On Mon, Nov 29, 2021 at 11:56 PM Qing Zhao <qing.z...@oracle.com> wrote:
>
> Peter,
>
> Thanks a lot for the patch.
>
> Richard, how do you think of the patch?
>
> (The major concern for me is:
>
> With the current patch proposed by Peter, we will generate the call
> to .DEFERRED_INIT for a variable with OPAQUE_TYPE during gimplification phase,
> However, if this variable is in register, then the call to
> .DEFERRED_INIT will NOT be expanded during RTL expansion phase. This
> unexpanded call to .DEFERRED_INIT might cause some potential IR issue later?
I think that's inconsistent indeed. Peter, what are "opaque"
registers? rs6000-modes.def suggests
that there's __vector_pair and __vector_quad, what's the GIMPLE types
for those? It seems they
are either SSA names or expanded to pseudo registers but there's no
constants for them.
>
> If the above is a real issue, should we skip initialization for all
> OPAQUE_TYPE variables even when they are in memory and can be initialized
> with memset?
> then we should update “is_var_need_auto_init” in gimplify.c
> instead. However, the issue with this approach is, we might miss the
> opportunity to initialize an OPAQUE_TYPE variable if it will be in memory?
> ).
I think we need to bite the bullet at some point to do register initialization
not via expand_assignment but directly based on what the LHS expands to.
Can they be initialized? I see they can be copied at least.
If such "things" cannot be initialized they should indeed be exempt
from auto-init. The
documentation suggests that they act as bit-bucked but even bit-buckets should
be initializable, thus why exactly does CONST0_RTX not exist for them?
Richard.
>
> Thanks.
>
> Qing
>
>
> > On Nov 29, 2021, at 3:56 PM, Peter Bergner <berg...@linux.ibm.com> wrote:
> >
> > Sorry for dropping the ball on testing the patch from the bugzilla!
> >
> > The following patch fixes the ICE reported in the bugzilla on the
> > pre-existing
> > gcc testsuite test case, bootstraps and shows no testsuite regressions
> > on powerpc64le-linux. Ok for trunk?
> >
> > Peter
> >
> >
> > For -ftrivial-auto-var-init=*, skip initializing the register variable if it
> > is an opaque type, because CONST0_RTX(mode) is not defined for opaque modes.
> >
> > gcc/
> > PR middle-end/103127
> > * internal-fn.c (expand_DEFERRED_INIT): Skip if VAR_TYPE is opaque.
> >
> > diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
> > index 0cba95411a6..7cc0e9d5293 100644
> > --- a/gcc/internal-fn.c
> > +++ b/gcc/internal-fn.c
> > @@ -3070,6 +3070,10 @@ expand_DEFERRED_INIT (internal_fn, gcall *stmt)
> > }
> > else
> > {
> > + /* Skip variables of opaque types that are in a register. */
> > + if (OPAQUE_TYPE_P (var_type))
> > + return;
> > +
> > /* If this variable is in a register use expand_assignment.
> > For boolean scalars force zero-init. */
> > tree init;
>
