Re: [hatari-devel] Issues with cache hits/misses?

[Douglas Little <doug694@xxxxxxxxxxxxxx>]

Hi,

If I bypass the "v1 >> .... * 8" line and do a return of the data immediately, emulation is nearly as fast as when 68030 cached is disabled.

But it seems that the right shift to extract the correct byte/word from the long word is taking a huge time (even with gcc -O3). Maybe some more recent cpu are better at doing right shift, but I would have expected it took only 1 cycle (in my case, it's an intel core 2 duo @ 3 GHz)

It might be due to the dynamically calculated shift size and the size of the type being shifted, resulting in the compiler just generating some unnecessarily pedantic code.

However such a trivial thing seems to be a strange source of performance drop on a modern PC. I'd suspect something else is going on...

D