On Thursday, 6 February 2014 at 11:44:34 UTC, Michel Fortin wrote:
That thread about buildPath started like this: "Walter and I
were talking about eliminating the surreptitious allocations in
buildPath". But reference counting will do nothing to eliminate
surreptitious allocations. It can't be that problem you're
trying to address.
I think stuff like buildPath just shows how the language should
be geared more towards compiler optimizations of allocation if
performance is a real goal.
The efficient thing to do is to optimize a string concat into a
stack allocation (alloca) if it is a throw-away, and just change
the stack frame upon return, with some heuristics and alternative
execution paths in order to avoid running out of stack space.
E.g.
a(){
return buildPath(...) ~ "!";
}
Compiles to:
a:
call buildPath(...)
alloca(size_to_endof_path_returned_by_buildPath+1)
*someaddr = '!'
return (stackbufferstart,length)
buildPath:
stackbuffer=alloca(sum_of_lengths)
copy...
return tuple(stackbufferstart,length)
