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bpo-40222: "Zero cost" exception handling (GH-25729)

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"Zero cost" exception handling.

* Uses a lookup table to determine how to handle exceptions.
* Removes SETUP_FINALLY and POP_TOP block instructions, eliminating (most of) the runtime overhead of try statements.
* Reduces the size of the frame object by about 60%.
This commit is contained in:
Mark Shannon 2021-05-07 15:19:19 +01:00 • committed by GitHub
parent b32c8e9795
commit adcd220556
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
30 changed files with 6614 additions and 5687 deletions
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179
Lib/test/test_dis.py
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@ -282,42 +282,47 @@ dis_compound_stmt_str = """\
"""
dis_traceback = """\
%3d 0 SETUP_FINALLY 7 (to 16)
%3d 0 NOP
%3d 2 LOAD_CONST 1 (1)
4 LOAD_CONST 2 (0)
--> 6 BINARY_TRUE_DIVIDE
8 POP_TOP
10 POP_BLOCK
%3d 12 LOAD_FAST 1 (tb)
14 RETURN_VALUE
%3d 10 LOAD_FAST 1 (tb)
12 RETURN_VALUE
>> 14 PUSH_EXC_INFO
%3d >> 16 DUP_TOP
%3d 16 DUP_TOP
18 LOAD_GLOBAL 0 (Exception)
20 JUMP_IF_NOT_EXC_MATCH 29 (to 58)
20 JUMP_IF_NOT_EXC_MATCH 28 (to 56)
22 POP_TOP
24 STORE_FAST 0 (e)
26 POP_TOP
28 SETUP_FINALLY 10 (to 50)
%3d 30 LOAD_FAST 0 (e)
32 LOAD_ATTR 1 (__traceback__)
34 STORE_FAST 1 (tb)
36 POP_BLOCK
38 POP_EXCEPT
40 LOAD_CONST 0 (None)
42 STORE_FAST 0 (e)
44 DELETE_FAST 0 (e)
%3d 28 LOAD_FAST 0 (e)
30 LOAD_ATTR 1 (__traceback__)
32 STORE_FAST 1 (tb)
34 POP_EXCEPT
36 LOAD_CONST 0 (None)
38 STORE_FAST 0 (e)
40 DELETE_FAST 0 (e)
%3d 46 LOAD_FAST 1 (tb)
48 RETURN_VALUE
>> 50 LOAD_CONST 0 (None)
52 STORE_FAST 0 (e)
54 DELETE_FAST 0 (e)
56 RERAISE 1
%3d 42 LOAD_FAST 1 (tb)
44 RETURN_VALUE
>> 46 LOAD_CONST 0 (None)
48 STORE_FAST 0 (e)
50 DELETE_FAST 0 (e)
52 RERAISE 1
>> 54 POP_EXCEPT_AND_RERAISE
%3d >> 58 RERAISE 0
%3d >> 56 RERAISE 0
ExceptionTable:
2 to 8 -> 14 [0]
14 to 26 -> 54 [3] lasti
28 to 32 -> 46 [3] lasti
46 to 52 -> 54 [3] lasti
56 to 56 -> 54 [3] lasti
""" % (TRACEBACK_CODE.co_firstlineno + 1,
TRACEBACK_CODE.co_firstlineno + 2,
TRACEBACK_CODE.co_firstlineno + 5,
@ -360,38 +365,46 @@ def _tryfinallyconst(b):
b()
dis_tryfinally = """\
%3d 0 SETUP_FINALLY 6 (to 14)
%3d 0 NOP
%3d 2 LOAD_FAST 0 (a)
4 POP_BLOCK
%3d 6 LOAD_FAST 1 (b)
8 CALL_FUNCTION 0
10 POP_TOP
12 RETURN_VALUE
>> 14 LOAD_FAST 1 (b)
%3d 4 LOAD_FAST 1 (b)
6 CALL_FUNCTION 0
8 POP_TOP
10 RETURN_VALUE
>> 12 PUSH_EXC_INFO
14 LOAD_FAST 1 (b)
16 CALL_FUNCTION 0
18 POP_TOP
20 RERAISE 0
>> 22 POP_EXCEPT_AND_RERAISE
ExceptionTable:
2 to 2 -> 12 [0]
12 to 20 -> 22 [3] lasti
""" % (_tryfinally.__code__.co_firstlineno + 1,
_tryfinally.__code__.co_firstlineno + 2,
_tryfinally.__code__.co_firstlineno + 4,
)
dis_tryfinallyconst = """\
%3d 0 SETUP_FINALLY 6 (to 14)
%3d 0 NOP
%3d 2 POP_BLOCK
%3d 2 NOP
%3d 4 LOAD_FAST 0 (b)
6 CALL_FUNCTION 0
8 POP_TOP
10 LOAD_CONST 1 (1)
12 RETURN_VALUE
>> 14 LOAD_FAST 0 (b)
16 CALL_FUNCTION 0
18 POP_TOP
20 RERAISE 0
14 PUSH_EXC_INFO
16 LOAD_FAST 0 (b)
18 CALL_FUNCTION 0
20 POP_TOP
22 RERAISE 0
>> 24 POP_EXCEPT_AND_RERAISE
ExceptionTable:
14 to 22 -> 24 [3] lasti
""" % (_tryfinallyconst.__code__.co_firstlineno + 1,
_tryfinallyconst.__code__.co_firstlineno + 2,
_tryfinallyconst.__code__.co_firstlineno + 4,
@ -833,7 +846,7 @@ Argument count: 0
Positional-only arguments: 0
Kw-only arguments: 0
Number of locals: 2
Stack size: 9
Stack size: 10
Flags: OPTIMIZED, NEWLOCALS, NOFREE, COROUTINE
Constants:
0: None
@ -1059,61 +1072,64 @@ 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=98, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=100, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=102, starts_line=None, is_jump_target=False),
Instruction(opname='SETUP_FINALLY', opcode=122, arg=48, argval=202, argrepr='to 202', offset=104, starts_line=20, is_jump_target=True),
Instruction(opname='SETUP_FINALLY', opcode=122, arg=6, argval=120, argrepr='to 120', offset=106, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=5, argval=1, argrepr='1', offset=108, starts_line=21, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=7, argval=0, argrepr='0', offset=110, starts_line=None, is_jump_target=False),
