C语言 “inline __attribute__((always_inline))”在函数中是什么意思？
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what “inline __attribute__((always_inline))” means in the function?
提问by developer
I have found the following function definition :
我找到了以下函数定义：
static inline __attribute__((always_inline)) int fn(const char *s)
{
return (!s || (*s == '##代码##'));
}
And I want to know the meaning of inline __attribute__((always_inline))?
我想知道inline __attribute__((always_inline))?
回答by Maxim Egorushkin
The often referred gcc documentation for always_inlineis inaccurate.
经常提到的 gcc 文档always_inline是不准确的。
This attribute makes the compiler ignore -fno-inline(this is what the documentation says) and the inlining limitshence inlining the function anyway. Also, it inlines functions with allocacalls, which inlinekeyword never does.
这个属性使编译器忽略-fno-inline（这是文档所说的）和内联限制，因此无论如何内联函数。此外，它使用alloca调用内联函数，而inline关键字从不这样做。
An interesting bechmark: always_inlineperformance.
一个有趣的基准：always_inline性能。
回答by Manu343726
It forces the compiler to inline the function even if optimizations are disabled. Check this documentationfor more information.
即使优化被禁用，它也会强制编译器内联函数。查看此文档以获取更多信息。
