Eric Botcazou <botca...@adacore.com> writes:
>> The new variables seem to be unused, so I think slightly stronger
>> DCE could remove the calls even after the patch. Perhaps the containing
>> functions should take an int32x4_t *ptr or something, with the calls
>> assigning to different ptr[] indices.
>
> We run a minimal DCE pass at -O0 in our compiler to eliminate all the garbage
> generated by the gimplifier for variable-sized types (people care about code
> size at -O0 in specific contexts) but it does not touch anything written by
> the user (and debugging is unaffected of course). Given that the builtins
> are
> pure functions and the arguments have no side effects, it eliminates the
> calls, but adding a LHS blocks that because this minimal DCE pass preserves
> anything user-related, in particular assignments to user variables.
>
>> I think it would be better to do that using new calls though,
>> and xfail the existing ones when they no longer work. For example:
>>
>> /* { dg-error "lane -1 out of range 0 - 7" "" {target *-*-*} 0 } */
>> vqdmlal_high_laneq_s16 (int32x4_a, int16x8_b, int16x8_c, -1);
>> /* { dg-error "lane -1 out of range 0 - 7" "" {target *-*-*} 0 } */
>> ptr[0] = vqdmlal_high_laneq_s16 (int32x4_a, int16x8_b, int16x8_c, -1);
>>
>> That way we don't lose the existing tests.
>
> Frankly I'm not quite sure of what we can lose by adding a LHS here, can you
> elaborate a bit? We would need a solution that works out of the box with our
> compiler in the future, i.e. without having to tweak 50 testcases again.
Hi Richard,
Thank for your reply !
As Éric, I'm also wondering why having LHS in the existing tests would
make us loose them. I guess I'm not familiar enough with this part of
the testsuite and I'm missing something.
Thanks,
Marc
