[Torch] Clean up usage of try ... infer_value() ... except

python/tvm/relay/frontend/common.py

@@ -563,6 +563,21 @@ def infer_value_simulated(input_val, params):
     return output_value
 
 
+def try_infer_value(val, on_success, on_failure=None):
+    """Try running infer_value on the input val, and if successful, pass the inferred value to
+    on_success callback. Otherwise, run on_failure callback if it is provided or return the
+    input val as output. In each case, the second return value indicates whether infer_value has
+    succeeded or not.
+    """
+    try:
+        ret = infer_value(val, {}).asnumpy()
+        return on_success(ret), True
+    except Exception:
+        if on_failure:
+            return on_failure(), False
+        return val, False
+
+
 def new_var(name_hint, type_annotation=None, shape=None, dtype="float32"):
     return _expr.var(name_hint, type_annotation, shape, dtype)
 

python/tvm/relay/frontend/pytorch.py

@@ -16,7 +16,7 @@
 # under the License.
 # pylint: disable=import-self, too-many-lines, len-as-condition, no-else-return, unused-variable, too-many-nested-blocks
 # pylint: disable=consider-iterating-dictionary, invalid-name, unused-argument, unused-variable, broad-except
-# pylint: disable=import-outside-toplevel, simplifiable-if-expression, unnecessary-comprehension
+# pylint: disable=import-outside-toplevel, simplifiable-if-expression, cell-var-from-loop, unnecessary-lambda
 """PT: PyTorch frontend."""
 import itertools
 import logging
@@ -36,6 +36,7 @@
 from .common import AttrCvt, get_relay_op
 from .common import infer_shape as _infer_shape
 from .common import infer_value as _infer_value
+from .common import try_infer_value
 from .common import infer_value_simulated as _infer_value_simulated
 from .common import infer_type as _infer_type
 from ..prelude import Prelude, StaticTensorArrayOps
@@ -185,11 +186,8 @@ def _impl(inputs, input_types):
         def _get_value(val, dtype):
             # dtype is a tvm dtype
             if isinstance(val, _expr.Expr):
-                try:
-                    ret = _infer_value(_op.cast(val, dtype), {}).asnumpy()
-                    ret = _expr.const(ret, dtype)
-                except Exception:
-                    ret = _op.cast(val, dtype)
+                inp = _op.cast(val, dtype)
+                ret, _ = try_infer_value(inp, lambda ret: _expr.const(ret, dtype))
             else:
                 ret = _create_typed_const(val, dtype)
             return ret
@@ -305,10 +303,7 @@ def _impl(inputs, input_types):
         dim = int(inputs[1])
         stride = int(inputs[4])
         if isinstance(inputs[2], _expr.Call):
-            try:
-                begin[dim] = np.asscalar(_infer_value(inputs[2], {}).asnumpy().astype(np.int))
-            except Exception:
-                begin[dim] = inputs[2]
+            begin[dim], _ = try_infer_value(inputs[2], lambda ret: np.asscalar(ret.astype(np.int)))
         else:
             begin[dim] = int(inputs[2])
 
@@ -329,10 +324,9 @@ def _impl(inputs, input_types):
             target_end = int(inputs[3])
         else:
             if isinstance(inputs[3], _expr.Expr):
-                try:
-                    target_end = np.asscalar(_infer_value(inputs[3], {}).asnumpy().astype(np.int))
-                except Exception:
-                    target_end = inputs[3]
+                target_end, _ = try_infer_value(
+                    inputs[3], lambda ret: np.asscalar(ret.astype(np.int))
+                )
             else:
                 target_end = inputs[3]
 
@@ -457,10 +451,7 @@ def _impl(inputs, input_types):
         sort = bool(inputs[4])
 
         if isinstance(inputs[1], _expr.Expr):
-            try:
-                k = _infer_value(inputs[1], {}).asnumpy().tolist()
-            except Exception:
-                k = inputs[1]
+            k, _ = try_infer_value(inputs[1], lambda ret: ret.tolist())
         else:
             k = inputs[1]
 
@@ -546,15 +537,15 @@ def _full_impl(data, fill_value, dtype):
                     size.append(dim)
                 new_shape.append(dim)
             else:
-                try:
-                    dim = int(_infer_value(dim, {}).asnumpy())
+                dim, success = try_infer_value(dim, lambda ret: int(ret), lambda: 0)
+                new_shape.append(dim)
+
+                if success:
                     if isinstance(size, list):
                         size.append(dim)
-                    new_shape.append(dim)
-                except Exception:
+                else:
                     size = None
                     need_reshape = True
-                    new_shape.append(0)
         else:
             if isinstance(size, list):
                 size.append(dim)
@@ -1346,12 +1337,11 @@ def _impl(inputs, input_types):
             if isinstance(s, _expr.Constant):
                 tmp_shape.append(int(s.data.asnumpy()))
             elif isinstance(s, _expr.Expr):
-                try:
-                    dim = int(_infer_value(s, {}).asnumpy())
-                    tmp_shape.append(dim)
-                except Exception:
+                dim, success = try_infer_value(s, lambda ret: int(ret))
+                tmp_shape.append(dim)
+
+                if not success:
                     is_dyn = True
-                    tmp_shape.append(s)
             else:
                 tmp_shape.append(s)
 
@@ -2312,13 +2302,15 @@ def _impl(inputs, input_types):
         if isinstance(inputs[1], _expr.Expr):
             out_size = inputs[1]
         elif isinstance(inputs[1], list):
-            try:
-                infer_res = [_infer_value(size, {}) for size in inputs[1]]
-                out_size = [np.asscalar(res.asnumpy().astype(np.int)) for res in infer_res]
-            except Exception:
-                h = _op.expand_dims(inputs[1][0], axis=0)
-                w = _op.expand_dims(inputs[1][1], axis=0)
-                out_size = _op.concatenate([h, w], axis=0)
+            out_size = []
+            for i in [0, 1]:
+                size, _ = try_infer_value(
+                    inputs[1][i],
+                    lambda ret: ret.astype(np.int),
+                    lambda: _op.expand_dims(inputs[1][i], axis=0),
+                )
+                out_size.append(size)
+            out_size = _op.concatenate(out_size, axis=0)
 
         data = inputs[0]
         align_corners = inputs[4]