Re: [PATCH] RISC-V: Adjusting the comments of the emit_vlmax_insn/emit_vlmax_insn_lra/emit_nonvlmax_insn functions

[Lehua Ding <lehua.ding@rivai.ai>]

Hi Robin,

> I once had different comments for those but either I never pushed them
> or they got buried in the process of refactoring.  The explanatory
> comment explaining vlmax is also in "nowhere land" below autovec_use_vlmax_p.
> (it says vsetvli instead of vsetvl as well...)  It would be useful
> to move it to above the function comments you touch.

I would like to move this comment to insn_expander::emit_insn body 
before set avl in another patch which add VLS avl_type.

> 
>> +/* Emit RVV insn which vl is the number of units of the vector mode.
>> +   This function can only be used before LRA pass or for VLS_AVL_IMM modes.  */
> 
> Emit an RVV insn with a vector length that equals the number of units of
> the vector mode.  For VLA modes this corresponds to VLMAX.
> 
> Unless the vector length can be encoded in the vsetivl[i] instruction this
> function must only be used as long as we can create pseudo registers.
> This is because it will set a pseudo register to VLMAX using vsetvl and
> use this as definition for the vector length.
> 
> 
> Besides, we could add a const_vlmax_p () || can_create_pseudo_p assert here?
> 
> 
>> +/* Like emit_vlmax_insn but can be only used after LRA pass that can't create
>> +   pseudo register.  */
> 
> Like emit_vlmax_insn but must only be used when we cannot create pseudo
> registers anymore.  This function, however, takes a predefined vector
> length from the value in VL.
> 
>> +/* Emit RVV insn which vl is the VL argument.  */
>> +emit_nonvlmax_insn (unsigned icode, unsigned insn_flags, rtx *ops, rtx vl)
> 
> I think I renamed this to emit_len_insn or something before but Juzhe didn't
> like it ;)
> 
> How about something like:
> Emit an RVV insn with a predefined vector length.  Contrary to emit_vlmax_insn
> the instruction's vector length is not deduced from its mode but taken from
> the value in VL.

Thank you very much, I used all of them. Here the V2 patch:
https://gcc.gnu.org/pipermail/gcc-patches/2023-September/631114.html

-- 
Best,
Lehua (RiVAI)
lehua.ding@rivai.ai