Bug 24124 – ImportC: gcc simd intrinsics not supported by dmd

Building `stb_image.h` from here: https://github.com/schveiguy/draylib/blob/master/raylibc/external/stb_image.h Using the C file: ```c #include "../config.h" #define STB_IMAGE_IMPLEMENTATION #include "stb_image.h" ``` produces a lot of errors for missing intrinsics: ``` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(66): Error: undefined identifier `__builtin_ia32_emms` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(79): Error: undefined identifier `__builtin_ia32_vec_init_v2si` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(122): Error: undefined identifier `__builtin_ia32_vec_ext_v2si` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(161): Error: undefined identifier `__builtin_ia32_packsswb` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(176): Error: undefined identifier `__builtin_ia32_packssdw` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(191): Error: undefined identifier `__builtin_ia32_packuswb` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(205): Error: undefined identifier `__builtin_ia32_punpckhbw` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(219): Error: undefined identifier `__builtin_ia32_punpckhwd` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(233): Error: undefined identifier `__builtin_ia32_punpckhdq` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(247): Error: undefined identifier `__builtin_ia32_punpcklbw` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(261): Error: undefined identifier `__builtin_ia32_punpcklwd` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(275): Error: undefined identifier `__builtin_ia32_punpckldq` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(288): Error: undefined identifier `__builtin_ia32_paddb` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(301): Error: undefined identifier `__builtin_ia32_paddw` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(314): Error: undefined identifier `__builtin_ia32_paddd` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(337): Error: undefined identifier `__builtin_ia32_paddq` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(349): Error: undefined identifier `__builtin_ia32_paddsb` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(363): Error: undefined identifier `__builtin_ia32_paddsw` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(377): Error: undefined identifier `__builtin_ia32_paddusb` /usr/lib/gcc/x86_64-linux-gnu/11/include/mmintrin.h(391): Error: undefined identifier `__builtin_ia32_paddusw` ``` This is not the full list, once I "undefined" these, there were pages and pages more. Basically these are all the SIMD builtins for gcc.

Is there a path through the headers that does not rely on the gcc SIMD intrinsics?

Yes, I can define STBI_NO_SIMD and it will not use the SIMD calls. But this might not be a general solution for projects which don't have that configuration option. Note that I believe LDC has fixed this: https://github.com/ldc-developers/ldc/commit/798f73bd37308abc7aaef21e411f1615c4422022 But DMD may not have that luxury.

Supporting gcc's instrinsic builtins would be a major project to add to dmd. If your project needs them, pragmatically you'll need to use gdc/ldc.

@WalterBright created dlang/dmd pull request #15779 "Issue 24124 - ImportC: gcc simd intrinsics not supported by dmd" mentioning this issue: - Issue 24124 - ImportC: gcc simd intrinsics not supported by dmd https://github.com/dlang/dmd/pull/15779

BTW, dmd supports all the x86 SIMD instructions in the inline assembler.

Guillaume has implemented most of the library of intel intrinsics in his library if they are genuinely required (I have been saying this should be pinched for druntime for a while alas he isn't keen)

(In reply to mhh from comment #6) > Guillaume has implemented most of the library of intel intrinsics in his > library if they are genuinely required (I have been saying this should be > pinched for druntime for a while alas he isn't keen) Can you link to it here, please?

1. dmd does not support gcc simd intrinsics, and is not likely to 2. the library in question has a #define for disabling use of those intrinsics, and it's a 3rd party library Hence, I'm going to resolve this as WONTFIX.

In general, I agree with this result. The unfortunate reality is, many C libraries are going to use the definitions from the local c preprocessor (which is not related to DMD) to make decisions, which means that code simply won't compile with DMD. The only real solution would be for DMD to require a specific set of C headers and C preprocessor that goes with it, and code to that. ImportC with system headers might be a LDC/GDC-only thing.