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From: Paul Rubin <no.email@nospam.invalid>
Newsgroups: comp.lang.forth
Subject: Re: Avoid treating the stack as an array [Re: "Back & Forth" is back!]
Date: Sun, 15 Sep 2024 12:39:28 -0700
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anton@mips.complang.tuwien.ac.at (Anton Ertl) writes:
> So by keeping the values on the stack you not just eliminate their
> repeated mention, but also eliminate one branch of the IF.

Is the repeated mention just a matter of DRY, assuming the compiler puts
the locals in registers so that the extra mention doesn't transfer them
between stacks a second time?  I do prefer your version where you factor
out VIERROR.

I wonder whether Moore's 1999 aversion to locals had something to do
with his hardware designs of that era, where having more registers
(besides T and N) connected to the ALU would have cost silicon and
created timing bottlenecks.  Today's mainstream processors have GPR's
anyway, but I wonder what the real problem was with stack caches like
the CRISP:  https://thechipletter.substack.com/p/at-and-ts-crisp-hobbits

Commenters there say CRISP failed basically because its early
implementation was buggy, it lost an important design win because of the
bugs, and AT&T management then gave up on it.

I remember the SPARC had "register windows" but I don't know if that's
similar or what went wrong with them.