CMake_02_如何编译可调试文件
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 Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .interp PROGBITS 0000000000000238 00000238
000000000000001c 0000000000000000 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000000254 00000254
0000000000000020 0000000000000000 A 0 0 4
[ 3] .note.gnu.build-i NOTE 0000000000000274 00000274
0000000000000024 0000000000000000 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000000298 00000298
0000000000000024 0000000000000000 A 5 0 8
[ 5] .dynsym DYNSYM 00000000000002c0 000002c0
0000000000000198 0000000000000018 A 6 1 8
[ 6] .dynstr STRTAB 0000000000000458 00000458
000000000000019c 0000000000000000 A 0 0 1
[ 7] .gnu.version VERSYM 00000000000005f4 000005f4
0000000000000022 0000000000000002 A 5 0 2
[ 8] .gnu.version_r VERNEED 0000000000000618 00000618
0000000000000080 0000000000000000 A 6 3 8
[ 9] .rela.dyn RELA 0000000000000698 00000698
0000000000000138 0000000000000018 A 5 0 8
[10] .rela.plt RELA 00000000000007d0 000007d0
00000000000000a8 0000000000000018 AI 5 23 8
[11] .init PROGBITS 0000000000000878 00000878
0000000000000017 0000000000000000 AX 0 0 4
[12] .plt PROGBITS 0000000000000890 00000890
0000000000000080 0000000000000010 AX 0 0 16
[13] .plt.got PROGBITS 0000000000000910 00000910
0000000000000008 0000000000000008 AX 0 0 8
[14] .text PROGBITS 0000000000000920 00000920
0000000000000512 0000000000000000 AX 0 0 16
[15] .fini PROGBITS 0000000000000e34 00000e34
0000000000000009 0000000000000000 AX 0 0 4
[16] .rodata PROGBITS 0000000000000e40 00000e40
0000000000000005 0000000000000000 A 0 0 4
[17] .eh_frame_hdr PROGBITS 0000000000000e48 00000e48
00000000000000dc 0000000000000000 A 0 0 4
[18] .eh_frame PROGBITS 0000000000000f28 00000f28
00000000000003c0 0000000000000000 A 0 0 8
[19] .gcc_except_table PROGBITS 00000000000012e8 000012e8
0000000000000019 0000000000000000 A 0 0 1
[20] .init_array INIT_ARRAY 0000000000201d50 00001d50
0000000000000010 0000000000000008 WA 0 0 8
[21] .fini_array FINI_ARRAY 0000000000201d60 00001d60
0000000000000008 0000000000000008 WA 0 0 8
[22] .dynamic DYNAMIC 0000000000201d68 00001d68
0000000000000210 0000000000000010 WA 6 0 8
[23] .got PROGBITS 0000000000201f78 00001f78
0000000000000088 0000000000000008 WA 0 0 8
[24] .data PROGBITS 0000000000202000 00002000
0000000000000018 0000000000000000 WA 0 0 8
[25] .bss NOBITS 0000000000202020 00002018
0000000000000118 0000000000000000 WA 0 0 32
[26] .comment PROGBITS 0000000000000000 00002018
0000000000000029 0000000000000001 MS 0 0 1
[27] .symtab SYMTAB 0000000000000000 00002048
0000000000000a08 0000000000000018 28 48 8
[28] .strtab STRTAB 0000000000000000 00002a50
000000000000077e 0000000000000000 0 0 1
[29] .shstrtab STRTAB 0000000000000000 000031ce
0000000000000110 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 Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .interp PROGBITS 0000000000000238 00000238
000000000000001c 0000000000000000 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000000254 00000254
0000000000000020 0000000000000000 A 0 0 4
[ 3] .note.gnu.build-i NOTE 0000000000000274 00000274
0000000000000024 0000000000000000 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000000298 00000298
0000000000000024 0000000000000000 A 5 0 8
[ 5] .dynsym DYNSYM 00000000000002c0 000002c0
0000000000000198 0000000000000018 A 6 1 8
[ 6] .dynstr STRTAB 0000000000000458 00000458
000000000000019c 0000000000000000 A 0 0 1
[ 7] .gnu.version VERSYM 00000000000005f4 000005f4
0000000000000022 0000000000000002 A 5 0 2
[ 8] .gnu.version_r VERNEED 0000000000000618 00000618
0000000000000080 0000000000000000 A 6 3 8
[ 9] .rela.dyn RELA 0000000000000698 00000698
0000000000000138 0000000000000018 A 5 0 8
[10] .rela.plt RELA 00000000000007d0 000007d0
00000000000000a8 0000000000000018 AI 5 23 8
[11] .init PROGBITS 0000000000000878 00000878
0000000000000017 0000000000000000 AX 0 0 4
[12] .plt PROGBITS 0000000000000890 00000890
0000000000000080 0000000000000010 AX 0 0 16
[13] .plt.got PROGBITS 0000000000000910 00000910
0000000000000008 0000000000000008 AX 0 0 8
[14] .text PROGBITS 0000000000000920 00000920
0000000000000512 0000000000000000 AX 0 0 16
[15] .fini PROGBITS 0000000000000e34 00000e34
0000000000000009 0000000000000000 AX 0 0 4
[16] .rodata PROGBITS 0000000000000e40 00000e40
0000000000000005 0000000000000000 A 0 0 4
[17] .eh_frame_hdr PROGBITS 0000000000000e48 00000e48
00000000000000dc 0000000000000000 A 0 0 4
[18] .eh_frame PROGBITS 0000000000000f28 00000f28
00000000000003c0 0000000000000000 A 0 0 8
[19] .gcc_except_table PROGBITS 00000000000012e8 000012e8
0000000000000019 0000000000000000 A 0 0 1
[20] .init_array INIT_ARRAY 0000000000201d50 00001d50
0000000000000010 0000000000000008 WA 0 0 8
[21] .fini_array FINI_ARRAY 0000000000201d60 00001d60
0000000000000008 0000000000000008 WA 0 0 8
[22] .dynamic DYNAMIC 0000000000201d68 00001d68
0000000000000210 0000000000000010 WA 6 0 8
[23] .got PROGBITS 0000000000201f78 00001f78
0000000000000088 0000000000000008 WA 0 0 8
[24] .data PROGBITS 0000000000202000 00002000
0000000000000018 0000000000000000 WA 0 0 8
[25] .bss NOBITS 0000000000202020 00002018
0000000000000118 0000000000000000 WA 0 0 32
[26] .comment PROGBITS 0000000000000000 00002018
0000000000000029 0000000000000001 MS 0 0 1
[27] .debug_aranges PROGBITS 0000000000000000 00002041
0000000000000150 0000000000000000 0 0 1
[28] .debug_info PROGBITS 0000000000000000 00002191
0000000000003fe5 0000000000000000 0 0 1
[29] .debug_abbrev PROGBITS 0000000000000000 00006176
0000000000000755 0000000000000000 0 0 1
[30] .debug_line PROGBITS 0000000000000000 000068cb
0000000000000623 0000000000000000 0 0 1
[31] .debug_str PROGBITS 0000000000000000 00006eee
000000000000351d 0000000000000001 MS 0 0 1
[32] .debug_ranges PROGBITS 0000000000000000 0000a40b
0000000000000140 0000000000000000 0 0 1
[33] .symtab SYMTAB 0000000000000000 0000a550
0000000000000a98 0000000000000018 34 54 8
[34] .strtab STRTAB 0000000000000000 0000afe8
000000000000077e 0000000000000000 0 0 1
[35] .shstrtab STRTAB 0000000000000000 0000b766
000000000000015e 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")