[Relax][PyTorch] Support linspace op for ExportedProgram importer (#17889)

* Update base_fx_graph_translator.py

* Update exported_program_translator.py

* Update test_frontend_from_exported_program.py

* Update test_frontend_from_exported_program.py

* Update test_frontend_from_exported_program.py

* fix lint

* Update test_frontend_from_exported_program.py

Author: tlopex

python/tvm/relax/frontend/torch/base_fx_graph_translator.py

@@ -1465,6 +1465,29 @@ def _inplace_masked_fill(self, node: fx.Node) -> relax.Var:
         self.env[node.args[0]] = output
         return output
 
+    def _linspace(self, node: fx.Node) -> relax.Var:
+        args = self.retrieve_args(node)
+        start = args[0]
+        stop = args[1]
+        step = args[2]
+
+        if step != 1:
+            step = (stop - start) / (step - 1)
+            stop = stop + (step / 2)
+        else:
+            stop = start + step
+
+        if len(args) <= 3 or args[3] is None:
+            import torch
+
+            dtype = self._convert_data_type(str(torch.get_default_dtype()))
+        else:
+            dtype = self._convert_data_type(args[3])
+
+        return self.block_builder.emit(
+            relax.op.arange(start=start, end=stop, step=step, dtype=dtype)
+        )
+
     def _masked_fill(self, node: fx.Node) -> relax.Var:
         x = self.env[node.args[0]]
         mask = self.env[node.args[1]]

python/tvm/relax/frontend/torch/exported_program_translator.py

@@ -475,6 +475,7 @@ def create_convert_map(
             "full_like.default": self._full_like,
             "index_select.default": self._index_select,
             "lift_fresh_copy.default": self._to_copy,
+            "linspace.default": self._linspace,
             "masked_fill.Scalar": self._masked_fill,
             "new_ones.default": self._new_ones,
             "one_hot.default": self._one_hot,

tests/python/relax/test_frontend_from_exported_program.py

@@ -4817,5 +4817,26 @@ def main(
     verify_model(Eye2(), example_args2, {}, Expected2)
 
 
+def test_linspace():
+    class Linspace(Module):
+        def forward(self, input):
+            return torch.linspace(0, 1, steps=9, dtype=torch.float32)
+
+    @tvm.script.ir_module
+    class Expected:
+        @R.function
+        def main(
+            input: R.Tensor((9, 9), dtype="float32")
+        ) -> R.Tuple(R.Tensor((9,), dtype="float32")):
+            with R.dataflow():
+                lv: R.Tensor((9,), dtype="float32") = R.arange(0, 1.0625, 0.125, dtype="float32")
+                gv: R.Tuple(R.Tensor((9,), dtype="float32")) = (lv,)
+                R.output(gv)
+            return gv
+
+    example_args = (torch.randn(9, 9, dtype=torch.float32),)
+    verify_model(Linspace(), example_args, {}, Expected)
+
+
 if __name__ == "__main__":
     tvm.testing.main()