This is a collection of LLDB commands to assist debugging.
本仓库用于维护作者使用的一些小众 lldb 脚本。
创建文件 ~/.lldbinit，并添加以下代码
command script import /path/to/lldb.py
| 文件 | 命令 | 参数说明 | 使用说明 |
|---|---|---|---|
| pvtable.py | vt | c++ 实例地址 | vt this vt a vt ptrA， 打印实例的虚函数列表 |
| LLVMHelper.py | llvm_raw_ostream_enable | 无 | 启动 llvm::raw_ostream::operator<< 部分断点（断点名称是llvm_raw_ostream_enable）， 会自动在触发打点时，打印当前环境变量 |
| LLVMHelper.py | llvm_raw_ostream_disable | 无 | 停用所有名称是llvm_raw_ostream_enable 的断点 |
lldb 提供了非常好用 的 Python 接口，通过这些基础接口，我们可以实现一些提高开发和调试的功能。Facebook 出品的 chisel 工具库就是其中的佼佼者。
考虑到 chisel 面向用户众多，一些小众的需求需要寻求其它解决方案。
lldb 目前缺失打印虚函数表的功能。本仓库提供了 vt this 命令，用于打印实例的虚函数表。
(lldb) vt a
0x100002048: 0x00000001000011d0 ++`A::TEST_B() at main.cpp:17
0x100002050: 0x00000001000011e0 ++`A::TEST_C() at main.cpp:26
0x100002058: 0x00000001000011f0 ++`A::TEST_A() at main.cpp:27
(lldb) vt ptrB
0x100002080: 0x00000001000011d0 ++`A::TEST_B() at main.cpp:17
0x100002088: 0x00000001000011e0 ++`A::TEST_C() at main.cpp:26
0x100002090: 0x0000000100001260 ++`B::TEST_A() at main.cpp:32
0x100002098: 0x0000000100001270 ++`B::TEST_E() at main.cpp:31
(lldb)
说明：第一列代表实例所指向的虚函数的某一项，第二列代表函数在内存中的地址，第三列代表代码函数所在 module的位置 + 函数所在源码位置
笔者在调试 llvm 源码时，经常面临在 llvm::raw_ostream::operator<<位置添加断点需求。
通常情况下，我们会通过 b llvm::raw_ostream::operator<< 命令添加断点的方式解决该诉求。
但是在解决问题的同时，该方案也带来了一些新问题。
如下所示，当参数是 (char *) 类型时，它会依次命中 2 个断点：raw_ostream &operator<<(const char *Str) 和 raw_ostream &operator<<(StringRef Str)，这会带来非常多不便。
OS << << "note: "
raw_ostream &operator<<(const char *Str) {
// Inline fast path, particularly for constant strings where a sufficiently
// smart compiler will simplify strlen.
return this->operator<<(StringRef(Str));
}
raw_ostream &operator<<(StringRef Str) {
// Inline fast path, particularly for strings with a known length.
size_t Size = Str.size();
// Make sure we can use the fast path.
if (Size > (size_t)(OutBufEnd - OutBufCur))
return write(Str.data(), Size);
if (Size) {
memcpy(OutBufCur, Str.data(), Size);
OutBufCur += Size;
}
return *this;
}实际上，上述命令会在下面 21 个函数入口设置断点（其中3个属于可以忽略的常用函数）。
152: name = 'llvm::raw_ostream::operator<<', locations = 21, resolved = 21, hit count = 0
152.1: where = dsymutil`llvm::raw_ostream::operator<<(char const*) at raw_ostream.h:196, address = 0x0000000100002a80, resolved, hit count = 0
152.2: where = dsymutil`llvm::raw_ostream::operator<<(llvm::StringRef) at raw_ostream.h:181, address = 0x0000000100002ac0, resolved, hit count = 0
152.3: where = dsymutil`llvm::raw_ostream::operator<<(char) at raw_ostream.h:160, address = 0x000000010002d460, resolved, hit count = 0
152.4: where = dsymutil`llvm::raw_ostream::operator<<(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at raw_ostream.h:203, address = 0x000000010002e650, resolved, hit count = 0
152.5: where = dsymutil`llvm::raw_ostream::operator<<(llvm::SmallVectorImpl<char> const&) at raw_ostream.h:208, address = 0x000000010002fde0, resolved, hit count = 0
152.6: where = dsymutil`llvm::raw_ostream::operator<<(unsigned int) at raw_ostream.h:218, address = 0x0000000100564aa0, resolved, hit count = 0
152.7: where = dsymutil`llvm::raw_ostream::operator<<(int) at raw_ostream.h:222, address = 0x0000000100dc4b50, resolved, hit count = 0
152.8: where = dsymutil`llvm::raw_ostream::operator<<(unsigned long) at raw_ostream.cpp:122, address = 0x000000010209c4c0, resolved, hit count = 0
152.9: where = dsymutil`llvm::raw_ostream::operator<<(long) at raw_ostream.cpp:127, address = 0x000000010209c500, resolved, hit count = 0
152.10: where = dsymutil`llvm::raw_ostream::operator<<(unsigned long long) at raw_ostream.cpp:132, address = 0x000000010209c540, resolved, hit count = 0
152.11: where = dsymutil`llvm::raw_ostream::operator<<(long long) at raw_ostream.cpp:137, address = 0x000000010209c580, resolved, hit count = 0
152.12: where = dsymutil`llvm::raw_ostream::operator<<(llvm::raw_ostream::Colors) at raw_ostream.cpp:147, address = 0x000000010209c650, resolved, hit count = 0
152.13: where = dsymutil`llvm::raw_ostream::operator<<(llvm::format_object_base const&) at raw_ostream.cpp:305, address = 0x000000010209c780, resolved, hit count = 0
152.14: where = dsymutil`llvm::raw_ostream::operator<<(unsigned char) at raw_ostream.h:167, address = 0x000000010209cc50, resolved, hit count = 0
152.15: where = dsymutil`llvm::raw_ostream::operator<<(void const*) at raw_ostream.cpp:205, address = 0x000000010209ccc0, resolved, hit count = 0
152.16: where = dsymutil`llvm::raw_ostream::operator<<(double) at raw_ostream.cpp:210, address = 0x000000010209cd20, resolved, hit count = 0
152.17: where = dsymutil`llvm::raw_ostream::operator<<(llvm::formatv_object_base const&) at raw_ostream.cpp:345, address = 0x000000010209d370, resolved, hit count = 0
152.18: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedString const&) at raw_ostream.cpp:351, address = 0x000000010209d590, resolved, hit count = 0
152.19: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedNumber const&) at raw_ostream.cpp:379, address = 0x000000010209d7e0, resolved, hit count = 0
152.20: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedBytes const&) at raw_ostream.cpp:402, address = 0x000000010209da20, resolved, hit count = 0
