'Lower the current function\'s body, and return the entry block.'

def lower_function_body(self):

    for offset in self.blocks:
        bname = ('B%s' % offset)
        self.blkmap[offset] = self.function.append_basic_block(bname)
    self.pre_lower()
    entry_block_tail = self.builder.basic_block
    self.debug_print('#    function    begin:    {0}'.format(self.fndesc.unique_name))
    for (offset, block) in self.blocks.items():
        bb = self.blkmap[offset]
        self.builder.position_at_end(bb)
        self.lower_block(block)
    self.post_lower()
    return entry_block_tail
