going from SunOS 5/SparcWorks -> Linux/gcc

going from SunOS 5/SparcWorks -> Linux/gcc

[Brian Hill]

I have an 15-year old C program (which I didn't write) that compiles and 
runs fine with SparcWorks cc on Sun SPARC with SunOS 5.10.

It compiles on CentOS 5 64-bit with gcc 4.1.2 but core dumps all over 
the place.

Switching to 32-bit compile doesn't help much.

I did as much debugging as I could, but seems to come down to liberal 
use of memory that the SparcWorks compiler accommodates that gcc doesn't 
by default.

Is there some simple compiler option or other measure I can take to 
compile/run the code with gcc?

Rather than get into the details of the code, I figured I start with 
this angle.

Thanks!

Brian

Re: going from SunOS 5/SparcWorks -> Linux/gcc

[Steven Bosscher]

On Thu, Apr 29, 2010 at 8:25 PM, Brian Hill <bchill@bch.net> wrote:
> I have an 15-year old C program (which I didn't write) that compiles and
> runs fine with SparcWorks cc on Sun SPARC with SunOS 5.10.
>
> It compiles on CentOS 5 64-bit with gcc 4.1.2 but core dumps all over the
> place.
>
> Switching to 32-bit compile doesn't help much.
>
> I did as much debugging as I could, but seems to come down to liberal use of
> memory that the SparcWorks compiler accommodates that gcc doesn't by
> default.
>
> Is there some simple compiler option or other measure I can take to
> compile/run the code with gcc?
>
> Rather than get into the details of the code, I figured I start with this
> angle.

This kind of question really doesn't belong here but on gcc-help. But
while we're here...

The standard 1st questions are:
1) Did you compile with -Wall -Wextra and solve all warnings?
2) Did you try with -fno-strict-aliasing?

There is just not enough information in your question to be more helpful.

Good luck,

Ciao!
Steven

Re: going from SunOS 5/SparcWorks -> Linux/gcc

[Paweł Sikora]

On Thursday 29 April 2010 20:35:23 Steven Bosscher wrote:

> The standard 1st questions are:
> 1) Did you compile with -Wall -Wextra and solve all warnings?
> 2) Did you try with -fno-strict-aliasing?

for legacy code, the '-fwrapv' could be helpful.

[wwwdocs] PATCH for Re: going from SunOS 5/SparcWorks -> Linux/gcc

[Gerald Pfeifer]

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Hi PaweÂł,

On Thu, 29 Apr 2010, PaweÂł Sikora wrote:
>> The standard 1st questions are:
>> 1) Did you compile with -Wall -Wextra and solve all warnings?
>> 2) Did you try with -fno-strict-aliasing?
> for legacy code, the '-fwrapv' could be helpful.

your mail reminded me that we could/should clarify this in our bug 
reporting instructions.

The patch below, which I just committed, does that.

Thanks for the hint!

Gerald


Index: bugs/index.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/bugs/index.html,v
retrieving revision 1.107
diff -u -r1.107 index.html
--- bugs/index.html	24 Apr 2011 09:51:55 -0000	1.107
+++ bugs/index.html	25 Apr 2011 20:58:56 -0000
@@ -51,10 +51,11 @@
 <a href="#known">list of well-known bugs</a> and, <strong>if possible,
 try a current release</strong> or development snapshot.</p>
 
-<p>Before reporting that GCC compiles your code incorrectly, please
-compile it with <code>gcc -Wall -Wextra</code> and see whether this shows
-anything wrong with your code that could be the cause instead of a bug
-in GCC.</p>
+<p>Before reporting that GCC compiles your code incorrectly, compile it
+with <code>gcc -Wall -Wextra</code> and see whether this shows anything
+wrong with your code.  Similarly, if compiling with
+<code>-fno-strict-aliasing -fwrapv</code> makes a difference, your code
+probably is not correct.</p>
 
 <h2>Summarized bug reporting instructions</h2>