Re: Avoid treating the stack as an array [Re: "Back & Forth" is back!]

On Sun, 8 Sep 2024 14:56:01 +0000, Stephen Pelc wrote:

On 6 Sep 2024 at 23:03:38 CEST, "Buzz McCool" <buzz_mccool@yahoo.com>
wrote:
>

Would you have any videos talking about Forth locals? You and dxf are
far more adept at stack manipulations than I. I'm thinking I can get a
word up and working with locals and then convert to manual stack
manipulations afterwards if necessary.

>
Don't. You will only become dependent on locals. Use of locals should
be a considered decision.

>
When is it necessary? dxf showed a word w/o locals to have ~%30 fewer
instructions than a word with locals. Is that a common occurrence?

>
We (MPE) converted much of our TCP/IP stack not to use locals. This
was mostly on ARM7 devices, but the figures for other 32 bit CPUs of
the period (say 15 years ago) were similar. Code density improved by
about 25% and performance by about 50%.

These are good examples of "it depends". And also that one should never
start optimising without profiling. I have had similar experiences in
the
other direction (i.e. with locals) with vector maths.
Another observation is that many Forthers do not seem to put much
emphasis
on programming time and code maintainability or readability, which is
easier to achieve by using locals. The code conversion for your TCP/IP
stack must have taken a lot of programming time, but it must have been
worth it because it paid off on another level.
But when to use or avoid locals is an old argument that has long since
been put to rest. It all depends...