RFR: Loom support for RedefineClasses

[Ron Pressler]

On Tue, 4 May 2021 17:29:34 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Use _marking_cycle to determine whether a Method* is on the heap.
> This patch includes the patches for https://github.com/openjdk/jdk/pull/3852 and https://git.openjdk.java.net/jdk/pull/3861 which are going to be pushed to mainline.

src/hotspot/share/oops/instanceStackChunkKlass.inline.hpp line 794:

> 792: void InstanceStackChunkKlass::run_nmethod_entry_barrier_if_needed(const StackChunkFrameStream<mixed>& f) {
> 793:   CodeBlob* cb = f.cb();
> 794:   if ((mixed && cb == nullptr) || !cb->is_nmethod()) {

If `mixed` is false, then there are no interpreted frames. The condition should be `if (f.is_interpreted())` (which short-circuits to false if `mixed` is false).

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PR: https://git.openjdk.java.net/loom/pull/38