Merge branch 'main' into hack-night2

python · brandtbucher · Mar 4, 2025 · Feb 22, 2025 · Feb 22, 2025 · Feb 22, 2025
commit 905d3efcfeb424eb2dd75653f4c9275912774386
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
@@ -1499,7 +1499,39 @@ def f(n):
         # But all of the appends we care about are still there:
         self.assertEqual(uops.count("_CALL_LIST_APPEND"), len("ABCDEFG"))
 
-    def test_narrow_type_to_constant_str_empty(self):
+    def test_narrow_type_to_constant_int_zero(self):
+        def f(n):
+            trace = []
+            for i in range(n):
+                # zero is always (int) 0, but we can only prove that it's a integer:
+                false = i == TIER2_THRESHOLD # this will always be false, while hopefully still fooling optimizer improvements
+                zero = false + 0 # this should always set the variable zero equal to 0
+                trace.append("A")
+                if not zero:  # Kept.
+                    trace.append("B")
+                    if not zero:  # Removed!
+                        trace.append("C")
+                    trace.append("D")
+                    if zero:  # Removed!
+                        trace.append("X")
+                    trace.append("E")
+                trace.append("F")
+                if zero:  # Removed!
+                    trace.append("X")
+                trace.append("G")
+            return trace
+
+        trace, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
+        self.assertEqual(trace, list("ABCDEFG") * TIER2_THRESHOLD)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        # Only one guard remains:
+        self.assertEqual(uops.count("_GUARD_IS_FALSE_POP"), 1)
+        self.assertEqual(uops.count("_GUARD_IS_TRUE_POP"), 0)
+        # But all of the appends we care about are still there:
+        self.assertEqual(uops.count("_CALL_LIST_APPEND"), len("ABCDEFG"))
+
+def test_narrow_type_to_constant_str_empty(self):
         def f(n):
             trace = []
             for i in range(n):
@@ -1532,7 +1564,6 @@ def f(n):
         # But all of the appends we care about are still there:
         self.assertEqual(uops.count("_CALL_LIST_APPEND"), len("ABCDEFG"))
 
-
 def global_identity(x):
     return x
 

@@ -299,6 +299,9 @@ _Py_uop_sym_set_const(JitOptContext *ctx, JitOptSymbol *sym, PyObject *const_val
             else if (type == &PyBool_Type) {
                 _Py_uop_sym_set_const(ctx, value, Py_False);
             }
+            else if (type == &PyLong_Type) {
+                _Py_uop_sym_set_const(ctx, value, Py_GetConstant(Py_CONSTANT_ZERO));
+            }
             else if (type == &PyUnicode_Type) {
                 _Py_uop_sym_set_const(ctx, value, Py_GetConstant(Py_CONSTANT_EMPTY_STR));
             }