Re: [PATCH v7] RISC-V: Support CALL for RVV floating-point dynamic rounding

[Jeff Law <jeffreyalaw@gmail.com>]

On 7/26/23 16:21, 钟居哲 wrote:
> Hi, Jeff.
> 
> insert_insn_end_basic_block is to handle this following case:
> 
> bb 1:
> ...
> CALL.---->BB_END of bb
> bb 2:
> vfadd rne
> 
> You can see there is no instructions after CALL.
> 
> So you we use insert_insn_end_basic_block insert a "frrm" at the end of 
> the bb 1.
> 
> I know typically it's better to insert a edge between bb 1 and bb 2, 
> then put "frrm" in that edgen.
> However, it causes ICE.
We'd need to know the reason for the ICE.

> 
> If we really need to follow this approach, it seems that we need to 
> modify the "mode_sw" PASS?
> Currently, we are avoiding changing the codes of PASS.
Generally wise, but sometimes we do need to change generic bits.  Let's 
dive a bit into this.

We have more freedom here to loosen the profitability constraints since 
its a target specific pass, but let's at least understand the what's 
going on with the ICE, then make some decisions about the best way forward.

jeff