Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!emperor!richd
From: richd@emperor.scs.com (Richard Doherty)
Newsgroups: comp.sys.apollo
Subject: Apollo CC 5.7 Optimizer bummer
Message-ID: <1991May8.231635.8782@emperor.scs.com>
Date: 8 May 91 23:16:35 GMT
Distribution: comp
Organization: Mentor Graphics IC Group, San Jose, CA
Lines: 39


I have a large program (that loads several other large libraries)
that dies with a segmentation violation.  If I shut off the optimizer
with the -dba flag, the program works flawlessly.  Apollo customer
support could provide no clues.

Question: Has anyone discovered optimizer problems?

Details:
   The program is ported from a Sun system, where it works fine
on full optimization.  Saber-C passed the program with no errors
or warnings running in full interprative mode (for those who don't
have this good tool -- this process will find things such as uninitialized
variables and memory at wanders).  Again, the program runs correctly 
with optimization turned off on the Apollo.

Machine: HP 400t
OS: SR10.3.2 
CC Version: 5.7

The customer rep suggested several things:
1) Trying the compilation at several different levels of optimization.
   I have not done this yet, as it will not likely give me any clues.

2) Look for uninitialized variables.  I believe I have this covered.

I ran dde on the optimized code, and it reported all sorts of optimizations
that were somewhat hard to believe.  Several library routine calls were
merged, when in fact they were referencing different routines.  Lines
of code were reported merged that made no sense.  I decided dde was
lying and ignored it.  Dde often contradicted itself.

Dbx produces a segmentation fault so often as to make
the tool useless on the apollo.

I would like to distill the code to a very simple program that would produce
the same results, so I can send it to apollo.  This may be difficult.

--Rich