Say I have an arbitrary address and I want to find out which basic block (i.e. area_t structure) corresponds to it. How would I do that?

Edit: more specifically, I want to know the beginning / end of the basic block to which a given address belongs.


2 Answers 2


I put this together quickly in the File > Python command... dialog:

tgtEA = idaapi.askaddr(0, "Enter target address")
if tgtEA is None:

f = idaapi.get_func(tgtEA)
if not f:
  print "No function at 0x%x" % (tgtEA)

fc = idaapi.FlowChart(f)

for block in fc:
  if block.startEA <= tgtEA:
    if block.endEA > tgtEA:
      print "0x%x is part of block [0x%x - 0x%x)" % (tgtEA, block.startEA, block.endEA)

Keep in mind that IDA's basic block addresses are "startEA inclusive, endEA exclusive".


As suggested by DCoder, I use the following helper class to efficiently resolve addresses to basic blocks:

# Wrapper to operate on sorted basic blocks.
class BBWrapper(object):
  def __init__(self, ea, bb):
    self.ea_ = ea
    self.bb_ = bb

  def get_bb(self):
    return self.bb_

  def __lt__(self, other):
    return self.ea_ < other.ea_

# Creates a basic block cache for all basic blocks in the given function.
class BBCache(object):
  def __init__(self, f):
    self.bb_cache_ = []
    for bb in idaapi.FlowChart(f):
      self.bb_cache_.append(BBWrapper(bb.startEA, bb))
    self.bb_cache_ = sorted(self.bb_cache_)

  def find_block(self, ea):
    i = bisect_right(self.bb_cache_, BBWrapper(ea, None))
    if i:
      return self.bb_cache_[i-1].get_bb()
      return None

It can be used like this:

bb_cache = BBCache(idaapi.get_func(here()))
found = bb_cache.find_block(here())
if found:
  print "found: %X - %X" % (found.startEA, found.endEA)
  print "No basic block found that contains %X" % here()

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