[lworld] RFR: Merge jdk [v2]

[David Simms]

> Merge tag 'jdk-20+21' into lworld_merge_jdk_20_21
> 
> # Conflicts:
> #	src/hotspot/share/oops/constantPool.cpp
> #	src/hotspot/share/oops/method.cpp
> #	src/hotspot/share/oops/method.hpp
> #	src/hotspot/share/runtime/sharedRuntime.cpp
> #	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
> #	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java

David Simms has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 1459 commits:

 - Merge tag 'jdk-20+21' into lworld_merge_jdk_20_21
   
   Added tag jdk-20+21 for changeset 46e6aee0
   
   # Conflicts:
   #	src/hotspot/share/oops/constantPool.cpp
   #	src/hotspot/share/oops/method.cpp
   #	src/hotspot/share/oops/method.hpp
   #	src/hotspot/share/runtime/sharedRuntime.cpp
   #	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Lower.java
   #	src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Resolve.java
 - 8295086: [lworld] follow-up for JDK-8288131
 - Merge jdk
   
   Merge tag 'jdk-20+20'
 - 8224057: [lworld] a hidden value class can't have <vnew> static factory method
 - 8295735: [lworld] Missing membar after buffer initialization in method handle return
 - 8295731: [lworld] C1's linear register allocator spill map is incorrect
 - 8247569: [lworld] Align with spec for <vnew> methods
   8294224: [lworld] VM support for <vnew> factory methods
   
   Co-authored-by: Vicente Romero <vromero at openjdk.org>
   Co-authored-by: Harold Seigel <hseigel at openjdk.org>
   Co-authored-by: Mandy Chung <mchung at openjdk.org>
   Reviewed-by: fparain, mchung
 - 8295655: [lworld] AArch64: Deoptimization from return value stub fails
 - 8295455: [lworld] find_callee_info_helper hits "must have non-abstract attached method" assert
 - 8281295: Prototype serialization/deserialization using Unsafe.
   
   Reviewed-by: mchung
 - ... and 1449 more: https://git.openjdk.org/valhalla/compare/46e6aee0...ef135072

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

Changes: https://git.openjdk.org/valhalla/pull/801/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=801&range=01
  Stats: 195499 lines in 1605 files changed: 186587 ins; 2175 del; 6737 mod
  Patch: https://git.openjdk.org/valhalla/pull/801.diff
  Fetch: git fetch https://git.openjdk.org/valhalla pull/801/head:pull/801

PR: https://git.openjdk.org/valhalla/pull/801