RFR: Save/load nmethod without going through CodeBuffer

[Ashutosh Mehra]

This is the prototype for storing and loading nmethods without going through the CodeBuffer.
The new implementation is protected by the flag -XX:+UseNewCode2.

Some numbers using this implementation:
spring-boot-getting-started [0] shows startup improvement of ~ 7.5%% and quarkus-getting-started [1] shows improvement of around ~3.5%.

Numbers for Springboot

Old build = /home/asmehra/data/ashu-mehra/leyden/build/nmethod-single-copy-load-release/images/jdk with options -XX:+UnlockDiagnosticVMOptions -XX:-UseNewCode2
New build = /home/asmehra/data/ashu-mehra/leyden/build/nmethod-single-copy-load-release/images/jdk with options -XX:+UnlockDiagnosticVMOptions -XX:+UseNewCode2
Run,Old CDS + AOT,New CDS + AOT
1,544,512
2,554,525
3,550,508
4,571,515
5,550,506
6,552,515
7,568,510
8,554,517
9,551,506
10,556,508
Geomean,554.94,512.17
Stdev,7.90,5.65

Numbers for Quarkus:

Old build = /home/asmehra/data/ashu-mehra/leyden/build/nmethod-single-copy-load-release/images/jdk with options -XX:+UnlockDiagnosticVMOptions -XX:-UseNewCode2
New build = /home/asmehra/data/ashu-mehra/leyden/build/nmethod-single-copy-load-release/images/jdk with options -XX:+UnlockDiagnosticVMOptions -XX:+UseNewCode2
Run,Old CDS + AOT,New CDS + AOT
1,359,346
2,360,353
3,373,357
4,376,356
5,366,353
6,360,356
7,361,361
8,347,349
9,355,336
10,374,342
Geomean,363.00,350.82
Stdev,8.70,7.27


-Xlog:init logs the load time from AOT code cache at JVM exit.
For spring-boot-getting-started without `UseNewCode2`:

[3.459s][info][init]     SC Load Time:           0.202 s
[3.459s][info][init]       nmethod register:       0.135 s
[3.459s][info][init]       find cached code:       0.007 s


For spring-boot-getting-started with `UseNewCode2`:

[3.192s][info][init] 
[3.192s][info][init]     SC Load Time:           0.138 s
[3.192s][info][init]       nmethod register:       0.111 s
[3.192s][info][init]       find cached code:       0.006 s


For quarkus-getting-started without `UseNewCode2`

[0.392s][info][init]     SC Load Time:           0.060 s
[0.392s][info][init]       nmethod register:       0.039 s
[0.392s][info][init]       find cached code:       0.002 s


For quarkus-getting-started with `UseNewCode2`

[0.386s][info][init]     SC Load Time:           0.033 s
[0.386s][info][init]       nmethod register:       0.027 s
[0.386s][info][init]       find cached code:       0.002 s


[0] https://github.com/openjdk/leyden/tree/premain/test/hotspot/jtreg/premain/spring-boot-getting-started
[1] https://github.com/openjdk/leyden/tree/premain/test/hotspot/jtreg/premain/quarkus-getting-started

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

Commit messages:
 - Handle mutable nmethod data properly when storing/loading from AOT code
 - Fix win compile failures
 - Remove trailing whitespaces
 - Include os.hpp to fix compile failures
 - Store asm remarks and debug strings in the cache
 - More whitespace fixes
 - Fix whitespace errors; Some more cleanup
 - Fix compile failures in minimal build
 - Removed old code for storing/loading nmethods from AOT code cache
 - Store nmethod directly into AOT code cache
 - ... and 1 more: https://git.openjdk.org/leyden/compare/f57ae6a4...04b77eab

Changes: https://git.openjdk.org/leyden/pull/27/files
  Webrev: https://webrevs.openjdk.org/?repo=leyden&pr=27&range=00
  Stats: 1765 lines in 16 files changed: 1119 ins; 430 del; 216 mod
  Patch: https://git.openjdk.org/leyden/pull/27.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/27/head:pull/27

PR: https://git.openjdk.org/leyden/pull/27