Instruction(opname='BINARY_TRUE_DIVIDE', opcode=27, arg=None, argval=None, argrepr='', offset=112, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=114, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=116, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=12, argval=144, argrepr='to 144', offset=118, starts_line=None, is_jump_target=False),
Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=120, starts_line=22, is_jump_target=True),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=122, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_IF_NOT_EXC_MATCH', opcode=121, arg=106, argval=212, argrepr='to 212', offset=124, starts_line=None, is_jump_target=False),
Instruction(opname='NOP', opcode=9, arg=None, argval=None, argrepr='', offset=104, starts_line=20, is_jump_target=True),
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=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='JUMP_FORWARD', opcode=110, arg=14, argval=144, argrepr='to 144', offset=114, starts_line=None, is_jump_target=False),
Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=116, starts_line=None, is_jump_target=False),
Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=118, starts_line=22, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=2, argval='ZeroDivisionError', argrepr='ZeroDivisionError', offset=120, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_IF_NOT_EXC_MATCH', opcode=121, arg=109, argval=218, argrepr='to 218', offset=122, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=124, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=126, starts_line=None, is_jump_target=False),
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=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=22, argval=188, argrepr='to 188', offset=142, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=130, 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=132, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=134, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=136, starts_line=None, is_jump_target=False),
Instruction(opname='POP_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=138, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=25, argval=192, argrepr='to 192', offset=140, starts_line=None, is_jump_target=False),
Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, arg=None, argval=None, argrepr='', offset=142, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_FAST', opcode=124, arg=0, argval='i', argrepr='i', offset=144, starts_line=25, is_jump_target=True),
Instruction(opname='SETUP_WITH', opcode=143, arg=12, argval=172, argrepr='to 172', offset=146, starts_line=None, is_jump_target=False),
Instruction(opname='BEFORE_WITH', opcode=53, arg=None, argval=None, argrepr='', offset=146, starts_line=None, is_jump_target=False),
Instruction(opname='STORE_FAST', opcode=125, arg=1, argval='dodgy', argrepr='dodgy', offset=148, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=150, starts_line=26, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=9, argval='Never reach this', argrepr="'Never reach this'", offset=152, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=154, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=156, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=158, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=160, starts_line=25, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=158, starts_line=25, is_jump_target=False),
Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', offset=160, starts_line=None, is_jump_target=False),
Instruction(opname='DUP_TOP', opcode=4, arg=None, argval=None, argrepr='', 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='CALL_FUNCTION', opcode=131, arg=3, argval=3, argrepr='', offset=166, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=168, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=8, argval=188, argrepr='to 188', offset=170, starts_line=None, is_jump_target=False),
