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completely remove a transformation that is unsafe in the face of 

undefs.

llvm-svn: 40439
This commit is contained in:
Chris Lattner 2007-07-23 17:10:17 +00:00
parent 54f4d2bd57
commit 4512cd2cab
1 changed files with 0 additions and 36 deletions
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36
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3870,42 +3870,6 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
InsertNewInstBefore(BinaryOperator::createOr(V2, V3, "tmp"), I);
return BinaryOperator::createAnd(V1, Or);
}
// (V1 & V3)|(V2 & ~V3) -> ((V1 ^ V2) & V3) ^ V2
// Disable this transformations temporarily. This causes
// mis-compilation when V2 is undefined.
if (0 && isOnlyUse(Op0) && isOnlyUse(Op1)) {
// Try all combination of terms to find V3 and ~V3.
if (A->hasOneUse() && match(A, m_Not(m_Value(V3)))) {
if (V3 == B)
V1 = D, V2 = C;
else if (V3 == D)
V1 = B, V2 = C;
}
if (B->hasOneUse() && match(B, m_Not(m_Value(V3)))) {
if (V3 == A)
V1 = C, V2 = D;
else if (V3 == C)
V1 = A, V2 = D;
}
if (C->hasOneUse() && match(C, m_Not(m_Value(V3)))) {
if (V3 == B)
V1 = D, V2 = A;
else if (V3 == D)
V1 = B, V2 = A;
}
if (D->hasOneUse() && match(D, m_Not(m_Value(V3)))) {
if (V3 == A)
V1 = C, V2 = B;
else if (V3 == C)
V1 = A, V2 = B;
}
if (V1) {
A = InsertNewInstBefore(BinaryOperator::createXor(V1, V2, "tmp"), I);
A = InsertNewInstBefore(BinaryOperator::createAnd(A, V3, "tmp"), I);
return BinaryOperator::createXor(A, V2);
}
}
}
}