Match 3.7's try/except code generation

DinoV · DinoV · commit df1701413c07 · 2021-01-28T11:14:38.000-08:00
Summary: Python 3.7 made some minor changes to it's generation of the except blocks by moving where the POP_EXCEPT occurs.  This just overrides the behavior in the 3.7 compiler to match.

Test Plan: ./python -m test.test_compiler
diff --git a/compiler/pycodegen.py b/compiler/pycodegen.py
@@ -2091,6 +2091,26 @@ def visitAsyncWith(self, node):
 
         return super().visitAsyncWith(node)
 
+    def visitTryFinally(self, node, except_protect=False):
+        body = self.newBlock()
+        final = self.newBlock()
+        self.emit('SETUP_FINALLY', final)
+        self.nextBlock(body)
+        self.setups.push((TRY_FINALLY, body))
+        if node.handlers:
+            self.visitTryExcept(node)
+        else:
+            self.visit(node.body)
+        self.emit('POP_BLOCK')
+        self.setups.pop()
+        self.emit('LOAD_CONST', None)
+        self.nextBlock(final)
+        self.setups.push((END_FINALLY, final))
+        self.visit(node.finalbody)
+        self.emit('END_FINALLY')
+        if except_protect:
+            self.emit('POP_EXCEPT')
+        self.setups.pop()
 
 def get_default_generator():
     if sys.version_info >= (3, 7):
diff --git a/test_compiler/test_py37.py b/test_compiler/test_py37.py
@@ -84,6 +84,22 @@ async def f():
                             saw_aiter = True
                     break
 
+    def test_try_except_pop_except(self):
+        """POP_EXCEPT moved after END_FINALLY in Python 3.7"""
+        for generator in (Python37CodeGenerator, CodeGenerator):
+            graph = self.to_graph("""
+                try:
+                    pass
+                except Exception as e:
+                    pass
+            """, generator)
+            prev_instr = None
+            for instr in self.graph_to_instrs(graph):
+                if instr.opname == "POP_EXCEPT":
+                    self.assertEqual(prev_instr.opname == "END_FINALLY", generator is Python37CodeGenerator, prev_instr.opname)
+                prev_instr = instr
+
+
     def test_future_annotations(self):
         annotations = ["42"]
         for annotation in annotations:
