instruction *I,
2319 FPClassTest DemandedMask,
2320 KnownFPClass &Known,
2321 Instruction *CxtI,
2322 unsigned Depth) {
2323 assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
2324 assert(Known == KnownFPClass() && "expected uninitialized state");
2325
2326 Type *VTy = I->getType();
2327
2328 FastMathFlags FMF;
2329 if (auto *FPOp = dyn_cast<FPMathOperator>(Val: I)) {
2330 FMF = FPOp->getFastMathFlags();
2331 DemandedMask = adjustDemandedMaskFromFlags(DemandedMask, FMF);
2332 }
2333
2334 switch (I->getOpcode()) {
2335 case Instruction::FNeg: {
2336 // Special case fneg(fabs(x))
2337
2338 Value *FNegSrc = I->getOperand(i: 0);
2339 Value *FNegFAbsSrc;
2340 if (match(V: FNegSrc, P: m_OneUse(SubPattern: m_FAbs(Op0: m_Value(V&: FNegFAbsSrc))))) {
2341 KnownFPClass KnownSrc;
2342 if (SimplifyDemandedFPClass(I: cast<Instruction>(Val: FNegSrc), Op: 0,
2343 DemandedMask: llvm::unknown_sign(Mask: DemandedMask), Known&: KnownSrc,
2344 Depth: Depth + 1))
2345 return I;
2346
2347 FastMathFlags FabsFMF = cast<FPMathOperator>(Val: FNegSrc)->getFastMathFlags();
2348 FPClassTest ThisDemandedMask =
2349 adjustDemandedMaskFromFlags(DemandedMask, FMF: FabsFMF);
2350
2351 bool IsNSZ = FMF.noSignedZeros() || FabsFMF.noSignedZeros();
2352 if (Value *Simplified = simplifyDemandedFPClassFnegFabs(
2353 Known, Src: FNegFAbsSrc, DemandedMask: ThisDemandedMask, KnownSrc, NSZ: IsNSZ))
2354 return Simplified;
2355
2356 if ((ThisDemandedMask & fcNan) == fcNone)
2357 KnownSrc.knownNot(RuleOut: fcNan);
2358 if ((ThisDemandedMask & fcInf) == fcNone)
2359 KnownSrc.knownNot(RuleOut: fcInf);
2360
2361 // fneg(fabs(x)) => fneg(x)
2362 if (KnownSrc.SignBit == false)
2363 return replaceOperand(I&: *I, OpNum: 0, V: FNegFAbsSrc);
2364
2365 // fneg(fabs(x)) => fneg(x), ignoring -0 if nsz.
2366 if (IsNSZ &&
2367 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedLessThanZeroMask | fcNan))
2368 return replaceOperand(I&: *I, OpNum: 0, V: FNegFAbsSrc);
2369
2370 break;
2371 }
2372
2373 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: llvm::fneg(Mask: DemandedMask), Known,
2374 Depth: Depth + 1))
2375 return I;
2376 Known.fneg();
2377 Known.knownNot(RuleOut: ~DemandedMask);
2378 break;
2379 }
2380 case Instruction::FAdd:
2381 case Instruction::FSub: {
2382 KnownFPClass KnownLHS, KnownRHS;
2383
2384 // fadd x, x can be handled more aggressively.
2385 if (I->getOperand(i: 0) == I->getOperand(i: 1) &&
2386 I->getOpcode() == Instruction::FAdd &&
2387 isGuaranteedNotToBeUndef(V: I->getOperand(i: 0), AC: SQ.AC, CtxI: CxtI, DT: SQ.DT,
2388 Depth: Depth + 1)) {
2389 Type *EltTy = VTy->getScalarType();
2390 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2391
2392 FPClassTest SrcDemandedMask = DemandedMask;
2393 if (DemandedMask & fcNan)
2394 SrcDemandedMask |= fcNan;
2395
2396 // Doubling a subnormal could have resulted in a normal value.
2397 if (DemandedMask & fcPosNormal)
2398 SrcDemandedMask |= fcPosSubnormal;
2399 if (DemandedMask & fcNegNormal)
2400 SrcDemandedMask |= fcNegSubnormal;
2401
2402 // Doubling a subnormal may produce 0 if FTZ/DAZ.
2403 if (Mode != DenormalMode::getIEEE()) {
2404 if (DemandedMask & fcPosZero) {
2405 SrcDemandedMask |= fcPosSubnormal;
2406
2407 if (Mode.inputsMayBePositiveZero() || Mode.outputsMayBePositiveZero())
2408 SrcDemandedMask |= fcNegSubnormal;
2409 }
2410
2411 if (DemandedMask & fcNegZero)
2412 SrcDemandedMask |= fcNegSubnormal;
2413 }
2414
2415 // Doubling a normal could have resulted in an infinity.
2416 if (DemandedMask & fcPosInf)
2417 SrcDemandedMask |= fcPosNormal;
2418 if (DemandedMask & fcNegInf)
2419 SrcDemandedMask |= fcNegNormal;
2420
2421 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Depth: Depth + 1))
2422 return I;
2423
2424 Known = KnownFPClass::fadd_self(Src: KnownLHS, Mode);
2425 KnownRHS = KnownLHS;
2426 } else {
2427 FPClassTest SrcDemandedMask = fcFinite;
2428
2429 // inf + (-inf) = nan
2430 if (DemandedMask & fcNan)
2431 SrcDemandedMask |= fcNan | fcInf;
2432
2433 if (DemandedMask & fcInf)
2434 SrcDemandedMask |= fcInf;
2435
2436 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS, Depth: Depth + 1) ||
2437 SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Depth: Depth + 1))
2438 return I;
2439
2440 Type *EltTy = VTy->getScalarType();
2441 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2442
2443 Known = I->getOpcode() == Instruction::FAdd
2444 ? KnownFPClass::fadd(LHS: KnownLHS, RHS: KnownRHS, Mode)
2445 : KnownFPClass::fsub(LHS: KnownLHS, RHS: KnownRHS, Mode);
2446 }
2447
2448 Known.knownNot(RuleOut: ~DemandedMask);
2449
2450 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2451 /*IsCanonicalizing=*/true))
2452 return SingleVal;
2453
2454 // Propagate known result to simplify edge case checks.
2455 bool ResultNotNan = (DemandedMask & fcNan) == fcNone;
2456
2457 // With nnan: X + {+/-}Inf --> {+/-}Inf
2458 if (ResultNotNan && I->getOpcode() == Instruction::FAdd &&
2459 KnownRHS.isKnownAlways(Mask: fcInf | fcNan) && KnownLHS.isKnownNever(Mask: fcNan))
2460 return I->getOperand(i: 1);
2461
2462 // With nnan: {+/-}Inf + X --> {+/-}Inf
2463 // With nnan: {+/-}Inf - X --> {+/-}Inf
2464 if (ResultNotNan && KnownLHS.isKnownAlways(Mask: fcInf | fcNan) &&
2465 KnownRHS.isKnownNever(Mask: fcNan))
2466 return I->getOperand(i: 0);
2467
2468 FastMathFlags InferredFMF = inferFastMathValueFlags(
2469 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2470 if (InferredFMF != FMF) {
2471 I->setFastMathFlags(InferredFMF);
2472 return I;
2473 }
2474
2475 return nullptr;
2476 }
2477 case Instruction::FMul: {
2478 KnownFPClass KnownLHS, KnownRHS;
2479
2480 Value *X = I->getOperand(i: 0);
2481 Value *Y = I->getOperand(i: 1);
2482
2483 FPClassTest SrcDemandedMask =
2484 DemandedMask & (fcNan | fcZero | fcSubnormal | fcNormal);
2485
2486 if (DemandedMask & fcInf) {
2487 // mul x, inf = inf
2488 // mul large_x, large_y = inf
2489 SrcDemandedMask |= fcSubnormal | fcNormal | fcInf;
2490 }
2491
2492 if (DemandedMask & fcNan) {
2493 // mul +/-inf, 0 => nan
2494 SrcDemandedMask |= fcZero | fcInf | fcNan;
2495
2496 // TODO: Mode check
2497 // mul +/-inf, sub => nan if daz
2498 SrcDemandedMask |= fcSubnormal;
2499 }
2500
2501 // mul normal, subnormal = normal
2502 // Normal inputs may result in underflow.
