RFR: 8349814: [leyden] Avoid uncommon traps in preload code [v2]

[Aleksey Shipilev]

> Preload code is the C2 code we load very early, before it gets substituted by more advanced C2 code. We are seeing lots of uncommon traps from the preloaded code, though, which invalidates it too early. We can do precompile code without uncommon traps to alleviate this. 
> 
> Additional testing:
>  - [x] Ad-hoc perf tests (see comment below)
>  - [x] Linux x86_64 server fastdebug, `runtime/cds`

Aleksey Shipilev 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 three additional commits since the last revision:

 - Merge branch 'premain' into JDK-8349814-preload-avoid-uncommon-traps
 - Comment
 - Fix

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

Changes:
  - all: https://git.openjdk.org/leyden/pull/38/files
  - new: https://git.openjdk.org/leyden/pull/38/files/04a27a7f..4051ce11

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=leyden&pr=38&range=01
 - incr: https://webrevs.openjdk.org/?repo=leyden&pr=38&range=00-01

  Stats: 24 lines in 6 files changed: 21 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/leyden/pull/38.diff
  Fetch: git fetch https://git.openjdk.org/leyden.git pull/38/head:pull/38

PR: https://git.openjdk.org/leyden/pull/38