RFR: 8263002: Remove CDS MiscCode region [v2]

[Ioi Lam]

On Mon, 8 Mar 2021 23:50:30 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Ioi Lam has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - bumped CURRENT_CDS_ARCHIVE_VERSION by one since format has changed
>>  - @coleenp review: remove temp debug code; fixed accounting of vtable sizes
>
> src/hotspot/share/memory/archiveBuilder.cpp line 831:
> 
>> 829:       if (STATIC_DUMP) {
>> 830:         if (!_builder->is_in_buffer_space(*p)) {
>> 831:           tty->print_cr("ohashii %p %p", p, *p);
> 
> What is ohashii ?  Should this be an assert?  Or log_error instead of tty->print

This was debug code that I left behind by mistake. I've removed it.

> src/hotspot/share/memory/cppVtables.cpp line 218:
> 
>> 216:   assert(DumpSharedSpaces, "must");
>> 217:   size_t vtptrs_bytes = _num_cloned_vtable_kinds * sizeof(CppVtableInfo*);
>> 218:   _index = (CppVtableInfo**)ArchiveBuilder::current()->rw_region()->allocate(vtptrs_bytes);
> 
> I thought these would be read-only?

The vtables contain function pointers and need to be updated at runtime to match the latest location of libjvm.so, so they need to be R/W.

> src/hotspot/share/memory/dumpAllocStats.cpp line 106:
> 
>> 104: 
>> 105:   assert(all_ro_bytes == ro_all, "everything should have been counted");
>> 106: //assert(all_rw_bytes == rw_all, "everything should have been counted"); FIXME!
> 
> ? Does this need to be fixed?

This is fixed in the latest version. I added accounting for the vtables.

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PR: https://git.openjdk.java.net/jdk/pull/2861