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/ADT/SmallBitVector.h"
16#include "llvm/Analysis/ValueTracking.h"
17#include "llvm/IR/GetElementPtrTypeIterator.h"
18#include "llvm/IR/IntrinsicInst.h"
19#include "llvm/IR/PatternMatch.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 = SimplifyDemandedUseFPClass(I: &Inst, DemandedMask: fcAllFlags, Known,
154 Q: SQ.getWithInstruction(I: &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 && match(V: I->getOperand(i: 0), P: m_Ctpop(Op0: m_Value(V&: LHS))) &&
361 match(V: I->getOperand(i: 1), P: m_Ctpop(Op0: m_Value(V&: RHS)))) {
362 // (ctpop(X) ^ ctpop(Y)) & 1 --> ctpop(X^Y) & 1
363 IRBuilderBase::InsertPointGuard Guard(Builder);
364 Builder.SetInsertPoint(I);
365 auto *Xor = Builder.CreateXor(LHS, RHS);
366 return Builder.CreateUnaryIntrinsic(ID: Intrinsic::ctpop, Op: Xor);
367 }
368
369 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
370 SQ: Q, Depth);
371
372 // If the client is only demanding bits that we know, return the known
373 // constant.
374 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
375 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
376
377 // If all of the demanded bits are known zero on one side, return the other.
378 // These bits cannot contribute to the result of the 'xor'.
379 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero))
380 return I->getOperand(i: 0);
381 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero))
382 return I->getOperand(i: 1);
383
384 // If all of the demanded bits are known to be zero on one side or the
385 // other, turn this into an *inclusive* or.
386 // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
387 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero | LHSKnown.Zero)) {
388 Instruction *Or =
389 BinaryOperator::CreateOr(V1: I->getOperand(i: 0), V2: I->getOperand(i: 1));
390 if (DemandedMask.isAllOnes())
391 cast<PossiblyDisjointInst>(Val: Or)->setIsDisjoint(true);
392 Or->takeName(V: I);
393 return InsertNewInstWith(New: Or, Old: I->getIterator());
394 }
395
396 // If all of the demanded bits on one side are known, and all of the set
397 // bits on that side are also known to be set on the other side, turn this
398 // into an AND, as we know the bits will be cleared.
399 // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
400 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero|RHSKnown.One) &&
401 RHSKnown.One.isSubsetOf(RHS: LHSKnown.One)) {
402 Constant *AndC = Constant::getIntegerValue(Ty: VTy,
403 V: ~RHSKnown.One & DemandedMask);
404 Instruction *And = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: AndC);
405 return InsertNewInstWith(New: And, Old: I->getIterator());
406 }
407
408 // If the RHS is a constant, see if we can change it. Don't alter a -1
409 // constant because that's a canonical 'not' op, and that is better for
410 // combining, SCEV, and codegen.
411 const APInt *C;
412 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) && !C->isAllOnes()) {
413 if ((*C | ~DemandedMask).isAllOnes()) {
414 // Force bits to 1 to create a 'not' op.
415 I->setOperand(i: 1, Val: ConstantInt::getAllOnesValue(Ty: VTy));
416 return I;
417 }
418 // If we can't turn this into a 'not', try to shrink the constant.
419 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedMask))
420 return I;
421 }
422
423 // If our LHS is an 'and' and if it has one use, and if any of the bits we
424 // are flipping are known to be set, then the xor is just resetting those
425 // bits to zero. We can just knock out bits from the 'and' and the 'xor',
426 // simplifying both of them.
427 if (Instruction *LHSInst = dyn_cast<Instruction>(Val: I->getOperand(i: 0))) {
428 ConstantInt *AndRHS, *XorRHS;
429 if (LHSInst->getOpcode() == Instruction::And && LHSInst->hasOneUse() &&
430 match(V: I->getOperand(i: 1), P: m_ConstantInt(CI&: XorRHS)) &&
431 match(V: LHSInst->getOperand(i: 1), P: m_ConstantInt(CI&: AndRHS)) &&
432 (LHSKnown.One & RHSKnown.One & DemandedMask) != 0) {
433 APInt NewMask = ~(LHSKnown.One & RHSKnown.One & DemandedMask);
434
435 Constant *AndC = ConstantInt::get(Ty: VTy, V: NewMask & AndRHS->getValue());
436 Instruction *NewAnd = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: AndC);
437 InsertNewInstWith(New: NewAnd, Old: I->getIterator());
438
439 Constant *XorC = ConstantInt::get(Ty: VTy, V: NewMask & XorRHS->getValue());
440 Instruction *NewXor = BinaryOperator::CreateXor(V1: NewAnd, V2: XorC);
441 return InsertNewInstWith(New: NewXor, Old: I->getIterator());
442 }
443 }
444 break;
445 }
446 case Instruction::Select: {
447 if (SimplifyDemandedBits(I, OpNo: 2, DemandedMask, Known&: RHSKnown, Q, Depth: Depth + 1) ||
448 SimplifyDemandedBits(I, OpNo: 1, DemandedMask, Known&: LHSKnown, Q, Depth: Depth + 1))
449 return I;
450
451 // If the operands are constants, see if we can simplify them.
452 // This is similar to ShrinkDemandedConstant, but for a select we want to
453 // try to keep the selected constants the same as icmp value constants, if
454 // we can. This helps not break apart (or helps put back together)
455 // canonical patterns like min and max.
456 auto CanonicalizeSelectConstant = [](Instruction *I, unsigned OpNo,
457 const APInt &DemandedMask) {
458 const APInt *SelC;
459 if (!match(V: I->getOperand(i: OpNo), P: m_APInt(Res&: SelC)))
460 return false;
461
462 // Get the constant out of the ICmp, if there is one.
463 // Only try this when exactly 1 operand is a constant (if both operands
464 // are constant, the icmp should eventually simplify). Otherwise, we may
465 // invert the transform that reduces set bits and infinite-loop.
466 Value *X;
467 const APInt *CmpC;
468 if (!match(V: I->getOperand(i: 0), P: m_ICmp(L: m_Value(V&: X), R: m_APInt(Res&: CmpC))) ||
469 isa<Constant>(Val: X) || CmpC->getBitWidth() != SelC->getBitWidth())
470 return ShrinkDemandedConstant(I, OpNo, Demanded: DemandedMask);
471
472 // If the constant is already the same as the ICmp, leave it as-is.
473 if (*CmpC == *SelC)
474 return false;
475 // If the constants are not already the same, but can be with the demand
476 // mask, use the constant value from the ICmp.
477 if ((*CmpC & DemandedMask) == (*SelC & DemandedMask)) {
478 I->setOperand(i: OpNo, Val: ConstantInt::get(Ty: I->getType(), V: *CmpC));
479 return true;
480 }
481 return ShrinkDemandedConstant(I, OpNo, Demanded: DemandedMask);
482 };
483 if (CanonicalizeSelectConstant(I, 1, DemandedMask) ||
484 CanonicalizeSelectConstant(I, 2, DemandedMask))
485 return I;
486
487 // Only known if known in both the LHS and RHS.
488 adjustKnownBitsForSelectArm(Known&: LHSKnown, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
489 /*Invert=*/false, Q, Depth);
490 adjustKnownBitsForSelectArm(Known&: RHSKnown, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
491 /*Invert=*/true, Q, Depth);
492 Known = LHSKnown.intersectWith(RHS: RHSKnown);
493 break;
494 }
495 case Instruction::Trunc: {
496 // If we do not demand the high bits of a right-shifted and truncated value,
497 // then we may be able to truncate it before the shift.
498 Value *X;
499 const APInt *C;
500 if (match(V: I->getOperand(i: 0), P: m_OneUse(SubPattern: m_LShr(L: m_Value(V&: X), R: m_APInt(Res&: C))))) {
501 // The shift amount must be valid (not poison) in the narrow type, and
502 // it must not be greater than the high bits demanded of the result.
503 if (C->ult(RHS: VTy->getScalarSizeInBits()) &&
504 C->ule(RHS: DemandedMask.countl_zero())) {
505 // trunc (lshr X, C) --> lshr (trunc X), C
506 IRBuilderBase::InsertPointGuard Guard(Builder);
507 Builder.SetInsertPoint(I);
508 Value *Trunc = Builder.CreateTrunc(V: X, DestTy: VTy);
509 return Builder.CreateLShr(LHS: Trunc, RHS: C->getZExtValue());
510 }
511 }
512 }
513 [[fallthrough]];
514 case Instruction::ZExt: {
515 unsigned SrcBitWidth = I->getOperand(i: 0)->getType()->getScalarSizeInBits();
516
517 APInt InputDemandedMask = DemandedMask.zextOrTrunc(width: SrcBitWidth);
518 KnownBits InputKnown(SrcBitWidth);
519 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: InputDemandedMask, Known&: InputKnown, Q,
520 Depth: Depth + 1)) {
521 // For zext nneg, we may have dropped the instruction which made the
522 // input non-negative.
523 I->dropPoisonGeneratingFlags();
524 return I;
525 }
526 assert(InputKnown.getBitWidth() == SrcBitWidth && "Src width changed?");
527 if (I->getOpcode() == Instruction::ZExt && I->hasNonNeg() &&
528 !InputKnown.isNegative())
529 InputKnown.makeNonNegative();
530 Known = InputKnown.zextOrTrunc(BitWidth);
531
532 break;
533 }
534 case Instruction::SExt: {
535 // Compute the bits in the result that are not present in the input.
536 unsigned SrcBitWidth = I->getOperand(i: 0)->getType()->getScalarSizeInBits();
537
538 APInt InputDemandedBits = DemandedMask.trunc(width: SrcBitWidth);
539
540 // If any of the sign extended bits are demanded, we know that the sign
541 // bit is demanded.
542 if (DemandedMask.getActiveBits() > SrcBitWidth)
543 InputDemandedBits.setBit(SrcBitWidth-1);
544
545 KnownBits InputKnown(SrcBitWidth);
546 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: InputDemandedBits, Known&: InputKnown, Q, Depth: Depth + 1))
547 return I;
548
549 // If the input sign bit is known zero, or if the NewBits are not demanded
550 // convert this into a zero extension.
551 if (InputKnown.isNonNegative() ||
552 DemandedMask.getActiveBits() <= SrcBitWidth) {
553 // Convert to ZExt cast.
554 CastInst *NewCast = new ZExtInst(I->getOperand(i: 0), VTy);
555 NewCast->takeName(V: I);
556 return InsertNewInstWith(New: NewCast, Old: I->getIterator());
557 }
558
559 // If the sign bit of the input is known set or clear, then we know the
560 // top bits of the result.
561 Known = InputKnown.sext(BitWidth);
562 break;
563 }
564 case Instruction::Add: {
565 if ((DemandedMask & 1) == 0) {
566 // If we do not need the low bit, try to convert bool math to logic:
567 // add iN (zext i1 X), (sext i1 Y) --> sext (~X & Y) to iN
568 Value *X, *Y;
569 if (match(V: I, P: m_c_Add(L: m_OneUse(SubPattern: m_ZExt(Op: m_Value(V&: X))),
570 R: m_OneUse(SubPattern: m_SExt(Op: m_Value(V&: Y))))) &&
571 X->getType()->isIntOrIntVectorTy(BitWidth: 1) && X->getType() == Y->getType()) {
572 // Truth table for inputs and output signbits:
573 // X:0 | X:1
574 // ----------
575 // Y:0 | 0 | 0 |
576 // Y:1 | -1 | 0 |
577 // ----------
578 IRBuilderBase::InsertPointGuard Guard(Builder);
579 Builder.SetInsertPoint(I);
580 Value *AndNot = Builder.CreateAnd(LHS: Builder.CreateNot(V: X), RHS: Y);
581 return Builder.CreateSExt(V: AndNot, DestTy: VTy);
582 }
583
584 // add iN (sext i1 X), (sext i1 Y) --> sext (X | Y) to iN
585 if (match(V: I, P: m_Add(L: m_SExt(Op: m_Value(V&: X)), R: m_SExt(Op: m_Value(V&: Y)))) &&
586 X->getType()->isIntOrIntVectorTy(BitWidth: 1) && X->getType() == Y->getType() &&
587 (I->getOperand(i: 0)->hasOneUse() || I->getOperand(i: 1)->hasOneUse())) {
588
589 // Truth table for inputs and output signbits:
590 // X:0 | X:1
591 // -----------
592 // Y:0 | 0 | -1 |
593 // Y:1 | -1 | -1 |
594 // -----------
595 IRBuilderBase::InsertPointGuard Guard(Builder);
596 Builder.SetInsertPoint(I);
597 Value *Or = Builder.CreateOr(LHS: X, RHS: Y);
598 return Builder.CreateSExt(V: Or, DestTy: VTy);
599 }
600 }
601
602 // Right fill the mask of bits for the operands to demand the most
603 // significant bit and all those below it.
604 unsigned NLZ = DemandedMask.countl_zero();
605 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
606 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromOps) ||
607 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedFromOps, Known&: RHSKnown, Q, Depth: Depth + 1))
608 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
609
610 // If low order bits are not demanded and known to be zero in one operand,
611 // then we don't need to demand them from the other operand, since they
612 // can't cause overflow into any bits that are demanded in the result.
613 unsigned NTZ = (~DemandedMask & RHSKnown.Zero).countr_one();
614 APInt DemandedFromLHS = DemandedFromOps;
615 DemandedFromLHS.clearLowBits(loBits: NTZ);
616 if (ShrinkDemandedConstant(I, OpNo: 0, Demanded: DemandedFromLHS) ||
617 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromLHS, Known&: LHSKnown, Q, Depth: Depth + 1))
618 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
619
620 unsigned NtzLHS = (~DemandedMask & LHSKnown.Zero).countr_one();
621 APInt DemandedFromRHS = DemandedFromOps;
622 DemandedFromRHS.clearLowBits(loBits: NtzLHS);
623 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromRHS))
624 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
625
626 // If we are known to be adding zeros to every bit below
627 // the highest demanded bit, we just return the other side.
628 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
629 return I->getOperand(i: 0);
630 if (DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
631 return I->getOperand(i: 1);
632
633 // (add X, C) --> (xor X, C) IFF C is equal to the top bit of the DemandMask
634 {
635 const APInt *C;
636 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) &&
637 C->isOneBitSet(BitNo: DemandedMask.getActiveBits() - 1)) {
638 IRBuilderBase::InsertPointGuard Guard(Builder);
639 Builder.SetInsertPoint(I);
640 return Builder.CreateXor(LHS: I->getOperand(i: 0), RHS: ConstantInt::get(Ty: VTy, V: *C));
641 }
642 }
643
644 // Otherwise just compute the known bits of the result.
645 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
646 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
647 Known = KnownBits::add(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
648 break;
649 }
650 case Instruction::Sub: {
651 // Right fill the mask of bits for the operands to demand the most
652 // significant bit and all those below it.
653 unsigned NLZ = DemandedMask.countl_zero();
654 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
655 if (ShrinkDemandedConstant(I, OpNo: 1, Demanded: DemandedFromOps) ||
656 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedFromOps, Known&: RHSKnown, Q, Depth: Depth + 1))
657 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
658
659 // If low order bits are not demanded and are known to be zero in RHS,
660 // then we don't need to demand them from LHS, since they can't cause a
661 // borrow from any bits that are demanded in the result.
662 unsigned NTZ = (~DemandedMask & RHSKnown.Zero).countr_one();
663 APInt DemandedFromLHS = DemandedFromOps;
664 DemandedFromLHS.clearLowBits(loBits: NTZ);
665 if (ShrinkDemandedConstant(I, OpNo: 0, Demanded: DemandedFromLHS) ||
666 SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromLHS, Known&: LHSKnown, Q, Depth: Depth + 1))
667 return disableWrapFlagsBasedOnUnusedHighBits(I, NLZ);
668
669 // If we are known to be subtracting zeros from every bit below
670 // the highest demanded bit, we just return the other side.
671 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
672 return I->getOperand(i: 0);
673 // We can't do this with the LHS for subtraction, unless we are only
674 // demanding the LSB.
675 if (DemandedFromOps.isOne() && DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
676 return I->getOperand(i: 1);
677
678 // Canonicalize sub mask, X -> ~X
679 const APInt *LHSC;
680 if (match(V: I->getOperand(i: 0), P: m_LowBitMask(V&: LHSC)) &&
681 DemandedFromOps.isSubsetOf(RHS: *LHSC)) {
682 IRBuilderBase::InsertPointGuard Guard(Builder);
683 Builder.SetInsertPoint(I);
684 return Builder.CreateNot(V: I->getOperand(i: 1));
685 }
686
687 // Otherwise just compute the known bits of the result.
688 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
689 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
690 Known = KnownBits::sub(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
691 break;
692 }
693 case Instruction::Mul: {
694 APInt DemandedFromOps;
695 if (simplifyOperandsBasedOnUnusedHighBits(DemandedFromOps))
696 return I;
697
698 if (DemandedMask.isPowerOf2()) {
699 // The LSB of X*Y is set only if (X & 1) == 1 and (Y & 1) == 1.
700 // If we demand exactly one bit N and we have "X * (C' << N)" where C' is
701 // odd (has LSB set), then the left-shifted low bit of X is the answer.
702 unsigned CTZ = DemandedMask.countr_zero();
703 const APInt *C;
704 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: C)) && C->countr_zero() == CTZ) {
705 Constant *ShiftC = ConstantInt::get(Ty: VTy, V: CTZ);
706 Instruction *Shl = BinaryOperator::CreateShl(V1: I->getOperand(i: 0), V2: ShiftC);
707 return InsertNewInstWith(New: Shl, Old: I->getIterator());
708 }
709 }
710 // For a squared value "X * X", the bottom 2 bits are 0 and X[0] because:
711 // X * X is odd iff X is odd.
712 // 'Quadratic Reciprocity': X * X -> 0 for bit[1]
713 if (I->getOperand(i: 0) == I->getOperand(i: 1) && DemandedMask.ult(RHS: 4)) {
714 Constant *One = ConstantInt::get(Ty: VTy, V: 1);
715 Instruction *And1 = BinaryOperator::CreateAnd(V1: I->getOperand(i: 0), V2: One);
716 return InsertNewInstWith(New: And1, Old: I->getIterator());
717 }
718
719 llvm::computeKnownBits(V: I, Known, Q, Depth);
720 break;
721 }
722 case Instruction::Shl: {
723 const APInt *SA;
724 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
725 const APInt *ShrAmt;
726 if (match(V: I->getOperand(i: 0), P: m_Shr(L: m_Value(), R: m_APInt(Res&: ShrAmt))))
727 if (Instruction *Shr = dyn_cast<Instruction>(Val: I->getOperand(i: 0)))
728 if (Value *R = simplifyShrShlDemandedBits(Shr, ShrOp1: *ShrAmt, Shl: I, ShlOp1: *SA,
729 DemandedMask, Known))
730 return R;
731
732 // Do not simplify if shl is part of funnel-shift pattern
733 if (I->hasOneUse()) {
734 Instruction *Inst = I->user_back();
735 if (Inst->getOpcode() == BinaryOperator::Or) {
736 if (auto Opt = convertOrOfShiftsToFunnelShift(Or&: *Inst)) {
737 auto [IID, FShiftArgs] = *Opt;
738 if ((IID == Intrinsic::fshl || IID == Intrinsic::fshr) &&
739 FShiftArgs[0] == FShiftArgs[1]) {
740 llvm::computeKnownBits(V: I, Known, Q, Depth);
741 break;
742 }
743 }
744 }
745 }
746
747 // We only want bits that already match the signbit then we don't
748 // need to shift.
