Index: llvm/trunk/include/llvm/Support/KnownBits.h
===================================================================
--- llvm/trunk/include/llvm/Support/KnownBits.h
+++ llvm/trunk/include/llvm/Support/KnownBits.h
@@ -24,6 +24,12 @@
   APInt Zero;
   APInt One;
 
+private:
+  // Internal constructor for creating a ConstantRange from two APInts.
+  KnownBits(APInt Zero, APInt One)
+      : Zero(std::move(Zero)), One(std::move(One)) {}
+
+public:
   // Default construct Zero and One.
   KnownBits() {}
 
@@ -54,6 +60,30 @@
     assert(!isNegative() && "Can't make a negative value non-negative");
     Zero.setSignBit();
   }
+
+  /// Truncate the underlying known Zero and One bits. This is equivalent
+  /// to truncating the value we're tracking.
+  KnownBits trunc(unsigned BitWidth) {
+    return KnownBits(Zero.trunc(BitWidth), One.trunc(BitWidth));
+  }
+
+  /// Zero extends the underlying known Zero and One bits. This is equivalent
+  /// to zero extending the value we're tracking.
+  KnownBits zext(unsigned BitWidth) {
+    return KnownBits(Zero.zext(BitWidth), One.zext(BitWidth));
+  }
+
+  /// Sign extends the underlying known Zero and One bits. This is equivalent
+  /// to sign extending the value we're tracking.
+  KnownBits sext(unsigned BitWidth) {
+    return KnownBits(Zero.sext(BitWidth), One.sext(BitWidth));
+  }
+
+  /// Zero extends or truncates the underlying known Zero and One bits. This is
+  /// equivalent to zero extending or truncating the value we're tracking.
+  KnownBits zextOrTrunc(unsigned BitWidth) {
+    return KnownBits(Zero.zextOrTrunc(BitWidth), One.zextOrTrunc(BitWidth));
+  }
 };
 
 } // end namespace llvm
Index: llvm/trunk/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp
@@ -1051,11 +1051,9 @@
     SrcBitWidth = Q.DL.getTypeSizeInBits(SrcTy->getScalarType());
 
     assert(SrcBitWidth && "SrcBitWidth can't be zero");
-    Known.Zero = Known.Zero.zextOrTrunc(SrcBitWidth);
-    Known.One = Known.One.zextOrTrunc(SrcBitWidth);
+    Known = Known.zextOrTrunc(SrcBitWidth);
     computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
-    Known.Zero = Known.Zero.zextOrTrunc(BitWidth);
-    Known.One = Known.One.zextOrTrunc(BitWidth);
+    Known = Known.zextOrTrunc(BitWidth);
     // Any top bits are known to be zero.
     if (BitWidth > SrcBitWidth)
       Known.Zero.setBitsFrom(SrcBitWidth);
@@ -1076,13 +1074,11 @@
     // Compute the bits in the result that are not present in the input.
     unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();
 
-    Known.Zero = Known.Zero.trunc(SrcBitWidth);
-    Known.One = Known.One.trunc(SrcBitWidth);
+    Known = Known.trunc(SrcBitWidth);
     computeKnownBits(I->getOperand(0), Known, Depth + 1, Q);
     // If the sign bit of the input is known set or clear, then we know the
     // top bits of the result.
-    Known.Zero = Known.Zero.sext(BitWidth);
-    Known.One = Known.One.sext(BitWidth);
+    Known = Known.sext(BitWidth);
     break;
   }
   case Instruction::Shl: {
Index: llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -402,8 +402,7 @@
 
   if (BitWidth > LOI->Known.getBitWidth()) {
     LOI->NumSignBits = 1;
-    LOI->Known.Zero = LOI->Known.Zero.zextOrTrunc(BitWidth);
-    LOI->Known.One = LOI->Known.One.zextOrTrunc(BitWidth);
+    LOI->Known = LOI->Known.zextOrTrunc(BitWidth);
   }
 
   return LOI;
Index: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2017,8 +2017,7 @@
       if (SrcOp.getValueSizeInBits() != BitWidth) {
         assert(SrcOp.getValueSizeInBits() > BitWidth &&
                "Expected BUILD_VECTOR implicit truncation");
-        Known2.One = Known2.One.trunc(BitWidth);
-        Known2.Zero = Known2.Zero.trunc(BitWidth);
+        Known2 = Known2.trunc(BitWidth);
       }
 
       // Known bits are the values that are shared by every demanded element.
@@ -2396,24 +2395,20 @@
   case ISD::ZERO_EXTEND_VECTOR_INREG: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
-    Known.Zero = Known.Zero.trunc(InBits);
-    Known.One = Known.One.trunc(InBits);
+    Known = Known.trunc(InBits);
     computeKnownBits(Op.getOperand(0), Known,
                      DemandedElts.zext(InVT.getVectorNumElements()),
                      Depth + 1);
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     Known.Zero.setBitsFrom(InBits);
     break;
   }
   case ISD::ZERO_EXTEND: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
-    Known.Zero = Known.Zero.trunc(InBits);
-    Known.One = Known.One.trunc(InBits);
+    Known = Known.trunc(InBits);
     computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     Known.Zero.setBitsFrom(InBits);
     break;
   }
@@ -2422,34 +2417,28 @@
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
 
-    Known.Zero = Known.Zero.trunc(InBits);
-    Known.One = Known.One.trunc(InBits);
+    Known = Known.trunc(InBits);
     computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
 
     // If the sign bit is known to be zero or one, then sext will extend
     // it to the top bits, else it will just zext.
-    Known.Zero = Known.Zero.sext(BitWidth);
-    Known.One = Known.One.sext(BitWidth);
+    Known = Known.sext(BitWidth);
     break;
   }
   case ISD::ANY_EXTEND: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
-    Known.Zero = Known.Zero.trunc(InBits);
-    Known.One = Known.One.trunc(InBits);
+    Known = Known.trunc(InBits);
     computeKnownBits(Op.getOperand(0), Known, Depth+1);
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     break;
   }
   case ISD::TRUNCATE: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarSizeInBits();
-    Known.Zero = Known.Zero.zext(InBits);
-    Known.One = Known.One.zext(InBits);
+    Known = Known.zext(InBits);
     computeKnownBits(Op.getOperand(0), Known, DemandedElts, Depth + 1);
-    Known.Zero = Known.Zero.trunc(BitWidth);
-    Known.One = Known.One.trunc(BitWidth);
+    Known = Known.trunc(BitWidth);
     break;
   }
   case ISD::AssertZext: {
@@ -2621,8 +2610,7 @@
     Known.One = Known.One.getHiBits(Known.One.getBitWidth() - Index * BitWidth);
 
     // Remove high part of known bit mask
-    Known.Zero = Known.Zero.trunc(BitWidth);
-    Known.One = Known.One.trunc(BitWidth);
+    Known = