RFR: 8341697: C2: Register allocation inefficiency in tight loop [v7]

[Daniel Lundén]

On Wed, 28 May 2025 15:22:29 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> src/hotspot/share/opto/reg_split.cpp line 522:
>> 
>>> 520:     Block* b = cfg.get_block(bidx);
>>> 521:     if (!loop->in_loop_nest(b)) {
>>> 522:       continue;
>> 
>> Is there not a more efficient way to iterate through all the loops in the loop nest?
>
> We are iterating through all the blocks in the loop nest. There is probably a more straight-forward way.

Yes, thanks, blocks is what I meant to write. OK, I can investigate if there is a more straightforward way.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21472#discussion_r2112208526