# ______________________________________________________________________ from __future__ import absolute_import import dis import opcode from .bytecode_visitor import BasicBlockVisitor from . import opcode_util # ______________________________________________________________________ class BytecodeFlowBuilder (BasicBlockVisitor): '''Transforms a CFG into a bytecode "flow tree". The flow tree is a Python dictionary, described loosely by the following set of productions: * `flow_tree` ``:=`` ``{`` `blocks` ``*`` ``}`` * `blocks` ``:=`` `block_index` ``:`` ``[`` `bytecode_tree` ``*`` ``]`` * `bytecode_tree` ``:=`` ``(`` `opcode_index` ``,`` `opcode` ``,`` `opname` ``,`` `arg` ``,`` ``[`` `bytecode_tree` ``*`` ``]`` ``)`` The primary purpose of this transformation is to simulate the value stack, removing it and any stack-specific opcodes.''' def __init__ (self, *args, **kws): super(BytecodeFlowBuilder, self).__init__(*args, **kws) om_items = opcode_util.OPCODE_MAP.items() self.opmap = dict((opcode.opmap[opname], (opname, pops, pushes, stmt)) for opname, (pops, pushes, stmt) in om_items if opname in opcode.opmap) def _visit_op (self, i, op, arg, opname, pops, pushes, appends): assert pops is not None, ('%s not well defined in opcode_util.' 'OPCODE_MAP' % opname) if pops: if pops < 0: pops = arg - pops - 1 assert pops <= len(self.stack), ("Stack underflow at instruction " "%d (%s)!" % (i, opname)) stk_args = self.stack[-pops:] del self.stack[-pops:] else: stk_args = [] ret_val = (i, op, opname, arg, stk_args) if pushes: self.stack.append(ret_val) if appends: self.block.append(ret_val) return ret_val def _op (self, i, op, arg): opname, pops, pushes, appends = self.opmap[op] return self._visit_op(i, op, arg, opname, pops, pushes, appends) def visit_cfg (self, cfg): self.cfg = cfg ret_val = self.visit(cfg.blocks) del self.cfg return ret_val def enter_blocks (self, blocks): labels = list(blocks.keys()) labels.sort() self.blocks = dict((index, []) for index in labels) self.loop_stack = [] self.stacks = {} def exit_blocks (self, blocks): ret_val = self.blocks del self.stacks del self.loop_stack del self.blocks return ret_val def enter_block (self, block): self.block_no = block self.block = self.blocks[block] in_blocks = self.cfg.blocks_in[block] if len(in_blocks) == 0: self.stack = [] else: pred_stack = None for pred in in_blocks: if pred in self.stacks: pred_stack = self.stacks[pred] break if pred_stack is not None: self.stack = pred_stack[:] else: raise NotImplementedError() def exit_block (self, block): assert self.block_no == block self.stacks[block] = self.stack del self.stack del self.block del self.block_no op_BINARY_ADD = _op op_BINARY_AND = _op op_BINARY_DIVIDE = _op op_BINARY_FLOOR_DIVIDE = _op op_BINARY_LSHIFT = _op op_BINARY_MODULO = _op op_BINARY_MULTIPLY = _op op_BINARY_OR = _op op_BINARY_POWER = _op op_BINARY_RSHIFT = _op op_BINARY_SUBSCR = _op op_BINARY_SUBTRACT = _op op_BINARY_TRUE_DIVIDE = _op op_BINARY_XOR = _op def op_BREAK_LOOP (self, i, op, arg): loop_i, _, loop_arg = self.loop_stack[-1] assert arg is None return self._op(i, op, loop_i + loop_arg + 3) #op_BUILD_CLASS = _op op_BUILD_LIST = _op op_BUILD_MAP = _op op_BUILD_SLICE = _op op_BUILD_TUPLE = _op op_CALL_FUNCTION = _op op_CALL_FUNCTION_KW = _op