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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134742 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 2afec33..3c8b04f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4651,6 +4651,13 @@
   case Intrinsic::pow:
     visitPow(I);
     return 0;
+  case Intrinsic::fma:
+    setValue(&I, DAG.getNode(ISD::FMA, dl,
+                             getValue(I.getArgOperand(0)).getValueType(),
+                             getValue(I.getArgOperand(0)),
+                             getValue(I.getArgOperand(1)),
+                             getValue(I.getArgOperand(2))));
+    return 0;
   case Intrinsic::convert_to_fp16:
     setValue(&I, DAG.getNode(ISD::FP32_TO_FP16, dl,
                              MVT::i16, getValue(I.getArgOperand(0))));