Integrated: 8256883: C2: Add a RegMask iterator

Tue Nov 24 14:39:03 UTC 2020

On Mon, 23 Nov 2020 18:01:01 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> By implementing a simple RegMaskIterator we can speed this up and possibly make the code a bit clearer by doing so.
> 
> As a data point, this reduce the `C2Compiler::initialize` overhead from 8.82M instructions to 8.58M instructions, from the improvement in `PhaseChaitin::post_allocate_copy_removal` (~16k insns/compilation). The gain varies with type of compilation, so on the naive tests in `SimpleRepeatCompilation` it's in the noise (~2k insns/compilation on `trivialMath, for example).

This pull request has now been integrated.

Changeset: fa3cfcd0
Author:    Claes Redestad <redestad at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/fa3cfcd0
Stats:     93 lines in 6 files changed: 48 ins; 15 del; 30 mod

8256883: C2: Add a RegMask iterator

Reviewed-by: kvn, pliden, eosterlund

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PR: https://git.openjdk.java.net/jdk/pull/1397