152.21: where = dsymutil`llvm::raw_ostream::operator<<(signed char) at raw_ostream.h:174, address = 0x0000000102fcaa80, resolved, hit count = 0
针对以上情况，本仓库提供了一份专用的命令 llvm_raw_ostream_enable，该命令会只在必要的函数位置设置断点。
如下所示。
153: name = 'llvm::raw_ostream::operator<<(llvm::raw_ostream::Colors)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
153.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::raw_ostream::Colors) at raw_ostream.cpp:147, address = 0x000000010209c650, resolved, hit count = 0
154: name = 'llvm::raw_ostream::operator<<(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
154.1: where = dsymutil`llvm::raw_ostream::operator<<(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at raw_ostream.h:203, address = 0x000000010002e650, resolved, hit count = 0
155: name = 'llvm::raw_ostream::operator<<(char)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
155.1: where = dsymutil`llvm::raw_ostream::operator<<(char) at raw_ostream.h:160, address = 0x000000010002d460, resolved, hit count = 0
156: name = 'llvm::raw_ostream::operator<<(llvm::StringRef)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
156.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::StringRef) at raw_ostream.h:181, address = 0x0000000100002ac0, resolved, hit count = 0
157: name = 'llvm::raw_ostream::operator<<(unsigned char)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
157.1: where = dsymutil`llvm::raw_ostream::operator<<(unsigned char) at raw_ostream.h:167, address = 0x000000010209cc50, resolved, hit count = 0
158: name = 'llvm::raw_ostream::operator<<(llvm::SmallVectorImpl<char> const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
158.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::SmallVectorImpl<char> const&) at raw_ostream.h:208, address = 0x000000010002fde0, resolved, hit count = 0
159: name = 'llvm::raw_ostream::operator<<(unsigned long)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
159.1: where = dsymutil`llvm::raw_ostream::operator<<(unsigned long) at raw_ostream.cpp:122, address = 0x000000010209c4c0, resolved, hit count = 0
160: name = 'llvm::raw_ostream::operator<<(long)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
160.1: where = dsymutil`llvm::raw_ostream::operator<<(long) at raw_ostream.cpp:127, address = 0x000000010209c500, resolved, hit count = 0
161: name = 'llvm::raw_ostream::operator<<(unsigned long long)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
161.1: where = dsymutil`llvm::raw_ostream::operator<<(unsigned long long) at raw_ostream.cpp:132, address = 0x000000010209c540, resolved, hit count = 0
162: name = 'llvm::raw_ostream::operator<<(long long)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
162.1: where = dsymutil`llvm::raw_ostream::operator<<(long long) at raw_ostream.cpp:137, address = 0x000000010209c580, resolved, hit count = 0
163: name = 'llvm::raw_ostream::operator<<(llvm::format_object_base const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
163.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::format_object_base const&) at raw_ostream.cpp:305, address = 0x000000010209c780, resolved, hit count = 0
164: name = 'llvm::raw_ostream::operator<<(void const*)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
164.1: where = dsymutil`llvm::raw_ostream::operator<<(void const*) at raw_ostream.cpp:205, address = 0x000000010209ccc0, resolved, hit count = 0
165: name = 'llvm::raw_ostream::operator<<(double)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
165.1: where = dsymutil`llvm::raw_ostream::operator<<(double) at raw_ostream.cpp:210, address = 0x000000010209cd20, resolved, hit count = 0
166: name = 'llvm::raw_ostream::operator<<(llvm::formatv_object_base const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
166.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::formatv_object_base const&) at raw_ostream.cpp:345, address = 0x000000010209d370, resolved, hit count = 0
167: name = 'llvm::raw_ostream::operator<<(llvm::FormattedString const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
167.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedString const&) at raw_ostream.cpp:351, address = 0x000000010209d590, resolved, hit count = 0
168: name = 'llvm::raw_ostream::operator<<(llvm::FormattedNumber const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
168.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedNumber const&) at raw_ostream.cpp:379, address = 0x000000010209d7e0, resolved, hit count = 0
169: name = 'llvm::raw_ostream::operator<<(llvm::FormattedBytes const&)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
169.1: where = dsymutil`llvm::raw_ostream::operator<<(llvm::FormattedBytes const&) at raw_ostream.cpp:402, address = 0x000000010209da20, resolved, hit count = 0
170: name = 'llvm::raw_ostream::operator<<(signed char)', locations = 1, resolved = 1, hit count = 0
Breakpoint commands:
v
Names:
llvm_raw_ostream_enable
170.1: where = dsymutil`llvm::raw_ostream::operator<<(signed char) at raw_ostream.h:174, address = 0x0000000102fcaa80, resolved, hit count = 0