Date: Tue, 05 Oct 2021 19:44:19 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258954 Bug ID: 258954 Summary: java/openjdk11 java/openjdk12 java/openjdk13: crashes when built with clang 13 Product: Ports & Packages Version: Latest Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: Individual Port(s) Assignee: java@FreeBSD.org Reporter: dim@FreeBSD.org Flags: maintainer-feedback?(java@FreeBSD.org) Assignee: java@FreeBSD.org During an exp-run for llvm 13 (see bug 258209), it turned out that java/openjdk11 through openjdk13 fail to build with clang 13: === Output from failing command(s) repeated here === * For target jdk__packages_attribute.done: # # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x0000000802c8a991, pid=92123, tid=618713 # # JRE version: (11.0.12+7) (build ) # Java VM: OpenJDK 64-Bit Server VM (11.0.12+7-1, mixed mode, tiered, compressed oops, serial gc, bsd-amd64) # Problematic frame: # V [libjvm.so+0xe8a991] JVM_RaiseSignal+0x3bfbf1 # # Core dump will be written. Default location: /wrkdirs/usr/ports/java/openjdk11/work/jdk11u-jdk-11.0.12-7-1/make/java.core # # An error report file with more information is saved as: # /wrkdirs/usr/ports/java/openjdk11/work/jdk11u-jdk-11.0.12-7-1/make/hs_err_pid92123.log These crashes are all caused by the markOop/markOopDesc classes, which are used to keep track of objects, and which are 'marked' using the low few bits. (See https://github.com/openjdk/jdk13u/blob/master/src/hotspot/share/oops/markOop.hpp ). After some laborious bisecting, I found out that these crashes start occuring after the upstream commit https://github.com /llvm/llvm-project/commit/16d03818412 (Return "[CGCall] Annotate this argument with alignment"). What happens afterwards, is that clang considers the "this" pointer to always be aligned to the alignment of the actual object, and then masking or adding a few low bits is not working as expected. The reason openjdk14 and higher work fine with clang 13, and don't crash similarly, is that the OpenJDK people completely redid the markOop/markOopDesc classes in https://github.com/openjdk/jdk/commit/ae5615c6142a4dc0d9033462f4880d7b3c127e26 ("8229258: Rework markOop and markOopDesc into a simpler mark word value carrier"). E.g, the markOopDesc class was renamed to markWord, and *stores* a pointer-like value instead of *being* a pointer-like value. This is a much safer way of handling things. However, this upstream commit is *very* large, as are a few of its follow-ups, which is probably the reason why it has not been backported to JDKs <= 13. I tried manually backporting it, but got lost in many nasty patch conflicts and problems. I would like to solicit some opinions from our OpenJDK maintainers, on how to move forward with this issue. I see a few ways: * Get someone well-versed in OpenJDK internals to backport '8229258: Rework markOop and markOopDesc' (this is a *lot* of tricky stuff, and has to be done for at least 11, 12 and 13; but maybe earlier JDKs too). * Find some alternative way of simplifying the approach in '8229258: Rework markOop and markOopDesc', and backport that * Revert the upstream LLVM commit; I don't really like this because we would have to carry that patch forever (as LLVM upstream won't accept it obviously) * Adjust the port Makefiles for openjdk11 though openjdk13 to use the clang12 port * ... something else? -- You are receiving this mail because: You are the assignee for the bug.