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Re: [PATCH] PR rtl-optimization/32219: optimizer causes wrong code in pic/hidden/weak symbol checking


On Tue, Feb 10, 2015 at 1:19 PM, Richard Henderson <rth@redhat.com> wrote:
>> @@ -7445,9 +7465,10 @@ default_elf_asm_output_external (FILE *file ATTRIBUTE_UNUSED,
>>  {
>>    /* We output the name if and only if TREE_SYMBOL_REFERENCED is
>>       set in order to avoid putting out names that are never really
>> -     used. */
>> +     used.   Always output visibility specified in the source.  */
>>    if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))
>> -      && targetm.binds_local_p (decl))
>> +      && (DECL_VISIBILITY_SPECIFIED (decl)
>> +       || targetm.binds_local_p (decl)))
>>      maybe_assemble_visibility (decl);
>
> Explain?
>

This is for the new testcase in my patch:

[hjl@gnu-mic-2 testsuite]$ cat gcc.dg/visibility-23.c
/* PR target/32219 */
/* { dg-do compile } */
/* { dg-require-visibility "" } */
/* { dg-final { scan-hidden "foo" } } */
/* { dg-options "-O2 -fPIC" { target fpic } } */
/* { dg-skip-if "" { "hppa*-*-hpux*" "*-*-aix*" "*-*-darwin*" } "*" { "" } }  */

extern void foo () __attribute__((weak,visibility("hidden")));
int
main()
{
  if (foo)
    foo ();
  return 0;
}
[hjl@gnu-mic-2 testsuite]$

Here targetm.binds_local_p now returns false.  But we must
emit ".hidden foo" even if foo isn't defined in the TU.  Otherwise,
foo wont be hidden if it isn't defined in another TU.


-- 
H.J.


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