AMDGPU: Add Vega12 and Vega20

Changes by
  Matt Arsenault
  Konstantin Zhuravlyov

llvm-svn: 331215
diff --git a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
index a346e40..61cbba4 100644
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -100,6 +100,7 @@
 
       case AMDGPU::V_MAC_F32_e64:
       case AMDGPU::V_MAC_F16_e64:
+      case AMDGPU::V_FMAC_F32_e64:
         if (!isVGPR(Src2, TRI, MRI) ||
             TII->hasModifiersSet(MI, AMDGPU::OpName::src2_modifiers))
           return false;