2503 if (DemandedMask & (fcNormal | fcSubnormal))
2504 SrcDemandedMask |= fcNormal | fcSubnormal;
2505
2506 if (DemandedMask & fcZero)
2507 SrcDemandedMask |= fcNormal | fcSubnormal;
2508
2509 if (X == Y && isGuaranteedNotToBeUndef(V: X, AC: SQ.AC, CtxI: CxtI, DT: SQ.DT, Depth: Depth + 1)) {
2510 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Depth: Depth + 1))
2511 return I;
2512 Type *EltTy = VTy->getScalarType();
2513
2514 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2515 Known = KnownFPClass::square(Src: KnownLHS, Mode);
2516 Known.knownNot(RuleOut: ~DemandedMask);
2517
2518 if (Constant *Folded = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2519 /*IsCanonicalizing=*/true))
2520 return Folded;
2521
2522 if (Known.isKnownAlways(Mask: fcPosZero | fcPosInf | fcNan) &&
2523 KnownLHS.isKnownNever(Mask: fcSubnormal | fcNormal)) {
2524 // We can skip the fabs if the source was already known positive.
2525 if (KnownLHS.isKnownAlways(Mask: fcPositive))
2526 return X;
2527
2528 // => fabs(x), in case this was a -inf or -0.
2529 // Note: Dropping canonicalize.
2530 IRBuilderBase::InsertPointGuard Guard(Builder);
2531 Builder.SetInsertPoint(I);
2532 Value *Fabs = Builder.CreateUnaryIntrinsic(ID: Intrinsic::fabs, V: X, FMFSource: FMF);
2533 Fabs->takeName(V: I);
2534 return Fabs;
2535 }
2536
2537 return nullptr;
2538 }
2539
2540 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS, Depth: Depth + 1) ||
2541 SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Depth: Depth + 1))
2542 return I;
2543
2544 if (FMF.noInfs()) {
2545 // Flag implies inputs cannot be infinity.
2546 KnownLHS.knownNot(RuleOut: fcInf);
2547 KnownRHS.knownNot(RuleOut: fcInf);
2548 }
2549
2550 bool NonNanResult = (DemandedMask & fcNan) == fcNone;
2551
2552 // With no-nans/no-infs:
2553 // X * 0.0 --> copysign(0.0, X)
2554 // X * -0.0 --> copysign(0.0, -X)
2555 if ((NonNanResult || KnownLHS.isKnownNeverInfOrNaN()) &&
2556 KnownRHS.isKnownAlways(Mask: fcPosZero | fcNan)) {
2557 IRBuilderBase::InsertPointGuard Guard(Builder);
2558 Builder.SetInsertPoint(I);
2559
2560 // => copysign(+0, lhs)
2561 // Note: Dropping canonicalize
2562 Value *Copysign = Builder.CreateCopySign(LHS: Y, RHS: X, FMFSource: FMF);
2563 Copysign->takeName(V: I);
2564 return Copysign;
2565 }
2566
2567 if (KnownLHS.isKnownAlways(Mask: fcPosZero | fcNan) &&
2568 (NonNanResult || KnownRHS.isKnownNeverInfOrNaN())) {
2569 IRBuilderBase::InsertPointGuard Guard(Builder);
2570 Builder.SetInsertPoint(I);
2571
2572 // => copysign(+0, rhs)
2573 // Note: Dropping canonicalize
2574 Value *Copysign = Builder.CreateCopySign(LHS: X, RHS: Y, FMFSource: FMF);
2575 Copysign->takeName(V: I);
2576 return Copysign;
2577 }
2578
2579 if ((NonNanResult || KnownLHS.isKnownNeverInfOrNaN()) &&
2580 KnownRHS.isKnownAlways(Mask: fcNegZero | fcNan)) {
2581 IRBuilderBase::InsertPointGuard Guard(Builder);
2582 Builder.SetInsertPoint(I);
2583
2584 // => copysign(0, fneg(lhs))
2585 // Note: Dropping canonicalize
2586 Value *Copysign =
2587 Builder.CreateCopySign(LHS: Y, RHS: Builder.CreateFNegFMF(V: X, FMFSource: FMF), FMFSource: FMF);
2588 Copysign->takeName(V: I);
2589 return Copysign;
2590 }
2591
2592 if (KnownLHS.isKnownAlways(Mask: fcNegZero | fcNan) &&
2593 (NonNanResult || KnownRHS.isKnownNeverInfOrNaN())) {
2594 IRBuilderBase::InsertPointGuard Guard(Builder);
2595 Builder.SetInsertPoint(I);
2596
2597 // => copysign(+0, fneg(rhs))
2598 // Note: Dropping canonicalize
2599 Value *Copysign =
2600 Builder.CreateCopySign(LHS: X, RHS: Builder.CreateFNegFMF(V: Y, FMFSource: FMF), FMFSource: FMF);
2601 Copysign->takeName(V: I);
2602 return Copysign;
2603 }
2604
2605 Type *EltTy = VTy->getScalarType();
2606 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2607
2608 if (KnownLHS.isKnownAlways(Mask: fcInf | fcNan) &&
2609 (KnownRHS.isKnownNeverNaN() &&
2610 KnownRHS.cannotBeOrderedGreaterEqZero(Mode))) {
2611 IRBuilderBase::InsertPointGuard Guard(Builder);
2612 Builder.SetInsertPoint(I);
2613
2614 // Note: Dropping canonicalize
2615 Value *Neg = Builder.CreateFNegFMF(V: X, FMFSource: FMF);
2616 Neg->takeName(V: I);
2617 return Neg;
2618 }
2619
2620 if (KnownRHS.isKnownAlways(Mask: fcInf | fcNan) &&
2621 (KnownLHS.isKnownNeverNaN() &&
2622 KnownLHS.cannotBeOrderedGreaterEqZero(Mode))) {
2623 IRBuilderBase::InsertPointGuard Guard(Builder);
2624 Builder.SetInsertPoint(I);
2625
2626 // Note: Dropping canonicalize
2627 Value *Neg = Builder.CreateFNegFMF(V: Y, FMFSource: FMF);
2628 Neg->takeName(V: I);
2629 return Neg;
2630 }
2631
2632 Known = KnownFPClass::fmul(LHS: KnownLHS, RHS: KnownRHS, Mode);
2633 Known.knownNot(RuleOut: ~DemandedMask);
2634
2635 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2636 /*IsCanonicalizing=*/true))
2637 return SingleVal;
2638
2639 FastMathFlags InferredFMF = inferFastMathValueFlags(
2640 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2641 if (InferredFMF != FMF) {
2642 I->setFastMathFlags(InferredFMF);
2643 return I;
2644 }
2645
2646 return nullptr;
2647 }
2648 case Instruction::FDiv: {
2649 Value *X = I->getOperand(i: 0);
2650 Value *Y = I->getOperand(i: 1);
2651 if (X == Y && isGuaranteedNotToBeUndef(V: X, AC: SQ.AC, CtxI: CxtI, DT: SQ.DT, Depth: Depth + 1)) {
2652 // If the source is 0, inf or nan, the result is a nan
2653 IRBuilderBase::InsertPointGuard Guard(Builder);
2654 Builder.SetInsertPoint(I);
2655
2656 Value *IsZeroOrNan = Builder.CreateFCmpFMF(
2657 P: FCmpInst::FCMP_UEQ, LHS: I->getOperand(i: 0), RHS: ConstantFP::getZero(Ty: VTy), FMFSource: FMF);
2658
2659 Value *Fabs =
2660 Builder.CreateUnaryIntrinsic(ID: Intrinsic::fabs, V: I->getOperand(i: 0), FMFSource: FMF);
2661 Value *IsInfOrNan = Builder.CreateFCmpFMF(
2662 P: FCmpInst::FCMP_UEQ, LHS: Fabs, RHS: ConstantFP::getInfinity(Ty: VTy), FMFSource: FMF);
2663
2664 Value *IsInfOrZeroOrNan = Builder.CreateOr(LHS: IsInfOrNan, RHS: IsZeroOrNan);
2665
2666 return Builder.CreateSelectFMFWithUnknownProfile(
2667 C: IsInfOrZeroOrNan, True: ConstantFP::getQNaN(Ty: VTy),
2668 False: ConstantFP::get(
2669 Ty: VTy, V: APFloat::getOne(Sem: VTy->getScalarType()->getFltSemantics())),
2670 FMFSource: FMF, DEBUG_TYPE);
2671 }
2672
2673 Type *EltTy = VTy->getScalarType();
2674 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2675
2676 // Every output class could require denormal inputs (except for the
2677 // degenerate case of only-nan results, without DAZ).
