[LLVMdev] rol/ror llvm instruction set

[Bill Wendling]

On Tue, Feb 3, 2009 at 4:27 PM, Kasra <kasra_n500 at yahoo.com> wrote:
>
> You could not be more right. However, rotations was not widely implemented on machines when C and C++ was evolved. Python and other high level languages are just too high level (hence, inefficient) to have such semantics.
>
> The argument sounds fine, however, remember that the number of platforms that don't implement an instruction could not be a point of simile.
>
> Say we have 100 Linux distribution that do not have a certain feature, we can't conclude that that feature is not a common feature. We should consider the mainstream Linux distributions (and even if we may the giant of current desktops Windows).
>
> Since x86 is about (if I am not wrong) 95% of the desktop PC's we could say rotation is implemented on most of the machines where LLVM will be running.
>
> I bet out of the people who are reading/following this thread majority are running under x86 any way :D
>
> So I guess what I am saying is rotations is very wide spread except that there are many machines out there that do not implement it however, the number of machine that do is far grater.
>
I would not bet against you on that. :-) And, truth be told, it
probably wouldn't be too much of a hardship for platforms that don't
support rotates to lower them. But it's currently just extra work that
we don't need until we have a reason to add the rotate instructions.

-bw