Re: Moving VAX into 21 century :-)

[Jason Thorpe <thorpej%me.com@localhost>]

> On Aug 27, 2019, at 3:01 PM, Johnny Billquist <bqt%update.uu.se@localhost> wrote:
> 
> 
>> - No need for AP (Use for TLS?)
> 
> You need some way of telling where the arguments are for arguments beyond what you can pass in registers. Are you suggesting just some fixed offset on the stack? This can become ugly and error prone...

You could either:

(a) Let the compiler keep track of how it has manipulated the stack and load relative to the SP.

(b) Continue to use the FP register to point at the stack frame and load relative to the FP.

Other platforms already know how to deal with this (getting some arguments from registers and others from the stack) without an AP register.

> I wasn't thinking about space increase in the call, but the return. If you have multiple places of return, you need to both clean the stack, and restore registers at every place you do the return.

Let the compiler optimize this for you.  This is basically just CSE.

-- thorpej