On Thu, 13 Oct 2022 at 20:31, Vineet Gupta wrote:
>
> Hi,
>
> I have a testcase (from real workloads) involving C++ atomics and trying
> to understand the codegen (gcc 12) for RVWMO and x86.
> It does mix atomics with non-atomics so not obvious what the behavior is
> intended to be hence some explicit CC of subject matter experts
> (apologies for that in advance).
>
> Test has a non-atomic store
And a non-atomic load of 'g'
> followed by an atomic_load(SEQ_CST). I
> assume that unadorned direct access defaults to safest/conservative seq_cst.
Yes, the two functions below are identical.
>
> extern int g;
> std::atomic<int> a;
>
> int bar_noaccessor(int n, int *n2)
> {
> *n2 = g;
> return n + a;
> }
>
> int bar_seqcst(int n, int *n2)
> {
> *n2 = g;
> return n + a.load(std::memory_order_seq_cst);
> }
>
