locking/atomic/x86: Introduce arch_try_cmpxchg64_local()

locking/atomic/x86: Introduce arch_try_cmpxchg64_local()

Introduce arch_try_cmpxchg64_local() for 64-bit and 32-bit targets
to improve code using cmpxchg64_local().  On 64-bit targets, the
generated assembly improves from:

    3e28:	31 c0                	xor    %eax,%eax
    3e2a:	4d 0f b1 7d 00       	cmpxchg %r15,0x0(%r13)
    3e2f:	48 85 c0             	test   %rax,%rax
    3e32:	0f 85 9f 00 00 00    	jne    3ed7 <...>

to:

    3e28:	31 c0                	xor    %eax,%eax
    3e2a:	4d 0f b1 7d 00       	cmpxchg %r15,0x0(%r13)
    3e2f:	0f 85 9f 00 00 00    	jne    3ed4 <...>

where a TEST instruction after CMPXCHG is saved.  The improvements
for 32-bit targets are even more noticeable, because double-word
compare after CMPXCHG8B gets eliminated.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20240414161257.49145-1-ubizjak@gmail.com