Re: display word wrapping

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 30 May 2004 03:38:48 +0200
> From: Juanma Barranquero <lektu@mi.madritel.es>
> 
> I can make it work fine (for all kinds of graphics) by disabling -Og for
> just two functions: `lookup_image' and `png_read_from_memory'.
> 
> On most debugging sessions, lookup_image fails while calling
> image_spec_value or postprocess_image, because img->spec is no longer
> valid (somewhere, img->spec is overwritten). But something's afoul,
> because inserting debugging code into lookup_image makes it fail in
> different ways (for example, failing to load the image). Either the
> optimization is doing something very wrong, or an undetected bug is
> causing data corruption, I'd say.
> 
> Ideas?

Does it crash (it _is_ a crash, isn't it?) under a debugger, or does
that, too, cause the bug to change its behavior?

If the former, run an unmodified optimized code under a debugger and
use debugger facilities instead of debugging code to see what's wrong.

Comparison of machine code in the optimized and unoptimized versions
might also tell you something useful.

Finally, assuming that we are talking about a crash, posting the
detailed description of the crash (exception number, register dump,
stack dump, etc.) here could give some further ideas.