Klaus, I'm not sure if my previous answer didn't make it through or was just missed, but I believe your problem is related to this GCC bug: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70435 -Anton On Mon, Apr 12, 2021 at 5:14 AM Klaus Rudolph <lts-rudolph@xxxxxx> wrote: > Am 12.04.21 um 13:53 schrieb Matthijs Kooijman: > >>> - figure out, where the special handling of the __vector_10 seems to > >>> happen, and why it is not happening in the class template case. This > >>> might help diagnose if and where to fix it within the compiler. > >> > >> That is compiler internals... yes, if it is a compiler bug, it is the > >> way to have a solution. But in that case, it seems to be a generic > >> problem for gcc as attributes are not assigned to any templated class > >> member functions. No idea if this is related to the target ( avr ) or > >> generic for all platforms. But I never did any change inside the > >> compiler. Any help is welcome! > > > > My suspiciou would be that this is a generic gcc problem, where the > > "asm" attribute is not honoured for template functions. It probably also > > makes some sense, since a template is intended to be instantiated > > multiple times, and each instantiation gets a name that is generated > > based on (I believe) the template arguments passed, so I suspect that > > the "generate a name for this template instantiation" code doesn't look > > at the asm attribute. > > > > Also note that *if* it would, then each instantiation would use the same > > name and multiple instanations would result in duplicate symbols. If you > > would bring this up as a gcc bug, I wouldn't be surprised that it would > > be closed as wontfix for this reason. > > I disagree as a template "always" would be instantiated multiple times. > And even if it would be, the linker will fire a error message, as it > sees multiple definitions. So there is no "general" problem in > "renaming" a templated function. It simply *can* work. > > But it looks that not only the "renaming" stuff did not work, all the > flags are not handled with the templated function. Looks like that the > asm declaration did not find its target :-) > > > > > Another workaround that I think hasn't been suggested yet, would be to > > just define a global `__vector_10` function and from that just call your > > templated static member. > > That is the classical way "we" all work. And it optimizes well in that > case as the code from the static templated member is fully inlined. But > it is still a workaround and it simply breaks standard c++ coding. Yes, > we can write C with classes, but I simply dislike :-) > > > Combined with the `always_inline` attribute, > > you can ensure that the call is inlined and there is no runtime overhead > > (with LTO, this probably already happens when there's just a single call > > to the member). > > It already optimizes well in O2 if templated member function and free > handler definition is in same translation unit. > > Klaus > > >
