[gentoo][use-flags] Про полезность отдельных

$ gcc -c -Q -O2 --help=optimizers |grep falign-loops
  -falign-loops               		[выключено]

core2
               Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3 instruction set support.

 gcc -c -Q -march=core2 --help=target | grep msse
  -msse                       		[выключено]
  -msse2                      		[выключено]
  -msse2avx                   		[выключено]
  -msse3                      		[выключено]
  -msse4                      		[выключено]
  -msse4.1                    		[выключено]
  -msse4.2                    		[выключено]
  -msse4a                     		[выключено]
  -msseregparm                		[выключено]

gcc -c -Q -march=core2 --help=target | grep mmx
  -mmmx                       		[выключено]

-O2 turns on all optimization flags specified by -O.  It also turns on the following optimization flags: 
... -falign-loops .....

gcc -c -Q -O2 --help=optimizers |grep falign-loops
  -falign-loops               		[выключено]