Re: huge executable??

[gisle@krake.ii.uib.no (Gisle S�lensminde)]

In article <3920DA5B.2F56@club-internet.fr>, DELCOURT J�r�me wrote:
>tmoran@bix.com wrote:
>> 
>> > why is the .EXE produced by Ada so much bigger?
>>   It's not Ada, it's the particular compiler's run-time for the
>> particular OS.  Your Hello program compiled to 67K with a different
>> compiler.  Dropping the "with ada.text_io" and raising an unhandled
>> "hello_world:exception" instead, that went down to 37K.  Looking at
>> some old DOS .com programs in Ada, I find a 100 line one that
>> HTML-izes a text file and compiles to 19K.  The same program,
>> compiled to run under 32 bit Windows, is now 73K.
>>   The more important question is, is size a problem with real
>> programs that do something substantial.

>
>I think that a reduced executable size is important, since that
>allows a better use of the CPU cache memory, so that could improve
>the speed of the program.

Not quite correct. If some part of the program is unused it will
quickly be flushed out of instruction cache and remain outside,
if ever comes there. It will affect load lime and harddisk space,
but not instruction cache.

Instruction cache is important when you try to unroll code. 
If the codesize no longer fit instruction cache, you will probably 
see a significant performance hit. If you have code doing computational 
work, that part of the code should fit the instruction cache, 
but that have nothing to do with size of the executables on
your hard drive. 

>
>Concerning that problem, I suspect that, with GNAT, there is not
>a good elimination of the unused code.
>
>Sincerely, Jerome Delcourt


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Gisle S�lensminde ( gisle@ii.uib.no )   

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