Hi,
I'm working on the libatomic-ops (part of the Boehm gc) AArch64 support,
I mainly use GCC's __atomic builtins to do this, but in our 4.7 version
they don't use the load acquire / store release instructions now available
in the ARMv8 ISA. These instructions are used in the mainline GCC
(in atomic.md) but not in their exclusive form, I understand that it should
be due to the performance penalty, but I want your feeling on that point
as I don't find the ARMv8 ISA really clear.
If we want to implement an atomic load acquire, is
LDAR x1, [x0]
sufficient, or do we have to write it like that :
L: LDAXR x0, [x3]
STEX x1, x0, [x3]
CBZ x0, L1
Thanks
Yvan
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