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Emit:

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cmpl    %eax, %ecx
        setae   %al
        movzbl  %al, %eax

instead of:

        cmpl    %eax, %ecx
        setb    %al
        xorb    $1, %al
        movzbl  %al, %eax

when using logical not of a C comparison.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41807 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-09-10 21:39:07 +00:00
parent 8de5f1cc7b
commit 61c5ff460b
1 changed files with 10 additions and 0 deletions
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10
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -1941,6 +1941,16 @@ SDOperand DAGCombiner::visitXOR(SDNode *N) {
assert(0 && "Unhandled SetCC Equivalent!");
abort();
}
// fold (not (zext (setcc x, y))) -> (zext (not (setcc x, y)))
if (N1C && N1C->getValue() == 1 && N0.getOpcode() == ISD::ZERO_EXTEND &&
N0.Val->hasOneUse() && isSetCCEquivalent(N0.getOperand(0), LHS, RHS, CC)){
SDOperand V = N0.getOperand(0);
V = DAG.getNode(ISD::XOR, V.getValueType(), V,
DAG.getConstant(V.getValueType(), 1));
AddToWorkList(V.Val);
return DAG.getNode(ISD::ZERO_EXTEND, VT, V);
}
// fold !(x or y) -> (!x and !y) iff x or y are setcc
if (N1C && N1C->getValue() == 1 && VT == MVT::i1 &&
(N0.getOpcode() == ISD::OR || N0.getOpcode() == ISD::AND)) {