Re: [RFA 5/6] Add validity bits for psymtab high and low fields

[Keith Seitz <keiths@redhat.com>]

On 05/03/2018 03:36 PM, Tom Tromey wrote:
> Right now some psymtab code checks whether a psymtab's textlow or
> texthigh fields are valid by comparing against 0.
> 
> I imagine this is mildly wrong in the current environment, but once
> psymtabs are relocated dynamically, it will no longer be correct,
> because it will be much more normal to see a psymtab with a textlow of
> zero -- this will just mean it appears at the start of the text
> section.
> 

Also wrong if 0 is a valid address! [as a recent patch* serves to remind]

> This patch introduces validity bits to handle this situation more
> nicely, and changes users of the code to follow.
> 
> ChangeLog
> 2018-05-03  Tom Tromey  <tromey@redhat.com>
> 
> 	* dbxread.c (end_psymtab): Use texthigh_valid and textlow_valid.

Does this line not also qualify for texthigh_valid:

  if (PSYMTAB_TEXTHIGH (pst) == 0 && last_function_name
      && gdbarch_sofun_address_maybe_missing (gdbarch))

?

There's also this line in dbx_read_symtab that might qualify (from case N_SCOPE):

	      valu = nlist.n_value + last_function_start;
	      if (PSYMTAB_TEXTHIGH (pst) == 0 || valu > PSYMTAB_TEXTHIGH (pst))
		SET_PSYMTAB_TEXTHIGH (pst, valu);
	      break;

Also in this function, can textlow_not_set be replaced by textlow_valid? [The same with the textlow_not_set parameter to dbx_end_psymtab?]

> 	* mdebugread.c (parse_partial_symbols): Use textlow_valid.
> 	(psymtab_to_symtab_1): Use texthigh_valid and textlow_valid.
> 	* psympriv.h (struct partial_symtab) <textlow_, texthigh_>: Update
> 	comment.
> 	<textlow_valid, texthigh_valid>: New fields.
> 	(set_psymtab_textlow, set_psymtab_texthigh): New inline functions.
> 	(SET_PSYMTAB_TEXTLOW, SET_PSYMTAB_TEXTHIGH): Redefine.
> 	* xcoffread.c (scan_xcoff_symtab): Use textlow_valid.

Otherwise, this all LGTM (IANAM).

Keith

* https://sourceware.org/ml/gdb-patches/2018-05/msg00325.html