Re: [PATCH] audo-detect and use -moutline-atomics compilation flag for aarch64

"Zidenberg, Tsahi" <tsahee(at)amazon(dot)com> writes:
> Outline-atomics is a gcc compilation flag that adds runtime detection of weather or not the cpu supports atomic instructions. CPUs that don't support atomic instructions will use the old load-exclusive/store-exclusive instructions. If a different compilation flag defined an architecture that unconditionally supports atomic instructions (e.g. -march=armv8.2), the outline-atomic flag will have no effect.

I wonder what version of gcc you intend this for. AFAICS, older
gcc versions lack this flag at all, while newer ones have it on
by default. Docs I can find on the net suggest that it would only
help to supply the flag when using gcc 10.0.x. Is there a sufficient
population of production systems using such gcc releases to make it
worth expending configure cycles on? (That's sort of a trick question,
because the GCC docs make it look like 10.0.x was never considered
to be production ready.)

regards, tom lane