Where can I find crc32intrin.h?

Question

Where can I find the header file crc32intrin.h ?

It is related to zlib.

I am converting C++ code to Java, and this name is repeatedly coming up, but I can't find it.

Answer 1

The Clang compiler ships it. GCC does not. Here is its documentation and a link to the source code: https://clang.llvm.org/doxygen/crc32intrin_8h.html

Answer 2

Normally you should just include <immintrin.h> .

Intel's intrinsics guide documents _mm_crc32_u64 , _u32, etc. as being in <nmmintrin.h> (new in Nehalem?) - https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#techs=SSE_ALL,Other&ig_expand=6243,519,1563&text=crc32

GCC does provide these intrinsics (in smmintrin.h as it turns out), but crc32intrin.h is a clang implementation detail.

These days usually best to include immintrin.h to pull in all known intrinsics. (Unfortunately getting a bit bulky with AVX-512 having boatloads, so not great for compile times.) GCC and clang will stop you from using intrinsics you didn't enable with options like -march=x86-64-v3 (similar to haswell but without tune=) or x86-64-v2 (similar to nehalem ).