9 Sep
2016
9 Sep
'16
8:43 a.m.
I sent a similar message some time ago, but I haven't
seen it appear in the mailing list, so here goes again.
Apologies if it ends up as a duplicate.
After about 30 years of C, there are only three things
I would have liked
to see:
1. Computed goto
...
Computed goto's are good for interpreters.
A computed goto is an optimized switch, and that optimization
goes back to the original C compiler. Mostly driven by
considerations of size and speed of the Unix kernel, Dennis
quite early on taught the compiler to choose among three
compilation strategies for a switch: a chain of comparisons,
a tree of comparisons, or a computed goto, depending on the
number and density of alternatives.
The compilation of the system-call dispatch table was
a perfect example of "good for interpreters."
I have always assumed that other mainline compilers behave
similarly, but I have no solid knowledge about that.
doug