[Python-checkins] cpython: Closes #11471: avoid generating a JUMP_FORWARD instruction at the end of an

antoine.pitrou python-checkins at python.org
Thu Sep 18 03:06:56 CEST 2014


http://hg.python.org/cpython/rev/c0ca9d32aed4
changeset:   92460:c0ca9d32aed4
user:        Antoine Pitrou <solipsis at pitrou.net>
date:        Thu Sep 18 03:06:50 2014 +0200
summary:
  Closes #11471: avoid generating a JUMP_FORWARD instruction at the end of an if-block if there is no else-clause.

Original patch by Eugene Toder.

files:
  Lib/test/test_dis.py |  172 +++++++++++++++---------------
  Misc/NEWS            |    3 +
  Python/compile.c     |    6 +-
  3 files changed, 90 insertions(+), 91 deletions(-)


diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -568,10 +568,10 @@
 #_instructions = dis.get_instructions(outer, first_line=expected_outer_line)
 #print('expected_opinfo_outer = [\n  ',
       #',\n  '.join(map(str, _instructions)), ',\n]', sep='')
-#_instructions = dis.get_instructions(outer(), first_line=expected_outer_line)
+#_instructions = dis.get_instructions(outer(), first_line=expected_f_line)
 #print('expected_opinfo_f = [\n  ',
       #',\n  '.join(map(str, _instructions)), ',\n]', sep='')
-#_instructions = dis.get_instructions(outer()(), first_line=expected_outer_line)
+#_instructions = dis.get_instructions(outer()(), first_line=expected_inner_line)
 #print('expected_opinfo_inner = [\n  ',
       #',\n  '.join(map(str, _instructions)), ',\n]', sep='')
 #_instructions = dis.get_instructions(jumpy, first_line=expected_jumpy_line)
@@ -642,12 +642,12 @@
 ]
 
