[PATCH v2 00/11] aarch64: Implement TImode comparisons

[Richard Earnshaw (lists)]

On 03/04/2020 13:27, Richard Sandiford wrote:
> "Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com> writes:
>> On 02/04/2020 19:53, Richard Henderson via Gcc-patches wrote:
>>> This is attacking case 3 of PR 94174.
>>>
>>> In v2, I unify the various subtract-with-borrow and add-with-carry
>>> patterns that also output flags with unspecs.  As suggested by
>>> Richard Sandiford during review of v1.  It does seem cleaner.
>>>
>>
>> Really?  I didn't need to use any unspecs for the Arm version of this.
>>
>> R.
> 
> See https://gcc.gnu.org/pipermail/gcc-patches/2020-April/543063.html
> (including quoted context) for how we got here.
> 
> The same problem affects the existing aarch64 patterns like
> *usub<GPI:mode>3_carryinC.  Although that pattern avoids unspecs,
> the compare:CC doesn't seem to be correct.
> 
> Richard
> 

But I don't think you can use ANY_EXTEND in these comparisons.  It
doesn't describe what the instruction does, since the instruction does
not really extend the values first.

I would really expect this patch series to be pretty much a dual of this
series that I posted last year for Arm.

https://gcc.gnu.org/pipermail/gcc-patches/2019-October/532180.html

R.