[clang][tests][NFC] Add filescope array initialization test

[cebowleratibm]

Summary

This test is based on a customer-reported failure in an XL compiler, added here to improve clang regression testing. The primary purpose of the test is to ensure that the array initializations can be evaluated without the need for runtime initialization.

[AaronLiu]

LGTM. Thanks!

clang/test/CodeGen/array-init-2.c

+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
+
+typedef enum {
+   a,
+   b,
+   c,
+   d,
+   e,
+   f,
+   g,
+   h
+} E;
+
+typedef struct {
+   E c;
+   int val;
+} Entry;
+
+static const Entry entries[] = {
+   {a,},
+   {b,},
+   {c,},
+   {d,},
+   {e,},
+   {f,},
+   {g,},
+   {h,}
+};
+
+const Entry *list[] = {
+   entries,
+   entries,
+   entries
+};
+
+// CHECK: %struct.Entry = type { [[E:i[0-9]+]], i32 }
+// CHECK: @entries = internal constant [8 x %struct.Entry] [%struct.Entry zeroinitializer, %struct.Entry { [[E]] 1, i32 0 }, %struct.Entry { [[E]] 2, i32 0 }, %struct.Entry { [[E]] 3, i32 0 }, %struct.Entry { [[E]] 4, i32 0 }, %struct.Entry { [[E]] 5, i32 0 }, %struct.Entry { [[E]] 6, i32 0 }, %struct.Entry { [[E]] 7, i32 0 }], align 4
+// CHECK: @list = global [3 x %struct.Entry*] [%struct.Entry* getelementptr inbounds ([8 x %struct.Entry], [8 x %struct.Entry]* @entries, i32 0, i32 0), %struct.Entry* getelementptr inbounds ([8 x %struct.Entry], [8 x %struct.Entry]* @entries, i32 0, i32 0), %struct.Entry* getelementptr inbounds ([8 x %struct.Entry], [8 x %struct.Entry]* @entries, i32 0, i32 0)], align 8