RE: [avr-gcc-list] Miscompilation with GCC 4.5.1 / diagnosis andpossible patch

[Weddington, Eric]

Thanks, Owen. We're going to be taking a look into it.

Not so sure about the results of your patch... I could be wrong, but it looks 
like it's generating some code that's not needed (addition a variable to 0), 
plus another inefficiency.

But we'll go over this in the bug report comments.

Thanks,
Eric Weddington 

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of Owen Taylor
> Sent: Monday, August 16, 2010 2:19 AM
> To: address@hidden
> Subject: [avr-gcc-list] Miscompilation with GCC 4.5.1 / 
> diagnosis andpossible patch
> 
> [ Not subscribed, please Cc: me on replies ]
> 
> Ran into some miscompilation of 16-bit arithmetic with the AVR backend
> in stock GCC 4.5.1. A diagnosis and minimally tested patch can be
> found at:
> 
>  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45291
> 
> Debugging into the GCC internals was more entertaining than digging
> through collections of patches for GCC, so it may be that this is
> fixed somewhere and just not in upstream GCC. But if not, hopefully
> the above is useful.
> 
> - Owen
> 
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