mirror of https://github.com/python/cpython
542 lines
16 KiB
Python
542 lines
16 KiB
Python
"""A flow graph representation for Python bytecode"""
|
|
|
|
import dis
|
|
import new
|
|
import string
|
|
import types
|
|
|
|
from compiler import misc
|
|
|
|
class FlowGraph:
|
|
def __init__(self):
|
|
self.current = self.entry = Block()
|
|
self.exit = Block("exit")
|
|
self.blocks = misc.Set()
|
|
self.blocks.add(self.entry)
|
|
self.blocks.add(self.exit)
|
|
|
|
def startBlock(self, block):
|
|
self.current = block
|
|
|
|
def nextBlock(self, block=None):
|
|
if block is None:
|
|
block = self.newBlock()
|
|
# XXX think we need to specify when there is implicit transfer
|
|
# from one block to the next
|
|
#
|
|
# I think this strategy works: each block has a child
|
|
# designated as "next" which is returned as the last of the
|
|
# children. because the nodes in a graph are emitted in
|
|
# reverse post order, the "next" block will always be emitted
|
|
# immediately after its parent.
|
|
# Worry: maintaining this invariant could be tricky
|
|
self.current.addNext(block)
|
|
self.startBlock(block)
|
|
|
|
def newBlock(self):
|
|
b = Block()
|
|
self.blocks.add(b)
|
|
return b
|
|
|
|
def startExitBlock(self):
|
|
self.startBlock(self.exit)
|
|
|
|
def emit(self, *inst):
|
|
# XXX should jump instructions implicitly call nextBlock?
|
|
if inst[0] == 'RETURN_VALUE':
|
|
self.current.addOutEdge(self.exit)
|
|
self.current.emit(inst)
|
|
|
|
def getBlocks(self):
|
|
"""Return the blocks in reverse postorder
|
|
|
|
i.e. each node appears before all of its successors
|
|
"""
|
|
# XXX make sure every node that doesn't have an explicit next
|
|
# is set so that next points to exit
|
|
for b in self.blocks.elements():
|
|
if b is self.exit:
|
|
continue
|
|
if not b.next:
|
|
b.addNext(self.exit)
|
|
order = dfs_postorder(self.entry, {})
|
|
order.reverse()
|
|
# hack alert
|
|
if not self.exit in order:
|
|
order.append(self.exit)
|
|
return order
|
|
|
|
def dfs_postorder(b, seen):
|
|
"""Depth-first search of tree rooted at b, return in postorder"""
|
|
order = []
|
|
seen[b] = b
|
|
for c in b.children():
|
|
if seen.has_key(c):
|
|
continue
|
|
order = order + dfs_postorder(c, seen)
|
|
order.append(b)
|
|
return order
|
|
|
|
class Block:
|
|
_count = 0
|
|
|
|
def __init__(self, label=''):
|
|
self.insts = []
|
|
self.inEdges = misc.Set()
|
|
self.outEdges = misc.Set()
|
|
self.label = label
|
|
self.bid = Block._count
|
|
self.next = []
|
|
Block._count = Block._count + 1
|
|
|
|
def __repr__(self):
|
|
if self.label:
|
|
return "<block %s id=%d len=%d>" % (self.label, self.bid,
|
|
len(self.insts))
|
|
else:
|
|
return "<block id=%d len=%d>" % (self.bid, len(self.insts))
|
|
|
|
def __str__(self):
|
|
insts = map(str, self.insts)
|
|
return "<block %s %d:\n%s>" % (self.label, self.bid,
|
|
string.join(insts, '\n'))
|
|
|
|
def emit(self, inst):
|
|
op = inst[0]
|
|
if op[:4] == 'JUMP':
|
|
self.outEdges.add(inst[1])
|
|
self.insts.append(inst)
|
|
|
|
def getInstructions(self):
|
|
return self.insts
|
|
|
|
def addInEdge(self, block):
|
|
self.inEdges.add(block)
|
|
