[llvm-commits] [llvm] r71717 - /llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp

[Dale Johannesen]

On May 14, 2009, at 12:57 AMPDT, Duncan Sands wrote:

> Hi Dale,
>
>> +/// findGlobalVariableBase - Recurse into a ConstantExpr to find  
>> the underlying
>> +/// GlobalVariable, if there is one.
>> +static GlobalVariable* findGlobalVariableBase(ConstantExpr* CE) {
>> +  if (isa<GlobalVariable>(CE))
>> +    return dyn_cast<GlobalVariable>(CE);
>> +  if (CE->getOpcode()==Instruction::GetElementPtr ||
>> +      CE->getOpcode()==Instruction::BitCast) {
>> +    if (isa<GlobalVariable>(CE->getOperand(0)))
>> +      return dyn_cast<GlobalVariable>(CE->getOperand(0));
>> +    if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(CE- 
>> >getOperand(0)))
>> +      return findGlobalVariableBase(CE2);
>> +  }
>> +  return NULL;
>> +}
>
> this looks very similar to what CE->getUnderlyingObject() does.

Sure does.  Thanks, I thought that functionality must be there  
somewhere.  Rewritten appropriately.

>> +        GlobalVariable* GV = dyn_cast<GlobalVariable>(I- 
>> >getOperand(0));
>> +        if (GV && GV->hasExternalWeakLinkage())
>> +          return false;
>
> How about adding an "address of this global value may be null"  
> method to
> GlobalValue (which would currently just check the linkage type) and  
> use
> that instead?

What other possibilities are you thinking of?