gh-115859: Disable the tier 2 redundancy eliminator by default (GH-115860)

Author: Fidget-Spinner

Lib/test/test_capi/test_opt.py

@@ -4,6 +4,7 @@
 import textwrap
 import unittest
 import gc
+import os
 
 import _testinternalcapi
 
@@ -568,6 +569,8 @@ def testfunc(n):
         count = ops.count("_GUARD_IS_TRUE_POP") + ops.count("_GUARD_IS_FALSE_POP")
         self.assertLessEqual(count, 2)
 
+
+@unittest.skipIf(os.getenv("PYTHONUOPSOPTIMIZE", default=0) == 0, "Needs uop optimizer to run.")
 class TestUopsOptimization(unittest.TestCase):
 
     def _run_with_optimizer(self, testfunc, arg):

Python/optimizer_analysis.c

@@ -810,9 +810,12 @@ _Py_uop_analyze_and_optimize(
 
     peephole_opt(frame, buffer, buffer_size);
 
-    err = uop_redundancy_eliminator(
-        (PyCodeObject *)frame->f_executable, buffer,
-        buffer_size, curr_stacklen, dependencies);
+    char *uop_optimize = Py_GETENV("PYTHONUOPSOPTIMIZE");
+    if (uop_optimize != NULL && *uop_optimize > '0') {
+        err = uop_redundancy_eliminator(
+            (PyCodeObject *)frame->f_executable, buffer,
+            buffer_size, curr_stacklen, dependencies);
+    }
 
     if (err == 0) {
         goto not_ready;