Instruction(opname='WITH_EXCEPT_START', opcode=49, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=True),
Instruction(opname='POP_JUMP_IF_TRUE', opcode=115, arg=89, argval=178, argrepr='to 178', offset=174, starts_line=None, is_jump_target=False),
Instruction(opname='RERAISE', opcode=119, arg=1, argval=1, argrepr='', offset=176, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=178, starts_line=None, is_jump_target=True),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=180, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=3, argval=3, argrepr='', offset=164, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=166, starts_line=None, is_jump_target=False),
Instruction(opname='JUMP_FORWARD', opcode=110, arg=11, argval=192, argrepr='to 192', offset=168, starts_line=None, is_jump_target=False),
Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=170, starts_line=None, is_jump_target=False),
Instruction(opname='WITH_EXCEPT_START', opcode=49, arg=None, argval=None, argrepr='', offset=172, starts_line=None, is_jump_target=False),
Instruction(opname='POP_JUMP_IF_TRUE', opcode=115, arg=90, argval=180, argrepr='to 180', offset=174, starts_line=None, is_jump_target=False),
Instruction(opname='RERAISE', opcode=119, arg=4, argval=4, argrepr='', offset=176, starts_line=None, is_jump_target=False),
Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, 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_EXCEPT', opcode=89, arg=None, argval=None, argrepr='', offset=184, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=186, starts_line=None, is_jump_target=False),
Instruction(opname='POP_BLOCK', opcode=87, arg=None, argval=None, argrepr='', offset=188, starts_line=None, is_jump_target=True),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=190, 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=192, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=194, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=196, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=198, starts_line=None, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', 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=119, arg=0, argval=0, argrepr='', offset=210, starts_line=None, is_jump_target=False),
Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=212, starts_line=22, is_jump_target=True),
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_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=190, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=192, 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=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='LOAD_CONST', opcode=100, arg=0, argval=None, argrepr='None', offset=200, starts_line=None, is_jump_target=False),
Instruction(opname='RETURN_VALUE', opcode=83, arg=None, argval=None, argrepr='', offset=202, starts_line=None, is_jump_target=False),
Instruction(opname='PUSH_EXC_INFO', opcode=35, arg=None, argval=None, argrepr='', offset=204, starts_line=None, is_jump_target=False),
Instruction(opname='LOAD_GLOBAL', opcode=116, arg=1, argval='print', argrepr='print', offset=206, starts_line=None, 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=208, starts_line=None, is_jump_target=False),
Instruction(opname='CALL_FUNCTION', opcode=131, arg=1, argval=1, argrepr='', offset=210, starts_line=None, is_jump_target=False),
Instruction(opname='POP_TOP', opcode=1, arg=None, argval=None, argrepr='', offset=212, starts_line=None, is_jump_target=False),
Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=214, starts_line=None, is_jump_target=False),
Instruction(opname='POP_EXCEPT_AND_RERAISE', opcode=37, arg=None, argval=None, argrepr='', offset=216, starts_line=None, is_jump_target=False),
Instruction(opname='RERAISE', opcode=119, arg=0, argval=0, argrepr='', offset=218, starts_line=22, is_jump_target=True),
]
# One last piece of inspect fodder to check the default line number handling
@ -1211,6 +1227,7 @@ class BytecodeTests(unittest.TestCase):
self.assertEqual(b.current_offset, tb.tb_lasti)
def test_from_traceback_dis(self):
self.maxDiff = None
tb = get_tb()
b = dis.Bytecode.from_traceback(tb)
self.assertEqual(b.dis(), dis_traceback)