RFR: 8309390: [JVMCI] improve copying system properties into libgraal [v3]

[Doug Simon]

> This PR improves the startup time for libgraal by speeding up how `VM.savedProps` is copied into libgraal. This data structure is now serialized to a native buffer directly from C++ and the native buffer is then directly decoded by libgraal.
> 
> ## Times
> 
> The basic benchmarking below shows that this change brings the time for a nop Java app with eager libgraal initialization (2) down to almost the same time as lazy libgraal initialization (1). The latter typically means no libgraal initialization happens as a top tier JIT compilation is never scheduled in such a short running app.
> 
> 
> public class Nop {
>     public static void main(String[] args) {}
> }
> 
> 
> (1) Baseline (no options):
> 
>> for i in (seq 10); java Nop; end
>         0.05 real         0.04 user         0.01 sys
>         0.04 real         0.03 user         0.01 sys
>         0.04 real         0.03 user         0.01 sys
>         0.04 real         0.03 user         0.01 sys
>         0.03 real         0.03 user         0.00 sys
>         0.04 real         0.03 user         0.01 sys
>         0.04 real         0.03 user         0.00 sys
>         0.03 real         0.03 user         0.00 sys
>         0.04 real         0.03 user         0.01 sys
>         0.03 real         0.03 user         0.00 sys
> 
> 
> (2) Eagerly initialize libgraal (with PR):
> 
>> for i in (seq 10); /usr/bin/time java -XX:+EagerJVMCI Nop; end
>         0.06 real         0.04 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
>         0.05 real         0.03 user         0.01 sys
> 
> 
> (3) Eagerly initialize libgraal (without PR):
> 
>> for i in (seq 10); /usr/bin/time java -XX:+EagerJVMCI Nop; end
>         0.11 real         0.08 user         0.02 sys
>         0.08 real         0.06 user         0.01 sys
>         0.08 real         0.07 user         0.01 sys
>         0.10 real         0.07 user         0.01 sys
>         0.08 real         0.06 user         0.01 sys
>         0.10 real         0.07 user         0.01 sys
>         0.08 real         0.07 user         0.01 sys
>         0.08 real         0.07 user         0.01 sys
>         0.08 real         0.06 user         0.01 sys
>         0.08 real  ...

Doug Simon has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains one additional commit since the last revision:

  copy system properties into libgraal more efficiently

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14291/files
  - new: https://git.openjdk.org/jdk/pull/14291/files/c3c04749..7a82c24e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14291&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14291&range=01-02

  Stats: 26320 lines in 384 files changed: 24869 ins; 633 del; 818 mod
  Patch: https://git.openjdk.org/jdk/pull/14291.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14291/head:pull/14291

PR: https://git.openjdk.org/jdk/pull/14291