Re: [PATCH] Add name_of_main and language_of_main to the DWARF index

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Matheus Branco Borella <dark.ryu.550@gmail.com>
> Date: Fri, 30 Jun 2023 17:36:43 -0300
> From: Matheus Branco Borella via Gdb-patches <gdb-patches@sourceware.org>
> 
> Alright, this one should incorporate all of the changes you suggested. And, now
> that I've sorted out my copyright assignment, this should be good to go now?
> Unless I missed something.

Your assignment is not on file yet, AFAICT.  Was the paperwork
completed, i.e. did you get a copy of the assignment signed by you and
by the FSF?  If not, you need to wait some more.

> This patch adds a new section to the DWARF index containing the name
> and the language of the main function symbol, gathered from
> `cooked_index::get_main`, if available. Currently, for lack of a better name,
> this section is called the "shortcut table". The way this name is both saved and 
> applied upon an index being loaded in mirrors how it is done in 
> `cooked_index_functions`, more specifically, the full name of the main function 
> symbol is saved and `set_objfile_main_name` is used to apply it after it is 
> loaded.
> 
> The main use case for this patch is in improving startup times when dealing with
> large binaries. Currently, when an index is used, GDB has to expand symtabs
> until it finds out what the language of the main function symbol is. For some
> large executables, this may take a considerable amount of time to complete,
> slowing down startup. This patch bypasses that operation by having both the name
> and language of the main function symbol be provided ahead of time by the index.
> 
> In my testing (a binary with about 1.8GB worth of DWARF data) this change brings
> startup time down from about 34 seconds to about 1.5 seconds.
> ---
>  gdb/NEWS                    |  2 ++
>  gdb/doc/gdb.texinfo         | 23 +++++++++++++--
>  gdb/dwarf2/index-write.c    | 47 +++++++++++++++++++++++++++----
>  gdb/dwarf2/read-gdb-index.c | 56 +++++++++++++++++++++++++++++++++++--
>  gdb/dwarf2/read.c           | 13 +++++++--
>  gdb/dwarf2/read.h           | 12 ++++++++
>  6 files changed, 142 insertions(+), 11 deletions(-)

Thanks.  The documentation parts are OK, but please fix the text to
leave two spaces between sentences, not one.

Reviewed-By: Eli Zaretskii <eliz@gnu.org>