On 4/29/19 10:28 AM, Roman Zhuykov wrote:
> Hi, Segher
>
> In pr84524.c we got a loop with an extended inline asm:
> asm volatile ("" : "+r" (v))
> which also gives us a “surprising” situation Alexander predicts.
>
> For sched-deps scanner such volatile asm is a “true barrier”
> > > This code was added in 1997 (r14770). In 2004 the documentation was
> > > changed to clarify how things really work (r88999):
> > >
> > > "Note that even a volatile @code{asm} instruction can be moved relative to
> > > other code, including across jump instructions."
> > >
> > > (followed
Hi!
On Mon, Apr 29, 2019 at 07:28:12PM +0300, Roman Zhuykov wrote:
> > This code was added in 1997 (r14770). In 2004 the documentation was
> > changed to clarify how things really work (r88999):
> >
> > "Note that even a volatile @code{asm} instruction can be moved relative to
> > other code,
Hi, Segher
> > > > In pr84524.c we got a loop with an extended inline asm:
> > > > asm volatile ("" : "+r" (v))
> > > > which also gives us a “surprising” situation Alexander predicts.
> > > >
> > > > For sched-deps scanner such volatile asm is a “true barrier” and we
> > > > create dependencies
Hi Roman,
On Mon, Apr 22, 2019 at 07:36:40PM +0300, Roman Zhuykov wrote:
> > > In pr84524.c we got a loop with an extended inline asm:
> > > asm volatile ("" : "+r" (v))
> > > which also gives us a “surprising” situation Alexander predicts.
> > >
> > > For sched-deps scanner such volatile asm is
> > This issue unfortunately was not solved correctly. In that example we
> > don’t have -fmodulo-sched-allow-regmoves enabled and we should not
> > create any register moves at all.
>
> Yes, but if we do for whatever reason, we should never create register
> moves of hard registers. Because
On Tue, Apr 16, 2019 at 03:08:23PM +0300, Roman Zhuykov wrote:
> This issue unfortunately was not solved correctly. In that example we
> don’t have -fmodulo-sched-allow-regmoves enabled and we should not
> create any register moves at all.
Yes, but if we do for whatever reason, we should never
This issue unfortunately was not solved correctly. In that example we
don’t have -fmodulo-sched-allow-regmoves enabled and we should not
create any register moves at all.
I’ll describe here everything I found while looking on the issue. At
the first step I have patched trunk compiler like
