[PATCH] D47589: [RISCV] Add codegen support for atomic load/stores with RV32A

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Seems you're advocating that this patch (and the LangRef) follow the reality you'd like to have, not the one we actually have :-)

My description matches the way GNU libatomic works in practice, as far as I know.  (compiler-rt's implementation is incomplete and broken in other ways anyway; see https://reviews.llvm.org/D47606.)

> So I'll re-iterate: is the alignment check a documented guarantee that __atomic_* functions must provide, in all of their implementations?

The specialized forms (`__atomic_load_8` etc.) assume natural alignment, but the forms which take a size argument check alignment.  This is why `__atomic_is_lock_free` has a pointer argument. See  https://gcc.gnu.org/wiki/Atomic/GCCMM/LIbrary .


https://reviews.llvm.org/D47589