[PATCH] DAGCombine: constant fold FMA

[Mehdi AMINI]

Fix precision :)


http://reviews.llvm.org/D6912

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6955,7 +6955,11 @@
   if (isa<ConstantFPSDNode>(N0) &&
       isa<ConstantFPSDNode>(N1) &&
       isa<ConstantFPSDNode>(N2)) {
-    return DAG.getNode(ISD::FMA, dl, VT, N0, N1, N2);
+    APFloat CstLHS = cast<ConstantFPSDNode>(N0)->getValueAPF();
+    APFloat CstMHS = cast<ConstantFPSDNode>(N1)->getValueAPF();
+    APFloat CstRHS = cast<ConstantFPSDNode>(N2)->getValueAPF();
+    CstLHS.fusedMultiplyAdd(CstMHS, CstRHS, APFloat::rmNearestTiesToEven);
+    return DAG.getConstantFP(CstLHS, VT);
   }
 
   if (DAG.getTarget().Options.UnsafeFPMath) {

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