> -----Original Message----- > From: > [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > org] On Behalf Of Weddington, Eric > Sent: Wednesday, July 23, 2008 11:18 AM > To: Andy H; AVR-GCC > Subject: RE: [avr-gcc-list] Can someone benchmark this option please > > > > > -----Original Message----- > > From: > > [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] > > org] On Behalf Of Andy H > > Sent: Tuesday, July 22, 2008 6:40 PM > > To: AVR-GCC > > Subject: [avr-gcc-list] Can someone benchmark this option please > > > > Hi, > > > > I have noted problem where gcc is optimizing if-then-else > > constructs - > > with disastrous results. For example: > > > > if (a >= 0) > > return 8; > > else > > return 0; > > > > (This is now reported as bug.) > > > > Can folks try the following gcc option > > > > -fno-if-conversion > > > > on their own code at -Os optimization, and see if this produce > > better/worse or same code? This will help figure if the whole pass > > should be skipped - or whether it still contains useful > optimizations. > > > > Hi Andy, > > I tried it on the BC100 Kit code for gcc, which uses these options: > > -mmcu=attiny861 > -gdwarf-2 > -Os > -funsigned-char > -funsigned-bitfields > -fpack-struct > -fshort-enums > -Wall > -Wstrict-prototypes > -std=gnu99 > -ffunction-sections > -fno-inline-small-functions > -fno-split-wide-types > > When I added -fno-if-conversion, there was no change in code > size: 5588 bytes.
I also tried it on the Butterfly Kit code for gcc. It saved a whopping 2 bytes: Baseline: 13876 bytes With -fno-if-conversion flag: 13874 bytes. Eric _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
