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[InstCombine] Fold (A | B) ^ (A & C) --> A ? ~C : B #121906

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Merged
merged 2 commits into from
Jan 7, 2025
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[InstCombine] Fold (A | B) ^ (A & C) --> A ? ~C : B #121906

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d0680ff
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Jan 7, 2025
83c68c8
[InstCombine] Fold `(A | B) ^ (A & C) --> A ? ~C : B`
dtcxzyw Jan 7, 2025
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4 changes: 2 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Expand Up @@ -4972,8 +4972,8 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {

// (A & B) ^ (A | C) --> A ? ~B : C -- There are 4 commuted variants.
if (I.getType()->isIntOrIntVectorTy(1) &&
match(Op0, m_OneUse(m_LogicalAnd(m_Value(A), m_Value(B)))) &&
match(Op1, m_OneUse(m_LogicalOr(m_Value(C), m_Value(D))))) {
match(&I, m_c_Xor(m_OneUse(m_LogicalAnd(m_Value(A), m_Value(B))),
m_OneUse(m_LogicalOr(m_Value(C), m_Value(D)))))) {
bool NeedFreeze = isa<SelectInst>(Op0) && isa<SelectInst>(Op1) && B == D;
if (B == C || B == D)
std::swap(A, B);
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12 changes: 12 additions & 0 deletions llvm/test/Transforms/InstCombine/xor-and-or.ll
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Expand Up @@ -25,6 +25,18 @@ define i1 @xor_logic_and_logic_or2(i1 %c, i1 %x, i1 %y) {
ret i1 %r
}

define i1 @xor_logic_and_logic_or2_commuted(i1 %c, i1 %x, i1 %y) {
; CHECK-LABEL: @xor_logic_and_logic_or2_commuted(
; CHECK-NEXT: [[TMP1:%.*]] = xor i1 [[X:%.*]], true
; CHECK-NEXT: [[R:%.*]] = select i1 [[C:%.*]], i1 [[TMP1]], i1 [[Y:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%o = select i1 %y, i1 true, i1 %c
%a = select i1 %c, i1 %x, i1 false
%r = xor i1 %o, %a
ret i1 %r
}

define i1 @xor_logic_and_logic_or3(i1 %c, i1 %x, i1 %y) {
; CHECK-LABEL: @xor_logic_and_logic_or3(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[C:%.*]]
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