[grg0]

Unfortunately this is a topic that isn't open enough, and architectures change rather quickly so you're always chasing the rabbit. That being said:

RDNA architecture (a few gens old) slides has some breadcrumbs: https://gpuopen.com/download/RDNA_Architecture_public.pdf

AMD also publishes its ISAs, but I don't think you'll be able to extract much from a reference-style document: https://gpuopen.com/amd-gpu-architecture-programming-documen...

Books on CUDA/HIP also go into some detail of the underlying architecture. Some slides from NV:

https://gfxcourses.stanford.edu/cs149/fall21content/media/gp...

Edit: I should say that Apple also publishes decent stuff. See the link here and the stuff linked at the bottom of the page. But note that now you're in UMA/TBDR territory; discrete GPUs work considerably differently: https://developer.apple.com/videos/play/wwdc2020/10602/

If anyone has more suggestions, please share.