RFR(S) 8240244 Avoid calling resolve_super_or_fail in SystemDictionary::load_shared_class

[Lois Foltan]

On 3/3/2020 1:34 AM, Ioi Lam wrote:
> https://bugs.openjdk.java.net/browse/JDK-8240244
> http://cr.openjdk.java.net/~iklam/jdk15/8240244-reduce-resolve-super.v01/
>
> When loading shared classes from the CDS archive, we need to test if the
> actually loaded super types are the same as those used during CDS 
> dumping.
> That was done with a pretty expensive call to resolve_super_or_fail.
>
> In most cases, the super type has already been loaded (about 350 out 
> of 400
> cases when running HelloWorld), so we can quickly determine that by
> doing a look up in the super type's dictionary.
>
> This saves about 250,000 out of about 112M instructions (about 0.22%) 
> when
> running HelloWorld with the default archive on Linux/x64.
>
> I also renamed a few functions in instanceKlass.hpp to _xxx_shared_xxx 
> since
> they are used only for CDS.
>
> Thanks
> - Ioi
>
>
Hi Ioi,

Looks good, I like the move to consolidate the calls to resolve_super or 
fail into SystemDictionary::check_shared_class_super_type().  I have a 
minor comment about checking the loader against NULL.

classfile/systemDictionary.cpp line #1266 & #1272, please consider using 
ClassLoaderData::is_the_boot_class_loader_data()

Thanks,
Lois