[jdk8u-dev] RFR: 8186787: clang-4.0 SIGSEGV in Unsafe_PutByte [v2]

[Zdenek Zambersky]

On Wed, 26 Feb 2025 13:03:10 GMT, Zdenek Zambersky <zzambers at openjdk.org> wrote:

>> This backport fixes [failures](https://github.com/zzambers/jdk8u-dev/actions/runs/9858657012/job/27221579883) (segfaults) in following tests which appeared after [macos update](https://github.com/openjdk/jdk8u-dev/pull/544):
>> 
>> sun/misc/CopyMemory.java 
>> compiler/unsafe/OpaqueAccesses.java
>> 
>> Backport differs from original changeset, because there were significant changes/refactoring in unsafe.
>> 
>> **Notes:**
>> - [original changeset](https://github.com/openjdk/jdk11u-dev/commit/6dc1d8c06d98e127b022886172e16b90bf357c97) changes pointer returned by `addr` (`MemoryAccess` class), to volatile. Otherwise it is basically just refactoring.
>> - `MemoryAccess` is used by `Unsafe_{Set,Put}*` and `Unsafe_{Set,Put}*Volatile` functions, defined using `DEFINE_GETSETOOP` and `DEFINE_GETSETOOP_VOLATILE` macros
>> - jdk8 does not have `MemoryAccess` class, so equivalent pointers, in functions mentioned higher, are cast to volatile, to achieve same effect
>> 
>> Testing:
>> Tier1: OK (fixes `sun/misc/CopyMemory.java` and `compiler/unsafe/OpaqueAccesses.java` tests on macos, 1 failure on Linux x86 is timeout - seems unrelated, macos failures explained here: https://github.com/openjdk/jdk8u-dev/pull/544#issuecomment-2250636257)
>
> Zdenek Zambersky has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Add comment
>  - Unsafe fix

GHA tests: OK

Failures:
- linux x86 failures (know troublemakers/unstable tests)
  - `gc/concurrentMarkSweep/SystemGCOnForegroundCollector.java` (known, see: [JDK-8303159](https://bugs.openjdk.org/browse/JDK-8303159))
  - `gc/logging/TestGCId.java` - timeout (known, occasionally timeouts on linux x86)
- `jdk/security_infra` - unrelated

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PR Comment: https://git.openjdk.org/jdk8u-dev/pull/553#issuecomment-2685375495