Bernd Schmidt <bschm...@redhat.com> writes: > On 11/09/2015 03:57 PM, Richard Sandiford wrote: > >> I'm not sure what you mean by "fix" though. I don't think we can change >> any of the constraints above. > > I don't see why they couldn't be relaxed. What's stopping us from > defining some builtins independently of the frontends, and don't all > languages except Fortran use the normal builtins.def anyway?
I think the problem isn't so much with the functions that we define ourselves as those that simply mirror a standard library function. We can't assume that all the libm functions exist. It's also valid for the implementation to add target-specific attributes on top of what the standard says (e.g. "nomips16" on MIPS). So if a call starts out as a call to sinf and we treat it as a call to __builtin_sinf for optimisation purposes, there is always conceptually an underlying "physical" sinf function. We also can't convert calls to __builtin_sin to calls to __builtin_sinf without proof that a sinf definition exists (not guaranteed for C90). > Also - if you can have an internal function without a fndecl, why > wouldn't it work to allow that for builtins as well? But this is > probably moot since I can now see a little more clearly what you want > to do. I think that's the defining characteristic of builtins vs. internal functions though. built-in functions are directly callable by source code and have a defined function signature. Internal functions are not directly callable by source code and have a flexible function signature. There are cases where this difference doesn't matter, which is why the combined_fn enum seemed like a good idea. But I don't think we can do away with the distinction entirely. >> The main goal is to allow functions to be vectorised simply by defining >> the associated optab. > > Ok. So these internal functions would support arbitrary modes like > V[1248][SDX]F etc., unlike the builtins? Yeah. They also never set errno. > That wasn't entirely clear from the patches I looked at, it seemed > like you were just duplicating every builtin as an internal function > (something to which I would have objected). Yeah, sorry about that. I'll post the patches shortly. Thanks, Richard
