RFR: 8301992: Embed SymbolTable CHT node [v4]

[Calvin Cheung]

On Thu, 16 Feb 2023 19:52:31 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> How about performing the above check at the beginning of the function, right after the assert statement as follows?
>> Let me know if the added assert is necessary.
>> 
>> --- a/src/hotspot/share/classfile/symbolTable.cpp
>> +++ b/src/hotspot/share/classfile/symbolTable.cpp
>> @@ -151,6 +151,13 @@ public:
>>      // If #2, then the symbol is dead (refcount==0)
>>      assert(value.is_permanent() || (value.refcount() == 1) || (value.refcount() == 0),
>>             "refcount %d", value.refcount());
>> +#if INCLUDE_CDS
>> +    if (DumpSharedSpaces) {
>> +      assert(value.is_permanent(), "symbol should be permanent during CDS dumping");
>> +      // no deallocation is needed
>> +      return;
>> +    }
>> +#endif
>>      if (value.refcount() == 1) {
>>        value.decrement_refcount();
>>        assert(value.refcount() == 0, "expected dead symbol");
>
> Currently, in `allocate_node_impl()` there's no guarantee that the refcount is always permanent when DumpSharedSpaces is true.
> 
> During CDS dumping, some classes may be loaded by non-boot loaders, and their symbols may initially have a non-permanent count. Eventually, we force all the archived symbols to be permanent, but theoretically calls to `free_node()` may happen before that.

Ok. I've pushed a commit without the assert statement.

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PR: https://git.openjdk.org/jdk/pull/12562