Marcin 'Qrczak' Kowalczyk <qrczak@knm.org.pl> writes: > .L4: > testb %dl, %dl > jne .L3 > xorl %eax, %eax > .L3: > rep ; ret > > BTW, what is the "rep ; ret" in the last line? That works around a limitation in the Athlon branch predictor. In some cases it cannot predict a branch to ret, and adding the prefix avoids that. -Andi