[clang][XCOFF] Indicate that XCOFF does not support COMDATs

Summary: XCOFF doesn't support COMDATs, so clang shouldn't emit them.

Reviewers: stevewan, sfertile, Xiangling_L

Reviewed By: sfertile

Subscribers: dschuff, aheejin, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D74631
diff --git a/clang/test/CodeGen/xcoff-comdat.cpp b/clang/test/CodeGen/xcoff-comdat.cpp
new file mode 100644
index 0000000..7da8d9a
--- /dev/null
+++ b/clang/test/CodeGen/xcoff-comdat.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple powerpc-ibm-aix -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix -emit-llvm -o - %s | FileCheck %s
+
+class a {
+  virtual void d() {}
+  virtual void e();
+};
+void a::e() {}
+
+// CHECK-NOT: = comdat