zahiraam added a comment. In D121122#3402442 <https://reviews.llvm.org/D121122#3402442>, @aaron.ballman wrote:
> In D121122#3402334 <https://reviews.llvm.org/D121122#3402334>, @bjope wrote: > >> Hello. We've got some problem in our downstream tests after this patch and >> I'm trying to figure out how things are supposed to work. Maybe someone >> being part of this review knows. > > Sorry for the troubles! > >> Problem is that we have some libc verification suites that include test >> cases using `float_t`. But in math.h from for example newlib the type >> float_t isn't defined if FLT_EVAL_METHOD is set to -1. >> The standard says that float_t is implementation defined when >> FLT_EVAL_METHOD isn't 0/1/2. But I'm not quite sure how that is supposed to >> be handled (such as where to define float_t if not in math.h). > > The way I read the requirements in C2x 7.12p3 are that the types `float_t` > and `double_t` are always defined in `<math.h>`, but in the event > `FLT_EVAL_METHOD` isn't 0, 1, or 2, the implementation has to pick whatever > type makes the most sense for the underlying types. > >> One question is: If I have a piece of C99 code using float_t, is that code >> not allowed to be compiled using fast-math? > > The standard doesn't admit that fast math is a thing; it's up to the > implementations to define what their fast math extension does. > >> I guess it should be seen as with fast-math the float_t precision is >> unknown. But the type still has to be defined somewhere or else the frontend >> will complain about "unknown type name". But I'm not sure where this is >> supposed to be handled. > > I think it should still be handled in `<math.h>`. *I am not a C floating > point expert, so take this suggestion with a grain of salt*: I think it is > defensible to fallback to defining `float_t` as `float` and `double_t` as > `double` when the eval method is indeterminable. @andrew.w.kaylor may have > more nuanced thoughts here. Thanks for the answer @aaron.ballman. Looking at this https://godbolt.org/z/drhGEjvns i see that float_t is defined in math.h (if I remove the include it will fail). Not sure what version of libs godbolt is using, but I tend to agree that it should be defined in math.h too. But Andy will have a more definite answer. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D121122/new/ https://reviews.llvm.org/D121122 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
