Save/load nmethod without going through CodeBuffer

[ashu-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

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Progress

• Change must not contain extraneous whitespace
• Change must be properly reviewed (1 review required, with at least 1 Committer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/leyden.git pull/27/head:pull/27
$ git checkout pull/27

Update a local copy of the PR:
$ git checkout pull/27
$ git pull https://git.openjdk.org/leyden.git pull/27/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 27

View PR using the GUI difftool:
$ git pr show -t 27

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/leyden/pull/27.diff

[bridgekeeper]

👋 Welcome back asmehra! A progress list of the required criteria for merging this PR into premain will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[ashu-mehra]

@adinn @vnkozlov fyi