[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Chris Lattner]

> +    bool HasUses = false;
> +    SmallVector<MVT::ValueType, 2> VTs;
> +    for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) {
> +      if (!N->hasNUsesOfValue(0, i)) {
> +        HasUses = true;
> +        break;
> +      }
> +      VTs.push_back(N->getValueType(i));
> +    }
> +    if (!HasUses) {
> +      SmallVector<SDOperand, 1> Ops;
> +      return CombineTo(N, DAG.getNode(ISD::UNDEF, &VTs[0], VTs.size 
> (), 0, 0),
> +                       Chain);

This can never trigger and isn't right if it did.

#1: This should trigger if the chain has uses but the other values do  
not.  If the entire node is dead, it will already have been removed.

#2. you can't create an undef with multiple results, you have to  
create multiple undefs :)

I'd suggest just writing this as:

   if (N->getValueType(1) == MVT::Other) {
     // single result case.
   } else {
     assert(N->getValueType(2) == MVT::Other);
     // multi result case.
   }

This lets you drop the looping and smallvector.

-Chris