[llvm-commits] [llvm] r50840 - /llvm/trunk/lib/Analysis/ConstantFolding.cpp

[Bill Wendling]

Hey Chris,

> --- llvm/trunk/lib/Analysis/ConstantFolding.cpp (original)
> +++ llvm/trunk/lib/Analysis/ConstantFolding.cpp Wed May  7 23:54:43  
> 2008
> @@ -122,25 +122,32 @@
>                                          const Type *ResultTy,
>                                          const TargetData *TD) {
>   Constant *Ptr = Ops[0];
> -  if (!cast<PointerType>(Ptr->getType())->getElementType()- 
> >isSized())
> +  if (!TD || !cast<PointerType>(Ptr->getType())->getElementType()- 
> >isSized())
>     return 0;
>
> -  if (TD && Ptr->isNullValue()) {
> -    // If this is a constant expr gep that is effectively computing  
> an
> -    // "offsetof", fold it into 'cast int Size to T*' instead of  
> 'gep 0, 0, 12'
> -    bool isFoldableGEP = true;
> -    for (unsigned i = 1; i != NumOps; ++i)
> -      if (!isa<ConstantInt>(Ops[i])) {
> -        isFoldableGEP = false;
> -        break;
> -      }
> -    if (isFoldableGEP) {
> -      uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
> -                                             (Value**)Ops+1,  
> NumOps-1);
> -      Constant *C = ConstantInt::get(TD->getIntPtrType(), Offset);
> -      return ConstantExpr::getIntToPtr(C, ResultTy);
> -    }
> +  uint64_t BasePtr = 0;
> +  if (!Ptr->isNullValue()) {
> +    // If this is a inttoptr from a constant int, we can fold this  
> as the base,
> +    // otherwise we can't.
> +    if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
> +      if (CE->getOpcode() == Instruction::IntToPtr)
> +        if (ConstantInt *Base = dyn_cast<ConstantInt>(CE- 
> >getOperand(0)))
> +          BasePtr = Base->getZExtValue();
> +
> +    if (BasePtr == 0)
> +      return 0;
>   }
> +
> +  // If this is a constant expr gep that is effectively computing an
> +  // "offsetof", fold it into 'cast int Size to T*' instead of 'gep  
> 0, 0, 12'
> +  for (unsigned i = 1; i != NumOps; ++i)
> +    if (!isa<ConstantInt>(Ops[i]))
> +      return false;
> +
> +  uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
> +                                         (Value**)Ops+1, NumOps-1);
> +  Constant *C = ConstantInt::get(TD->getIntPtrType(), Offset 
> +BasePtr);
> +  return ConstantExpr::getIntToPtr(C, ResultTy);
>
>   return 0;

This last return statement is now dead.

-bw

> }
>
>
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