On Thu, 5 Sep 2024 17:47:16 GMT, Per Minborg <pminb...@openjdk.org> wrote:
>> This PR proposes to improve the performance of `MemorySegment::mismatch` by
>> using Java code rather than transitioning to native code.
>
> Per Minborg has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Fix errors in a benchmark
src/java.base/share/classes/jdk/internal/foreign/SegmentBulkOperations.java
line 76:
> 74: final int limit = (int) (dst.length & (NATIVE_THRESHOLD_FILL
> - 8));
> 75: for (; offset < limit; offset += 8) {
> 76: SCOPED_MEMORY_ACCESS.putLong(dst.sessionImpl(),
> dst.unsafeGetBase(), dst.unsafeGetOffset() + offset, longValue);
Now that I look again at this - I think all these calls should use
`putXYZUnaligned`. Otherwise alignment can introduce issues on some platforms.
That will call an `Unsafe` intrinsics that will do the best possible job at
serving a potentially unaligned request. This is, btw, what we use when we do
e.g. `segment.get(JAVA_LONG, offset)`. Since you are using a lower-level API
here, you need to make sure you use the correct memory access primitive.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20848#discussion_r1745959346
