[PIR][DynamicShape] Add strategy for compatibility in select_input op (…

…#62381)

Add strategy for compatibility in select_input op

paddle/fluid/pir/dialect/operator/ir/control_flow_op.cc

@@ -999,19 +999,20 @@ bool SelectInputOp::InferSymbolicShape(
   const auto &input1_dims = GetSymExprForValue(operand_source(0));
   const auto &input2_dims = GetSymExprForValue(operand_source(1));
 
+  // for compatibility, we just return second_shape.
+  if (input1_dims.size() != input2_dims.size()) {
+    shape_analysis->SetShapeOrDataForValue(
+        result(0),
+        symbol::ShapeOrDataDimExprs{
+            symbol::TensorShapeOrDataDimExprs(input2_dims)});
+    return true;
+  }
+
   std::vector<symbol::DimExpr> out_dims = input1_dims;
   // merge shape for input1 and input2, since we don't know which will be
   // selected in compile time, the strategy is same with IfOp, see IfOp's
   // comments for details and examples
   if (input2_dims.size() != 0) {
-    // now only support input1 and input2 have same rank.
-    PADDLE_ENFORCE_EQ(input1_dims.size(),
-                      input2_dims.size(),
-                      phi::errors::PreconditionNotMet(
-                          "The true and false block should have same rank, "
-                          "but got true_rank(%d) and false_rank(%d)",
-                          input1_dims.size(),
-                          input2_dims.size()));
     for (size_t i = 0; i < input1_dims.size(); i++) {
       if (input1_dims[i] != input2_dims[i]) {
         out_dims[i] = symbol::DimExpr{shape_analysis->GetNextSymName()};