2678 FPClassTest SrcDemandedMask = (DemandedMask & fcNan) | fcSubnormal;
2679
2680 // Normal inputs may result in underflow.
2681 // x / x = 1.0 for non0/inf/nan
2682 // -x = +y / -z
2683 // -x = -y / +z
2684 if (DemandedMask & (fcSubnormal | fcNormal))
2685 SrcDemandedMask |= fcNormal;
2686
2687 if (DemandedMask & fcNan) {
2688 // 0 / 0 = nan
2689 // inf / inf = nan
2690
2691 // Subnormal is added in case of DAZ, but this isn't strictly
2692 // necessary. Every other input class implies a possible subnormal source,
2693 // so this only could matter in the degenerate case of only-nan results.
2694 SrcDemandedMask |= fcZero | fcInf | fcNan;
2695 }
2696
2697 // Zero outputs may be the result of underflow.
2698 if (DemandedMask & fcZero)
2699 SrcDemandedMask |= fcNormal | fcSubnormal;
2700
2701 FPClassTest LHSDemandedMask = SrcDemandedMask;
2702 FPClassTest RHSDemandedMask = SrcDemandedMask;
2703
2704 // 0 / inf = 0
2705 if (DemandedMask & fcZero) {
2706 assert((LHSDemandedMask & fcSubnormal) &&
2707 "should not have to worry about daz here");
2708 LHSDemandedMask |= fcZero;
2709 RHSDemandedMask |= fcInf;
2710 }
2711
2712 // x / 0 = inf
2713 // large_normal / small_normal = inf
2714 // inf / 1 = inf
2715 // large_normal / subnormal = inf
2716 if (DemandedMask & fcInf) {
2717 LHSDemandedMask |= fcInf | fcNormal | fcSubnormal;
2718 RHSDemandedMask |= fcZero | fcSubnormal | fcNormal;
2719 }
2720
2721 KnownFPClass KnownLHS, KnownRHS;
2722 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: LHSDemandedMask, Known&: KnownLHS, Depth: Depth + 1) ||
2723 SimplifyDemandedFPClass(I, Op: 1, DemandedMask: RHSDemandedMask, Known&: KnownRHS, Depth: Depth + 1))
2724 return I;
2725
2726 // nsz [+-]0 / x -> 0
2727 if (FMF.noSignedZeros() && KnownLHS.isKnownAlways(Mask: fcZero) &&
2728 KnownRHS.isKnownNeverNaN())
2729 return ConstantFP::getZero(Ty: VTy);
2730
2731 if (KnownLHS.isKnownAlways(Mask: fcPosZero) && KnownRHS.isKnownNeverNaN()) {
2732 IRBuilderBase::InsertPointGuard Guard(Builder);
2733 Builder.SetInsertPoint(I);
2734
2735 // nnan +0 / x -> copysign(0, rhs)
2736 // TODO: -0 / x => copysign(0, fneg(rhs))
2737 Value *Copysign = Builder.CreateCopySign(LHS: X, RHS: Y, FMFSource: FMF);
2738 Copysign->takeName(V: I);
2739 return Copysign;
2740 }
2741
2742 bool ResultNotNan = (DemandedMask & fcNan) == fcNone;
2743 bool ResultNotInf = (DemandedMask & fcInf) == fcNone;
2744
2745 if (!ResultNotInf &&
2746 ((ResultNotNan || (KnownLHS.isKnownNeverNaN() &&
2747 KnownLHS.isKnownNeverLogicalZero(Mode))) &&
2748 (KnownRHS.isKnownAlways(Mask: fcPosZero) ||
2749 (FMF.noSignedZeros() && KnownRHS.isKnownAlways(Mask: fcZero))))) {
2750 IRBuilderBase::InsertPointGuard Guard(Builder);
2751 Builder.SetInsertPoint(I);
2752
2753 // nnan x / 0 => copysign(inf, x);
2754 // nnan nsz x / -0 => copysign(inf, x);
2755 Value *Copysign =
2756 Builder.CreateCopySign(LHS: ConstantFP::getInfinity(Ty: VTy), RHS: X, FMFSource: FMF);
2757 Copysign->takeName(V: I);
2758 return Copysign;
2759 }
2760
2761 // nnan ninf X / [-]0.0 -> poison
2762 if (ResultNotNan && ResultNotInf && KnownRHS.isKnownAlways(Mask: fcZero))
2763 return PoisonValue::get(T: VTy);
2764
2765 Known = KnownFPClass::fdiv(LHS: KnownLHS, RHS: KnownRHS, Mode);
2766 Known.knownNot(RuleOut: ~DemandedMask);
2767
2768 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2769 /*IsCanonicalizing=*/true))
2770 return SingleVal;
2771
2772 FastMathFlags InferredFMF = inferFastMathValueFlags(
2773 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2774 if (InferredFMF != FMF) {
2775 I->setFastMathFlags(InferredFMF);
2776 return I;
2777 }
2778
2779 return nullptr;
2780 }
2781 case Instruction::FPTrunc:
2782 return simplifyDemandedUseFPClassFPTrunc(IC&: *this, I&: *I, FMF, DemandedMask,
2783 Known, Depth);
2784 case Instruction::FPExt: {
2785 FPClassTest SrcDemandedMask = DemandedMask;
2786 if (DemandedMask & fcNan)
2787 SrcDemandedMask |= fcNan;
2788
2789 // No subnormal result does not imply not-subnormal in the source type.
