[llvm] [InstCombine] move foldAndOrOfICmpsOfAndWithPow2 into foldLogOpOfMaskedICmps (PR #121970)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 8 02:13:06 PST 2025
================
@@ -587,93 +588,111 @@ static Value *foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
return Builder.CreateICmp(NewCC, NewAnd2, A);
}
- // Remaining cases assume at least that B and D are constant, and depend on
- // their actual values. This isn't strictly necessary, just a "handle the
- // easy cases for now" decision.
const APInt *ConstB, *ConstD;
- if (!match(B, m_APInt(ConstB)) || !match(D, m_APInt(ConstD)))
- return nullptr;
-
- if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) {
- // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
- // (icmp ne (A & B), B) & (icmp ne (A & D), D)
- // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
- // Only valid if one of the masks is a superset of the other (check "B&D" is
- // the same as either B or D).
- APInt NewMask = *ConstB & *ConstD;
- if (NewMask == *ConstB)
- return LHS;
- else if (NewMask == *ConstD)
- return RHS;
- }
-
- if (Mask & AMask_NotAllOnes) {
- // (icmp ne (A & B), B) & (icmp ne (A & D), D)
- // -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
- // Only valid if one of the masks is a superset of the other (check "B|D" is
- // the same as either B or D).
- APInt NewMask = *ConstB | *ConstD;
- if (NewMask == *ConstB)
- return LHS;
- else if (NewMask == *ConstD)
- return RHS;
- }
-
- if (Mask & (BMask_Mixed | BMask_NotMixed)) {
- // Mixed:
- // (icmp eq (A & B), C) & (icmp eq (A & D), E)
- // We already know that B & C == C && D & E == E.
- // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
- // C and E, which are shared by both the mask B and the mask D, don't
- // contradict, then we can transform to
- // -> (icmp eq (A & (B|D)), (C|E))
- // Currently, we only handle the case of B, C, D, and E being constant.
- // We can't simply use C and E because we might actually handle
- // (icmp ne (A & B), B) & (icmp eq (A & D), D)
- // with B and D, having a single bit set.
-
- // NotMixed:
- // (icmp ne (A & B), C) & (icmp ne (A & D), E)
- // -> (icmp ne (A & (B & D)), (C & E))
- // Check the intersection (B & D) for inequality.
- // Assume that (B & D) == B || (B & D) == D, i.e B/D is a subset of D/B
- // and (B & D) & (C ^ E) == 0, bits of C and E, which are shared by both the
- // B and the D, don't contradict.
- // Note that we can assume (~B & C) == 0 && (~D & E) == 0, previous
- // operation should delete these icmps if it hadn't been met.
-
- const APInt *OldConstC, *OldConstE;
- if (!match(C, m_APInt(OldConstC)) || !match(E, m_APInt(OldConstE)))
- return nullptr;
-
- auto FoldBMixed = [&](ICmpInst::Predicate CC, bool IsNot) -> Value * {
- CC = IsNot ? CmpInst::getInversePredicate(CC) : CC;
- const APInt ConstC = PredL != CC ? *ConstB ^ *OldConstC : *OldConstC;
- const APInt ConstE = PredR != CC ? *ConstD ^ *OldConstE : *OldConstE;
+ if (match(B, m_APInt(ConstB)) && match(D, m_APInt(ConstD))) {
+
+ if (Mask & (Mask_NotAllZeros | BMask_NotAllOnes)) {
+ // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
+ // (icmp ne (A & B), B) & (icmp ne (A & D), D)
+ // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
+ // Only valid if one of the masks is a superset of the other (check "B&D"
+ // is the same as either B or D).
+ APInt NewMask = *ConstB & *ConstD;
+ if (NewMask == *ConstB)
+ return LHS;
+ if (NewMask == *ConstD)
+ return RHS;
+ }
- if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue())
- return IsNot ? nullptr : ConstantInt::get(LHS->getType(), !IsAnd);
+ if (Mask & AMask_NotAllOnes) {
+ // (icmp ne (A & B), B) & (icmp ne (A & D), D)
+ // -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
+ // Only valid if one of the masks is a superset of the other (check "B|D"
+ // is the same as either B or D).
