Building on RISC-V 64bit on Linux

[Cryolitia]

Since #6 , is there any possible that openpgl could support riscv64gc.

I am building it on Arch Linux RISC-V :

1. c++: error: unrecognized command-line option ‘-msse2’
   full log: https://archriscv.felixc.at/.status/log.htm?url=logs/openpgl/openpgl-0.6.0-1.log
2. I add -DOPENPGL_ISA_SSE4=OFF and -DOPENPGL_ISA_AVX2=OFF then it's a fatal error Must have at least one ISA enabled.
3. I delete the lines below
   

   openpgl/CMakeLists.txt

   Lines 69 to 75 in 17ddb61

   	if(NOT (OPENPGL_ISA_NEON OR
   	OPENPGL_ISA_NEON2X OR
   	OPENPGL_ISA_SSE4 OR
   	OPENPGL_ISA_AVX2 OR
   	OPENPGL_ISA_AVX512))
   	message(FATAL_ERROR "Must have at least one ISA enabled.")
   	endif()

   
   And then

/build/openpgl/src/openpgl-0.6.0/openpgl/../third-party/embreeSrc/common/math/../sys/intrinsics.h:15:10: fatal error: immintrin.h: No such file or directory
   15 | #include <immintrin.h>
      |   

I would like to know whether openpgl is glad to continue to support riscv64

[Cryolitia]

I have managed to port openpgl to use simde, now it could be built on Arch Linux RISC-V. I would like to hear openpgl's maintainers insights about how to port it to widely platforms.

Link: Cryolitia-Forks@77074e2

[wszqkzqk]

I have managed to port openpgl to use simde, now it could be built on Arch Linux RISC-V. I would like to hear openpgl's maintainers insights about how to port it to widely platforms.

Link: Cryolitia-Forks@77074e2

I think your work is very valuable. However, it looks like a temporary fix rather than a feature that can be integrated into the project directly.

According to the README of simde's explanation about SIMDE_ENABLE_NATIVE_ALIASES:

Unfortunately, this is somewhat error-prone due to portability issues in the APIs, so it's recommended to only do this for testing.

In some cases, there will be conflicts like error: conflicting declaration ‘typedef simde__m128i __m128i’.

If you want to officially integrate simde in a project, you may not use SIMDE_ENABLE_NATIVE_ALIASES, and you may add the simde prefix to the related functions. The current method may be more suitable as a temporary fix.

This may also require more discussion.

[Cryolitia]

I'm stuck at how to deal with the code in third-party/embreeSrc. It seems like just copied from embree. If I just modify the source code in openpgl, it could make it hard to sync with upstream. The current work is just a work around to just package it, I would like to write a more generic PR after discussing.