[clang] [clang][CodeGen] Emit improved memory effects and return status for AsmStmt (PR #110510)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic commented:

We need documentation for the exact assumptions we're making here.

Distinguishing between "volatile" and a "memory clobber" seems a bit aggressive... I mean, I'm not sure what gcc does here, but it seems like an extremely subtle distinction.  Same with marking outputs "mod".

Do we want nocapture markings on memory operands?

I'd like to see more test coverage here, particularly for asm statements that have both memory operands and volatile/clobbers.

https://github.com/llvm/llvm-project/pull/110510