On Mon, Feb 8, 2016 at 2:55 PM, Richard Smith <rich...@metafoo.co.uk> wrote: > On Mon, Feb 8, 2016 at 2:49 PM, H.J. Lu <hjl.to...@gmail.com> wrote: >> On Mon, Feb 8, 2016 at 2:42 PM, Richard Smith <rich...@metafoo.co.uk> wrote: >>> Do we really need an 'empty type' special case? >>> >>> The x86_64 psABI already seems clear that empty types with size <= 16 >>> are not passed at all. Following the algorithm in section 3.2.3, each >>> eightbyte is classified as NO_CLASS, and thus is not passed. So the >>> proposed change would only affect the behavior of types larger than 16 >>> bytes that contain no data. It doesn't seem worth breaking ABI to more >>> efficiently pass those. >>> >> >> Clang isn't consistent between ia32 and x86-64. GCC isn't compatible >> with clang. My proposal will make GCC and clang compatible. It also >> makes GCC and clang behave the same on both ia32 and x86-64. > > OK, but if the ABI is already saying what we want, and the only > problem is that GCC and Clang don't conform to the ABI in some cases, > then we just need to fix the compilers and not the ABI. Which cases do > we think the existing ABI rule misclassifies?
I want to make it explicit in psABIs to avoid any possible confusion and x86-64 classification rules don't apply to ia32. -- H.J. _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
