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Implement PR2298. This transforms: 

~x < ~y --> y < x
   -x == -y --> x == y

llvm-svn: 50882
This commit is contained in:
Chris Lattner 2008-05-09 05:19:28 +00:00
parent e7f0afe168
commit aaba10e843
3 changed files with 33 additions and 0 deletions
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13
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -5658,8 +5658,21 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
return R;
}
// ~x < ~y --> y < x
{ Value *A, *B;
if (match(Op0, m_Not(m_Value(A))) &&
match(Op1, m_Not(m_Value(B))))
return new ICmpInst(I.getPredicate(), B, A);
}
if (I.isEquality()) {
Value *A, *B, *C, *D;
// -x == -y --> x == y
if (match(Op0, m_Neg(m_Value(A))) &&
match(Op1, m_Neg(m_Value(B))))
return new ICmpInst(I.getPredicate(), A, B);
if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
Value *OtherVal = A == Op1 ? B : A;

10
llvm/test/Transforms/InstCombine/not.ll
View File

@ -42,3 +42,13 @@ define i32 @test5(i32 %A, i32 %B) {
ret i32 %d
}
; PR2298
define i8 @test6(i32 %a, i32 %b) zeroext nounwind {
entry:
%tmp1not = xor i32 %a, -1 ; <i32> [#uses=1]
%tmp2not = xor i32 %b, -1 ; <i32> [#uses=1]
%tmp3 = icmp slt i32 %tmp1not, %tmp2not ; <i1> [#uses=1]
%retval67 = zext i1 %tmp3 to i8 ; <i8> [#uses=1]
ret i8 %retval67
}

10
llvm/test/Transforms/InstCombine/sub.ll
View File

@ -134,3 +134,13 @@ define i1 @test21(i32 %g, i32 %h) {
%tmp.4 = icmp ne i32 %tmp.2, %g ; <i1> [#uses=1]
ret i1 %tmp.4
}
; PR2298
define i8 @test22(i32 %a, i32 %b) zeroext nounwind {
%tmp2 = sub i32 0, %a ; <i32> [#uses=1]
%tmp4 = sub i32 0, %b ; <i32> [#uses=1]
%tmp5 = icmp eq i32 %tmp2, %tmp4 ; <i1> [#uses=1]
%retval89 = zext i1 %tmp5 to i8 ; <i8> [#uses=1]
ret i8 %retval89
}