On Fri, 11 Feb 2022 08:05:30 GMT, Peter Levart <plev...@openjdk.org> wrote:
>> liach has updated the pull request incrementally with one additional commit
>> since the last revision:
>>
>> Make config a pojo, move loading code into config class
>
> src/java.base/share/classes/jdk/internal/reflect/ReflectionFactory.java line
> 685:
>
>> 683: instance = c = load();
>> 684: }
>> 685: return c;
>
> If you do that the "old" way, you loose the ability for JIT to constant-fold
> the `instance` and by transitivity the Config instance fields, since the
> check for `VM.isModuleSystemInited()` can't be elided. As suggested, the
> fast-path check should be done 1st, like:
>
>
> private static @Stable Config instance;
>
> private static Config instance() {
> Config c = instance;
> if (c != null) {
> return c;
> }
>
> // Defer initialization until module system is initialized so as
> // to avoid inflation and spinning bytecode in unnamed modules
> // during early startup.
> if (!VM.isModuleSystemInited()) {
> return DEFAULT;
> }
>
> instance = c = load();
> return c;
> }
...having suggested that rearrangement, perhaps the right way to do it is to
enable some VM.isXXX queries themselves to be constant-foldable so that other
callers too may benefit. Like this:
https://github.com/plevart/jdk/commit/e918ccc52bbc288f6721af5fa66d8f7a8cc880cf
WDYT?
-------------
PR: https://git.openjdk.java.net/jdk/pull/6889
