C Compiler to SPIR-V

Have a look at QBE as it may provide basic optimizations and some significant performant boost: cproc + QBE and I get 70% of gcc 13.2 -O2 speed in my benchmarks, tinycc is 2 times slower than gcc 13.2 -O2 in the same benchmarks (my benchmarks are very basic, but it shows...).

We are talking gcc complexity is grotesque/absurd for those 30%, not to mention this is now brain damaged c++ (one of the biggest mistakes in open source software ever).

I know QBE is for CPUs, but maybe there is something there for GPUs.

QBE has no support for SIMD last I looked into it, so I don't think it would be appropriate for an SPMD language. https://todo.sr.ht/~mpu/qbe/5

It's common for shader compilers to invent their own IR, like Shadey and Slang IR.