def get_target(self, offset, extended_arg=0):
"""
Get next instruction offset for op located at given <offset>.
NOTE: extended_arg is no longer used
"""
inst = self.get_inst(offset)
if inst.opcode in self.opc.JREL_OPS | self.opc.JABS_OPS:
target = inst.argval
else:
# No jump offset, so use fall-through offset
target = next_offset(inst.opcode, self.opc, inst.offset)
return target
def detect_control_flow(self, offset, targets, inst_index):
"""
Detect structures and their boundaries to fix optimized jumps
Python 3.0 is more like Python 2.6 than it is Python 3.x.
So we have a special routine here.
"""
code = self.code
op = code[offset]
# Detect parent structure
parent = self.structs[0]
start = parent['start']
end = parent['end']
# Pick inner-most parent for our offset
for struct in self.structs:
current_start = struct['start']
current_end = struct['end']
if ((current_start <= offset < current_end)
and (current_start >= start and current_end <= end)):
start = current_start
end = current_end
parent = struct
if op == self.opc.SETUP_LOOP:
# We categorize loop types: 'for', 'while', 'while 1' with
# possibly suffixes '-loop' and '-else'
# Try to find the jump_back instruction of the loop.
# It could be a return instruction.
start += instruction_size(op, self.opc)
target = self.get_target(offset)
end = self.restrict_to_parent(target, parent)
self.setup_loop_targets[offset] = target
self.setup_loops[target] = offset
if target != end:
self.fixed_jumps[offset] = end
(line_no, next_line_byte) = self.lines[offset]
jump_back = self.last_instr(start, end, self.opc.JUMP_ABSOLUTE,
next_line_byte, False)
if jump_back:
jump_forward_offset = next_offset(code[jump_back], self.opc,
jump_back)
else:
jump_forward_offset = None
return_val_offset1 = self.prev[self.prev[end]]
if (jump_back and jump_back != self.prev_op[end]
and self.is_jump_forward(jump_forward_offset)):
if (code[self.prev_op[end]] == self.opc.RETURN_VALUE or
(code[self.prev_op[end]] == self.opc.POP_BLOCK
and code[return_val_offset1] == self.opc.RETURN_VALUE)):
jump_back = None
if not jump_back:
# loop suite ends in return
jump_back = self.last_instr(start, end, self.opc.RETURN_VALUE)
if not jump_back:
return
jump_back += 2
if_offset = None
if code[self.prev_op[next_line_byte]] not in JUMP_TF:
if_offset = self.prev[next_line_byte]
if if_offset:
loop_type = 'while'
self.ignore_if.add(if_offset)
else:
loop_type = 'for'
target = next_line_byte
end = jump_back + 3
else:
if self.get_target(jump_back, 0) >= next_line_byte:
jump_back = self.last_instr(start, end,
self.opc.JUMP_ABSOLUTE, start,
False)
if end > jump_back + 4 and self.is_jump_forward(end):
if self.is_jump_forward(jump_back + 4):
if self.get_target(jump_back +
4) == self.get_target(end):
self.fixed_jumps[offset] = jump_back + 4
end = jump_back + 4
elif target < offset:
self.fixed_jumps[offset] = jump_back + 4
end = jump_back + 4
target = self.get_target(jump_back, 0)
if code[target] in (self.opc.FOR_ITER, self.opc.GET_ITER):
loop_type = 'for'
else:
loop_type = 'while'
test = self.prev_op[next_line_byte]
if test == offset:
loop_type = 'while 1'
elif self.code[test] in self.opc.JUMP_OPs:
self.ignore_if.add(test)
test_target = self.get_target(test)
if test_target > (jump_back + 3):
jump_back = test_target
self.not_continue.add(jump_back)
self.loops.append(target)
self.structs.append({
'type': loop_type + '-loop',
'start': target,
'end': jump_back
})
after_jump_offset = xdis.next_offset(code[jump_back], self.opc,
jump_back)
if after_jump_offset != end:
self.structs.append({
'type': loop_type + '-else',
'start': after_jump_offset,
'end': end
})
elif op in self.pop_jump_tf:
start = offset + instruction_size(op, self.opc)
target = self.get_target(offset)
rtarget = self.restrict_to_parent(target, parent)
prev_op = self.prev_op
# Do not let jump to go out of parent struct bounds
if target != rtarget and parent['type'] == 'and/or':
