AMDGPU: Add Vega12 and Vega20

Changes by
  Matt Arsenault
  Konstantin Zhuravlyov

llvm-svn: 331216
diff --git a/clang/lib/Basic/Targets/AMDGPU.cpp b/clang/lib/Basic/Targets/AMDGPU.cpp
index d956d13..b6b9aa2 100644
--- a/clang/lib/Basic/Targets/AMDGPU.cpp
+++ b/clang/lib/Basic/Targets/AMDGPU.cpp
@@ -133,6 +133,10 @@
       CPU = "gfx600";
 
     switch (parseAMDGCNName(CPU).Kind) {
+    case GK_GFX906:
+      Features["dl-insts"] = true;
+      LLVM_FALLTHROUGH;
+    case GK_GFX904:
     case GK_GFX902:
     case GK_GFX900:
       Features["gfx9-insts"] = true;