On Tue, Feb 2, 2016 at 12:53 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>> The bottom line is ix86_minimum_alignment must return the correct >> number for DImode or you can just turn off STV. My suggestion is >> to use my patch. > > Uros, any preferences here? I mean, it is possible to use > e.g. the ix86_option_override_internal and have H.J's ix86_minimum_alignment > change as a safety net, in the usual case for -mpreferred-stack-boundary=2 > we'll just disable TARGET_STV and ix86_minimum_alignment change won't do > anything, as TARGET_STV will be false, and if for whatever case it gets > through (target attribute, -mincoming-stack-boundary=, ...) > ix86_minimum_alignment will be there to ensure enough stack alignment. > Most of the smaller -mpreferred-stack-boundary= uses are -mno-sse anyway, > and that is something we don't want to affect. IMO, we should disable STV when -mpreferred-stack-boundary < 3, as STV is only an optimization. Perhaps we can also emit a "sorry" for explicit -mstv in case stack boundary requirement is not satisfied. *If* there is a need for -mstv with smaller stack boundary, we can revisit this decision for later gcc versions. I think disabling STV is less surprising option than increasing stack boundary behind the user's back. Uros.
