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Subject: Re: Introducing "No-Moore's Law"

Author: Robert Hyatt

Date: 08:48:47 03/06/03

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On March 05, 2003 at 22:38:44, Jeremiah Penery wrote:

>On March 05, 2003 at 18:26:10, Robert Hyatt wrote:
>
>>The point of my comments is that Intel sets a sort of standard, and if someone
>>follows along,
>>but are not quite all there, it can cause problems.  I had this problem with
>>Cyrix years ago as
>>their 387's were actually more accurate than Intel's, not to mention faster.
>>And they would
>>make every diagnostic program on the planet sound the alarm with floating point
>>errors.  :)
>>
>>And I got tired of the phone calls asking about it and quit recommending them.
>>:)
>
>Why should a company be penalized for making a better product?


Making a processor that is "PII-compatible" but really isn't, is "better"?

My point.


>
>>>>If everyone was a compiler expert, this might be forseeable.  But they aren't.
>>>>And I doubt
>>>>most would think that -target=pentiumII would break a processor that is supposed
>>>>to be
>>>>compatible.
>>>>
>>>>Can I say more?
>>>
>>>A lot of the average programmers probably don't even know to use a specific
>>>processor target (when using GCC), or they use some other compiler.  I'd expect
>>>someone who uses specific processor targets in their compile to have some basic
>>>understanding of assembly.
>>
>>I wouldn't.  If you look at the simple help files, you might see:
>
>And you think even 5% of people look at help files? :)

Again, my point.  I don't think .01% of people look at help files.  They would
assume
that their PII-compatible processor really is PII-compatible and contact me
about a bug
in _my_ program.

However, I'll bet that anybody compiling a C program they write will do a "man
gcc"
on a unix box because they have heard about -O and want to see what else there
is to
make their handy-dandy chess engine as fast as possible.


>
>>"-target=pentiumII"  This causes the compiler to optimize the program for
>>optimum
>>performance on the intel Pentium II processor.  (hypothetical option and
>>explanation
>>of course.)
>>
>>That could get any beginner to try it and it would work.  And introduce an
>>unknown
>>incompatibility with AMD.
>>
>>>
>>>>For the streetlight issue, the streetlight is not hanging over the street in
>>>>plain sight.  It is
>>>>buried under the light pole, with a door with a combination lock on it that has
>>>>to be opened
>>>>so it can be seen.  Do you expect John/Jane Doe to know that when there is no
>>>>sign on the
>>>>pole that says "look here for compatibility issues"???
>>>>
>>>>I don't.
>>>
>>>I'm not sure I expect Jonn/Jane Doe to understand that you have to even look for
>>>traffic, whether the light says 'WALK' or not.  Obviously, there are a lot of
>>>people who fit in that category.
>>
>>The problem here is that they don't even know there _is_ traffic.  Who would
>>think
>>that the compiler produces an instruction that a compatible processor doesn't
>>support?
>>They don't even understand assembly language, much less instructions, much less
>>any
>>more details that are necessary to even understand that there might be a
>>problem.
>>
>>Remember, that intellect represents 99%+ of all the computer users on the
>>planet.
>
>And probably 99.9% of those people are not going to using anything but
>store-bought programs, which will check for processor support (or use basic
>386-like instructions that MSVC emits), so they never run into this kind of

Well over 1M _different_ IP addresses has downloaded Crafty.  When you consider
that places like AOL.com appear to use one IP for _many_ customers, you can
figure
that maybe that number is 2M or higher.

if .1% = 2M, then you must believe there are 2B computers on the planet.

I do a _lot_ of continuing education courses here at UAB.  Which puts me into
contact with
"rank beginner" type computer users.  And _all_ have downloaded freeware
programs.  From
screen-shot capturers, to chat programs, to you-name-it.  I'd bet that way over
50% of all
computer users have sampled freeware programs, which makes this an issue again.
Of course
AMD might have fixed the cmov problem in later versions, I don't know since I
don't use 'em.
But the mine was laid and armed, and way more than you might guess stepped on
it.

As far as using "basic 386 instructions" that _really_ makes me want to puke.
Why do you
think the Intel folks added the new instructions?  Just to be incompatible?  Or
to speed things
up?  I bugged the GCC folks for a _long_ time about cmov, for example, because I
had used
a similar instruction on the early alpha processors and thought it was an
interesting solution
to a known problem.

Instead of using the new stuff, you seem to be suggesting that it is better to
only use what is
available on _both_ processors, which (to me) is senseless.




>problem.



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