749 uint64_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth - 1);
750 if (DemandedMask.countr_zero() >= ShiftAmt) {
751 if (I->hasNoSignedWrap()) {
752 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
753 unsigned SignBits =
754 ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
755 if (SignBits > ShiftAmt && SignBits - ShiftAmt >= NumHiDemandedBits)
756 return I->getOperand(i: 0);
757 }
758
759 // If we can pre-shift a right-shifted constant to the left without
760 // losing any high bits and we don't demand the low bits, then eliminate
761 // the left-shift:
762 // (C >> X) << LeftShiftAmtC --> (C << LeftShiftAmtC) >> X
763 Value *X;
764 Constant *C;
765 if (match(V: I->getOperand(i: 0), P: m_LShr(L: m_ImmConstant(C), R: m_Value(V&: X)))) {
766 Constant *LeftShiftAmtC = ConstantInt::get(Ty: VTy, V: ShiftAmt);
767 Constant *NewC = ConstantFoldBinaryOpOperands(Opcode: Instruction::Shl, LHS: C,
768 RHS: LeftShiftAmtC, DL);
769 if (ConstantFoldBinaryOpOperands(Opcode: Instruction::LShr, LHS: NewC,
770 RHS: LeftShiftAmtC, DL) == C) {
771 Instruction *Lshr = BinaryOperator::CreateLShr(V1: NewC, V2: X);
772 return InsertNewInstWith(New: Lshr, Old: I->getIterator());
773 }
774 }
775 }
776
777 APInt DemandedMaskIn(DemandedMask.lshr(shiftAmt: ShiftAmt));
778
779 // If the shift is NUW/NSW, then it does demand the high bits.
780 ShlOperator *IOp = cast<ShlOperator>(Val: I);
781 if (IOp->hasNoSignedWrap())
782 DemandedMaskIn.setHighBits(ShiftAmt+1);
783 else if (IOp->hasNoUnsignedWrap())
784 DemandedMaskIn.setHighBits(ShiftAmt);
785
786 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1))
787 return I;
788
789 Known = KnownBits::shl(LHS: Known,
790 RHS: KnownBits::makeConstant(C: APInt(BitWidth, ShiftAmt)),
791 /* NUW */ IOp->hasNoUnsignedWrap(),
792 /* NSW */ IOp->hasNoSignedWrap());
793 } else {
794 // This is a variable shift, so we can't shift the demand mask by a known
795 // amount. But if we are not demanding high bits, then we are not
796 // demanding those bits from the pre-shifted operand either.
797 if (unsigned CTLZ = DemandedMask.countl_zero()) {
798 APInt DemandedFromOp(APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - CTLZ));
799 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedFromOp, Known, Q, Depth: Depth + 1)) {
800 // We can't guarantee that nsw/nuw hold after simplifying the operand.
801 I->dropPoisonGeneratingFlags();
802 return I;
803 }
804 }
805 llvm::computeKnownBits(V: I, Known, Q, Depth);
806 }
807 break;
808 }
809 case Instruction::LShr: {
810 const APInt *SA;
811 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
812 uint64_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth-1);
813
814 // Do not simplify if lshr is part of funnel-shift pattern
815 if (I->hasOneUse()) {
816 Instruction *Inst = I->user_back();
817 if (Inst->getOpcode() == BinaryOperator::Or) {
818 if (auto Opt = convertOrOfShiftsToFunnelShift(Or&: *Inst)) {
819 auto [IID, FShiftArgs] = *Opt;
820 if ((IID == Intrinsic::fshl || IID == Intrinsic::fshr) &&
821 FShiftArgs[0] == FShiftArgs[1]) {
822 llvm::computeKnownBits(V: I, Known, Q, Depth);
823 break;
824 }
825 }
826 }
827 }
828
829 // If we are just demanding the shifted sign bit and below, then this can
830 // be treated as an ASHR in disguise.
831 if (DemandedMask.countl_zero() >= ShiftAmt) {
832 // If we only want bits that already match the signbit then we don't
833 // need to shift.
834 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
835 unsigned SignBits =
836 ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
837 if (SignBits >= NumHiDemandedBits)
838 return I->getOperand(i: 0);
839
840 // If we can pre-shift a left-shifted constant to the right without
841 // losing any low bits (we already know we don't demand the high bits),
842 // then eliminate the right-shift:
843 // (C << X) >> RightShiftAmtC --> (C >> RightShiftAmtC) << X
844 Value *X;
845 Constant *C;
846 if (match(V: I->getOperand(i: 0), P: m_Shl(L: m_ImmConstant(C), R: m_Value(V&: X)))) {
847 Constant *RightShiftAmtC = ConstantInt::get(Ty: VTy, V: ShiftAmt);
848 Constant *NewC = ConstantFoldBinaryOpOperands(Opcode: Instruction::LShr, LHS: C,
849 RHS: RightShiftAmtC, DL);
850 if (ConstantFoldBinaryOpOperands(Opcode: Instruction::Shl, LHS: NewC,
851 RHS: RightShiftAmtC, DL) == C) {
852 Instruction *Shl = BinaryOperator::CreateShl(V1: NewC, V2: X);
853 return InsertNewInstWith(New: Shl, Old: I->getIterator());
854 }
855 }
856
857 const APInt *Factor;
858 if (match(V: I->getOperand(i: 0),
859 P: m_OneUse(SubPattern: m_Mul(L: m_Value(V&: X), R: m_APInt(Res&: Factor)))) &&
860 Factor->countr_zero() >= ShiftAmt) {
861 BinaryOperator *Mul = BinaryOperator::CreateMul(
862 V1: X, V2: ConstantInt::get(Ty: X->getType(), V: Factor->lshr(shiftAmt: ShiftAmt)));
863 return InsertNewInstWith(New: Mul, Old: I->getIterator());
864 }
865 }
866
867 // Unsigned shift right.
868 APInt DemandedMaskIn(DemandedMask.shl(shiftAmt: ShiftAmt));
869 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1)) {
870 // exact flag may not longer hold.
871 I->dropPoisonGeneratingFlags();
872 return I;
873 }
874 Known >>= ShiftAmt;
875 if (ShiftAmt)
876 Known.Zero.setHighBits(ShiftAmt); // high bits known zero.
877 break;
878 }
879 if (Value *V =
880 simplifyShiftSelectingPackedElement(I, DemandedMask, IC&: *this, Depth))
881 return V;
882
883 llvm::computeKnownBits(V: I, Known, Q, Depth);
884 break;
885 }
886 case Instruction::AShr: {
887 unsigned SignBits = ComputeNumSignBits(Op: I->getOperand(i: 0), CxtI: Q.CxtI, Depth: Depth + 1);
888
889 // If we only want bits that already match the signbit then we don't need
890 // to shift.
891 unsigned NumHiDemandedBits = BitWidth - DemandedMask.countr_zero();
892 if (SignBits >= NumHiDemandedBits)
893 return I->getOperand(i: 0);
894
895 // If this is an arithmetic shift right and only the low-bit is set, we can
896 // always convert this into a logical shr, even if the shift amount is
897 // variable. The low bit of the shift cannot be an input sign bit unless
898 // the shift amount is >= the size of the datatype, which is undefined.
899 if (DemandedMask.isOne()) {
900 // Perform the logical shift right.
901 Instruction *NewVal = BinaryOperator::CreateLShr(
902 V1: I->getOperand(i: 0), V2: I->getOperand(i: 1), Name: I->getName());
903 return InsertNewInstWith(New: NewVal, Old: I->getIterator());
904 }
905
906 const APInt *SA;
907 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
908 uint32_t ShiftAmt = SA->getLimitedValue(Limit: BitWidth-1);
909
910 // Signed shift right.
911 APInt DemandedMaskIn(DemandedMask.shl(shiftAmt: ShiftAmt));
912 // If any of the bits being shifted in are demanded, then we should set
913 // the sign bit as demanded.
914 bool ShiftedInBitsDemanded = DemandedMask.countl_zero() < ShiftAmt;
915 if (ShiftedInBitsDemanded)
916 DemandedMaskIn.setSignBit();
917 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known, Q, Depth: Depth + 1)) {
918 // exact flag may not longer hold.
919 I->dropPoisonGeneratingFlags();
920 return I;
921 }
922
923 // If the input sign bit is known to be zero, or if none of the shifted in
924 // bits are demanded, turn this into an unsigned shift right.
925 if (Known.Zero[BitWidth - 1] || !ShiftedInBitsDemanded) {
926 BinaryOperator *LShr = BinaryOperator::CreateLShr(V1: I->getOperand(i: 0),
927 V2: I->getOperand(i: 1));
928 LShr->setIsExact(cast<BinaryOperator>(Val: I)->isExact());
929 LShr->takeName(V: I);
930 return InsertNewInstWith(New: LShr, Old: I->getIterator());
931 }
932
933 Known = KnownBits::ashr(
934 LHS: Known, RHS: KnownBits::makeConstant(C: APInt(BitWidth, ShiftAmt)),
935 ShAmtNonZero: ShiftAmt != 0, Exact: I->isExact());
936 } else {
937 llvm::computeKnownBits(V: I, Known, Q, Depth);
938 }
939 break;
940 }
941 case Instruction::UDiv: {
942 // UDiv doesn't demand low bits that are zero in the divisor.
943 const APInt *SA;
944 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: SA))) {
945 // TODO: Take the demanded mask of the result into account.
946 unsigned RHSTrailingZeros = SA->countr_zero();
947 APInt DemandedMaskIn =
948 APInt::getHighBitsSet(numBits: BitWidth, hiBitsSet: BitWidth - RHSTrailingZeros);
949 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskIn, Known&: LHSKnown, Q, Depth: Depth + 1)) {
950 // We can't guarantee that "exact" is still true after changing the
951 // the dividend.
952 I->dropPoisonGeneratingFlags();
953 return I;
954 }
955
956 Known = KnownBits::udiv(LHS: LHSKnown, RHS: KnownBits::makeConstant(C: *SA),
957 Exact: cast<BinaryOperator>(Val: I)->isExact());
958 } else {
959 llvm::computeKnownBits(V: I, Known, Q, Depth);
960 }
961 break;
962 }
963 case Instruction::SRem: {
964 const APInt *Rem;
965 if (match(V: I->getOperand(i: 1), P: m_APInt(Res&: Rem)) && Rem->isPowerOf2()) {
966 if (DemandedMask.ult(RHS: *Rem)) // srem won't affect demanded bits
967 return I->getOperand(i: 0);
968
969 APInt LowBits = *Rem - 1;
970 APInt Mask2 = LowBits | APInt::getSignMask(BitWidth);
971 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: Mask2, Known&: LHSKnown, Q, Depth: Depth + 1))
972 return I;
973 Known = KnownBits::srem(LHS: LHSKnown, RHS: KnownBits::makeConstant(C: *Rem));
974 break;
975 }
976
977 llvm::computeKnownBits(V: I, Known, Q, Depth);
978 break;
979 }
980 case Instruction::Call: {
981 bool KnownBitsComputed = false;
982 if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I)) {
983 switch (II->getIntrinsicID()) {
984 case Intrinsic::abs: {
985 if (DemandedMask == 1)
986 return II->getArgOperand(i: 0);
987 break;
988 }
989 case Intrinsic::ctpop: {
990 // Checking if the number of clear bits is odd (parity)? If the type has
991 // an even number of bits, that's the same as checking if the number of
992 // set bits is odd, so we can eliminate the 'not' op.
993 Value *X;
994 if (DemandedMask == 1 && VTy->getScalarSizeInBits() % 2 == 0 &&
995 match(V: II->getArgOperand(i: 0), P: m_Not(V: m_Value(V&: X)))) {
996 Function *Ctpop = Intrinsic::getOrInsertDeclaration(
997 M: II->getModule(), id: Intrinsic::ctpop, OverloadTys: VTy);
998 return InsertNewInstWith(New: CallInst::Create(Func: Ctpop, Args: {X}), Old: I->getIterator());
999 }
1000 break;
1001 }
1002 case Intrinsic::bswap: {
1003 // If the only bits demanded come from one byte of the bswap result,
1004 // just shift the input byte into position to eliminate the bswap.
1005 unsigned NLZ = DemandedMask.countl_zero();
1006 unsigned NTZ = DemandedMask.countr_zero();
1007
1008 // Round NTZ down to the next byte. If we have 11 trailing zeros, then
1009 // we need all the bits down to bit 8. Likewise, round NLZ. If we
1010 // have 14 leading zeros, round to 8.
1011 NLZ = alignDown(Value: NLZ, Align: 8);
1012 NTZ = alignDown(Value: NTZ, Align: 8);
1013 // If we need exactly one byte, we can do this transformation.
1014 if (BitWidth - NLZ - NTZ == 8) {
1015 // Replace this with either a left or right shift to get the byte into
1016 // the right place.
1017 Instruction *NewVal;
1018 if (NLZ > NTZ)
1019 NewVal = BinaryOperator::CreateLShr(
1020 V1: II->getArgOperand(i: 0), V2: ConstantInt::get(Ty: VTy, V: NLZ - NTZ));
1021 else
1022 NewVal = BinaryOperator::CreateShl(
1023 V1: II->getArgOperand(i: 0), V2: ConstantInt::get(Ty: VTy, V: NTZ - NLZ));
1024 NewVal->takeName(V: I);
1025 return InsertNewInstWith(New: NewVal, Old: I->getIterator());
1026 }
1027 break;
1028 }
1029 case Intrinsic::ptrmask: {
1030 unsigned MaskWidth = I->getOperand(i: 1)->getType()->getScalarSizeInBits();
1031 RHSKnown = KnownBits(MaskWidth);
1032 // If either the LHS or the RHS are Zero, the result is zero.
1033 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask, Known&: LHSKnown, Q, Depth: Depth + 1) ||
1034 SimplifyDemandedBits(
1035 I, OpNo: 1, DemandedMask: (DemandedMask & ~LHSKnown.Zero).zextOrTrunc(width: MaskWidth),
1036 Known&: RHSKnown, Q, Depth: Depth + 1))
1037 return I;
1038
1039 // TODO: Should be 1-extend
1040 RHSKnown = RHSKnown.anyextOrTrunc(BitWidth);
1041
1042 Known = LHSKnown & RHSKnown;
1043 KnownBitsComputed = true;
1044
1045 // If the client is only demanding bits we know to be zero, return
1046 // `llvm.ptrmask(p, 0)`. We can't return `null` here due to pointer
1047 // provenance, but making the mask zero will be easily optimizable in
1048 // the backend.
1049 if (DemandedMask.isSubsetOf(RHS: Known.Zero) &&
1050 !match(V: I->getOperand(i: 1), P: m_Zero()))
1051 return replaceOperand(
1052 I&: *I, OpNum: 1, V: Constant::getNullValue(Ty: I->getOperand(i: 1)->getType()));
1053
1054 // Mask in demanded space does nothing.
1055 // NOTE: We may have attributes associated with the return value of the
1056 // llvm.ptrmask intrinsic that will be lost when we just return the
1057 // operand. We should try to preserve them.
1058 if (DemandedMask.isSubsetOf(RHS: RHSKnown.One | LHSKnown.Zero))
1059 return I->getOperand(i: 0);
1060
1061 // If the RHS is a constant, see if we can simplify it.
1062 if (ShrinkDemandedConstant(
1063 I, OpNo: 1, Demanded: (DemandedMask & ~LHSKnown.Zero).zextOrTrunc(width: MaskWidth)))
1064 return I;
1065
1066 // Combine:
1067 // (ptrmask (getelementptr i8, ptr p, imm i), imm mask)
1068 // -> (ptrmask (getelementptr i8, ptr p, imm (i & mask)), imm mask)
1069 // where only the low bits known to be zero in the pointer are changed
1070 Value *InnerPtr;
1071 uint64_t GEPIndex;
1072 uint64_t PtrMaskImmediate;
1073 if (match(V: I, P: m_Intrinsic<Intrinsic::ptrmask>(
1074 Ops: m_PtrAdd(PointerOp: m_Value(V&: InnerPtr), OffsetOp: m_ConstantInt(V&: GEPIndex)),
1075 Ops: m_ConstantInt(V&: PtrMaskImmediate)))) {
1076
1077 LHSKnown = computeKnownBits(V: InnerPtr, CxtI: I, Depth: Depth + 1);
1078 if (!LHSKnown.isZero()) {
1079 const unsigned trailingZeros = LHSKnown.countMinTrailingZeros();
1080 uint64_t PointerAlignBits = (uint64_t(1) << trailingZeros) - 1;
1081
1082 uint64_t HighBitsGEPIndex = GEPIndex & ~PointerAlignBits;
1083 uint64_t MaskedLowBitsGEPIndex =
1084 GEPIndex & PointerAlignBits & PtrMaskImmediate;
1085
1086 uint64_t MaskedGEPIndex = HighBitsGEPIndex | MaskedLowBitsGEPIndex;
1087
1088 if (MaskedGEPIndex != GEPIndex) {
1089 auto *GEP = cast<GEPOperator>(Val: II->getArgOperand(i: 0));
1090 Builder.SetInsertPoint(I);
1091 Type *GEPIndexType =
1092 DL.getIndexType(PtrTy: GEP->getPointerOperand()->getType());
1093 Value *MaskedGEP = Builder.CreateGEP(
1094 Ty: GEP->getSourceElementType(), Ptr: InnerPtr,
1095 IdxList: ConstantInt::get(Ty: GEPIndexType, V: MaskedGEPIndex),
1096 Name: GEP->getName(), NW: GEP->isInBounds());
1097
1098 replaceOperand(I&: *I, OpNum: 0, V: MaskedGEP);
1099 return I;
1100 }
1101 }
1102 }
1103
1104 break;
1105 }
1106
1107 case Intrinsic::fshr:
1108 case Intrinsic::fshl: {
1109 const APInt *SA;
1110 if (!match(V: I->getOperand(i: 2), P: m_APInt(Res&: SA)))
1111 break;
1112
1113 // Normalize to funnel shift left. APInt shifts of BitWidth are well-
1114 // defined, so no need to special-case zero shifts here.
1115 uint64_t ShiftAmt = SA->urem(RHS: BitWidth);
1116 if (II->getIntrinsicID() == Intrinsic::fshr)
1117 ShiftAmt = BitWidth - ShiftAmt;
1118
1119 APInt DemandedMaskLHS(DemandedMask.lshr(shiftAmt: ShiftAmt));
1120 APInt DemandedMaskRHS(DemandedMask.shl(shiftAmt: BitWidth - ShiftAmt));
1121 if (I->getOperand(i: 0) != I->getOperand(i: 1)) {
1122 if (SimplifyDemandedBits(I, OpNo: 0, DemandedMask: DemandedMaskLHS, Known&: LHSKnown, Q,
1123 Depth: Depth + 1) ||
1124 SimplifyDemandedBits(I, OpNo: 1, DemandedMask: DemandedMaskRHS, Known&: RHSKnown, Q,
1125 Depth: Depth + 1)) {
1126 // Range attribute or metadata may no longer hold.
1127 I->dropPoisonGeneratingAnnotations();
1128 return I;
1129 }
1130 } else { // fshl is a rotate
1131 // Avoid converting rotate into funnel shift.
1132 // Only simplify if one operand is constant.
1133 LHSKnown = computeKnownBits(V: I->getOperand(i: 0), CxtI: I, Depth: Depth + 1);
1134 if (DemandedMaskLHS.isSubsetOf(RHS: LHSKnown.Zero | LHSKnown.One) &&
1135 !match(V: I->getOperand(i: 0), P: m_SpecificInt(V: LHSKnown.One))) {
1136 replaceOperand(I&: *I, OpNum: 0, V: Constant::getIntegerValue(Ty: VTy, V: LHSKnown.One));
1137 return I;
1138 }
1139
1140 RHSKnown = computeKnownBits(V: I->getOperand(i: 1), CxtI: I, Depth: Depth + 1);
1141 if (DemandedMaskRHS.isSubsetOf(RHS: RHSKnown.Zero | RHSKnown.One) &&
1142 !match(V: I->getOperand(i: 1), P: m_SpecificInt(V: RHSKnown.One))) {
1143 replaceOperand(I&: *I, OpNum: 1, V: Constant::getIntegerValue(Ty: VTy, V: RHSKnown.One));
1144 return I;
1145 }
1146 }
1147
1148 LHSKnown <<= ShiftAmt;
1149 RHSKnown >>= BitWidth - ShiftAmt;
1150 Known = LHSKnown.unionWith(RHS: RHSKnown);
1151 KnownBitsComputed = true;
1152 break;
1153 }
1154 case Intrinsic::umax: {
1155 // UMax(A, C) == A if ...
