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From: zyg@geovision.UUCP (Zygmunt Wiercioch)
Newsgroups: comp.unix.wizards,comp.lang.c,comp.unix.questions
Subject: Re: New feature of Ultrix C compilers
Message-ID: <192@geovision.UUCP>
Date: Sat, 3-Oct-87 12:35:14 EDT
Article-I.D.: geovisio.192
Posted: Sat Oct  3 12:35:14 1987
Date-Received: Wed, 7-Oct-87 06:34:15 EDT
References: <867@sask.UUCP>
Reply-To: zyg@geovision.UUCP (Zygmunt Wiercioch)
Organization: Geovision Corporation, Ottawa, Canada
Lines: 61
Xref: dciem comp.unix.wizards:4062 comp.lang.c:4330 comp.unix.questions:3773
Summary: VAX C version 1.0 and library searches

In article <867@sask.UUCP> coleman@sask.UUCP (Geoff Coleman @ College of Engineering) writes:
>
>Ok all you experts out there who can explain this new
>feature of Ultrix 2.0 and its C compilers.
>We just installed Ultrix 2.0 on a uVax-II. Last night I 
>recompiled a couple of C programs using both the VAX C 
>compiler and the default comnpiler. The new executables were 
>~2.5 times the size of the old one. 
>

Did the executables grow with cc and vcc ?  I suspect that the executables
grew in size only when you used vcc and lk.  There is a bug in the vcc/lk
combination of VAX C on Ultrix 2.0 (at least the version we have).  The
problem occurs with modules that include <stdio.h> and/or <math.h>.  The
vcc compiler marks externals in these headers in such a way that the lk linker
brings in all functions having refernces to these externals. The problems
are errno in math.h and the io buffer in stdio.h I belive. Can't check, 
our 2.0 machine is off the net at moment, but try an ln on a simple object 
file.

A simple test comsisting of these three files should show this behaviour:
main.c:
	#include <stdio.h>
	main()
	{ a(); }
a.c:
	#include <stdio.h>
	a()
	{ printf ("Function a was called\n"); }
b.c:
	#include <stdio.h>
	b()
	{ printf("B was called\n"); c(); }

Now vcc a and b and place in a library.  Note that function c is not
in the library.  vcc main, and serach the library containing a and b.
You will get c as an unresolved.  If c were in the library, it would
go into the executable.  As a result, if you compile and link using vcc,
and use libraries, your executables will become huge, since virtally all
the functions in your libraries will be dragged in, needed or not.

The other big problem I have with VAX C on Ultrix is that it issues
warnings about constructs such as:
	#if 3b2
	...
	#if tahoe
	..
which <math.h> is full of.  The lk linker reports all modules
which were compiled with warnings, resulting in a lot of junk output.
In the lovely VMS LK%W%... style too. :-)

VAC C does do a good job of optimizing the code for the VAX architecture,
but it is not usable in the current state.  Sure hope DEC gets it right
with version 1.1.


-- 
Zygmunt Wiercioch     613-722-9518
GeoVision Corp, 350-1600 Carling Ave
Ottawa Canada K1Z 8R7
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