Re: Add support for adjusting the number of units in a mode

[Jeff Law <law at redhat dot com>]

On 11/09/2017 04:08 AM, Richard Sandiford wrote:
> Jeff Law <law@redhat.com> writes:
>> On 10/25/2017 09:57 AM, Richard Sandiford wrote:
>>> We already allow the target to change the size and alignment of a mode.
>>> This patch does the same thing for the number of units, which is needed
>>> to give command-line control of the SVE vector length.
>>>
>>> Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64le-linux-gnu,
>>> on top of the poly_int series.  I think I can approve this under the
>>> gen* maintainership, so if there are no comments in the menatime,
>>> I'll apply it if the prerequisites are approved.
>>>
>>> Thanks,
>>> Richard
>>>
>>>
>>> 2017-10-25  Richard Sandiford  <richard.sandiford@linaro.org>
>>> 	    Alan Hayward  <alan.hayward@arm.com>
>>> 	    David Sherwood  <david.sherwood@arm.com>
>>>
>>> gcc/
>>> 	* machmode.h (mode_precision): Prefix with CONST_MODE_PRECISION.
>>> 	(mode_nunits): Likewise CONST_MODE_NUNITS.
>>> 	* machmode.def (ADJUST_NUNITS): Document.
>>> 	* genmodes.c (mode_data::need_nunits_adj): New field.
>>> 	(blank_mode): Update accordingly.
>>> 	(adj_nunits): New variable.
>>> 	(print_maybe_const_decl): Replace CATEGORY with a NEEDS_ADJ
>>> 	parameter.
>>> 	(emit_mode_size_inline): Set need_bytesize_adj for all modes
>>> 	listed in adj_nunits.
>>> 	(emit_mode_nunits_inline): Set need_nunits_adj for all modes
>>> 	listed in adj_nunits.  Don't emit case statements for such modes.
>>> 	(emit_insn_modes_h): Emit definitions of CONST_MODE_NUNITS
>>> 	and CONST_MODE_PRECISION.  Make CONST_MODE_SIZE expand to
>>> 	nothing if adj_nunits is nonnull.
>>> 	(emit_mode_precision, emit_mode_nunits): Use print_maybe_const_decl.
>>> 	(emit_mode_unit_size, emit_mode_base_align, emit_mode_ibit)
>>> 	(emit_mode_fbit): Update use of print_maybe_const_decl.
>>> 	(emit_move_size): Likewise.  Treat the array as non-const
>>> 	if adj_nunits.
>>> 	(emit_mode_adjustments): Handle adj_nunits.
>> Were all the prereqs here approved?  Or does this depend on the poly_int
>> stuff?
> 
> Yeah, it depends on the poly_int stuff.  Not in a major way though --
> I could reorder it if necessary.
Your call.  I figure it's going to be at least a week working my way
through the rest of poly_int.  I keep hoping to see groups of patches
within that kit that I can trivially look at and say, yea, of course
this is good.  But it hasn't really happened yet.

jeff