PNaCl: Check we don't crash in -replace-ptrs-with-ints with odd metadata operands.

test/Transforms/NaCl/replace-ptrs-with-ints.ll

Index: test/Transforms/NaCl/replace-ptrs-with-ints.ll
diff --git a/test/Transforms/NaCl/replace-ptrs-with-ints.ll b/test/Transforms/NaCl/replace-ptrs-with-ints.ll
index 9d2974f4c7f503086f9e550a61f5598d7bada3b4..57186fb0a9f81db7c85976e51cc986a017bae10c 100644
--- a/test/Transforms/NaCl/replace-ptrs-with-ints.ll
+++ b/test/Transforms/NaCl/replace-ptrs-with-ints.ll
@@ -416,6 +416,7 @@ define void @debug_declare(i32 %val) {
 define void @debug_value(i32 %val, i8* %ptr) {
   tail call void @llvm.dbg.value(metadata !{i32 %val}, i64 1, metadata !1, metadata !14)
   tail call void @llvm.dbg.value(metadata !{i8* %ptr}, i64 2, metadata !1, metadata !14)
+  tail call void @llvm.dbg.value(metadata !{i8* null}, i64 2, metadata !1, metadata !14)

[JF, 2015/04/20 23:05:44]

Does this only occur for null values? Or are there other cases that can hit this
bug? I guess clang never emits llvm.dbg.value that's null, but Rust does?

Seems like a good fix, I just want to make sure the test covers all cases.

[Richard Diamond, 2015/04/22 14:04:57]

It was found when building  `rust.pexe`. I'm not sure why, where, etc. It has
never happened before; Rust, as far as I know, doesn't generate it.

What other value types are there to handle? The list includes only Instructions
and Constants, right?

[JF, 2015/04/22 17:48:29]

I was thinking about undef too. Doesn't make much sense, but then again neither
does null ;-)

   ret void
 }
 ; CHECK: define void @debug_value(i32 %val, i32 %ptr) {