Re: [PATCH] testsuite: Update some vect cases for partial vectors

[Richard Sandiford <richard.sandiford@arm.com>]

"Kewen.Lin" <linkw@linux.ibm.com> writes:
>>> +# Return true if loops using partial vectors are supported.
>>> +
>>> +proc check_effective_target_vect_partial_vectors { } {
>>> +    return [expr { [check_effective_target_vect_partial_vectors_usage_1]
>>> +		   || [check_effective_target_vect_partial_vectors_usage_2] }]
>>> +}
>>> +
>>> +# Return true if loops using partial vectors are supported and the default
>>> +# value of --param=vect-partial-vector-usage is 1.
>>> +
>>> +proc check_effective_target_vect_partial_vectors_usage_1 { } {
>>> +    return 0
>>> +}
>>> +
>>> +# Return true if loops using partial vectors are supported and the default
>>> +# value of --param=vect-partial-vector-usage is 2.
>>> +
>>> +proc check_effective_target_vect_partial_vectors_usage_2 { } {
>>> +    return [expr { [check_effective_target_vect_fully_masked] }]
>>> +}
>>> +
>> 
>> Could we auto-detect this?  What we really care about isn't the default,
>> but what's currently being tested.
>
> Yeah, the comments were confusing, its intent is to check which targets
> support partial vectors and which usage to be used.
>
> How about to update them like:
>
> "Return true if loops using partial vectors are supported and usage kind is
> 1/2".

I wasn't really commenting on the comment so much as the intent.
It should be possible to run the testsuite with:

  --target_board unix/--param=vect-partial-vector-usage=1

and get the right results.

>> E.g. maybe use check_compile to run gcc with “-Q --help=params” and an
>> arbitrary output type (probably assembly).  Then use “regexp” on the
>> lines to parse the --param=vect-partial-vector-usage value.  At that
>> point it would be worth caching the result.
>
> Now the default value of this parameter is 2, even for those targets which
> don't have the supports with partial vectors.  Since we will get the value
> 2 on those unsupported targets, it looks like we have to set it manually?

I think that just means we want:

vect_len_load_store
  the len_load_store equivalent of vect_fully_masked, i.e. whether
  the target supports len load/store (regardless of whether the
  --param enables it)

vect_partial_vectors
  (vect_fully_masked || vect_len_load_store) && param != 0

vect_partial_vectors_usage_1
  (vect_fully_masked || vect_len_load_store) && param == 1

vect_partial_vectors_usage_2
  (vect_fully_masked || vect_len_load_store) && param == 2

Thanks,
Richard