On 25/07/12 09:37, Walter Bright wrote:
On 7/24/2012 11:46 PM, Dmitry Olshansky wrote:
It's pc => address because one can first preprocess all of byte code
doing
opcode => address rewrites. But you can't do it unless taking address
of labels
is possible.
All right, that's the piece that was missing.
I suppose it is possible for the compiler to recognize that the
opcode=>address array is invariant, and optimize it out, but that would
be a novel optimization. I don't know how hard it would be.
> Done: http://d.puremagic.com/issues/show_bug.cgi?id=8431
Thanks!
Another interesting optimization with "final switch" would be if each
case has about the same code length.
final switch(x) {
case C1: ...
case C2: ...
case C3: ...
case C4: ...
}
then if &(case c2) - &(case C1) == &(case C3) - &(case C2)
change it to
goto (&case C1) + x *( &(case c2) - &(case C1) );
so that there is no lookup table, just a multiply.
