[Bug middle-end/28862] [4.0/4.1/4.2 Regression] attribute ((aligned)) ignored on vector variables

[uweigand at gcc dot gnu dot org]

------- Comment #7 from uweigand at gcc dot gnu dot org  2006-09-05 12:47 -------
(In reply to comment #5)
> Is this also supposed to fix the problem I posted in comment #2? I applied that
> patch to my gcc but it didn't fix the generated code for me. It's just weird
> because the bug only appears if the code is complex enough. If it's just a
> rather simple function, the generated code is correct.

No, your problem is certainly something completely different.  In fact I've
never seen GCC (common code) do anything even remotely like:
>GCC reserves an area big enough to hold the structure plus padding,
>so it can align the structure dynamically at runtime. It stores a
>pointer to the reserved area and a pointer to the structure within
>the area. 

Normally, attribute ((aligned)) does not cause any code to be
generated that attempts to dynamically adjust alignment at runtime,
it simply allows a variable to be aligned up to whatever default
stack frame alignment the platform ABI provides for.

It appears that the i386 back-end has some special code related to
the -mstackrealign option that may be involved here.  In any case,
this would be something for an i386 back-end person to look into.

Since this is a completely unrelated problem, I recommend you open
a separate bugzilla for it.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28862