RFR: 8257423: [PPC64] Support -XX:-UseInlineCaches

[Martin Doerr]

On Tue, 1 Dec 2020 17:01:28 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> The JVM currently runs into Unimplemented() when using -XX:-UseInlineCaches in C2 code (postalloc_expand_java_dynamic_call_sched).
>> I'd like to enable the existing code in postalloc_expand_java_dynamic_call_sched and fix MachCallDynamicJavaNode::ret_addr_offset() and MacroAssembler::instr_size_for_decode_klass_not_null().
>> I suggest to use scratch emit to determine the size, because there are too many cases and emitting it once is fast.
>
> src/hotspot/cpu/ppc/macroAssembler_ppc.cpp line 3166:
> 
>> 3164:       // Determine by scratch emit.
>> 3165:       ResourceMark rm;
>> 3166:       int code_size = 8 * BytesPerInstWord;
> 
> Is this enough? Can CodeBuffers expand?

Maximum size is 7 instructions.

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PR: https://git.openjdk.java.net/jdk/pull/1521