RFR: 8253920: Share method trampolines in CDS dynamic archive

[Claes Redestad]

On Mon, 26 Oct 2020 18:12:16 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

> This patch is to allow sharing of the same method trampoline for archived Methods with the same AdapterHandleEntry when using CDS dynamic archive. 
> 
> Running javac on HelloWorld with CDS dynamic archive, the number of calls to SharedRuntime::generate_trampoline() is reduced to 406 times vs 12601 times without the patch.
> 
> In terms of saving on instructions and time (on linux-x64):
> instr delta =     -2807662    -0.1369%
> time  delta =       -6.860 ms -1.8798%
> 
> It passed tiers 1,2,3,4 testing.

LGTM

Thanks for ensuring static data-structures only used when dumping are lazily allocated.

src/hotspot/share/classfile/systemDictionaryShared.cpp line 1189:

> 1187:   ResourceObj::C_HEAP> {};
> 1188: 
> 1189: static LoadedUnregisteredClassesTable* _loaded_unregistered_classes = NULL;

Good!

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Marked as reviewed by redestad (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/868