[llvm] [X86]Add NO_REVERSE attribute to X86 RMW instrs in memfold table (PR #67288)

[Shengchen Kan via llvm-commits]

KanRobert wrote:

> X86 don't want to unfold RMW instrs to 1 load + 1 op + 1 store, because RMW could save code size. And from all the call position analysis, we could find we didn't unfold RMW in current code.

It's not only for code save. When the register pressure is very high, we can avoid clobbering one register by RMW.

https://github.com/llvm/llvm-project/pull/67288