一些GCC的宏

最新推荐文章于 2024-04-03 11:28:40 发布

原创最新推荐文章于 2024-04-03 11:28:40 发布 · 273 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#gcc #function #compiler #integer

GCC 专栏收录该内容

0 篇文章

订阅专栏

本文介绍GCC内置函数__builtin_constant_p的使用方法,该函数用于判断表达式的值是否为编译时常量,从而帮助进行常量折叠优化.同时简述了__ARMEB__宏的定义方式.

1. — Built-in Function: int __builtin_constant_p (exp)
You can use the built-in function __builtin_constant_p to determine if a value is known to be constant at compile-time and hence that GCC can perform constant-folding on expressions involving that value. The argument of the function is the value to test. The function returns the integer 1 if the argument is known to be a compile-time constant and 0 if it is not known to be a compile-time constant. A return of 0 does not indicate that the value is not a constant, but merely that GCC cannot prove it is a constant with the specified value of the -O option.

2. __ARMEB__:

if defined big endian, it's defined by the compiler when it is invoked with -EB (for big-endian).