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[InstCombine] fold (a == 1 && b != 0) || (a != 0 && b == 0)) to `(a ==
0) != (b == 0)`
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‎llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3421,6 +3421,29 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
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return foldAndOrOfICmpsUsingRanges(LHS, RHS, IsAnd);
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}
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Value *foldAorBZero(BinaryOperator &I, InstCombiner::BuilderTy &Builder) {
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Value *Op0 = I.getOperand(0);
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Value *Op1 = I.getOperand(1);
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if (!Op0->hasOneUse() || !Op1->hasOneUse())
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return nullptr;
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// match each operand of I with and
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Value *A, *B;
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CmpInst::Predicate Pred = CmpInst::ICMP_EQ;
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CmpInst::Predicate InPred = CmpInst::ICMP_EQ;
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bool IsOp0 = match(Op0, m_c_And(m_Cmp(Pred, m_Value(A), m_ZeroInt()),
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m_Cmp(InPred, m_Value(B), m_ZeroInt())));
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bool IsOp1 = match(Op1, m_c_And(m_Cmp(InPred, m_Specific(A), m_ZeroInt()),
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m_Cmp(Pred, m_Specific(B), m_ZeroInt())));
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if (!IsOp0 || !IsOp1)
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return nullptr;
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Constant *Zero = ConstantInt::getNullValue(A->getType());
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auto *LHS = Builder.CreateICmpEQ(A, Zero);
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auto *RHS = Builder.CreateICmpEQ(B, Zero);
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return Builder.CreateICmpNE(LHS, RHS);
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}
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// FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
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// here. We should standardize that construct where it is needed or choose some
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// other way to ensure that commutated variants of patterns are not missed.
@@ -3450,6 +3473,10 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
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if (Instruction *X = foldComplexAndOrPatterns(I, Builder))
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return X;
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// (A == 0 & B != 0) | (A != 0 & B == 0)) -> (A == 0) != (B == 0)
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if (Value *V = foldAorBZero(I, Builder))
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return replaceInstUsesWith(I, V);
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// (A&B)|(A&C) -> A&(B|C) etc
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if (Value *V = foldUsingDistributiveLaws(I))
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return replaceInstUsesWith(I, V);

‎llvm/test/Transforms/InstCombine/fold-a-or-b-zero.ll

Lines changed: 104 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,104 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt < %s -S -passes=instcombine | FileCheck %s
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declare void @use(i1)
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define void @a_or_b(i32 %a, i32 %b) {
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; CHECK-LABEL: define void @src(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_EQ_ZERO:%.*]] = icmp eq i32 [[A]], 0
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; CHECK-NEXT: [[B_NE_ZERO:%.*]] = icmp ne i32 [[B]], 0
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; CHECK-NEXT: [[AND_1:%.*]] = and i1 [[A_EQ_ZERO]], [[B_NE_ZERO]]
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; CHECK-NEXT: [[A_NE_ZERO:%.*]] = icmp ne i32 [[A]], 0
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; CHECK-NEXT: [[B_EQ_ZERO:%.*]] = icmp eq i32 [[B]], 0
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; CHECK-NEXT: [[AND_2:%.*]] = and i1 [[A_NE_ZERO]], [[B_EQ_ZERO]]
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; CHECK-NEXT: [[OR:%.*]] = or i1 [[AND_1]], [[AND_2]]
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; CHECK-NEXT: call void @use(i1 [[OR]])
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; CHECK-NEXT: ret void
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;
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%a_eq_zero = icmp eq i32 %a, 0
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%b_ne_zero = icmp ne i32 %b, 0
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%and.1 = and i1 %a_eq_zero, %b_ne_zero
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%a_ne_zero = icmp ne i32 %a, 0
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%b_eq_zero = icmp eq i32 %b, 0
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%and.2 = and i1 %a_ne_zero, %b_eq_zero
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%or = or i1 %and.1, %and.2
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call void @use(i1 %or)
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ret void
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}
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define void @a_or_b_zero(i32 %a, i32 %b) {
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; CHECK-LABEL: define void @src(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_EQ_ZERO:%.*]] = icmp eq i32 [[A]], 0
