pgoodman

VTable Notes on Multiple Inheritance in GCC C++ Compiler v4.0.1

http://www.cse.wustl.edu/~mdeters/seminar/fall2005/mi.html#basics

The Basics: Single Inheritance

As we discussed in class, single inheritance leads to an object layoutwith base class data laid out before derived class data. So if classes A and B are defined as:

pgoodman

# Copyright 2024, Peter Goodman. All rights reserved.

"""
This program approximately groups functions by their types, and then prints
out the grouped functions.

XREF: https://x.com/eatonphil/status/1821573274582823247
"""

import argparse

pgoodman

+- Grammar ---------------+    +-----------------------------------------------------+
|                         |    | Production              | Nullable | FIRST | FOLLOW |
| S -> S S                |    |-------------------------+----------+-------+--------|
| S -> if E then S else S |    | S' -> S $               | False    | exit  |        |
| S -> if E then S        |    |                         |          | if    |        |
| S -> exit when E        |    |-------------------------+----------+-------+--------|
+-------------------------+    | S -> S S                | False    | exit  | $      |
                               | S -> if E then S else S |          | if    | exit   |
                               | S -> if E then S        |          |       | if     |
                               | S -> exit when E        |          |       | else   |

pgoodman

// Copyright 2020 Peter Goodman, all rights reserved.

#include <cassert>
#include <cstdint>
#include <cstddef>
#include <iostream>
#include <type_traits>
#include <vector>

template<typename IntegralType_, unsigned kNumBits_, unsigned kShift_>

pgoodman

On macOS

export CFLAGS="-fsanitize=address -ffunction-sections -fdata-sections -Wl,-dead_strip -Wl,-undefined,dynamic_lookup -Wno-unused-command-line-argument"
export CXXFLAGS="-fsanitize=address -ffunction-sections -fdata-sections -Wl,-dead_strip -Wl,-undefined,dynamic_lookup -Wno-unused-command-line-argument"

On Linux

export CFLAGS="-fsanitize=address -ffunction-sections -fdata-sections -Wl,--gc-sections -Wl,--allow-multiple-definition"
export CXXFLAGS="-fsanitize=address -ffunction-sections -fdata-sections -Wl,--gc-sections -Wl,--allow-multiple-definition"

pgoodman

/path/to/remill-build/tools/anvill/anvill-decompile-json-9.0 --spec /tmp/slice.json --ir_out /dev/stderr

pgoodman

clang --target=armv8-pc-linux-gnu -m64 -c /tmp/test.c -o /tmp/test.o

pgoodman

Instructions for a full build of Remill and its depedencies.

Clone cxx-common

cd ~/src
git clone [email protected]:trailofbits/cxx-common.git

Repository path

pgoodman

target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu-elf"

%struct.Memory = type opaque
%struct.State = type { %struct.ArchState, [32 x %union.VectorReg], %struct.ArithFlags, %union.anon, %struct.Segments, %struct.AddressSpace, %struct.GPR, %struct.X87Stack, %struct.MMX, %struct.FPUStatusFlags, %union.anon, %union.FPU, %struct.SegmentCaches }
%struct.ArchState = type { i32, i32, %union.anon }
%union.VectorReg = type { %union.vec512_t }
%union.vec512_t = type { %struct.uint64v8_t }
%struct.uint64v8_t = type { [8 x i64] }
%struct.ArithFlags = type { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8 }

pgoodman

0:  89 f8                   mov    eax,edi
2:  0f b7 4c 24 18          movzx  ecx,WORD PTR [rsp+0x18]
7:  81 f9 00 80 00 00       cmp    ecx,0x8000
d:  0f 95 c1                setne  cl
10: d3 e0                   shl    eax,cl
12: c3                      ret