bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c

[Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Eli Zaretskii <eliz@gnu.org> writes:

>> From: Pip Cet <pipcet@gmail.com>
>> Date: Sat, 13 Mar 2021 15:45:52 +0000
>> Cc: 47067@debbugs.gnu.org, Andrea Corallo <akrl@sdf.org>
>> 
>> >   (defcustom comp-debug 0
>> >     "Debug level for native compilation, a number between 0 and 3.
>> >   This is intended for debugging the compiler itself.
>> >     0 no debugging output.
>> >       This is the recommended value unless you are debugging the compiler itself.
>> >     1 emit debug symbols and dump pseudo C code.
>> >     2 dump gcc passes and libgccjit log file.
>> >     3 dump libgccjit reproducers."
>> >
>> > The first line is somewhat deceptive, as it doesn't say portions of
>> > the backtrace will be anonymous; the backtrace is useful even if not
>> > "debugging the compiler itself".  And the description of level 1 says
>> > it will also "dump pseudo C code", which I don't think is needed for
>> > most of the debugging.  Maybe we need an intermediate level that just
>> > leaves the symbols without dumping the pseudo code?
>> 
>> I think that's an excellent idea.
>
> Andrea, is it possible to have debug level 1 produce only the debug
> info within the generated code, and leave the pseudo-code dump for
> higher levels?  If you don't have time to implement this yourself, can
> you instruct me what changes need to be made?  I'd like to try
> recompiling everything with debug level 1 and see if that helps with
> the backtraces.

Sure that's very easy (the attached should do the job), is this
something you'd like to have a local modification or a change in the
branch?

If the case is the second before I'd just like to understand why the
Windows toolchain needs debug symbols for function names and if this is
a bug or the expected behavior.

IME this was never the case on systems I've worked on and this is why I
though having debug symbols and dump pseudo C code together in the same
debug level made sense, essentially to allow stepping.

Thanks

  Andrea


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diff --git a/src/comp.c b/src/comp.c
index a79ee4ad87..f295106576 100644
--- a/src/comp.c
+++ b/src/comp.c
@@ -4484,7 +4484,7 @@ DEFUN ("comp--compile-ctxt-to-file", Fcomp__compile_ctxt_to_file,
 
   add_driver_options ();
 
-  if (comp.debug)
+  if (comp.debug > 1)
       gcc_jit_context_dump_to_file (comp.ctxt,
 				    format_string ("%s.c", SSDATA (ebase_name)),
 				    1);