ld-related bug in LTTng

[Alan Modra]

On Fri, May 02, 2014 at 03:40:10PM -0700, Martin Ãœnsal wrote:
> On Thu, May 1, 2014 at 4:23 PM, Alan Modra <amodra@gmail.com> wrote:
> > Is gcc emitting the reference to __start___tracepoints_ptrs as hidden?
> > (Look at an object with readelf -s to see)
> 
> Aha! No, it isn't.
> 
> With GCC 4.6.4 the symbol is correctly emitted as hidden visibility:
> 
> $ arm-linux-gnueabi-readelf -s pmtrace_bundle_provider.o | grep __start_
>    153: 00000000     0 NOTYPE  WEAK   HIDDEN   UND __start___tracepoints_ptr
> 
> With GCC 4.7.2 the symbol is incorrectly emitted as default visibility:
> 
> $ arm-linux-gnueabi-readelf -s pmtrace_bundle_provider.o | grep __start_
>    144: 00000000     0 NOTYPE  WEAK   DEFAULT  UND __start___tracepoints_ptr
> 
> Here is the declaration:
> 
> extern struct tracepoint * const __start___tracepoints_ptrs[]
> __attribute__((weak, visibility("hidden")));
> 
> This looks like it is clearly a compiler issue. I will take this back
> to gcc-help mailing list.

It might be worth checking the assembly output, to rule out as
assembler issue.  gcc -S with

extern void *const x __attribute__ ((weak, visibility ("hidden")));
void *const foo (void) { return x; }

on my powerpc 4.7.2 compiler emits
...
	.weak	x
	.hidden	x

-- 
Alan Modra
Australia Development Lab, IBM