On 3/2/11 3:20 PM, Walter Bright wrote:
dsimcha wrote:
== Quote from Walter Bright (newshou...@digitalmars.com)'s article
bearophile wrote:
Bekenn:
The use of ref introduces a level of indirection.
This is correct. But a minimally decent compiler must be able to
remove this
indirection where possible, like here, and produce efficient code.
Having the optimizer remove indirection is rarely possible in C or
C++, due to
aliasing.
I'm sure there are tons of nitty-gritty details in implementing
something like
this properly, but **in principle**, can't the compiler put a runtime
check in for
aliasing and select the code path based on whether aliasing is present
or not?
Essentially, you'd have two generated functions, one that handles the
aliasing
case and one that handles the no-aliasing case.
The check will cost you more than you win!
Often you stand to win a lot, albeit for simple functions (i.e. consider
memmove).
Andrei
