[clang] [llvm] [LoongArch] Support amcas[_db].{b/h/w/d} instructions. (PR #114189)

[Lu Weining via cfe-commits]

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@@ -5722,6 +5726,58 @@ bool LoongArchTargetLowering::getTgtMemIntrinsic(IntrinsicInfo &Info,
   }
 }
 
+void LoongArchTargetLowering::emitExpandAtomicRMW(AtomicRMWInst *AI) const {
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SixWeining wrote:

Please add some comments for this func and add a test (ir -> ir).

https://github.com/llvm/llvm-project/pull/114189