On Tue, Feb 2, 2016 at 5:03 AM, Ilya Enkovich <enkovich....@gmail.com> wrote: > 2016-02-02 15:46 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>: >> On Tue, Feb 2, 2016 at 4:30 AM, H.J. Lu <hjl.to...@gmail.com> wrote: >>> On Tue, Feb 2, 2016 at 4:29 AM, Jakub Jelinek <ja...@redhat.com> wrote: >>>> On Tue, Feb 02, 2016 at 01:24:26PM +0100, Uros Bizjak wrote: >>>>> 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. >>>> >>>> So, is http://gcc.gnu.org/ml/gcc-patches/2016-01/msg02129.html >>>> ok for trunk then (alone or with additional sorry, incremental or not?)? >>>> I believe it does just that. >>> >>> This patch is WRONG. >>> >>> -- >>> H.J. >> >> You will run into the same ICE with >> >> -mincoming-stack-boundary=2 -msse2 -O2 -m32 >> >> in a leaf function which needs DImode spill/fill. > > Why would we need DImode spill/fill having no DImode registers? >
Because STV is enabled with -mincoming-stack-boundary=2 -msse2 -O2 -m32 -- H.J.