1156 // The lowest non-zero bit of DemandMask is higher than the highest
1157 // non-zero bit of C.
1158 const APInt *C;
1159 unsigned CTZ = DemandedMask.countr_zero();
1160 if (match(V: II->getArgOperand(i: 1), P: m_APInt(Res&: C)) &&
1161 CTZ >= C->getActiveBits())
1162 return II->getArgOperand(i: 0);
1163 break;
1164 }
1165 case Intrinsic::umin: {
1166 // UMin(A, C) == A if ...
1167 // The lowest non-zero bit of DemandMask is higher than the highest
1168 // non-one bit of C.
1169 // This comes from using DeMorgans on the above umax example.
1170 const APInt *C;
1171 unsigned CTZ = DemandedMask.countr_zero();
1172 if (match(V: II->getArgOperand(i: 1), P: m_APInt(Res&: C)) &&
1173 CTZ >= C->getBitWidth() - C->countl_one())
1174 return II->getArgOperand(i: 0);
1175 break;
1176 }
1177 default: {
1178 // Handle target specific intrinsics
1179 std::optional<Value *> V = targetSimplifyDemandedUseBitsIntrinsic(
1180 II&: *II, DemandedMask, Known, KnownBitsComputed);
1181 if (V)
1182 return *V;
1183 break;
1184 }
1185 }
1186 }
1187
1188 if (!KnownBitsComputed)
1189 llvm::computeKnownBits(V: I, Known, Q, Depth);
1190 break;
1191 }
1192 }
1193
1194 if (I->getType()->isPointerTy()) {
1195 Align Alignment = I->getPointerAlignment(DL);
1196 Known.Zero.setLowBits(Log2(A: Alignment));
1197 }
1198
1199 // If the client is only demanding bits that we know, return the known
1200 // constant. We can't directly simplify pointers as a constant because of
1201 // pointer provenance.
1202 // TODO: We could return `(inttoptr const)` for pointers.
1203 if (!I->getType()->isPointerTy() &&
1204 DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1205 return Constant::getIntegerValue(Ty: VTy, V: Known.One);
1206
1207 if (VerifyKnownBits) {
1208 KnownBits ReferenceKnown = llvm::computeKnownBits(V: I, Q, Depth);
1209 if (Known != ReferenceKnown) {
1210 errs() << "Mismatched known bits for " << *I << " in "
1211 << I->getFunction()->getName() << "\n";
1212 errs() << "computeKnownBits(): " << ReferenceKnown << "\n";
1213 errs() << "SimplifyDemandedBits(): " << Known << "\n";
1214 std::abort();
1215 }
1216 }
1217
1218 return nullptr;
1219}
1220
1221/// Helper routine of SimplifyDemandedUseBits. It computes Known
1222/// bits. It also tries to handle simplifications that can be done based on
1223/// DemandedMask, but without modifying the Instruction.
1224Value *InstCombinerImpl::SimplifyMultipleUseDemandedBits(
1225 Instruction *I, const APInt &DemandedMask, KnownBits &Known,
1226 const SimplifyQuery &Q, unsigned Depth) {
1227 unsigned BitWidth = DemandedMask.getBitWidth();
1228 Type *ITy = I->getType();
1229
1230 KnownBits LHSKnown(BitWidth);
1231 KnownBits RHSKnown(BitWidth);
1232
1233 // Despite the fact that we can't simplify this instruction in all User's
1234 // context, we can at least compute the known bits, and we can
1235 // do simplifications that apply to *just* the one user if we know that
1236 // this instruction has a simpler value in that context.
1237 switch (I->getOpcode()) {
1238 case Instruction::And: {
1239 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1240 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1241 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1242 SQ: Q, Depth);
1243 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1244
1245 // If the client is only demanding bits that we know, return the known
1246 // constant.
1247 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1248 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1249
1250 // If all of the demanded bits are known 1 on one side, return the other.
1251 // These bits cannot contribute to the result of the 'and' in this context.
1252 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero | RHSKnown.One))
1253 return I->getOperand(i: 0);
1254 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero | LHSKnown.One))
1255 return I->getOperand(i: 1);
1256
1257 break;
1258 }
1259 case Instruction::Or: {
1260 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1261 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1262 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1263 SQ: Q, Depth);
1264 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1265
1266 // If the client is only demanding bits that we know, return the known
1267 // constant.
1268 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1269 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1270
1271 // We can simplify (X|Y) -> X or Y in the user's context if we know that
1272 // only bits from X or Y are demanded.
1273 // If all of the demanded bits are known zero on one side, return the other.
1274 // These bits cannot contribute to the result of the 'or' in this context.
1275 if (DemandedMask.isSubsetOf(RHS: LHSKnown.One | RHSKnown.Zero))
1276 return I->getOperand(i: 0);
1277 if (DemandedMask.isSubsetOf(RHS: RHSKnown.One | LHSKnown.Zero))
1278 return I->getOperand(i: 1);
1279
1280 break;
1281 }
1282 case Instruction::Xor: {
1283 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1284 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1285 Known = analyzeKnownBitsFromAndXorOr(I: cast<Operator>(Val: I), KnownLHS: LHSKnown, KnownRHS: RHSKnown,
1286 SQ: Q, Depth);
1287 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1288
1289 // If the client is only demanding bits that we know, return the known
1290 // constant.
1291 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1292 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1293
1294 // We can simplify (X^Y) -> X or Y in the user's context if we know that
1295 // only bits from X or Y are demanded.
1296 // If all of the demanded bits are known zero on one side, return the other.
1297 if (DemandedMask.isSubsetOf(RHS: RHSKnown.Zero))
1298 return I->getOperand(i: 0);
1299 if (DemandedMask.isSubsetOf(RHS: LHSKnown.Zero))
1300 return I->getOperand(i: 1);
1301
1302 break;
1303 }
1304 case Instruction::Add: {
1305 unsigned NLZ = DemandedMask.countl_zero();
1306 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
1307
1308 // If an operand adds zeros to every bit below the highest demanded bit,
1309 // that operand doesn't change the result. Return the other side.
1310 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1311 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
1312 return I->getOperand(i: 0);
1313
1314 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1315 if (DemandedFromOps.isSubsetOf(RHS: LHSKnown.Zero))
1316 return I->getOperand(i: 1);
1317
1318 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
1319 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
1320 Known = KnownBits::add(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
1321 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1322 break;
1323 }
1324 case Instruction::Sub: {
1325 unsigned NLZ = DemandedMask.countl_zero();
1326 APInt DemandedFromOps = APInt::getLowBitsSet(numBits: BitWidth, loBitsSet: BitWidth - NLZ);
1327
1328 // If an operand subtracts zeros from every bit below the highest demanded
1329 // bit, that operand doesn't change the result. Return the other side.
1330 llvm::computeKnownBits(V: I->getOperand(i: 1), Known&: RHSKnown, Q, Depth: Depth + 1);
1331 if (DemandedFromOps.isSubsetOf(RHS: RHSKnown.Zero))
1332 return I->getOperand(i: 0);
1333
1334 bool NSW = cast<OverflowingBinaryOperator>(Val: I)->hasNoSignedWrap();
1335 bool NUW = cast<OverflowingBinaryOperator>(Val: I)->hasNoUnsignedWrap();
1336 llvm::computeKnownBits(V: I->getOperand(i: 0), Known&: LHSKnown, Q, Depth: Depth + 1);
1337 Known = KnownBits::sub(LHS: LHSKnown, RHS: RHSKnown, NSW, NUW);
1338 computeKnownBitsFromContext(V: I, Known, Q, Depth);
1339 break;
1340 }
1341 case Instruction::AShr: {
1342 // Compute the Known bits to simplify things downstream.
1343 llvm::computeKnownBits(V: I, Known, Q, Depth);
1344
1345 // If this user is only demanding bits that we know, return the known
1346 // constant.
1347 if (DemandedMask.isSubsetOf(RHS: Known.Zero | Known.One))
1348 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1349
1350 // If the right shift operand 0 is a result of a left shift by the same
1351 // amount, this is probably a zero/sign extension, which may be unnecessary,
1352 // if we do not demand any of the new sign bits. So, return the original
1353 // operand instead.
1354 const APInt *ShiftRC;
1355 const APInt *ShiftLC;
1356 Value *X;
1357 unsigned BitWidth = DemandedMask.getBitWidth();
1358 if (match(V: I,
1359 P: m_AShr(L: m_Shl(L: m_Value(V&: X), R: m_APInt(Res&: ShiftLC)), R: m_APInt(Res&: ShiftRC))) &&
1360 ShiftLC == ShiftRC && ShiftLC->ult(RHS: BitWidth) &&
1361 DemandedMask.isSubsetOf(RHS: APInt::getLowBitsSet(
1362 numBits: BitWidth, loBitsSet: BitWidth - ShiftRC->getZExtValue()))) {
1363 return X;
1364 }
1365
1366 break;
1367 }
1368 default:
1369 // Compute the Known bits to simplify things downstream.
1370 llvm::computeKnownBits(V: I, Known, Q, Depth);
1371
1372 // If this user is only demanding bits that we know, return the known
1373 // constant.
1374 if (DemandedMask.isSubsetOf(RHS: Known.Zero|Known.One))
1375 return Constant::getIntegerValue(Ty: ITy, V: Known.One);
1376
1377 break;
1378 }
1379
1380 return nullptr;
1381}
1382
1383/// Helper routine of SimplifyDemandedUseBits. It tries to simplify
1384/// "E1 = (X lsr C1) << C2", where the C1 and C2 are constant, into
1385/// "E2 = X << (C2 - C1)" or "E2 = X >> (C1 - C2)", depending on the sign
1386/// of "C2-C1".
1387///
1388/// Suppose E1 and E2 are generally different in bits S={bm, bm+1,
1389/// ..., bn}, without considering the specific value X is holding.
1390/// This transformation is legal iff one of following conditions is hold:
1391/// 1) All the bit in S are 0, in this case E1 == E2.
1392/// 2) We don't care those bits in S, per the input DemandedMask.
1393/// 3) Combination of 1) and 2). Some bits in S are 0, and we don't care the
1394/// rest bits.
1395///
1396/// Currently we only test condition 2).
1397///
1398/// As with SimplifyDemandedUseBits, it returns NULL if the simplification was
1399/// not successful.
1400Value *InstCombinerImpl::simplifyShrShlDemandedBits(
1401 Instruction *Shr, const APInt &ShrOp1, Instruction *Shl,
1402 const APInt &ShlOp1, const APInt &DemandedMask, KnownBits &Known) {
1403 if (!ShlOp1 || !ShrOp1)
1404 return nullptr; // No-op.
1405
1406 Value *VarX = Shr->getOperand(i: 0);
1407 Type *Ty = VarX->getType();
1408 unsigned BitWidth = Ty->getScalarSizeInBits();
1409 if (ShlOp1.uge(RHS: BitWidth) || ShrOp1.uge(RHS: BitWidth))
1410 return nullptr; // Undef.
1411
1412 unsigned ShlAmt = ShlOp1.getZExtValue();
1413 unsigned ShrAmt = ShrOp1.getZExtValue();
1414
1415 Known.One.clearAllBits();
1416 Known.Zero.setLowBits(ShlAmt - 1);
1417 Known.Zero &= DemandedMask;
1418
1419 APInt BitMask1(APInt::getAllOnes(numBits: BitWidth));
1420 APInt BitMask2(APInt::getAllOnes(numBits: BitWidth));
1421
1422 bool isLshr = (Shr->getOpcode() == Instruction::LShr);
1423 BitMask1 = isLshr ? (BitMask1.lshr(shiftAmt: ShrAmt) << ShlAmt) :
1424 (BitMask1.ashr(ShiftAmt: ShrAmt) << ShlAmt);
1425
1426 if (ShrAmt <= ShlAmt) {
1427 BitMask2 <<= (ShlAmt - ShrAmt);
1428 } else {
1429 BitMask2 = isLshr ? BitMask2.lshr(shiftAmt: ShrAmt - ShlAmt):
1430 BitMask2.ashr(ShiftAmt: ShrAmt - ShlAmt);
1431 }
1432
1433 // Check if condition-2 (see the comment to this function) is satified.
1434 if ((BitMask1 & DemandedMask) == (BitMask2 & DemandedMask)) {
1435 if (ShrAmt == ShlAmt)
1436 return VarX;
1437
1438 if (!Shr->hasOneUse())
1439 return nullptr;
1440
1441 BinaryOperator *New;
1442 if (ShrAmt < ShlAmt) {
1443 Constant *Amt = ConstantInt::get(Ty: VarX->getType(), V: ShlAmt - ShrAmt);
1444 New = BinaryOperator::CreateShl(V1: VarX, V2: Amt);
1445 BinaryOperator *Orig = cast<BinaryOperator>(Val: Shl);
1446 New->setHasNoSignedWrap(Orig->hasNoSignedWrap());
1447 New->setHasNoUnsignedWrap(Orig->hasNoUnsignedWrap());
1448 } else {
1449 Constant *Amt = ConstantInt::get(Ty: VarX->getType(), V: ShrAmt - ShlAmt);
1450 New = isLshr ? BinaryOperator::CreateLShr(V1: VarX, V2: Amt) :
1451 BinaryOperator::CreateAShr(V1: VarX, V2: Amt);
1452 if (cast<BinaryOperator>(Val: Shr)->isExact())
1453 New->setIsExact(true);
1454 }
1455
1456 return InsertNewInstWith(New, Old: Shl->getIterator());
1457 }
1458
1459 return nullptr;
1460}
1461
1462/// Return true if the top-level all-lanes demanded-elements query can be
1463/// skipped for an intermediate insertelement chain node. This is limited to a
1464/// bounded one-use chain with distinct in-range constant indices, where SDVE
1465/// cannot remove a dead insert before hitting its depth limit.
1466static bool canSkipDemandedEltsInInsertChain(InsertElementInst &IE,
1467 unsigned VWidth,
1468 unsigned DepthLimit) {
1469 // Only skip chain nodes that feed another insertelement; the final chain root
1470 // still runs the full query.
1471 if (!IE.hasOneUse())
1472 return false;
1473 auto *UserIE = dyn_cast<InsertElementInst>(Val: IE.user_back());
1474 if (!UserIE || UserIE->getOperand(i_nocapture: 0) != &IE)
1475 return false;
1476
1477 SmallBitVector SeenIndices(VWidth);
1478 auto HasNewIndexInRange = [&](InsertElementInst &Insert) {
1479 auto *Idx = dyn_cast<ConstantInt>(Val: Insert.getOperand(i_nocapture: 2));
1480 // Let the normal SDVE path handle variable or out-of-range indices. The
1481 // latter may simplify the chain and must not be passed to getZExtValue().
1482 if (!Idx || Idx->getValue().uge(RHS: VWidth))
1483 return false;
1484
1485 unsigned Index = Idx->getZExtValue();
1486 if (SeenIndices.test(Idx: Index))
1487 return false;
1488
1489 SeenIndices.set(Index);
1490 return true;
1491 };
1492
1493 auto *Cur = &IE;
1494 for (unsigned I = 0; I != DepthLimit; ++I) {
1495 // This loop scans the same base-chain window that the SDVE query would
1496 // inspect before hitting its depth limit. With distinct insert indices in
1497 // that window, the all-lanes query cannot remove a dead insert; with
1498 // VWidth > DepthLimit, it also cannot narrow demand to a single lane.
1499 if (!HasNewIndexInRange(*Cur))
1500 return false;
1501
1502 Value *Base = Cur->getOperand(i_nocapture: 0);
1503 if (match(V: Base, P: m_Poison()))
1504 return true;
1505
1506 Cur = dyn_cast<InsertElementInst>(Val: Base);
1507 if (!Cur || !Cur->hasOneUse())
1508 return false;
1509 }
1510
1511 return true;
1512}
1513
1514/// The specified value produces a vector with any number of elements.
1515/// This method analyzes which elements of the operand are poison and
1516/// returns that information in PoisonElts.
1517///
1518/// DemandedElts contains the set of elements that are actually used by the
1519/// caller, and by default (AllowMultipleUsers equals false) the value is
1520/// simplified only if it has a single caller. If AllowMultipleUsers is set
1521/// to true, DemandedElts refers to the union of sets of elements that are
1522/// used by all callers.
1523///
1524/// If the information about demanded elements can be used to simplify the
1525/// operation, the operation is simplified, then the resultant value is
1526/// returned. This returns null if no change was made.
1527Value *InstCombinerImpl::SimplifyDemandedVectorElts(Value *V,
1528 APInt DemandedElts,
1529 APInt &PoisonElts,
1530 unsigned Depth,
1531 bool AllowMultipleUsers) {
1532 // Cannot analyze scalable type. The number of vector elements is not a
1533 // compile-time constant.
1534 if (isa<ScalableVectorType>(Val: V->getType()))
1535 return nullptr;
1536
1537 unsigned VWidth = cast<FixedVectorType>(Val: V->getType())->getNumElements();
1538 APInt EltMask(APInt::getAllOnes(numBits: VWidth));
1539 assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
1540
1541 if (match(V, P: m_Poison())) {
1542 // If the entire vector is poison, just return this info.
1543 PoisonElts = EltMask;
1544 return nullptr;
1545 }
1546
1547 if (DemandedElts.isZero()) { // If nothing is demanded, provide poison.
1548 PoisonElts = EltMask;
1549 return PoisonValue::get(T: V->getType());
1550 }
1551
1552 PoisonElts = 0;
1553
1554 if (auto *C = dyn_cast<Constant>(Val: V)) {
1555 // Check if this is identity. If so, return 0 since we are not simplifying
1556 // anything.
1557 if (DemandedElts.isAllOnes())
1558 return nullptr;
1559
1560 Type *EltTy = cast<VectorType>(Val: V->getType())->getElementType();
1561 Constant *Poison = PoisonValue::get(T: EltTy);
1562 SmallVector<Constant*, 16> Elts;
1563 for (unsigned i = 0; i != VWidth; ++i) {
1564 if (!DemandedElts[i]) { // If not demanded, set to poison.
1565 Elts.push_back(Elt: Poison);
1566 PoisonElts.setBit(i);
1567 continue;
1568 }
1569
1570 Constant *Elt = C->getAggregateElement(Elt: i);
1571 if (!Elt) return nullptr;
1572
1573 Elts.push_back(Elt);
1574 if (isa<PoisonValue>(Val: Elt)) // Already poison.
1575 PoisonElts.setBit(i);
1576 }
1577
1578 // If we changed the constant, return it.
1579 Constant *NewCV = ConstantVector::get(V: Elts);
1580 return NewCV != C ? NewCV : nullptr;
1581 }
1582
1583 // Limit search depth.
1584 if (Depth == SimplifyDemandedVectorEltsDepthLimit)
1585 return nullptr;
1586
1587 if (!AllowMultipleUsers) {
1588 // If multiple users are using the root value, proceed with
1589 // simplification conservatively assuming that all elements
1590 // are needed.
1591 if (!V->hasOneUse()) {
1592 // Quit if we find multiple users of a non-root value though.
1593 // They'll be handled when it's their turn to be visited by
1594 // the main instcombine process.
1595 if (Depth != 0)
1596 // TODO: Just compute the PoisonElts information recursively.
1597 return nullptr;
1598
1599 // Conservatively assume that all elements are needed.
1600 DemandedElts = EltMask;
1601 }
1602 }
1603
1604 Instruction *I = dyn_cast<Instruction>(Val: V);
1605 if (!I) return nullptr; // Only analyze instructions.
