[clang] Add GCC-compatible code model names for sparc64

This adds GCC-compatible names for code model selection on 64-bit SPARC
with absolute code.
Testing with a 2-stage build then running codegen tests works okay under
all of the supported code models.

(32-bit target does not have selectable code models)

Reviewed By: @brad0, @MaskRay

(cherry picked from commit b0f0bab)

clang/lib/Driver/ToolChains/Clang.cpp

@@ -5779,6 +5779,14 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       // NVPTX/AMDGPU does not care about the code model and will accept
       // whatever works for the host.
       Ok = true;
+    } else if (Triple.isSPARC64()) {
+      if (CM == "medlow")
+        CM = "small";
+      else if (CM == "medmid")
+        CM = "medium";
+      else if (CM == "medany")
+        CM = "large";
+      Ok = CM == "small" || CM == "medium" || CM == "large";
     }
     if (Ok) {
       CmdArgs.push_back(Args.MakeArgString("-mcmodel=" + CM));

clang/test/Driver/sparc64-codemodel.c

@@ -0,0 +1,6 @@
+// RUN: %clang --target=sparc64 -mcmodel=medlow %s -### 2>&1 | FileCheck -check-prefix=MEDLOW %s
+// RUN: %clang --target=sparc64 -mcmodel=medmid %s -### 2>&1 | FileCheck -check-prefix=MEDMID %s
+// RUN: %clang --target=sparc64 -mcmodel=medany %s -### 2>&1 | FileCheck -check-prefix=MEDANY %s
+// MEDLOW: "-mcmodel=small"
+// MEDMID: "-mcmodel=medium"
+// MEDANY: "-mcmodel=large"