（如何）我可以内联特定函数调用？ [英] (How) Can I inline a particular function call?

问题描述

让我们说，我有一个被调用在一个程序的多个部分功能。我们也可以说，我要的职能，这是在code的极端性能敏感的部分特定的呼叫（例如，一个循环，迭代千万次，其中每个微秒计数）。有没有一种方法，我可以强制编译器（ GCC 在我的情况），内联单一，特别是函数调用，无需内嵌其他人呢？

Let's say that I have a function that gets called in multiple parts of a program. Let's also say that I have a particular call to that function that is in an extremely performance-sensitive section of code (e.g., a loop that iterates tens of millions of times and where each microsecond counts). Is there a way that I can force the complier (gcc in my case) to inline that single, particular function call, without inlining the others?

编辑：让我做这个完全清楚：这个问题不是的强制的海湾合作​​委员会（或任何其他编译器）内联函数所有的呼叫;相反，它是关于请求编译器内嵌一个的特定呼叫的一个函数。

Let me make this completely clear: this question is NOT about forcing gcc (or any other compiler) to inline all calls to a function; rather, it it about requesting that the compiler inline a particular call to a function.

推荐答案

在C（而不是C ++）有表明函数应该内联的标准方法。这是只有特定厂商的扩展。

In C (as opposed to C++) there's no standard way to suggest that a function should be inlined. It's only vender-specific extensions.

不过你指定它，因为据我所知，编译器将总是尝试内联每个实例，因此使用该功能只有一次：

However you specify it, as far as I know the compiler will always try to inline every instance, so use that function only once:

原文：

   int MyFunc()  { /* do stuff */  }

更改为：

   inline int MyFunc_inlined()  { /* do stuff */  }

   int MyFunc()  { return MyFunc_inlined(); }

现在，在您希望它内联，想去的地方使用 MyFunc_inlined（）

Now, in theplaces where you want it inlined, use MyFunc_inlined()

请注意：在上面的内联的关键字只是出于某种语法GCC使用强制的内联的占位符。如果H2CO3的删除答案是信任的，这将是：

Note: "inline" keyword in the above is just a placeholder for whatever syntax gcc uses to force an inlining. If H2CO3's deleted answer is to be trusted, that would be:

static inline __attribute__((always_inline)) int MyFunc_inlined()  { /* do stuff */  }

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