[MLIR][Arith] add and(a, or(a,b)) folder

Author: wsmoses

mlir/lib/Dialect/Arith/IR/ArithOps.cpp

@@ -896,6 +896,18 @@ OpFoldResult arith::AndIOp::fold(FoldAdaptor adaptor) {
   if (Value result = foldAndIofAndI(*this))
     return result;
 
+  /// and(a, or(a, b)) -> a
+   for (int i = 0; i < 2; i++) {
+     auto a = getOperand(1 - i);
+     if (auto orOp = getOperand(i).getDefiningOp<arith::OrIOp>()) {
+       for (int j = 0; j < 2; j++) {
+         if (orOp->getOperand(j) == a) {
+           return a;
+         }
+       }
+     }
+   }
+
   return constFoldBinaryOp<IntegerAttr>(
       adaptor.getOperands(),
       [](APInt a, const APInt &b) { return std::move(a) & b; });