Re: [PATCH V3] RISC-V: Adjust scalar_to_vec cost

[juzhe.zhong]

VLA is a known issue for a long time.

GCC doesn't have too much cse optimization for

VLA vectors. It should be a big work to investigate what's going on.

I think most cse optimization for precomputed result are vls loop. So I think as long as we can do a good job on cost model which pick appropriate vls loop. It's not big issue and not high priority for me.

---- Replied Message ----

From	Robin Dapp<rdapp....@gmail.com>
Date	01/12/2024 18:10
To	Juzhe-Zhong<juzhe.zh...@rivai.ai>, gcc-patches@gcc.gnu.org<gcc-patches@gcc.gnu.org>
Cc	rdapp....@gmail.com<rdapp....@gmail.com>, kito.ch...@gmail.com<kito.ch...@gmail.com>, kito.ch...@sifive.com<kito.ch...@sifive.com>, jeffreya...@gmail.com<jeffreya...@gmail.com>
Subject	Re: [PATCH V3] RISC-V: Adjust scalar_to_vec cost

> Tested on both RV32/RV64 no regression, Ok for trunk ?

Yes, thanks!

Btw out of curiosity, did you see why we actually fail to
optimize away the VLA loop?  We should open a bug for that
I suppose.

Regards
Robin