Enable optimizer for Python 3.7 mode

DinoV · DinoV · commit 676717debcbf · 2021-01-28T11:14:38.000-08:00
Summary: This actually turns the optimizer on when we're using the Python 3.7 compiler.  We run the optimizer before doing the name binding analysis because it can end up removing functions, and we depend upon object identity to resolve scopes.

Test Plan: ./python -m test.test_compiler
diff --git a/compiler/pycodegen.py b/compiler/pycodegen.py
@@ -16,6 +16,7 @@
      CO_FUTURE_ABSIMPORT, CO_FUTURE_WITH_STATEMENT, CO_FUTURE_PRINT_FUNCTION,
      CO_COROUTINE, CO_ASYNC_GENERATOR, CO_FUTURE_BARRY_AS_BDFL, CO_FUTURE_GENERATOR_STOP,
      CO_FUTURE_ANNOTATIONS)
+from compiler.optimizer import AstOptimizer
 from compiler.unparse import to_expr
 from .visitor import ASTVisitor
 
@@ -1951,6 +1952,17 @@ def flow_graph(cls, name, filename, args=(), kwonlyargs=(), starargs=(), optimiz
 
 
 class Python37CodeGenerator(CodeGenerator):
+    @classmethod
+    def make_code_gen(cls, name, tree, filename):
+        tree = AstOptimizer().visit(tree)
+        s = symbols.SymbolVisitor()
+        walk(tree, s)
+
+        graph = cls.flow_graph(name, filename)
+        code_gen = cls(tree, s.scopes, graph = graph)
+        walk(tree, code_gen)
+        return code_gen
+
     def visitCall(self, node):
         if (node.keywords or
             not isinstance(node.func, ast.Attribute) or
diff --git a/test_compiler/test_py37.py b/test_compiler/test_py37.py
@@ -147,6 +147,13 @@ def test_compile_opt_chained_cmp_op(self):
         graph = self.to_graph('assert not a > b > c', CodeGenerator)
         self.assertInGraph(graph, 'UNARY_NOT')
 
+    def test_compile_opt_enabled(self):
+        graph = self.to_graph('x = -1', Python37CodeGenerator)
+        self.assertNotInGraph(graph, 'UNARY_NEGATIVE')
+
+        graph = self.to_graph('x = -1', CodeGenerator)
+        self.assertInGraph(graph, 'UNARY_NEGATIVE')
+
     def test_ast_optimizer(self):
         cases = [
             ("+1", "1"),
