[lld] r298792 - Add comments and return early.

[Rui Ueyama via llvm-commits]

As Davide guessed, that means interposable or preemptible. I'll update the
comment to use preemptible, as the term is used throughout this file.

On Sat, Mar 25, 2017 at 11:16 PM, Davide Italiano <davide at freebsd.org>
wrote:

> On Sat, Mar 25, 2017 at 10:21 PM, Sean Silva via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
> > what does "non-interruptable" mean in this context? in the same segment?
> >
>
> Unless I'm reading the context incorrectly, it's a synonym for not
> preemptible at runtime.
> In case my guess is right, I really dislike the word `interruptible`
> because is such an overloaded word in systems.
> I'd rather use `interposable` or `preemptible` (to the best of my
> knowledge they're all synonyms in ELF, but please double
> check/confirm).
>
> > On Mar 25, 2017 9:32 PM, "Rui Ueyama via llvm-commits"
> > <llvm-commits at lists.llvm.org> wrote:
> >>
> >> Author: ruiu
> >> Date: Sat Mar 25 22:20:30 2017
> >> New Revision: 298792
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=298792&view=rev
> >> Log:
> >> Add comments and return early.
> >>
> >> Modified:
> >>     lld/trunk/ELF/Relocations.cpp
> >>
> >> Modified: lld/trunk/ELF/Relocations.cpp
> >> URL:
> >> http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/
> Relocations.cpp?rev=298792&r1=298791&r2=298792&view=diff
> >>
> >> ============================================================
> ==================
> >> --- lld/trunk/ELF/Relocations.cpp (original)
> >> +++ lld/trunk/ELF/Relocations.cpp Sat Mar 25 22:20:30 2017
> >> @@ -312,6 +312,15 @@ static bool isRelExpr(RelExpr Expr) {
> >>                          R_PAGE_PC, R_RELAX_GOT_PC>(Expr);
> >>  }
> >>
> >> +// Returns true if a given relocation can be computed at link-time.
> >> +//
> >> +// For instance, we know the offset from a relocation to its target at
> >> +// link-time if the relocation is PC-relative and refers a
> >> +// (non-interruptible) function in the same executable. This function
> >> +// will return true for such relocation.
> >> +//
> >> +// If this function returns false, that means we need to emit a
> >> +// dynamic relocation so that the relocation will be fixed at
> load-time.
> >>  template <class ELFT>
> >>  static bool
> >>  isStaticLinkTimeConstant(RelExpr E, uint32_t Type, const SymbolBody
> >> &Body,
> >> @@ -331,16 +340,19 @@ isStaticLinkTimeConstant(RelExpr E, uint
> >>
> >>    if (isPreemptible(Body, Type))
> >>      return false;
> >> -
> >>    if (!Config->Pic)
> >>      return true;
> >>
> >> +  // For the target and the relocation, we want to know if they are
> >> +  // absolute or relative.
> >>    bool AbsVal = isAbsoluteValue<ELFT>(Body);
> >>    bool RelE = isRelExpr(E);
> >>    if (AbsVal && !RelE)
> >>      return true;
> >>    if (!AbsVal && RelE)
> >>      return true;
> >> +  if (!AbsVal && !RelE)
> >> +    return Target->usesOnlyLowPageBits(Type);
> >>
> >>    // Relative relocation to an absolute value. This is normally
> >> unrepresentable,
> >>    // but if the relocation refers to a weak undefined symbol, we allow
> it
> >> to
> >> @@ -350,16 +362,14 @@ isStaticLinkTimeConstant(RelExpr E, uint
> >>    // Another special case is MIPS _gp_disp symbol which represents
> offset
> >>    // between start of a function and '_gp' value and defined as
> absolute
> >> just
> >>    // to simplify the code.
> >> -  if (AbsVal && RelE) {
> >> -    if (Body.isUndefined() && !Body.isLocal() &&
> Body.symbol()->isWeak())
> >> -      return true;
> >> -    error(S.getLocation<ELFT>(RelOff) + ": relocation " +
> toString(Type)
> >> +
> >> -          " cannot refer to absolute symbol '" + toString(Body) +
> >> -          "' defined in " + toString(Body.File));
> >> +  assert(AbsVal && RelE);
> >> +  if (Body.isUndefined() && !Body.isLocal() && Body.symbol()->isWeak())
> >>      return true;
> >> -  }
> >>
> >> -  return Target->usesOnlyLowPageBits(Type);
> >> +  error(S.getLocation<ELFT>(RelOff) + ": relocation " +
> toString(Type) +
> >> +        " cannot refer to absolute symbol '" + toString(Body) +
> >> +        "' defined in " + toString(Body.File));
> >> +  return true;
> >>  }
> >>
> >>  static RelExpr toPlt(RelExpr Expr) {
> >>
> >>
> >> _______________________________________________
> >> llvm-commits mailing list
> >> llvm-commits at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
> >
>
> --
> Davide
>
> "There are no solved problems; there are only problems that are more
> or less solved" -- Henri Poincare
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170326/95600370/attachment.html>