[llvm] [RISCV] Initial ISel support for the experimental zacas extension (PR #67918)

[Yingwei Zheng via llvm-commits]

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@@ -728,6 +807,72 @@ bool RISCVExpandAtomicPseudo::expandAtomicCmpXchg(
   return true;
 }
 
+static Register getGPRPairEvenReg(Register PairedReg) {
+  switch (PairedReg) {
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dtcxzyw wrote:

I will push my local changes later.


https://github.com/llvm/llvm-project/pull/67918