RFR: 8267870: Remove unnecessary char_converter during class loading

[Coleen Phillimore]

On Tue, 15 Jun 2021 03:10:12 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> We create a String object from a Symbol, then swap the '/' for '.' characters, and create another String object.  Seems wasteful.  Removed java_lang_String::char_converted and made externalize_classname take a Symbol.
>> 
>> Tested with tier1-3 in mach5.
>
> src/hotspot/share/classfile/javaAssertions.cpp line 139:
> 
>> 137:   for (index = len - 1; p != 0; p = p->next(), --index) {
>> 138:     assert(index >= 0, "length does not match list");
>> 139:     TempNewSymbol name = SymbolTable::new_symbol(p->name());
> 
> Why do we need a temp symbol?

Because the new_symbol call will increment the Symbol* refcount in the SymbolTable, it's then copied to the java.lang.String, so the name isn't needed after this.

> src/hotspot/share/classfile/javaClasses.hpp line 231:
> 
>> 229: 
>> 230:   // Conversion between '.' and '/' formats, and allocate a String from the result.
>> 231:   static Handle externalize_classname(Symbol* java_string, TRAPS);
> 
> Nit: java_name might be more apt.

Done!

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PR: https://git.openjdk.java.net/jdk/pull/4173