PNaCl: Fix ExpandCtors to handle an empty list case

test/Transforms/NaCl/expand-ctors-emptylist.ll

Index: test/Transforms/NaCl/expand-ctors-emptylist.ll
diff --git a/test/Transforms/NaCl/expand-ctors-emptylist.ll b/test/Transforms/NaCl/expand-ctors-emptylist.ll
new file mode 100644
index 0000000000000000000000000000000000000000..6ab68852b9d342b706e318b9b2187abc6e2a2af2
--- /dev/null
+++ b/test/Transforms/NaCl/expand-ctors-emptylist.ll
@@ -0,0 +1,13 @@
+; RUN: opt %s -nacl-expand-ctors -S | FileCheck %s -check-prefix=NO_CTORS

[jvoung (off chromium), 2013/05/22 15:47:21]

Why two separate RUN invocations?  Can't you just combine them?

[Mark Seaborn, 2013/05/22 16:30:38]

It makes the test stricter.  Many other tests do this.

"CHECK-NOT: foo" only asserts that "foo" doesn't appear between the two
enclosing CHECKs within a given FileCheck invocation.  Putting the CHECK-NOTs in
their own FileCheck invocation ensures that the strings don't appear anywhere in
the output.

[jvoung (off chromium), 2013/05/22 16:50:40]

Ah, right...

+; NO_CTORS-NOT: __init_array_end
+; NO_CTORS-NOT: __fini_array_end
+; NO_CTORS-NOT: llvm.global_ctors
+
+; RUN: opt %s -nacl-expand-ctors -S | FileCheck %s
+
+; Check that the pass works when the initializer is "[]", which gets
+; converted into "undef" by the reader.
+@llvm.global_ctors = appending global [0 x { i32, void ()* }] []
+
+; CHECK: @__init_array_start = internal constant [0 x void ()*] zeroinitializer
+; CHECK: @__fini_array_start = internal constant [0 x void ()*] zeroinitializer