[clang] [llvm] [inlineasm] Add special support for "rm" inline asm constraints (PR #181973)

[Nikita Popov via cfe-commits]

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nikic wrote:

Maybe I missed it, but are there any tests where (at `-O2`) we actually fall back to the m constraint? It looks like everything here uses registers (or explicit `m` constraints).

https://github.com/llvm/llvm-project/pull/181973