+ APInt NewMask = *ConstB | *ConstD;
+ if (NewMask == *ConstB)
+ return LHS;
+ if (NewMask == *ConstD)
+ return RHS;
+ }
- if (IsNot && !ConstB->isSubsetOf(*ConstD) && !ConstD->isSubsetOf(*ConstB))
+ if (Mask & (BMask_Mixed | BMask_NotMixed)) {
+ // Mixed:
+ // (icmp eq (A & B), C) & (icmp eq (A & D), E)
+ // We already know that B & C == C && D & E == E.
+ // If we can prove that (B & D) & (C ^ E) == 0, that is, the bits of
+ // C and E, which are shared by both the mask B and the mask D, don't
+ // contradict, then we can transform to
+ // -> (icmp eq (A & (B|D)), (C|E))
+ // Currently, we only handle the case of B, C, D, and E being constant.
+ // We can't simply use C and E because we might actually handle
+ // (icmp ne (A & B), B) & (icmp eq (A & D), D)
+ // with B and D, having a single bit set.
+
+ // NotMixed:
+ // (icmp ne (A & B), C) & (icmp ne (A & D), E)
+ // -> (icmp ne (A & (B & D)), (C & E))
+ // Check the intersection (B & D) for inequality.
+ // Assume that (B & D) == B || (B & D) == D, i.e B/D is a subset of D/B
+ // and (B & D) & (C ^ E) == 0, bits of C and E, which are shared by both
+ // the B and the D, don't contradict. Note that we can assume (~B & C) ==
+ // 0 && (~D & E) == 0, previous operation should delete these icmps if it
+ // hadn't been met.
+
+ const APInt *OldConstC, *OldConstE;
+ if (!match(C, m_APInt(OldConstC)) || !match(E, m_APInt(OldConstE)))
return nullptr;
- APInt BD, CE;
- if (IsNot) {
- BD = *ConstB & *ConstD;
- CE = ConstC & ConstE;
- } else {
- BD = *ConstB | *ConstD;
- CE = ConstC | ConstE;
- }
- Value *NewAnd = Builder.CreateAnd(A, BD);
- Value *CEVal = ConstantInt::get(A->getType(), CE);
- return Builder.CreateICmp(CC, CEVal, NewAnd);
- };
+ auto FoldBMixed = [&](ICmpInst::Predicate CC, bool IsNot) -> Value * {
+ CC = IsNot ? CmpInst::getInversePredicate(CC) : CC;
+ const APInt ConstC = PredL != CC ? *ConstB ^ *OldConstC : *OldConstC;
+ const APInt ConstE = PredR != CC ? *ConstD ^ *OldConstE : *OldConstE;
+
+ if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue())
+ return IsNot ? nullptr : ConstantInt::get(LHS->getType(), !IsAnd);
+
+ if (IsNot && !ConstB->isSubsetOf(*ConstD) &&
+ !ConstD->isSubsetOf(*ConstB))
+ return nullptr;
+
+ APInt BD, CE;
+ if (IsNot) {
+ BD = *ConstB & *ConstD;
+ CE = ConstC & ConstE;
+ } else {
+ BD = *ConstB | *ConstD;
+ CE = ConstC | ConstE;
+ }
+ Value *NewAnd = Builder.CreateAnd(A, BD);
+ Value *CEVal = ConstantInt::get(A->getType(), CE);
+ return Builder.CreateICmp(CC, CEVal, NewAnd);
+ };
+
+ if (Mask & BMask_Mixed)
+ return FoldBMixed(NewCC, false);
+ if (Mask & BMask_NotMixed) // can be else also
+ return FoldBMixed(NewCC, true);
+ }
+ }
- if (Mask & BMask_Mixed)
- return FoldBMixed(NewCC, false);
- if (Mask & BMask_NotMixed) // can be else also
- return FoldBMixed(NewCC, true);
+ // (icmp eq (A & B), 0) | (icmp eq (A & D), 0)
+ // -> (icmp ne (A & (B|D)), (B|D))
+ // (icmp ne (A & B), 0) & (icmp ne (A & D), 0)
+ // -> (icmp eq (A & (B|D)), (B|D))
+ // iff B and D is known to be a power of two
+ if (Mask & Mask_NotAllZeros &&
+ isKnownToBeAPowerOfTwo(B, Q.DL, /*OrZero=*/false, /*Depth=*/0, Q.AC,
+ Q.CxtI, Q.DT) &&
----------------
nikic wrote:
```suggestion
isKnownToBeAPowerOfTwo(B, /*OrZero=*/false, /*Depth=*/0, Q) &&
```
https://github.com/llvm/llvm-project/pull/121970
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