> The proposal is to encapsulate the nmethod mark for deoptimization logic in
> one place and only allow access to the `mark_for_deoptimization` from a
> closure object:
> ```C++
> class DeoptimizationMarkerClosure : StackObj {
> public:
> virtual void marker_do(Deoptimization::MarkFn mark_fn) = 0;
> };
>
> This closure takes a `MarkFn` which it uses to mark which nmethods should be
> deoptimized. This marking can only be done through the `MarkFn` and a
> `MarkFn` can only be created in the following code which runs the closure.
> ```C++
> {
> NoSafepointVerifier nsv;
> assert_locked_or_safepoint(Compile_lock);
> marker_closure.marker_do(MarkFn());
> anything_deoptimized = deoptimize_all_marked();
> }
> if (anything_deoptimized) {
> run_deoptimize_closure();
> }
>
> This ensures that this logic is encapsulated and the `NoSafepointVerifier`
> and `assert_locked_or_safepoint(Compile_lock)` makes `deoptimize_all_marked`
> not having to scan the whole code cache sound.
>
> The exception to this pattern, from `InstanceKlass::unload_class`, is
> discussed in the JBS issue, and gives reasons why not marking for
> deoptimization there is ok.
>
> An effect of this encapsulation is that the deoptimization logic was moved
> from the `CodeCache` class to the `Deoptimization` class and the class
> redefinition logic was moved from the `CodeCache` class to the
> `VM_RedefineClasses` class/operation.
>
> Testing: Tier 1-5
>
> _Update_
> ---
> Switched too using a RAII object to track the context instead of putting code
> in a closure. But all the encapsulation is still the same.
>
> Testing: Tier 1-7
>
> _Update_
> ---
>> @stefank suggested splitting out unloading klass logic change into a
>> separate issue [JDK-8291718](https://bugs.openjdk.org/browse/JDK-8291718).
>>
>> Will probably also limit this PR to only encapsulation. (Skipping the linked
>> list optimisation) And create a separate issue for that as well.
>>
>> But this creates a chain of three dependent issues.
>> [JDK-8291237](https://bugs.openjdk.org/browse/JDK-8291237) depends on
>> [JDK-8291718](https://bugs.openjdk.org/browse/JDK-8291718). And the link
>> list optimisation depend will depend on
>> [JDK-8291237](https://bugs.openjdk.org/browse/JDK-8291237).
>>
>> Will mark this as a draft for now and create a PR for
>> [JDK-8291718](https://bugs.openjdk.org/browse/JDK-8291718) first.
Axel Boldt-Christmas has updated the pull request incrementally with one
additional commit since the last revision:
Add list optimization
-------------
Changes:
- all: https://git.openjdk.org/jdk/pull/9655/files
- new: https://git.openjdk.org/jdk/pull/9655/files/2be7b152..bea67dea
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=9655&range=04
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=9655&range=03-04
Stats: 65 lines in 3 files changed: 50 ins; 1 del; 14 mod
Patch: https://git.openjdk.org/jdk/pull/9655.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/9655/head:pull/9655
PR: https://git.openjdk.org/jdk/pull/9655
