Hello, This is (yet another) cleanup to remove redundant memory barriers after the new ValuePayload abstraction API in the runtime. The ValuePayload API's (including FlatValuePayload::read) does the necessary calls to order stores of the copy before the oop is published (OrderAccess::storestore), making the platform-specific memory barriers redundant.
I don't have hardware access to RISCV or PPC, but looking at the runtime implementations of OrderAccess::storestore, they achieve the same thing as the platform-specific memory barriers that I suggest we remove in this PR. GHA will show that this compiles at least. `membar(Assembler::StoreStore | Assembler::LoadLoad);` and `OrderAccess::storestore()` both boil down to `lwsync`. The C1 call to `load_flat_array` already omits the memory barrier, so we don't need to remove it here. Testing: * Oracle's tier1-3 linux-aarch64 * GHA --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - 8386889: [lworld] Redundant StoreStore membar after FlatValuePayload::read Changes: https://git.openjdk.org/valhalla/pull/2581/files Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2581&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8386889 Stats: 12 lines in 6 files changed: 0 ins; 12 del; 0 mod Patch: https://git.openjdk.org/valhalla/pull/2581.diff Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2581/head:pull/2581 PR: https://git.openjdk.org/valhalla/pull/2581
