On Wed, 3 Apr 2024 15:15:24 GMT, Scott Gibbons <sgibb...@openjdk.org> wrote:
>> This code makes an intrinsic stub for `Unsafe::setMemory` for x86_64. See >> [this PR](https://github.com/openjdk/jdk/pull/16760) for discussion around >> this change. >> >> Overall, making this an intrinsic improves overall performance of >> `Unsafe::setMemory` by up to 4x for all buffer sizes. >> >> Tested with tier-1 (and full CI). I've added a table of the before and >> after numbers for the JMH I ran (`MemorySegmentZeroUnsafe`). >> >> [setMemoryBM.txt](https://github.com/openjdk/jdk/files/14808974/setMemoryBM.txt) > > Scott Gibbons has updated the pull request incrementally with one additional > commit since the last revision: > > Fix Windows I think the right approach is to turn it into a loop in the IR, which I think is what Doug was implying. That way C2 can do all its usual optimizations, like unrolling, vectorization, and redundant store elimination (if it is an on-heap primitive array that was just allocated, then there is no need to zero the parts that are being "set"). ------------- Changes requested by dlong (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/18555#pullrequestreview-1981533209
