On Mon, Apr 26, 2021 at 09:51:50AM -0600, Jeff Law wrote: > > On 4/24/2021 8:26 AM, Michael Catanzaro wrote: > > On Fri, Apr 23 2021 at 08:01:03 PM +0200, Jakub Jelinek > > <jakub@xxxxxxxxxx> wrote: > > > I'll be probably repeating myself, but the two compilers are known to be > > > ABI incompatible in very important ways, none of the > > > https://bugs.llvm.org/buglist.cgi?quicksearch=42439%2C19909%2C44228%2C12207 > > > > > > bugs have been touched since last time this was discussed and I'm > > > not aware > > > of any ABI compatibility testing between the two compilers. > > > So if some library packages switch compilers and programs using those > > > libraries don't or vice versa, this proposal has quite high risks of > > > introducing hard to debug debugs. > > > > Perhaps this proposal should be revisited in the future when there are > > fewer scary ABI bugs. > > That's not really a scary ABI bug. There's disagreement about a fairly > unusual case involving extension of 8 bit arguments and some issues with 128 There is disagreement on passing all 8-bit and 16-bit arguments by value on x86_64, which in many cases works just by pure luck because GCC often emits the extension even on the caller side where it is not mandated by the psABI, while LLVM relies on an extension the psABI doesn't guarantee. Several packages already ran into this in the past, I don't think we can ignore that one. The va_arg passing bug for __int128 is less important, sure, most packages don't use 128-bit integers and if they do, they rarely pass it through va_arg. But having 8-bit and 16-bit arguments on ABI boundaries is very common. That is one thing and the other one is that the interoperability testing between the two compilers wasn't really performed, so besides those known bugs there can be unknown ones. Jakub _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
