On Mon, 21 Oct 2024 01:29:16 GMT, Shaojin Wen <s...@openjdk.org> wrote:
>> Shaojin Wen 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 26 additional >> commits since the last revision: >> >> - Merge remote-tracking branch 'origin/optim_str_builder_append_202406' >> into optim_str_builder_append_202406 >> - fix build error >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - Merge remote-tracking branch 'origin/optim_str_builder_append_202406' >> into optim_str_builder_append_202406 >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - revert test >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - Merge remote-tracking branch 'upstream/master' into >> optim_str_builder_append_202406 >> - ... and 16 more: https://git.openjdk.org/jdk/compare/25212971...457735c9 > > There is no array out-of-bounds check when using Unsafe. In the appendNull > method, there is already a call to ensureCapacityInternal. It is also safe to > use Unsafe in this scenario. @wenshao @cl4es I've investigated a little with the benchmark. RangeCheck smearing could be the issue here.  It turns out that RangeChecks are smeared (a kind of elimination in straight-line code) in the same phase as the MergeStores happens (`post_loop_opts_phase`). So it seems to depend on the order of processing in the worklist, if we first remove the RC or try to merge the stores. If a RC is somewhere still stuck between stores, then merging does not quite work as hoped. Of course if you do it all with `Unsafe`, then those RC are not there any more. Maybe I can somehow delay the MergeStores a little more. But I have nice solution in mind - only hacks so far 😅 . ------------- PR Comment: https://git.openjdk.org/jdk/pull/19626#issuecomment-2425810572
