Re: Re: [PATCH 0/5] Recognize Zicond extension

["Xiao Zeng" <zengxiao@eswincomputing.com>]

On Thu, Jul 27, 2023 at 10:43:00 PM  Jeff Law <jeffreyalaw@gmail.com> wrote:
>
>
>
>On 7/27/23 02:43, Xiao Zeng wrote:
>
>>
>> 2. According to your opinions, I have modified the code, but out of caution
>> for upstream, I conducted a complete regression tests on patch V2, which took
>> some time. I was unable to reply to emails and upload patch V2 in a timely manner.
>Sorry to have wasted your time 

It's okay
I am very willing to accept opinions from the gcc community.

>-- zicond/xventanacondops has lingered
>for quite a while and I had a bit of free time yesterday.  I felt it was
>most useful to try and move this stuff forward.
>
>
>
>>
>> 3 After you and other maintainers made minor modifications to my patch[1/5]
>> and patch[2/5], it has been merged into the master, so I will no longer upload patch V2.
>Agreed.
>
>>
>> 4 patch[1/5] and patch[2/5], which have been merged into the master, have only
>> completed basic support for Zicond, and further optimization work needs to be
>> completed. These further optimization reactions are reflected in my patch[3/5]
>> patch[4/5] and patch[5/5].
>Agreed.
>
>>
>> 5 As you mentioned in your previous email https://gcc.gnu.org/pipermail/gcc-patches/2023-July/625427.html
>> "eswincomputing and ventana can both reduce our divergence from the trunk
>> and work together on the rest of the bits...". I will reorganize patch[3/5] patch[4/5]
>> and patch[5/5], provide more detailed explanations, and submit them as an alternative
>> solution for further optimization of Zicond.
>>
>> Does that work for you?
>I'm going to look at 3/5 today pretty closely.  Exposing zicond to
>mov<node>cc is something we had implemented inside Ventana and I want to
>compare/contrast your work with ours. 

What a coincidence!

>
>What I like about yours is it keeps all the logic in riscv.cc rather
>than scattering it across riscv.cc and riscv.md.  

Yes, when I use enough test cases, I cannot find a concise way to optimize
all test cases. When I enumerated all possible cases in the mov<mode>cc
function of the RISC-V backend, I found a method that satisfied me, which
is the method in patch [3/5].

>What I like about the
>internal Ventana bits is its ability to support arbitrary comparisons by
>utilizing sCC if the original is not an eq/ne comparison.
> 

If it's just for the Zicond instruction set, is it necessary to make judgments
outside of eq/ne? After all, it does not support comparison actions other
than eq/ne. Of course, it is also possible to use a special technique to use
Zicond in non eq/ne comparisons.

>Ideally we'll be able to get the best of both. 

Of course, it is best to unify all situations in one framework.

>
>Jeff

Now that the code on the master has preliminary support for
Zicond, I will still submit the optimization patches for Zicond to
the community for the convenience of finding the ideal method.

Thanks
Xiao Zeng