Support C++ translation units

[hfp]

Immintrin-debug is implemented in C which is also desired (given that C code should be able to make use of this project). However, using the Immintrin-debug header file in a C++ translation unit will cause at least compiler errors (as C++ is less permissive). Anyhow, a lot of warnings are also present with C code at higher warning levels (let alone extra and/or pedantic warnings).

How to reproduce:

• Git-clone the master revision of LIBXSMM: git clone https://github.com/hfp/libxsmm.git
• Copy immintrin_dbg.h to include directory: cp immintrin_dbg.h /path/to/libxsmm/include
• Edit https://github.com/hfp/libxsmm/blob/master/include/libxsmm_intrinsics_x86.h#L37 (0 -> 1)

To translate using a C++ translation unit:

• cd /path/to/libxsmm; make test-cpp

To compile with a lot of warning flags:

• C++ translation: cd /path/to/libxsmm; make PEDANTIC=2 test-cpp
• C89 translation: cd /path/to/libxsmm; make PEDANTIC=2

Immintrin-debug may switch to some more sophisticated function-decoration at least with respect to "static" and "inline" (different meanings in C++ and C; for the latter "inline" for instance was only introduced in C99 and may be emulated prior to this standard).

I understand that not all of the above warnings will be resolved easily (nor they should as effort is not justified). However, it should work with C++ translation units.

---

Btw, compilers (regardless of C and C++) may or may not allow intrinsics with/without prototype functions plus if prototypes are present they may differ slightly between Intel and GNU intrinsic headers (aka void* vs e.g. float* in some places etc.). For the latter, casts may assume target signature with float* (or stronger type in general) even if say Intel's prototype has void* (assuming the stronger type works with any compiler as type-"promotion" [demotion] to void* is applied automatically and considered safe).

[izard]

Thank you for the bug report Hans! The bug report comes in three parts: 1. C++ compile errors. 2. C89 compatibility. 3. Compile warnings at higher warning levels.

1. C++ compile error is a recent regression I'll fix with the highest priority.
2. I don't know how to make it C89 compatible while still having it as a .h file only. (Adding .c file and compile step with changes you suggested will fix it of course, but I can't do that now (can discuss offline))
3. Then will see if/how I can deal with pedantic warnings.

[izard]

I've committed fixes (type casts) that make it compile for me with c++ icc and gcc (with default warning levels only).

[hfp]

Thank you!

I found some more missing AVX-512 intrinsics:

• _mm512_cmp_epi32_mask
• _mm512_mask_blend_ps
• _mm512_and_epi32

There are may be more. I will build a more complete list.

[izard]

added __mm512_adn, all 512 blends. Can't add cmp - have to add manually as parser does not process TRUE and FALSE cases in switch.