Re: [PATCH] RISC-V: Refactor and clean emit_{vlmax,nonvlmax}_xxx functions

[Robin Dapp <rdapp.gcc@gmail.com>]

Hi Lehua,

thanks, this definitely goes into the direction of what I had in mind and
simplifies a lot of the reduntant emit_... so it's good to have it.

I was too slow for a detailed response :)  So just some high-level comments.

One thing I noticed is the overloading of "MASK_OP",  we use it as
"operation on masks" i.e. an insn as well as "mask policy".  IMHO we could
get rid of UNARY_MASK_OP and BINARY_MASK_OP and just decide whether to
add a mask policy depending on if all operands are masks (the same way we
did before).

Related, and seeing that the MASK in UNARY_MASK_OP is somewhat redundant,
I feel we still mix concerns a bit.  For example it is not obvious, from
the name at least, why a WIDEN_TERNARY_OP does not have a merge operand
and the decision making seems very "enum centered" now :D

In general we use the NULLARY, UNARY, BINARY, TERNARY prefixes just
to determine the number of sources which doesn't seem really necessary
because a user of e.g. NEG will already know that there only is one
source - he already specified it and currently needs to, redundantly,
say UNARY again.
 
If we split off the destination and sources from mask, merge and the rest
we could ditch them altogether.

What about
 emit_(non)vlmax_insn (icode, *operands (just dest and sources),
		       mask, merge, tail/mask policy, frm)

with mask defaulting to NULL and merge defaulting to VUNDEF?  So ideally,
and in the easy case, the call would just degenerate to
 emit_..._insn (icode, operands).
 
I realize this will cause some complications on the "other side" but with
the enum in place it should still be doable?

No need to address this right away though, just sharing some ideas again.

Regards
 Robin