RFR: 8262508: Vector API's ergonomics is incorrect [v2]

[Jie Fu]

> Hi all,
> 
> The ergonomics (e.g., EnableVectorReboxing/EnableVectorAggressiveReboxing) for Vector API doesn't work as expected.
> 
> There are two sets of rules for Vector API.
> One is in Arguments::apply_ergo() [1], which sets the flags to be false.
> And the other is in Modules::define_module() [2], which sets the flags to be true.
> 
> The value of EnableVectorReboxing and EnableVectorAggressiveReboxing may be changed (from specified true to false) in [1] if EnableVectorSupport=false (which is the default value).
> It would be wrong when EnableVectorSupport isn't specified in the command line since it will be set true later in [2]
> So rules in [1] should not be executed if EnableVectorSupport isn't specified.
> 
> Thanks.
> Best regards,
> Jie
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/runtime/arguments.cpp#L4081
> [2] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/classfile/modules.cpp#L462

Jie Fu has updated the pull request incrementally with one additional commit since the last revision:

  Require C2 to run the test

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2771/files
  - new: https://git.openjdk.java.net/jdk/pull/2771/files/5563b0cc..517d2d3f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2771&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2771&range=00-01

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2771.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2771/head:pull/2771

PR: https://git.openjdk.java.net/jdk/pull/2771