2790 if ((DemandedMask & fcNegNormal) != fcNone)
2791 SrcDemandedMask |= fcNegSubnormal;
2792 if ((DemandedMask & fcPosNormal) != fcNone)
2793 SrcDemandedMask |= fcPosSubnormal;
2794
2795 KnownFPClass KnownSrc;
2796 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Depth: Depth + 1))
2797 return I;
2798
2799 const fltSemantics &DstTy = VTy->getScalarType()->getFltSemantics();
2800 const fltSemantics &SrcTy =
2801 I->getOperand(i: 0)->getType()->getScalarType()->getFltSemantics();
2802
2803 Known = KnownFPClass::fpext(KnownSrc, DstTy, SrcTy);
2804 Known.knownNot(RuleOut: ~DemandedMask);
2805
2806 return simplifyDemandedFPClassResult(FPOp: I, FMF, DemandedMask, Known,
2807 KnownSrcs: {KnownSrc});
2808 }
2809 case Instruction::Call: {
2810 CallInst *CI = cast<CallInst>(Val: I);
2811 const Intrinsic::ID IID = CI->getIntrinsicID();
2812 switch (IID) {
2813 case Intrinsic::fabs: {
2814 KnownFPClass KnownSrc;
2815 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: llvm::inverse_fabs(Mask: DemandedMask),
2816 Known&: KnownSrc, Depth: Depth + 1))
2817 return I;
2818
2819 if (Value *Simplified = simplifyDemandedFPClassFabs(
2820 Known, Src: CI->getArgOperand(i: 0), DemandedMask, KnownSrc,
2821 NSZ: FMF.noSignedZeros()))
2822 return Simplified;
2823 break;
2824 }
2825 case Intrinsic::arithmetic_fence:
2826 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known, Depth: Depth + 1))
2827 return I;
2828 break;
2829 case Intrinsic::copysign: {
2830 // Flip on more potentially demanded classes
2831 const FPClassTest DemandedMaskAnySign = llvm::unknown_sign(Mask: DemandedMask);
2832 KnownFPClass KnownMag;
2833 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: DemandedMaskAnySign, Known&: KnownMag,
2834 Depth: Depth + 1))
2835 return I;
2836
2837 if ((DemandedMask & fcNegative) == DemandedMask) {
2838 // Roundabout way of replacing with fneg(fabs)
2839 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::get(Ty: VTy, V: -1.0));
2840 return I;
2841 }
2842
2843 if ((DemandedMask & fcPositive) == DemandedMask) {
2844 // Roundabout way of replacing with fabs
2845 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::getZero(Ty: VTy));
2846 return I;
2847 }
2848
2849 if (Value *Simplified = simplifyDemandedFPClassCopysignMag(
2850 MagSrc: CI->getArgOperand(i: 0), DemandedMask, KnownSrc: KnownMag,
2851 NSZ: FMF.noSignedZeros()))
2852 return Simplified;
2853
2854 KnownFPClass KnownSign = computeKnownFPClass(Val: CI->getArgOperand(i: 1),
2855 Interested: fcAllFlags, CtxI: CxtI, Depth: Depth + 1);
2856 if (KnownMag.SignBit && KnownSign.SignBit &&
2857 *KnownMag.SignBit == *KnownSign.SignBit)
2858 return CI->getOperand(i_nocapture: 0);
2859
2860 // TODO: Call argument attribute not considered
2861 // Input implied not-nan from flag.
2862 if (FMF.noNaNs())
2863 KnownSign.knownNot(RuleOut: fcNan);
2864
2865 if (KnownSign.SignBit == false) {
2866 CI->dropUBImplyingAttrsAndMetadata();
2867 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::getZero(Ty: VTy));
2868 return I;
2869 }
2870
2871 if (KnownSign.SignBit == true) {
2872 CI->dropUBImplyingAttrsAndMetadata();
2873 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::get(Ty: VTy, V: -1.0));
2874 return I;
2875 }
2876
2877 Known = KnownFPClass::copysign(KnownMag, KnownSign);
2878 Known.knownNot(RuleOut: ~DemandedMask);
2879 break;
2880 }
2881 case Intrinsic::fma:
2882 case Intrinsic::fmuladd: {
2883 // We can't do any simplification on the source besides stripping out
2884 // unneeded nans.
2885 FPClassTest SrcDemandedMask = DemandedMask | ~fcNan;
2886 if (DemandedMask & fcNan)
2887 SrcDemandedMask |= fcNan;
2888
2889 KnownFPClass KnownSrc[3];
2890
2891 Type *EltTy = VTy->getScalarType();
2892 if (CI->getArgOperand(i: 0) == CI->getArgOperand(i: 1) &&
2893 isGuaranteedNotToBeUndef(V: CI->getArgOperand(i: 0), AC: SQ.AC, CtxI: CxtI, DT: SQ.DT,
2894 Depth: Depth + 1)) {
2895 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc[0],
2896 Depth: Depth + 1) ||
2897 SimplifyDemandedFPClass(I: CI, Op: 2, DemandedMask: SrcDemandedMask, Known&: KnownSrc[2],
2898 Depth: Depth + 1))
2899 return I;
2900
2901 KnownSrc[1] = KnownSrc[0];
2902 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2903 Known = KnownFPClass::fma_square(Squared: KnownSrc[0], Addend: KnownSrc[2], Mode);
2904 } else {
2905 for (int OpIdx = 0; OpIdx != 3; ++OpIdx) {
2906 if (SimplifyDemandedFPClass(I: CI, Op: OpIdx, DemandedMask: SrcDemandedMask,
2907 Known&: KnownSrc[OpIdx], Depth: Depth + 1))
2908 return CI;
2909 }
2910
2911 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2912 Known = KnownFPClass::fma(LHS: KnownSrc[0], RHS: KnownSrc[1], Addend: KnownSrc[2], Mode);
2913 }
2914
2915 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
2916 KnownSrcs: {KnownSrc});
2917 }
2918 case Intrinsic::maximum:
2919 case Intrinsic::minimum:
2920 case Intrinsic::maximumnum:
2921 case Intrinsic::minimumnum:
2922 case Intrinsic::maxnum:
2923 case Intrinsic::minnum: {
2924 const bool PropagateNaN =
2925 IID == Intrinsic::maximum || IID == Intrinsic::minimum;
2926
2927 // We can't tell much based on the demanded result without inspecting the
2928 // operands (e.g., a known-positive result could have been clamped), but
2929 // we can still prune known-nan inputs.
2930 FPClassTest SrcDemandedMask =
2931 PropagateNaN && ((DemandedMask & fcNan) == fcNone)
2932 ? DemandedMask | ~fcNan
2933 : fcAllFlags;
2934
2935 KnownFPClass KnownLHS, KnownRHS;
2936 if (SimplifyDemandedFPClass(I: CI, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS,
2937 Depth: Depth + 1) ||
2938 SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Depth: Depth + 1))
2939 return I;
2940
2941 Value *Simplified =
2942 simplifyDemandedFPClassMinMax(Known, IID, CI, DemandedMask, KnownLHS,
2943 KnownRHS, F, NSZ: FMF.noSignedZeros());
2944 if (Simplified)
2945 return Simplified;
2946
2947 auto *FPOp = cast<FPMathOperator>(Val: CI);
2948
2949 FPClassTest ValidResults = DemandedMask & Known.KnownFPClasses;
2950 FastMathFlags InferredFMF = FMF;
2951
2952 if (!FMF.noSignedZeros()) {
2953 // Add NSZ flag if we know the result will not be sensitive to the sign
2954 // of 0.
2955 FPClassTest ZeroMask = fcZero;
2956
2957 Type *EltTy = VTy->getScalarType();
2958 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2959 if (Mode != DenormalMode::getIEEE())
2960 ZeroMask |= fcSubnormal;
2961
2962 bool ResultNotLogical0 = (ValidResults & ZeroMask) == fcNone;
2963 if (ResultNotLogical0 || ((KnownLHS.isKnownNeverLogicalNegZero(Mode) ||
2964 KnownRHS.isKnownNeverLogicalPosZero(Mode)) &&
2965 (KnownLHS.isKnownNeverLogicalPosZero(Mode) ||
2966 KnownRHS.isKnownNeverLogicalNegZero(Mode))))
2967 InferredFMF.setNoSignedZeros(true);
2968 }
2969
2970 if (!FMF.noNaNs() &&
2971 ((PropagateNaN && (ValidResults & fcNan) == fcNone) ||
2972 (KnownLHS.isKnownNeverNaN() && KnownRHS.isKnownNeverNaN()))) {
2973 CI->dropUBImplyingAttrsAndMetadata();
2974 InferredFMF.setNoNaNs(true);
2975 }
2976
2977 if (InferredFMF != FMF) {
2978 CI->setFastMathFlags(InferredFMF);
2979 return FPOp;
2980 }
2981
2982 return nullptr;
2983 }
2984 case Intrinsic::exp:
2985 case Intrinsic::exp2:
2986 case Intrinsic::exp10: {
2987 if ((DemandedMask & fcPositive) == fcNone) {
2988 // Only returns positive values or nans.
