gcc与g++的常用编译选项

gcc与g++的常用编译选项

(Owed by: 春夜喜雨 http://blog.csdn.net/chunyexiyu)
参考：https://man7.org/linux/man-pages/man1/g++.1.html
参考：https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/Option-Summary.html#Option-Summary
参考：https://blog.csdn.net/ivan240/article/details/5363395
参考：https://blog.csdn.net/sinat_36219858/article/details/80348889

引言

下面对gcc和g++的常用项进行一些罗列，方便需要时快速查找使用。

gcc命令：

    gcc [-c|-S|-E] [-std=standard]
           [-g] [-pg] [-Olevel]
           [-Wwarn...] [-Wpedantic]
           [-Idir...] [-Ldir...]
           [-Dmacro[=defn]...] [-Umacro]
           [-foption...] [-mmachine-option...]
           [-o outfile] [@file] infile...

g++和gcc大多选型都相同。

帮助与版本：

–help 显示gcc帮助信息 Display this information
–version 显示gcc版本 Display compiler version information
–help={common|optimizers|params|target|warnings|[^]{joined|separate|undocumented}}[,…]
显示特定类型的参数选项信息 Display specific types of command line options
(Use ‘-v --help’ to display command line options of sub-processes)

编译文件选项：-c -S -E -o file -g

-g 带调试信息，gdb下可以看到源码 Produce debugging information in the operating system’s native format (stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging information.
-c 编译和汇编，但不链接，通常用于输出.o文件 Compile and assemble, but do not link
-S 仅编译，不汇编和链接，通常用于输出汇编文件 Compile only; do not assemble or link
-E 仅预处理，不编译、汇编和链接，通常用于查看预编译后的文件内容 Preprocess only; do not compile, assemble or link
-o 指定输出文件 Place the output into
-v 启用冗余输出 Enable verbose output
-v 打印编译使用命令出来 Print (on standard error output) the commands executed to run the stages of compilation.
-D macro[=defn] 定义宏信息 Predefine name as a macro, default with definition 1.
-U name 取消宏定义信息 Cancel any previous definition of name, either built in or provided with a -D option.
-l library 链接时查找引用该库文件 Search the library named library when linking.
-I DIRECTORY 添加头文件查找路径 Add DIRECTORY to header file search path
-L DIRECTORY, --library-path DIRECTORY 添加库查找路径 Add DIRECTORY to library search path
-B 添加编译查找路径 Add to the compiler’s search paths
-std= 指定源码使用的gcc库版本，例如-std=c++11指定使用c++11语法和库 Assume that the input sources are for
-shared 创建共享库，该种类型库可以不用链接其它库，使用该库时再连接 Create a shared library
-pipe 使用管道替代中间文件产生，该种方式可以减少中间文件产生 Use pipes rather than intermediate files

编译优化参数：-O -O0 -O1 -O2 -O3 -Os -Ofast -Og

-O 设置编译优化级别，常见的-O0(不启用优化)，-O2/-O3(全局优化) Set optimization level to
-Os 启用优化：空间占用优先于速度 Optimize for space rather than speed
-Ofast 启用优化：速度优先，忽略规则遵从性 Optimize for speed disregarding exact standards compliance
-Og 启用优化：不影响调试的优化 Optimize for debugging experience rather than speed or size
-Werror 把所有告警作为错误 Treat all warnings as errors
-Werror= 指定特定告警作为错误 Treat specified warning as error
-Wshadow 当local变量遮盖住另一个时告警 Warn when one local variable shadows another
-Wunused-variable 变量未使用时告警 Warn when a variable is unused
-w 不输出告警 Suppress warnings

另外一些参数：

-pie 创建一个位置无关的执行文件，让程序能装载在随机，放之缓冲区溢出攻击等。 Create a position independent executable
-print-search-dirs 打印编译查找路径 Display the directories in the compiler’s search path
-fpic Generate position-independent code if possible (small mode)
-fpie Generate position-independent code for executables if possible (small mode)

例子：sqlite编译

来看一看sqlite的编译选项：
gcc -c sqlite3.c -fPIC -lpthread -ldl -o sqlite3.o
ar -r ./lib/libsqlite3.a sqlite3.o

1- 首先编译sqlite3.c生成sqlite3.o
2- 然后使用ar把sqlite3.o打包到静态库包libsqlite3.a

附录：g++的help显示

$ g++ --help
Usage: g++ [options] file...
Options:
  -pass-exit-codes         Exit with highest error code from a phase
  --help                   Display this information
  --target-help            Display target specific command line options
  --help={common|optimizers|params|target|warnings|[^]{joined|separate|undocumented}}[,...]
                           Display specific types of command line options
  (Use '-v --help' to display command line options of sub-processes)
  --version                Display compiler version information
  -dumpspecs               Display all of the built in spec strings
  -dumpversion             Display the version of the compiler
  -dumpmachine             Display the compiler's target processor
  -print-search-dirs       Display the directories in the compiler's search path
  -print-libgcc-file-name  Display the name of the compiler's companion library
  -print-file-name=   Display the full path to library 
  -print-prog-name=  Display the full path to compiler component 
  -print-multiarch         Display the target's normalized GNU triplet, used as
                           a component in the library path
  -print-multi-directory   Display the root directory for versions of libgcc
  -print-multi-lib         Display the mapping between command line options and
                           multiple library search directories
  -print-multi-os-directory Display the relative path to OS libraries
  -print-sysroot           Display the target libraries directory
  -print-sysroot-headers-suffix Display the sysroot suffix used to find headers
  -Wa,            Pass comma-separated  on to the assembler
  -Wp,            Pass comma-separated  on to the preprocessor
  -Wl,            Pass comma-separated  on to the linker
  -Xassembler         Pass  on to the assembler
  -Xpreprocessor      Pass  on to the preprocessor
  -Xlinker            Pass  on to the linker
  -save-temps              Do not delete intermediate files
  -save-temps=        Do not delete intermediate files
  -no-canonical-prefixes   Do not canonicalize paths when building relative
                           prefixes to other gcc components
  -pipe                    Use pipes rather than intermediate files
  -time                    Time the execution of each subprocess
  -specs=            Override built-in specs with the contents of 
  -std=          Assume that the input sources are for 
  --sysroot=    Use  as the root directory for headers
                           and libraries
  -B            Add  to the compiler's search paths
  -v                       Display the programs invoked by the compiler
  -###                     Like -v but options quoted and commands not executed
  -E                       Preprocess only; do not compile, assemble or link
  -S                       Compile only; do not assemble or link
  -c                       Compile and assemble, but do not link
  -o                 Place the output into 
  -pie                     Create a position independent executable
  -shared                  Create a shared library
  -x             Specify the language of the following input files
                           Permissible languages include: c c++ assembler none
                           'none' means revert to the default behavior of
                           guessing the language based on the file's extension

Options starting with -g, -f, -m, -O, -W, or --param are automatically
 passed on to the various sub-processes invoked by g++.  In order to pass
 other options on to these processes the -W options must be used.

For bug reporting instructions, please see:
.

(Owed by: 春夜喜雨
http://blog.csdn.net/chunyexiyu)