Christophe Lyon <christophe.l...@arm.com> writes:
> On 5/10/23 16:52, Kyrylo Tkachov wrote:
>>
>>
>>> -----Original Message-----
>>> From: Christophe Lyon <christophe.l...@arm.com>
>>> Sent: Wednesday, May 10, 2023 2:31 PM
>>> To: gcc-patches@gcc.gnu.org; Kyrylo Tkachov <kyrylo.tkac...@arm.com>;
>>> Richard Earnshaw <richard.earns...@arm.com>; Richard Sandiford
>>> <richard.sandif...@arm.com>
>>> Cc: Christophe Lyon <christophe.l...@arm.com>
>>> Subject: [PATCH 15/20] arm: [MVE intrinsics] add unary_acc shape
>>>
>>> This patch adds the unary_acc shape description.
>>>
>>> 2022-10-25 Christophe Lyon <christophe.l...@arm.com>
>>>
>>> gcc/
>>> * config/arm/arm-mve-builtins-shapes.cc (unary_acc): New.
>>> * config/arm/arm-mve-builtins-shapes.h (unary_acc): New.
>>> ---
>>> gcc/config/arm/arm-mve-builtins-shapes.cc | 28 +++++++++++++++++++++++
>>> gcc/config/arm/arm-mve-builtins-shapes.h | 1 +
>>> 2 files changed, 29 insertions(+)
>>>
>>> diff --git a/gcc/config/arm/arm-mve-builtins-shapes.cc b/gcc/config/arm/arm-
>>> mve-builtins-shapes.cc
>>> index bff1c3e843b..e77a0cc20ac 100644
>>> --- a/gcc/config/arm/arm-mve-builtins-shapes.cc
>>> +++ b/gcc/config/arm/arm-mve-builtins-shapes.cc
>>> @@ -1066,6 +1066,34 @@ struct unary_def : public overloaded_base<0>
>>> };
>>> SHAPE (unary)
>>>
>>> +/* <S0:twice>_t vfoo[_<t0>](<T0>_t)
>>> +
>>> + i.e. a version of "unary" in which the source elements are half the
>>> + size of the destination scalar, but have the same type class.
>>> +
>>> + Example: vaddlvq.
>>> + int64_t [__arm_]vaddlvq[_s32](int32x4_t a)
>>> + int64_t [__arm_]vaddlvq_p[_s32](int32x4_t a, mve_pred16_t p) */
>>> +struct unary_acc_def : public overloaded_base<0>
>>> +{
>>> + void
>>> + build (function_builder &b, const function_group_info &group,
>>> + bool preserve_user_namespace) const override
>>> + {
>>> + b.add_overloaded_functions (group, MODE_none,
>>> preserve_user_namespace);
>>> + build_all (b, "sw0,v0", group, MODE_none, preserve_user_namespace);
>>> + }
>>> +
>>> + tree
>>> + resolve (function_resolver &r) const override
>>> + {
>>> + /* FIXME: check that the return value is actually
>>> + twice as wide as arg 0. */
>>
>> Any reason why we can't add that check now?
>> I'd rather not add new FIXMEs here...
>
> I understand :-)
>
> That's because the resolver only knows about the arguments, not the
> return value:
> /* The arguments to the overloaded function. */
> vec<tree, va_gc> &m_arglist;
>
> I kept this like what already exists for AArch64/SVE, but we'll need to
> extend it to handle return values too, so that we can support all
> overloaded forms of vuninitialized
> (see https://gcc.gnu.org/pipermail/gcc-patches/2023-April/616003.html)
>
> I meant this extension to be a follow-up work when most intrinsics have
> been converted and the few remaining ones (eg. vuninitialized) needs an
> improved framework. And that would enable to fix the FIXME.
We can't resolve based on the return type though. It has to be
arguments only. E.g.:
decltype(foo(a, b))
has to be well-defined, even though decltype (by design) provides no
context about "what the caller wants".
Thanks,
Richard
