[Python-checkins] [3.7] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071) (GH-14073)

[Pablo Galindo]

https://github.com/python/cpython/commit/5292179afc6fd0dc533add054d4790773c9766d0
commit: 5292179afc6fd0dc533add054d4790773c9766d0
branch: 3.7
author: Pablo Galindo <Pablogsal at gmail.com>
committer: GitHub <noreply at github.com>
date: 2019-06-14T07:18:51+01:00
summary:

[3.7] bpo-37269: Correctly optimise conditionals with constant booleans (GH-14071) (GH-14073)

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 0cc1e92907b5..1a031544fc01 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -311,6 +311,13 @@ def test_constant_folding(self):
                 self.assertFalse(instr.opname.startswith('BINARY_'))
                 self.assertFalse(instr.opname.startswith('BUILD_'))
 
+    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 1ae62fa39a27..f1b71ed1a730 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -313,6 +313,11 @@ 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);