|
|
def addOutEdge(self, block):
|
|
self.outEdges.add(block)
|
|
|
|
def addNext(self, block):
|
|
self.next.append(block)
|
|
assert len(self.next) == 1, map(str, self.next)
|
|
|
|
def children(self):
|
|
return self.outEdges.elements() + self.next
|
|
|
|
# flags for code objects
|
|
CO_OPTIMIZED = 0x0001
|
|
CO_NEWLOCALS = 0x0002
|
|
CO_VARARGS = 0x0004
|
|
CO_VARKEYWORDS = 0x0008
|
|
|
|
# the FlowGraph is transformed in place; it exists in one of these states
|
|
RAW = "RAW"
|
|
FLAT = "FLAT"
|
|
CONV = "CONV"
|
|
DONE = "DONE"
|
|
|
|
class PyFlowGraph(FlowGraph):
|
|
super_init = FlowGraph.__init__
|
|
|
|
def __init__(self, name, filename, args=(), optimized=0):
|
|
self.super_init()
|
|
self.name = name
|
|
self.filename = filename
|
|
self.docstring = None
|
|
self.args = args # XXX
|
|
self.argcount = getArgCount(args)
|
|
if optimized:
|
|
self.flags = CO_OPTIMIZED | CO_NEWLOCALS
|
|
else:
|
|
self.flags = 0
|
|
self.consts = []
|
|
self.names = []
|
|
self.varnames = list(args) or []
|
|
for i in range(len(self.varnames)):
|
|
var = self.varnames[i]
|
|
if isinstance(var, TupleArg):
|
|
self.varnames[i] = var.getName()
|
|
self.stage = RAW
|
|
|
|
def setDocstring(self, doc):
|
|
self.docstring = doc
|
|
self.consts.insert(0, doc)
|
|
|
|
def setFlag(self, flag):
|
|
self.flags = self.flags | flag
|
|
if flag == CO_VARARGS:
|
|
self.argcount = self.argcount - 1
|
|
|
|
def getCode(self):
|
|
"""Get a Python code object"""
|
|
if self.stage == RAW:
|
|
self.flattenGraph()
|
|
if self.stage == FLAT:
|
|
self.convertArgs()
|
|
if self.stage == CONV:
|
|
self.makeByteCode()
|
|
if self.stage == DONE:
|
|
return self.newCodeObject()
|
|
raise RuntimeError, "inconsistent PyFlowGraph state"
|
|
|
|
def dump(self, io=None):
|
|
if io:
|
|
save = sys.stdout
|
|
sys.stdout = io
|
|
pc = 0
|
|
for t in self.insts:
|
|
opname = t[0]
|
|
if opname == "SET_LINENO":
|
|
print
|
|
if len(t) == 1:
|
|
print "\t", "%3d" % pc, opname
|
|
pc = pc + 1
|
|
else:
|
|
print "\t", "%3d" % pc, opname, t[1]
|
|
pc = pc + 3
|
|
if io:
|
|
sys.stdout = save
|
|
|
|
def flattenGraph(self):
|
|
"""Arrange the blocks in order and resolve jumps"""
|
|
assert self.stage == RAW
|
|
self.insts = insts = []
|
|
pc = 0
|
|
begin = {}
|
|
end = {}
|
|
for b in self.getBlocks():
|
|
begin[b] = pc
|
|
for inst in b.getInstructions():
|
|
insts.append(inst)
|
|
if len(inst) == 1:
|
|
pc = pc + 1
|
|
else:
|
|
# arg takes 2 bytes
|
|
pc = pc + 3
|
|
end[b] = pc
|
|
pc = 0
|
|
for i in range(len(insts)):
|
|
inst = insts[i]
|
|
if len(inst) == 1:
|
|
pc = pc + 1
|
|
else:
|
|
pc = pc + 3
|
|
opname = inst[0]
|
|
if self.hasjrel.has_elt(opname):
|
|
oparg = inst[1]
|
|
offset = begin[oparg] - pc
|
|
insts[i] = opname, offset
|
|
elif self.hasjabs.has_elt(opname):
|
|
insts[i] = opname, begin[inst[1]]
|
|
self.stacksize = findDepth(self.insts)
|
|
self.stage = FLAT
|
|
|
|
hasjrel = misc.Set()
|
|
for i in dis.hasjrel:
|
|
hasjrel.add(dis.opname[i])
|
|
hasjabs = misc.Set()
|
|
for i in dis.hasjabs:
|
|
hasjabs.add(dis.opname[i])
|
|
|
|
def convertArgs(self):
|
|
"""Convert arguments from symbolic to concrete form"""
