On Wed, Feb 12, 2025 at 1:00 AM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Wed, Feb 12, 2025 at 9:41 AM Andrew Pinski <quic_apin...@quicinc.com>
> wrote:
> >
> > So inline-asm is known not to trap BUT it can have undefined behavior
> > if made executed speculatively. This fixes the loop invariant pass to
> > treat it similarly as trapping cases. If the inline-asm could be executed
> > always, then it will be pulled out of the loop; otherwise it will be kept
> > inside the loop.
> >
> > Bootstrapped and tested on x86_64-linux-gnu.
> >
> > gcc/ChangeLog:
> >
> > * loop-invariant.cc (find_invariant_insn): Treat inline-asm similar
> > to
> > trapping instruction and only move them if always executed.
> >
> > Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> > ---
> > gcc/loop-invariant.cc | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/gcc/loop-invariant.cc b/gcc/loop-invariant.cc
> > index bcb52bb9c76..79a4c39dfb0 100644
> > --- a/gcc/loop-invariant.cc
> > +++ b/gcc/loop-invariant.cc
> > @@ -1123,6 +1123,11 @@ find_invariant_insn (rtx_insn *insn, bool
> > always_reached, bool always_executed)
> > if (may_trap_or_fault_p (PATTERN (insn)) && !always_reached)
> > return;
> >
> > + /* inline-asm that is not always executed cannot be moved
> > + as it might trap. */
>
> as it might conditionally trap?
Yes and I changed the comment to be:
/* inline-asm that is not always executed cannot be moved
as it might conditionally trap. */
And pushed with that change.
Thanks,
Andrew Pinski
>
> OK.
>
> Thanks,
> Richard.
>
> > + if (!always_reached && asm_noperands (PATTERN (insn)) >= 0)
> > + return;
> > +
> > depends_on = BITMAP_ALLOC (NULL);
> > if (!check_dependencies (insn, depends_on))
> > {
> > --
> > 2.43.0
> >