self.fixed_jumps[offset] = rtarget
return
# Does this jump to right after another conditional jump that is
# not myself? If so, it's part of a larger conditional.
# rocky: if we have a conditional jump to the next instruction, then
# possibly I am "skipping over" a "pass" or null statement.
if ((code[prev_op[target]] in self.pop_jump_if_pop)
and (target > offset) and prev_op[target] != offset):
self.fixed_jumps[offset] = prev_op[target]
self.structs.append({
'type': 'and/or',
'start': start,
'end': prev_op[target]
})
return
# The op offset just before the target jump offset is important
# in making a determination of what we have. Save that.
pre_rtarget = prev_op[rtarget]
# Is it an "and" inside an "if" or "while" block
if op == opc.JUMP_IF_FALSE:
# Search for another JUMP_IF_FALSE targetting the same op,
# in current statement, starting from current offset, and filter
# everything inside inner 'or' jumps and midline ifs
match = self.rem_or(start, self.next_stmt[offset],
opc.JUMP_IF_FALSE, target)
# If we still have any offsets in set, start working on it
if match:
is_jump_forward = self.is_jump_forward(pre_rtarget)
if (is_jump_forward and pre_rtarget not in self.stmts
and self.restrict_to_parent(
self.get_target(pre_rtarget),
parent) == rtarget):
if (code[prev_op[pre_rtarget]]
== self.opc.JUMP_ABSOLUTE
and self.remove_mid_line_ifs([offset])
and target == self.get_target(
prev_op[pre_rtarget]) and
(prev_op[pre_rtarget] not in self.stmts
or self.get_target(prev_op[pre_rtarget]) >
prev_op[pre_rtarget]) and 1 == len(
self.remove_mid_line_ifs(
self.rem_or(start, prev_op[pre_rtarget],
JUMP_TF, target)))):
pass
elif (code[prev_op[pre_rtarget]]
== self.opc.RETURN_VALUE
and self.remove_mid_line_ifs([offset])
and 1 == (len(
set(
self.remove_mid_line_ifs(
self.rem_or(start,
prev_op[pre_rtarget],
JUMP_TF, target)))
| set(
self.remove_mid_line_ifs(
self.rem_or(
start, prev_op[pre_rtarget],
(opc.JUMP_IF_FALSE,
opc.JUMP_IF_TRUE,
opc.JUMP_ABSOLUTE
), pre_rtarget, True)))))):
pass
else:
fix = None
jump_ifs = self.all_instr(start,
self.next_stmt[offset],
opc.JUMP_IF_FALSE)
last_jump_good = True
for j in jump_ifs:
if target == self.get_target(j):
if self.lines[
j].next == j + 3 and last_jump_good:
fix = j
break
else:
last_jump_good = False
self.fixed_jumps[offset] = fix or match[-1]
return
else:
self.fixed_jumps[offset] = match[-1]
return
# op == JUMP_IF_TRUE
else:
next = self.next_stmt[offset]
if prev_op[next] == offset:
pass
elif self.is_jump_forward(next) and target == self.get_target(
next):
if code[prev_op[next]] == opc.JUMP_IF_FALSE:
if (code[next] == self.opc.JUMP_FORWARD
or target != rtarget
or code[prev_op[pre_rtarget]]
not in (self.opc.JUMP_ABSOLUTE,
self.opc.RETURN_VALUE)):
self.fixed_jumps[offset] = prev_op[next]
return
elif (code[next] == self.opc.JUMP_ABSOLUTE
and self.is_jump_forward(target)
and self.get_target(target) == self.get_target(next)):
self.fixed_jumps[offset] = prev_op[next]
return
# Don't add a struct for a while test, it's already taken care of
if offset in self.ignore_if:
return
if (code[pre_rtarget] == self.opc.JUMP_ABSOLUTE
and pre_rtarget in self.stmts and pre_rtarget != offset
and prev_op[pre_rtarget] != offset
and not (code[rtarget] == self.opc.JUMP_ABSOLUTE
and code[rtarget + 3] == self.opc.POP_BLOCK
and code[prev_op[pre_rtarget]] !=
self.opc.JUMP_ABSOLUTE)):
