Susprising behavior of gcc on x86 (-m32)

[Mathieu Malaterre]

On Tue, Sep 8, 2015 at 11:45 AM, Andrew Haley <aph@redhat.com> wrote:
> On 09/08/2015 10:15 AM, Mathieu Malaterre wrote:
>> What is even more surprising is that I can no longer reproduce the
>> behavior using `valgrind` from my 32bits chroot.
>>
>> I understand that my bug description is relatively small, but I am
>> eager to report a more specific gcc issue. If anyone could help me
>> narrow down this issue, I'd appreciate your comments.
>>
>> Please note that that I disabled any kind of optimizations by using
>> (explicitly!) -O0.
>
> I'm guessing that it's some silliness with the FPU, but that's a wild
> guess.

Technically this code path is *not* using floating point at all (by
JPEG 2000 reversible kernel design). integer based shift&additions
operations only.

> You first need to find out what part of the file is different, and
> narrow it down from there.  One question: how well do you understand
> the OpenJPEG code base?

Let me answer it this way: this is a huge task -for me- to narrow down
this issue to a minimal C code.