1606
1607 bool MadeChange = false;
1608 auto simplifyAndSetOp = [&](Instruction *Inst, unsigned OpNum,
1609 APInt Demanded, APInt &Undef) {
1610 auto *II = dyn_cast<IntrinsicInst>(Val: Inst);
1611 Value *Op = II ? II->getArgOperand(i: OpNum) : Inst->getOperand(i: OpNum);
1612 if (Value *V = SimplifyDemandedVectorElts(V: Op, DemandedElts: Demanded, PoisonElts&: Undef, Depth: Depth + 1)) {
1613 replaceOperand(I&: *Inst, OpNum, V);
1614 MadeChange = true;
1615 }
1616 };
1617
1618 APInt PoisonElts2(VWidth, 0);
1619 APInt PoisonElts3(VWidth, 0);
1620 switch (I->getOpcode()) {
1621 default: break;
1622
1623 case Instruction::GetElementPtr: {
1624 // The LangRef requires that struct geps have all constant indices. As
1625 // such, we can't convert any operand to partial undef.
1626 auto mayIndexStructType = [](GetElementPtrInst &GEP) {
1627 for (auto I = gep_type_begin(GEP), E = gep_type_end(GEP);
1628 I != E; I++)
1629 if (I.isStruct())
1630 return true;
1631 return false;
1632 };
1633 if (mayIndexStructType(cast<GetElementPtrInst>(Val&: *I)))
1634 break;
1635
1636 // Conservatively track the demanded elements back through any vector
1637 // operands we may have. We know there must be at least one, or we
1638 // wouldn't have a vector result to get here. Note that we intentionally
1639 // merge the undef bits here since gepping with either an poison base or
1640 // index results in poison.
1641 for (unsigned i = 0; i < I->getNumOperands(); i++) {
1642 if (i == 0 ? match(V: I->getOperand(i), P: m_Undef())
1643 : match(V: I->getOperand(i), P: m_Poison())) {
1644 // If the entire vector is undefined, just return this info.
1645 PoisonElts = EltMask;
1646 return nullptr;
1647 }
1648 if (I->getOperand(i)->getType()->isVectorTy()) {
1649 APInt PoisonEltsOp(VWidth, 0);
1650 simplifyAndSetOp(I, i, DemandedElts, PoisonEltsOp);
1651 // gep(x, undef) is not undef, so skip considering idx ops here
1652 // Note that we could propagate poison, but we can't distinguish between
1653 // undef & poison bits ATM
1654 if (i == 0)
1655 PoisonElts |= PoisonEltsOp;
1656 }
1657 }
1658
1659 break;
1660 }
1661 case Instruction::InsertElement: {
1662 unsigned DepthLimit = SimplifyDemandedVectorEltsDepthLimit;
1663 auto *IE = cast<InsertElementInst>(Val: I);
1664 // Skip only when SDVE cannot simplify this insert chain before the limit.
1665 if (Depth == 0 && DemandedElts.isAllOnes() && VWidth > DepthLimit &&
1666 canSkipDemandedEltsInInsertChain(IE&: *IE, VWidth, DepthLimit))
1667 return nullptr;
1668
1669 // If this is a variable index, we don't know which element it overwrites.
1670 // demand exactly the same input as we produce.
1671 ConstantInt *Idx = dyn_cast<ConstantInt>(Val: I->getOperand(i: 2));
1672 if (!Idx) {
1673 // Note that we can't propagate undef elt info, because we don't know
1674 // which elt is getting updated.
1675 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts2);
1676 break;
1677 }
1678
1679 // The element inserted overwrites whatever was there, so the input demanded
1680 // set is simpler than the output set.
1681 unsigned IdxNo = Idx->getZExtValue();
1682 APInt PreInsertDemandedElts = DemandedElts;
1683 if (IdxNo < VWidth)
1684 PreInsertDemandedElts.clearBit(BitPosition: IdxNo);
1685
1686 // If we only demand the element that is being inserted and that element
1687 // was extracted from the same index in another vector with the same type,
1688 // replace this insert with that other vector.
1689 // Note: This is attempted before the call to simplifyAndSetOp because that
1690 // may change PoisonElts to a value that does not match with Vec.
1691 Value *Vec;
1692 if (PreInsertDemandedElts == 0 &&
1693 match(V: I->getOperand(i: 1),
1694 P: m_ExtractElt(Val: m_Value(V&: Vec), Idx: m_SpecificInt(V: IdxNo))) &&
1695 Vec->getType() == I->getType()) {
1696 return Vec;
1697 }
1698
1699 simplifyAndSetOp(I, 0, PreInsertDemandedElts, PoisonElts);
1700
1701 // If this is inserting an element that isn't demanded, remove this
1702 // insertelement.
1703 if (IdxNo >= VWidth || !DemandedElts[IdxNo]) {
1704 Worklist.push(I);
1705 return I->getOperand(i: 0);
1706 }
1707
1708 // The inserted element is defined.
1709 PoisonElts.clearBit(BitPosition: IdxNo);
1710 break;
1711 }
1712 case Instruction::ShuffleVector: {
1713 auto *Shuffle = cast<ShuffleVectorInst>(Val: I);
1714 assert(Shuffle->getOperand(0)->getType() ==
1715 Shuffle->getOperand(1)->getType() &&
1716 "Expected shuffle operands to have same type");
1717 unsigned OpWidth = cast<FixedVectorType>(Val: Shuffle->getOperand(i_nocapture: 0)->getType())
1718 ->getNumElements();
1719 // Handle trivial case of a splat. Only check the first element of LHS
1720 // operand.
1721 if (all_of(Range: Shuffle->getShuffleMask(), P: equal_to(Arg: 0)) &&
1722 DemandedElts.isAllOnes()) {
1723 if (!isa<PoisonValue>(Val: I->getOperand(i: 1))) {
1724 I->setOperand(i: 1, Val: PoisonValue::get(T: I->getOperand(i: 1)->getType()));
1725 MadeChange = true;
1726 }
1727 APInt LeftDemanded(OpWidth, 1);
1728 APInt LHSPoisonElts(OpWidth, 0);
1729 simplifyAndSetOp(I, 0, LeftDemanded, LHSPoisonElts);
1730 if (LHSPoisonElts[0])
1731 PoisonElts = EltMask;
1732 else
1733 PoisonElts.clearAllBits();
1734 break;
1735 }
1736
1737 APInt LeftDemanded(OpWidth, 0), RightDemanded(OpWidth, 0);
1738 for (unsigned i = 0; i < VWidth; i++) {
1739 if (DemandedElts[i]) {
1740 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1741 if (MaskVal != -1u) {
1742 assert(MaskVal < OpWidth * 2 &&
1743 "shufflevector mask index out of range!");
1744 if (MaskVal < OpWidth)
1745 LeftDemanded.setBit(MaskVal);
1746 else
1747 RightDemanded.setBit(MaskVal - OpWidth);
1748 }
1749 }
1750 }
1751
1752 APInt LHSPoisonElts(OpWidth, 0);
1753 simplifyAndSetOp(I, 0, LeftDemanded, LHSPoisonElts);
1754
1755 APInt RHSPoisonElts(OpWidth, 0);
1756 simplifyAndSetOp(I, 1, RightDemanded, RHSPoisonElts);
1757
1758 // If this shuffle does not change the vector length and the elements
1759 // demanded by this shuffle are an identity mask, then this shuffle is
1760 // unnecessary.
1761 //
1762 // We are assuming canonical form for the mask, so the source vector is
1763 // operand 0 and operand 1 is not used.
1764 //
1765 // Note that if an element is demanded and this shuffle mask is undefined
1766 // for that element, then the shuffle is not considered an identity
1767 // operation. The shuffle prevents poison from the operand vector from
1768 // leaking to the result by replacing poison with an undefined value.
1769 if (VWidth == OpWidth) {
1770 bool IsIdentityShuffle = true;
1771 for (unsigned i = 0; i < VWidth; i++) {
1772 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1773 if (DemandedElts[i] && i != MaskVal) {
1774 IsIdentityShuffle = false;
1775 break;
1776 }
1777 }
1778 if (IsIdentityShuffle)
1779 return Shuffle->getOperand(i_nocapture: 0);
1780 }
1781
1782 bool NewPoisonElts = false;
1783 unsigned LHSIdx = -1u, LHSValIdx = -1u;
1784 unsigned RHSIdx = -1u, RHSValIdx = -1u;
1785 bool LHSUniform = true;
1786 bool RHSUniform = true;
1787 for (unsigned i = 0; i < VWidth; i++) {
1788 unsigned MaskVal = Shuffle->getMaskValue(Elt: i);
1789 if (MaskVal == -1u) {
1790 PoisonElts.setBit(i);
1791 } else if (!DemandedElts[i]) {
1792 NewPoisonElts = true;
1793 PoisonElts.setBit(i);
1794 } else if (MaskVal < OpWidth) {
1795 if (LHSPoisonElts[MaskVal]) {
1796 NewPoisonElts = true;
1797 PoisonElts.setBit(i);
1798 } else {
1799 LHSIdx = LHSIdx == -1u ? i : OpWidth;
1800 LHSValIdx = LHSValIdx == -1u ? MaskVal : OpWidth;
1801 LHSUniform = LHSUniform && (MaskVal == i);
1802 }
1803 } else {
1804 if (RHSPoisonElts[MaskVal - OpWidth]) {
1805 NewPoisonElts = true;
1806 PoisonElts.setBit(i);
1807 } else {
1808 RHSIdx = RHSIdx == -1u ? i : OpWidth;
1809 RHSValIdx = RHSValIdx == -1u ? MaskVal - OpWidth : OpWidth;
1810 RHSUniform = RHSUniform && (MaskVal - OpWidth == i);
1811 }
1812 }
1813 }
1814
1815 // Try to transform shuffle with constant vector and single element from
1816 // this constant vector to single insertelement instruction.
1817 // shufflevector V, C, <v1, v2, .., ci, .., vm> ->
1818 // insertelement V, C[ci], ci-n
1819 if (OpWidth ==
1820 cast<FixedVectorType>(Val: Shuffle->getType())->getNumElements()) {
1821 Value *Op = nullptr;
1822 Constant *Value = nullptr;
1823 unsigned Idx = -1u;
1824
1825 // Find constant vector with the single element in shuffle (LHS or RHS).
1826 if (LHSIdx < OpWidth && RHSUniform) {
1827 if (auto *CV = dyn_cast<ConstantVector>(Val: Shuffle->getOperand(i_nocapture: 0))) {
1828 Op = Shuffle->getOperand(i_nocapture: 1);
1829 Value = CV->getOperand(i_nocapture: LHSValIdx);
1830 Idx = LHSIdx;
1831 }
1832 }
1833 if (RHSIdx < OpWidth && LHSUniform) {
1834 if (auto *CV = dyn_cast<ConstantVector>(Val: Shuffle->getOperand(i_nocapture: 1))) {
1835 Op = Shuffle->getOperand(i_nocapture: 0);
1836 Value = CV->getOperand(i_nocapture: RHSValIdx);
1837 Idx = RHSIdx;
1838 }
1839 }
1840 // Found constant vector with single element - convert to insertelement.
1841 if (Op && Value) {
1842 Instruction *New = InsertElementInst::Create(
1843 Vec: Op, NewElt: Value, Idx: ConstantInt::get(Ty: Type::getInt64Ty(C&: I->getContext()), V: Idx),
1844 NameStr: Shuffle->getName());
1845 InsertNewInstWith(New, Old: Shuffle->getIterator());
1846 return New;
1847 }
1848 }
1849 if (NewPoisonElts) {
1850 // Add additional discovered undefs.
1851 SmallVector<int, 16> Elts;
1852 for (unsigned i = 0; i < VWidth; ++i) {
1853 if (PoisonElts[i])
1854 Elts.push_back(Elt: PoisonMaskElem);
1855 else
1856 Elts.push_back(Elt: Shuffle->getMaskValue(Elt: i));
1857 }
1858 Shuffle->setShuffleMask(Elts);
1859 MadeChange = true;
1860 }
1861 break;
1862 }
1863 case Instruction::Select: {
1864 // If this is a vector select, try to transform the select condition based
1865 // on the current demanded elements.
1866 SelectInst *Sel = cast<SelectInst>(Val: I);
1867 if (Sel->getCondition()->getType()->isVectorTy()) {
1868 // TODO: We are not doing anything with PoisonElts based on this call.
1869 // It is overwritten below based on the other select operands. If an
1870 // element of the select condition is known undef, then we are free to
1871 // choose the output value from either arm of the select. If we know that
1872 // one of those values is undef, then the output can be undef.
1873 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
1874 }
1875
1876 // Next, see if we can transform the arms of the select.
1877 APInt DemandedLHS(DemandedElts), DemandedRHS(DemandedElts);
1878 if (auto *CV = dyn_cast<ConstantVector>(Val: Sel->getCondition())) {
1879 for (unsigned i = 0; i < VWidth; i++) {
1880 Constant *CElt = CV->getAggregateElement(Elt: i);
1881
1882 // isNullValue() always returns false when called on a ConstantExpr.
1883 if (CElt->isNullValue())
1884 DemandedLHS.clearBit(BitPosition: i);
1885 else if (CElt->isOneValue())
1886 DemandedRHS.clearBit(BitPosition: i);
1887 }
1888 }
1889
1890 simplifyAndSetOp(I, 1, DemandedLHS, PoisonElts2);
1891 simplifyAndSetOp(I, 2, DemandedRHS, PoisonElts3);
1892
1893 // Output elements are undefined if the element from each arm is undefined.
1894 // TODO: This can be improved. See comment in select condition handling.
1895 PoisonElts = PoisonElts2 & PoisonElts3;
1896 break;
1897 }
1898 case Instruction::BitCast: {
1899 // Vector->vector casts only.
1900 VectorType *VTy = dyn_cast<VectorType>(Val: I->getOperand(i: 0)->getType());
1901 if (!VTy) break;
1902 unsigned InVWidth = cast<FixedVectorType>(Val: VTy)->getNumElements();
1903 APInt InputDemandedElts(InVWidth, 0);
1904 PoisonElts2 = APInt(InVWidth, 0);
1905 unsigned Ratio;
1906
1907 if (VWidth == InVWidth) {
1908 // If we are converting from <4 x i32> -> <4 x f32>, we demand the same
1909 // elements as are demanded of us.
1910 Ratio = 1;
1911 InputDemandedElts = DemandedElts;
1912 } else if ((VWidth % InVWidth) == 0) {
1913 // If the number of elements in the output is a multiple of the number of
1914 // elements in the input then an input element is live if any of the
1915 // corresponding output elements are live.
1916 Ratio = VWidth / InVWidth;
1917 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1918 if (DemandedElts[OutIdx])
1919 InputDemandedElts.setBit(OutIdx / Ratio);
1920 } else if ((InVWidth % VWidth) == 0) {
1921 // If the number of elements in the input is a multiple of the number of
1922 // elements in the output then an input element is live if the
1923 // corresponding output element is live.
1924 Ratio = InVWidth / VWidth;
1925 for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
1926 if (DemandedElts[InIdx / Ratio])
1927 InputDemandedElts.setBit(InIdx);
1928 } else {
1929 // Unsupported so far.
1930 break;
1931 }
1932
1933 simplifyAndSetOp(I, 0, InputDemandedElts, PoisonElts2);
1934
1935 if (VWidth == InVWidth) {
1936 PoisonElts = PoisonElts2;
1937 } else if ((VWidth % InVWidth) == 0) {
1938 // If the number of elements in the output is a multiple of the number of
1939 // elements in the input then an output element is undef if the
1940 // corresponding input element is undef.
1941 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
1942 if (PoisonElts2[OutIdx / Ratio])
1943 PoisonElts.setBit(OutIdx);
1944 } else if ((InVWidth % VWidth) == 0) {
1945 // If the number of elements in the input is a multiple of the number of
1946 // elements in the output then an output element is undef if all of the
1947 // corresponding input elements are undef.
1948 for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
1949 APInt SubUndef = PoisonElts2.lshr(shiftAmt: OutIdx * Ratio).zextOrTrunc(width: Ratio);
1950 if (SubUndef.popcount() == Ratio)
1951 PoisonElts.setBit(OutIdx);
1952 }
1953 } else {
1954 llvm_unreachable("Unimp");
1955 }
1956 break;
1957 }
1958 case Instruction::FPTrunc:
1959 case Instruction::FPExt:
1960 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
1961 break;
1962
1963 case Instruction::Call: {
1964 IntrinsicInst *II = dyn_cast<IntrinsicInst>(Val: I);
1965 if (!II) break;
1966 switch (II->getIntrinsicID()) {
1967 case Intrinsic::masked_gather: // fallthrough
1968 case Intrinsic::masked_load: {
1969 // Subtlety: If we load from a pointer, the pointer must be valid
1970 // regardless of whether the element is demanded. Doing otherwise risks
1971 // segfaults which didn't exist in the original program.
1972 APInt DemandedPtrs(APInt::getAllOnes(numBits: VWidth)),
1973 DemandedPassThrough(DemandedElts);
1974 if (auto *CMask = dyn_cast<Constant>(Val: II->getOperand(i_nocapture: 1))) {
1975 for (unsigned i = 0; i < VWidth; i++) {
1976 if (Constant *CElt = CMask->getAggregateElement(Elt: i)) {
1977 if (CElt->isNullValue())
1978 DemandedPtrs.clearBit(BitPosition: i);
1979 else if (CElt->isAllOnesValue())
1980 DemandedPassThrough.clearBit(BitPosition: i);
1981 }
1982 }
1983 }
1984
1985 if (II->getIntrinsicID() == Intrinsic::masked_gather)
1986 simplifyAndSetOp(II, 0, DemandedPtrs, PoisonElts2);
1987 simplifyAndSetOp(II, 2, DemandedPassThrough, PoisonElts3);
1988
1989 // Output elements are undefined if the element from both sources are.
1990 // TODO: can strengthen via mask as well.
1991 PoisonElts = PoisonElts2 & PoisonElts3;
1992 break;
1993 }
1994 default: {
1995 // Handle target specific intrinsics
1996 std::optional<Value *> V = targetSimplifyDemandedVectorEltsIntrinsic(
1997 II&: *II, DemandedElts, UndefElts&: PoisonElts, UndefElts2&: PoisonElts2, UndefElts3&: PoisonElts3,
1998 SimplifyAndSetOp: simplifyAndSetOp);
1999 if (V)
2000 return *V;
2001 break;
2002 }
2003 } // switch on IntrinsicID
2004 break;
2005 } // case Call
2006 } // switch on Opcode
2007
2008 // TODO: We bail completely on integer div/rem and shifts because they have
2009 // UB/poison potential, but that should be refined.
2010 BinaryOperator *BO;
2011 if (match(V: I, P: m_BinOp(I&: BO)) && !BO->isIntDivRem() && !BO->isShift()) {
2012 Value *X = BO->getOperand(i_nocapture: 0);
2013 Value *Y = BO->getOperand(i_nocapture: 1);
2014
2015 // Look for an equivalent binop except that one operand has been shuffled.
2016 // If the demand for this binop only includes elements that are the same as
2017 // the other binop, then we may be able to replace this binop with a use of
2018 // the earlier one.
2019 //
2020 // Example:
2021 // %other_bo = bo (shuf X, {0}), Y
2022 // %this_extracted_bo = extelt (bo X, Y), 0
2023 // -->
2024 // %other_bo = bo (shuf X, {0}), Y
2025 // %this_extracted_bo = extelt %other_bo, 0
2026 //
2027 // TODO: Handle demand of an arbitrary single element or more than one
2028 // element instead of just element 0.
2029 // TODO: Unlike general demanded elements transforms, this should be safe
2030 // for any (div/rem/shift) opcode too.
