RFR: 8308984: Relativize last_sp (and top_frame_sp) in interpreter frames

[Patricio Chilano Mateo]

On Mon, 19 Jun 2023 15:59:15 GMT, Fredrik Bredberg <fbredberg at openjdk.org> wrote:

> Implementation of relativized last_sp (top_frame_sp on PowerPC) in interpreter frames for x64, aarch64, ppc64le and riscv.
> Not relativized last_sp on arm, zero and s390 but done some changes to cope with the changed generic code.
> 
> By changing the "last_sp" 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 "last_sp" (and its close equivalent "top_frame_sp" on PowerPC). The 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.

src/hotspot/share/runtime/continuationFreezeThaw.cpp line 817:

> 815:         return freeze_pinned_native;
> 816:       }
> 817:       prepare_freeze_interpreted_top_frame(f);

Probably better to handle setting last_sp for this special case in freeze_start_frame_safepoint_stub(). But in any case the preemption code is not there yet so I would just remove these changes and prepare_freeze_interpreted_top_frame().

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PR Review Comment: https://git.openjdk.org/jdk/pull/14545#discussion_r1279896849