Re: A question for my personal knowledge.

[kilgallen@eisner.decus.org (Larry Kilgallen)]

In article <87k8u7if6a.fsf@bglbv.my-dejanews.com>, <bglbv@my-dejanews.com> writes:
> Charlie McCutcheon <"cmccutcheon@NOSPAMbegin"@enet.dec.com> writes:
> 
>> Parts of OpenVMS, most recent versions, I think at least 6.2 on.
> 
> At that level of certainty I might as well reiterate my own vague
> recollection. (Unfortunately, when I tried to track down the specifics
> recently I found that DejaNews had not preserved the postings where
> the most detailed and reliable information appeared, and the OpenVMS
> FAQ is short on specifics.)
> 
> Anyway, my recollection is that use of Ada in VMS development started
> with version 4.0 of the operating system.  This would place the
> beginnings of such activity in the 1983-1984 time frame, more or less
> when DEC's first Ada compiler for the VAX came out. It is good
> practice to test new software products by exercising them in-house,
> so this makes at least some sense.

I have a subscription to the VMS source listings, and Charlie is
correct, modulo some VAX-Alpha skew.  I am talking about actual
use for code that ships in the operating system product, not whatever
DEC may use internally for testing the compiler.

> I suppose someone with access to a VMS system could go through system
> executables and shared libraries and watch for the Ada compiler's
> idiosyncracies in code generation. (Things like working out the size
> of everything in bits rather than bytes, for example. Certainly if I
> wanted to search for GNAT-generated code on an x86 I would look for
> sections with a high density of arithmetic shifts left by 5. Similar
> heuristics should work with other compilers and on other platforms.)

I presume that any reasonable Ada compiler would handle that before
emitting object code, and it would never show up.

>> Not major parts mind you.  Some sub-sections where the programmers involved
>> wanted to use Ada.
> 
> My understanding is that the use of Ada resulted in measurable
> productivity gains. Pity I don't have the original reference anymore.

I doubt that DEC has done enough Ada to make such measurements.
It takes a _lot_ of code to filter out "other factors".  See
Marin David Condic's cautious optimism at his company after 10
years of comparisons.

Larry Kilgallen