alt Hacker NewsSo every function call will need to spill even more call-clobbered registers to the stack!
Like, I get that leaf functions with truly huge computational cores are a thing that would benefit from more ISA-visible registers, but... don't we have GPUs for that now? And TPUs? NPUs? Whatever those things are called?
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With an increase in available registers, every value that a compiler might newly choose to keep in a register was a value that would previously have lived in the local stack frame anyway.
It's up to the compiler to decide how many registers it needs to preserve at a call. It's also up to the compiler to decide which registers shall be the call-clobbered ones. "None" is a valid choice here, if you wish.
Why does having more more registers lead to spilling? I would assume (probably) incorrectly, that more registers means less spill. Are you talking about calls inside other calls which cause the outer scope arguments to be preemptively spilled so the inner scope data can be pre placed in registers?
Most modern compilers for modern languages do an insane amount of inlining so the problem you're mentioning isn't a big issue. And, basically, GPUs and TPUs can't handle branches. CPUs can.
Most function calls are aggressively inlined by the compiler such that they are no longer "function calls". More registers will make that even more effective.