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SubjectRe: [PATCH] ARM: Do not allow unaligned accesses when CONFIG_ALIGNMENT_TRAP
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Hi Andi,

On Thu, 2011-05-26 at 22:10 +0100, Andi Kleen wrote:
>
> > It is possible that -fconserve-stack is still valuable on ARM given that
> > it is also used with -mno-unaligned-access for other things than
> > structure packing on the stack, and therefore its merits can be debated
> > independently from the alignment issue at hand.
>
> The big advantage of -fconserve-stack is that it throttles the inliner
> if the inlining
> would cause too much stack growth. This is something you likely want
> on ARM too, especially as code gets more and more complex.

Do you have any concrete examples of -fconserve-stack giving an overall
win that isn't in the noise? The fact that the GCC documentation
explicitly states that enabling the option can lead to `making the
program slower' does make me question why we're enabling it in the first
place.

>From private conversation, the GCC guys don't seem to think this is a
bug so I'm reluctant to open a bugzilla ticket.

Will



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