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/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 709b84c..f212f24 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -646,6 +646,10 @@
     addLegalFPImmediate(APFloat(-1.0f)); // FLD1/FCHS
   }
 
+  // We don't support FMA.
+  setOperationAction(ISD::FMA, MVT::f64, Expand);
+  setOperationAction(ISD::FMA, MVT::f32, Expand);
+
   // Long double always uses X87.
   if (!UseSoftFloat) {
     addRegisterClass(MVT::f80, X86::RFP80RegisterClass);
@@ -670,6 +674,8 @@
       setOperationAction(ISD::FSIN           , MVT::f80  , Expand);
       setOperationAction(ISD::FCOS           , MVT::f80  , Expand);
     }
+
+    setOperationAction(ISD::FMA, MVT::f80, Expand);
   }
 
   // Always use a library call for pow.