RFR: Purge support for ShenandoahConcurrentEvacCodeRoots and ShenandoahBarriersForConst

[Roman Kennke]

Am 02.08.2018 um 18:15 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/purge-concevac-coderoots/webrev.01/
> 
> This is the leftover from our not entirely successful experiment to get code roots pre-evac-ed
> concurrently. This requires emitting barriers after constants in the generated code when enabled,
> which complicates compiler logic. Since then, we have improved our pre-evac times by tracking which
> regions contain which code roots (ShenandoahCodeRootsStyle=2), which makes this code irrelevant.
> 
> Traversal enables ShenandoahBarriersForConst to avoid pre-evac on some paths, Roman is fixing it
> now. It does not seem to affect normal operation, unless class unloading is enabled for traversal,
> which it is not. This must be why tier3 passes.
> 
> Testing: tier3_gc_shenandoah
> 

Very good! Less code to drag around ;-)

Thanks!

Roman