op_CALL_FUNCTION_VAR = _op op_CALL_FUNCTION_VAR_KW = _op op_COMPARE_OP = _op #op_CONTINUE_LOOP = _op op_DELETE_ATTR = _op op_DELETE_FAST = _op op_DELETE_GLOBAL = _op op_DELETE_NAME = _op op_DELETE_SLICE = _op op_DELETE_SUBSCR = _op def op_DUP_TOP (self, i, op, arg): self.stack.append(self.stack[-1]) def op_DUP_TOPX (self, i, op, arg): self.stack += self.stack[-arg:] #op_END_FINALLY = _op op_EXEC_STMT = _op #op_EXTENDED_ARG = _op op_FOR_ITER = _op op_GET_ITER = _op op_IMPORT_FROM = _op op_IMPORT_NAME = _op op_IMPORT_STAR = _op op_INPLACE_ADD = _op op_INPLACE_AND = _op op_INPLACE_DIVIDE = _op op_INPLACE_FLOOR_DIVIDE = _op op_INPLACE_LSHIFT = _op op_INPLACE_MODULO = _op op_INPLACE_MULTIPLY = _op op_INPLACE_OR = _op op_INPLACE_POWER = _op op_INPLACE_RSHIFT = _op op_INPLACE_SUBTRACT = _op op_INPLACE_TRUE_DIVIDE = _op op_INPLACE_XOR = _op op_JUMP_ABSOLUTE = _op op_JUMP_FORWARD = _op def op_JUMP_IF_FALSE (self, i, op, arg): opname, _, _, _ = self.opmap[op] ret_val = (i, op, opname, arg, [self.stack[-1]]) self.block.append(ret_val) return ret_val op_JUMP_IF_TRUE = op_JUMP_IF_FALSE op_LIST_APPEND = _op op_LOAD_ATTR = _op op_LOAD_CLOSURE = _op op_LOAD_CONST = _op op_LOAD_DEREF = _op op_LOAD_FAST = _op op_LOAD_GLOBAL = _op op_LOAD_LOCALS = _op op_LOAD_NAME = _op op_MAKE_CLOSURE = _op op_MAKE_FUNCTION = _op op_NOP = _op def op_POP_BLOCK (self, i, op, arg): self.loop_stack.pop() return self._op(i, op, arg) op_POP_JUMP_IF_FALSE = _op op_POP_JUMP_IF_TRUE = _op op_POP_TOP = _op op_PRINT_EXPR = _op op_PRINT_ITEM = _op op_PRINT_ITEM_TO = _op op_PRINT_NEWLINE = _op op_PRINT_NEWLINE_TO = _op op_RAISE_VARARGS = _op op_RETURN_VALUE = _op def op_ROT_FOUR (self, i, op, arg): self.stack[-4:] = (self.stack[-1], self.stack[-4], self.stack[-3], self.stack[-2]) def op_ROT_THREE (self, i, op, arg): self.stack[-3:] = (self.stack[-1], self.stack[-3], self.stack[-2]) def op_ROT_TWO (self, i, op, arg): self.stack[-2:] = (self.stack[-1], self.stack[-2]) #op_SETUP_EXCEPT = _op #op_SETUP_FINALLY = _op def op_SETUP_LOOP (self, i, op, arg): self.loop_stack.append((i, op, arg)) self.block.append((i, op, self.opnames[op], arg, [])) op_SLICE = _op #op_STOP_CODE = _op op_STORE_ATTR = _op op_STORE_DEREF = _op op_STORE_FAST = _op op_STORE_GLOBAL = _op op_STORE_MAP = _op op_STORE_NAME = _op op_STORE_SLICE = _op op_STORE_SUBSCR = _op op_UNARY_CONVERT = _op op_UNARY_INVERT = _op op_UNARY_NEGATIVE = _op op_UNARY_NOT = _op op_UNARY_POSITIVE = _op op_UNPACK_SEQUENCE = _op #op_WITH_CLEANUP = _op op_YIELD_VALUE = _op # ______________________________________________________________________ def build_flow (func): '''Given a Python function, return a bytecode flow tree for that function.''' import byte_control cfg = byte_control.build_cfg(func) return BytecodeFlowBuilder().visit_cfg(cfg) # ______________________________________________________________________ # Main (self-test) routine def main (*args): import pprint from tests import llfuncs if not args: args = ('doslice',) for arg in args: pprint.pprint(build_flow(getattr(llfuncs, arg))) # ______________________________________________________________________ if __name__ == '__main__': import sys main(*sys.argv[1:]) # ______________________________________________________________________ # End of byte_flow.py