We set VL/VTYPE these 2 implicit global status denpency register as fixed reg.
Then CSE can do the optimization now.

>> Yea.  I'm wondering about when the right place to introduce these
>>dependencies might be.  I'm still a few months out from worrying about
>>RVV, but it's not too far away.
You don't need to worry about RVV. I can promise you that RVV support in GCC will be solid and
optimal. You can just try. For example, try VSETVL PASS,  this PASS implemented in GCC is much better
than LLVM. I have include so many fancy optimizations there.


juzhe.zhong@rivai.ai
 
From: Jeff Law
Date: 2023-02-02 22:36
To: juzhe.zhong@rivai.ai; rguenther
CC: gcc-patches; kito.cheng; richard.sandiford; apinski
Subject: Re: [PATCH] CPROP: Allow cprop optimization when the function has a single block
 
 
On 2/2/23 05:35, juzhe.zhong@rivai.ai wrote:
> Thank you so much. Kito helped me fix it already.
> RVV instruction patterns can have CSE optimizations now.
What was the issue?
 
jeff