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; CHECK-NEXT: [[B_NE_ZERO:%.*]] = icmp ne i32 [[B]], 0
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; CHECK-NEXT: [[AND_1:%.*]] = and i1 [[A_EQ_ZERO]], [[B_NE_ZERO]]
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; CHECK-NEXT: [[A_NE_ZERO:%.*]] = icmp ne i32 [[A]], 0
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; CHECK-NEXT: [[B_EQ_ZERO:%.*]] = icmp eq i32 [[B]], 0
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; CHECK-NEXT: [[AND_2:%.*]] = and i1 [[A_NE_ZERO]], [[B_EQ_ZERO]]
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; CHECK-NEXT: [[OR:%.*]] = or i1 [[AND_1]], [[AND_2]]
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; CHECK-NEXT: call void @use(i1 [[OR]])
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; CHECK-NEXT: ret void
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;
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%a_eq_zero = icmp eq i32 %a, 0
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%b_ne_zero = icmp ne i32 %b, 0
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%and.1 = and i1 %a_eq_zero, %b_ne_zero
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%a_ne_zero = icmp ne i32 %a, 0
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%b_eq_zero = icmp eq i32 %b, 0
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%and.2 = and i1 %a_ne_zero, %b_eq_zero
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%or = or i1 %and.1, %and.2
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call void @use(i1 %or)
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ret void
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}
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define void @a_or_b_multiple_uses(i32 %a, i32 %b) {
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; CHECK-LABEL: define void @src(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_EQ_ZERO:%.*]] = icmp eq i32 [[A]], 0
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; CHECK-NEXT: [[B_NE_ZERO:%.*]] = icmp ne i32 [[B]], 0
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; CHECK-NEXT: [[AND_1:%.*]] = and i1 [[A_EQ_ZERO]], [[B_NE_ZERO]]
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; CHECK-NEXT: [[A_NE_ZERO:%.*]] = icmp ne i32 [[A]], 0
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; CHECK-NEXT: [[B_EQ_ZERO:%.*]] = icmp eq i32 [[B]], 0
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; CHECK-NEXT: [[AND_2:%.*]] = and i1 [[A_NE_ZERO]], [[B_EQ_ZERO]]
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; CHECK-NEXT: [[OR:%.*]] = or i1 [[AND_1]], [[AND_2]]
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; CHECK-NEXT: call void @use(i1 [[OR]])
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; CHECK-NEXT: ret void
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;
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%a_eq_zero = icmp eq i32 %a, 0
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%b_ne_zero = icmp ne i32 %b, 0
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%and.1 = and i1 %a_eq_zero, %b_ne_zero
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%a_ne_zero = icmp ne i32 %a, 0
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%b_eq_zero = icmp eq i32 %b, 0
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%and.2 = and i1 %a_ne_zero, %b_eq_zero
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call void @use(i1 %and.2)
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%or = or i1 %and.1, %and.2
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ret void
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}
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define void @a_or_b_multiple_uses_2(i32 %a, i32 %b) {
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; CHECK-LABEL: define void @src(
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; CHECK-SAME: i32 [[A:%.*]], i32 [[B:%.*]]) {
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; CHECK-NEXT: [[A_EQ_ZERO:%.*]] = icmp eq i32 [[A]], 0
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; CHECK-NEXT: [[B_NE_ZERO:%.*]] = icmp ne i32 [[B]], 0
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; CHECK-NEXT: [[AND_1:%.*]] = and i1 [[A_EQ_ZERO]], [[B_NE_ZERO]]
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; CHECK-NEXT: [[A_NE_ZERO:%.*]] = icmp ne i32 [[A]], 0
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; CHECK-NEXT: [[B_EQ_ZERO:%.*]] = icmp eq i32 [[B]], 0
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; CHECK-NEXT: [[AND_2:%.*]] = and i1 [[A_NE_ZERO]], [[B_EQ_ZERO]]
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; CHECK-NEXT: [[OR:%.*]] = or i1 [[AND_1]], [[AND_2]]
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; CHECK-NEXT: call void @use(i1 [[OR]])
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; CHECK-NEXT: ret void
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;
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%a_eq_zero = icmp eq i32 %a, 0
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%b_ne_zero = icmp ne i32 %b, 0
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call void @use(i1 %b_ne_zero)
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%and.1 = and i1 %a_eq_zero, %b_ne_zero
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%a_ne_zero = icmp ne i32 %a, 0
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%b_eq_zero = icmp eq i32 %b, 0
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%and.2 = and i1 %a_ne_zero, %b_eq_zero
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call void @use(i1 %and.1)
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%or = or i1 %and.1, %and.2
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ret void
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}
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