g++ 参数

gnu++11 = c++11 + GNU extension

• g is a flag that tells the compiler to include debugging information in the output.
• 02 Level 2 optimization
• fopenmp 多线程优化

OpenMP, a parallel programming model for multi-platform shared-memory multi-processing in C, C++, and Fortran.

• shared :告诉编译器生成一个动态链接库（g++ 下使用 shared 一定要使用 fPIC）
• fPIC Position Independent Code
• fstack-protector-strong

A security feature that add extra code to check for buffer overflows, such as stack smashing attacks.

• fpermissive

downgrade certain diagnostics about nonconformant code from errors to warnings.

• fdebug-prefix-map: replacing the build paths with relative paths
• Werror=format-security turn format (printf scanf .etc) vulnerabilities into errors.
• Wformat check the format strings in printf-style functions and warn about any problems that it finds.
• Wdate-time is a flag that warns if the DATE, TIME, or TIMESTAMP macros are used. Because these macros expand to the build date and time, their use can make the build non-deterministic.
• D_FORTIFY_SOURCE=2

_FORTIFY_SOURCE is a macro that, when set to 1 or 2, enables a set of macros in the C library that replace unsafe functions (like strcpy and sprintf) with safer versions that include additional checks.

• D_SIMU

a flag used by the GCC compiler to define a preprocessor macro named _SIMU. The -D flag is followed by the name of the macro to be defined. When this flag is used, the preprocessor will replace all instances of _SIMU in the code with 1