|
|
assert self.stage == FLAT
|
|
for i in range(len(self.insts)):
|
|
t = self.insts[i]
|
|
if len(t) == 2:
|
|
opname = t[0]
|
|
oparg = t[1]
|
|
conv = self._converters.get(opname, None)
|
|
if conv:
|
|
self.insts[i] = opname, conv(self, oparg)
|
|
self.stage = CONV
|
|
|
|
def _lookupName(self, name, list):
|
|
"""Return index of name in list, appending if necessary"""
|
|
if name in list:
|
|
i = list.index(name)
|
|
# this is cheap, but incorrect in some cases, e.g 2 vs. 2L
|
|
if type(name) == type(list[i]):
|
|
return i
|
|
for i in range(len(list)):
|
|
elt = list[i]
|
|
if type(elt) == type(name) and elt == name:
|
|
return i
|
|
end = len(list)
|
|
list.append(name)
|
|
return end
|
|
|
|
_converters = {}
|
|
def _convert_LOAD_CONST(self, arg):
|
|
return self._lookupName(arg, self.consts)
|
|
|
|
def _convert_LOAD_FAST(self, arg):
|
|
self._lookupName(arg, self.names)
|
|
return self._lookupName(arg, self.varnames)
|
|
_convert_STORE_FAST = _convert_LOAD_FAST
|
|
_convert_DELETE_FAST = _convert_LOAD_FAST
|
|
|
|
def _convert_NAME(self, arg):
|
|
return self._lookupName(arg, self.names)
|
|
_convert_LOAD_NAME = _convert_NAME
|
|
_convert_STORE_NAME = _convert_NAME
|
|
_convert_DELETE_NAME = _convert_NAME
|
|
_convert_IMPORT_NAME = _convert_NAME
|
|
_convert_IMPORT_FROM = _convert_NAME
|
|
_convert_STORE_ATTR = _convert_NAME
|
|
_convert_LOAD_ATTR = _convert_NAME
|
|
_convert_DELETE_ATTR = _convert_NAME
|
|
_convert_LOAD_GLOBAL = _convert_NAME
|
|
_convert_STORE_GLOBAL = _convert_NAME
|
|
_convert_DELETE_GLOBAL = _convert_NAME
|
|
|
|
_cmp = list(dis.cmp_op)
|
|
def _convert_COMPARE_OP(self, arg):
|
|
return self._cmp.index(arg)
|
|
|
|
# similarly for other opcodes...
|
|
|
|
for name, obj in locals().items():
|
|
if name[:9] == "_convert_":
|
|
opname = name[9:]
|
|
_converters[opname] = obj
|
|
del name, obj, opname
|
|
|
|
def makeByteCode(self):
|
|
assert self.stage == CONV
|
|
self.lnotab = lnotab = LineAddrTable()
|
|
for t in self.insts:
|
|
opname = t[0]
|
|
if len(t) == 1:
|
|
lnotab.addCode(self.opnum[opname])
|
|
else:
|
|
oparg = t[1]
|
|
if opname == "SET_LINENO":
|
|
lnotab.nextLine(oparg)
|
|
hi, lo = twobyte(oparg)
|
|
try:
|
|
lnotab.addCode(self.opnum[opname], lo, hi)
|
|
except ValueError:
|
|
print opname, oparg
|
|
print self.opnum[opname], lo, hi
|
|
raise
|
|
self.stage = DONE
|
|
|
|
opnum = {}
|
|
for num in range(len(dis.opname)):
|
|
opnum[dis.opname[num]] = num
|
|
del num
|
|
|
|
def newCodeObject(self):
|
|
assert self.stage == DONE
|
|
if self.flags == 0:
|
|
nlocals = 0
|
|
else:
|
|
nlocals = len(self.varnames)
|
|
argcount = self.argcount
|
|
if self.flags & CO_VARKEYWORDS:
|
|
argcount = argcount - 1
|
|
return new.code(argcount, nlocals, self.stacksize, self.flags,
|
|
self.lnotab.getCode(), self.getConsts(),
|
|
tuple(self.names), tuple(self.varnames),
|
|
self.filename, self.name, self.lnotab.firstline,
|
|
self.lnotab.getTable())
|
|
|
|
def getConsts(self):
|
|
"""Return a tuple for the const slot of the code object
|
|
|
|
Must convert references to code (MAKE_FUNCTION) to code
|
|
objects recursively.
