Integrated: 8358334: C2/Shenandoah: incorrect execution with Unsafe

[Roland Westrelin]

On Tue, 10 Jun 2025 14:13:21 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> When a barrier is expanded, some control is picked as a location for
> the barrier. The control input of data nodes that depend on that
> control are updated so the nodes are after the expanded barrier unless
> the barrier itself depends on some of those nodes.
> 
> In this particular failure, a raw memoy `Store` is the input memory to
> the barrier. That `Store` has an anti-dependent `Load`. All 3 nodes
> (barrier, `Load` and `Store`) are at the same control. The `Store` is
> an input to the barrier so it stays before the barrier. The `Load`'s
> control is updated to be after the barrier which breaks the
> anti-dependency. The bug is that the logic that sorts nodes that need
> to be before the barrier and those that can be after ignores
> anti-dependencies. The fix simply extends that logic to take them into
> account.

This pull request has now been integrated.

Changeset: 1fcede05
Author:    Roland Westrelin <roland at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/1fcede053cca360c96606c1034b2a365a4fada82
Stats:     153 lines in 3 files changed: 117 ins; 26 del; 10 mod

8358334: C2/Shenandoah: incorrect execution with Unsafe

Reviewed-by: wkemper, shade

-------------

PR: https://git.openjdk.org/jdk/pull/25729