majnemer added a comment. In https://reviews.llvm.org/D40023#933466, @asb wrote:
> In https://reviews.llvm.org/D40023#933464, @majnemer wrote: > > > So how does something like the following work: > > > > union U { float f; int i; }; > > void f(union U u); > > > > > > The flattening described in > > https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#hardware-floating-point-calling-convention > > makes sense for arrays and structs but I couldn't find where unions were > > described. > > > You're right that's not currently described - I have an issue tracking this > here: https://github.com/riscv/riscv-elf-psabi-doc/issues/24. Last time I > tried to check gcc behaviour it seemed that such cases would be passed > according to the integer calling convention, but I'd be happier if one of the > GCC devs would confirm. Should we have a test which tries to make sure our behavior matches GCC's? ISTM that floats in unions are always in GPRs (at least according to abicop). How are empty unions/arrays handled? Like a function which takes no args? abicop seemed upset when I asked it: >>> m.call([Union()]) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "~/majnemer/abicop/rvcc.py", line 186, in __init__ self.alignment = max(m.alignment for m in members) ValueError: max() arg is an empty sequence It'd also be good to have a test for bool and tests for bitfields. Am I correct that struct S { int x : 2; int y : 2; }; would get passed in two GPRs which were sign extended from 2 to 32? https://reviews.llvm.org/D40023 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
