RFR(L): JEP165: Compiler Control

Christian Thalinger christian.thalinger at oracle.com
Tue Sep 22 21:22:47 UTC 2015

Here are a couple of comments I had after looking over this briefly:


+   DirectiveSet* dirset() { return _directive_set; }

Can you change the name of this method?  I’d go with directive_set() (or directives(); see below).


Could DirectiveSet maybe just be called Directives?

  89   bool inline_commanded(ciMethod* inlinee);
  90   bool dont_inline_commanded(ciMethod* inlinee);

I’d call these should_inline and should_not_inline.

  92   DirectiveSet* late_cc_init(methodHandle method);

What does late_cc_init mean?  Please use a more descriptive name.


Rename these files to directivesParser.*


Will this JSON code be used by other code later?

> On Sep 22, 2015, at 7:21 AM, Nils Eliasson <nils.eliasson at oracle.com> wrote:
> Hi,
> This is the initial RFR for JEP165: Compiler Control. This feature enables runtime manageable, method dependent compiler flags. (Immutable for the duration of a compilation.)
> The change includes:
> - A parser for the directives format (json like) including vmtests (json.cpp/hpp)
> - A component for construction of compiler directives (directivesParser.cpp/hpp)
> - The directives including the option definitions, default values and compilecommand relations (compilerDirectives.cpp/hpp)
> - Diagnostic commands for working with the directives - installing, removing, printing
> - Lots of small changes wherever we access flags or legacy compilecommands in the compiler
> Notes:
> The feature is documented in the JEP (https://bugs.openjdk.java.net/browse/JDK-8046155).
> Currently only a small amount of compiler flags are included in the change. The flags are a representative selection of different types targeting both compilers. All of them existed as CompilerOracle option commands. Two commands was not included in the directives due to time constraints - CompilerThresholdScaling and UseRTMLocks. Both are accessed from runtime (outside any compiler) and requires some special handling. (Solved but not implemented.)
> Full backwards compatibility with CompileCommands is implemented but can be turned off with flag -XX:CompileCommandCompatibilty. Also meta handling the compatibility flag by supporting it in the directives (test feature).
> The change contain some rough edges that will polished over the coming days.
> JEP: https://bugs.openjdk.java.net/browse/JDK-8046155
> Hotspot webrev: http://cr.openjdk.java.net/~neliasso/8046155/webrev.01/
> JDK webrev: http://cr.openjdk.java.net/~neliasso/8046155/webrev_jdk.01/
> Please review!
> Best regards,
> Nils Eliasson

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