pass_stdarg problem when run after pass_lim

[Jakub Jelinek]

On Thu, Jan 29, 2015 at 07:44:29PM +0100, Richard Biener wrote:
> On January 29, 2015 6:25:35 PM CET, Jakub Jelinek <jakub@redhat.com> wrote:
> >On Thu, Jan 29, 2015 at 06:19:45PM +0100, Tom de Vries wrote:
> >> consider attached patch, which adds pass_lim after fre1 (a
> >simplification of
> >> my oacc kernels patch series).
> >> 
> >> The included testcase lim-before-stdarg.c fails.
> >> 
> >> The first sign of trouble is in lim-before-stdarg.c.088t.stdarg
> >(attached):
> >> ...
> >> gen_rtvec: va_list escapes 0, needs to save 0 GPR units and 0 FPR
> >units.
> >> ...
> >> 
> >> Because of the 'need to save 0 GPRs units', at expand no prologue is
> >> generated to dump the varargs in registers onto stack.
> >
> >The stdarg pass can't grok too heavy optimizations, so if at all
> >possible,
> >don't schedule such passes early, and if you for some reason do, avoid
> >optimizing in there the va_list related accesses.  I'm afraid that is
> >the
> >only recommendation I can give here for that.
> 
> The other possibility (Matz has patches for that) is to delay vaarg lowering currently done by gimplification and combine it with the stdarg pass.

Yeah, that should work too.  But stage1 material probably.

	Jakub