[llvm] r255258 - Avoid undefined behavior when vector is empty.

[David Blaikie via llvm-commits]

Yeah, don't mind me - I think I was probably jetlagged and/or reading your
patch backwards, etc... carry on.

On Sun, Dec 20, 2015 at 8:41 PM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:

> Sorry, but I don't see toArrayRef anywhere.
>
> Cheers,
> Rafael
>
>
> On 14 December 2015 at 19:38, David Blaikie <dblaikie at gmail.com> wrote:
> > Ah, I just hit that myself while working on the type units in llvm-dwp.
> >
> > SetVector does have toArrayRef which is probably the better option than
> what
> > you have (what you have there would be UB if the container is empty, for
> > example).
> >
> > But yeah, I wouldn't mind if SetVector just had an "operator
> ArrayRef<T>".
> > That seems reasonable, unambiguous, obvious goodness.
> >
> > On Tue, Dec 15, 2015 at 5:27 AM, Rafael Espíndola
> > <rafael.espindola at gmail.com> wrote:
> >>
> >> On 13 December 2015 at 19:13, David Blaikie <dblaikie at gmail.com> wrote:
> >> >
> >> >
> >> > On Thu, Dec 10, 2015 at 8:35 AM, Rafael Espindola via llvm-commits
> >> > <llvm-commits at lists.llvm.org> wrote:
> >> >>
> >> >> Author: rafael
> >> >> Date: Thu Dec 10 10:35:06 2015
> >> >> New Revision: 255258
> >> >>
> >> >> URL: http://llvm.org/viewvc/llvm-project?rev=255258&view=rev
> >> >> Log:
> >> >> Avoid undefined behavior when vector is empty.
> >> >>
> >> >> Found by ubsan.
> >> >>
> >> >> Modified:
> >> >>     llvm/trunk/include/llvm/ADT/SetVector.h
> >> >>     llvm/trunk/lib/Linker/LinkModules.cpp
> >> >>
> >> >> Modified: llvm/trunk/include/llvm/ADT/SetVector.h
> >> >> URL:
> >> >>
> >> >>
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SetVector.h?rev=255258&r1=255257&r2=255258&view=diff
> >> >>
> >> >>
> >> >>
> ==============================================================================
> >> >> --- llvm/trunk/include/llvm/ADT/SetVector.h (original)
> >> >> +++ llvm/trunk/include/llvm/ADT/SetVector.h Thu Dec 10 10:35:06 2015
> >> >> @@ -58,6 +58,8 @@ public:
> >> >>      insert(Start, End);
> >> >>    }
> >> >>
> >> >> +  ArrayRef<T> getArrayRef() const { return vector_; }
> >> >> +
> >> >>    /// \brief Determine if the SetVector is empty or not.
> >> >>    bool empty() const {
> >> >>      return vector_.empty();
> >> >>
> >> >> Modified: llvm/trunk/lib/Linker/LinkModules.cpp
> >> >> URL:
> >> >>
> >> >>
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Linker/LinkModules.cpp?rev=255258&r1=255257&r2=255258&view=diff
> >> >>
> >> >>
> >> >>
> ==============================================================================
> >> >> --- llvm/trunk/lib/Linker/LinkModules.cpp (original)
> >> >> +++ llvm/trunk/lib/Linker/LinkModules.cpp Thu Dec 10 10:35:06 2015
> >> >> @@ -772,8 +772,7 @@ bool ModuleLinker::run() {
> >> >>        Internalize.insert(GV->getName());
> >> >>    }
> >> >>
> >> >> -  if (Mover.move(SrcM,
> >> >> -                 makeArrayRef(&*ValuesToLink.begin(),
> >> >> ValuesToLink.size()),
> >> >
> >> >
> >> > Isn't vector already implicitly convertible to ArrayRef? (I guess
> >> > there's
> >> > something else at work heer - 'move' is a function template & has
> weird
> >> > arg
> >> > deduction issues? something else?)
> >>
> >> ValuesToLink is a SetVector which is not implicitly convertible to
> >> ArrayRef. Should it be?
> >>
> >> Cheers,
> >> Rafael
> >
> >
>
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