> You can also prove this to yourself by contriving an IR function that contains more SSA registers than machine registers: you'll see that, in addition to any ABI constraints, LLVM will be forced to spill any excess SSA registers back onto the stack.
Having more SSA register than machine registers does not mean there will be any spilling as unlike SSA registers, machine registers can be reused once the old value is no longer needed.
Sure. To be more precise: you can prove this to yourself by contriving a function that has more live variables/values than there are machine registers.
Having more SSA register than machine registers does not mean there will be any spilling as unlike SSA registers, machine registers can be reused once the old value is no longer needed.