CODEWITHSUNDEEP
xcodearmclangneon
patrick
patrick

Reputation: 9742

cannot get NEON intrinsics header to compile in XCode

I have some C++ code using NEON intrinsics. From what I have read, all you need to do is include arm_neon.h to your project.. And then I read that this arm_neon.h header is not actually readily available to you automatically, you have to get it from the web. So I found and added this version to my project:

http://clang.llvm.org/doxygen/arm__neon_8h-source.html

In my project's prefix.pch I added:

#import "arm_neon.h"

And when I try to build on my iPhone6 device (I am not using the simulator), I get a billion errors inside the arm_neon.h file:

enter image description here

Can anyone please explain to me what I am missing here?

Upvotes: 1

Views: 2839

Answers (1)

James Greenhalgh
James Greenhalgh

Reputation: 2491

You've been misinformed about being able to pick up an arm_neon.h from the Internet. Generally the header is not just compiler specific, but compiler version (even compiler revision) specific. For GCC it relies on a number of compiler built in function calls, and from your screenshot of Clang the same holds there. As you'd expect, if the name of these internal-only functions changes, the header will fail to compile.

What surprises me is that you're unable to use an include of whichever arm_neon.h ships with your build environment. The only thing I can think of that would cause this is the build command trying to build for x86_64 (for the simulator) but you say this isn't what is happening. It might be worth checking your build settings one more time.

If you're still not getting anywhere, remember that arm_neon.h is sometimes considered as a system header, so in C++ you might need to #include <arm_neon.h> rather than #include "arm_neon.h" to get the compiler to search the system paths.

Upvotes: 5

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