busybox中FAST_FUNC

最新推荐文章于 2024-10-11 17:23:42 发布

duanjianyuooo

最新推荐文章于 2024-10-11 17:23:42 发布

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分类专栏： busybox

本文链接：https://blog.youkuaiyun.com/duanjianyuooo/article/details/10941177

busybox的FAST_FUNC是一个可能使函数调用更快、更小的修饰符，特别是在非静态内部函数上。当使用GCC 3.0及更高版本且目标为i386架构时，FAST_FUNC会使用stdcall属性，让被调用者负责从堆栈中弹出参数。否则，FAST_FUNC不定义。此功能在某些架构下可以优化参数传递方式，减少堆栈使用。

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busybox/src/include/platform.h

/* FAST_FUNC is a qualifier which (possibly) makes function call faster
 * and/or smaller by using modified ABI. It is usually only needed
 * on non-static, busybox internal functions. Recent versions of gcc
 * optimize statics automatically. FAST_FUNC on static is required
 * only if you need to match a function pointer's type */
#if __GNUC_PREREQ(3,0) && defined(i386) /* || defined(__x86_64__)? */
/* stdcall makes callee to pop arguments from stack, not caller */
# define FAST_FUNC __attribute__((regparm(3),stdcall))
/* #elif ... - add your favorite arch today! */
#else
#