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DAG Combiner: Fold SelectCC When Cond is UNDEF

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In case folding a node end up with a NaN as operand for the select, 
the folding of the condition of the selectcc node returns "UNDEF".

Differential Revision: http://reviews.llvm.org/D6889



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225952 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mehdi Amini 2015-01-14 05:45:24 +00:00
parent 125de50e12
commit cfe92407cd
1 changed files with 7 additions and 4 deletions
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11
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -5100,13 +5100,16 @@ SDValue DAGCombiner::visitSELECT_CC(SDNode *N) {
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)
} else if (SCC->getOpcode() == ISD::UNDEF) {
// When the condition is UNDEF, just return the first operand. This is
// coherent the DAG creation, no setcc node is created in this case
return N2;
} else if (SCC.getOpcode() == ISD::SETCC) {
// Fold to a simpler select_cc
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.