RFR: 8315966: Relativize initial_sp in interpreter frames [v3]

[Fredrik Bredberg]

> Relativize initial_sp in interpreter frames.
> 
> By changing the "initial_sp" (AKA "monitor_block_top" or "monitors" on PowerPC) member in interpreter frames from being an absolute address into an offset that is relative to the frame pointer, we don't need to change the value as we freeze and thaw frames of virtual threads. This is since we might freeze and thaw from and to different worker threads, so the absolute address to locals might change, but the offset from the frame pointer will be constant.
> 
> This subtask only handles relativization of "initial_sp" and "monitor_block_top" since it's the same slot in interpreter frames (roughly the same as "monitors" on PowerPC). Relativization of other interpreter frame members are handled in other subtasks to JDK-8289296.
> 
> Tested tier1-tier7 on supported platforms. The rest was sanity tested using Qemu.

Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:

  Removed whitespace (RISC-V only).

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15815/files
  - new: https://git.openjdk.org/jdk/pull/15815/files/29b576fd..68d94c03

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15815&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15815&range=01-02

  Stats: 6 lines in 3 files changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/15815.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15815/head:pull/15815

PR: https://git.openjdk.org/jdk/pull/15815