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Interval order COME_FROMs in Python3

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This bug had possibly caused lots of grammar pollution which may need
addressing.

We want to process COME_FROMs to the same offset to be in *descending*
order so we have the larger range or biggest instruction interval
last. (I think they are sorted in increasing order, but for safety
we sort them). That way, specific COME_FROM tags will match up
properly. For example, a "loop" with an "if" nested in it should have
the "loop" tag last so the grammar rule matches that properly

Adjust Python 3 grammar for more COME_FROM -> COME_FROM_LOOP. And
remove optional COME_FROM_LOOP where possible. Previously, the
optional-ness was a result of inner nestings gobbling up the
COME_FROM.

We'll probably want to go back and fix this up in Python2.
This commit is contained in:
rocky
2016-09-26 08:31:28 -04:00
parent c87710dd4b
commit 1fc8ac4700
5 changed files with 74 additions and 56 deletions
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14
HISTORY.md
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@@ -29,7 +29,9 @@ augmented with pseudo instruction COME_FROM. This code introduced
another clever idea: using table-driven semantics routines, using
format specifiers.
The last mention of a release of SPARK from John is around 2002.
The last mention of a release of SPARK from John is around 2002. As
released, although the Early Algorithm parser was in good shape, this
code was woefully lacking as serious Python deparser.
In the fall of 2000, Hartmut Goebel
[took over maintaining the code](https://groups.google.com/forum/#!searchin/comp.lang.python/hartmut$20goebel/comp.lang.python/35s3mp4-nuY/UZALti6ujnQJ). The
@@ -112,12 +114,18 @@ Fenx's uncompyle3 which I used for inspiration for Python3 support.
I started working on this late 2015, mostly to add fragment support.
In that, I decided to make this runnable on Python 3.2+ and Python 2.6+
while, handling Python bytecodes from Python versions 2.5+ and
3.2+.
3.2+. In doing so, it has been expedient to separate this into three
projects: load loading and disassembly (xdis), parsing and tree
building (spark_parser), and grammar and semantic actions for
decompiling (uncompyle6).
Over the many years, code styles and Python features have
changed. However brilliant the code was and still is, it hasn't really
had a single public active maintainer. And there have been many forks
of the code.
of the code. I have spent a great deal of time trying to organize and
modularize the code so that it can handle more Python versions more
gracefully (with still only moderate success).
That it has been in need of an overhaul has been recognized by the
Hartmut a decade an a half ago:

24
uncompyle6/parser.py
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@@ -174,9 +174,33 @@ class PythonParser(GenericASTBuilder):
else_suitec ::= c_stmts
else_suitec ::= return_stmts
stmt ::= assert
stmt ::= assert2
stmt ::= classdef
stmt ::= call_stmt
stmt ::= ifstmt
stmt ::= ifelsestmt
stmt ::= whilestmt
stmt ::= while1stmt
stmt ::= whileelsestmt
stmt ::= while1elsestmt
stmt ::= forstmt
stmt ::= forelsestmt
stmt ::= trystmt
stmt ::= tryelsestmt
stmt ::= tryfinallystmt
stmt ::= withstmt
stmt ::= withasstmt
stmt ::= del_stmt
del_stmt ::= DELETE_FAST
del_stmt ::= DELETE_NAME
del_stmt ::= DELETE_GLOBAL
stmt ::= return_stmt
return_stmt ::= ret_expr RETURN_VALUE
return_stmts ::= return_stmt

21
uncompyle6/parsers/parse2.py
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@@ -94,27 +94,6 @@ class Python2Parser(PythonParser):
stmt ::= exec_stmt
stmt ::= assert
stmt ::= assert2
stmt ::= ifstmt
stmt ::= ifelsestmt
stmt ::= whilestmt
stmt ::= while1stmt
stmt ::= whileelsestmt
stmt ::= while1elsestmt
stmt ::= forstmt
stmt ::= forelsestmt
stmt ::= trystmt
stmt ::= tryelsestmt
stmt ::= tryfinallystmt
stmt ::= withstmt
stmt ::= withasstmt
stmt ::= del_stmt
del_stmt ::= DELETE_FAST
del_stmt ::= DELETE_NAME
del_stmt ::= DELETE_GLOBAL
del_stmt ::= expr DELETE_SLICE+0
del_stmt ::= expr expr DELETE_SLICE+1
del_stmt ::= expr expr DELETE_SLICE+2

