🚀 go-pugleaf

dmurdoch@mast.queensu.ca (Duncan Murdoch) writes:

>>Waht difference does this make for execution time? The cleanup code has to be
>>executed for every invocation, whether it is included with the callers or the
>>called code. Of course it does make difference for the code size.

>A Pascal routine with 20 bytes of parameters can return and clean up with 
>the single instruction:

>     retf 20

>On all 80x86 cpus, this takes the same time (plus or minus a cycle) as the 
>plain retf.  The advantage comes because that's all that's needed; a return 
>from a C convention routine must be followed by manual adjustment of 
>the stack pointer.

e.g.  sub sp, 20   ... which takes 2 cycles on a 386. You will have 
to have a very short called routine before you can see any difference.

>Duncan Murdoch