rtarget = pre_rtarget
# Does the "jump if" jump beyond a jump op?
# That is, we have something like:
# JUMP_IF_FALSE HERE
# ...
# JUMP_FORWARD
# HERE:
#
# If so, this can be block inside an "if" statement
# or a conditional assignment like:
# x = 1 if x else 2
#
# There are other contexts we may need to consider
# like whether the target is "END_FINALLY"
# or if the condition jump is to a forward location
if self.is_jump_forward(pre_rtarget):
if_end = self.get_target(pre_rtarget, 0)
# If the jump target is back, we are looping
if (if_end < pre_rtarget
and (code[prev_op[if_end]] == self.opc.SETUP_LOOP)):
if (if_end > start):
return
end = self.restrict_to_parent(if_end, parent)
self.structs.append({
'type': 'if-then',
'start': start,
'end': pre_rtarget
})
self.not_continue.add(pre_rtarget)
# if rtarget < end and (
# code[rtarget] not in (self.opc.END_FINALLY,
# self.opc.JUMP_ABSOLUTE) and
# code[prev_op[pre_rtarget]] not in (self.opc.POP_EXCEPT,
# self.opc.END_FINALLY)):
# self.structs.append({'type': 'else',
# 'start': rtarget,
# 'end': end})
# self.else_start[rtarget] = end
elif self.is_jump_back(pre_rtarget, 0):
if_end = rtarget
self.structs.append({
'type': 'if-then',
'start': start,
'end': pre_rtarget
})
self.not_continue.add(pre_rtarget)
elif code[pre_rtarget] in (self.opc.RETURN_VALUE,
self.opc.BREAK_LOOP):
self.structs.append({
'type': 'if-then',
'start': start,
'end': rtarget
})
# It is important to distingish if this return is inside some sort
# except block return
jump_prev = prev_op[offset]
if self.is_pypy and code[jump_prev] == self.opc.COMPARE_OP:
if self.opc.cmp_op[code[jump_prev +
1]] == 'exception-match':
return
if self.version >= 3.5:
# Python 3.5 may remove as dead code a JUMP
# instruction after a RETURN_VALUE. So we check
# based on seeing SETUP_EXCEPT various places.
if code[rtarget] == self.opc.SETUP_EXCEPT:
return
# Check that next instruction after pops and jump is
# not from SETUP_EXCEPT
next_op = rtarget
if code[next_op] == self.opc.POP_BLOCK:
next_op += instruction_size(self.code[next_op],
self.opc)
if code[next_op] == self.opc.JUMP_ABSOLUTE:
next_op += instruction_size(self.code[next_op],
self.opc)
if next_op in targets:
for try_op in targets[next_op]:
come_from_op = code[try_op]
if come_from_op == self.opc.SETUP_EXCEPT:
return
pass
pass
if code[pre_rtarget] == self.opc.RETURN_VALUE:
self.return_end_ifs.add(pre_rtarget)
else:
self.fixed_jumps[offset] = rtarget
self.not_continue.add(pre_rtarget)
elif op == self.opc.SETUP_EXCEPT:
target = self.get_target(offset)
end = self.restrict_to_parent(target, parent)
self.fixed_jumps[offset] = end
elif op == self.opc.SETUP_FINALLY:
target = self.get_target(offset)
end = self.restrict_to_parent(target, parent)
self.fixed_jumps[offset] = end
elif op in self.jump_if_pop:
target = self.get_target(offset)
if target > offset:
unop_target = self.last_instr(offset, target,
self.opc.JUMP_FORWARD, target)
if unop_target and code[unop_target + 3] != self.opc.ROT_TWO:
self.fixed_jumps[offset] = unop_target
else:
self.fixed_jumps[offset] = self.restrict_to_parent(
target, parent)
pass
pass
elif self.version >= 3.5:
# 3.5+ has Jump optimization which too often causes RETURN_VALUE to get
# misclassified as RETURN_END_IF. Handle that here.
# In RETURN_VALUE, JUMP_ABSOLUTE, RETURN_VALUE is never RETURN_END_IF
if op == self.opc.RETURN_VALUE:
if (offset + 1 < len(code)
and code[offset + 1] == self.opc.JUMP_ABSOLUTE
and offset in self.return_end_ifs):
self.return_end_ifs.remove(offset)
pass
pass
elif op == self.opc.JUMP_FORWARD:
# If we have:
# JUMP_FORWARD x, [non-jump, insns], RETURN_VALUE, x:
# then RETURN_VALUE is not RETURN_END_IF
rtarget = self.get_target(offset)
rtarget_prev = self.prev[rtarget]
if (code[rtarget_prev] == self.opc.RETURN_VALUE
and rtarget_prev in self.return_end_ifs):
i = rtarget_prev
while i != offset:
if code[i] in [opc.JUMP_FORWARD, opc.JUMP_ABSOLUTE]:
return
i = self.prev[i]
self.return_end_ifs.remove(rtarget_prev)
pass
return