arm64: Implement Unsafe.compareAndSetObject intrinsic.
Also fix a few copy-paste errors in comments for x86/x86_64.
The implementation is the same as Unsafe.compareAndSwapObject, as the
latter operation has compare-and-set semantics.
Benchmarks improvements (using benchmarks provided by
https://android-review.googlesource.com/1420959):
benchmark before after
-----------------------------------------------------
UnsafeCompareAndSetStaticFieldString 3.908 0.014
UnsafeCompareAndSetFieldString 3.917 0.014
Bug: 71781600
Bug: 202868177
Test: art/test.py --target -r -t 712-varhandle-invocations --64
Change-Id: I799f47210f8b70d6944418c05b985fe678f36208
4 files changed
