Produce cleaner bytecode for 'with' and 'async with' by generating separate code for normal and exceptional paths. (#6641)

Remove BEGIN_FINALLY, END_FINALLY, CALL_FINALLY and POP_FINALLY bytecodes. Implement finally blocks by code duplication.
Reimplement frame.lineno setter using line numbers rather than bytecode offsets.

1 files changed, 54 insertions, 33 deletions

diff --git a/Lib/test/test_dis.py b/Lib/test/test_dis.py
index fecf203..5c15952 100644
--- a/Lib/test/test_dis.py
+++ b/Lib/test/test_dis.py
@@ -278,32 +278,34 @@ dis_traceback = """\
     -->       6 BINARY_TRUE_DIVIDE
               8 POP_TOP
              10 POP_BLOCK
-             12 JUMP_FORWARD            40 (to 54)
+             12 JUMP_FORWARD            44 (to 58)
 
 %3d     >>   14 DUP_TOP
              16 LOAD_GLOBAL              0 (Exception)
              18 COMPARE_OP              10 (exception match)
-             20 POP_JUMP_IF_FALSE       52
+             20 POP_JUMP_IF_FALSE       56
              22 POP_TOP
              24 STORE_FAST               0 (e)
              26 POP_TOP
-             28 SETUP_FINALLY           10 (to 40)
+             28 SETUP_FINALLY           18 (to 48)
 
