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[InstCombine] Pass disjoint in or combine #138800

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Merged
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May 8, 2025
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[InstCombine] Pass disjoint in or combine #138800

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638421c
[NFC] precommit test case.
fengfeng09 May 7, 2025
a6b000f
[InstCombine] Keep the disjoint flag when combining two ORs if possible.
fengfeng09 May 7, 2025
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13 changes: 12 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3894,12 +3894,23 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
// be simplified by a later pass either, so we try swapping the inner/outer
// ORs in the hopes that we'll be able to simplify it this way.
// (X|C) | V --> (X|V) | C
// Pass the disjoint flag in the following two patterns:
// 1. or-disjoint (or-disjoint X, C), V -->
// or-disjoint (or-disjoint X, V), C
//
// 2. or-disjoint (or X, C), V -->
// or (or-disjoint X, V), C
ConstantInt *CI;
if (Op0->hasOneUse() && !match(Op1, m_ConstantInt()) &&
match(Op0, m_Or(m_Value(A), m_ConstantInt(CI)))) {
bool IsDisjointOuter = cast<PossiblyDisjointInst>(I).isDisjoint();
bool IsDisjointInner = cast<PossiblyDisjointInst>(Op0)->isDisjoint();
Value *Inner = Builder.CreateOr(A, Op1);
cast<PossiblyDisjointInst>(Inner)->setIsDisjoint(IsDisjointOuter);
Inner->takeName(Op0);
return BinaryOperator::CreateOr(Inner, CI);
return IsDisjointOuter && IsDisjointInner
? BinaryOperator::CreateDisjointOr(Inner, CI)
: BinaryOperator::CreateOr(Inner, CI);
}

// Change (or (bool?A:B),(bool?C:D)) --> (bool?(or A,C):(or B,D))
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48 changes: 48 additions & 0 deletions llvm/test/Transforms/InstCombine/or-or-combine.ll
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@@ -0,0 +1,48 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -passes=instcombine < %s | FileCheck %s

; (X | C) | Y --> (X | Y) | C

define i32 @test1(i32 %x, i32 %y) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: [[INNER:%.*]] = or disjoint i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[OUTER:%.*]] = or disjoint i32 [[INNER]], 5
; CHECK-NEXT: ret i32 [[OUTER]]
;
%inner = or disjoint i32 %x, 5
%outer = or disjoint i32 %inner, %y
ret i32 %outer
}

define i32 @test2(i32 %x, i32 %y) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[INNER:%.*]] = or disjoint i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[OUTER:%.*]] = or i32 [[INNER]], 5
; CHECK-NEXT: ret i32 [[OUTER]]
;
%inner = or i32 %x, 5
%outer = or disjoint i32 %inner, %y
ret i32 %outer
}

define i32 @test3(i32 %x, i32 %y) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: [[INNER:%.*]] = or i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[OUTER:%.*]] = or i32 [[INNER]], 5
; CHECK-NEXT: ret i32 [[OUTER]]
;
%inner = or disjoint i32 %x, 5
%outer = or i32 %inner, %y
ret i32 %outer
}

define i32 @test4(i32 %x, i32 %y) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: [[INNER:%.*]] = or i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[OUTER:%.*]] = or i32 [[INNER]], 5
; CHECK-NEXT: ret i32 [[OUTER]]
;
%inner = or i32 %x, 5
%outer = or i32 %inner, %y
ret i32 %outer
}
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