2031 if (DemandedElts == 1 && !X->hasOneUse() && !Y->hasOneUse() &&
2032 BO->hasOneUse() ) {
2033
2034 auto findShufBO = [&](bool MatchShufAsOp0) -> User * {
2035 // Try to use shuffle-of-operand in place of an operand:
2036 // bo X, Y --> bo (shuf X), Y
2037 // bo X, Y --> bo X, (shuf Y)
2038
2039 Value *OtherOp = MatchShufAsOp0 ? Y : X;
2040 if (!OtherOp->hasUseList())
2041 return nullptr;
2042
2043 BinaryOperator::BinaryOps Opcode = BO->getOpcode();
2044 Value *ShufOp = MatchShufAsOp0 ? X : Y;
2045
2046 for (User *U : OtherOp->users()) {
2047 ArrayRef<int> Mask;
2048 auto Shuf = m_Shuffle(v1: m_Specific(V: ShufOp), v2: m_Value(), mask: m_Mask(Mask));
2049 if (BO->isCommutative()
2050 ? match(V: U, P: m_c_BinOp(Opcode, L: Shuf, R: m_Specific(V: OtherOp)))
2051 : MatchShufAsOp0
2052 ? match(V: U, P: m_BinOp(Opcode, L: Shuf, R: m_Specific(V: OtherOp)))
2053 : match(V: U, P: m_BinOp(Opcode, L: m_Specific(V: OtherOp), R: Shuf)))
2054 if (match(Mask, P: m_ZeroMask()) && Mask[0] != PoisonMaskElem)
2055 if (DT.dominates(Def: U, User: I))
2056 return U;
2057 }
2058 return nullptr;
2059 };
2060
2061 User *ShufBO = findShufBO(/* MatchShufAsOp0 */ true);
2062 if (!ShufBO)
2063 ShufBO = findShufBO(/* MatchShufAsOp0 */ false);
2064 if (ShufBO) {
2065 auto *ShufBOI = cast<Instruction>(Val: ShufBO);
2066 ShufBOI->andIRFlags(V: BO);
2067 Worklist.add(I: ShufBOI);
2068 return ShufBO;
2069 }
2070 }
2071
2072 simplifyAndSetOp(I, 0, DemandedElts, PoisonElts);
2073 simplifyAndSetOp(I, 1, DemandedElts, PoisonElts2);
2074
2075 // Output elements are undefined if both are undefined. Consider things
2076 // like undef & 0. The result is known zero, not undef.
2077 PoisonElts &= PoisonElts2;
2078 }
2079
2080 // If we've proven all of the lanes poison, return a poison value.
2081 // TODO: Intersect w/demanded lanes
2082 if (PoisonElts.isAllOnes())
2083 return PoisonValue::get(T: I->getType());
2084
2085 return MadeChange ? I : nullptr;
2086}
2087
2088/// For floating-point classes that resolve to a single bit pattern, return that
2089/// value.
2090static Constant *getFPClassConstant(Type *Ty, FPClassTest Mask,
2091 bool IsCanonicalizing = false) {
2092 if (Mask == fcNone)
2093 return PoisonValue::get(T: Ty);
2094
2095 if (Mask == fcPosZero)
2096 return Constant::getNullValue(Ty);
2097
2098 // TODO: Support aggregate types that are allowed by FPMathOperator.
2099 if (Ty->isAggregateType())
2100 return nullptr;
2101
2102 // Turn any possible snans into quiet if we can.
2103 if (Mask == fcNan && IsCanonicalizing)
2104 return ConstantFP::getQNaN(Ty);
2105
2106 switch (Mask) {
2107 case fcNegZero:
2108 return ConstantFP::getZero(Ty, Negative: true);
2109 case fcPosInf:
2110 return ConstantFP::getInfinity(Ty);
2111 case fcNegInf:
2112 return ConstantFP::getInfinity(Ty, Negative: true);
2113 case fcQNan:
2114 // Payload bits cannot be dropped for pure signbit operations.
2115 return IsCanonicalizing ? ConstantFP::getQNaN(Ty) : nullptr;
2116 default:
2117 return nullptr;
2118 }
2119}
2120
2121/// Perform multiple-use aware simplfications for fabs(\p Src). Returns a
2122/// replacement value if it's simplified, otherwise nullptr. Updates \p Known
2123/// with the known fpclass if not simplified.
2124static Value *simplifyDemandedFPClassFabs(KnownFPClass &Known, Value *Src,
2125 FPClassTest DemandedMask,
2126 KnownFPClass KnownSrc, bool NSZ) {
2127 if ((DemandedMask & fcNan) == fcNone)
2128 KnownSrc.knownNot(RuleOut: fcNan);
2129 if ((DemandedMask & fcInf) == fcNone)
2130 KnownSrc.knownNot(RuleOut: fcInf);
2131
2132 if (KnownSrc.SignBit == false ||
2133 ((DemandedMask & fcNan) == fcNone && KnownSrc.isKnownNever(Mask: fcNegative)))
2134 return Src;
2135
2136 // If the only sign bit difference is due to -0, ignore it with nsz
2137 if (NSZ &&
2138 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedLessThanZeroMask | fcNan))
2139 return Src;
2140
2141 Known = KnownFPClass::fabs(Src: KnownSrc);
2142 Known.knownNot(RuleOut: ~DemandedMask);
2143 return nullptr;
2144}
2145
2146/// Try to set an inferred no-nans or no-infs in \p FMF. \p ValidResults is a
2147/// mask of known valid results for the operator (already computed from the
2148/// result, and the known operand inputs in \p Known)
2149static FastMathFlags inferFastMathValueFlags(FastMathFlags FMF,
2150 FPClassTest ValidResults,
2151 ArrayRef<KnownFPClass> Known) {
2152 if (!FMF.noNaNs() && (ValidResults & fcNan) == fcNone) {
2153 if (all_of(Range&: Known, P: [](const KnownFPClass KnownSrc) {
2154 return KnownSrc.isKnownNeverNaN();
2155 }))
2156 FMF.setNoNaNs();
2157 }
2158
2159 if (!FMF.noInfs() && (ValidResults & fcInf) == fcNone) {
2160 if (all_of(Range&: Known, P: [](const KnownFPClass KnownSrc) {
2161 return KnownSrc.isKnownNeverInfinity();
2162 }))
2163 FMF.setNoInfs();
2164 }
2165
2166 return FMF;
2167}
2168
2169static FPClassTest adjustDemandedMaskFromFlags(FPClassTest DemandedMask,
2170 FastMathFlags FMF) {
2171 if (FMF.noNaNs())
2172 DemandedMask &= ~fcNan;
2173
2174 if (FMF.noInfs())
2175 DemandedMask &= ~fcInf;
2176 return DemandedMask;
2177}
2178
2179/// Apply epilog fixups to a floating-point intrinsic. See if the result can
2180/// fold to a constant, or apply fast math flags.
2181static Value *simplifyDemandedFPClassResult(Instruction *FPOp,
2182 FastMathFlags FMF,
2183 FPClassTest DemandedMask,
2184 KnownFPClass &Known,
2185 ArrayRef<KnownFPClass> KnownSrcs) {
2186 FPClassTest ValidResults = DemandedMask & Known.KnownFPClasses;
2187 Constant *SingleVal = getFPClassConstant(Ty: FPOp->getType(), Mask: ValidResults,
2188 /*IsCanonicalizing=*/true);
2189 if (SingleVal)
2190 return SingleVal;
2191
2192 FastMathFlags InferredFMF =
2193 inferFastMathValueFlags(FMF, ValidResults, Known: KnownSrcs);
2194 if (InferredFMF != FMF) {
2195 FPOp->dropUBImplyingAttrsAndMetadata();
2196 FPOp->setFastMathFlags(InferredFMF);
2197 return FPOp;
2198 }
2199
2200 return nullptr;
2201}
2202
2203/// Perform multiple-use aware simplfications for fneg(fabs(\p Src)). Returns a
2204/// replacement value if it's simplified, otherwise nullptr. Updates \p Known
2205/// with the known fpclass if not simplified.
2206static Value *simplifyDemandedFPClassFnegFabs(KnownFPClass &Known, Value *Src,
2207 FPClassTest DemandedMask,
2208 KnownFPClass KnownSrc, bool NSZ) {
2209 if ((DemandedMask & fcNan) == fcNone)
2210 KnownSrc.knownNot(RuleOut: fcNan);
2211 if ((DemandedMask & fcInf) == fcNone)
2212 KnownSrc.knownNot(RuleOut: fcInf);
2213
2214 // If the source value is known negative, we can directly fold to it.
2215 if (KnownSrc.SignBit == true)
2216 return Src;
2217
2218 // If the only sign bit difference is for 0, ignore it with nsz.
2219 if (NSZ &&
2220 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedGreaterThanZeroMask | fcNan))
2221 return Src;
2222
2223 Known = KnownFPClass::fneg(Src: KnownFPClass::fabs(Src: KnownSrc));
2224 Known.knownNot(RuleOut: ~DemandedMask);
2225 return nullptr;
2226}
2227
2228static Value *simplifyDemandedFPClassCopysignMag(Value *MagSrc,
2229 FPClassTest DemandedMask,
2230 KnownFPClass KnownSrc,
2231 bool NSZ) {
2232 if (NSZ) {
2233 constexpr FPClassTest NegOrZero = fcNegative | fcPosZero;
2234 constexpr FPClassTest PosOrZero = fcPositive | fcNegZero;
2235
2236 if ((DemandedMask & ~NegOrZero) == fcNone &&
2237 KnownSrc.isKnownAlways(Mask: NegOrZero))
2238 return MagSrc;
2239
2240 if ((DemandedMask & ~PosOrZero) == fcNone &&
2241 KnownSrc.isKnownAlways(Mask: PosOrZero))
2242 return MagSrc;
2243 } else {
2244 if ((DemandedMask & ~fcNegative) == fcNone && KnownSrc.SignBit == true)
2245 return MagSrc;
2246
2247 if ((DemandedMask & ~fcPositive) == fcNone && KnownSrc.SignBit == false)
2248 return MagSrc;
2249 }
2250
2251 return nullptr;
2252}
2253
2254static Value *
2255simplifyDemandedFPClassMinMax(KnownFPClass &Known, Intrinsic::ID IID,
2256 const CallInst *CI, FPClassTest DemandedMask,
2257 KnownFPClass KnownLHS, KnownFPClass KnownRHS,
2258 const Function &F, bool NSZ) {
2259 bool OrderedZeroSign = !NSZ;
2260
2261 KnownFPClass::MinMaxKind OpKind;
2262 switch (IID) {
2263 case Intrinsic::maximum: {
2264 OpKind = KnownFPClass::MinMaxKind::maximum;
2265
2266 // If one operand is known greater than the other, it must be that
2267 // operand unless the other is a nan.
2268 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2269 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2270 KnownRHS.isKnownNever(Mask: fcNan))
2271 return CI->getArgOperand(i: 0);
2272
2273 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2274 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2275 KnownLHS.isKnownNever(Mask: fcNan))
2276 return CI->getArgOperand(i: 1);
2277
2278 break;
2279 }
2280 case Intrinsic::minimum: {
2281 OpKind = KnownFPClass::MinMaxKind::minimum;
2282
2283 // If one operand is known less than the other, it must be that operand
2284 // unless the other is a nan.
2285 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2286 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2287 KnownRHS.isKnownNever(Mask: fcNan))
2288 return CI->getArgOperand(i: 0);
2289
2290 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2291 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2292 KnownLHS.isKnownNever(Mask: fcNan))
2293 return CI->getArgOperand(i: 1);
2294
2295 break;
2296 }
2297 case Intrinsic::maxnum:
2298 case Intrinsic::maximumnum: {
2299 OpKind = IID == Intrinsic::maxnum ? KnownFPClass::MinMaxKind::maxnum
2300 : KnownFPClass::MinMaxKind::maximumnum;
2301
2302 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2303 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2304 KnownLHS.isKnownNever(Mask: fcNan))
2305 return CI->getArgOperand(i: 0);
2306
2307 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2308 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2309 KnownRHS.isKnownNever(Mask: fcNan))
2310 return CI->getArgOperand(i: 1);
2311
2312 break;
2313 }
2314 case Intrinsic::minnum:
2315 case Intrinsic::minimumnum: {
2316 OpKind = IID == Intrinsic::minnum ? KnownFPClass::MinMaxKind::minnum
2317 : KnownFPClass::MinMaxKind::minimumnum;
2318
2319 if (cannotOrderStrictlyGreater(LHS: KnownLHS.KnownFPClasses,
2320 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2321 KnownLHS.isKnownNever(Mask: fcNan))
2322 return CI->getArgOperand(i: 0);
2323
2324 if (cannotOrderStrictlyLess(LHS: KnownLHS.KnownFPClasses,
2325 RHS: KnownRHS.KnownFPClasses, OrderedZeroSign) &&
2326 KnownRHS.isKnownNever(Mask: fcNan))
2327 return CI->getArgOperand(i: 1);
2328
2329 break;
2330 }
2331 default:
2332 llvm_unreachable("not a min/max intrinsic");
2333 }
2334
2335 Type *EltTy = CI->getType()->getScalarType();
2336 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2337 Known = KnownFPClass::minMaxLike(LHS: KnownLHS, RHS: KnownRHS, Kind: OpKind, DenormMode: Mode);
2338 Known.knownNot(RuleOut: ~DemandedMask);
2339
2340 return getFPClassConstant(Ty: CI->getType(), Mask: Known.KnownFPClasses,
2341 /*IsCanonicalizing=*/true);
2342}
2343
2344static Value *
2345simplifyDemandedUseFPClassFPTrunc(InstCombinerImpl &IC, Instruction &I,
2346 FastMathFlags FMF, FPClassTest DemandedMask,
2347 KnownFPClass &Known, const SimplifyQuery &SQ,
2348 unsigned Depth) {
2349
2350 FPClassTest SrcDemandedMask = DemandedMask;
2351 if (DemandedMask & fcNan)
2352 SrcDemandedMask |= fcNan;
2353
2354 // Zero results may have been rounded from subnormal or normal sources.
2355 if (DemandedMask & fcNegZero)
2356 SrcDemandedMask |= fcNegSubnormal | fcNegNormal;
2357 if (DemandedMask & fcPosZero)
2358 SrcDemandedMask |= fcPosSubnormal | fcPosNormal;
2359
2360 // Subnormal results may have been normal in the source type
2361 if (DemandedMask & fcNegSubnormal)
2362 SrcDemandedMask |= fcNegNormal;
2363 if (DemandedMask & fcPosSubnormal)
2364 SrcDemandedMask |= fcPosNormal;
2365
2366 if (DemandedMask & fcPosInf)
2367 SrcDemandedMask |= fcPosNormal;
2368 if (DemandedMask & fcNegInf)
2369 SrcDemandedMask |= fcNegNormal;
2370
2371 KnownFPClass KnownSrc;
2372 if (IC.SimplifyDemandedFPClass(I: &I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ,
2373 Depth: Depth + 1))
2374 return &I;
2375
2376 Known = KnownFPClass::fptrunc(KnownSrc);
2377 Known.knownNot(RuleOut: ~DemandedMask);
2378
2379 return simplifyDemandedFPClassResult(FPOp: &I, FMF, DemandedMask, Known,
2380 KnownSrcs: {KnownSrc});
2381}
2382
2383Value *InstCombinerImpl::SimplifyDemandedUseFPClass(Instruction *I,
2384 FPClassTest DemandedMask,
2385 KnownFPClass &Known,
2386 const SimplifyQuery &SQ,
2387 unsigned Depth) {
2388 assert(Depth <= MaxAnalysisRecursionDepth && "Limit Search Depth");
2389 assert(Known == KnownFPClass() && "expected uninitialized state");
2390
2391 Type *VTy = I->getType();
2392
2393 FastMathFlags FMF;
2394 if (auto *FPOp = dyn_cast<FPMathOperator>(Val: I)) {
2395 FMF = FPOp->getFastMathFlags();
2396 DemandedMask = adjustDemandedMaskFromFlags(DemandedMask, FMF);
2397 }
2398
2399 switch (I->getOpcode()) {
2400 case Instruction::FNeg: {
2401 // Special case fneg(fabs(x))
2402
2403 Value *FNegSrc = I->getOperand(i: 0);
2404 Value *FNegFAbsSrc;
2405 if (match(V: FNegSrc, P: m_OneUse(SubPattern: m_FAbs(Op0: m_Value(V&: FNegFAbsSrc))))) {
2406 KnownFPClass KnownSrc;
2407 if (SimplifyDemandedFPClass(I: cast<Instruction>(Val: FNegSrc), Op: 0,
2408 DemandedMask: llvm::unknown_sign(Mask: DemandedMask), Known&: KnownSrc,
2409 Q: SQ, Depth: Depth + 1))
2410 return I;
2411
2412 FastMathFlags FabsFMF = cast<FPMathOperator>(Val: FNegSrc)->getFastMathFlags();
2413 FPClassTest ThisDemandedMask =
2414 adjustDemandedMaskFromFlags(DemandedMask, FMF: FabsFMF);
2415
2416 bool IsNSZ = FMF.noSignedZeros() || FabsFMF.noSignedZeros();
2417 if (Value *Simplified = simplifyDemandedFPClassFnegFabs(
2418 Known, Src: FNegFAbsSrc, DemandedMask: ThisDemandedMask, KnownSrc, NSZ: IsNSZ))
2419 return Simplified;
2420
2421 if ((ThisDemandedMask & fcNan) == fcNone)
2422 KnownSrc.knownNot(RuleOut: fcNan);
2423 if ((ThisDemandedMask & fcInf) == fcNone)
2424 KnownSrc.knownNot(RuleOut: fcInf);
2425
2426 // fneg(fabs(x)) => fneg(x)
2427 if (KnownSrc.SignBit == false)
2428 return replaceOperand(I&: *I, OpNum: 0, V: FNegFAbsSrc);
2429
2430 // fneg(fabs(x)) => fneg(x), ignoring -0 if nsz.
2431 if (IsNSZ &&
2432 KnownSrc.isKnownNever(Mask: KnownFPClass::OrderedLessThanZeroMask | fcNan))
2433 return replaceOperand(I&: *I, OpNum: 0, V: FNegFAbsSrc);
2434
2435 break;
2436 }
2437
2438 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: llvm::fneg(Mask: DemandedMask), Known, Q: SQ,
2439 Depth: Depth + 1))
2440 return I;
2441 Known.fneg();
2442 Known.knownNot(RuleOut: ~DemandedMask);
2443 break;
2444 }
2445 case Instruction::FAdd:
2446 case Instruction::FSub: {
2447 KnownFPClass KnownLHS, KnownRHS;
2448
2449 // fadd x, x can be handled more aggressively.
2450 if (I->getOperand(i: 0) == I->getOperand(i: 1) &&
2451 I->getOpcode() == Instruction::FAdd &&
2452 isGuaranteedNotToBeUndef(V: I->getOperand(i: 0), AC: SQ.AC, CtxI: SQ.CxtI, DT: SQ.DT,
2453 Depth: Depth + 1)) {
2454 Type *EltTy = VTy->getScalarType();
2455 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2456
2457 FPClassTest SrcDemandedMask = DemandedMask;
2458 if (DemandedMask & fcNan)
2459 SrcDemandedMask |= fcNan;
2460
2461 // Doubling a subnormal could have resulted in a normal value.
2462 if (DemandedMask & fcPosNormal)
2463 SrcDemandedMask |= fcPosSubnormal;
2464 if (DemandedMask & fcNegNormal)
2465 SrcDemandedMask |= fcNegSubnormal;
2466
2467 // Doubling a subnormal may produce 0 if FTZ/DAZ.
2468 if (Mode != DenormalMode::getIEEE()) {
2469 if (DemandedMask & fcPosZero) {
2470 SrcDemandedMask |= fcPosSubnormal;
2471
2472 if (Mode.inputsMayBePositiveZero() || Mode.outputsMayBePositiveZero())
2473 SrcDemandedMask |= fcNegSubnormal;
2474 }
2475
2476 if (DemandedMask & fcNegZero)
2477 SrcDemandedMask |= fcNegSubnormal;
2478 }
2479
2480 // Doubling a normal could have resulted in an infinity.
