RFR: 8305895: Implementation: JEP 450: Compact Object Headers (Experimental) [v11]

[Roman Kennke]

On Thu, 11 May 2023 22:50:20 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Fix some uses of klass_offset_in_bytes()
>>  - Fix args checking
>
> src/hotspot/cpu/x86/c1_MacroAssembler_x86.cpp line 186:
> 
>> 184:   if (len->is_valid()) {
>> 185:     movl(Address(obj, arrayOopDesc::length_offset_in_bytes()), len);
>> 186:     if (UseCompactObjectHeaders) {
> 
> This should also be in _LP64 and not have && !UseCompactObjectHeaders. You should restrict this to LP64 in this change.

Ok I will put it in _LP64 (even though it is not strictly needed - UseCompactObjectHeaders is hard-wired constant false, so compiler will not include the code, I would expect), but why not check UseCompactObjectHeaders here? The new code is only sensible with compact headers.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/13844#discussion_r1192591711