litmus test

Litmus Test: ES2017 racy reads on ARMv8
Can this program (using atomics) see r1 = 0, r2 = 1?
// Thread 1           // Thread 2
x = 1                 y = 1
r1 = y                x = 2 (non-atomic)
					  r2 = x
C++: yes (data race, can do anything at all).
Java: the program cannot be written.
ARMv8 using ldar/stlr: yes.
ES2017: no! (contradicting ARMv8)