[clang] [llvm] [RISCV] Add experimental support of Zaamo and Zalrsc (PR #77424)

[Yingwei Zheng via cfe-commits]

dtcxzyw wrote:

> I guess Zaamo + Zacas is technically a way one could implement atomics without LR/SC?

The Zacas extension depends upon the A extension.


https://github.com/llvm/llvm-project/pull/77424