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#!/usr/bin/env python3
# blockifyasm ----- Split disassembly into basic blocks ---------*- python -*-
#
# This source file is part of the Swift.org open source project
#
# Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
# Licensed under Apache License v2.0 with Runtime Library Exception
#
# See https://swift.org/LICENSE.txt for license information
# See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
#
# ----------------------------------------------------------------------------
#
# Splits a disassembled function from lldb into basic blocks.
#
# Useful to show the control flow graph of a disassembled function.
# The control flow graph can the be viewed with the viewcfg utility:
#
# (lldb) disassemble
# <copy-paste output to file.s>
# $ blockifyasm < file.s | viewcfg
#
# ----------------------------------------------------------------------------
import re
import sys
from collections import defaultdict
def help():
print(
"""\
Usage:
blockifyasm [-<n>] < file
-<n>: only match <n> significant digits of relative branch addresses
"""
)
def main():
addr_len = 16
if len(sys.argv) >= 2:
m = re.match("^-([0-9]+)$", sys.argv[1])
if m:
addr_len = int(m.group(1))
else:
help()
return
lines = []
block_starts = {}
branch_re1 = re.compile(r"^\s[-\s>]*0x.*:\s.* 0x([0-9a-f]+)\s*;\s*<[+-]")
branch_re2 = re.compile(r"^\s[-\s>]*0x.*:\s+tb.* 0x([0-9a-f]+)\s*(;.*)?")
inst_re = re.compile(r"^\s[-\s>]*0x([0-9a-f]+)[\s<>0-9+-]*:\s+([a-z0-9.]+)\s")
non_fall_through_insts = ["b", "ret", "brk", "jmp", "retq", "ud2"]
def get_branch_addr(line):
bm = branch_re1.match(line)
if bm:
return bm.group(1)[-addr_len:]
bm = branch_re2.match(line)
if bm:
return bm.group(1)[-addr_len:]
return None
def print_function():
if not lines:
return
predecessors = defaultdict(list)
block_num = -1
next_is_block = True
prev_is_fallthrough = False
# Collect predecessors for all blocks
for line in lines:
m = inst_re.match(line)
assert m, "non instruction line in function"
addr = m.group(1)[-addr_len:]
inst = m.group(2)
if next_is_block or addr in block_starts:
if prev_is_fallthrough:
predecessors[addr].append(block_num)
block_num += 1
block_starts[addr] = block_num
next_is_block = False
prev_is_fallthrough = True
br_addr = get_branch_addr(line)
if br_addr:
next_is_block = True
predecessors[br_addr].append(block_num)
prev_is_fallthrough = inst not in non_fall_through_insts
# Print the function with basic block labels
print("{")
for line in lines:
m = inst_re.match(line)
if m:
addr = m.group(1)[-addr_len:]
if addr in block_starts:
blockstr = "bb" + str(block_starts[addr]) + ":"
if predecessors[addr]:
print(
blockstr + " " * (55 - len(blockstr)) + "; preds = ", end=""
)
print(
", ".join("bb" + str(pred) for pred in predecessors[addr])
)
else:
print(blockstr)
br_addr = get_branch_addr(line)
if br_addr and block_starts[br_addr] >= 0:
line = re.sub(r";\s<[+-].*", "; bb" + str(block_starts[br_addr]), line)
print(line, end="")
print("}")
# Read disassembly code from stdin
for line in sys.stdin:
# let the line with the instruction pointer begin with a space
line = re.sub("^-> ", " ->", line)
if inst_re.match(line):
lines.append(line)
br_addr = get_branch_addr(line)
if br_addr:
if len(br_addr) < addr_len:
addr_len = len(br_addr)
block_starts[br_addr] = -1
else:
print_function()
lines = []
block_starts = {}
print(line, end="")
print_function()
if __name__ == "__main__":
main()
|
