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Re: PR7455: What is expected behavior for #pragma weak.
- From: Richard Henderson <rth at redhat dot com>
- To: Steven Bosscher <s dot bosscher at student dot tudelft dot nl>
- Cc: gcc at gcc dot gnu dot org
- Date: Sun, 11 Jan 2004 16:37:47 -0800
- Subject: Re: PR7455: What is expected behavior for #pragma weak.
- References: <200401112326.18067.s.bosscher@student.tudelft.nl>
On Sun, Jan 11, 2004 at 11:26:18PM +0100, Steven Bosscher wrote:
> Hi,
>
> Bug 7455 is a "wrong-code" bug about weak symbols. In the past,
> the following code:
> _____________________________
> #pragma weak bar = foo
> _____________________________
>
> would give:
>
> .file "t.c"
> .version "01.01"
> gcc2_compiled.:
> .weak bar
> .set bar,foo
> .ident "GCC: (GNU) 2.95.4 20011002 (Debian prerelease)"
>
> Newer GCCs do not write the weak symbol:
Correct. The the assembly above is meaningless. It "works" in that it
assembles, but it doesn't do anything useful. One could even argue that
it's a bug that it assembles.
> But this one,
> _____________________________
> extern int bar (void) __attribute__ ((weak));
> _____________________________
>
> gives:
> .file "t.c"
> .section .note.GNU-stack,"",@progbits
> .ident "GCC: (GNU) 3.4.0 20040111 (experimental)"
This is correct as well. Bar should be marked weak if it is used, but
since it is not used there's no need for it to be mentioned at all.
r~