现代C ++编译器可以在cpp文件中定义内联函数 [英] Can modern C++ compilers inline functions that are defined in a cpp file

问题描述

我知道关键字 inline 具有有用的属性。用于将模板特殊化保留在头文件中。
另一方面，我经常读到 inline 几乎没有用作编译器实际内联函数的提示。
此外，关键字不能在cpp文件中使用，因为编译器只要在调用 inline 关键字时检查标记的函数。

I am aware that the keyword inline has useful properties e.g. for keeping template specializations inside a header file. On the other hand I have often read that inline is almost useless as hint for the compiler to actually inline functions. Further the keyword cannot be used inside a cpp file since the compiler wants to inspect functions marked with the inline keyword whenever they are called.

因此，我对现代编译器的自动内联功能（即gcc 4.43）有点困惑。当我在cpp中定义一个函数时，无论如何，如果它认为内联对函数有意义，或者我是否抢夺了一些优化功能，编译器是否可以内联？

Hence I am a little confused about the "automatic" inlining capabilities of modern compilers (namely gcc 4.43). When I define a function inside a cpp, can the compiler inline it anyway if it deems that inlining makes sense for the function or do I rob him of some optimization capabilities ? (Which would be fine for the majority of functions, but important to know for small ones called very often)

推荐答案

这取决于具体的功能（这对于大多数功能来说都是很好的，你的编译标志。使用 -combine 和 -fwhole-program ， gcc do函数内联跨cpp边界。如果你编译成多个目标文件，我不知道链接器会做多少。

This depends on your compilation flags. With -combine and -fwhole-program, gcc will do function inlining across cpp boundaries. I'm not sure how much the linker will do if you compile into multiple object files.

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