RE: [PATCH][1/N] Change GET_MODE_INNER to always return a non-void mode

["David Sherwood" <david dot sherwood at arm dot com>]

> 
> On 07/27/2015 04:25 AM, David Sherwood wrote:
> > Hi,
> >
> > Part 1 of this change is a clean-up. I have changed calls to GET_MODE_INNER (m)
> > so that it returns m in cases where there is no inner mode. This simplifies some
> > of the calling code by removing the need to check for VOIDmode and allows
> > calling it unconditionally. I also removed element_precision () as it was only
> > called in one place and thought it neater to call GET_MODE_PRECISION explicitly.
> >
> > Parts 2-4 will include further tidy-ups and optimisations based on [1/N].
> >
> > Good to go?
> >
> > Regards,
> > David Sherwood.
> >
> > 2015-07-17  David Sherwood<david.sherwood@arm.com>
> >
> >      gcc/
> >          * config/arm/arm.c (neon_element_bits, neon_valid_immediate): Call
> >          GET_MODE_INNER unconditionally.
> >          * config/spu/spu.c (arith_immediate_p): Likewise.
> >          * config/i386/i386.c (ix86_build_signbit_mask): Likewise.  New variable.
> >          * expmed.c (synth_mult): Remove check for VOIDmode result from
> >          GET_MODE_INNER.
> >          (expand_mult_const): Likewise.
> >          * fold-const.c (): Replace call to element_precision with call to
> >          GET_MODE_PRECISION.
> >          * genmodes.c (emit_mode_inner_inline): Replace void_mode->name with
> >          m->name.
> >          (emit_mode_inner): Likewise.
> >          * lto-streamer-out.c (lto_write_mode_table): Update GET_MODE_INNER
> >          result check.
> >          * machmode.h (GET_MODE_UNIT_SIZE): Simplify.
> >          (GET_MODE_UNIT_PRECISION): Likewise.
> >          * rtlanal.c (subreg_get_info): Call GET_MODE_INNER unconditionally.
> >          * simplify-rtx.c (simplify_immed_subreg): Likewise.
> >          * stor-layout.c (bitwise_type_for_mode): Update assert.
> >          (element_precision): Remove.
> Somehow my brain kept translating INNER into NARROWER.  Naturally I was
> having considerable trouble seeing how the patch could be correct ;-)
> Looking at insn-modes.h cleared things up quickly.
> 
> In a lot of ways this makes GET_INNER_MODE act more like
> GET_MODE_NUNITS, which is probably good.
> 
> You need to update the comment for GET_MODE_INNER in machmode.h to
> reflect the change in its return value for non-vector modes.
Thanks for the quick response! Before I post a new patch, does this new
comment seem ok?

/* Where MODE represents a vector return the mode of the inner elements,
otherwise just return MODE.  */

Dave.

> 
> With that update, this patch is fine.
> 
> jeff