SPIRV-Tools : GLSL reference compiler. ( https://github.com/KhronosGroup/SPIRV-Tools )
glslang : GLSL reference compiler. ( https://www.khronos.org/opengles/sdk/tools/Reference-Compiler/ )
shaderc : A collection of tools, libraries and tests for shader compilation. ( https://github.com/google/shaderc )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a gentoo-gpu
For Paludis use this rsync : rsync://gentoo.zugaina.org/gentoo-gpu-portage
If you have a problem : ycarus(-at-)zugaina.org