如何为英特尔和 arm 架构构建具有不同代码的 osx 通用二进制文件

Question

My goal is to create a universal/fat binary of my app, my understanding is that means xcode will create an intel/x86_64 build and an M1/arm build and package them together. My code uses intel intrinsics which I can replace with NEON in the arm build but to do so I need a way to create a conditional block at compile time for the target architecture. Is this possible? How can I achieve this?

What I've tried so far:

#include "TargetConditionals.h"
#if defined TARGET_CPU_ARM64
    #include <sse2neon.h> //NEON intristics
#endif
#if defined TARGET_CPU_X86_64
    #include <emmintrin.h> //Intel intristics
#endif

When this was used Xcode tried to compile the arm code into the x86_64 build which failed. I suppose both targets are defined at compile time but Xcode builds intel then arm objects separately so there must be a way for it to define which is which that I can use.

Answer 1

I found the solution, with help from the comments (thank you!)

I was misusing the definitions, all these are defined in the header but only the relevant ones are set to 1, changing my "#ifdef x" to "#if x == 1" was the solution.

#if (TARGET_CPU_ARM64 == 1)
    #include <sse2neon.h>
#elif (TARGET_CPU_X86_64 == 1)
    #include <emmintrin.h>
#endif