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mamba.py
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mamba.py
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import marshal
import opcode
import operator
import types
class MutableByteCode():
def __init__(self, code):
self.bytes = bytearray(code.co_code)
self.consts = list(code.co_consts)
self.names = list(code.co_names)
def opargAtIndex(bytes, i):
return bytes[i] + (bytes[i + 1] << 8)
def setConstOpargAtIndex(byteCode, index, value):
newOparg = len(byteCode.consts)
byteCode.consts.append(value)
byteCode.bytes[index] = newOparg & 0xFF
byteCode.bytes[index + 1] = (newOparg >> 8) & 0xFF
def nextOp(bytes, i):
op = bytes[i]
opname = opcode.opname[op]
oparg = None
bytesConsumed = 1
if op >= opcode.HAVE_ARGUMENT:
oparg = opargAtIndex(bytes, i + 1)
bytesConsumed = 3
return (op, opname, oparg, bytesConsumed)
def opsInBytes(bytes):
ops = []
i = 0
l = len(bytes)
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
ops.append(op)
i += bytesConsumed
return ops
def countOpCodes(byteCode):
""" Reports the number of opcodes in the given bytecode.
Note the number of opcodes does not always equal the number of
bytes since opcodes can have a two byte argument.
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
count = 0
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
i += bytesConsumed
count += 1
print "Found {0} opcodes".format(count)
def findConstantLiterals(byteCode):
""" Finds all declarations of constant literals.
Returns a dictionary of {varName: byteIndex}
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
constLiterals = {}
loadConstOp = opcode.opmap['LOAD_CONST']
storeNameOp = opcode.opmap['STORE_NAME']
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
if op == loadConstOp and not isinstance(byteCode.consts[oparg], types.CodeType):
(op2, opname2, oparg2, bytesConsumed2) = nextOp(bytes, i + bytesConsumed)
if op2 == storeNameOp:
varName = byteCode.names[oparg2]
constLiterals[varName] = i
bytesConsumed += bytesConsumed2
i += bytesConsumed
return constLiterals
def findFunctionDeclarations(byteCode):
"""Finds all function declarations in the given bytecode.
"""
bytes = byteCode.bytes
l = len(bytes) - 9
i = 0
decls = {}
loadConstOp = opcode.opmap['LOAD_CONST']
makeFunctionOp = opcode.opmap['MAKE_FUNCTION']
storeNameOp = opcode.opmap['STORE_NAME']
while i < l:
if bytes[i] == loadConstOp and bytes[i + 3] == makeFunctionOp and bytes[i + 6] == storeNameOp:
funcName = byteCode.names[opargAtIndex(bytes, i + 7)]
decls[funcName] = i
i += 1
return decls
def performConstantPropagation(byteCode):
""" Replaces LOAD_NAME with LOAD_CONST for constant literal variables
Scans for LOAD_NAME and replaces it with LOAD_CONST if the variable
name being loaded was previous detected as:
LOAD_CONST
STORE_NAME
LOAD_NAME and LOAD_CONST both occupy 3 bytes.
todo: this is too agressive, breaks:
i = 0
while i < 10:
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
modifications = 0
constLiterals = findConstantLiterals(byteCode)
loadConstOp = opcode.opmap['LOAD_CONST']
loadNameOp = opcode.opmap['LOAD_NAME']
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
if op == loadNameOp:
varName = byteCode.names[oparg]
if varName in constLiterals:
valueIndex = constLiterals[varName]
bytes[i] = loadConstOp
bytes[i + 1] = bytes[valueIndex + 1];
bytes[i + 2] = bytes[valueIndex + 2];
print "** Propagated {} as constant literal @ byte {}".format(varName, i)
modifications += 1
i += bytesConsumed
return modifications
def performConstantFolding(byteCode):
"""Replaces operations such as 5 + 7 with 12 at compile time.