|
|
"""
|
|
l = []
|
|
for elt in self.consts:
|
|
if isinstance(elt, PyFlowGraph):
|
|
elt = elt.getCode()
|
|
l.append(elt)
|
|
return tuple(l)
|
|
|
|
def isJump(opname):
|
|
if opname[:4] == 'JUMP':
|
|
return 1
|
|
|
|
class TupleArg:
|
|
"""Helper for marking func defs with nested tuples in arglist"""
|
|
def __init__(self, count, names):
|
|
self.count = count
|
|
self.names = names
|
|
def __repr__(self):
|
|
return "TupleArg(%s, %s)" % (self.count, self.names)
|
|
def getName(self):
|
|
return ".nested%d" % self.count
|
|
|
|
def getArgCount(args):
|
|
argcount = len(args)
|
|
if args:
|
|
for arg in args:
|
|
if isinstance(arg, TupleArg):
|
|
numNames = len(misc.flatten(arg.names))
|
|
argcount = argcount - numNames
|
|
return argcount
|
|
|
|
def twobyte(val):
|
|
"""Convert an int argument into high and low bytes"""
|
|
assert type(val) == types.IntType
|
|
return divmod(val, 256)
|
|
|
|
class LineAddrTable:
|
|
"""lnotab
|
|
|
|
This class builds the lnotab, which is undocumented but described
|
|
by com_set_lineno in compile.c. Here's an attempt at explanation:
|
|
|
|
For each SET_LINENO instruction after the first one, two bytes are
|
|
added to lnotab. (In some cases, multiple two-byte entries are
|
|
added.) The first byte is the distance in bytes between the
|
|
instruction for the last SET_LINENO and the current SET_LINENO.
|
|
The second byte is offset in line numbers. If either offset is
|
|
greater than 255, multiple two-byte entries are added -- one entry
|
|
for each factor of 255.
|
|
"""
|
|
|
|
def __init__(self):
|
|
self.code = []
|
|
self.codeOffset = 0
|
|
self.firstline = 0
|
|
self.lastline = 0
|
|
self.lastoff = 0
|
|
self.lnotab = []
|
|
|
|
def addCode(self, *args):
|
|
for arg in args:
|
|
self.code.append(chr(arg))
|
|
self.codeOffset = self.codeOffset + len(args)
|
|
|
|
def nextLine(self, lineno):
|
|
if self.firstline == 0:
|
|
self.firstline = lineno
|
|
self.lastline = lineno
|
|
else:
|
|
# compute deltas
|
|
addr = self.codeOffset - self.lastoff
|
|
line = lineno - self.lastline
|
|
while addr > 0 or line > 0:
|
|
# write the values in 1-byte chunks that sum
|
|
# to desired value
|
|
trunc_addr = addr
|
|
trunc_line = line
|
|
if trunc_addr > 255:
|
|
trunc_addr = 255
|
|
if trunc_line > 255:
|
|
trunc_line = 255
|
|
self.lnotab.append(trunc_addr)
|
|
self.lnotab.append(trunc_line)
|
|
addr = addr - trunc_addr
|
|
line = line - trunc_line
|
|
self.lastline = lineno
|
|
self.lastoff = self.codeOffset
|
|
|
|
def getCode(self):
|
|
