Integrated: 8299079: Better interface nmethod oop accesses

[Erik Österlund]

On Tue, 20 Dec 2022 08:29:09 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

> Today when oops are read from nmethods, we use the same interfacing that we would use to read any other IN_NATIVE oops. That isn't enough for generational ZGC. The nmethod oops are rather different from other IN_NATIVE oops in that they are encoded in the machine code as direct pointers. Normally, IN_NATIVE oops with generational ZGC are not direct pointers, but are colored pointered that can be converted to direct pointers by going through a load barrier. For nmethod oops, that conversion requires external knowledge from the surrounding nmethod. I propose a new NMethodAccess to interface better with the GC.

This pull request has now been integrated.

Changeset: e3035bad
Author:    Erik Österlund <eosterlund at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/e3035bad60dfa71e9c24fcc509cd7f07eb2bf62e
Stats:     25 lines in 3 files changed: 8 ins; 0 del; 17 mod

8299079: Better interface nmethod oop accesses

Co-authored-by: Axel Boldt-Christmas <aboldtch at openjdk.org>
Reviewed-by: kvn, dholmes

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PR: https://git.openjdk.org/jdk/pull/11738