Here we are looking for a LOAD_CONST LOAD_CONST _SAFE_OP_
Where _SAFE_OP_ is one of:
BINARY_ADD
BINARY_SUBTRACT
Or LOAD_CONST _SAFE_OP_
Where _SAFE_OP_ is one of:
UNARY_NOT
todo: special case LOAD_CONST UNARY_NOT UNARY_NOT to prevent a pass
todo: check if foldedValue is already in byteCode.consts and reuse index
"""
bytes = byteCode.bytes
l = len(bytes)
i = 3
modifications = 0
loadConstOp = opcode.opmap['LOAD_CONST']
unaryNotOp = opcode.opmap['UNARY_NOT']
nopOp = opcode.opmap['NOP']
foldableOps = {
opcode.opmap['BINARY_ADD'] : ('+', operator.add),
opcode.opmap['BINARY_SUBTRACT'] : ('-', operator.sub),
}
while i < l:
if i > 5 and bytes[i] in foldableOps and bytes[i - 3] == loadConstOp and bytes[i - 6] == loadConstOp:
value1 = byteCode.consts[opargAtIndex(bytes, i - 5)]
value2 = byteCode.consts[opargAtIndex(bytes, i - 2)]
if not isinstance(value1, types.CodeType) and not isinstance(value2, types.CodeType):
token, func = foldableOps[bytes[i]]
foldedValue = func(value1, value2)
setConstOpargAtIndex(byteCode, i - 5, foldedValue)
for byteIndex in range(i - 3, i + 1):
bytes[byteIndex] = nopOp
print "** Folded {} {} {} to {} @ byte {}".format(value1, token, value2, foldedValue, i)
modifications += 1
elif bytes[i] == unaryNotOp and bytes[i - 3] == loadConstOp:
constValue = byteCode.consts[opargAtIndex(bytes, i - 2)]
if not isinstance(constValue, types.CodeType):
foldedValue = not constValue
setConstOpargAtIndex(byteCode, i - 2, foldedValue)
bytes[i] = nopOp
print "** Folded not {} to {} @ byte {}".format(constValue, foldedValue, i)
modifications += 1
i += 1
return modifications
def removeUnusedVariables(byteCode):
"""Detects variables that are not referenced after their declaration and removes them.
Curently only variables that are set to constant literal values are supported.
Variable declarations are replaced with 6 NOPs (3 for LOAD_CONST and 3 for STORE_NAME).
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
modifications = 0
constLiterals = findConstantLiterals(byteCode)
loadNameOp = opcode.opmap['LOAD_NAME']
nopOp = opcode.opmap['NOP']
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
if op == loadNameOp:
varName = byteCode.names[oparg]
if varName in constLiterals:
del constLiterals[varName]
i += bytesConsumed
for varName, byteIndex in constLiterals.iteritems():
for i in range(byteIndex, byteIndex + 6):
bytes[i] = nopOp
print "** Removed unused var {} @ byte {}".format(varName, byteIndex + 3)
modifications += 1
return modifications
def collapseConstantIfs(byteCode):
"""Detects constant if expressions and inlines the appropriate body
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
modifications = 0
loadConstOp = opcode.opmap['LOAD_CONST']
jumpIfFalseOp = opcode.opmap['POP_JUMP_IF_FALSE']
jumpForwardOp = opcode.opmap['JUMP_FORWARD']
nopOp = opcode.opmap['NOP']
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
if op == loadConstOp and not isinstance(byteCode.consts[oparg], types.CodeType):
constValue = byteCode.consts[oparg]
(op2, opname2, oparg2, bytesConsumed2) = nextOp(bytes, i + bytesConsumed)
if op2 == jumpIfFalseOp:
bytesConsumed += bytesConsumed2
if not constValue:
for index in range(i, oparg2):
bytes[index] = nopOp
else:
for index in range(i, i + 6):
bytes[index] = nopOp
for index in range(i + 6, l):
if bytes[index] == jumpForwardOp:
(op3, opname3, oparg3, bytesConsumed3) = nextOp(bytes, index)
bytesConsumed += bytesConsumed3
for index2 in range(index, index + bytesConsumed3 + oparg3):
bytes[index2] = nopOp
break
print "** Collapsed constant if statement @ byte " + str(i + 3)
modifications += 1
i += bytesConsumed
return modifications
def inlineFunctions(byteCode):
"""Inlines functions which are deemed pure and within an acceptable bytecode size.
