GH-130415: Optimize constant comparison in JIT builds

Lib/test/test_capi/test_opt.py

@@ -1531,7 +1531,7 @@ 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_str_empty(self):
  def f(n):
  trace = []
  for i in range(n):
@@ -1564,6 +1564,23 @@ 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_compare_pop_two_load_const_inline_borrow(self):
+ def testfunc(n):
+ x = 0
+ for _ in range(n):
+ a = 10
+ b = 10
+ if a == b:
+ x += 1
+ return x
+
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(res, TIER2_THRESHOLD)
+ self.assertIsNotNone(ex)
+ uops = get_opnames(ex)
+ self.assertNotIn("_COMPARE_OP_INT", uops)
+ self.assertIn("_POP_TWO_LOAD_CONST_INLINE_BORROW", uops)
+
 def global_identity(x):
  return x
 

Misc/NEWS.d/next/Core_and_Builtins/2025-03-20-03-45-20.gh-issue-130415.VtJhoG.rst

@@ -0,0 +1 @@
+Optimize comparison of two constants in JIT builds

Python/bytecodes.c

@@ -5133,6 +5133,12 @@ dummy_func(
  value = PyStackRef_FromPyObjectImmortal(ptr);
  }
 
+ tier2 pure op(_POP_TWO_LOAD_CONST_INLINE_BORROW, (ptr/4, pop1, pop2 -- value)) {
+ PyStackRef_CLOSE(pop2);
+ PyStackRef_CLOSE(pop1);
+ value = PyStackRef_FromPyObjectImmortal(ptr);
+ }
+
  tier2 op(_CHECK_FUNCTION, (func_version/2 -- )) {
  assert(PyStackRef_FunctionCheck(frame->f_funcobj));
  PyFunctionObject *func = (PyFunctionObject *)PyStackRef_AsPyObjectBorrow(frame->f_funcobj);

Python/optimizer_bytecodes.c

@@ -446,7 +446,25 @@ dummy_func(void) {
  }
 
  op(_COMPARE_OP_INT, (left, right -- res)) {
- res = sym_new_type(ctx, &PyBool_Type);
+ if (sym_is_const(ctx, left) && sym_is_const(ctx, right))
+ {
+ assert(PyLong_CheckExact(sym_get_const(ctx, left)));
+ assert(PyLong_CheckExact(sym_get_const(ctx, right)));
+ PyObject *tmp = PyObject_RichCompare(sym_get_const(ctx, left),
+ sym_get_const(ctx, right),
+ oparg >> 5);
+ if (tmp == NULL) {
+ goto error;
+ }
+ assert(PyBool_Check(tmp));
+ assert(_Py_IsImmortal(tmp));
+ REPLACE_OP(this_instr, _POP_TWO_LOAD_CONST_INLINE_BORROW, 0, (uintptr_t)tmp);
+ res = sym_new_const(ctx, tmp);
+ Py_DECREF(tmp);
+ }
+ else {
+ res = sym_new_type(ctx, &PyBool_Type);
+ }
  }
 
  op(_COMPARE_OP_FLOAT, (left, right -- res)) {