On Wed, 21 Jan 2026 16:47:43 GMT, Aleksey Shipilev <[email protected]> wrote:
>> Shenandoah and G1 are using CardTable for most of its infrastructure, but >> flip the card tables as they go, and maintain the actual card table >> reference in TLS. As such, accessing card table base from assembler and >> compilers runs into risk of accidentally encoding the wrong card table base >> in generated code. >> >> Most of the current code avoids this trouble by carefully implementing their >> GC barriers to avoid touching shared parts where card table base constness >> is assumed. _Except_ for JVMCI, that reads the card table base for G1 >> barrier set, and that is wrong. The JVMCI users would need to rectify this >> downstream. >> >> Shenandoah added a few asserts to catch these errors: >> SHENANDOAHGC_ONLY(assert(!UseShenandoahGC, "Shenandoah byte_map_base is not >> constant.");) >> >> ...but G1 would also benefit from the similar safety mechanism. >> >> This PR strengthens the code to prevent future accidents. >> >> Additional testing: >> - [x] Linux x86_64 server fastdebug, `hotspot_gc` >> - [x] Linux x86_64 server fastdebug, `all` with Serial, Parallel, G1, >> Shenandoah, Z >> - [x] Linux AArch64 server fastdebug, `all` with Serial, Parallel, G1, >> Shenandoah, Z >> - [x] GHA, cross-compilation only > > Aleksey Shipilev has refreshed the contents of this pull request, and > previous commits have been removed. The incremental views will show > differences compared to the previous content of the PR. The pull request > contains one new commit since the last revision: > > Some polishing Thanks! The only GHA failure is due to (the absence of): https://github.com/openjdk/jdk/pull/29254. Looking for a second Reviewer! ------------- PR Comment: https://git.openjdk.org/jdk/pull/28703#issuecomment-3785460384
