I propose that the LLVM devs consider adding “swapstack” and “newstack” into the LLVM project officially.
Thanks for the reference. I was going to suggest the ‘preserve_none’ calling convention, applied to asm which does the stack pointer swapping, would be equivalent to swapstack. However that calling convention doesn’t appear to exist - it would be one where the caller is required to save all live values to the stack before jumping.
‘preserve_none’ may be a useful calling convention independent of green threads. Functions which will always use all the available registers benefit from not having to save/restore any of them, if the caller knew to preserve any live values. A green thread context switch is roughly a call that preserved nothing.
Newstack I’m not as sure about. Green thread libraries are likely to put a lot of effort into how stacks are sized, allocated, reused. That seems better as a runtime call.
Thanks