> Compiler Control (https://openjdk.org/jeps/165) provides method-context > dependent control of the JVM compilers (C1 and C2). The active directive > stack is built from the directive files passed with the > `-XX:CompilerDirectivesFile` diagnostic command-line option and the > Compiler.add_directives diagnostic command. It is also possible to clear all > directives or remove the top from the stack. > > A matching directive will be applied at method compilation time when such > compilation is started. If directives are added or changed, but compilation > does not start, then the state of compiled methods doesn't correspond to the > rules. This is not an error, and it happens in long running applications when > directives are added or removed after compilation of methods that could be > matched. For example, the user decides that C2 compilation needs to be > disabled for some method due to a compiler bug, issues such a directive but > this does not affect the application behavior. In such case, the target > application needs to be restarted, and such an operation can have high costs > and risks. Another goal is testing/debugging compilers. > > It would be convenient to optionally reconcile at least existing matching > nmethods to the current stack of compiler directives (so bypass inlined > methods). > > Natural way to eliminate the discrepancy between the result of compilation > and the broken rule is to discard the compilation result, i.e. > deoptimization. Prior to that we can try to re-compile the method letting > compile broker to perform it taking new directives stack into account. > Re-compilation helps to prevent hot methods from execution in the interpreter. > > A new flag `-r` has beed introduced for some directives related to compile > commands: `Compiler.add_directives`, `Compiler.remove_directives`, > `Compiler.clear_directives`. The default behavior has not changed (no flag). > If the new flag is present, the command scans already compiled methods and > puts methods that have any active non-default matching compiler directives to > re-compilation if possible, otherwise marks them for deoptimization. There is > currently no distinction which directives are found. In particular, this > means that if there are rules for inlining into some method, it will be > refreshed. On the other hand, if there are rules for a method and it was > inlined, top-level methods won't be refreshed, but this can be achieved by > having rules for them. > > In addition, a new diagnostic command `Compiler.replace_directives`, has been > added for ...
Dmitry Chuyko has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 25 commits: - Merge branch 'openjdk:master' into compiler-directives-force-update - Merge branch 'openjdk:master' into compiler-directives-force-update - jcheck - Unnecessary import - force_update->refresh - Merge branch 'openjdk:master' into compiler-directives-force-update - Use only top directive for add/remove; better mutex rank definition; texts - Merge branch 'openjdk:master' into compiler-directives-force-update - Merge branch 'openjdk:master' into compiler-directives-force-update - Safe handling of non-java methods - ... and 15 more: https://git.openjdk.org/jdk/compare/750da001...e451f509 ------------- Changes: https://git.openjdk.org/jdk/pull/14111/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14111&range=06 Stats: 372 lines in 15 files changed: 339 ins; 3 del; 30 mod Patch: https://git.openjdk.org/jdk/pull/14111.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/14111/head:pull/14111 PR: https://git.openjdk.org/jdk/pull/14111
