On Mon, Sep 13, 2021 at 1:14 PM Hongtao Liu <crazy...@gmail.com> wrote:
>
> On Mon, Sep 13, 2021 at 5:15 PM Richard Biener
> <richard.guent...@gmail.com> wrote:
> >
> > On Mon, Sep 13, 2021 at 8:26 AM Hongtao Liu <crazy...@gmail.com> wrote:
> > >
> > > On Mon, Sep 13, 2021 at 2:11 PM Richard Biener via Gcc-patches
> > > <gcc-patches@gcc.gnu.org> wrote:
> > > >
> > > > On Fri, Sep 10, 2021 at 2:58 PM liuhongt <hongtao....@intel.com> wrote:
> > > > >
> > > > > gcc/ChangeLog:
> > > > >
> > > > > * expmed.c (extract_bit_field_using_extv): validate_subreg
> > > > > before call gen_lowpart.
> > > > > ---
> > > > > gcc/expmed.c | 6 +++++-
> > > > > 1 file changed, 5 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/gcc/expmed.c b/gcc/expmed.c
> > > > > index 3143f38e057..10d62d857a8 100644
> > > > > --- a/gcc/expmed.c
> > > > > +++ b/gcc/expmed.c
> > > > > @@ -1571,12 +1571,16 @@ extract_bit_field_using_extv (const
> > > > > extraction_insn *extv, rtx op0,
> > > > >
> > > > > if (GET_MODE (target) != ext_mode)
> > > > > {
> > > > > + machine_mode tmode = GET_MODE (target);
> > > > > /* Don't use LHS paradoxical subreg if explicit truncation is
> > > > > needed
> > > > > between the mode of the extraction (word_mode) and the target
> > > > > mode. Instead, create a temporary and use convert_move to
> > > > > set
> > > > > the target. */
> > > > > if (REG_P (target)
> > > > > - && TRULY_NOOP_TRUNCATION_MODES_P (GET_MODE (target),
> > > > > ext_mode))
> > > > > + && TRULY_NOOP_TRUNCATION_MODES_P (tmode, ext_mode)
> > > > > + && validate_subreg (ext_mode, tmode,
> > > > > + target,
> > > > > + subreg_lowpart_offset (ext_mode,
> > > > > tmode)))
> > > > > {
> > > > > target = gen_lowpart (ext_mode, target);
> > > >
> > > > That would be equivalent to use gen_lowpart_if_possible?
> > > No, target will be changed to NULL_RTX.
> > > But it does avoid ICE since maybe_expand_insn can legitimate operands,
> > > but I doubt it will introduce other bugs since the target has been
> > > changed here.
> > >
> > > I think the validate_subreg solution is plain and straightforward,
> > > just like it's done in
> > > r11-7515-g0ad6de3883a1641f7ec0bd9cf56d41fa5b313dae.
> >
> > That guards an explicit gen_rtx_SUBREG, here we're using gen_lowpart.
> > It's not an obvious match to validate gen_lowpart with validate_subreg,
> > I thought that gen_lowpart_if_possible would be prefered. You obviously
> > have to adjust the code, like
> >
> > rtx tem;
> > if (...
> > && (tem = gen_lowpart_if_possible (ext_mode, target))
> > {
> Yes, update patch
>
> bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
> Ok for trunk?
OK.
Thanks,
Richard.
> gcc/ChangeLog:
>
> * expmed.c (extract_bit_field_using_extv): Use
> gen_lowpart_if_possible instead of gen_lowpart to avoid ICE.
> ---
> gcc/expmed.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/expmed.c b/gcc/expmed.c
> index 3143f38e057..59734d4841c 100644
> --- a/gcc/expmed.c
> +++ b/gcc/expmed.c
> @@ -1571,14 +1571,16 @@ extract_bit_field_using_extv (const
> extraction_insn *extv, rtx op0,
>
> if (GET_MODE (target) != ext_mode)
> {
> + rtx temp;
> /* Don't use LHS paradoxical subreg if explicit truncation is needed
> between the mode of the extraction (word_mode) and the target
> mode. Instead, create a temporary and use convert_move to set
> the target. */
> if (REG_P (target)
> - && TRULY_NOOP_TRUNCATION_MODES_P (GET_MODE (target), ext_mode))
> + && TRULY_NOOP_TRUNCATION_MODES_P (GET_MODE (target), ext_mode)
> + && (temp = gen_lowpart_if_possible (ext_mode, target)))
> {
> - target = gen_lowpart (ext_mode, target);
> + target = temp;
> if (partial_subreg_p (GET_MODE (spec_target), ext_mode))
> spec_target_subreg = target;
> }
> --
> 2.27.0
>
> > target = tem;
> > ...
> >
> > Richard.
> >
> > >
> > > >
> > > > > if (partial_subreg_p (GET_MODE (spec_target), ext_mode))
> > > > > --
> > > > > 2.27.0
> > > > >
> > >
> > >
> > >
> > > --
> > > BR,
> > > Hongtao
>
>
>
> --
> BR,
> Hongtao
