Overview

Lots of files have changed. Please read this document first before heading over to the webrev
Preliminary webrev: http://cr.openjdk.java.net/~iklam/jdk15/vm_flags_overhaul.008/

Goals

Improve the implementation of JVM command-line flags (such as -XX:+UseCompressedOops)
Break up monolithic globals.hpp
- No need to include all flags for GC, C1, C2, JVMCI, .....
- Before:
  - #include "runtime/globals.hpp" + globals_shared.hpp = declare all possible flags
- After:
  - If you just need flags for ZGC:
    #include "gc/z/z_globals.hpp"
- Future: subdivide globals.hpp into individual components:
  - (Not in this patch, but possible)
  - #include "memory/metaspaceShared_globals.hpp" // just flags related to CDS
Remove complex macros for flags manipulation
- Example: jvmFlags.cpp, globals_extension.hpp, jvmFlagRangeList.cpp
Hotspot command line switches should have multiple type attributes
- See JDK-7123237
  - E.g., one can have a "manageable" switch and an "experimental" switch, but not a "manageable_experimental" switch.
Templatize duplicated flag processing code:
- E.g., .jvmFlags.cpp
Speed up range/constraint checking for flags
- Avoid linear search for every -XX:NumericFlag=value argument in the command-line (jvmFlagRangeList.cpp)

(Design contribution by Erik Österlund, Stefan Karlsson, Coleen Phillimore)

...