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DAGCombiner: Continue combining if FoldConstantArithmetic() fails.

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DAG.FoldConstantArithmetic() can fail even though both operands are
Constants if OpaqueConstants are involved. Continue trying other combine
possibilities in tis case.

Differential Revision: http://reviews.llvm.org/D6946

Somewhat related to PR21801 / rdar://19211454

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237822 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matthias Braun
2015-05-20 18:54:02 +00:00
parent d594ba0815
commit fa3d0dc026
2 changed files with 105 additions and 73 deletions
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12
lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -1086,9 +1086,19 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
// If we know the value of all of the demanded bits, return this as a
// constant.
if ((NewMask & (KnownZero|KnownOne)) == NewMask)
if ((NewMask & (KnownZero|KnownOne)) == NewMask) {
// Avoid folding to a constant if any OpaqueConstant is involved.
const SDNode *N = Op.getNode();
for (SDNodeIterator I = SDNodeIterator::begin(N),
E = SDNodeIterator::end(N); I != E; ++I) {
SDNode *Op = *I;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op))
if (C->isOpaque())
return false;
}
return TLO.CombineTo(Op,
TLO.DAG.getConstant(KnownOne, dl, Op.getValueType()));
}
return false;
}