Integrated: 8255614: Shenandoah: Consolidate/streamline runtime LRBs

[Roman Kennke]

On Fri, 30 Oct 2020 11:06:54 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> Currently, our various LRB entry points are a mess, and quite inefficient too.
> - We have three entry points, one is checking for null, and calls a non-null version, but that checks for null again
> - We don't have to check for null at all: it can be subsumed in the cset-check
> - The LRB resolves forwardee even though has_forwarded_objects() and in_cset() has not been checked
> - The LRB entry is not inlineable
> 
> The proposed change coalesces the 3 entries into one, moves it to shenandoahBarrierSet.inline.hpp and make it inlineable, rearranges the impl to allow cset-check to subsume the NULL-check. As a bonus, it pushes the NULL-check around keep-alive down after the (compile-time) check for weak-ref, so that this path becomes a no-op in the majority of cases.

This pull request has now been integrated.

Changeset: 8600d0d9
Author:    Roman Kennke <rkennke at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/8600d0d9
Stats:     106 lines in 7 files changed: 37 ins; 51 del; 18 mod

8255614: Shenandoah: Consolidate/streamline runtime LRBs

Reviewed-by: zgu

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PR: https://git.openjdk.java.net/jdk/pull/953