PC Lab 1

Session 1, x86 optimization:

C/C++: increase the execution speed for the code that reverses the order of the bits composing a 100 M esantioane of unsigned 32-bit (eg. 10111...11 -> 11..11101)

Expected/Presented techniques:

Grade 7/10: first implementation ~ 10 seconds

Grade 8/10: compiler optimized ~ 5 seconds

Grade 9/10: loop unrolling ( > 1s )

optimizing variables into registers ( > 1s )

Grade 10: bit-tricks 500 ms

Grade 10: 256-entry 8-bit table of 1 KB ~ 400 ms

Grade 10: 16-bit table of 64 k entries (256 KB) ~ 200 ms

32-bit table of 4 G entries (16 GB) ~ 66 ms