[Info-vax] x86-64 VMS executable image sizes and memory requirements ?

[Chris Scheers]

Simon Clubley wrote:
> On 2019-12-18, John Reagan <xyzzy1959 at gmail.com> wrote:
>> We're building everything NOOPTIMIZE so it isn't worth looking at.
>>
>> That said, 
>>
>> EDTSHR.EXE, Alpha, optimized: 493 blocks on disk, 179,712 bytes of code
>> EDTSHR.EXE, Itanium, optimized: 724 blocks on disk, 302,960 bytes of code
>> EDTSHR.EXE, x86, NOT optimized: 589 blocks on disk, 227,120 bytes of code
>>
> 
> Thanks, John.
> 
> I'm amused that x86 not optimised is better than Itanium optimised. :-)

That's not surprising at all.  VAX and x86 are byte oriented CISC 
designs from when memory and CPU speeds were about the same and memory 
was very expensive.  They are very memory space efficient.

Alpha and Itanium are at the other extreme as RISC designs with fixed 
length instructions designed to work when memory is much slower than the 
CPU, but also much cheaper.  These fixed length instructions are less 
memory space efficient than the CISC instructions.  Itanium can be very 
memory inefficient.


> Code density on Alpha is lousy compared to VAX and from what I could tell
> from reading the Itanium manuals, Itanium appeared to have even worse
> code density.
> 
> Simon.
> 


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