Wouter van Ooijen escreveu:
>   > Another stupdity is the subroutine argument passing conventions. =

> C18 uses a
>   =

>> caller-clean model.  =

>>     =

>
> This the default for C. I agree it is a stupid choice.
>   =

With the callee cleaning the stack it would be impossible (or at least
very difficult) to have functions with variable-length argument lists
like printf.

For some architectures it adds more complexity also, because first the
return address need to be removed from the stack and saved, then the
stack pointer must be incremented (decremented for some) and the return
address finally used to return.

The caller always knows how many bytes it pushed onto the stack, the
callee don't. If the callee cleans the stack and there is some mistake
with the function prototypes (or the equivalent) you get a hard crash.
If the caller cleans, you may have a hard to find bug.

Some processors have an unlink and return instruction that does this
automatically, but others not.

Isaac

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