Re: [avr-gcc-list] Compiler error creating ISR prologue?

[István]

Hi,
if I am not deluded by my memory, r1 permanently holds 0. Actually clr 
r1 is redundant.
István

2010-08-12 18:13 keltezéssel, Johannes Bauer írta:
> Hello group,
>
> I think I may have found a bug in the avr-gcc compiler. The created
> prologue looks like this with avr-gcc 4.3.4 and a XMega128A1 target:
>
> 000057b6 <__vector_83>:
>     57b6:       1f 92           push    r1
>     57b8:       0f 92           push    r0
>     57ba:       0f b6           in      r0, 0x3f        ; 63
>     57bc:       0f 92           push    r0
>     57be:       08 b6           in      r0, 0x38        ; 56
>     57c0:       0f 92           push    r0
>     57c2:       18 be           out     0x38, r1        ; 56
>     57c4:       09 b6           in      r0, 0x39        ; 57
>     57c6:       0f 92           push    r0
>     57c8:       19 be           out     0x39, r1        ; 57
>     57ca:       0b b6           in      r0, 0x3b        ; 59
>     57cc:       0f 92           push    r0
>     57ce:       1b be           out     0x3b, r1        ; 59
>     57d0:       11 24           eor     r1, r1
>
> This appears to be strange to me. The "clr r1" instruction should IMO
> be placed after the first "push r0" instruction. Otherwise, the
> RAMPD/X/Z registers may be initialized with random crap instead of 0
> as they should be.
>
> Kind regards,
> Johannes
>
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