Hi David, Have you had a chance to take a look at the avr target bugs in the GCC Bugzilla database? This might have already been submitted, but if not, could you submit a bug to the GCC project? If you do this, please put my email address in the CC list.
Thanks, Eric Weddington > -----Original Message----- > From: avr-gcc-list-bounces+eric.weddington=atmel....@nongnu.org > [mailto:avr-gcc-list-bounces+eric.weddington=atmel....@nongnu.org] On > Behalf Of David Kopf > Sent: Tuesday, December 21, 2010 8:02 AM > To: avr-gcc-list@nongnu.org > Subject: [avr-gcc-list] Bug with -Os with constant multiplier of 3? > > Hi, > > Using WinAVR avr-gcc 4.3.0 and 4.3.3, compiling 3*<uint8_t> with -Os calls > __mulhi3 instead of the optimized *2+1 when no hardware > multiply is present. O1,O2,O3 does it right: > > Target: ATTiny85 > > > uint8_t rssi; //r24 > > -O1 -O2 -O3 > > rssi=3*rssi; > > aa: 28 2f mov r18, r24 > > ac: 22 0f add r18, r18 > > ae: 28 0f add r18, r24 > > > > > -Os > > rssi=3*rssi; > > ae: 90 e0 ldi r25, 0x00 ; 0 > > b0: 63 e0 ldi r22, 0x03 ; 3 > > b2: 70 e0 ldi r23, 0x00 ; 0 > > b4: 40 d0 rcall .+128 ; 0x136<__mulhi3> > > > > > > _______________________________________________ > AVR-GCC-list mailing list > AVR-GCC-list@nongnu.org > http://lists.nongnu.org/mailman/listinfo/avr-gcc-list _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
