RE: [avr-libc-dev] LPM instructionsin optimized code causes unintended behavior in execution

[Weddington, Eric]

> -----Original Message-----
> From: Weddington, Eric 
> Sent: Thursday, June 17, 2010 9:15 PM
> To: 'Wouter van Gulik'; address@hidden
> Subject: RE: [avr-libc-dev] LPM instructionsin optimized code 
> causes unintended behavior in execution
> 
>  
> 
> As a matter of fact.... (checking code and instruction set)
> 
> The code you have in the bug report shows:
> 5808:       f4 91           lpm     r31, Z+
> 
> Take a long hard look at the hex instruction. Reverse the bytes: 91 F4
> 
> The LPM instruction in the instruction set document (page 91) 
> shows this is Form 2 (ii) of the LPM instruction which is 
> "LPM, r, Z", which is without the plus sign. Therefore this 
> is not undefined. You've just rediscovered a different bug in 
> binutils.
> 

I forgot: Technically the bug cannot be pushed up to the binutils folks, 
because IIRC this is in the XMEGA patch to binutils. All of the XMEGA patches 
have not been submitted upstream yet, though we are planning on doing so. It 
*was* on the WinAVR bug list, but now it's on an internal list.

Sorry for the hassle.

Eric Weddington