Compiler gcc 4.6.1
Flags -O3 -march=core2
Result 2097152.000000

real	0m34.570s
user	0m33.389s
sys	0m0.015s

Compiler clang
Flags -O3 -march=core2
Result 2097152.000000

real	1m55.302s
user	1m51.653s
sys	0m0.045s

Compiler gcc 4.6.1 vector extensions, size 8
Flags -O3 -march=core2
Result 2097152.000000

real	4m30.960s
user	4m17.021s
sys	0m0.128s

Compiler clang vector extensions, size 8
Flags -O3 -march=core2
Result 2097152.000000

real	0m32.967s
user	0m31.311s
sys	0m0.032s

Compiler gcc 4.6.1 vector extensions, size 4
Flags -O3 -march=core2
Result 2097152.000000

real	0m34.613s
user	0m32.931s
sys	0m0.150s

Compiler clang vector extensions, size 4
Flags -O3 -march=core2
Result 2097152.000000

real	0m32.967s
user	0m31.584s
sys	0m0.053s

Compiler gcc 4.6.1 vector extensions, size 4
Flags -O3 -march=core2 -msse2 -ffast-math
Result 2097152.000000

real	0m33.740s
user	0m31.948s
sys	0m0.020s

Compiler gcc 4.6.1 vector extensions, size 4
Flags -O3 -march=core2 -msse3 -ffast-math
Result 2097152.000000

real	0m33.417s
user	0m31.968s
sys	0m0.048s