Ideal candidates for inlining are those that will result in further constant
propagation and folding. Currently only functions called with constant values are
considered, however this is not completely necessary.
todo: be smarter about finding nops to overwrite
todo: expand scope of this optimization since Python function calls are expensive.
"""
bytes = byteCode.bytes
l = len(bytes)
i = 9
modifications = 0
loadNameOp = opcode.opmap['LOAD_NAME']
loadConstOp = opcode.opmap['LOAD_CONST']
callFunctionOp = opcode.opmap['CALL_FUNCTION']
nopOp = opcode.opmap['NOP']
inlineWhitelist = set((opcode.opmap['LOAD_FAST'],
opcode.opmap['LOAD_CONST'],
opcode.opmap['BINARY_ADD'],
opcode.opmap['RETURN_VALUE']))
inlineMaxOps = 10
while i < l:
if bytes[i] == callFunctionOp and bytes[i - 3] == loadConstOp and bytes[i - 6] == loadNameOp:
funcNameOparg = opargAtIndex(bytes, i - 5)
funcName = byteCode.names[funcNameOparg]
func = None
for index in range(0, len(byteCode.consts)):
if isinstance(byteCode.consts[index], types.CodeType):
if byteCode.consts[index].co_name == funcName:
func = byteCode.consts[index]
break
if func is not None:
bytesToInline = bytearray(func.co_code)
opsToInline = opsInBytes(bytesToInline)
inlineOpsLen = len(opsToInline)
if inlineOpsLen >= inlineMaxOps:
continue
canInline = True
for op in opsToInline:
if op not in inlineWhitelist:
canInline = False
break
if not canInline:
continue
bytes[i - 6] = nopOp
bytes[i - 5] = nopOp
bytes[i - 4] = nopOp
bytes[i] = nopOp
bytes[i + 1] = nopOp
bytes[i + 2] = nopOp
bytes[i:i] = bytesToInline[3:len(bytesToInline) - 1]
funcConstValue = func.co_consts[opargAtIndex(bytes, i + 1)]
setConstOpargAtIndex(byteCode, i + 1, funcConstValue)
print "** Inlined call to function {} @ byte {}".format(funcName, i)
modifications += 1
i += 1
return modifications
def removeUnusedFunctions(byteCode):
"""Removes functions that are not used.
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
modifications = 0
decls = findFunctionDeclarations(byteCode)
loadNameOp = opcode.opmap['LOAD_NAME']
nopOp = opcode.opmap['NOP']
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
if op == loadNameOp:
name = byteCode.names[oparg]
if name in decls:
del decls[name]
i += bytesConsumed
for name, byteIndex in decls.iteritems():
for byteToClear in range(byteIndex, byteIndex + 9):
bytes[byteToClear] = nopOp
print "** Removed unused function {} @ byte {}".format(name, byteIndex)
modifications += 1
return modifications
def translateBoolToNotNot(byteCode):
"""Translates bool(const) to not not const
Perhaps due largely to function call overhead, bool(const) is significantly
slower than not not const
"""
bytes = byteCode.bytes
l = len(bytes)
i = 6
modifications = 0
callFunctionOp = opcode.opmap['CALL_FUNCTION']
loadConstOp = opcode.opmap['LOAD_CONST']
loadNameOp = opcode.opmap['LOAD_NAME']
unaryNotOp = opcode.opmap['UNARY_NOT']
nopOp = opcode.opmap['NOP']
while i < l:
if bytes[i] == callFunctionOp and bytes[i - 3] == loadConstOp and bytes[i - 6] == loadNameOp:
oparg1 = opargAtIndex(bytes, i - 2)
oparg2 = opargAtIndex(bytes, i - 5)
if not isinstance(oparg1, types.CodeType) and code.co_names[oparg2] == 'bool':
bytes[i - 6] = bytes[i - 3]
bytes[i - 5] = bytes[i - 2]
bytes[i - 4] = bytes[i - 1]
bytes[i - 3] = unaryNotOp
bytes[i - 2] = unaryNotOp
for nopIndex in range(i - 1, i + 3):
bytes[nopIndex] = nopOp
constValue = byteCode.consts[oparg1]
print "** Replaced bool({}) with not not {} @ byte {}".format(constValue, constValue, i)
modifications += 1
i += 2
i += 1
return modifications
def removeNops(byteCode):
"""Remove all NOPs from the given bytecode.