2989 if ((DemandedMask & fcNan) == fcNone)
2990 return PoisonValue::get(T: VTy);
2991
2992 // Only need nan propagation.
2993 if ((DemandedMask & ~fcNan) == fcNone)
2994 return ConstantFP::getQNaN(Ty: VTy);
2995
2996 return CI->getArgOperand(i: 0);
2997 }
2998
2999 FPClassTest SrcDemandedMask = DemandedMask & fcNan;
3000 if (DemandedMask & fcNan)
3001 SrcDemandedMask |= fcNan;
3002
3003 if (DemandedMask & fcZero) {
3004 // exp(-infinity) = 0
3005 SrcDemandedMask |= fcNegInf;
3006
3007 // exp(-largest_normal) = 0
3008 //
3009 // Negative numbers of sufficiently large magnitude underflow to 0. No
3010 // subnormal input has a 0 result.
3011 SrcDemandedMask |= fcNegNormal;
3012 }
3013
3014 if (DemandedMask & fcPosSubnormal) {
3015 // Negative numbers of sufficiently large magnitude underflow to 0. No
3016 // subnormal input has a 0 result.
3017 SrcDemandedMask |= fcNegNormal;
3018 }
3019
3020 if (DemandedMask & fcPosNormal) {
3021 // exp(0) = 1
3022 // exp(+/- smallest_normal) = 1
3023 // exp(+/- largest_denormal) = 1
3024 // exp(+/- smallest_denormal) = 1
3025 // exp(-1) = pos normal
3026 SrcDemandedMask |= fcNormal | fcSubnormal | fcZero;
3027 }
3028
3029 // exp(inf), exp(largest_normal) = inf
3030 if (DemandedMask & fcPosInf)
3031 SrcDemandedMask |= fcPosInf | fcPosNormal;
3032
3033 KnownFPClass KnownSrc;
3034
3035 // TODO: This could really make use of KnownFPClass of specific value
3036 // range, (i.e., close enough to 1)
3037 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Depth: Depth + 1))
3038 return I;
3039
3040 // exp(+/-0) = 1
3041 if (KnownSrc.isKnownAlways(Mask: fcZero))
3042 return ConstantFP::get(Ty: VTy, V: 1.0);
3043
3044 // Only perform nan propagation.
3045 // Note: Dropping canonicalize / quiet of signaling nan.
3046 if (KnownSrc.isKnownAlways(Mask: fcNan))
3047 return CI->getArgOperand(i: 0);
3048
3049 // exp(0 | nan) => x == 0.0 ? 1.0 : x
3050 if (KnownSrc.isKnownAlways(Mask: fcZero | fcNan)) {
3051 IRBuilderBase::InsertPointGuard Guard(Builder);
3052 Builder.SetInsertPoint(CI);
3053
3054 // fadd +/-0, 1.0 => 1.0
3055 // fadd nan, 1.0 => nan
3056 return Builder.CreateFAddFMF(L: CI->getArgOperand(i: 0),
3057 R: ConstantFP::get(Ty: VTy, V: 1.0), FMFSource: FMF);
3058 }
3059
3060 if (KnownSrc.isKnownAlways(Mask: fcInf | fcNan)) {
3061 // exp(-inf) = 0
3062 // exp(+inf) = +inf
3063 IRBuilderBase::InsertPointGuard Guard(Builder);
3064 Builder.SetInsertPoint(CI);
3065
3066 // Note: Dropping canonicalize / quiet of signaling nan.
3067 Value *X = CI->getArgOperand(i: 0);
3068 Value *IsPosInfOrNan = Builder.CreateFCmpFMF(
3069 P: FCmpInst::FCMP_UEQ, LHS: X, RHS: ConstantFP::getInfinity(Ty: VTy), FMFSource: FMF);
3070 // We do not know whether an infinity or a NaN is more likely here,
3071 // so mark the branch weights as unkown.
3072 Value *ZeroOrInf = Builder.CreateSelectFMFWithUnknownProfile(
3073 C: IsPosInfOrNan, True: X, False: ConstantFP::getZero(Ty: VTy), FMFSource: FMF, DEBUG_TYPE);
3074 return ZeroOrInf;
3075 }
3076
3077 Known = KnownFPClass::exp(Src: KnownSrc);
3078 Known.knownNot(RuleOut: ~DemandedMask);
3079
3080 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3081 KnownSrcs: KnownSrc);
3082 }
3083 case Intrinsic::log:
3084 case Intrinsic::log2:
3085 case Intrinsic::log10: {
3086 FPClassTest DemandedSrcMask = DemandedMask & (fcNan | fcPosInf);
3087 if (DemandedMask & fcNan)
3088 DemandedSrcMask |= fcNan;
3089
3090 Type *EltTy = VTy->getScalarType();
3091 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3092
3093 // log(x < 0) = nan
3094 if (DemandedMask & fcNan)
3095 DemandedSrcMask |= (fcNegative & ~fcNegZero);
3096
3097 // log(0) = -inf
3098 if (DemandedMask & fcNegInf) {
3099 DemandedSrcMask |= fcZero;
3100
3101 // No value produces subnormal result.
3102 if (Mode.inputsMayBeZero())
3103 DemandedSrcMask |= fcSubnormal;
3104 }
3105
3106 if (DemandedMask & fcNormal)
3107 DemandedSrcMask |= fcNormal | fcSubnormal;
3108
3109 // log(1) = 0
3110 if (DemandedMask & fcZero)
3111 DemandedSrcMask |= fcPosNormal;
3112
3113 KnownFPClass KnownSrc;
3114 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Depth: Depth + 1))
3115 return I;
3116
3117 Known = KnownFPClass::log(Src: KnownSrc, Mode);
3118 Known.knownNot(RuleOut: ~DemandedMask);
3119
3120 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3121 KnownSrcs: KnownSrc);
3122 }
3123 case Intrinsic::sqrt: {
3124 FPClassTest DemandedSrcMask =
3125 DemandedMask & (fcNegZero | fcPositive | fcNan);
3126
3127 if (DemandedMask & fcNan)
3128 DemandedSrcMask |= fcNan | (fcNegative & ~fcNegZero);
3129
3130 // sqrt(max_subnormal) is a normal value
3131 if (DemandedMask & fcPosNormal)
3132 DemandedSrcMask |= fcPosSubnormal;
3133
3134 KnownFPClass KnownSrc;
3135 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Depth: Depth + 1))
3136 return I;
3137
3138 // Infer the source cannot be negative if the result cannot be nan.
3139 if ((DemandedMask & fcNan) == fcNone)
3140 KnownSrc.knownNot(RuleOut: (fcNegative & ~fcNegZero) | fcNan);
3141
3142 // Infer the source cannot be +inf if the result is not +nf
3143 if ((DemandedMask & fcPosInf) == fcNone)
3144 KnownSrc.knownNot(RuleOut: fcPosInf);
3145
3146 Type *EltTy = VTy->getScalarType();
3147 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3148
3149 // sqrt(-x) = nan, but be careful of negative subnormals flushed to 0.
