[Bug target/82248] probe_stack can generate unpredictable STR on arm

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82248

--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> ---
On Thu, 23 Nov 2017, ramana at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82248
> 
> --- Comment #3 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> ---
> (In reply to Richard Biener from comment #2)
> > Miscompiles mpfr for us on armv7.  Isn't it easy enough to handle this in
> > the insn pattern by using some non pre/post-indexed memory_operand predicate
> > and or using an early clobbered match_scratch to allocate 'r0'?
> 
> 
> I was testing a patch that used 'o' instead of 'm' in the constraint as that's
> just an offsettable address and would prevent post/ pre-inc type operations but
> it slipped through  the cracks with travels in September :( 
> 
> Can you test if that is sufficient for you or what's the runes in configure for
> forcing probe_stack_range ? 

Seems to work fine.

Richard.