60
uncompyle6/parsers/parse3.py
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@@ -95,27 +95,6 @@ class Python3Parser(PythonParser):
raise_stmt2 ::= expr expr RAISE_VARARGS_2
raise_stmt3 ::= expr expr expr RAISE_VARARGS_3
stmt ::= assert
stmt ::= assert2
stmt ::= ifstmt
stmt ::= ifelsestmt
stmt ::= whilestmt
stmt ::= while1stmt
stmt ::= whileelsestmt
stmt ::= while1elsestmt
stmt ::= forstmt
stmt ::= forelsestmt
stmt ::= trystmt
stmt ::= tryelsestmt
stmt ::= tryfinallystmt
stmt ::= withstmt
stmt ::= withasstmt
stmt ::= del_stmt
del_stmt ::= DELETE_FAST
del_stmt ::= DELETE_NAME
del_stmt ::= DELETE_GLOBAL
del_stmt ::= delete_subscr
delete_subscr ::= expr expr DELETE_SUBSCR
del_stmt ::= expr DELETE_ATTR
@@ -301,20 +280,41 @@ class Python3Parser(PythonParser):
stmt ::= LOAD_CLOSURE RETURN_VALUE RETURN_LAST
stmt ::= whileTruestmt
ifelsestmt ::= testexpr c_stmts_opt JUMP_FORWARD else_suite _come_from
"""
forstmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK opt_come_from_loop
whilestmt ::= SETUP_LOOP testexpr l_stmts_opt JUMP_BACK POP_BLOCK opt_come_from_loop
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK POP_BLOCK opt_come_from_loop
def p_loop_stmt3(self, args):
"""
forstmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK
opt_come_from_loop
forelsestmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK else_suite
COME_FROM_LOOP
forelselaststmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK else_suitec
COME_FROM_LOOP
forelselaststmtl ::= SETUP_LOOP expr _for designator for_block POP_BLOCK else_suitel
COME_FROM_LOOP
whilestmt ::= SETUP_LOOP testexpr l_stmts_opt JUMP_BACK POP_BLOCK
COME_FROM_LOOP
whileelsestmt ::= SETUP_LOOP testexpr l_stmts_opt JUMP_BACK POP_BLOCK
else_suite COME_FROM_LOOP
whileelselaststmt ::= SETUP_LOOP testexpr l_stmts_opt JUMP_BACK POP_BLOCK
else_suitec COME_FROM_LOOP
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK POP_BLOCK
COME_FROM_LOOP
# Python < 3.5 no POP BLOCK
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK opt_come_from_loop
whileTruestmt ::= SETUP_LOOP return_stmts opt_come_from_loop
while1stmt ::= SETUP_LOOP l_stmts _come_from JUMP_BACK opt_come_from_loop
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK COME_FROM_LOOP
whileTruestmt ::= SETUP_LOOP return_stmts COME_FROM_LOOP
while1stmt ::= SETUP_LOOP l_stmts _come_from JUMP_BACK COME_FROM_LOOP
# FIXME: investigate - can code really produce a NOP?
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK NOP opt_come_from_loop
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK POP_BLOCK NOP opt_come_from_loop
forstmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK NOP opt_come_from_loop
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK NOP
COME_FROM_LOOP
whileTruestmt ::= SETUP_LOOP l_stmts_opt JUMP_BACK POP_BLOCK NOP
COME_FROM_LOOP
forstmt ::= SETUP_LOOP expr _for designator for_block POP_BLOCK NOP
COME_FROM_LOOP
"""
def p_genexpr3(self, args):

11
uncompyle6/scanners/scanner3.py
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@@ -198,14 +198,21 @@ class Scanner3(Scanner):
argval = inst.argval
if inst.offset in jump_targets:
jump_idx = 0
for jump_offset in jump_targets[inst.offset]:
# We want to process COME_FROMs to the same offset to be in *descending*
# offset order so we have the larger range or biggest instruction interval
# last. (I think they are sorted in increasing order, but for safety
# we sort them). That way, specific COME_FROM tags will match up
# properly. For example, a "loop" with an "if" nested in it should have the
# "loop" tag last so the grammar rule matches that properly.
for jump_offset in sorted(jump_targets[inst.offset], reverse=True):
come_from_name = 'COME_FROM'
if (inst.offset in offset_action):
action = offset_action[inst.offset]
if (action.type == 'end'
# Adjust the grammar and remove the below
and (self.opName(jump_offset)[len('SETUP_'):]
== action.name)
# After the grammar is fully adjusted, remove the below
# test
and action.name in ['EXCEPT', 'LOOP', 'WITH']):
come_from_name = '%s_%s' % (
(come_from_name, action.name))