[llvm] [RISCV][NFC] Avoid iteration and division while selecting SHXADD instructions (PR #158851)

[Craig Topper via llvm-commits]

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@@ -25,6 +25,22 @@
 
 namespace llvm {
 
+template <typename T> int isShifted359(T Value, int &Shift) {
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topperc wrote:

Add a description comment??

https://github.com/llvm/llvm-project/pull/158851