[PATCH] D38554: Fixed ppc32 function relocations in non-pic mode

[vit9696 via Phabricator via llvm-commits]

vit9696 added a comment.

@hfinkel, that sounded like a good idea in the beginning, but after I implemented it by changing the condition to the following:

  bool Local = TM.shouldAssumeDSOLocal(*Mod, GV);
  // Do not use the PLT when explicitly told to do so
  if (!Local && GV && GV->isDeclarationForLinker()) {
    const Function *F = dyn_cast_or_null<Function>(GV);
    Local = F && F->hasFnAttribute(Attribute::NonLazyBind);
  }
  bool UsePlt = !Local && Subtarget.isTargetELF() && !isPPC64;

It did not quite work out. Consider the following example:

  unsigned long long fn1();
  unsigned fn2();
  
  int __start() {
    unsigned long long v1 = fn1();
    unsigned v2 = fn2();
    return v1 % v2;
  }

With -fno-plt and this patch added fn1 and fn2 would work just fine, however, v1 % v2 resolving to __umoddi3 would not, since GV would be null in the first place.

I am not sure if this can be handled without breaking shared builtins linkage, to be honest. So adding basic PLTREL support for lld might be easier after all since IFUNCs are already supported in LLVM and we cannot special case just the relocation model. I submitted a patch here: https://reviews.llvm.org/D39226. I can also submit the -fno-plt patch as well (for completeness) but I am afraid it will be of no real use due to builtins.


https://reviews.llvm.org/D38554