Check for metadata in PNaCl ABI checker.

test/NaCl/PNaClABI/types.ll

 ; RUN: pnacl-abicheck < %s | FileCheck %s
+; RUN: pnacl-abicheck -allow-debug-metadata < %s | FileCheck %s --check-prefix=DEBUG
 ; Test types allowed by PNaCl ABI
 
 ; Basic global types
 
 ; TODO(mseaborn): Re-enable integer size checking.
 ; See https://code.google.com/p/nativeclient/issues/detail?id=3360
 ; C;HECK: Variable i4 has disallowed type: i4
 ;@i4 = private global i4 0
 ; C;HECK: Variable i33 has disallowed type: i33
 ;@i33 = private global i33 0
@@ skipping 93 matching lines @@
 @alias1 = alias i32* @i32
 
 ; CHECK: Function badReturn has disallowed return type
 declare half* @badReturn()
 
 ; CHECK: Function badArgType1 argument 1 has disallowed type
 declare void @badArgType1(half %a, i32 %b)
 ; CHECK: Function badArgType2 argument 2 has disallowed type
 declare void @badArgType2(i32 %a, half %b)
 
-; CHECK: Named metadata node namedmd refers to disallowed type
+; If the metadata is allowed we want to check for types.
+; We have a hacky way to test this. The -allow-debug-metadata whitelists debug
+; metadata.  That allows us to check types within debug metadata, even though
+; debug metadata normally does not have illegal types.
+; DEBUG-NOT: Named metadata node llvm.dbg.cu is disallowed
+; DEBUG: Named metadata node llvm.dbg.cu refers to disallowed type: half
+; CHECK: Named metadata node llvm.dbg.cu is disallowed
+!llvm.dbg.cu = !{!0}
 !0 = metadata !{ half 0.0}
-!namedmd = !{!0}
+
+; CHECK: Named metadata node madeup is disallowed
+; DEBUG: Named metadata node madeup is disallowed
+!madeup = !{!1}
+!1 = metadata !{ half 1.0}