Re: [PATCH] bfd: stop over-allocating aux entries for COFF section symbols

пт, 21 авг. 2026 г. в 14:00, Jan Beulich <[email protected]>:
>
> On 20.08.2026 21:29, Oleg Tolmatcev wrote:
> > coff_new_section_hook allocated ten combined_entry_type slots for every
> > section symbol, behind a comment conceding that the ten was a guess and
> > should not be a constant.  Nothing in BFD sets n_numaux above 1 on a
> > section symbol, and nothing indexes the array past native[1], so eight
> > of the ten were never touched on any target.
> >
> > This runs once per input section, so it significantly reduces peak
> > memory usage.
> >
> > bfd/
> >       * coffcode.h (coff_new_section_hook): Allocate one syment plus
> >       one aux entry rather than ten.
> >
> > Signed-off-by: Oleg Tolmatcev <[email protected]>
>
> Fundamentally okay, one comment though:
>
> > --- a/bfd/coffcode.h
> > +++ b/bfd/coffcode.h
> > @@ -1831,9 +1831,9 @@ coff_new_section_hook (bfd * abfd, asection * section)
> >    /* Allocate aux records for section symbols, to store size and
> >       related info.
> >
> > -     @@ The 10 is a guess at a plausible maximum number of aux entries
> > -     (but shouldn't be a constant).  */
> > -  amt = sizeof (combined_entry_type) * 10;
> > +     One syment plus one aux: nothing sets n_numaux above 1 on a
> > +     section symbol, or indexes this array past native[1].  */
> > +  amt = sizeof (combined_entry_type) * 2;
> >    native = (combined_entry_type *) bfd_zalloc (abfd, amt);
> >    if (native == NULL)
> >      return false;
>
> sizeof(<type>) is generally at risk of going out of sync with the type
> of the variable that is really meant to be used. Since you're already
> touching that line, may I suggest to switch to
>
>   amt = sizeof (*native) * 2;
>
> ? Again - if that's okay with you, I can replace the piece of code while
> committing.
>
> Jan

I am of course okay with it. Thank you.

Oleg