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fold fp_round(fp_round(x)) -> fp_round(x).

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46304 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-01-24 06:45:35 +00:00
parent 7323999b31
commit 0aa5e6f3fb
1 changed files with 9 additions and 0 deletions
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9
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -3648,6 +3648,15 @@ SDOperand DAGCombiner::visitFP_ROUND(SDNode *N) {
if (N0.getOpcode() == ISD::FP_EXTEND && VT == N0.getOperand(0).getValueType())
return N0.getOperand(0);
// fold (fp_round (fp_round x)) -> (fp_round x)
if (N0.getOpcode() == ISD::FP_ROUND) {
// This is a value preserving truncation if both round's are.
bool IsTrunc = N->getConstantOperandVal(1) == 1 &&
N0.Val->getConstantOperandVal(1) == 1;
return DAG.getNode(ISD::FP_ROUND, VT, N0.getOperand(0),
DAG.getIntPtrConstant(IsTrunc));
}
// fold (fp_round (copysign X, Y)) -> (copysign (fp_round X), Y)
if (N0.getOpcode() == ISD::FCOPYSIGN && N0.Val->hasOneUse()) {
SDOperand Tmp = DAG.getNode(ISD::FP_ROUND, VT, N0.getOperand(0), N1);