[Info-vax] CPU architectures, was: Re: problem with 64-bit pointers in C

[Jan-Erik Soderholm]

Den 2018-02-13 kl. 14:00, skrev already5chosen at yahoo.com:
> On Tuesday, February 13, 2018 at 11:35:37 AM UTC+2, Jan-Erik Soderholm wrote:
>> Den 2018-02-13 kl. 09:27, skrev Simon Clubley:
>>> On 2018-02-13, Jan-Erik Soderholm <jan-erik.soderholm at telia.com> wrote:
>>>> Den 2018-02-13 kl. 07:36, skrev Simon Clubley:
>>>>>
>>>>> Those code size changes from VAX to Alpha were not helped by the lousy
>>>>> code density on Alpha when compared to VAX.
>>>>
>>>> But that was not a mistake in the Alpha part, that is a known and
>>>> predictable difference between CISC and RISC. You get higher speed
>>>> instead due to a "cleaner" architecture.
>>>>
>>>> And as the hardware and memory development has been, code density
>>>> has hardly been an issue as such.
>>>>
>>>
>>> I am currently operating under somewhat different memory constraints
>>> for my Macro-32 and Macro-64 code. :-)
>>>
>>
>> But you refered to the "lousy code density on Alpha".
>>
>> Your specific needs are probably not a valid benchmark to
>> evalute processor architectures against. :-)
>>
>>>>>
>>>>> Macro-32 is a much nicer assembly language than Macro-64 is.
>>>>>
>>>>
>>>> For the same reason, a CISC environment does more with fewer
>>>> instructions. Also a know effect from RISC, to get higher speed.
>>>>
>>>
>>> This is somewhat architecture specific, even on RISC. ARM is a much
>>> nicer architecture to write assembly language for than Alpha.
>>
>> ARM was to a higher degree designed for assembled programming.
>> Then in later days ARM has grown higher up into areas where other
>> processorn (such as Alpha) had made its living. And in the same
>> way, Alpha was designed no as much for assembler programming,
>> but for efficient compiler designs and high speed.
>>
>>>
>>>> And at the same time, you where expected to switch from assembler
>>>> to higher lever languages. And if I'm not wrong, it is easier to
>>>> design a good compiler on a cleaner architecture (like Alpha).
>>>>
>>>
>>> Alpha is cleaner than x86 (and hence writing compilers for Alpha is
>>> easier) but VAX was also a clean architecture when it came to
>>> writing compilers.
>>>
>>
>> Of course it helps to write assembler on a very-CISC architecture,
>> since each instruction does more. But with the expense of speed
>> (at that time).
>>
>> Today, even x86 has got some steorids to get up in speed in a way
>> that was not predicable 15-20 years ago.
> 
> It was easily predictable 15-20 years ago.
> Pentium Pro is 22 y.o. and it clearly showed the way to anybody willing to see.
> Exactly 20 years ago is when Intel released 2nd-generation Pentium-II that demonstrated that fast x86 is not just possible technically, but could be manufactured cheaply and does not have to consume a lot of power.
> And 18.5 years ago AMD demonstrated that it's possible to design fast x86 without multi-billion budget.
> 
> Make it 25 years instead of 15-20 and you would have a point.

Whatever...


> 
>>
>>> Don't confuse a simple architecture with a clean architecture.
>>>
>>
>> I was saying that the Alpha code density is "lousy" by-design
>> and not by some mistake.
>>
>>
>>> Simon.
>>>
>