3150 if (KnownSrc.isKnownNever(Mask: fcPositive) &&
3151 KnownSrc.isKnownNeverLogicalZero(Mode))
3152 return ConstantFP::getQNaN(Ty: VTy);
3153
3154 Known = KnownFPClass::sqrt(Src: KnownSrc, Mode);
3155 Known.knownNot(RuleOut: ~DemandedMask);
3156
3157 if (Known.KnownFPClasses == fcZero) {
3158 if (FMF.noSignedZeros())
3159 return ConstantFP::getZero(Ty: VTy);
3160 IRBuilderBase::InsertPointGuard Guard(Builder);
3161 Builder.SetInsertPoint(CI);
3162
3163 Value *Copysign = Builder.CreateCopySign(LHS: ConstantFP::getZero(Ty: VTy),
3164 RHS: CI->getArgOperand(i: 0), FMFSource: FMF);
3165 Copysign->takeName(V: CI);
3166 return Copysign;
3167 }
3168
3169 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3170 KnownSrcs: {KnownSrc});
3171 }
3172 case Intrinsic::ldexp: {
3173 FPClassTest SrcDemandedMask = DemandedMask & fcInf;
3174 if (DemandedMask & fcNan)
3175 SrcDemandedMask |= fcNan;
3176
3177 if (DemandedMask & fcPosInf)
3178 SrcDemandedMask |= fcPosNormal | fcPosSubnormal;
3179 if (DemandedMask & fcNegInf)
3180 SrcDemandedMask |= fcNegNormal | fcNegSubnormal;
3181
3182 if (DemandedMask & (fcPosNormal | fcPosSubnormal))
3183 SrcDemandedMask |= fcPosNormal | fcPosSubnormal;
3184 if (DemandedMask & (fcNegNormal | fcNegSubnormal))
3185 SrcDemandedMask |= fcNegNormal | fcNegSubnormal;
3186
3187 if (DemandedMask & fcPosZero)
3188 SrcDemandedMask |= fcPosFinite;
3189 if (DemandedMask & fcNegZero)
3190 SrcDemandedMask |= fcNegFinite;
3191
3192 KnownFPClass KnownSrc;
3193 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Depth: Depth + 1))
3194 return CI;
3195
3196 Type *EltTy = VTy->getScalarType();
3197 const fltSemantics &FltSem = EltTy->getFltSemantics();
3198 DenormalMode Mode = F.getDenormalMode(FPType: FltSem);
3199
3200 KnownBits KnownExpBits =
3201 ::computeKnownBits(V: CI->getArgOperand(i: 1), Q: SQ, Depth: Depth + 1);
3202
3203 Known = KnownFPClass::ldexp(Src: KnownSrc, N: KnownExpBits, Flt: FltSem, Mode);
3204 Known.knownNot(RuleOut: ~DemandedMask);
3205
3206 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3207 KnownSrcs: {KnownSrc});
3208 }
3209 case Intrinsic::trunc:
3210 case Intrinsic::floor:
3211 case Intrinsic::ceil:
3212 case Intrinsic::rint:
3213 case Intrinsic::nearbyint:
3214 case Intrinsic::round:
3215 case Intrinsic::roundeven: {
3216 FPClassTest DemandedSrcMask = DemandedMask;
3217 if (DemandedMask & fcNan)
3218 DemandedSrcMask |= fcNan;
3219
3220 // Zero results imply valid subnormal sources.
3221 if (DemandedMask & fcNegZero)
3222 DemandedSrcMask |= fcNegSubnormal | fcNegNormal;
3223
3224 if (DemandedMask & fcPosZero)
3225 DemandedSrcMask |= fcPosSubnormal | fcPosNormal;
3226
3227 KnownFPClass KnownSrc;
3228 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Depth: Depth + 1))
3229 return I;
3230
3231 // Note: Possibly dropping snan quiet.
3232 if (KnownSrc.isKnownAlways(Mask: fcInf | fcNan | fcZero))
3233 return CI->getArgOperand(i: 0);
3234
3235 bool IsRoundNearestOrTrunc =
3236 IID == Intrinsic::round || IID == Intrinsic::roundeven ||
3237 IID == Intrinsic::nearbyint || IID == Intrinsic::rint ||
3238 IID == Intrinsic::trunc;
3239
3240 // Ignore denormals-as-zero, as canonicalization is not mandated.
3241 if ((IID == Intrinsic::floor || IsRoundNearestOrTrunc) &&
3242 KnownSrc.isKnownAlways(Mask: fcPosZero | fcPosSubnormal))
3243 return ConstantFP::getZero(Ty: VTy);
3244
3245 if ((IID == Intrinsic::ceil || IsRoundNearestOrTrunc) &&
3246 KnownSrc.isKnownAlways(Mask: fcNegZero | fcNegSubnormal))
3247 return ConstantFP::getZero(Ty: VTy, Negative: true);
3248
3249 if (IID == Intrinsic::floor && KnownSrc.isKnownAlways(Mask: fcNegSubnormal))
3250 return ConstantFP::get(Ty: VTy, V: -1.0);
3251
3252 if (IID == Intrinsic::ceil && KnownSrc.isKnownAlways(Mask: fcPosSubnormal))
3253 return ConstantFP::get(Ty: VTy, V: 1.0);
3254
3255 Known = KnownFPClass::roundToIntegral(
3256 Src: KnownSrc, IsTrunc: IID == Intrinsic::trunc,
3257 IsMultiUnitFPType: VTy->getScalarType()->isMultiUnitFPType());
3258
3259 Known.knownNot(RuleOut: ~DemandedMask);
3260
3261 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
3262 /*IsCanonicalizing=*/true))
3263 return SingleVal;
3264
3265 if ((IID == Intrinsic::trunc || IsRoundNearestOrTrunc) &&
3266 KnownSrc.isKnownAlways(Mask: fcZero | fcSubnormal)) {
3267 IRBuilderBase::InsertPointGuard Guard(Builder);
3268 Builder.SetInsertPoint(CI);
3269
3270 Value *Copysign = Builder.CreateCopySign(LHS: ConstantFP::getZero(Ty: VTy),
3271 RHS: CI->getArgOperand(i: 0));
3272 Copysign->takeName(V: CI);
3273 return Copysign;
3274 }
3275
3276 FastMathFlags InferredFMF =
3277 inferFastMathValueFlags(FMF, ValidResults: Known.KnownFPClasses, Known: KnownSrc);
3278 if (InferredFMF != FMF) {
3279 CI->dropUBImplyingAttrsAndMetadata();
3280 CI->setFastMathFlags(InferredFMF);
3281 return CI;
3282 }
3283
3284 return nullptr;
3285 }
3286 case Intrinsic::fptrunc_round:
3287 return simplifyDemandedUseFPClassFPTrunc(IC&: *this, I&: *CI, FMF, DemandedMask,
3288 Known, Depth);
3289 case Intrinsic::canonicalize: {
3290 Type *EltTy = VTy->getScalarType();
3291
3292 // TODO: This could have more refined support for PositiveZero denormal
3293 // mode.
3294 if (EltTy->isIEEELikeFPTy()) {
3295 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3296
3297 FPClassTest SrcDemandedMask = DemandedMask;
3298
3299 // A demanded quiet nan result may have come from a signaling nan, so we
3300 // need to expand the demanded mask.
3301 if ((DemandedMask & fcQNan) != fcNone)
3302 SrcDemandedMask |= fcSNan;
3303
3304 if (Mode != DenormalMode::getIEEE()) {
3305 // Any zero results may have come from flushed denormals.
3306 if (DemandedMask & fcPosZero)
3307 SrcDemandedMask |= fcPosSubnormal;
3308 if (DemandedMask & fcNegZero)
3309 SrcDemandedMask |= fcNegSubnormal;
3310 }
3311
3312 if (Mode == DenormalMode::getPreserveSign()) {
3313 // If a denormal input will be flushed, and we don't need zeros, we
3314 // don't need denormals either.
3315 if ((DemandedMask & fcPosZero) == fcNone)
3316 SrcDemandedMask &= ~fcPosSubnormal;
3317
3318 if ((DemandedMask & fcNegZero) == fcNone)
3319 SrcDemandedMask &= ~fcNegSubnormal;
3320 }
3321
3322 KnownFPClass KnownSrc;
3323
3324 // Simplify upstream operations before trying to simplify this call.
