RFR: 8332670: C1 clone intrinsic needs memory barriers

[Martin Doerr]

On Tue, 4 Jun 2024 08:10:59 GMT, Galder Zamarreño <galder at openjdk.org> wrote:

> Adds a storestore barrier after copying the contents in the primitive array intrinsic (credit @shipilev). The barrier is a no-op in platforms where not needed so no need for an ifdef.
> 
> The barrier after new array creation is only added if zeroing the array on aarch64 (credit @dean-long). Since the primitive array clone intrinsic does not zero the array, that means there's a single barrier added for this use case.
> 
> There's no barrier added on x86 c1 macro assembler for nothing to do there. 
> 
> I've run the following tests:
> * tier 1 on darwin/aarch64
> * tier 1 on linux/x86_64
> * `hotspot_compiler` tests on darwin/aarch64
> * `copy.clone.arrays` jcstress tests on darwin/aarch64.
> 
> I tried but was unable to create a standalone test for the jdk source tree that would fail.
> 
> FYI @bulasevich @TheRealMDoerr @RealFYang @RealLucy similar platform specific c1 macro assembler changes might be required for other platforms.

PPC64 adds storestore barriers in LIR (not in assembler as aarch64): https://github.com/openjdk/jdk/blob/8d3de45f4dfd60dc4e2f210cb0c085fcf6efb8e2/src/hotspot/cpu/ppc/c1_LIRGenerator_ppc.cpp#L928
I think this fits nicely to your change.

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

PR Comment: https://git.openjdk.org/jdk/pull/19538#issuecomment-2147920726