Re: Caller/Callee saved Registers

pmagun@iiic.ethz.ch (Paul Jakob Magun) writes:
>I'm having some difficulty grasping the key idea behind the division in
>caller/calleesaved registers:


Preston Briggs writes:
>The idea is a compromise.


I've often thought the solution to this problem could easily be solved in
hardware. A call instruction that indicates which regs need saving in a
bitmask could be combined with a stack-frame-creation instruction
(similar to the mc68k family's link instr.) that logically ands this
bitmask with another bitmask that indicates which regs the routine needs
to trash. The result of this logical and would be the actual regs that
need saving. This could all be done in software, but it would be far
more efficient in hardware.


so why hasn't this been done yet?


gears,
ye wilde ryder
--
robertsw@agcs.com
[The vax call instruction has a save mask that supports a callee saves
convention. It's slower than a snoozing slug. -John]
--

Return to the comp.compilers page.
Search the comp.compilers archives again.