[llvm] [RISCV] Add combine for shadd family of instructions. (PR #130829)

[Stefan Pintilie via llvm-commits]

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@@ -50,6 +51,7 @@
 #include <optional>
 
 using namespace llvm;
+using namespace llvm::PatternMatch;
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stefanp-synopsys wrote:

Oh wow! I may have just create this problem for myself. Let me remove  that line. 
Thank you!

https://github.com/llvm/llvm-project/pull/130829