Lauro, what's the semantics of protected visibility? How it should be
codegen'ed? There were some bits reserved to "future visibility types", so the
only non-trivial part should be codegen.

I don't know what is its semantics, but the codegen must emit ".protected bar".

Mine. Should be trivial.

documentation:
http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Function-Attributes.html

LLVM-side patch
Lauro, please find LLVM-side patch attached. There is no linker part, you'll
have to add it by yourself. llvm-gcc part should be easy, I think (check for
VISIBILITY_PROTECTED in the same places as hidden is checked). LangRef should
be updated with the correct semantics of protected visibility as well.

Testcase:

@​X = protected global i32 1234

The patch looks fine, please apply it. The critical missing pieces are LangRef.html and linker support.

-Chris

Implemented in:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070423/048685.html
...
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070423/048693.html

LangRef.html was also updated, so the only missed part is Linker.

As for linker: ld doesn't allow multiple definitions of the same variable with
different visibility styles. It just treats this as redefinition. Should we
follow ld?

Yes, we should emulate ld

Linking was done in
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070423/048711.html

LLVM-GCC-side patch

LLVM-GCC-side patch
I missed a TREE_PUBLIC check in the previous patch.

Patch applied, should this be closed?

Yes. Definitely.