RFR: Save/load nmethod without going through CodeBuffer [v6]

[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/op...

Ashutosh Mehra 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 17 additional commits since the last revision:

 - Merge branch 'premain' into nmethod-single-copy-load
 - Rename write_nmethod_extra_relocations to write_nmethod_loadtime_relocations
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Flush code block when loading the nmethod from archive
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Some more cleanup
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Set compile id
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Minor cleanup
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Handle mutable nmethod data properly when storing/loading from AOT code
   cache
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Fix win compile failures
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Remove trailing whitespaces
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - Include os.hpp to fix compile failures
   
   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>
 - ... and 7 more: https://git.openjdk.org/leyden/compare/efccd77f...45b086ad

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

Changes:
  - all: https://git.openjdk.org/leyden/pull/27/files
  - new: https://git.openjdk.org/leyden/pull/27/files/14a44f83..45b086ad

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=27&range=05
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=27&range=04-05

  Stats: 147 lines in 16 files changed: 75 ins; 47 del; 25 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