[cfe-commits] Alignment of return from __builtin_alloca

[Eli Friedman]

On Thu, Jun 7, 2012 at 3:20 PM, Chandler Carruth <chandlerc at google.com> wrote:
> On Thu, Jun 7, 2012 at 3:08 PM, David Sehr <sehr at google.com> wrote:
>>
>> Please disregard my last comment.  Implementing that will be a bit
>> challenging, as stackAlign is a back end value rather than a clang
>> TargetInfo value. Are there targets where stackAlign < SuitableAlign?
>
>
> I suspect so, and that's worrisome...
>
> I'm not intimately familiar with stack alignment and Joerg's concerns, but
> it seems like a *more* aligned alloca would be fine, but a less aligned
> alloca would be bad. Why is it a bad thing to increase the alignment to
> SuitableAlign?

It would probably be surprising if __builtin_alloca triggered stack
realignment...

-Eli