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From: "G.B." <bauhaus@futureapps.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Wed, 7 Dec 2016 11:04:00 +0100
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Xref: news.eternal-september.org comp.lang.ada:32649
Date: 2016-12-07T11:04:00+01:00
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On 07.12.16 02:08, Dennis Lee Bieber wrote:
> 	(Was a nice idea -- but the overhead of all the protection handling
> bogged it down too much to get a foot-hold, or even a hand-hold <G>)

The article https://en.wikipedia.org/wiki/Intel_iAPX_432 and
its siblings mention a few specifics, hinting at how not the
entire design might have failed. In no particular order:

-  bit-alignment, not word-alignment,
-  two-chip CGP speed limited by wiring on the board,
-  no (small?) caches, few registers
-  the compiler has routinely used slow general instructions,
    even when much faster alternatives would have worked
    (e.g., a call vs a jump, enter_environment for each
    use of a variable)
-  always call-by-value

But given this kind of support in hardware, is it unthinkable
to have special pieces of hardware that carry out assertion checking
specially? I.e., have the compiler translate the check into some
separate implementation running alongside the "real" program.
One that only reads memory, and that either stops that program or,
if so requested in the program using a dedicated exception handler,
activates the handler in the real program.

-- 
"HOTDOGS ARE NOT BOOKMARKS"
Springfield Elementary teaching staff