Refactor TO_BOOL_LIST, add unit tests

Author: reidenong

Include/internal/pycore_opcode_metadata.h

@@ -3049,6 +3049,22 @@ def f(n):
         self.assertLessEqual(count_ops(ex, "_POP_TOP"), 3)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_to_bool_list(self):
+        def f(n):
+            for i in range(n):
+                lst = [] if i != TIER2_THRESHOLD else [1]
+                if lst:
+                    return 1
+            return 0
+
+        res, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
+        self.assertEqual(res, 0)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertIn("_TO_BOOL_LIST", uops)
+        self.assertLessEqual(count_ops(ex, "_POP_TOP"), 3)
+        self.assertIn("_POP_TOP_NOP", uops)
+
     def test_to_bool_always_true(self):
         def testfunc(n):
             class A:

Include/internal/pycore_uop_ids.h

@@ -514,14 +514,15 @@ dummy_func(
             EXIT_IF(!PySlice_Check(o));
         }
 
-        macro(TO_BOOL_LIST) = _GUARD_TOS_LIST + unused/1 + unused/2 + _TO_BOOL_LIST;
+        macro(TO_BOOL_LIST) = _GUARD_TOS_LIST + unused/1 + unused/2 + _TO_BOOL_LIST + POP_TOP;
 
-        op(_TO_BOOL_LIST, (value -- res)) {
+        op(_TO_BOOL_LIST, (value -- res, v)) {
             PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
             assert(PyList_CheckExact(value_o));
             STAT_INC(TO_BOOL, hit);
             res = PyList_GET_SIZE(value_o) ? PyStackRef_True : PyStackRef_False;
-            DECREF_INPUTS();
+            v = value;
+            DEAD(value);
         }
 
         inst(TO_BOOL_NONE, (unused/1, unused/2, value -- res)) {

Include/internal/pycore_uop_metadata.h

@@ -409,11 +409,12 @@ dummy_func(void) {
         v = value;
     }
 
-    op(_TO_BOOL_LIST, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
+    op(_TO_BOOL_LIST, (value -- res, v)) {
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, true);
         if (!already_bool) {
             res = sym_new_type(ctx, &PyBool_Type);
         }
+        v = value;
     }
 
     op(_TO_BOOL_NONE, (value -- res)) {