RFR: 8257221: C2: RegMask::is_bound_set split set handling broken since JDK-8221404 [v2]

Sat Nov 28 23:23:57 UTC 2020

On Sat, 28 Nov 2020 00:32:08 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> This patch adds more tests for RegMask::is_bound* operations, and fixes a bug I introduced in JDK-8221404 where I mixed up the formula for how much we need to shift the "bit" when checking a split set.
>> 
>> This also optimizes RegMask::is_bound (~2x) by removing use of Size() in is_bound1 and streamlining the three component methods (is_bound1, is_bound_pair, is_bound_set) so that they all do a cheap check that the remaining words are all zero after a matching bit, pair or set has been found.
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Split out the optimization

Looks good.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1486