RFR: 8321122: Shenandoah: Remove ShenandoahLoopOptsAfterExpansion flag

[Aleksey Shipilev]

On Mon, 4 Dec 2023 15:52:53 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> > I thought late barrier insertion basically avoids dealing with any optimizer questions, as we insert the barriers close to emit. So if we are to do late barrier insertion, we don't need the bulk of barrier optimization code? Maybe I misunderstand where late barrier insertion fits in C2.
> 
> But the flag you're removing controls optimizations of the barrier code once expanded.

Ah, yes. The late insertion relies on assumption that the barrier is somehow lightweight to not require post-insertion optimization. That might not be true for Shenandoah (and G1) barriers.

Anyway, would you like to keep the flag in, or should we integrate this PR?

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PR Comment: https://git.openjdk.org/jdk/pull/16908#issuecomment-1841419106