 %3d          30 LOAD_FAST                0 (e)
              32 LOAD_ATTR                1 (__traceback__)
              34 STORE_FAST               1 (tb)
              36 POP_BLOCK
-             38 BEGIN_FINALLY
-        >>   40 LOAD_CONST               0 (None)
+             38 POP_EXCEPT
+             40 LOAD_CONST               0 (None)
              42 STORE_FAST               0 (e)
              44 DELETE_FAST              0 (e)
-             46 END_FINALLY
-             48 POP_EXCEPT
-             50 JUMP_FORWARD             2 (to 54)
-        >>   52 END_FINALLY
-
-%3d     >>   54 LOAD_FAST                1 (tb)
-             56 RETURN_VALUE
+             46 JUMP_FORWARD            10 (to 58)
+        >>   48 LOAD_CONST               0 (None)
+             50 STORE_FAST               0 (e)
+             52 DELETE_FAST              0 (e)
+             54 RERAISE
+        >>   56 RERAISE
+
+%3d     >>   58 LOAD_FAST                1 (tb)
+             60 RETURN_VALUE
 """ % (TRACEBACK_CODE.co_firstlineno + 1,
        TRACEBACK_CODE.co_firstlineno + 2,
        TRACEBACK_CODE.co_firstlineno + 3,
@@ -752,7 +754,7 @@ Argument count:    0
 Positional-only arguments: 0
 Kw-only arguments: 0
 Number of locals:  2
-Stack size:        10
+Stack size:        9
 Flags:             OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
 Constants:
    0: None
@@ -977,10 +979,10 @@ expected_opinfo_jumpy = [
   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=96, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=98, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=100, starts_line=None, is_jump_target=False),
-  Instruction(opname='SETUP_FINALLY', opcode=122, arg=70, argval=174, argrepr='to 174', offset=102, starts_line=20, is_jump_target=True),
+  Instruction(opname='SETUP_FINALLY', opcode=122, arg=98, argval=202, argrepr='to 202', offset=102, starts_line=20, is_jump_target=True),
   Instruction(opname='SETUP_FINALLY', opcode=122, arg=12, argval=118, argrepr='to 118', offset=104, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=106, starts_line=21, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=8, argval=0, argrepr='0', offset=108, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=108, starts_line=None, is_jump_target=False),
   Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=110, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=112, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=114, starts_line=None, is_jump_target=False),
@@ -993,33 +995,47 @@ expected_opinfo_jumpy = [
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=128, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=130, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=132, starts_line=23, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Here we go, here we go, here we go...', argrepr="'Here we go, here we go, here we go...'", offset=134, starts_line=None, 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=134, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=136, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=138, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=140, starts_line=None, is_jump_target=False),
-  Instruction(opname='JUMP_FORWARD', opcode=110, arg=26, argval=170, argrepr='to 170', offset=142, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=144, starts_line=None, is_jump_target=True),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=46, argval=190, argrepr='to 190', offset=142, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=48, arg=None, argval=None, argrepr='', offset=144, starts_line=None, is_jump_target=True),
   Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=146, starts_line=25, is_jump_target=True),
-  Instruction(opname='SETUP_WITH', opcode=143, arg=14, argval=164, argrepr='to 164', offset=148, starts_line=None, is_jump_target=False),
+  Instruction(opname='SETUP_WITH', opcode=143, arg=24, argval=174, argrepr='to 174', offset=148, starts_line=None, is_jump_target=False),
   Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=150, starts_line=None, is_jump_target=False),
   Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=152, starts_line=26, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval='Never reach this', argrepr="'Never reach this'", offset=154, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=154, starts_line=None, is_jump_target=False),
   Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=156, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=158, starts_line=None, is_jump_target=False),
   Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=160, starts_line=None, is_jump_target=False),
-  Instruction(opname='BEGIN_FINALLY', opcode=53, arg=None, argval=None, argrepr='', offset=162, starts_line=None, is_jump_target=False),
-  Instruction(opname='WITH_CLEANUP_START', opcode=81, arg=None, argval=None, argrepr='', offset=164, starts_line=None, is_jump_target=True),
-  Instruction(opname='WITH_CLEANUP_FINISH', opcode=82, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=168, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=True),
-  Instruction(opname='BEGIN_FINALLY', opcode=53, 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=174, starts_line=28, is_jump_target=True),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=176, starts_line=None, is_jump_target=False),
-  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=178, starts_line=None, is_jump_target=False),
-  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=False),
-  Instruction(opname='END_FINALLY', opcode=88, arg=None, argval=None, argrepr='', offset=182, starts_line=None, is_jump_target=False),
-  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=184, starts_line=None, is_jump_target=False),
-  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=162, starts_line=None, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=164, starts_line=None, is_jump_target=False),
+  Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=3, argval=3, argrepr='', offset=168, 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='JUMP_FORWARD', opcode=110, arg=16, argval=190, argrepr='to 190', offset=172, starts_line=None, is_jump_target=False),
+  Instruction(opname='WITH_EXCEPT_START', opcode=49, arg=None, argval=None, argrepr='', offset=174, starts_line=None, is_jump_target=True),
+  Instruction(opname='POP_JUMP_IF_TRUE', opcode=115, arg=180, argval=180, argrepr='', offset=176, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=48, arg=None, argval=None, argrepr='', offset=178, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=True),
+  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=184, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=188, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=190, starts_line=None, is_jump_target=True),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=192, starts_line=28, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=10, argval="OK, now we're done", argrepr='"OK, now we\'re done"', offset=194, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=196, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=198, starts_line=None, is_jump_target=False),
+  Instruction(opname='JUMP_FORWARD', opcode=110, arg=10, argval=212, argrepr='to 212', offset=200, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=202, starts_line=None, 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=204, starts_line=None, is_jump_target=False),
+  Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=206, starts_line=None, is_jump_target=False),
+  Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=208, starts_line=None, is_jump_target=False),
+  Instruction(opname='RERAISE', opcode=48, arg=None, argval=None, argrepr='', offset=210, starts_line=None, is_jump_target=False),
+  Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=212, starts_line=None, is_jump_target=True),
+  Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=214, starts_line=None, is_jump_target=False)
 ]
 
 # One last piece of inspect fodder to check the default line number handling
@@ -1032,6 +1048,10 @@ expected_opinfo_simple = [
 
 class InstructionTests(BytecodeTestCase):
 
+    def __init__(self, *args):
+        super().__init__(*args)
+        self.maxDiff = None
+
     def test_default_first_line(self):
         actual = dis.get_instructions(simple)
         self.assertEqual(list(actual), expected_opinfo_simple)
@@ -1063,6 +1083,7 @@ class InstructionTests(BytecodeTestCase):
 # get_instructions has its own tests above, so can rely on it to validate
 # the object oriented API
 class BytecodeTests(unittest.TestCase):
+
     def test_instantiation(self):
         # Test with function, method, code string and code object
         for obj in [_f, _C(1).__init__, "a=1", _f.__code__]: