Integrated: 8289925: Shared code shouldn't reference the platform specific method frame::interpreter_frame_last_sp()

[Richard Reingruber]

On Thu, 7 Jul 2022 16:02:19 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

> The method `frame::interpreter_frame_last_sp()` is a platform method in the sense that it is not declared in a shared header file. It is declared and defined on some platforms though (x86 and aarch64 I think).
> 
> `frame::interpreter_frame_last_sp()` existed on these platforms before vm continuations (aka loom). Shared code that is part of the vm continuations implementation references it. This breaks the platform abstraction.
> 
> Using unextended_sp is problematic too because there are no guarantees by the platform abstraction layer for it. In fact unextended_sp < sp is possible on ppc64 and aarch64.
> 
> This fix changes the callers of is_sp_in_continuation()
> 
> ```c++
> static inline bool is_sp_in_continuation(const ContinuationEntry* entry, intptr_t* const sp) {
>   return entry->entry_sp() > sp;
> }
> 
> 
> to pass the actual sp. This is correct because the following is true on all platforms:
> 
> ```c++
> a.sp() > E->entry_sp() > b.sp() > c.sp()
> 
> 
> where `a`, `b`, `c` are stack frames in call order and `E` is a ContinuationEntry. `a` is the caller frame of the continuation entry frame that corresponds to `E`.
> 
> is_sp_in_continuation() will then return true for `b.sp()` and `c.sp()` and false for `a.sp()`
> 
> Testing: hotspot_loom and jdk_loom on x86_64 and aarch64.

This pull request has now been integrated.

Changeset: ee6c3917
Author:    Richard Reingruber <rrich at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/ee6c39175bc47608282c52c575ce908399349e7c
Stats:     31 lines in 7 files changed: 5 ins; 22 del; 4 mod

8289925: Shared code shouldn't reference the platform specific method frame::interpreter_frame_last_sp()

Reviewed-by: eosterlund, dlong

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PR: https://git.openjdk.org/jdk/pull/9411