2481 if (DemandedMask & fcPosInf)
2482 SrcDemandedMask |= fcPosNormal;
2483 if (DemandedMask & fcNegInf)
2484 SrcDemandedMask |= fcNegNormal;
2485
2486 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Q: SQ,
2487 Depth: Depth + 1))
2488 return I;
2489
2490 Known = KnownFPClass::fadd_self(Src: KnownLHS, Mode);
2491 KnownRHS = KnownLHS;
2492 } else {
2493 FPClassTest SrcDemandedMask = fcFinite;
2494
2495 // inf + (-inf) = nan
2496 if (DemandedMask & fcNan)
2497 SrcDemandedMask |= fcNan | fcInf;
2498
2499 if (DemandedMask & fcInf)
2500 SrcDemandedMask |= fcInf;
2501
2502 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS, Q: SQ,
2503 Depth: Depth + 1) ||
2504 SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Q: SQ,
2505 Depth: Depth + 1))
2506 return I;
2507
2508 Type *EltTy = VTy->getScalarType();
2509 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2510
2511 Known = I->getOpcode() == Instruction::FAdd
2512 ? KnownFPClass::fadd(LHS: KnownLHS, RHS: KnownRHS, Mode)
2513 : KnownFPClass::fsub(LHS: KnownLHS, RHS: KnownRHS, Mode);
2514 }
2515
2516 Known.knownNot(RuleOut: ~DemandedMask);
2517
2518 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2519 /*IsCanonicalizing=*/true))
2520 return SingleVal;
2521
2522 // Propagate known result to simplify edge case checks.
2523 bool ResultNotNan = (DemandedMask & fcNan) == fcNone;
2524
2525 // With nnan: X + {+/-}Inf --> {+/-}Inf
2526 if (ResultNotNan && I->getOpcode() == Instruction::FAdd &&
2527 KnownRHS.isKnownAlways(Mask: fcInf | fcNan) && KnownLHS.isKnownNever(Mask: fcNan))
2528 return I->getOperand(i: 1);
2529
2530 // With nnan: {+/-}Inf + X --> {+/-}Inf
2531 // With nnan: {+/-}Inf - X --> {+/-}Inf
2532 if (ResultNotNan && KnownLHS.isKnownAlways(Mask: fcInf | fcNan) &&
2533 KnownRHS.isKnownNever(Mask: fcNan))
2534 return I->getOperand(i: 0);
2535
2536 FastMathFlags InferredFMF = inferFastMathValueFlags(
2537 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2538 if (InferredFMF != FMF) {
2539 I->setFastMathFlags(InferredFMF);
2540 return I;
2541 }
2542
2543 return nullptr;
2544 }
2545 case Instruction::FMul: {
2546 KnownFPClass KnownLHS, KnownRHS;
2547
2548 Value *X = I->getOperand(i: 0);
2549 Value *Y = I->getOperand(i: 1);
2550
2551 FPClassTest SrcDemandedMask =
2552 DemandedMask & (fcNan | fcZero | fcSubnormal | fcNormal);
2553
2554 if (DemandedMask & fcInf) {
2555 // mul x, inf = inf
2556 // mul large_x, large_y = inf
2557 SrcDemandedMask |= fcSubnormal | fcNormal | fcInf;
2558 }
2559
2560 if (DemandedMask & fcNan) {
2561 // mul +/-inf, 0 => nan
2562 SrcDemandedMask |= fcZero | fcInf | fcNan;
2563
2564 // TODO: Mode check
2565 // mul +/-inf, sub => nan if daz
2566 SrcDemandedMask |= fcSubnormal;
2567 }
2568
2569 // mul normal, subnormal = normal
2570 // Normal inputs may result in underflow.
2571 if (DemandedMask & (fcNormal | fcSubnormal))
2572 SrcDemandedMask |= fcNormal | fcSubnormal;
2573
2574 if (DemandedMask & fcZero)
2575 SrcDemandedMask |= fcNormal | fcSubnormal;
2576
2577 if (X == Y &&
2578 isGuaranteedNotToBeUndef(V: X, AC: SQ.AC, CtxI: SQ.CxtI, DT: SQ.DT, Depth: Depth + 1)) {
2579 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Q: SQ,
2580 Depth: Depth + 1))
2581 return I;
2582 Type *EltTy = VTy->getScalarType();
2583
2584 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2585 Known = KnownFPClass::square(Src: KnownLHS, Mode);
2586 Known.knownNot(RuleOut: ~DemandedMask);
2587
2588 if (Constant *Folded = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2589 /*IsCanonicalizing=*/true))
2590 return Folded;
2591
2592 if (Known.isKnownAlways(Mask: fcPosZero | fcPosInf | fcNan) &&
2593 KnownLHS.isKnownNever(Mask: fcSubnormal | fcNormal)) {
2594 // We can skip the fabs if the source was already known positive.
2595 if (KnownLHS.isKnownAlways(Mask: fcPositive))
2596 return X;
2597
2598 // => fabs(x), in case this was a -inf or -0.
2599 // Note: Dropping canonicalize.
2600 IRBuilderBase::InsertPointGuard Guard(Builder);
2601 Builder.SetInsertPoint(I);
2602 Value *Fabs = Builder.CreateFAbs(V: X, FMFSource: FMF);
2603 Fabs->takeName(V: I);
2604 return Fabs;
2605 }
2606
2607 return nullptr;
2608 }
2609
2610 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS, Q: SQ,
2611 Depth: Depth + 1) ||
2612 SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Q: SQ, Depth: Depth + 1))
2613 return I;
2614
2615 if (FMF.noInfs()) {
2616 // Flag implies inputs cannot be infinity.
2617 KnownLHS.knownNot(RuleOut: fcInf);
2618 KnownRHS.knownNot(RuleOut: fcInf);
2619 }
2620
2621 bool NonNanResult = (DemandedMask & fcNan) == fcNone;
2622
2623 // With no-nans/no-infs:
2624 // X * 0.0 --> copysign(0.0, X)
2625 // X * -0.0 --> copysign(0.0, -X)
2626 if ((NonNanResult || KnownLHS.isKnownNeverInfOrNaN()) &&
2627 KnownRHS.isKnownAlways(Mask: fcPosZero | fcNan)) {
2628 IRBuilderBase::InsertPointGuard Guard(Builder);
2629 Builder.SetInsertPoint(I);
2630
2631 // => copysign(+0, lhs)
2632 // Note: Dropping canonicalize
2633 Value *Copysign = Builder.CreateCopySign(LHS: Y, RHS: X, FMFSource: FMF);
2634 Copysign->takeName(V: I);
2635 return Copysign;
2636 }
2637
2638 if (KnownLHS.isKnownAlways(Mask: fcPosZero | fcNan) &&
2639 (NonNanResult || KnownRHS.isKnownNeverInfOrNaN())) {
2640 IRBuilderBase::InsertPointGuard Guard(Builder);
2641 Builder.SetInsertPoint(I);
2642
2643 // => copysign(+0, rhs)
2644 // Note: Dropping canonicalize
2645 Value *Copysign = Builder.CreateCopySign(LHS: X, RHS: Y, FMFSource: FMF);
2646 Copysign->takeName(V: I);
2647 return Copysign;
2648 }
2649
2650 if ((NonNanResult || KnownLHS.isKnownNeverInfOrNaN()) &&
2651 KnownRHS.isKnownAlways(Mask: fcNegZero | fcNan)) {
2652 IRBuilderBase::InsertPointGuard Guard(Builder);
2653 Builder.SetInsertPoint(I);
2654
2655 // => copysign(0, fneg(lhs))
2656 // Note: Dropping canonicalize
2657 Value *Copysign =
2658 Builder.CreateCopySign(LHS: Y, RHS: Builder.CreateFNegFMF(V: X, FMFSource: FMF), FMFSource: FMF);
2659 Copysign->takeName(V: I);
2660 return Copysign;
2661 }
2662
2663 if (KnownLHS.isKnownAlways(Mask: fcNegZero | fcNan) &&
2664 (NonNanResult || KnownRHS.isKnownNeverInfOrNaN())) {
2665 IRBuilderBase::InsertPointGuard Guard(Builder);
2666 Builder.SetInsertPoint(I);
2667
2668 // => copysign(+0, fneg(rhs))
2669 // Note: Dropping canonicalize
2670 Value *Copysign =
2671 Builder.CreateCopySign(LHS: X, RHS: Builder.CreateFNegFMF(V: Y, FMFSource: FMF), FMFSource: FMF);
2672 Copysign->takeName(V: I);
2673 return Copysign;
2674 }
2675
2676 Type *EltTy = VTy->getScalarType();
2677 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2678
2679 if (KnownLHS.isKnownAlways(Mask: fcInf | fcNan) &&
2680 (KnownRHS.isKnownNeverNaN() &&
2681 KnownRHS.cannotBeOrderedGreaterEqZero(Mode))) {
2682 IRBuilderBase::InsertPointGuard Guard(Builder);
2683 Builder.SetInsertPoint(I);
2684
2685 // Note: Dropping canonicalize
2686 Value *Neg = Builder.CreateFNegFMF(V: X, FMFSource: FMF);
2687 Neg->takeName(V: I);
2688 return Neg;
2689 }
2690
2691 if (KnownRHS.isKnownAlways(Mask: fcInf | fcNan) &&
2692 (KnownLHS.isKnownNeverNaN() &&
2693 KnownLHS.cannotBeOrderedGreaterEqZero(Mode))) {
2694 IRBuilderBase::InsertPointGuard Guard(Builder);
2695 Builder.SetInsertPoint(I);
2696
2697 // Note: Dropping canonicalize
2698 Value *Neg = Builder.CreateFNegFMF(V: Y, FMFSource: FMF);
2699 Neg->takeName(V: I);
2700 return Neg;
2701 }
2702
2703 Known = KnownFPClass::fmul(LHS: KnownLHS, RHS: KnownRHS, Mode);
2704 Known.knownNot(RuleOut: ~DemandedMask);
2705
2706 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2707 /*IsCanonicalizing=*/true))
2708 return SingleVal;
2709
2710 FastMathFlags InferredFMF = inferFastMathValueFlags(
2711 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2712 if (InferredFMF != FMF) {
2713 I->setFastMathFlags(InferredFMF);
2714 return I;
2715 }
2716
2717 return nullptr;
2718 }
2719 case Instruction::FDiv: {
2720 Value *X = I->getOperand(i: 0);
2721 Value *Y = I->getOperand(i: 1);
2722 if (X == Y &&
2723 isGuaranteedNotToBeUndef(V: X, AC: SQ.AC, CtxI: SQ.CxtI, DT: SQ.DT, Depth: Depth + 1)) {
2724 // If the source is 0, inf or nan, the result is a nan
2725 IRBuilderBase::InsertPointGuard Guard(Builder);
2726 Builder.SetInsertPoint(I);
2727
2728 Value *IsZeroOrNan = Builder.CreateFCmpFMF(
2729 P: FCmpInst::FCMP_UEQ, LHS: I->getOperand(i: 0), RHS: ConstantFP::getZero(Ty: VTy), FMFSource: FMF);
2730
2731 Value *Fabs = Builder.CreateFAbs(V: I->getOperand(i: 0), FMFSource: FMF);
2732 Value *IsInfOrNan = Builder.CreateFCmpFMF(
2733 P: FCmpInst::FCMP_UEQ, LHS: Fabs, RHS: ConstantFP::getInfinity(Ty: VTy), FMFSource: FMF);
2734
2735 Value *IsInfOrZeroOrNan = Builder.CreateOr(LHS: IsInfOrNan, RHS: IsZeroOrNan);
2736
2737 return Builder.CreateSelectFMFWithUnknownProfile(
2738 C: IsInfOrZeroOrNan, True: ConstantFP::getQNaN(Ty: VTy),
2739 False: ConstantFP::get(
2740 Ty: VTy, V: APFloat::getOne(Sem: VTy->getScalarType()->getFltSemantics())),
2741 FMFSource: FMF, DEBUG_TYPE);
2742 }
2743
2744 Type *EltTy = VTy->getScalarType();
2745 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2746
2747 // Every output class could require denormal inputs (except for the
2748 // degenerate case of only-nan results, without DAZ).
2749 FPClassTest SrcDemandedMask = (DemandedMask & fcNan) | fcSubnormal;
2750
2751 // Normal inputs may result in underflow.
2752 // x / x = 1.0 for non0/inf/nan
2753 // -x = +y / -z
2754 // -x = -y / +z
2755 if (DemandedMask & (fcSubnormal | fcNormal))
2756 SrcDemandedMask |= fcNormal;
2757
2758 if (DemandedMask & fcNan) {
2759 // 0 / 0 = nan
2760 // inf / inf = nan
2761
2762 // Subnormal is added in case of DAZ, but this isn't strictly
2763 // necessary. Every other input class implies a possible subnormal source,
2764 // so this only could matter in the degenerate case of only-nan results.
2765 SrcDemandedMask |= fcZero | fcInf | fcNan;
2766 }
2767
2768 // Zero outputs may be the result of underflow.
2769 if (DemandedMask & fcZero)
2770 SrcDemandedMask |= fcNormal | fcSubnormal;
2771
2772 FPClassTest LHSDemandedMask = SrcDemandedMask;
2773 FPClassTest RHSDemandedMask = SrcDemandedMask;
2774
2775 // 0 / inf = 0
2776 if (DemandedMask & fcZero) {
2777 assert((LHSDemandedMask & fcSubnormal) &&
2778 "should not have to worry about daz here");
2779 LHSDemandedMask |= fcZero;
2780 RHSDemandedMask |= fcInf;
2781 }
2782
2783 // x / 0 = inf
2784 // large_normal / small_normal = inf
2785 // inf / 1 = inf
2786 // large_normal / subnormal = inf
2787 if (DemandedMask & fcInf) {
2788 LHSDemandedMask |= fcInf | fcNormal | fcSubnormal;
2789 RHSDemandedMask |= fcZero | fcSubnormal | fcNormal;
2790 }
2791
2792 KnownFPClass KnownLHS, KnownRHS;
2793 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: LHSDemandedMask, Known&: KnownLHS, Q: SQ,
2794 Depth: Depth + 1) ||
2795 SimplifyDemandedFPClass(I, Op: 1, DemandedMask: RHSDemandedMask, Known&: KnownRHS, Q: SQ, Depth: Depth + 1))
2796 return I;
2797
2798 bool ResultNotNan = (DemandedMask & fcNan) == fcNone;
2799 bool ResultNotInf = (DemandedMask & fcInf) == fcNone;
2800
2801 // Replacing 0/x with a zero is only valid when the divisor can't be
2802 // (logical) zero, since 0/0 is NaN -- unless NaN results aren't demanded. A
2803 // subnormal divisor can flush to zero under a flushing denormal mode.
2804 bool CanIgnoreZeroByZeroNan =
2805 ResultNotNan || KnownRHS.isKnownNeverLogicalZero(Mode);
2806
2807 // nsz [+-]0 / x -> 0
2808 if (FMF.noSignedZeros() && KnownLHS.isKnownAlways(Mask: fcZero) &&
2809 KnownRHS.isKnownNeverNaN() && CanIgnoreZeroByZeroNan)
2810 return ConstantFP::getZero(Ty: VTy);
2811
2812 if (KnownLHS.isKnownAlways(Mask: fcPosZero) && KnownRHS.isKnownNeverNaN() &&
2813 CanIgnoreZeroByZeroNan) {
2814 IRBuilderBase::InsertPointGuard Guard(Builder);
2815 Builder.SetInsertPoint(I);
2816
2817 // nnan +0 / x -> copysign(0, rhs)
2818 // TODO: -0 / x => copysign(0, fneg(rhs))
2819 Value *Copysign = Builder.CreateCopySign(LHS: X, RHS: Y, FMFSource: FMF);
2820 Copysign->takeName(V: I);
2821 return Copysign;
2822 }
2823
2824 if (!ResultNotInf &&
2825 ((ResultNotNan || (KnownLHS.isKnownNeverNaN() &&
2826 KnownLHS.isKnownNeverLogicalZero(Mode))) &&
2827 (KnownRHS.isKnownAlways(Mask: fcPosZero) ||
2828 (FMF.noSignedZeros() && KnownRHS.isKnownAlways(Mask: fcZero))))) {
2829 IRBuilderBase::InsertPointGuard Guard(Builder);
2830 Builder.SetInsertPoint(I);
2831
2832 // nnan x / 0 => copysign(inf, x);
2833 // nnan nsz x / -0 => copysign(inf, x);
2834 Value *Copysign =
2835 Builder.CreateCopySign(LHS: ConstantFP::getInfinity(Ty: VTy), RHS: X, FMFSource: FMF);
2836 Copysign->takeName(V: I);
2837 return Copysign;
2838 }
2839
2840 // nnan ninf X / [-]0.0 -> poison
2841 if (ResultNotNan && ResultNotInf && KnownRHS.isKnownAlways(Mask: fcZero))
2842 return PoisonValue::get(T: VTy);
2843
2844 Known = KnownFPClass::fdiv(LHS: KnownLHS, RHS: KnownRHS, Mode);
2845 Known.knownNot(RuleOut: ~DemandedMask);
2846
2847 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
2848 /*IsCanonicalizing=*/true))
2849 return SingleVal;
2850
2851 FastMathFlags InferredFMF = inferFastMathValueFlags(
2852 FMF, ValidResults: Known.KnownFPClasses, Known: {KnownLHS, KnownRHS});
2853 if (InferredFMF != FMF) {
2854 I->setFastMathFlags(InferredFMF);
2855 return I;
2856 }
2857
2858 return nullptr;
2859 }
2860 case Instruction::FPTrunc:
2861 return simplifyDemandedUseFPClassFPTrunc(IC&: *this, I&: *I, FMF, DemandedMask,
2862 Known, SQ, Depth);
2863 case Instruction::FPExt: {
2864 FPClassTest SrcDemandedMask = DemandedMask;
2865 if (DemandedMask & fcNan)
2866 SrcDemandedMask |= fcNan;
2867
2868 // No subnormal result does not imply not-subnormal in the source type.
2869 if ((DemandedMask & fcNegNormal) != fcNone)
2870 SrcDemandedMask |= fcNegSubnormal;
2871 if ((DemandedMask & fcPosNormal) != fcNone)
2872 SrcDemandedMask |= fcPosSubnormal;
2873
2874 KnownFPClass KnownSrc;
2875 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ, Depth: Depth + 1))
2876 return I;
2877
2878 const fltSemantics &DstTy = VTy->getScalarType()->getFltSemantics();
2879 const fltSemantics &SrcTy =
2880 I->getOperand(i: 0)->getType()->getScalarType()->getFltSemantics();
2881
2882 Known = KnownFPClass::fpext(KnownSrc, DstTy, SrcTy);
2883 Known.knownNot(RuleOut: ~DemandedMask);
2884
2885 return simplifyDemandedFPClassResult(FPOp: I, FMF, DemandedMask, Known,
2886 KnownSrcs: {KnownSrc});
2887 }
2888 case Instruction::Call: {
2889 CallInst *CI = cast<CallInst>(Val: I);
2890 const Intrinsic::ID IID = CI->getIntrinsicID();
2891 switch (IID) {
2892 case Intrinsic::fabs: {
2893 KnownFPClass KnownSrc;
2894 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: llvm::inverse_fabs(Mask: DemandedMask),
2895 Known&: KnownSrc, Q: SQ, Depth: Depth + 1))
2896 return I;
2897
2898 if (Value *Simplified = simplifyDemandedFPClassFabs(
2899 Known, Src: CI->getArgOperand(i: 0), DemandedMask, KnownSrc,
2900 NSZ: FMF.noSignedZeros()))
2901 return Simplified;
2902 break;
2903 }
2904 case Intrinsic::arithmetic_fence:
2905 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known, Q: SQ, Depth: Depth + 1))
2906 return I;
2907 break;
2908 case Intrinsic::copysign: {
2909 // Flip on more potentially demanded classes
2910 const FPClassTest DemandedMaskAnySign = llvm::unknown_sign(Mask: DemandedMask);
2911 KnownFPClass KnownMag;
2912 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: DemandedMaskAnySign, Known&: KnownMag, Q: SQ,
2913 Depth: Depth + 1))
2914 return I;
2915
2916 if ((DemandedMask & fcNegative) == DemandedMask) {
2917 // Roundabout way of replacing with fneg(fabs)
2918 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::get(Ty: VTy, V: -1.0));
2919 return I;
2920 }
2921
2922 if ((DemandedMask & fcPositive) == DemandedMask) {
2923 // Roundabout way of replacing with fabs
2924 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::getZero(Ty: VTy));
2925 return I;
2926 }
2927
2928 if (Value *Simplified = simplifyDemandedFPClassCopysignMag(
2929 MagSrc: CI->getArgOperand(i: 0), DemandedMask, KnownSrc: KnownMag,
2930 NSZ: FMF.noSignedZeros()))
2931 return Simplified;
2932
2933 KnownFPClass KnownSign =
2934 computeKnownFPClass(V: CI->getArgOperand(i: 1), InterestedClasses: fcAllFlags, SQ, Depth: Depth + 1);
2935 if (KnownMag.SignBit && KnownSign.SignBit &&
2936 *KnownMag.SignBit == *KnownSign.SignBit)
2937 return CI->getOperand(i_nocapture: 0);
2938
2939 // TODO: Call argument attribute not considered
2940 // Input implied not-nan from flag.
