pnnx export with ptpath (#5239)

* pnnx export with ptpath

* build and test python pnnx

.ci/pnnx.yml

@@ -127,3 +127,12 @@ jobs:
         export MKL_ENABLE_INSTRUCTIONS=SSE4_2
         cd tools/pnnx
         cd build && ctest --output-on-failure -j 16
+
+    - name: python-pnnx
+      run: |
+        export PYTHONUSERBASE=${{ci.workspace}}/torch-${{matrix.torch-version}}
+        export PNNX_WHEEL_WITHOUT_BUILD=ON
+        cd tools/pnnx
+        cp build/src/pnnx python/pnnx/
+        python3 setup.py install --user
+        pytest python/tests/

tools/pnnx/python/README.md

@@ -76,8 +76,8 @@ net = models.resnet18(pretrained=True)
 x = torch.rand(1, 3, 224, 224)
 
 # You could try disabling checking when torch tracing raises error
-# opt_net = pnnx.export(net, "resnet18", x, check_trace=False)
-opt_net = pnnx.export(net, "resnet18", x)
+# opt_net = pnnx.export(net, "resnet18.pt", x, check_trace=False)
+opt_net = pnnx.export(net, "resnet18.pt", x)
 ```
 
 2. convert existing model to pnnx
@@ -94,7 +94,7 @@ opt_net = pnnx.convert("resnet18.pt", x)
 
 `model` (torch.nn.Model): model to be exported.
 
-`filename` (str): the file name.
+`ptpath` (str): the torchscript name.
 
 `inputs` (torch.Tensor of list of torch.Tensor) expected inputs of the model.
 

tools/pnnx/python/pnnx/utils/export.py

@@ -15,7 +15,7 @@
 import torch
 import os
 
-def export(model, filename, inputs = None, inputs2 = None, input_shapes = None, input_types = None,
+def export(model, ptpath, inputs = None, inputs2 = None, input_shapes = None, input_types = None,
            input_shapes2 = None, input_types2 = None, device = None, customop = None,
            moduleop = None, optlevel = None, pnnxparam = None, pnnxbin = None,
            pnnxpy = None, pnnxonnx = None, ncnnparam = None, ncnnbin = None, ncnnpy = None,
@@ -27,8 +27,7 @@ def export(model, filename, inputs = None, inputs2 = None, input_shapes = None,
 
     model.eval()
     mod = torch.jit.trace(model, inputs, check_trace=check_trace)
-    mod.save(filename)
-    ptpath = os.path.abspath(filename)
+    mod.save(ptpath)
 
     from . import convert
     return convert(ptpath, inputs, inputs2, input_shapes, input_types, input_shapes2, input_types2, device, customop, moduleop, optlevel, pnnxparam, pnnxbin, pnnxpy, pnnxonnx, ncnnparam, ncnnbin, ncnnpy)