Revert r367091, it caused PR42777.

llvm-svn: 367118

1 files changed, 2 insertions, 59 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index f5e8c4e..6bfb388 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -565,69 +565,12 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op, const APInt &DemandedBits,
 }
 
 // TODO: Can we merge SelectionDAG::GetDemandedBits into this?
-// TODO: Under what circumstances can we create nodes? Constant folding?
+// TODO: Under what circumstances can we create nodes? BITCAST? Constant?
 SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
     SDValue Op, const APInt &DemandedBits, const APInt &DemandedElts,
     SelectionDAG &DAG, unsigned Depth) const {
-  unsigned NumElts = DemandedElts.getBitWidth();
   KnownBits LHSKnown, RHSKnown;
   switch (Op.getOpcode()) {
-  case ISD::BITCAST: {
-    SDValue Src = peekThroughBitcasts(Op.getOperand(0));
-    EVT SrcVT = Op.getOperand(0).getValueType();
-    EVT DstVT = Op.getValueType();
-    unsigned NumSrcEltBits = SrcVT.getScalarSizeInBits();
-    unsigned NumDstEltBits = DstVT.getScalarSizeInBits();
-
-    if (NumSrcEltBits == NumDstEltBits)
-      if (SDValue V = SimplifyMultipleUseDemandedBits(
-              Src, DemandedBits, DemandedElts, DAG, Depth + 1))
-        return DAG.getBitcast(DstVT, V);
-
-    // TODO - bigendian once we have test coverage.
-    if (SrcVT.isVector() && (NumDstEltBits % NumSrcEltBits) == 0 &&
-        DAG.getDataLayout().isLittleEndian()) {
-      unsigned Scale = NumDstEltBits / NumSrcEltBits;
-      unsigned NumSrcElts = SrcVT.getVectorNumElements();
-      APInt DemandedSrcBits = APInt::getNullValue(NumSrcEltBits);
-      APInt DemandedSrcElts = APInt::getNullValue(NumSrcElts);
-      for (unsigned i = 0; i != Scale; ++i) {
-        unsigned Offset = i * NumSrcEltBits;
-        APInt Sub = DemandedBits.extractBits(NumSrcEltBits, Offset);
-        if (!Sub.isNullValue()) {
-          DemandedSrcBits |= Sub;
-          for (unsigned j = 0; j != NumElts; ++j)
-            if (DemandedElts[j])
-              DemandedSrcElts.setBit((j * Scale) + i);
-        }
-      }
-
-      if (SDValue V = SimplifyMultipleUseDemandedBits(
-              Src, DemandedSrcBits, DemandedSrcElts, DAG, Depth + 1))
-        return DAG.getBitcast(DstVT, V);
-    }
-
-    // TODO - bigendian once we have test coverage.
-    if ((NumSrcEltBits % NumDstEltBits) == 0 &&
-        DAG.getDataLayout().isLittleEndian()) {
-      unsigned Scale = NumSrcEltBits / NumDstEltBits;
-      unsigned NumSrcElts = SrcVT.isVector() ? SrcVT.getVectorNumElements() : 1;
-      APInt DemandedSrcBits = APInt::getNullValue(NumSrcEltBits);
-      APInt DemandedSrcElts = APInt::getNullValue(NumSrcElts);
-      for (unsigned i = 0; i != NumElts; ++i)
-        if (DemandedElts[i]) {
-          unsigned Offset = (i % Scale) * NumDstEltBits;
-          DemandedSrcBits.insertBits(DemandedBits, Offset);
-          DemandedSrcElts.setBit(i / Scale);
-        }
-
-      if (SDValue V = SimplifyMultipleUseDemandedBits(
-              Src, DemandedSrcBits, DemandedSrcElts, DAG, Depth + 1))
-        return DAG.getBitcast(DstVT, V);
-    }
-
-    break;
-  }
   case ISD::AND: {
     LHSKnown = DAG.computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
     RHSKnown = DAG.computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
@@ -679,7 +622,7 @@ SDValue TargetLowering::SimplifyMultipleUseDemandedBits(
     // If all the demanded elts are from one operand and are inline,
     // then we can use the operand directly.
     bool AllUndef = true, IdentityLHS = true, IdentityRHS = true;
-    for (unsigned i = 0; i != NumElts; ++i) {
+    for (unsigned i = 0, NumElts = ShuffleMask.size(); i != NumElts; ++i) {
       int M = ShuffleMask[i];
       if (M < 0 || !DemandedElts[i])
         continue;