Re: The 'cold' function attribute and GDB

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 2 May 2019 08:56:23 -0700
> From: Kevin Buettner <kevinb@redhat.com>
> Cc: gdb-patches@sourceware.org, simark@simark.ca
> 
> >   (gdb) break print.c:1824
> >   Breakpoint 1 at 0x12e1f36: file print.c, line 1824.
> >   (gdb) info line print.c:1824
> >   Line 1824 of "print.c"
> >      starts at address 0x12e1f36 <print_vectorlike.cold.65+593>
> >      and ends at 0x12e1f3b <print_vectorlike.cold.65+598>.
> 
> I'm not especially surprised that GDB chose a nearby minimal symbol to
> print here.  I am surprised at the rather large offsets from that
> symbol, however.  In the example that I studied last year, I think
> that the first offset was 0.

In the full disassembly of print_vectorlike, there are many jumps to
print_vectorlike.cold.65, with different offsets.  The smallest offset
is indeed zero.  So it looks like print_vectorlike.cold.65 is a heap
of all the "cold paths" in print_vectorlike, all of which eventually
lead to emacs_abort.  The direct call to that is just one such path.

Let me know if you need help with building the master branch of Emacs.