pnnx fix fused tensor_split operator insert order (#4006)

tools/pnnx/src/pass_level5/fuse_slice_to_tensor_split.cpp

@@ -57,6 +57,8 @@ void fuse_slice_to_tensor_split(Graph& graph)
             tensor_split_indices.push_back(end);
             slice_n_ops.push_back(op);
 
+            Operator* cur = op;
+
             bool full_dimsize_slice = false;
             while (1)
             {
@@ -96,6 +98,9 @@ void fuse_slice_to_tensor_split(Graph& graph)
                 if (!op2)
                     break;
 
+                if (std::find(graph.ops.begin(), graph.ops.end(), op2) < std::find(graph.ops.begin(), graph.ops.end(), cur))
+                    cur = op2;
+
                 int end2 = op2->params.at("ends").ai[0];
                 if (end2 == -1)
                 {
@@ -116,7 +121,7 @@ void fuse_slice_to_tensor_split(Graph& graph)
             matched = true;
 
             // delete all slice ops and replace with tensor_split
-            Operator* op_tensor_split = graph.new_operator_before("torch.tensor_split", op->name, op);
+            Operator* op_tensor_split = graph.new_operator_before("torch.tensor_split", op->name, cur);
             op_tensor_split->params["dim"] = dim;
             op_tensor_split->params["indices"] = tensor_split_indices;
 

tools/pnnx/tests/test_pnnx_fuse_select_to_unbind.py

@@ -24,15 +24,18 @@ class Model(nn.Module):
         x0 = torch.select(x, 0, 0)
         x1 = torch.select(x, 0, 1)
         x2 = torch.select(x, 0, 2)
+
+        z4 = torch.select(x, 2, 4)
+        z3 = torch.select(x, 2, 3)
+
         y0 = torch.select(x, 1, 0)
         y1 = torch.select(x, 1, 1)
         y2 = torch.select(x, 1, 2)
         y3 = torch.select(x, 1, 3)
-        z0 = torch.select(x, 2, 0)
-        z1 = torch.select(x, 2, 1)
+
         z2 = torch.select(x, 2, 2)
-        z3 = torch.select(x, 2, 3)
-        z4 = torch.select(x, 2, 4)
+        z1 = torch.select(x, 2, 1)
+        z0 = torch.select(x, 2, 0)
 
         return x0, x1, x2, y0, y1, y2, y3, z0, z1, z2, z3, z4
 

tools/pnnx/tests/test_pnnx_fuse_slice_to_tensor_split.py

@@ -24,14 +24,15 @@ class Model(nn.Module):
         x0 = x[:3]
         x1 = x[3:]
 
+        z3 = z[:,:,7:]
+        z2 = z[:,:,4:7]
+
         y0 = y[:2,:]
         y1 = y[2:4,:]
         y2 = y[4:,:]
 
-        z0 = z[:,:,:2]
         z1 = z[:,:,2:4]
-        z2 = z[:,:,4:7]
-        z3 = z[:,:,7:]
+        z0 = z[:,:,:2]
 
         return x0, x1, y0, y1, y2, z0, z1, z2, z3