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From: mitchalsup@aol.com (MitchAlsup1)
Newsgroups: comp.arch
Subject: Re: x86S Specification
Date: Tue, 22 Oct 2024 00:03:43 +0000
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On Mon, 21 Oct 2024 22:02:27 +0000, BGB wrote:

> On 10/17/2024 4:34 PM, EricP wrote:
>
> Pros:
>    Technically makes sense for PCs as they are.
> Cons:
>    Looses some of the major aspects of what makes x86 unique;
>    Doesn't really solve issues for x86-64's longer term survival.
>
x86's long term survival depends on things out of AMD's and Intel's
hands. It depends on high volume access to devices people will buy
new every year or every other year. A PC is not such a thing, while
a cell phone seems to be.
>
> Absent changing to a more sensible encoding scheme and limiting or
> removing condition-codes, x86-64 still has this major boat anchor. But,
> these can't be changed without breaking backwards compatibility (at
> least, assuming hardware that continues running x86-64 as the native
> hardware ISA).

Condition codes were never "that hard" of a problem wither in
pipelining nor in operand routing.
>
> Though, ironically, most "legacy x86" stuff could probably be served
> acceptably with emulators.
>
Every try to emulate A24 ? Address bit 24--when we looked at it, it took
more gates to remove it and put a bit in CPUID so applications could "do
the right thing" than to simply leave the functionality there.
>
> If it can't maintain a performance advantage (say, if ARM and RISC-V
> catch up or exceed the performance possible on higher end x86 chips), it
> is effectively done.
>
x86 performance advantage has ALWAYS been in the cubic amounts of cash
flow running through the FAB to pay the engineering team budgets.