[avr-gcc-list] Re: WinAVR 20050214 (gcc 3.4.3) and optimizer bug.

[Vesa Jääskeläinen]

Joerg Wunsch wrote:
> As Vesa Jääskeläinen wrote:
>
> > I have been debugging why Ethernut brakes in certain situations with
> > gcc. And found an optimizer bug.

> I can't seem to find one.

Hmm... I still can :)

> > We can see that one compare is missing and this causes functional
> > change to code.
>
>
> Which one is missing do you think?  The full assembler code shows all
> of them:

In this clause:
        if (ppv && (*ppv != 0)) {

We are missing code for (ppv != 0), but code for *ppv != 0 is found. And
 if I pass NULL to this function it makes compare to incorrect memory
location.

If I compile it with -O0 or -O1 comparison is not omitted and it
generates working code.

--- snip ---

> Don't rely on annotated disassembled code.  In your case, it seems the
> optimizer moved parts of the conditionals into the function
> initialization, so it was not assigned to some line number in the
> debugging information.  For that reason, the annotator didn't tell you
> about it.
>
> At least from an eyeball review, the above assembler code (produced by
> GCC 3.4.3 for an ATmega128 target, in case it matters) looks identical
> to your C code to me.

Unfortunely I am unable to see your side of the story here. If you still
think that I am wrong here, please show where code of ppv != 0
comparison went.

Thanks,
Vesa Jääskeläinen