[llvm] [RISCV] Fold (add (srl x, n), (srl x, n)) into (srl x, n-1) (PR #144507)

[Craig Topper via llvm-commits]

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@@ -15240,12 +15240,42 @@ static SDValue combineAddOfBooleanXor(SDNode *N, SelectionDAG &DAG) {
                      N0.getOperand(0));
 }
 
+// Try to turn (add (srl x, n), (srl x, n)) into (srl x, n-1).
+//
+// This combine could perhaps be moved to DAGCombiner. For RISCV this kind of
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topperc wrote:

RISCV should be spelled RISC-V in comments. It's a trademark.

https://github.com/llvm/llvm-project/pull/144507