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InstCombine: Remove a special case pattern 

The special case did not work when run under -reassociate and can easily
be expressed by a further generalization of an existing pattern.

llvm-svn: 217227
This commit is contained in:
David Majnemer 2014-09-05 06:09:24 +00:00
parent c0f7933512
commit 6fe6ea740c
2 changed files with 38 additions and 20 deletions
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31
llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
View File

@ -2614,17 +2614,25 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B))))) {
return BinaryOperator::CreateXor(A, B);
}
// (A ^ B)^(A | B) -> A & B
if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) &&
match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
if ((A == C && B == D) || (A == D && B == C))
return BinaryOperator::CreateAnd(A, B);
// (A ^ C)^(A | B) -> ((~A) & B) ^ C
if (match(Op0I, m_Xor(m_Value(D), m_Value(C))) &&
match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
if (D == A)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(A), B), C);
if (D == B)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(B), A), C);
}
// (A | B)^(A ^ B) -> A & B
// (A | B)^(A ^ C) -> ((~A) & B) ^ C
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
match(Op1I, m_Xor(m_Value(C), m_Value(D)))) {
if ((A == C && B == D) || (A == D && B == C))
return BinaryOperator::CreateAnd(A, B);
match(Op1I, m_Xor(m_Value(D), m_Value(C)))) {
if (D == A)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(A), B), C);
if (D == B)
return BinaryOperator::CreateXor(
Builder->CreateAnd(Builder->CreateNot(B), A), C);
}
// (A & B) ^ (A ^ B) -> (A | B)
if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
@ -2636,12 +2644,7 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
return BinaryOperator::CreateOr(A, B);
}
// (A | B)^(~A) -> (A | ~B)
Value *A = nullptr, *B = nullptr;
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
match(Op1, m_Not(m_Specific(A))))
return BinaryOperator::CreateOr(A, Builder->CreateNot(B));
// (A & ~B) ^ (~A) -> ~(A & B)
if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
match(Op1, m_Not(m_Specific(A))))

27
llvm/test/Transforms/InstCombine/xor2.ll
View File

@ -85,25 +85,27 @@ define i32 @test6(i32 %x) {
; (A | B) ^ (~A) -> (A | ~B)
define i32 @test7(i32 %a, i32 %b) #0 {
define i32 @test7(i32 %a, i32 %b) {
%or = or i32 %a, %b
%neg = xor i32 %a, -1
%xor = xor i32 %or, %neg
ret i32 %xor
; CHECK-LABEL: @test7(
; CHECK-NEXT: %1 = xor i32 %b, -1
; CHECK-NEXT: %xor = or i32 %a, %1
; CHECK-NEXT: %[[b_not:.*]] = xor i32 %b, -1
; CHECK-NEXT: %[[or:.*]] = or i32 %a, %[[b_not]]
; CHECK-NEXT: ret i32 %[[or]]
}
; (~A) ^ (A | B) -> (A | ~B)
define i32 @test8(i32 %a, i32 %b) #0 {
define i32 @test8(i32 %a, i32 %b) {
%neg = xor i32 %a, -1
%or = or i32 %a, %b
%xor = xor i32 %neg, %or
ret i32 %xor
; CHECK-LABEL: @test8(
; CHECK-NEXT: %1 = xor i32 %b, -1
; CHECK-NEXT: %xor = or i32 %a, %1
; CHECK-NEXT: %[[b_not:.*]] = xor i32 %b, -1
; CHECK-NEXT: %[[or:.*]] = or i32 %a, %[[b_not]]
; CHECK-NEXT: ret i32 %[[or]]
}
; (A & B) ^ (A ^ B) -> (A | B)
@ -167,3 +169,16 @@ define i32 @test14(i32 %a, i32 %b) {
; CHECK-NEXT: %1 = and i32 %a, %b
; CHECK-NEXT: %xor = xor i32 %1, -1
}
; (A ^ C) ^ (A | B) -> ((~A) & B) ^ C
define i32 @test15(i32 %a, i32 %b, i32 %c) {
%neg = xor i32 %a, %c
%or = or i32 %a, %b
%xor = xor i32 %neg, %or
ret i32 %xor
; CHECK-LABEL: @test15(
; CHECK-NEXT: %[[not:.*]] = xor i32 %a, -1
; CHECK-NEXT: %[[and:.*]] = and i32 %[[not]], %b
; CHECK-NEXT: %[[xor:.*]] = xor i32 %[[and]], %c
; CHECK-NEXT: ret i32 %[[xor]]
}