don't fold fp_round(fp_extend(load)) -> fp_round(extload)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45400 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 242fffd..0ee4557 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3672,6 +3672,10 @@
   ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
   MVT::ValueType VT = N->getValueType(0);
   
+  // If this is fp_round(fpextend), don't fold it, allow ourselves to be folded.
+  if (N->hasOneUse() && (*N->use_begin())->getOpcode() == ISD::FP_ROUND)
+    return SDOperand();
+  
   // fold (fp_extend c1fp) -> c1fp
   if (N0CFP && VT != MVT::ppcf128)
     return DAG.getNode(ISD::FP_EXTEND, VT, N0);