gh-131798: JIT: Narrow the return type of _GET_LEN to int

Signed-off-by: Manjusaka <me@manjusaka.me>

Author: Zheaoli

Lib/test/test_capi/test_opt.py

@@ -1923,6 +1923,19 @@ def testfunc(n):
         self.assertNotIn("_GUARD_TOS_INT", uops)
         self.assertIn("_CALL_LEN", uops)
 
+    def test_get_len(self):
+        def testfunc(n):
+            a = [1, 2, 3, 4]
+            for _ in range(n):
+                match a:
+                    case [1,2]:
+                        _ = len(a) - 1
+        _, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+        uops = get_opnames(ex)
+        self.assertNotIn("_GUARD_NOS_INT", uops)
+        self.assertNotIn("_GUARD_TOS_INT", uops)
+        self.assertIn("_GET_LEN", uops)
+
     def test_binary_op_subscr_tuple_int(self):
         def testfunc(n):
             x = 0

Python/optimizer_bytecodes.c

@@ -480,7 +480,7 @@ dummy_func(void) {
             res = sym_new_const(ctx, tmp);
             Py_DECREF(tmp);
         }
-        else {
+    else {
             res = sym_new_type(ctx, &PyBool_Type);
         }
     }
@@ -1088,6 +1088,10 @@ dummy_func(void) {
         res = sym_new_type(ctx, &PyLong_Type);
     }
 
+    op(_GET_LEN, (-- len)) {
+        len = sym_new_type(ctx, &PyLong_Type);
+    }
+
 // END BYTECODES //
 
 }