 expected_opinfo_jumpy = [
-  Instruction(opname='SETUP_LOOP', opcode=120, arg=74, argval=77, argrepr='to 77', offset=0, starts_line=3, is_jump_target=False),
+  Instruction(opname='SETUP_LOOP', opcode=120, arg=68, argval=71, argrepr='to 71', offset=0, starts_line=3, is_jump_target=False),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=0, argval='range', argrepr='range', offset=3, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=1, argval=10, argrepr='10', offset=6, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=9, starts_line=None, is_jump_target=False),
   Instruction(opname='GET_ITER', opcode=68, arg=None, argval=None, argrepr='', offset=12, starts_line=None, is_jump_target=False),
-  Instruction(opname='FOR_ITER', opcode=93, arg=50, argval=66, argrepr='to 66', offset=13, starts_line=None, is_jump_target=True),
+  Instruction(opname='FOR_ITER', opcode=93, arg=44, argval=60, argrepr='to 60', offset=13, starts_line=None, is_jump_target=True),
   Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=16, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=19, starts_line=4, is_jump_target=False),
   Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=22, starts_line=None, is_jump_target=False),
@@ -656,92 +656,88 @@
   Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=29, starts_line=5, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=32, starts_line=None, is_jump_target=False),
   Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=35, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=47, argval=47, argrepr='', offset=38, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=44, argval=44, argrepr='', offset=38, starts_line=None, is_jump_target=False),
   Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=41, starts_line=6, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=0, argval=47, argrepr='to 47', offset=44, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=47, starts_line=7, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=50, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=53, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=13, argval=13, argrepr='', offset=56, starts_line=None, is_jump_target=False),
-  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=59, starts_line=8, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=60, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=63, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=66, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=67, starts_line=10, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=70, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=73, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=76, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_LOOP', opcode=120, arg=74, argval=154, argrepr='to 154', offset=77, starts_line=11, is_jump_target=True),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=80, starts_line=None, is_jump_target=True),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=143, argval=143, argrepr='', offset=83, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=86, starts_line=12, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=89, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=92, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=95, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=96, starts_line=13, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=99, starts_line=None, is_jump_target=False),
-  Instruction(opname='INPLACE_SUBTRACT', opcode=56, arg=None, argval=None, argrepr='', offset=102, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=103, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=106, starts_line=14, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=109, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=112, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=124, argval=124, argrepr='', offset=115, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=80, argval=80, argrepr='', offset=118, starts_line=15, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=0, argval=124, argrepr='to 124', offset=121, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=124, starts_line=16, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=127, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=130, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=80, argval=80, argrepr='', offset=133, starts_line=None, is_jump_target=False),
-  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=136, starts_line=17, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=80, argval=80, argrepr='', offset=137, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=80, argval=80, argrepr='', offset=140, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=143, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=144, starts_line=19, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=147, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=150, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=153, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=72, argval=229, argrepr='to 229', offset=154, starts_line=20, is_jump_target=True),
-  Instruction(opname='SETUP_EXCEPT', opcode=121, arg=12, argval=172, argrepr='to 172', offset=157, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=160, starts_line=21, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=163, starts_line=None, is_jump_target=False),
-  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=167, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=168, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=28, argval=200, argrepr='to 200', offset=169, starts_line=None, is_jump_target=False),
-  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=172, starts_line=22, is_jump_target=True),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=173, starts_line=None, is_jump_target=False),
-  Instruction(opname='COMPARE_OP', opcode=107, arg=10, argval='exception match', argrepr='exception match', offset=176, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=199, argval=199, argrepr='', offset=179, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=44, starts_line=7, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=47, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=50, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=13, argval=13, argrepr='', offset=53, starts_line=None, is_jump_target=False),
+  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=56, starts_line=8, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=13, argval=13, argrepr='', offset=57, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=60, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=61, starts_line=10, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=4, argval='I can haz else clause?', argrepr="'I can haz else clause?'", offset=64, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=67, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=70, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_LOOP', opcode=120, arg=68, argval=142, argrepr='to 142', offset=71, starts_line=11, is_jump_target=True),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=74, starts_line=None, is_jump_target=True),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=131, argval=131, argrepr='', offset=77, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=80, starts_line=12, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=83, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=86, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=89, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=90, starts_line=13, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=93, starts_line=None, is_jump_target=False),
+  Instruction(opname='INPLACE_SUBTRACT', opcode=56, arg=None, argval=None, argrepr='', offset=96, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=0, argval='i', argrepr='i', offset=97, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=100, starts_line=14, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=3, argval=6, argrepr='6', offset=103, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=4, argval='>', argrepr='>', offset=106, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=115, argval=115, argrepr='', offset=109, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=74, argval=74, argrepr='', offset=112, starts_line=15, is_jump_target=False),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=115, starts_line=16, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=2, argval=4, argrepr='4', offset=118, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=0, argval='<', argrepr='<', offset=121, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=74, argval=74, argrepr='', offset=124, starts_line=None, is_jump_target=False),
+  Instruction(opname='BREAK_LOOP', opcode=80, arg=None, argval=None, argrepr='', offset=127, starts_line=17, is_jump_target=False),
+  Instruction(opname='JUMP_ABSOLUTE', opcode=113, arg=74, argval=74, argrepr='', offset=128, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=131, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=132, starts_line=19, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=6, argval='Who let lolcatz into this test suite?', argrepr="'Who let lolcatz into this test suite?'", offset=135, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=138, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=141, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_FINALLY', opcode=122, arg=72, argval=217, argrepr='to 217', offset=142, starts_line=20, is_jump_target=True),
+  Instruction(opname='SETUP_EXCEPT', opcode=121, arg=12, argval=160, argrepr='to 160', offset=145, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=148, starts_line=21, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=151, starts_line=None, is_jump_target=False),
+  Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=154, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=155, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=156, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=28, argval=188, argrepr='to 188', offset=157, starts_line=None, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=160, starts_line=22, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=161, starts_line=None, is_jump_target=False),
+  Instruction(opname='COMPARE_OP', opcode=107, arg=10, argval='exception match', argrepr='exception match', offset=164, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_JUMP_IF_FALSE', opcode=114, arg=187, argval=187, argrepr='', offset=167, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=171, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=173, starts_line=23, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=176, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=179, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=182, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=183, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=184, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=185, starts_line=23, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=188, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=191, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=194, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=195, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=26, argval=225, argrepr='to 225', offset=196, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=199, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=200, starts_line=25, is_jump_target=True),
-  Instruction(opname='SETUP_WITH', opcode=143, arg=17, argval=223, argrepr='to 223', offset=203, starts_line=None, is_jump_target=False),
-  Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=206, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=209, starts_line=26, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=212, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=215, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=218, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=219, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=220, starts_line=None, is_jump_target=False),
-  Instruction(opname='WITH_CLEANUP', opcode=81, arg=None, argval=None, argrepr='', offset=223, starts_line=None, is_jump_target=True),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=224, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=225, starts_line=None, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=226, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=229, starts_line=28, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=232, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=235, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=238, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=239, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=240, starts_line=None, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=243, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=183, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=26, argval=213, argrepr='to 213', offset=184, starts_line=None, is_jump_target=False),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=187, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=188, starts_line=25, is_jump_target=True),
+  Instruction(opname='SETUP_WITH', opcode=143, arg=17, argval=211, argrepr='to 211', offset=191, starts_line=None, is_jump_target=False),
+  Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=194, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=197, starts_line=26, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=200, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=203, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=206, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=207, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=208, starts_line=None, is_jump_target=False),
+  Instruction(opname='WITH_CLEANUP', opcode=81, arg=None, argval=None, argrepr='', offset=211, starts_line=None, is_jump_target=True),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=212, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=213, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=214, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=217, starts_line=28, is_jump_target=True),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=220, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='1 positional, 0 keyword pair', offset=223, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=226, starts_line=None, is_jump_target=False),
+  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=227, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=228, starts_line=None, is_jump_target=False),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=231, starts_line=None, is_jump_target=False),
 ]
 
 # One last piece of inspect fodder to check the default line number handling
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #11471: avoid generating a JUMP_FORWARD instruction at the end of
+  an if-block if there is no else-clause.  Original patch by Eugene Toder.
+
 - Issue #22215: Now ValueError is raised instead of TypeError when str or bytes
   argument contains not permitted null character or byte.
 
diff --git a/Python/compile.c b/Python/compile.c
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -1940,7 +1940,7 @@
     } else if (constant == 1) {
         VISIT_SEQ(c, stmt, s->v.If.body);
     } else {
-        if (s->v.If.orelse) {
+        if (asdl_seq_LEN(s->v.If.orelse)) {
             next = compiler_new_block(c);
             if (next == NULL)
                 return 0;
@@ -1950,8 +1950,8 @@
         VISIT(c, expr, s->v.If.test);
         ADDOP_JABS(c, POP_JUMP_IF_FALSE, next);
         VISIT_SEQ(c, stmt, s->v.If.body);
-        ADDOP_JREL(c, JUMP_FORWARD, end);
-        if (s->v.If.orelse) {
+        if (asdl_seq_LEN(s->v.If.orelse)) {
+            ADDOP_JREL(c, JUMP_FORWARD, end);
             compiler_use_next_block(c, next);
             VISIT_SEQ(c, stmt, s->v.If.orelse);
         }

-- 
Repository URL: http://hg.python.org/cpython


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