Re: [PATCH 3/5] [RISC-V] Generate Zicond instruction for select pattern with condition eq or neq to 0

[Jeff Law <jeffreyalaw@gmail.com>]

On 7/29/23 03:14, Xiao Zeng wrote:

> 
> 1 Thank you for Jeff's code review comments. I have made the modifications
> and submitted the V2-patch[3/5].
Yea.  I'm adjusting my tree based on those updates.  For testing I've 
actually got my compiler generating zicond by default and qemu allowing 
zicond by default.  I can then run the execute.exp tests which validate 
code correctness to a reasonable degree.


> 
> 2 For the calculation method of cost, I hope to submit a separate patch[cost]
> after the V2-patch[3/5] merged into master, which will focus on explaining
> the reasons for calculating cost in the same way as in patch[4/5].
I think the costing problem is going to require its own little 
subproject.  GCC's approach to costing is a bit crazy with multiple APIs 
that behave differently and in some cases do some rather surprising 
things.  It's a long standing design flaw.

The point being that I think we'll probably move forward with the 
functional bits, perhaps initially without the basic functionality 
tests.  That allows folks to start utilizing the core functionality 
while we audit and likely adjust the risc-v cost hook implementation.


> 
> 4. In V2-patch[3/5], Zicond's cost calculation is not involved, therefore, all test
> cases are skipped with "- O0" and "- Os". I will remove the "- Os" constraint from
> the test case in patch[cost].
We may need to avoid for -Og as well.  I've got that change here 
locally, but I wanted to go back and review that as well.

jeff