GCC：march如何与mtune不同？ [英] GCC: how is march different from mtune?

问题描述

之间有什么区别？

march 和 -mtune ？

何时使用 -march ，与两者？是否可以只是 -mtune ？

谢谢。

解决方案

如果使用 -march ，GCC可以自由生成在指定CPU上工作的指令， （通常）较早的CPU。如果使用 -mtune ，那么编译器将生成可以在其中任何一个上工作的代码，但是将有利于在指定的CPU上运行速度最快的指令序列。

I tried to scrub the GCC man page for this, but still don't get it, really.

What's the difference between -march and -mtune ?

When does one use just -march, vs. both? Is it ever possible to just -mtune ?

Thanks.

解决方案

If you use -march then GCC will be free to generate instructions that work on the specified CPU, but not on (typically) earlier CPUs in the architecture family. If you use -mtune, then the compiler will generate code that works on any of them, but will favour instruction sequences that run fastest on the specific CPU you indicated.

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