软件开发过程中，调试是必不可少的环节之一，让可执行文件”明牌“执行，不会漏过每一行代码，每一个变量的信息。从而帮助开发者快速定位到问题点。
- 先看下没有调试信息的可执行文件是什么样子？
root@localhost:~/testWorkSpace/CPP11/vector$ readelf -S ./build/move
There are 30 section headers, starting at offset 0x32e0:Section Headers:[Nr] Name Type Address OffsetSize EntSize Flags Link Info Align[ 0] NULL 0000000000000000 000000000000000000000000 0000000000000000 0 0 0[ 1] .interp PROGBITS 0000000000000238 00000238000000000000001c 0000000000000000 A 0 0 1[ 2] .note.ABI-tag NOTE 0000000000000254 000002540000000000000020 0000000000000000 A 0 0 4[ 3] .note.gnu.build-i NOTE 0000000000000274 000002740000000000000024 0000000000000000 A 0 0 4[ 4] .gnu.hash GNU_HASH 0000000000000298 000002980000000000000024 0000000000000000 A 5 0 8[ 5] .dynsym DYNSYM 00000000000002c0 000002c00000000000000198 0000000000000018 A 6 1 8[ 6] .dynstr STRTAB 0000000000000458 00000458000000000000019c 0000000000000000 A 0 0 1[ 7] .gnu.version VERSYM 00000000000005f4 000005f40000000000000022 0000000000000002 A 5 0 2[ 8] .gnu.version_r VERNEED 0000000000000618 000006180000000000000080 0000000000000000 A 6 3 8[ 9] .rela.dyn RELA 0000000000000698 000006980000000000000138 0000000000000018 A 5 0 8[10] .rela.plt RELA 00000000000007d0 000007d000000000000000a8 0000000000000018 AI 5 23 8[11] .init PROGBITS 0000000000000878 000008780000000000000017 0000000000000000 AX 0 0 4[12] .plt PROGBITS 0000000000000890 000008900000000000000080 0000000000000010 AX 0 0 16[13] .plt.got PROGBITS 0000000000000910 000009100000000000000008 0000000000000008 AX 0 0 8[14] .text PROGBITS 0000000000000920 000009200000000000000512 0000000000000000 AX 0 0 16[15] .fini PROGBITS 0000000000000e34 00000e340000000000000009 0000000000000000 AX 0 0 4[16] .rodata PROGBITS 0000000000000e40 00000e400000000000000005 0000000000000000 A 0 0 4[17] .eh_frame_hdr PROGBITS 0000000000000e48 00000e4800000000000000dc 0000000000000000 A 0 0 4[18] .eh_frame PROGBITS 0000000000000f28 00000f2800000000000003c0 0000000000000000 A 0 0 8[19] .gcc_except_table PROGBITS 00000000000012e8 000012e80000000000000019 0000000000000000 A 0 0 1[20] .init_array INIT_ARRAY 0000000000201d50 00001d500000000000000010 0000000000000008 WA 0 0 8[21] .fini_array FINI_ARRAY 0000000000201d60 00001d600000000000000008 0000000000000008 WA 0 0 8[22] .dynamic DYNAMIC 0000000000201d68 00001d680000000000000210 0000000000000010 WA 6 0 8[23] .got PROGBITS 0000000000201f78 00001f780000000000000088 0000000000000008 WA 0 0 8[24] .data PROGBITS 0000000000202000 000020000000000000000018 0000000000000000 WA 0 0 8[25] .bss NOBITS 0000000000202020 000020180000000000000118 0000000000000000 WA 0 0 32[26] .comment PROGBITS 0000000000000000 000020180000000000000029 0000000000000001 MS 0 0 1[27] .symtab SYMTAB 0000000000000000 000020480000000000000a08 0000000000000018 28 48 8[28] .strtab STRTAB 0000000000000000 00002a50000000000000077e 0000000000000000 0 0 1[29] .shstrtab STRTAB 0000000000000000 000031ce0000000000000110 0000000000000000 0 0 1
Key to Flags:W (write), A (alloc), X (execute), M (merge), S (strings), I (info),L (link order), O (extra OS processing required), G (group), T (TLS),C (compressed), x (unknown), o (OS specific), E (exclude),l (large), p (processor specific)
使用gdb工具调试运行上述文件，只能看到一行行指令，是没有代码的。
- 再看下带有调试信息的可执行文件
root@localhost:~/testWorkSpace/CPP11/vector$ readelf -S ./build/move
