Teach DAGCombine to canonicalize the position of a constant in the term operands of an FMA node.

llvm-svn: 157707
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index af61493..647ff6b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5770,6 +5770,10 @@
   if (N1CFP && N1CFP->isExactlyValue(1.0))
     return DAG.getNode(ISD::FADD, N->getDebugLoc(), VT, N0, N2);
 
+  // Canonicalize (fma c, x, y) -> (fma x, c, y)
+  if (!N0CFP && N1CFP)
+    return DAG.getNode(ISD::FMA, N->getDebugLoc(), VT, N1, N0, N2);
+
   return SDValue();
 }