[lworld] RFR: 8366973: [lworld] Deopt/recompilation cycle due to call to method with unloaded return type [v2]

[Tobias Hartmann]

> In some benchmarks we hit an endless deopt/recompilation cycle because of this bailout in C2 when we compile a method with an unloaded return type:
> https://github.com/openjdk/valhalla/blob/858be30119bd5bc37a69d16042523f53bea71a36/src/hotspot/share/ci/ciTypeFlow.cpp#L766-L772
> 
> It's a regression / limitation from [JDK-8301007](https://bugs.openjdk.org/browse/JDK-8301007) that I had planned to fix later with [JDK-8284443](https://bugs.openjdk.org/browse/JDK-8284443) because I thought it wouldn't have an impact on performance. Turns out it does, so I'll fix it with this issue similar to what we do in `PhaseMacroExpand::expand_mh_intrinsic_return`.
> 
> For testing, I added a new `PreloadClasses` debug flag that's enabled by default. Disabling it will disable preloading of all classes from the LoadableDescriptors attributes. Running testing with this caught some more issues that I fixed in this PR as well. I'll add it to our (internal) stress testing job separately.
> 
> I also fixed some inconsistency in the preload logging and adjusted the corresponding tests.
> 
> Thanks,
> Tobias

Tobias Hartmann has updated the pull request incrementally with one additional commit since the last revision:

  Increased timeouts

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

Changes:
  - all: https://git.openjdk.org/valhalla/pull/1554/files
  - new: https://git.openjdk.org/valhalla/pull/1554/files/ba000c21..a89812ee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=valhalla&pr=1554&range=01
 - incr: https://webrevs.openjdk.org/?repo=valhalla&pr=1554&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1554.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1554/head:pull/1554

PR: https://git.openjdk.org/valhalla/pull/1554