[Bug optimization/11181] [3.3 only][avr-gcc] Optimization of "uchar/xor/and/single_bit" produced wrong code.

[ehrhardt at mathematik dot uni-ulm dot de]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11181



------- Additional Comments From ehrhardt at mathematik dot uni-ulm dot de  2003-07-28 16:42 -------
Subject: Re:  [avr-gcc] Optimization of "uchar/xor/and/single_bit" produced wrong code.

On Mon, Jul 28, 2003 at 04:20:58PM -0000, pinskia at physics dot uc dot edu wrote:
> It looks like the mainline (20030728) is still broken with -Os
> (but I do not read avr asm.):

I've never seen an avr either ;-) But now gcc at least emmits an eor
after the call which is definitely a progression wrt. the assembly
in the audit trail.

> .L2:
>         rcall f
>         ldi r25,lo8(1)
>         eor r25,r24
>         sbrs r25,0
>         rjmp .L2

I found an avr tutorial at

   http://www.avr-asm-tutorial.net/avr_en/beginner/index.html

and this tells me that sbrs skips the next instruction if Bit 0 in r25
ist set. I.e. this code looks correct to me.

    regards  Christian