[Python-checkins] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/7cd581a6bf82309b3c9b9251c54067d442732485
commit: 7cd581a6bf82309b3c9b9251c54067d442732485
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-06-13T23:13:24-07:00
summary:

bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071)


Fix a regression introduced by af8646c8054d0f4180a2013383039b6a472f9698 that was causing code of the form:

if True and False:
   do_something()

to be optimized incorrectly, eliminating the block.
(cherry picked from commit 05f831865545b08c9a21cfb7773af58b76ec64cb)

Co-authored-by: Pablo Galindo <Pablogsal at gmail.com>

files:
A Misc/NEWS.d/next/Core and Builtins/2019-06-14-06-32-33.bpo-37269.SjVVAe.rst
M Lib/test/test_peepholer.py
M Python/peephole.c

diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 860ceeb003e7..5d00240e2595 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -414,6 +414,13 @@ def forloop():
                 pass
         self.assertEqual(count_instr_recursively(forloop, 'BUILD_LIST'), 0)
 
+    def test_condition_with_binop_with_bools(self):
+        def f():
+            if True or False:
+                return 1
+            return 0
+        self.assertEqual(f(), 1)
+
 
 class TestBuglets(unittest.TestCase):
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-06-14-06-32-33.bpo-37269.SjVVAe.rst b/Misc/NEWS.d/next/Core and Builtins/2019-06-14-06-32-33.bpo-37269.SjVVAe.rst
new file mode 100644
index 000000000000..b9b79066774f
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-06-14-06-32-33.bpo-37269.SjVVAe.rst	
@@ -0,0 +1,2 @@
+Fix a bug in the peephole optimizer that was not treating correctly constant
+conditions with binary operators. Patch by Pablo Galindo.
diff --git a/Python/peephole.c b/Python/peephole.c
index 6f3e2ed88b2b..d7b1dfc4d9c1 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -315,6 +315,11 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
                     fill_nops(codestr, op_start, nexti + 1);
                     cumlc = 0;
                 } else if (is_true == 0) {
+                    if (i > 1 &&
+                        (_Py_OPCODE(codestr[i - 1]) == POP_JUMP_IF_TRUE ||
+                         _Py_OPCODE(codestr[i - 1]) == POP_JUMP_IF_FALSE)) {
+                        break;
+                    }
                     h = get_arg(codestr, nexti) / sizeof(_Py_CODEUNIT);
                     tgt = find_op(codestr, codelen, h);
                     fill_nops(codestr, op_start, tgt);