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Added InstCombine transform for pattern "(A & B) ^ (A ^ B) -> (A | B)"

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Patch idea by Ankit Jain !

Differential Revision: http://reviews.llvm.org/D4618



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213677 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Suyog Sarda 2014-07-22 18:30:54 +00:00
parent 1a1b1f708d
commit 3326ee444a
2 changed files with 28 additions and 0 deletions
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8
lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
View File

@ -2454,6 +2454,14 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if ((A == C && B == D) || (A == D && B == C))
return BinaryOperator::CreateXor(A, B);
}
// (A & B) ^ (A ^ B) -> (A | B)
if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
match(Op1I, m_Xor(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
// (A ^ B) ^ (A & B) -> (A | B)
if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1I, m_And(m_Specific(A), m_Specific(B))))
return BinaryOperator::CreateOr(A, B);
}
// (A | B)^(~A) -> (A | ~B)

20
test/Transforms/InstCombine/xor2.ll
View File

@ -105,3 +105,23 @@ define i32 @test8(i32 %a, i32 %b) #0 {
; CHECK-NEXT: %1 = xor i32 %b, -1
; CHECK-NEXT: %xor = or i32 %a, %1
}
; (A & B) ^ (A ^ B) -> (A | B)
define i32 @test9(i32 %b, i32 %c) {
%and = and i32 %b, %c
%xor = xor i32 %b, %c
%xor2 = xor i32 %and, %xor
ret i32 %xor2
; CHECK-LABEL: @test9(
; CHECK-NEXT: %xor2 = or i32 %b, %c
}
; (A ^ B) ^ (A & B) -> (A | B)
define i32 @test10(i32 %b, i32 %c) {
%xor = xor i32 %b, %c
%and = and i32 %b, %c
%xor2 = xor i32 %xor, %and
ret i32 %xor2
; CHECK-LABEL: @test10(
; CHECK-NEXT: %xor2 = or i32 %b, %c
}