3325 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Depth: Depth + 1))
3326 return I;
3327
3328 // Perform the canonicalization to see if this folded to a constant.
3329 Known = KnownFPClass::canonicalize(Src: KnownSrc, DenormMode: Mode);
3330 Known.knownNot(RuleOut: ~DemandedMask);
3331
3332 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses))
3333 return SingleVal;
3334
3335 // For IEEE handling, there is only a bit change for nan inputs, so we
3336 // can drop it if we do not demand nan results or we know the input
3337 // isn't a nan.
3338 // Otherwise, we also need to avoid denormal inputs to drop the
3339 // canonicalize.
3340 if (KnownSrc.isKnownNeverNaN() && (Mode == DenormalMode::getIEEE() ||
3341 KnownSrc.isKnownNeverSubnormal()))
3342 return CI->getArgOperand(i: 0);
3343
3344 FastMathFlags InferredFMF =
3345 inferFastMathValueFlags(FMF, ValidResults: Known.KnownFPClasses, Known: KnownSrc);
3346 if (InferredFMF != FMF) {
3347 CI->dropUBImplyingAttrsAndMetadata();
3348 CI->setFastMathFlags(InferredFMF);
3349 return CI;
3350 }
3351
3352 return nullptr;
3353 }
3354
3355 [[fallthrough]];
3356 }
3357 default:
3358 Known = computeKnownFPClass(Val: I, Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3359 Known.knownNot(RuleOut: ~DemandedMask);
3360 break;
3361 }
3362
3363 break;
3364 }
3365 case Instruction::Select: {
3366 KnownFPClass KnownLHS, KnownRHS;
3367 if (SimplifyDemandedFPClass(I, Op: 2, DemandedMask, Known&: KnownRHS, Depth: Depth + 1) ||
3368 SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownLHS, Depth: Depth + 1))
3369 return I;
3370
3371 if (KnownLHS.isKnownNever(Mask: DemandedMask))
3372 return I->getOperand(i: 2);
3373 if (KnownRHS.isKnownNever(Mask: DemandedMask))
3374 return I->getOperand(i: 1);
3375
3376 adjustKnownFPClassForSelectArm(Known&: KnownLHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
3377 /*Invert=*/false, Q: SQ, Depth);
3378 adjustKnownFPClassForSelectArm(Known&: KnownRHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
3379 /*Invert=*/true, Q: SQ, Depth);
3380 Known = KnownLHS.intersectWith(RHS: KnownRHS);
3381 Known.knownNot(RuleOut: ~DemandedMask);
3382 break;
3383 }
3384 case Instruction::ExtractElement: {
3385 // TODO: Handle demanded element mask
3386 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known, Depth: Depth + 1))
3387 return I;
3388 Known.knownNot(RuleOut: ~DemandedMask);
3389 break;
3390 }
3391 case Instruction::InsertElement: {
3392 KnownFPClass KnownInserted, KnownVec;
3393 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownInserted, Depth: Depth + 1) ||
3394 SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownVec, Depth: Depth + 1))
3395 return I;
3396
3397 // TODO: Use demanded elements logic from computeKnownFPClass
3398 Known = KnownVec | KnownInserted;
3399 Known.knownNot(RuleOut: ~DemandedMask);
3400 break;
3401 }
3402 case Instruction::ShuffleVector: {
3403 KnownFPClass KnownLHS, KnownRHS;
3404 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownRHS, Depth: Depth + 1) ||
3405 SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownLHS, Depth: Depth + 1))
3406 return I;
3407
3408 // TODO: This is overly conservative and should consider demanded elements,
3409 // and splats.
3410 Known = KnownLHS | KnownRHS;
3411 Known.knownNot(RuleOut: ~DemandedMask);
3412 break;
3413 }
3414 case Instruction::ExtractValue: {
3415 Value *ExtractSrc;
3416 if (match(V: I, P: m_ExtractValue<0>(V: m_OneUse(SubPattern: m_Value(V&: ExtractSrc))))) {
3417 if (auto *II = dyn_cast<IntrinsicInst>(Val: ExtractSrc)) {
3418 const Intrinsic::ID IID = II->getIntrinsicID();
3419 switch (IID) {
3420 case Intrinsic::frexp: {
3421 FPClassTest SrcDemandedMask = fcNone;
3422 if (DemandedMask & fcNan)
3423 SrcDemandedMask |= fcNan;
3424 if (DemandedMask & fcNegFinite)
3425 SrcDemandedMask |= fcNegFinite;
3426 if (DemandedMask & fcPosFinite)
3427 SrcDemandedMask |= fcPosFinite;
3428 if (DemandedMask & fcPosInf)
3429 SrcDemandedMask |= fcPosInf;
3430 if (DemandedMask & fcNegInf)
3431 SrcDemandedMask |= fcNegInf;
3432
3433 KnownFPClass KnownSrc;
3434 if (SimplifyDemandedFPClass(I: II, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc,
3435 Depth: Depth + 1))
3436 return I;
3437
3438 Type *EltTy = VTy->getScalarType();
3439 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3440
3441 Known = KnownFPClass::frexp_mant(Src: KnownSrc, Mode);
3442 Known.KnownFPClasses &= DemandedMask;
3443
3444 if (Constant *SingleVal =
3445 getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
3446 /*IsCanonicalizing=*/true))
3447 return SingleVal;
3448
3449 if (Known.isKnownAlways(Mask: fcInf | fcNan))
3450 return II->getArgOperand(i: 0);
3451
3452 return nullptr;
3453 }
3454 default:
3455 break;
3456 }
3457 }
3458 }
3459 [[fallthrough]];
3460 }
3461 default:
3462 Known = computeKnownFPClass(Val: I, Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3463 Known.knownNot(RuleOut: ~DemandedMask);
3464 break;
3465 }
3466
3467 return getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses);
3468}
3469
3470/// Helper routine of SimplifyDemandedUseFPClass. It computes Known
3471/// floating-point classes. It also tries to handle simplifications that can be
3472/// done based on DemandedMask, but without modifying the Instruction.
3473Value *InstCombinerImpl::SimplifyMultipleUseDemandedFPClass(
3474 Instruction *I, FPClassTest DemandedMask, KnownFPClass &Known,
3475 Instruction *CxtI, unsigned Depth) {
3476 FastMathFlags FMF;
3477 if (auto *FPOp = dyn_cast<FPMathOperator>(Val: I)) {
3478 FMF = FPOp->getFastMathFlags();
3479 DemandedMask = adjustDemandedMaskFromFlags(DemandedMask, FMF);
3480 }
3481
3482 switch (I->getOpcode()) {
3483 case Instruction::Select: {
3484 // TODO: Can we infer which side it came from based on adjusted result
3485 // class?
3486 KnownFPClass KnownRHS =
3487 computeKnownFPClass(Val: I->getOperand(i: 2), Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3488 if (KnownRHS.isKnownNever(Mask: DemandedMask))
3489 return I->getOperand(i: 1);
3490
3491 KnownFPClass KnownLHS =
3492 computeKnownFPClass(Val: I->getOperand(i: 1), Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3493 if (KnownLHS.isKnownNever(Mask: DemandedMask))
3494 return I->getOperand(i: 2);
3495
3496 adjustKnownFPClassForSelectArm(Known&: KnownLHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
3497 /*Invert=*/false, Q: SQ, Depth);
3498 adjustKnownFPClassForSelectArm(Known&: KnownRHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
3499 /*Invert=*/true, Q: SQ, Depth);
3500 Known = KnownLHS.intersectWith(RHS: KnownRHS);
3501 Known.knownNot(RuleOut: ~DemandedMask);
3502 break;
3503 }
3504 case Instruction::FNeg: {
3505 // Special case fneg(fabs(x))
3506 Value *Src;
3507
3508 Value *FNegSrc = I->getOperand(i: 0);
3509 if (!match(V: FNegSrc, P: m_FAbs(Op0: m_Value(V&: Src)))) {
3510 Known = computeKnownFPClass(Val: I, Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3511 break;
3512 }
3513
3514 KnownFPClass KnownSrc =
3515 computeKnownFPClass(Val: Src, Interested: fcAllFlags, CtxI: CxtI, Depth: Depth + 1);
3516
3517 FastMathFlags FabsFMF = cast<FPMathOperator>(Val: FNegSrc)->getFastMathFlags();
3518 FPClassTest ThisDemandedMask =
3519 adjustDemandedMaskFromFlags(DemandedMask, FMF: FabsFMF);
3520
3521 // We cannot apply the NSZ logic with multiple uses. We can apply it if the
3522 // inner fabs has it and this is the only use.
