[llvm-commits] [llvm] r118164 - /llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

[Bob Wilson]

This should be safe, but you could take it one step further and just return undef instead of creating a load from an undef pointer.

On Nov 3, 2010, at 2:36 AM, Eric Christopher wrote:

> Author: echristo
> Date: Wed Nov  3 04:36:40 2010
> New Revision: 118164
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=118164&view=rev
> Log:
> If we have an undef mask our Elt will be -1 for our access, handle
> this by using an undef as a pointer.
> 
> Fixes rdar://8625016
> 
> Modified:
>    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> 
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=118164&r1=118163&r2=118164&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed Nov  3 04:36:40 2010
> @@ -6190,7 +6190,7 @@
>   SDValue EltNo = N->getOperand(1);
> 
>   if (isa<ConstantSDNode>(EltNo)) {
> -    unsigned Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();
> +    int Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();
>     bool NewLoad = false;
>     bool BCNumEltsChanged = false;
>     EVT VT = InVec.getValueType();
> @@ -6228,7 +6228,7 @@
> 
>       // Select the input vector, guarding against out of range extract vector.
>       unsigned NumElems = VT.getVectorNumElements();
> -      int Idx = (Elt > NumElems) ? -1 : SVN->getMaskElt(Elt);
> +      int Idx = (Elt > (int)NumElems) ? -1 : SVN->getMaskElt(Elt);
>       InVec = (Idx < (int)NumElems) ? InVec.getOperand(0) : InVec.getOperand(1);
> 
>       if (InVec.getOpcode() == ISD::BIT_CONVERT)
> @@ -6257,7 +6257,11 @@
> 
>     SDValue NewPtr = LN0->getBasePtr();
>     unsigned PtrOff = 0;
> -    if (Elt) {
> +    // If Idx was -1 above, Elt is going to be -1, so just use undef as our
> +    // new pointer.
> +    if (Elt == -1) {
> +      NewPtr = DAG.getUNDEF(NewPtr.getValueType());
> +    } else if (Elt) {
>       PtrOff = LVT.getSizeInBits() * Elt / 8;
>       EVT PtrType = NewPtr.getValueType();
>       if (TLI.isBigEndian())
> 
> 
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