[master] RFR: Load narrowKlass from header, AArch64 assembler implementation [v3]

[Roman Kennke]

On Thu, 27 Jan 2022 14:36:25 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp line 596:
>> 
>>> 594:     // we have lock pointer bits in the upper 32bits. We can't get a false
>>> 595:     // negative.
>>> 596:     __ ldrw(r0, Address(r0, oopDesc::nklass_offset_in_bytes()));  // get klass
>> 
>> Something should assert that `oopDesc::nklass_offset_in_bytes()` does not break the alignment. Probably assert that `oopDesc::nklass_offset_in_bytes()` is a multiple of 4?
>
> `ldrw()` will definitely complain if it isn't.

Done that.

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PR: https://git.openjdk.java.net/lilliput/pull/36