I would like to submit this patch to xz to support the Intel compiler (see below)
Rationale: A new version of the Intel compiler (not yet released) requires that _bit_scan_reverse be used via #include <immintrin.h> ; this is because it will be implemented via an inline assembler call. If you use the intrinsic without the #include then at link time there is an undefined symbol [c code], or if in c++ code, there is a compilation error due to undefined name. (In a new version of the Intel compiler, the "intrinsic" name will no longer be known by the compiler.) This problem is seen, for example, in our experimental builds of "cmake" and also "kokkos" BTW I see there is something in "configure" to automatically include immintrin.h and it's referred to in the file ./src/liblzma/common/memcmplen.h; I'm not sure if that's working correctly. I don't know how to configure the "git clone" from configure.ac--I couldn't build. So I downloaded the tar.bz file for xz.5.2.3, configure and build on Linux with CC=icc; in a separate build/ directory. I didn't see evidence that the automatic include was occurring, so I'm doubtful about those lines in the file memcmplen.h which are #include immintrin.h conditionally. I'd be glad to follow up on this if you send me a recipe. As well it is possible to get a free developer license for the Intel c++ compiler for certain open source usages. In any source file that refers to Intel intrinsics, there should be a #include of <immintrin.h> to future-proof the usage. I work for Intel on the Intel C++ compiler team. --Melanie Blower diff --git a/src/common/tuklib_integer.h b/src/common/tuklib_integer.h index a7fda67..830e49e 100644 --- a/src/common/tuklib_integer.h +++ b/src/common/tuklib_integer.h @@ -98,6 +98,15 @@ #endif +//////////////////////////////////////// +// Compiler specific features // +//////////////////////////////////////// + +#if defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 1500) +#include <immintrin.h> +#endif + + /////////////////// // Byte swapping // /////////////////// @@ -168,7 +177,6 @@ # endif #endif
