27 Sep
2000
27 Sep
'00
1:53 a.m.
On Tue, 26 Sep 2000, Sean 'Shaleh' Perry wrote:
gcc -Wall -m486 -g -O -DHAVE_CONFIG_H -DFPM_INTEL -c -o fixed.o fixed.c
Even with --enable-speed, -O is the most used for Intels. Why is this?
Because the C code is already carefully written with the operation flow for the best possible performances (loops were unrolled by hand only where it should be, etc). When -O2 (or hier) is used, gcc tries to be smarter than it should and actually produces worse output than with -O. This isn't generally true for many programs but it is for this particular application.
Nicolas