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

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