2941 if (FMF.noNaNs())
2942 KnownSign.knownNot(RuleOut: fcNan);
2943
2944 if (KnownSign.SignBit == false) {
2945 CI->dropUBImplyingAttrsAndMetadata();
2946 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::getZero(Ty: VTy));
2947 return I;
2948 }
2949
2950 if (KnownSign.SignBit == true) {
2951 CI->dropUBImplyingAttrsAndMetadata();
2952 CI->setOperand(i_nocapture: 1, Val_nocapture: ConstantFP::get(Ty: VTy, V: -1.0));
2953 return I;
2954 }
2955
2956 Known = KnownFPClass::copysign(KnownMag, KnownSign);
2957 Known.knownNot(RuleOut: ~DemandedMask);
2958 break;
2959 }
2960 case Intrinsic::fma:
2961 case Intrinsic::fmuladd: {
2962 // We can't do any simplification on the source besides stripping out
2963 // unneeded nans.
2964 FPClassTest SrcDemandedMask = DemandedMask | ~fcNan;
2965 if (DemandedMask & fcNan)
2966 SrcDemandedMask |= fcNan;
2967
2968 KnownFPClass KnownSrc[3];
2969
2970 Type *EltTy = VTy->getScalarType();
2971 if (CI->getArgOperand(i: 0) == CI->getArgOperand(i: 1) &&
2972 isGuaranteedNotToBeUndef(V: CI->getArgOperand(i: 0), AC: SQ.AC, CtxI: SQ.CxtI, DT: SQ.DT,
2973 Depth: Depth + 1)) {
2974 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc[0], Q: SQ,
2975 Depth: Depth + 1) ||
2976 SimplifyDemandedFPClass(I: CI, Op: 2, DemandedMask: SrcDemandedMask, Known&: KnownSrc[2], Q: SQ,
2977 Depth: Depth + 1))
2978 return I;
2979
2980 KnownSrc[1] = KnownSrc[0];
2981 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2982 Known = KnownFPClass::fma_square(Squared: KnownSrc[0], Addend: KnownSrc[2], Mode);
2983 } else {
2984 for (int OpIdx = 0; OpIdx != 3; ++OpIdx) {
2985 if (SimplifyDemandedFPClass(I: CI, Op: OpIdx, DemandedMask: SrcDemandedMask,
2986 Known&: KnownSrc[OpIdx], Q: SQ, Depth: Depth + 1))
2987 return CI;
2988 }
2989
2990 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
2991 Known = KnownFPClass::fma(LHS: KnownSrc[0], RHS: KnownSrc[1], Addend: KnownSrc[2], Mode);
2992 }
2993
2994 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
2995 KnownSrcs: {KnownSrc});
2996 }
2997 case Intrinsic::maximum:
2998 case Intrinsic::minimum:
2999 case Intrinsic::maximumnum:
3000 case Intrinsic::minimumnum:
3001 case Intrinsic::maxnum:
3002 case Intrinsic::minnum: {
3003 const bool PropagateNaN =
3004 IID == Intrinsic::maximum || IID == Intrinsic::minimum;
3005
3006 // We can't tell much based on the demanded result without inspecting the
3007 // operands (e.g., a known-positive result could have been clamped), but
3008 // we can still prune known-nan inputs.
3009 FPClassTest SrcDemandedMask =
3010 PropagateNaN && ((DemandedMask & fcNan) == fcNone)
3011 ? DemandedMask | ~fcNan
3012 : fcAllFlags;
3013
3014 KnownFPClass KnownLHS, KnownRHS;
3015 if (SimplifyDemandedFPClass(I: CI, Op: 1, DemandedMask: SrcDemandedMask, Known&: KnownRHS, Q: SQ,
3016 Depth: Depth + 1) ||
3017 SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownLHS, Q: SQ,
3018 Depth: Depth + 1))
3019 return I;
3020
3021 Value *Simplified =
3022 simplifyDemandedFPClassMinMax(Known, IID, CI, DemandedMask, KnownLHS,
3023 KnownRHS, F, NSZ: FMF.noSignedZeros());
3024 if (Simplified)
3025 return Simplified;
3026
3027 auto *FPOp = cast<FPMathOperator>(Val: CI);
3028
3029 FPClassTest ValidResults = DemandedMask & Known.KnownFPClasses;
3030 FastMathFlags InferredFMF = FMF;
3031
3032 if (!FMF.noSignedZeros()) {
3033 // Add NSZ flag if we know the result will not be sensitive to the sign
3034 // of 0.
3035 FPClassTest ZeroMask = fcZero;
3036
3037 Type *EltTy = VTy->getScalarType();
3038 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3039 if (Mode != DenormalMode::getIEEE())
3040 ZeroMask |= fcSubnormal;
3041
3042 bool ResultNotLogical0 = (ValidResults & ZeroMask) == fcNone;
3043 if (ResultNotLogical0 || ((KnownLHS.isKnownNeverLogicalNegZero(Mode) ||
3044 KnownRHS.isKnownNeverLogicalPosZero(Mode)) &&
3045 (KnownLHS.isKnownNeverLogicalPosZero(Mode) ||
3046 KnownRHS.isKnownNeverLogicalNegZero(Mode))))
3047 InferredFMF.setNoSignedZeros(true);
3048 }
3049
3050 if (!FMF.noNaNs() &&
3051 ((PropagateNaN && (ValidResults & fcNan) == fcNone) ||
3052 (KnownLHS.isKnownNeverNaN() && KnownRHS.isKnownNeverNaN()))) {
3053 CI->dropUBImplyingAttrsAndMetadata();
3054 InferredFMF.setNoNaNs(true);
3055 }
3056
3057 if (InferredFMF != FMF) {
3058 CI->setFastMathFlags(InferredFMF);
3059 return FPOp;
3060 }
3061
3062 return nullptr;
3063 }
3064 case Intrinsic::exp:
3065 case Intrinsic::exp2:
3066 case Intrinsic::exp10: {
3067 if ((DemandedMask & fcPositive) == fcNone) {
3068 // Only returns positive values or nans.
3069 if ((DemandedMask & fcNan) == fcNone)
3070 return PoisonValue::get(T: VTy);
3071
3072 // Only need nan propagation.
3073 if ((DemandedMask & ~fcNan) == fcNone)
3074 return ConstantFP::getQNaN(Ty: VTy);
3075
3076 return CI->getArgOperand(i: 0);
3077 }
3078
3079 FPClassTest SrcDemandedMask = DemandedMask & fcNan;
3080 if (DemandedMask & fcNan)
3081 SrcDemandedMask |= fcNan;
3082
3083 if (DemandedMask & fcZero) {
3084 // exp(-infinity) = 0
3085 SrcDemandedMask |= fcNegInf;
3086
3087 // exp(-largest_normal) = 0
3088 //
3089 // Negative numbers of sufficiently large magnitude underflow to 0. No
3090 // subnormal input has a 0 result.
3091 SrcDemandedMask |= fcNegNormal;
3092 }
3093
3094 if (DemandedMask & fcPosSubnormal) {
3095 // Negative numbers of sufficiently large magnitude underflow to 0. No
3096 // subnormal input has a 0 result.
3097 SrcDemandedMask |= fcNegNormal;
3098 }
3099
3100 if (DemandedMask & fcPosNormal) {
3101 // exp(0) = 1
3102 // exp(+/- smallest_normal) = 1
3103 // exp(+/- largest_denormal) = 1
3104 // exp(+/- smallest_denormal) = 1
3105 // exp(-1) = pos normal
3106 SrcDemandedMask |= fcNormal | fcSubnormal | fcZero;
3107 }
3108
3109 // exp(inf), exp(largest_normal) = inf
3110 if (DemandedMask & fcPosInf)
3111 SrcDemandedMask |= fcPosInf | fcPosNormal;
3112
3113 KnownFPClass KnownSrc;
3114
3115 // TODO: This could really make use of KnownFPClass of specific value
3116 // range, (i.e., close enough to 1)
3117 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ,
3118 Depth: Depth + 1))
3119 return I;
3120
3121 // exp(+/-0) = 1
3122 if (KnownSrc.isKnownAlways(Mask: fcZero))
3123 return ConstantFP::get(Ty: VTy, V: 1.0);
3124
3125 // Only perform nan propagation.
3126 // Note: Dropping canonicalize / quiet of signaling nan.
3127 if (KnownSrc.isKnownAlways(Mask: fcNan))
3128 return CI->getArgOperand(i: 0);
3129
3130 // exp(0 | nan) => x == 0.0 ? 1.0 : x
3131 if (KnownSrc.isKnownAlways(Mask: fcZero | fcNan)) {
3132 IRBuilderBase::InsertPointGuard Guard(Builder);
3133 Builder.SetInsertPoint(CI);
3134
3135 // fadd +/-0, 1.0 => 1.0
3136 // fadd nan, 1.0 => nan
3137 return Builder.CreateFAddFMF(L: CI->getArgOperand(i: 0),
3138 R: ConstantFP::get(Ty: VTy, V: 1.0), FMFSource: FMF);
3139 }
3140
3141 if (KnownSrc.isKnownAlways(Mask: fcInf | fcNan)) {
3142 // exp(-inf) = 0
3143 // exp(+inf) = +inf
3144 IRBuilderBase::InsertPointGuard Guard(Builder);
3145 Builder.SetInsertPoint(CI);
3146
3147 // Note: Dropping canonicalize / quiet of signaling nan.
3148 Value *X = CI->getArgOperand(i: 0);
3149 Value *IsPosInfOrNan = Builder.CreateFCmpFMF(
3150 P: FCmpInst::FCMP_UEQ, LHS: X, RHS: ConstantFP::getInfinity(Ty: VTy), FMFSource: FMF);
3151 // We do not know whether an infinity or a NaN is more likely here,
3152 // so mark the branch weights as unkown.
3153 Value *ZeroOrInf = Builder.CreateSelectFMFWithUnknownProfile(
3154 C: IsPosInfOrNan, True: X, False: ConstantFP::getZero(Ty: VTy), FMFSource: FMF, DEBUG_TYPE);
3155 return ZeroOrInf;
3156 }
3157
3158 Known = KnownFPClass::exp(Src: KnownSrc);
3159 Known.knownNot(RuleOut: ~DemandedMask);
3160
3161 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3162 KnownSrcs: KnownSrc);
3163 }
3164 case Intrinsic::log:
3165 case Intrinsic::log2:
3166 case Intrinsic::log10: {
3167 FPClassTest DemandedSrcMask = DemandedMask & (fcNan | fcPosInf);
3168 if (DemandedMask & fcNan)
3169 DemandedSrcMask |= fcNan;
3170
3171 Type *EltTy = VTy->getScalarType();
3172 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3173
3174 // log(x < 0) = nan
3175 if (DemandedMask & fcNan)
3176 DemandedSrcMask |= (fcNegative & ~fcNegZero);
3177
3178 // log(0) = -inf
3179 if (DemandedMask & fcNegInf) {
3180 DemandedSrcMask |= fcZero;
3181
3182 // No value produces subnormal result.
3183 if (Mode.inputsMayBeZero())
3184 DemandedSrcMask |= fcSubnormal;
3185 }
3186
3187 if (DemandedMask & fcNormal)
3188 DemandedSrcMask |= fcNormal | fcSubnormal;
3189
3190 // log(1) = 0
3191 if (DemandedMask & fcZero)
3192 DemandedSrcMask |= fcPosNormal;
3193
3194 KnownFPClass KnownSrc;
3195 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Q: SQ,
3196 Depth: Depth + 1))
3197 return I;
3198
3199 Known = KnownFPClass::log(Src: KnownSrc, Mode);
3200 Known.knownNot(RuleOut: ~DemandedMask);
3201
3202 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3203 KnownSrcs: KnownSrc);
3204 }
3205 case Intrinsic::sqrt: {
3206 FPClassTest DemandedSrcMask =
3207 DemandedMask & (fcNegZero | fcPositive | fcNan);
3208
3209 if (DemandedMask & fcNan)
3210 DemandedSrcMask |= fcNan | (fcNegative & ~fcNegZero);
3211
3212 // sqrt(max_subnormal) is a normal value
3213 if (DemandedMask & fcPosNormal)
3214 DemandedSrcMask |= fcPosSubnormal;
3215
3216 KnownFPClass KnownSrc;
3217 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Q: SQ,
3218 Depth: Depth + 1))
3219 return I;
3220
3221 // Infer the source cannot be negative if the result cannot be nan.
3222 if ((DemandedMask & fcNan) == fcNone)
3223 KnownSrc.knownNot(RuleOut: (fcNegative & ~fcNegZero) | fcNan);
3224
3225 // Infer the source cannot be +inf if the result is not +nf
3226 if ((DemandedMask & fcPosInf) == fcNone)
3227 KnownSrc.knownNot(RuleOut: fcPosInf);
3228
3229 Type *EltTy = VTy->getScalarType();
3230 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3231
3232 // sqrt(-x) = nan, but be careful of negative subnormals flushed to 0.
3233 if (KnownSrc.isKnownNever(Mask: fcPositive) &&
3234 KnownSrc.isKnownNeverLogicalZero(Mode))
3235 return ConstantFP::getQNaN(Ty: VTy);
3236
3237 Known = KnownFPClass::sqrt(Src: KnownSrc, Mode);
3238 Known.knownNot(RuleOut: ~DemandedMask);
3239
3240 if (Known.KnownFPClasses == fcZero) {
3241 if (FMF.noSignedZeros())
3242 return ConstantFP::getZero(Ty: VTy);
3243 IRBuilderBase::InsertPointGuard Guard(Builder);
3244 Builder.SetInsertPoint(CI);
3245
3246 Value *Copysign = Builder.CreateCopySign(LHS: ConstantFP::getZero(Ty: VTy),
3247 RHS: CI->getArgOperand(i: 0), FMFSource: FMF);
3248 Copysign->takeName(V: CI);
3249 return Copysign;
3250 }
3251
3252 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3253 KnownSrcs: {KnownSrc});
3254 }
3255 case Intrinsic::ldexp: {
3256 FPClassTest SrcDemandedMask = DemandedMask & fcInf;
3257 if (DemandedMask & fcNan)
3258 SrcDemandedMask |= fcNan;
3259
3260 if (DemandedMask & fcPosInf)
3261 SrcDemandedMask |= fcPosNormal | fcPosSubnormal;
3262 if (DemandedMask & fcNegInf)
3263 SrcDemandedMask |= fcNegNormal | fcNegSubnormal;
3264
3265 if (DemandedMask & (fcPosNormal | fcPosSubnormal))
3266 SrcDemandedMask |= fcPosNormal | fcPosSubnormal;
3267 if (DemandedMask & (fcNegNormal | fcNegSubnormal))
3268 SrcDemandedMask |= fcNegNormal | fcNegSubnormal;
3269
3270 if (DemandedMask & fcPosZero)
3271 SrcDemandedMask |= fcPosFinite;
3272 if (DemandedMask & fcNegZero)
3273 SrcDemandedMask |= fcNegFinite;
3274
3275 KnownFPClass KnownSrc;
3276 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ,
3277 Depth: Depth + 1))
3278 return CI;
3279
3280 Type *EltTy = VTy->getScalarType();
3281 const fltSemantics &FltSem = EltTy->getFltSemantics();
3282 DenormalMode Mode = F.getDenormalMode(FPType: FltSem);
3283
3284 KnownBits KnownExpBits =
3285 ::computeKnownBits(V: CI->getArgOperand(i: 1), Q: SQ, Depth: Depth + 1);
3286
3287 Known = KnownFPClass::ldexp(Src: KnownSrc, ExpBits: KnownExpBits, Flt: FltSem, Mode);
3288 Known.knownNot(RuleOut: ~DemandedMask);
3289
3290 return simplifyDemandedFPClassResult(FPOp: CI, FMF, DemandedMask, Known,
3291 KnownSrcs: {KnownSrc});
3292 }
3293 case Intrinsic::trunc:
3294 case Intrinsic::floor:
3295 case Intrinsic::ceil:
3296 case Intrinsic::rint:
3297 case Intrinsic::nearbyint:
3298 case Intrinsic::round:
3299 case Intrinsic::roundeven: {
3300 FPClassTest DemandedSrcMask = DemandedMask;
3301 if (DemandedMask & fcNan)
3302 DemandedSrcMask |= fcNan;
3303
3304 // Zero results imply valid subnormal sources.
3305 if (DemandedMask & fcNegZero)
3306 DemandedSrcMask |= fcNegSubnormal | fcNegNormal;
3307
3308 if (DemandedMask & fcPosZero)
3309 DemandedSrcMask |= fcPosSubnormal | fcPosNormal;
3310
3311 KnownFPClass KnownSrc;
3312 if (SimplifyDemandedFPClass(I: CI, Op: 0, DemandedMask: DemandedSrcMask, Known&: KnownSrc, Q: SQ,
3313 Depth: Depth + 1))
3314 return I;
3315
3316 // Note: Possibly dropping snan quiet.
3317 if (KnownSrc.isKnownAlways(Mask: fcInf | fcNan | fcZero))
3318 return CI->getArgOperand(i: 0);
3319
3320 bool IsRoundNearestOrTrunc =
3321 IID == Intrinsic::round || IID == Intrinsic::roundeven ||
3322 IID == Intrinsic::nearbyint || IID == Intrinsic::rint ||
3323 IID == Intrinsic::trunc;
3324
3325 // Ignore denormals-as-zero, as canonicalization is not mandated.
3326 if ((IID == Intrinsic::floor || IsRoundNearestOrTrunc) &&
3327 KnownSrc.isKnownAlways(Mask: fcPosZero | fcPosSubnormal))
3328 return ConstantFP::getZero(Ty: VTy);
3329
3330 if ((IID == Intrinsic::ceil || IsRoundNearestOrTrunc) &&
3331 KnownSrc.isKnownAlways(Mask: fcNegZero | fcNegSubnormal))
3332 return ConstantFP::getZero(Ty: VTy, Negative: true);
3333
3334 if (IID == Intrinsic::floor && KnownSrc.isKnownAlways(Mask: fcNegSubnormal))
3335 return ConstantFP::get(Ty: VTy, V: -1.0);
3336
3337 if (IID == Intrinsic::ceil && KnownSrc.isKnownAlways(Mask: fcPosSubnormal))
3338 return ConstantFP::get(Ty: VTy, V: 1.0);
3339
3340 Known = KnownFPClass::roundToIntegral(
3341 Src: KnownSrc, IsTrunc: IID == Intrinsic::trunc,
3342 IsMultiUnitFPType: VTy->getScalarType()->isMultiUnitFPType());
3343
3344 Known.knownNot(RuleOut: ~DemandedMask);
3345
3346 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
3347 /*IsCanonicalizing=*/true))
3348 return SingleVal;
3349
3350 if ((IID == Intrinsic::trunc || IsRoundNearestOrTrunc) &&
3351 KnownSrc.isKnownAlways(Mask: fcZero | fcSubnormal)) {
3352 IRBuilderBase::InsertPointGuard Guard(Builder);
3353 Builder.SetInsertPoint(CI);
3354
3355 Value *Copysign = Builder.CreateCopySign(LHS: ConstantFP::getZero(Ty: VTy),
3356 RHS: CI->getArgOperand(i: 0));
3357 Copysign->takeName(V: CI);
3358 return Copysign;
3359 }
3360
3361 FastMathFlags InferredFMF =
3362 inferFastMathValueFlags(FMF, ValidResults: Known.KnownFPClasses, Known: KnownSrc);
3363 if (InferredFMF != FMF) {
3364 CI->dropUBImplyingAttrsAndMetadata();
3365 CI->setFastMathFlags(InferredFMF);
3366 return CI;
3367 }
3368
3369 return nullptr;
3370 }
3371 case Intrinsic::fptrunc_round:
3372 return simplifyDemandedUseFPClassFPTrunc(IC&: *this, I&: *CI, FMF, DemandedMask,
3373 Known, SQ, Depth);
3374 case Intrinsic::canonicalize: {
3375 Type *EltTy = VTy->getScalarType();
3376
3377 // TODO: This could have more refined support for PositiveZero denormal
3378 // mode.
