Comment by gslepak
12 hours ago
Amazing work, one question regarding the guide, it states:
> That same file is the CPU program and the GPU kernel: clang builds it for the host, Metal or CUDA builds it for the device, so a `!` runs the exact same code on either chip.
What exactly is this saying? The guide doesn't really explicitly define `!`, and it's unclear from this sentence whether it's saying that, "clang builds it for the host and Metal, and CUDA builds it for the device", or if it's saying, "clang builds it for the host, Metal, and CUDA, and builds it for the device", or something else entirely.
I will improve that phrasing, thanks.
It just means that Bend compiles to a single .c file, and that file compiles to either Metal or CUDA, via macros, depending on your target. This shouldn't be relevant to most users. It is just a way I found to keep the file small and reuse as much code as possible, rather than rewriting the runtime 3 times (once for C, once for Metal, once for CUDA).