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SelectionDAG: slightly refactor DAGCombiner::visitSELECT_CC to avoid redudant checks...

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This doesn't really effect performance due to all the relevant calls being transparent but is clearer. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184027 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Stephen Lin 2013-06-15 04:03:33 +00:00
parent 702ff96ff3
commit 7e6d620336
1 changed files with 14 additions and 12 deletions
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26
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -4233,21 +4233,23 @@ SDValue DAGCombiner::visitSELECT_CC(SDNode *N) {
// Determine if the condition we're dealing with is constant
SDValue SCC = SimplifySetCC(getSetCCResultType(N0.getValueType()),
N0, N1, CC, SDLoc(N), false);
if (SCC.getNode()) AddToWorkList(SCC.getNode());
if (SCC.getNode()) {
AddToWorkList(SCC.getNode());
if (ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.getNode())) {
if (!SCCC->isNullValue())
return N2; // cond always true -> true val
else
return N3; // cond always false -> false val
if (ConstantSDNode *SCCC = dyn_cast<ConstantSDNode>(SCC.getNode())) {
if (!SCCC->isNullValue())
return N2; // cond always true -> true val
else
return N3; // cond always false -> false val
}
// Fold to a simpler select_cc
if (SCC.getOpcode() == ISD::SETCC)
return DAG.getNode(ISD::SELECT_CC, SDLoc(N), N2.getValueType(),
SCC.getOperand(0), SCC.getOperand(1), N2, N3,
SCC.getOperand(2));
}
// Fold to a simpler select_cc
if (SCC.getNode() && SCC.getOpcode() == ISD::SETCC)
return DAG.getNode(ISD::SELECT_CC, SDLoc(N), N2.getValueType(),
SCC.getOperand(0), SCC.getOperand(1), N2, N3,
SCC.getOperand(2));
// If we can fold this based on the true/false value, do so.
if (SimplifySelectOps(N, N2, N3))
return SDValue(N, 0); // Don't revisit N.