3379 if (EltTy->isIEEELikeFPTy()) {
3380 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3381
3382 FPClassTest SrcDemandedMask = DemandedMask;
3383
3384 // A demanded quiet nan result may have come from a signaling nan, so we
3385 // need to expand the demanded mask.
3386 if ((DemandedMask & fcQNan) != fcNone)
3387 SrcDemandedMask |= fcSNan;
3388
3389 if (Mode != DenormalMode::getIEEE()) {
3390 // Any zero results may have come from flushed denormals.
3391 if (DemandedMask & fcPosZero)
3392 SrcDemandedMask |= fcPosSubnormal;
3393 if (DemandedMask & fcNegZero)
3394 SrcDemandedMask |= fcNegSubnormal;
3395 }
3396
3397 if (Mode == DenormalMode::getPreserveSign()) {
3398 // If a denormal input will be flushed, and we don't need zeros, we
3399 // don't need denormals either.
3400 if ((DemandedMask & fcPosZero) == fcNone)
3401 SrcDemandedMask &= ~fcPosSubnormal;
3402
3403 if ((DemandedMask & fcNegZero) == fcNone)
3404 SrcDemandedMask &= ~fcNegSubnormal;
3405 }
3406
3407 KnownFPClass KnownSrc;
3408
3409 // Simplify upstream operations before trying to simplify this call.
3410 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ,
3411 Depth: Depth + 1))
3412 return I;
3413
3414 // Perform the canonicalization to see if this folded to a constant.
3415 Known = KnownFPClass::canonicalize(Src: KnownSrc, DenormMode: Mode);
3416 Known.knownNot(RuleOut: ~DemandedMask);
3417
3418 if (Constant *SingleVal = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses))
3419 return SingleVal;
3420
3421 // For IEEE handling, there is only a bit change for nan inputs, so we
3422 // can drop it if we do not demand nan results or we know the input
3423 // isn't a nan.
3424 // Otherwise, we also need to avoid denormal inputs to drop the
3425 // canonicalize.
3426 if (KnownSrc.isKnownNeverNaN() && (Mode == DenormalMode::getIEEE() ||
3427 KnownSrc.isKnownNeverSubnormal()))
3428 return CI->getArgOperand(i: 0);
3429
3430 FastMathFlags InferredFMF =
3431 inferFastMathValueFlags(FMF, ValidResults: Known.KnownFPClasses, Known: KnownSrc);
3432 if (InferredFMF != FMF) {
3433 CI->dropUBImplyingAttrsAndMetadata();
3434 CI->setFastMathFlags(InferredFMF);
3435 return CI;
3436 }
3437
3438 return nullptr;
3439 }
3440
3441 [[fallthrough]];
3442 }
3443 default:
3444 Known = computeKnownFPClass(V: I, InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3445 Known.knownNot(RuleOut: ~DemandedMask);
3446 break;
3447 }
3448
3449 break;
3450 }
3451 case Instruction::Select: {
3452 KnownFPClass KnownLHS, KnownRHS;
3453 if (SimplifyDemandedFPClass(I, Op: 2, DemandedMask, Known&: KnownRHS, Q: SQ, Depth: Depth + 1) ||
3454 SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownLHS, Q: SQ, Depth: Depth + 1))
3455 return I;
3456
3457 if (KnownLHS.isKnownNever(Mask: DemandedMask))
3458 return I->getOperand(i: 2);
3459 if (KnownRHS.isKnownNever(Mask: DemandedMask))
3460 return I->getOperand(i: 1);
3461
3462 adjustKnownFPClassForSelectArm(Known&: KnownLHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
3463 /*Invert=*/false, Q: SQ, Depth);
3464 adjustKnownFPClassForSelectArm(Known&: KnownRHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
3465 /*Invert=*/true, Q: SQ, Depth);
3466 Known = KnownLHS.intersectWith(RHS: KnownRHS);
3467 Known.knownNot(RuleOut: ~DemandedMask);
3468 break;
3469 }
3470 case Instruction::ExtractElement: {
3471 // TODO: Handle demanded element mask
3472 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known, Q: SQ, Depth: Depth + 1))
3473 return I;
3474 Known.knownNot(RuleOut: ~DemandedMask);
3475 break;
3476 }
3477 case Instruction::InsertElement: {
3478 KnownFPClass KnownInserted, KnownVec;
3479 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownInserted, Q: SQ,
3480 Depth: Depth + 1) ||
3481 SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownVec, Q: SQ, Depth: Depth + 1))
3482 return I;
3483
3484 // TODO: Use demanded elements logic from computeKnownFPClass
3485 Known = KnownVec | KnownInserted;
3486 Known.knownNot(RuleOut: ~DemandedMask);
3487 break;
3488 }
3489 case Instruction::ShuffleVector: {
3490 KnownFPClass KnownLHS, KnownRHS;
3491 if (SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownRHS, Q: SQ, Depth: Depth + 1) ||
3492 SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownLHS, Q: SQ, Depth: Depth + 1))
3493 return I;
3494
3495 // TODO: This is overly conservative and should consider demanded elements,
3496 // and splats.
3497 Known = KnownLHS | KnownRHS;
3498 Known.knownNot(RuleOut: ~DemandedMask);
3499 break;
3500 }
3501 case Instruction::InsertValue: {
3502 KnownFPClass KnownAgg, KnownElt;
3503 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownAgg, Q: SQ, Depth: Depth + 1) ||
3504 SimplifyDemandedFPClass(I, Op: 1, DemandedMask, Known&: KnownElt, Q: SQ, Depth: Depth + 1))
3505 return I;
3506
3507 Known = KnownAgg | KnownElt;
3508 break;
3509 }
3510 case Instruction::ExtractValue: {
3511 Value *ExtractSrc;
3512 if (match(V: I, P: m_ExtractValue<0>(V: m_OneUse(SubPattern: m_Value(V&: ExtractSrc))))) {
3513 if (auto *II = dyn_cast<IntrinsicInst>(Val: ExtractSrc)) {
3514 const Intrinsic::ID IID = II->getIntrinsicID();
3515 switch (IID) {
3516 case Intrinsic::frexp: {
3517 FPClassTest SrcDemandedMask = fcNone;
3518 if (DemandedMask & fcNan)
3519 SrcDemandedMask |= fcNan;
3520 if (DemandedMask & fcNegFinite)
3521 SrcDemandedMask |= fcNegFinite;
3522 if (DemandedMask & fcPosFinite)
3523 SrcDemandedMask |= fcPosFinite;
3524 if (DemandedMask & fcPosInf)
3525 SrcDemandedMask |= fcPosInf;
3526 if (DemandedMask & fcNegInf)
3527 SrcDemandedMask |= fcNegInf;
3528
3529 KnownFPClass KnownSrc;
3530 if (SimplifyDemandedFPClass(I: II, Op: 0, DemandedMask: SrcDemandedMask, Known&: KnownSrc, Q: SQ,
3531 Depth: Depth + 1))
3532 return I;
3533
3534 Type *EltTy = VTy->getScalarType();
3535 DenormalMode Mode = F.getDenormalMode(FPType: EltTy->getFltSemantics());
3536
3537 Known = KnownFPClass::frexp_mant(Src: KnownSrc, Mode);
3538 Known.KnownFPClasses &= DemandedMask;
3539
3540 if (Constant *SingleVal =
3541 getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses,
3542 /*IsCanonicalizing=*/true))
3543 return SingleVal;
3544
3545 if (Known.isKnownAlways(Mask: fcInf | fcNan))
3546 return II->getArgOperand(i: 0);
3547
3548 return nullptr;
3549 }
3550 default:
3551 break;
3552 }
3553 }
3554 }
3555
3556 KnownFPClass KnownSrc;
3557 if (SimplifyDemandedFPClass(I, Op: 0, DemandedMask, Known&: KnownSrc, Q: SQ, Depth: Depth + 1))
3558 return I;
3559 Known = KnownSrc;
3560 break;
3561 }
3562 case Instruction::PHI: {
3563 const unsigned PhiRecursionLimit = MaxAnalysisRecursionDepth - 2;
3564 if (Depth >= PhiRecursionLimit)
3565 break;
3566
3567 PHINode *P = cast<PHINode>(Val: I);
3568 SimplifyQuery ContextSQ = SQ.getWithoutCondContext();
3569
3570 bool First = true;
3571 bool Changed = false;
3572 for (unsigned I = 0, E = P->getNumIncomingValues(); I != E; ++I) {
3573 // TODO: Better support for self recursive phi
3574 BasicBlock *PredBB = P->getIncomingBlock(i: I);
3575 const Instruction *CtxI = PredBB->getTerminator();
3576
3577 // Attempt to simplify all incoming edges at a time. If we simplify one
3578 // incoming edge, the phi may fold away, losing information on a later
3579 // visit.
3580 KnownFPClass KnownSrc;
3581 if (SimplifyDemandedFPClass(
3582 I: P, Op: P->getOperandNumForIncomingValue(i: I), DemandedMask, Known&: KnownSrc,
3583 Q: ContextSQ.getWithInstruction(I: CtxI), Depth: Depth + 1)) {
3584 // Fixup the other block references to the simplified value.
3585 P->setIncomingValueForBlock(BB: PredBB, V: P->getIncomingValue(i: I));
3586 Changed = true;
3587 }
3588
3589 if (First) {
3590 Known = KnownSrc;
3591 First = false;
3592 } else {
3593 Known |= KnownSrc;
3594 }
3595 }
3596
3597 if (Changed)
3598 return P;
3599
3600 Known.knownNot(RuleOut: ~DemandedMask);
3601 break;
3602 }
3603 default:
3604 Known = computeKnownFPClass(V: I, InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3605 Known.knownNot(RuleOut: ~DemandedMask);
3606 break;
3607 }
3608
3609 return getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses);
3610}
3611
3612/// Helper routine of SimplifyDemandedUseFPClass. It computes Known
3613/// floating-point classes. It also tries to handle simplifications that can be
3614/// done based on DemandedMask, but without modifying the Instruction.
3615Value *InstCombinerImpl::SimplifyMultipleUseDemandedFPClass(
3616 Instruction *I, FPClassTest DemandedMask, KnownFPClass &Known,
3617 const SimplifyQuery &SQ, unsigned Depth) {
3618 FastMathFlags FMF;
3619 if (auto *FPOp = dyn_cast<FPMathOperator>(Val: I)) {
3620 FMF = FPOp->getFastMathFlags();
3621 DemandedMask = adjustDemandedMaskFromFlags(DemandedMask, FMF);
3622 }
3623
3624 switch (I->getOpcode()) {
3625 case Instruction::Select: {
3626 // TODO: Can we infer which side it came from based on adjusted result
3627 // class?
3628 KnownFPClass KnownRHS =
3629 computeKnownFPClass(V: I->getOperand(i: 2), InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3630 if (KnownRHS.isKnownNever(Mask: DemandedMask))
3631 return I->getOperand(i: 1);
3632
3633 KnownFPClass KnownLHS =
3634 computeKnownFPClass(V: I->getOperand(i: 1), InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3635 if (KnownLHS.isKnownNever(Mask: DemandedMask))
3636 return I->getOperand(i: 2);
3637
3638 adjustKnownFPClassForSelectArm(Known&: KnownLHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 1),
3639 /*Invert=*/false, Q: SQ, Depth);
3640 adjustKnownFPClassForSelectArm(Known&: KnownRHS, Cond: I->getOperand(i: 0), Arm: I->getOperand(i: 2),
3641 /*Invert=*/true, Q: SQ, Depth);
3642 Known = KnownLHS.intersectWith(RHS: KnownRHS);
3643 Known.knownNot(RuleOut: ~DemandedMask);
3644 break;
3645 }
3646 case Instruction::FNeg: {
3647 // Special case fneg(fabs(x))
3648 Value *Src;
3649
3650 Value *FNegSrc = I->getOperand(i: 0);
3651 if (!match(V: FNegSrc, P: m_FAbs(Op0: m_Value(V&: Src)))) {
3652 Known = computeKnownFPClass(V: I, InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3653 break;
3654 }
3655
3656 KnownFPClass KnownSrc = computeKnownFPClass(V: Src, InterestedClasses: fcAllFlags, SQ, Depth: Depth + 1);
3657
3658 FastMathFlags FabsFMF = cast<FPMathOperator>(Val: FNegSrc)->getFastMathFlags();
3659 FPClassTest ThisDemandedMask =
3660 adjustDemandedMaskFromFlags(DemandedMask, FMF: FabsFMF);
3661
3662 // We cannot apply the NSZ logic with multiple uses. We can apply it if the
3663 // inner fabs has it and this is the only use.
3664 if (Value *Simplified = simplifyDemandedFPClassFnegFabs(
3665 Known, Src, DemandedMask: ThisDemandedMask, KnownSrc, /*NSZ=*/false))
3666 return Simplified;
3667 break;
3668 }
3669 case Instruction::Call: {
3670 const CallInst *CI = cast<CallInst>(Val: I);
3671 const Intrinsic::ID IID = CI->getIntrinsicID();
3672 switch (IID) {
3673 case Intrinsic::fabs: {
3674 Value *Src = CI->getArgOperand(i: 0);
3675 KnownFPClass KnownSrc =
3676 computeKnownFPClass(V: Src, InterestedClasses: fcAllFlags, SQ, Depth: Depth + 1);
3677
3678 // NSZ cannot be applied in multiple use case (maybe it could if all uses
3679 // were known nsz)
3680 if (Value *Simplified = simplifyDemandedFPClassFabs(
3681 Known, Src: CI->getArgOperand(i: 0), DemandedMask, KnownSrc,
3682 /*NSZ=*/false))
3683 return Simplified;
3684 break;
3685 }
3686 case Intrinsic::copysign: {
3687 Value *Mag = CI->getArgOperand(i: 0);
3688 Value *Sign = CI->getArgOperand(i: 1);
3689 KnownFPClass KnownMag =
3690 computeKnownFPClass(V: Mag, InterestedClasses: fcAllFlags, SQ, Depth: Depth + 1);
3691
3692 // Rule out some cases by magnitude, which may help prove the sign bit is
3693 // one direction or the other.
3694 KnownMag.knownNot(RuleOut: ~llvm::unknown_sign(Mask: DemandedMask));
3695
3696 // Cannot use nsz in the multiple use case.
3697 if (Value *Simplified = simplifyDemandedFPClassCopysignMag(
3698 MagSrc: Mag, DemandedMask, KnownSrc: KnownMag, /*NSZ=*/false))
3699 return Simplified;
3700
3701 KnownFPClass KnownSign =
3702 computeKnownFPClass(V: Sign, InterestedClasses: fcAllFlags, SQ, Depth: Depth + 1);
3703
3704 if (FMF.noInfs())
3705 KnownSign.knownNot(RuleOut: fcInf);
3706 if (FMF.noNaNs())
3707 KnownSign.knownNot(RuleOut: fcNan);
3708
3709 if (KnownSign.SignBit && KnownMag.SignBit &&
3710 *KnownSign.SignBit == *KnownMag.SignBit)
3711 return Mag;
3712
3713 Known = KnownFPClass::copysign(KnownMag, KnownSign);
3714 break;
3715 }
3716 case Intrinsic::maxnum:
3717 case Intrinsic::minnum:
3718 case Intrinsic::maximum:
3719 case Intrinsic::minimum:
3720 case Intrinsic::maximumnum:
3721 case Intrinsic::minimumnum: {
3722 KnownFPClass KnownRHS = computeKnownFPClass(V: CI->getArgOperand(i: 1),
3723 InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3724 if (KnownRHS.isUnknown())
3725 return nullptr;
3726
3727 KnownFPClass KnownLHS = computeKnownFPClass(V: CI->getArgOperand(i: 0),
3728 InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3729
3730 // Cannot use NSZ in the multiple use case.
3731 return simplifyDemandedFPClassMinMax(Known, IID, CI, DemandedMask,
3732 KnownLHS, KnownRHS, F,
3733 /*NSZ=*/false);
3734 }
3735 default:
3736 break;
3737 }
3738
3739 [[fallthrough]];
3740 }
3741 default:
3742 Known = computeKnownFPClass(V: I, InterestedClasses: DemandedMask, SQ, Depth: Depth + 1);
3743 Known.knownNot(RuleOut: ~DemandedMask);
3744 break;
3745 }
3746
3747 return getFPClassConstant(Ty: I->getType(), Mask: Known.KnownFPClasses);
3748}
3749
3750bool InstCombinerImpl::SimplifyDemandedFPClass(Instruction *I, unsigned OpNo,
3751 FPClassTest DemandedMask,
3752 KnownFPClass &Known,
3753 const SimplifyQuery &SQ,
3754 unsigned Depth) {
3755 Use &U = I->getOperandUse(i: OpNo);
3756 Value *V = U.get();
3757 Type *VTy = V->getType();
3758
3759 if (DemandedMask == fcNone) {
3760 if (isa<PoisonValue>(Val: V))
3761 return false;
3762 replaceUse(U, NewValue: PoisonValue::get(T: VTy));
3763 return true;
3764 }
3765
3766 // Handle constant
3767 Instruction *VInst = dyn_cast<Instruction>(Val: V);
3768 if (!VInst) {
3769 // Handle constants and arguments
3770 Known = computeKnownFPClass(V, InterestedClasses: fcAllFlags, SQ, Depth);
3771 Known.knownNot(RuleOut: ~DemandedMask);
3772
3773 if (Known.KnownFPClasses == fcNone) {
3774 if (isa<PoisonValue>(Val: V))
3775 return false;
3776 replaceUse(U, NewValue: PoisonValue::get(T: VTy));
3777 return true;
3778 }
3779
3780 // Do not try to replace values which are already constants (unless we are
3781 // folding to poison). Doing so could promote poison elements to non-poison
3782 // constants.
3783 if (isa<Constant>(Val: V))
3784 return false;
3785
3786 Value *FoldedToConst = getFPClassConstant(Ty: VTy, Mask: Known.KnownFPClasses);
3787 if (!FoldedToConst || FoldedToConst == V)
3788 return false;
3789
3790 replaceUse(U, NewValue: FoldedToConst);
3791 return true;
3792 }
3793
3794 if (Depth == MaxAnalysisRecursionDepth) {
3795 Known.knownNot(RuleOut: ~DemandedMask);
3796 return false;
3797 }
3798
3799 Value *NewVal;
3800
3801 if (VInst->hasOneUse()) {
3802 // If the instruction has one use, we can directly simplify it.
3803 NewVal = SimplifyDemandedUseFPClass(I: VInst, DemandedMask, Known, SQ, Depth);
3804 } else {
3805 // If there are multiple uses of this instruction, then we can simplify
3806 // VInst to some other value, but not modify the instruction.
3807 NewVal = SimplifyMultipleUseDemandedFPClass(I: VInst, DemandedMask, Known, SQ,
3808 Depth);
3809 }
3810
3811 if (!NewVal)
3812 return false;
3813 if (Instruction *OpInst = dyn_cast<Instruction>(Val&: U))
3814 salvageDebugInfo(I&: *OpInst);
3815
3816 replaceUse(U, NewValue: NewVal);
3817 return true;
3818}
3819