There are 36 section headers, starting at offset 0xb8c8:Section Headers:[Nr] Name Type Address OffsetSize EntSize Flags Link Info Align[ 0] NULL 0000000000000000 000000000000000000000000 0000000000000000 0 0 0[ 1] .interp PROGBITS 0000000000000238 00000238000000000000001c 0000000000000000 A 0 0 1[ 2] .note.ABI-tag NOTE 0000000000000254 000002540000000000000020 0000000000000000 A 0 0 4[ 3] .note.gnu.build-i NOTE 0000000000000274 000002740000000000000024 0000000000000000 A 0 0 4[ 4] .gnu.hash GNU_HASH 0000000000000298 000002980000000000000024 0000000000000000 A 5 0 8[ 5] .dynsym DYNSYM 00000000000002c0 000002c00000000000000198 0000000000000018 A 6 1 8[ 6] .dynstr STRTAB 0000000000000458 00000458000000000000019c 0000000000000000 A 0 0 1[ 7] .gnu.version VERSYM 00000000000005f4 000005f40000000000000022 0000000000000002 A 5 0 2[ 8] .gnu.version_r VERNEED 0000000000000618 000006180000000000000080 0000000000000000 A 6 3 8[ 9] .rela.dyn RELA 0000000000000698 000006980000000000000138 0000000000000018 A 5 0 8[10] .rela.plt RELA 00000000000007d0 000007d000000000000000a8 0000000000000018 AI 5 23 8[11] .init PROGBITS 0000000000000878 000008780000000000000017 0000000000000000 AX 0 0 4[12] .plt PROGBITS 0000000000000890 000008900000000000000080 0000000000000010 AX 0 0 16[13] .plt.got PROGBITS 0000000000000910 000009100000000000000008 0000000000000008 AX 0 0 8[14] .text PROGBITS 0000000000000920 000009200000000000000512 0000000000000000 AX 0 0 16[15] .fini PROGBITS 0000000000000e34 00000e340000000000000009 0000000000000000 AX 0 0 4[16] .rodata PROGBITS 0000000000000e40 00000e400000000000000005 0000000000000000 A 0 0 4[17] .eh_frame_hdr PROGBITS 0000000000000e48 00000e4800000000000000dc 0000000000000000 A 0 0 4[18] .eh_frame PROGBITS 0000000000000f28 00000f2800000000000003c0 0000000000000000 A 0 0 8[19] .gcc_except_table PROGBITS 00000000000012e8 000012e80000000000000019 0000000000000000 A 0 0 1[20] .init_array INIT_ARRAY 0000000000201d50 00001d500000000000000010 0000000000000008 WA 0 0 8[21] .fini_array FINI_ARRAY 0000000000201d60 00001d600000000000000008 0000000000000008 WA 0 0 8[22] .dynamic DYNAMIC 0000000000201d68 00001d680000000000000210 0000000000000010 WA 6 0 8[23] .got PROGBITS 0000000000201f78 00001f780000000000000088 0000000000000008 WA 0 0 8[24] .data PROGBITS 0000000000202000 000020000000000000000018 0000000000000000 WA 0 0 8[25] .bss NOBITS 0000000000202020 000020180000000000000118 0000000000000000 WA 0 0 32[26] .comment PROGBITS 0000000000000000 000020180000000000000029 0000000000000001 MS 0 0 1[27] .debug_aranges PROGBITS 0000000000000000 000020410000000000000150 0000000000000000 0 0 1[28] .debug_info PROGBITS 0000000000000000 000021910000000000003fe5 0000000000000000 0 0 1[29] .debug_abbrev PROGBITS 0000000000000000 000061760000000000000755 0000000000000000 0 0 1[30] .debug_line PROGBITS 0000000000000000 000068cb0000000000000623 0000000000000000 0 0 1[31] .debug_str PROGBITS 0000000000000000 00006eee000000000000351d 0000000000000001 MS 0 0 1[32] .debug_ranges PROGBITS 0000000000000000 0000a40b0000000000000140 0000000000000000 0 0 1[33] .symtab SYMTAB 0000000000000000 0000a5500000000000000a98 0000000000000018 34 54 8[34] .strtab STRTAB 0000000000000000 0000afe8000000000000077e 0000000000000000 0 0 1[35] .shstrtab STRTAB 0000000000000000 0000b766000000000000015e 0000000000000000 0 0 1
Key to Flags:W (write), A (alloc), X (execute), M (merge), S (strings), I (info),L (link order), O (extra OS processing required), G (group), T (TLS),C (compressed), x (unknown), o (OS specific), E (exclude),l (large), p (processor specific)
好像没啥区别，过滤下看看
root@localhost:~/testWorkSpace/CPP11/vector$ readelf -S ./build/move | grep debug[27] .debug_aranges PROGBITS 0000000000000000 00002041[28] .debug_info PROGBITS 0000000000000000 00002191[29] .debug_abbrev PROGBITS 0000000000000000 00006176[30] .debug_line PROGBITS 0000000000000000 000068cb[31] .debug_str PROGBITS 0000000000000000 00006eee[32] .debug_ranges PROGBITS 0000000000000000 0000a40b
可执行文件中，正是多加了这些字段信息，才让GDB工具可以“明牌”运行。
- 看到了目标效果，绕回本文主题，CMake工具如何生成带有调试信息的执行文件呢？
在CMake.txt文件中，设置如下编译参数就可以了（适用于CMake 3.14.7 版本）
add_definitions("-Wall -g")
set(CMAKE_BUILD_TYPE "Debug")
)
)
