pythongh-109627: duplicated smalll exit blocks need to be assigned ju…

…mp target labels

Lib/test/test_compile.py

@@ -1252,6 +1252,15 @@ def f():
             return a, b
         self.assertEqual(f(), (54, 96))
 
+    def test_duplicated_exit_block_which_is_jump_target(self):
+        # See gh-109627
+        def f():
+            while element and something:
+                try:
+                    return something
+                except:
+                    pass
+
 
 @requires_debug_ranges()
 class TestSourcePositions(unittest.TestCase):

Python/flowgraph.c

@@ -2229,6 +2229,19 @@ is_exit_without_lineno(basicblock *b) {
     return true;
 }
 
+
+static int
+max_label(cfg_builder *g)
+{
+    int lbl = -1;
+    for (basicblock *b = g->g_entryblock; b != NULL; b = b->b_next) {
+        if (b->b_label.id > lbl) {
+            lbl = b->b_label.id;
+        }
+    }
+    return lbl;
+}
+
 /* PEP 626 mandates that the f_lineno of a frame is correct
  * after a frame terminates. It would be prohibitively expensive
  * to continuously update the f_lineno field at runtime,
@@ -2242,6 +2255,9 @@ static int
 duplicate_exits_without_lineno(cfg_builder *g)
 {
     assert(no_empty_basic_blocks(g));
+
+    int next_lbl = max_label(g) + 1;
+
     /* Copy all exit blocks without line number that are targets of a jump.
      */
     basicblock *entryblock = g->g_entryblock;
@@ -2260,6 +2276,7 @@ duplicate_exits_without_lineno(cfg_builder *g)
                 target->b_predecessors--;
                 new_target->b_predecessors = 1;
                 new_target->b_next = target->b_next;
+                new_target->b_label.id = next_lbl++;
                 target->b_next = new_target;
             }
         }