3523 if (Value *Simplified = simplifyDemandedFPClassFnegFabs(
3524 Known, Src, DemandedMask: ThisDemandedMask, KnownSrc, /*NSZ=*/false))
3525 return Simplified;
3526 break;
3527 }
3528 case Instruction::Call: {
3529 const CallInst *CI = cast<CallInst>(Val: I);
3530 const Intrinsic::ID IID = CI->getIntrinsicID();
3531 switch (IID) {
3532 case Intrinsic::fabs: {
3533 Value *Src = CI->getArgOperand(i: 0);
3534 KnownFPClass KnownSrc =
3535 computeKnownFPClass(Val: Src, Interested: fcAllFlags, CtxI: CxtI, Depth: Depth + 1);
3536
3537 // NSZ cannot be applied in multiple use case (maybe it could if all uses
3538 // were known nsz)
3539 if (Value *Simplified = simplifyDemandedFPClassFabs(
3540 Known, Src: CI->getArgOperand(i: 0), DemandedMask, KnownSrc,
3541 /*NSZ=*/false))
3542 return Simplified;
3543 break;
3544 }
3545 case Intrinsic::copysign: {
3546 Value *Mag = CI->getArgOperand(i: 0);
3547 Value *Sign = CI->getArgOperand(i: 1);
3548 KnownFPClass KnownMag =
3549 computeKnownFPClass(Val: Mag, Interested: fcAllFlags, CtxI: CxtI, Depth: Depth + 1);
3550
3551 // Rule out some cases by magnitude, which may help prove the sign bit is
3552 // one direction or the other.
3553 KnownMag.knownNot(RuleOut: ~llvm::unknown_sign(Mask: DemandedMask));
3554
3555 // Cannot use nsz in the multiple use case.
3556 if (Value *Simplified = simplifyDemandedFPClassCopysignMag(
3557 MagSrc: Mag, DemandedMask, KnownSrc: KnownMag, /*NSZ=*/false))
3558 return Simplified;
3559
3560 KnownFPClass KnownSign =
3561 computeKnownFPClass(Val: Sign, Interested: fcAllFlags, CtxI: CxtI, Depth: Depth + 1);
3562
3563 if (FMF.noInfs())
3564 KnownSign.knownNot(RuleOut: fcInf);
3565 if (FMF.noNaNs())
3566 KnownSign.knownNot(RuleOut: fcNan);
3567
3568 if (KnownSign.SignBit && KnownMag.SignBit &&
3569 *KnownSign.SignBit == *KnownMag.SignBit)
3570 return Mag;
3571
3572 Known = KnownFPClass::copysign(KnownMag, KnownSign);
3573 break;
3574 }
3575 case Intrinsic::maxnum:
3576 case Intrinsic::minnum:
3577 case Intrinsic::maximum:
3578 case Intrinsic::minimum:
3579 case Intrinsic::maximumnum:
3580 case Intrinsic::minimumnum: {
3581 KnownFPClass KnownRHS = computeKnownFPClass(
3582 Val: CI->getArgOperand(i: 1), Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3583 if (KnownRHS.isUnknown())
3584 return nullptr;
3585
3586 KnownFPClass KnownLHS = computeKnownFPClass(
3587 Val: CI->getArgOperand(i: 0), Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3588
3589 // Cannot use NSZ in the multiple use case.
3590 return simplifyDemandedFPClassMinMax(Known, IID, CI, DemandedMask,
3591 KnownLHS, KnownRHS, F,
3592 /*NSZ=*/false);
3593 }
3594 default:
3595 break;
3596 }
3597
3598 [[fallthrough]];
3599 }
3600 default:
3601 Known = computeKnownFPClass(Val: I, Interested: DemandedMask, CtxI: CxtI, Depth: Depth + 1);
3602 Known.knownNot(RuleOut: ~DemandedMask);
3603 break;
3604 }
3605
3606 return getFPClassConstant(Ty: I->getType(), Mask: Known.KnownFPClasses);
3607}
3608
3609bool InstCombinerImpl::SimplifyDemandedFPClass(Instruction *I, unsigned OpNo,
3610 FPClassTest DemandedMask,
3611 KnownFPClass &Known,
3612 unsigned Depth) {
3613 Use &U = I->getOperandUse(i: OpNo);
3614 Value *V = U.get();
3615 Type *VTy = V->getType();
3616
3617 if (DemandedMask == fcNone) {
3618 if (isa<PoisonValue>(Val: V))
3619 return false;
3620 replaceUse(U, NewValue: PoisonValue::get(T: VTy));
3621 return true;
3622 }
3623
3624 // Handle constant
3625 Instruction *VInst = dyn_cast<Instruction>(Val: V);
3626 if (!VInst) {
3627 // Handle constants and arguments
3628 Known = computeKnownFPClass(Val: V, Interested: fcAllFlags, CtxI: I, Depth);
3629 Known.knownNot(RuleOut: ~DemandedMask);
3630
3631 if (Known.KnownFPClasses == fcNone) {
3632 if (isa<PoisonValue>(Val: V))
3633 return false;
3634 replaceUse(U, NewValue: PoisonValue::get(T: VTy));
3635 return true;
3636 }
3637
3638 // Do not try to replace values which are already constants (unless we are
3639 // folding to poison). Doing so could promote poison elements to non-poison
3640 // constants.
3641 if (isa<Constant>(Val: V))
3642 return false;
3643
3644 Value *FoldedToConst = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses);
3645 if (!FoldedToConst || FoldedToConst == V)
3646 return false;
3647
3648 replaceUse(U, NewValue: FoldedToConst);
3649 return true;
3650 }
3651
3652 if (const CallBase *CB = dyn_cast<CallBase>(Val: VInst)) {
3653 FPClassTest NoFPClass = CB->getParamNoFPClass(i: U.getOperandNo());
3654 DemandedMask &= ~NoFPClass;
3655 }
3656
3657 if (Depth == MaxAnalysisRecursionDepth) {
3658 Known.knownNot(RuleOut: ~DemandedMask);
3659 return false;
3660 }
3661
3662 Value *NewVal;
3663
3664 if (VInst->hasOneUse()) {
3665 // If the instruction has one use, we can directly simplify it.
3666 NewVal = SimplifyDemandedUseFPClass(I: VInst, DemandedMask, Known, CxtI: I, Depth);
3667 } else {
3668 // If there are multiple uses of this instruction, then we can simplify
3669 // VInst to some other value, but not modify the instruction.
3670 NewVal = SimplifyMultipleUseDemandedFPClass(I: VInst, DemandedMask, Known, CxtI: I,
3671 Depth);
3672 }
3673
3674 if (!NewVal)
3675 return false;
3676 if (Instruction *OpInst = dyn_cast<Instruction>(Val&: U))
3677 salvageDebugInfo(I&: *OpInst);
3678
3679 replaceUse(U, NewValue: NewVal);
3680 return true;
3681}
3682