From:	Ben Peddell <killer DOT lightspeed AT bigpond DOT com>
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Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Bug 00314 -- div() still broken
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Date:	Sat, 26 Apr 2003 23:17:04 +1000
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

Eric Rudd wrote:
> Ben Peddell wrote:
> 
>> Obviously, some sort of optimization puts the div_t structure in 
>> %edx:%eax instead of 16(%ebp). It would be a good optimization if it 
>> didn't break the libraries. 
> 
> 
> Yes, indeed.  So, it looks as if there is a gcc bug here.  Where are the 
> calling conventions documented?  I couldn't find them in the gcc.ixx 
> docs.  I think I ought to isolate this and submit a bug report, if gcc 
> is indeed at fault.  I suppose a workaround would be to recompile libc, 
> but then one wonders whether all the other libraries are also broken.
> 
> -Eric Rudd
> rudd AT cyberoptics DOT com
> 

I'm pretty sure I saw somewhere that char, short, int and long are 
returned in eax. long long is returned in edx:eax. Anything longer than 
that is returned in memory.
I guess that without the optimization, gcc returns the div_t structure 
in memory, but with the optimization, gcc returns it in edx:eax since it 
sees that it is the length of a long long.

GCC 3.2.1 (the gcc I have under DJGPP) does not optimize the div_t into 
a long long when given -O3 or -fomit-frame-pointer.
In fact, -fomit-frame-pointer does nothing.

I went to www.delorie.com to get gcc 3.2.2, and had a look at your bug 
report whilst I was there.
What command line did you use?

Anyway, I'm getting gcc 3.2.2.
I'll get back tomorrow when I install it.

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