On 11/6/05, Paolo Carlini <[EMAIL PROTECTED]> wrote: > Richard Guenther wrote: > > We could just provide fallback libcalls in libgcc > Indeed, this is an option. Not one I can implement myself quickly, but I > think the idea of issuing a library call when the builtin is not > available was actually meant to enable this kind of solution. > > Can you work on it? > > - though usually you > > would want a fallback on a higher level to avoid too much overhead. > > > Well, we are talking about i386... But yes, that could make sense, for > example if you want to compile once both for i386 and i686 and obtain > decent performance everywhere. Consider, however, that currently we end > up doing a function call anyway, no inlining, so... > > So - can't you work with some preprocessor magic and a define, if > > the builtins are available? > > > I don't really understand this last remark of yours: is it an alternate > solution?!? Any preprocessor magic has to rely on a new preprocessor > builtin, in case, because there is no consistent, unequivocal way to > know whether the builtins are available for the actual target, we > already explored that some time ago, in our (SUSE) gcc-development list too.
Can you point me to some libstdc++ class/file where you use the builtins or other solution? Of course I meant having another builtin preprocessor macro. As the builtins are pretty low-level, somebody might provide a low-level workaround if they're missing, too, instead of having libcalls to libgcc (like for a freestanding environment like the kernel). So ultimately a preprocessor driven solution maybe the better one. Richard.
