Author: lattner
Date: Thu Jan 24 00:45:35 2008
New Revision: 46304
URL: http://llvm.org/viewvc/llvm-project?rev=46304&view=rev
Log:
fold fp_round(fp_round(x)) -> fp_round(x).
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=46304&r1=46303&r2=46304&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Jan 24 00:45:35 2008
@@ -3648,6 +3648,15 @@
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);
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