Re: Rational Apex Ada Linker

["Samuel T. Harris" <u61783@gsde.hso.link.com>]

Jeff Creem wrote:

> I have been "working" with rational for 6 months or so on this issue and
> the completely abismal code generation of the Apex product. I have
> gone through the proper chanels but Rational says they have never heard
> anyone complain about he code generation or huge executables except for me!

We've never complained because Apex has never been our target compiler
either.


> In comparing code generated by Apex to code generated by GNAT or
> even Rationals SunAda product, Apex produces bloated code which runs about
> 1.8 - 3.0 time slower.

I've run PIWG on GNAT, VADS and Apex 2.0 on our SGI's and they each
consistently
run within 10% of each other (taking everything in account). Actual
performance
varies within each groups of tests, but the execution speed is
comparable.
I'll be running the ACES suite when I get a chance.

Apex 1.4 was another story, being "dismally" slower. With the inclusion
of
VADS code generator technology, Apex has become a viable target
platform.

I wonder which version of Apex you (Jeff) compared (you didn't specify).

> But you only pay 16,000 to 20,000 for the tool set. The compiler
> is really just a bonus. The real reason you want to pay that much is for
> the troublesome Language sensitive Editor (that automatically "fixes"
> closing parenthesis (like the ] in LISP and we all know what a powerful
> bug inducer this is).
> 
> Anyhow to make a long story short. I know of know of no fix for the problem.

For large systems, the Apex context switch OPTIMIZATION_OBJECTIVE has a
lot
to do with inlining. When set for TIME, many procedure calls will be
inlined,
eventhough no pragma is used. This can create large executables.
Resetting
this to SPACE will negate automatic inlining. I suggest you (Jeff and
Kirk
from a previous post) try this and see if this helps.

> Try going to your management and telling them that even though you've
> already spent multiple thousands on the Apex environment and compiler that
> you need a few more thousand to purchase VADSself from rational so that
> you can get reasonable executable sizes.

Our main concern with a target compiler is speed. At the moment, we
extensively
use the Apex RCI to generate target loads using the VADS compiler. Who
knows
what we'll be using next year. But we'll still be using the Apex for
development no matter what target compiler we plug into it.

-- 
Samuel T. Harris, Senior Engineer
Hughes Training, Inc. - Houston Operations
2224 Bay Area Blvd. Houston, TX 77058-2099
"If you can make it, We can fake it!"