WIP: C1+C2 AOT + C1 JIT hybrid

[shipilev]

Includes #93.

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Progress

• [x] 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/96/head:pull/96
$ git checkout pull/96

Update a local copy of the PR:
$ git checkout pull/96
$ git pull https://git.openjdk.org/leyden.git pull/96/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 96

View PR using the GUI difftool:
$ git pr show -t 96

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/leyden/pull/96.diff

[shipilev]

Sample perf result:

Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xms64m -Xmx1g -XX:+UseSerialGC \
  -XX:AOTCache=app.aot \
  -cp JavacBenchApp.jar JavacBenchApp 50
  Time (mean ± σ):     454.5 ms ±   4.2 ms    [User: 1098.7 ms, System: 128.3 ms]
  Range (min … max):   447.1 ms … 462.7 ms    30 runs
 
Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xms64m -Xmx1g -XX:+UseSerialGC \
  -XX:AOTCache=app.aot -XX:TieredStopAtLevel=1 \
  -cp JavacBenchApp.jar JavacBenchApp 50
  Time (mean ± σ):     429.7 ms ±   3.0 ms    [User: 458.9 ms, System: 63.9 ms]
  Range (min … max):   424.2 ms … 437.5 ms    30 runs
 
Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xms64m -Xmx1g -XX:+UseSerialGC \
  -XX:AOTCache=app.aot -XX:+UnlockExperimentalVMOptions -XX:+PreloadOnly \
  -cp JavacBenchApp.jar JavacBenchApp 50
  Time (mean ± σ):     430.6 ms ±   2.5 ms    [User: 434.8 ms, System: 60.6 ms]
  Range (min … max):   425.9 ms … 437.4 ms    30 runs
 
Benchmark 1: build/linux-x86_64-server-release/images/jdk/bin/java -Xms64m -Xmx1g -XX:+UseSerialGC \
  -XX:AOTCache=app.aot -XX:+UnlockExperimentalVMOptions -XX:+PreloadAndC1Only  \
  -cp JavacBenchApp.jar JavacBenchApp 50
  Time (mean ± σ):     340.5 ms ±   2.3 ms    [User: 406.8 ms, System: 68.2 ms]
  Range (min … max):   337.0 ms … 345.5 ms    30 runs

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