Optimization passes that replace instructions with instructions that
fill fewer bytes than previously occupied will fill the remaining space
with NOPs. This step cannot be a simple filter where byte[i] != NOP
since any op arg byte set to NOP will be removed.
"""
bytes = byteCode.bytes
l = len(bytes)
i = 0
filteredBytes = bytearray()
nopOp = opcode.opmap['NOP']
nopsRemoved = 0
while i < l:
op = bytes[i]
bytesConsumed = 1
if op != nopOp:
filteredBytes.append(op)
if op >= opcode.HAVE_ARGUMENT:
filteredBytes.append(bytes[i + 1])
filteredBytes.append(bytes[i + 2])
bytesConsumed += 2
else:
nopsRemoved += 1
i += bytesConsumed
if nopsRemoved > 0:
print "** Removed {} NOPs".format(nopsRemoved)
byteCode.bytes = filteredBytes
return nopsRemoved
def printCode(byteCode):
bytes = byteCode.bytes
l = len(bytes)
i = 0
while i < l:
(op, opname, oparg, bytesConsumed) = nextOp(bytes, i)
desc = None
if op >= opcode.HAVE_ARGUMENT:
if op in opcode.hasconst:
desc = byteCode.consts[oparg]
#if isinstance(constCode, types.CodeType):
# printCode(constCode)
elif op in opcode.hasname:
desc = byteCode.names[oparg]
#elif op in opcode.haslocal:
# print "haslocal"
#elif op in opcode.hascompare:
# print "hascompare"
#elif op in opcode.hasfree:
# print "hasfree"
elif op in opcode.hasjrel:
desc = oparg
elif op in opcode.hasjabs:
desc = oparg
if op >= opcode.HAVE_ARGUMENT:
print "[{}] {} ({})".format(i, opname, desc)
else:
print "[{}] {}".format(i, opname)
i += bytesConsumed
try:
f = open("demo.pyc", "rb")
_ = f.read(8)
code = marshal.load(f)
finally:
f.close()
byteCode = MutableByteCode(code)
preBytesLen = len(byteCode.bytes)
print "Original bytecode:\n"
printCode(byteCode)
countOpCodes(byteCode)
passes = 0
while passes < 100:
print "\nPass {}:".format(passes + 1)
modifications = 0
# generic compiler optimizations
modifications += performConstantPropagation(byteCode)
modifications += performConstantFolding(byteCode)
modifications += collapseConstantIfs(byteCode)
modifications += removeUnusedVariables(byteCode)
modifications += inlineFunctions(byteCode)
modifications += removeUnusedFunctions(byteCode)
# python specific optimizations
modifications += translateBoolToNotNot(byteCode)
# remove nop placeholders
modifications += removeNops(byteCode)
if modifications == 0:
print "No modifications made"
print "Bytecode has been optimized\n"
break
passes += 1
if passes == 100:
print "Stopped optimizing due to 100 passes\n"
# todo: clean up co_consts, etc
print "Optimized bytecode:\n"
printCode(byteCode)
countOpCodes(byteCode)
postBytesLen = len(byteCode.bytes)
print "Went from {} to {} bytes".format(preBytesLen, postBytesLen)