[llvm-dev] Internal visibility

[Rafik Zurob via llvm-dev]

Hello

In GCC on Linux on Power, -fvisibility=internal enables internal 
visibility.

$ cat t.c
int foo(int i) { return i + 1; }
$ gcc t.c -c -fvisibility=internal
$ readelf -s t.o | grep foo
     8: 0000000000000000    60 FUNC    GLOBAL INTERNAL    1 foo
$

But in Clang/LLVM, GlobalValue::VisibilityTypes does not have internal 
visibility:

  /// An enumeration for the kinds of visibility of global values.
  enum VisibilityTypes {
    DefaultVisibility = 0,  ///< The GV is visible
    HiddenVisibility,       ///< The GV is hidden
    ProtectedVisibility     ///< The GV is protected
  };

and using -fvisibility=internal in Clang uses the 
close-but-not-quite-the-same hidden visibility:

$ clang t.c -c -fvisibility=internal
$ readelf -s t.o | grep foo
     2: 0000000000000000    36 FUNC    GLOBAL HIDDEN     2 foo
$

Given that -fvisibility=internal is accepted, I assume this behaviour is 
intentional.  Can anyone help me understand why that is, or point me to 
where I can find out more?

Thanks

Rafik