Re: [avr-gcc-list] Bug in *rotlsi3 insns?

[Georg-Johann Lay]

Georg-Johann Lay schrieb:
> Hi, im just browsing avr.md in trunk and stumbled over some new patterns 
> that implement rotlsi3.
>
> IMHO, they are buggy. But I have no testcase to make it explicit.

Consider this test case:

unsigned long rotl (int dummy, unsigned long x)
{
    return (x << 8) | (x >> 24);
}

Compile with, e.g.
   avr-gcc -mmcu=atmega8 -S -Os -fno-split-wide-types
to get

rotl:
/* prologue: function */
/* frame size = 0 */
        mov r22,r23
        mov r23,r20
        mov r24,r21
        mov r25,r22
/* epilogue start */
        ret

This will map 0x33221100 to 0x33110033 instead of to 0x22110033

Georg-Johann