[llvm] r271066 - Start using shouldAssumeDSOLocal on ARM.

[Steven Wu via llvm-commits]

Thanks!

> On Aug 24, 2016, at 11:20 AM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> 
> It should be checking the file format. I will fix that after lunch. Thanks.
> 
> 
> On Aug 24, 2016 1:52 PM, "Steven Wu" <stevenwu at apple.com <mailto:stevenwu at apple.com>> wrote:
> Hi Rafael
> 
> I run into a problem for this commit. See comment below.
> 
> > On May 27, 2016, at 3:41 PM, Rafael Espindola via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
> >
> > Author: rafael
> > Date: Fri May 27 17:41:51 2016
> > New Revision: 271066
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=271066&view=rev <http://llvm.org/viewvc/llvm-project?rev=271066&view=rev>
> > Log:
> > Start using shouldAssumeDSOLocal on ARM.
> >
> > Given where this is used it should be a nop.
> >
> > Modified:
> >    llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp
> >
> > Modified: llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp
> > URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp?rev=271066&r1=271065&r2=271066&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp?rev=271066&r1=271065&r2=271066&view=diff>
> > ==============================================================================
> > --- llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp (original)
> > +++ llvm/trunk/lib/Target/ARM/ARMSubtarget.cpp Fri May 27 17:41:51 2016
> > @@ -22,6 +22,7 @@
> > #include "Thumb1FrameLowering.h"
> > #include "Thumb1InstrInfo.h"
> > #include "Thumb2InstrInfo.h"
> > +#include "llvm/CodeGen/Analysis.h"
> > #include "llvm/CodeGen/MachineRegisterInfo.h"
> > #include "llvm/IR/Attributes.h"
> > #include "llvm/IR/Function.h"
> > @@ -273,40 +274,19 @@ bool ARMSubtarget::isAAPCS16_ABI() const
> >   return TM.TargetABI == ARMBaseTargetMachine::ARM_ABI_AAPCS16;
> > }
> >
> > -
> > -/// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
> > +/// true if the GV will be accessed via an indirect symbol.
> > bool
> > ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
> >                                  Reloc::Model RelocM) const {
> > -  if (RelocM == Reloc::Static)
> > -    return false;
> > -
> > -  bool isDef = GV->isStrongDefinitionForLinker();
> > +  if (!shouldAssumeDSOLocal(RelocM, TargetTriple, *GV->getParent(), GV))
> > +    return true;
> >
> > -  if (!isTargetMachO()) {
> > -    // Extra load is needed for all externally visible.
> > -    if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
> > -      return false;
> > +  // 32 bit macho has no relocation for a-b if a is undefined, even if b is in
> > +  // the section that is being relocated. This means we have to use o load even
> > +  // for GVs that are known to be local to the dso.
> > +  if (isTargetDarwin() && RelocM == Reloc::PIC_ &&
> > +      (GV->isDeclarationForLinker() || GV->hasCommonLinkage()))
> Is there any specific reason using isTargetDarwin() instead of isTargetMachO()? This seems like a general limitation for MachO which is not specific to Darwin. When I compiling embedded architecture for MachO (armv7em), my target is not Darwin but it is still MachO (default triple is thumbv7em-apple-unknown-macho). I will get error like:
> fatal error: error in backend: symbol '*' can not be undefined in a subtraction expression
> 
> Thanks
> 
> Steven
> 
> >     return true;
> > -  } else {
> > -    // If this is a strong reference to a definition, it is definitely not
> > -    // through a stub.
> > -    if (isDef)
> > -      return false;
> > -
> > -    // Unless we have a symbol with hidden visibility, we have to go through a
> > -    // normal $non_lazy_ptr stub because this symbol might be resolved late.
> > -    if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
> > -      return true;
> > -
> > -    if (RelocM == Reloc::PIC_) {
> > -      // If symbol visibility is hidden, we have a stub for common symbol
> > -      // references and external declarations.
> > -      if (GV->isDeclarationForLinker() || GV->hasCommonLinkage())
> > -        // Hidden $non_lazy_ptr reference.
> > -        return true;
> > -    }
> > -  }
> >
> >   return false;
> > }
> >
> >
> > _______________________________________________
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> 
> 

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