> On Sep 24, 2019, at 11:36 AM, Nat! via lldb-dev <lldb-dev@lists.llvm.org> > wrote: > > > > On 24.09.19 19:28, Jim Ingham wrote: >> We've had many requests to elide some classes of entries in backtraces - >> like to mirror the Xcode display I mentioned previously. Most of these >> requests don't depend on the functions being marked artificial. So if we're >> going to do this, something more general than just "marked artificial" -> >> elided anyway. >> >> Jim >> >> > > Yes. > > Having done a little further research... Artificial won't work for general > cases anyway, since it's restricted to inline code (for some reason) on gcc > and clang. I wonder why, since for a function the only real effect is to emit > DW_AT_artificial (AFAIK). The restriction seems arbitrary and DWARF wouldn't > mind.. But the compilers do, so it seems out anyway. > > DW_AT_trampoline isn't supported by llvm. As I read the description of > DW_AT_trampoline, its more like a hardcoded vector (a->b), so not useful for > cases like objc_msgSend, where you don't know the destination a priori. > > If I look at the DWARF spec, I don't see any other way to mark a function as > "boring". I still think this would be a good thing, as this would be useful > for other debuggers as well, which could instantly work. Also a lot of code > in the lldb Trampoline classes, for step-in and step-out could probably just > be removed.
I don't think that is right for "step-in". As you said above, in the classic example of a trampoline: objc_msgSend you can't statically know the destination. So the DWARF can't help resolve this; you would still need to do the work the lldb trampoline classes do at runtime. step-out past trampolines could just "keep stepping past boring functions". There's no need to support this for ObjC - at least the Apple & NeXT versions - since the dispatch function is a tail call function. But we do do something like for Swift. But that part is very little code compared to figuring how to step in correctly. Jim > > Ciao > Nat! > > _______________________________________________ > lldb-dev mailing list > lldb-dev@lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev _______________________________________________ lldb-dev mailing list lldb-dev@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