return string.join(self.code, '')
|
|
|
|
def getTable(self):
|
|
return string.join(map(chr, self.lnotab), '')
|
|
|
|
class StackDepthTracker:
|
|
# XXX 1. need to keep track of stack depth on jumps
|
|
# XXX 2. at least partly as a result, this code is broken
|
|
|
|
def findDepth(self, insts):
|
|
depth = 0
|
|
maxDepth = 0
|
|
for i in insts:
|
|
opname = i[0]
|
|
delta = self.effect.get(opname, 0)
|
|
if delta > 1:
|
|
depth = depth + delta
|
|
elif delta < 0:
|
|
if depth > maxDepth:
|
|
maxDepth = depth
|
|
depth = depth + delta
|
|
else:
|
|
if depth > maxDepth:
|
|
maxDepth = depth
|
|
# now check patterns
|
|
for pat, pat_delta in self.patterns:
|
|
if opname[:len(pat)] == pat:
|
|
delta = pat_delta
|
|
depth = depth + delta
|
|
break
|
|
# if we still haven't found a match
|
|
if delta == 0:
|
|
meth = getattr(self, opname, None)
|
|
if meth is not None:
|
|
depth = depth + meth(i[1])
|
|
if depth < 0:
|
|
depth = 0
|
|
return maxDepth
|
|
|
|
effect = {
|
|
'POP_TOP': -1,
|
|
'DUP_TOP': 1,
|
|
'SLICE+1': -1,
|
|
'SLICE+2': -1,
|
|
'SLICE+3': -2,
|
|
'STORE_SLICE+0': -1,
|
|
'STORE_SLICE+1': -2,
|
|
'STORE_SLICE+2': -2,
|
|
'STORE_SLICE+3': -3,
|
|
'DELETE_SLICE+0': -1,
|
|
'DELETE_SLICE+1': -2,
|
|
'DELETE_SLICE+2': -2,
|
|
'DELETE_SLICE+3': -3,
|
|
'STORE_SUBSCR': -3,
|
|
'DELETE_SUBSCR': -2,
|
|
# PRINT_EXPR?
|
|
'PRINT_ITEM': -1,
|
|
'LOAD_LOCALS': 1,
|
|
'RETURN_VALUE': -1,
|
|
'EXEC_STMT': -2,
|
|
'BUILD_CLASS': -2,
|
|
'STORE_NAME': -1,
|
|
'STORE_ATTR': -2,
|
|
'DELETE_ATTR': -1,
|
|
'STORE_GLOBAL': -1,
|
|
'BUILD_MAP': 1,
|
|
'COMPARE_OP': -1,
|
|
'STORE_FAST': -1,
|
|
}
|
|
# use pattern match
|
|
patterns = [
|
|
('BINARY_', -1),
|
|
('LOAD_', 1),
|
|
('IMPORT_', 1),
|
|
]
|
|
|
|
# special cases:
|
|
# UNPACK_SEQUENCE, BUILD_TUPLE,
|
|
# BUILD_LIST, CALL_FUNCTION, MAKE_FUNCTION, BUILD_SLICE
|
|
def UNPACK_SEQUENCE(self, count):
|
|
return count
|
|
def BUILD_TUPLE(self, count):
|
|
return -count
|
|
def BUILD_LIST(self, count):
|
|
return -count
|
|
def CALL_FUNCTION(self, argc):
|
|
hi, lo = divmod(argc, 256)
|
|
return lo + hi * 2
|
|
def CALL_FUNCTION_VAR(self, argc):
|
|
return self.CALL_FUNCTION(argc)+1
|
|
def CALL_FUNCTION_KW(self, argc):
|
|
return self.CALL_FUNCTION(argc)+1
|
|
def CALL_FUNCTION_VAR_KW(self, argc):
|
|
return self.CALL_FUNCTION(argc)+2
|
|
def MAKE_FUNCTION(self, argc):
|
|
return -argc
|
|
def BUILD_SLICE(self, argc):
|
|
if argc == 2:
|
|
return -1
|
|
elif argc == 3:
|
|
return -2
|
|
|
|
findDepth = StackDepthTracker().findDepth
|