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Re: New option to turn off stack reuse for temporaries
On Fri, Jun 22, 2012 at 11:29 AM, Jason Merrill <jason@redhat.com> wrote:
> On 06/22/2012 01:30 AM, Richard Guenther wrote:
>>>
>>> What other issues? It enables more potential code motion, but on the
>>> other hand, causes more conservative stack reuse. As far I can tell,
>>> the handling of temporaries is added independently after the clobber
>>> for scoped variables are introduced. This option can be used to
>>> restore the older behavior (in handling temps).
>>
>>
>> Well, it does not really restore the old behavior (if you mean before
>> adding
>> CLOBBERS, not before the single patch that might have used those for
>> gimplifying WITH_CLEANUP_EXPR). ?You say it disables stack-slot sharing
>> for those decls but it also does other things via side-effects of no
>> longer
>> emitting the CLOBBER. ?I say it's better to disable the stack-slot
>> sharing.
>
>
> The patch exactly restores the behavior of temporaries from before my change
> to add CLOBBERs for temporaries. ?The primary effect of that change was to
> provide stack-slot sharing, but if there are other effects they are probably
> desirable as well, since the broken code depended on the old behavior.
So you see it as workaround option, like -fno-strict-aliasing, rather than
debugging aid?
Richard.
> Jason