gh-115480: Type propagate _BINARY_OP_ADD_UNICODE (GH-115710)

Author: Fidget-Spinner

Lib/test/test_capi/test_opt.py

@@ -795,11 +795,14 @@ def test_float_add_constant_propagation(self):
         def testfunc(n):
             a = 1.0
             for _ in range(n):
-                a = a + 0.1
+                a = a + 0.25
+                a = a + 0.25
+                a = a + 0.25
+                a = a + 0.25
             return a
 
         res, ex = self._run_with_optimizer(testfunc, 32)
-        self.assertAlmostEqual(res, 4.2)
+        self.assertAlmostEqual(res, 33.0)
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
         guard_both_float_count = [opname for opname in iter_opnames(ex) if opname == "_GUARD_BOTH_FLOAT"]
@@ -812,11 +815,14 @@ def test_float_subtract_constant_propagation(self):
         def testfunc(n):
             a = 1.0
             for _ in range(n):
-                a = a - 0.1
+                a = a - 0.25
+                a = a - 0.25
+                a = a - 0.25
+                a = a - 0.25
             return a
 
         res, ex = self._run_with_optimizer(testfunc, 32)
-        self.assertAlmostEqual(res, -2.2)
+        self.assertAlmostEqual(res, -31.0)
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
         guard_both_float_count = [opname for opname in iter_opnames(ex) if opname == "_GUARD_BOTH_FLOAT"]
@@ -829,11 +835,14 @@ def test_float_multiply_constant_propagation(self):
         def testfunc(n):
             a = 1.0
             for _ in range(n):
-                a = a * 2.0
+                a = a * 1.0
+                a = a * 1.0
+                a = a * 1.0
+                a = a * 1.0
             return a
 
         res, ex = self._run_with_optimizer(testfunc, 32)
-        self.assertAlmostEqual(res, 2 ** 32)
+        self.assertAlmostEqual(res, 1.0)
         self.assertIsNotNone(ex)
         uops = get_opnames(ex)
         guard_both_float_count = [opname for opname in iter_opnames(ex) if opname == "_GUARD_BOTH_FLOAT"]
@@ -842,6 +851,24 @@ def testfunc(n):
         # We'll also need to verify that propagation actually occurs.
         self.assertIn("_BINARY_OP_MULTIPLY_FLOAT", uops)
 
+    def test_add_unicode_propagation(self):
+        def testfunc(n):
+            a = ""
+            for _ in range(n):
+                a + a
+                a + a
+                a + a
+                a + a
+            return a
+
+        res, ex = self._run_with_optimizer(testfunc, 32)
+        self.assertEqual(res, "")
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        guard_both_unicode_count = [opname for opname in iter_opnames(ex) if opname == "_GUARD_BOTH_UNICODE"]
+        self.assertLessEqual(len(guard_both_unicode_count), 1)
+        self.assertIn("_BINARY_OP_ADD_UNICODE", uops)
+
     def test_compare_op_type_propagation_float(self):
         def testfunc(n):
             a = 1.0

Python/optimizer_bytecodes.c

@@ -254,6 +254,22 @@ dummy_func(void) {
         }
     }
 
+    op(_BINARY_OP_ADD_UNICODE, (left, right -- res)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyUnicode_Type) && sym_matches_type(right, &PyUnicode_Type)) {
+            PyObject *temp = PyUnicode_Concat(sym_get_const(left), sym_get_const(right));
+            if (temp == NULL) {
+                goto error;
+            }
+            res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
+        }
+        else {
+            OUT_OF_SPACE_IF_NULL(res = sym_new_type(ctx, &PyUnicode_Type));
+        }
+    }
+
     op(_TO_BOOL, (value -- res)) {
         (void)value;
         res = sym_new_type(ctx, &PyBool_Type);