Add dynamo support for operator.abs (pytorch#117442)

A test case for operator.abs and allows for constant folding with it. Partially applies to pytorch#116396

Pull Request resolved: pytorch#117442
Approved by: https://github.com/jansel, https://github.com/malfet

Author: Skylion007

test/dynamo/test_functions.py

@@ -2136,6 +2136,17 @@ def fn(x):
                 x = torch.randn(10)
                 self.assertEqual(opt_fn(x), fn(x))
 
+    def test_unary_fold_op(self):
+        for op in (operator.abs, abs, operator.pos, operator.neg):
+            with self.subTest(op=op):
+
+                def fn():
+                    a = range(-10, 10)
+                    return list(map(op, a))
+
+                opt_fn = torch._dynamo.optimize(nopython=True)(fn)
+                self.assertEqual(opt_fn(), fn())
+
 
 instantiate_parametrized_tests(FunctionTests)
 

torch/_dynamo/variables/builtin.py

@@ -112,6 +112,7 @@ def _constant_fold_functions():
             str.format,
             sum,
             type,
+            operator.abs,
             operator.pos,
             operator.neg,
             operator.not_,
@@ -155,6 +156,7 @@ def can_constant_fold_through(self):
     @functools.lru_cache(None)
     def _fx_graph_functions():
         fns = {
+            operator.abs,
             operator.pos,
             operator.neg,
             operator.not_,