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RE: [avr-gcc-list] Gcc bug??
From: |
Brian Cuthie |
Subject: |
RE: [avr-gcc-list] Gcc bug?? |
Date: |
Wed, 3 Mar 2004 08:13:59 -0500 |
I will try to build something that demonstrates the problem. Thanks.
-brian
> -----Original Message-----
> From: address@hidden
> [mailto:address@hidden On Behalf Of Klaus Rudolph
> Sent: Wednesday, March 03, 2004 1:45 AM
> To: address@hidden
> Cc: address@hidden
> Subject: Re: [avr-gcc-list] Gcc bug??
>
> Brian Cuthie wrote:
> >
> > I'm having some problems with an app that uses AvrX and gcc
> (v. 3.3.1)
> > on an ATmega16. In the interrupt routine for the TWI I
> write a static
> > with a code that indicates its current state. In an effort
> to debug a
> > different problem I compiled the code without any optimization.
> >
> > While I did discover the original problem I had been hunting, I
> > started to see some very unreliable behavior with the TWI.
> After some
> > investigation I determined that the state variable
> (mentioned above)
> > was getting written with an unreasonable value (not a valid state).
> > The correct state value that should have been written into the
> > variable is "0". Further experiments revealed that memory
> corruption
> > (at least directly into the variable's memory location) was
> not the problem.
> >
> > What I then determined is that the "0" register (r1)
> contained the value 8!
> > This, not coincidentally (and looking at the disassembled code) is
> > exactly the value that's being incorrectly written into the
> static state variable.
> > Interestingly, turning on any level of optimization seems
> to fix it,
> > at least as observed by the TWI port handler not hanging.
> >
> > I was wondering if anyone else has seen anything like this,
> or has any
> > advice or suggestions.
>
> Can we have a look inside the code itself? Please cut all
> unneeded stuff away and send us the source code and the
> Makefile with the good and the corrupt compile options. It is
> a bit difficult to say: Is it possible that gcc has a bug or
> not :-) Please comment the code that the corrupt lines can be
> found fast.
>
> Thanks
> Klaus
>
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