[AMDGPU] Add llvm.amdgcn.fmad.ftz intrinsic

This intrinsic selects v_mad_f32 regardless of fp32 denorm support.

Differential Revision: https://reviews.llvm.org/D48573

llvm-svn: 335654
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index b8e6c11..e6b3bd1 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -4922,6 +4922,9 @@
     return SDValue(DAG.getMachineNode(AMDGPU::WWM, DL, Src.getValueType(), Src),
                    0);
   }
+  case Intrinsic::amdgcn_fmad_ftz:
+    return DAG.getNode(AMDGPUISD::FMAD_FTZ, DL, VT, Op.getOperand(1),
+                       Op.getOperand(2), Op.getOperand(3));
   default:
     if (const AMDGPU::ImageDimIntrinsicInfo *ImageDimIntr =
             AMDGPU::getImageDimIntrinsicInfo(IntrinsicID))