RFR: 8325937: runtime/handshake/HandshakeDirectTest.java causes "monitor end should be strictly below the frame pointer" assertion failure on AArch64

[David Holmes]

On Tue, 1 Oct 2024 18:38:33 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Add missing StoreLoad fences in handshaking code to match safepoint code.  Thanks to @pchilano for finding this bug.
> 
> Tested with tier1-4 and tier8 which has Kitchensink in it.

If accesses can move out of a critical section then it completely breaks locking! Locking is supposed to provide roach-motel semantics: you can move in but never out.

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PR Comment: https://git.openjdk.org/jdk/pull/21295#issuecomment-2388018417