RFR: 8315966: Relativize initial_sp in interpreter frames

[Fei Yang]

On Tue, 19 Sep 2023 09:00:01 GMT, Fredrik Bredberg <fbredberg at openjdk.org> wrote:

> 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.

Hi, I have arranged tier1-3 test on linux-riscv64 platform. Thanks for adding handling for riscv.

src/hotspot/cpu/riscv/interp_masm_riscv.cpp line 704:

> 702:     // register for unlock_object to pass to VM directly
> 703:     ld(c_rarg1, monitor_block_top); // derelativize pointer
> 704:     shadd(c_rarg1, c_rarg1, fp,  c_rarg1, LogBytesPerWord);

Nit: One redundant space between the 3rd and 4th parameters for each `shadd` call added.

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PR Review: https://git.openjdk.org/jdk/pull/15815#pullrequestreview-1635063095
PR Review Comment: https://git.openjdk.org/jdk/pull/15815#discussion_r1331261765