Add an intrinsic and codegen support for fused multiply-accumulate. The intent
is to use this for architectures that have a native FMA instruction.

llvm-svn: 134742
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f5e4526..349b4d5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5878,6 +5878,7 @@
   case ISD::FSUB:   return "fsub";
   case ISD::FMUL:   return "fmul";
   case ISD::FDIV:   return "fdiv";
+  case ISD::FMA:    return "fma";
   case ISD::FREM:   return "frem";
   case ISD::FCOPYSIGN: return "fcopysign";
   case ISD::FGETSIGN:  return "fgetsign";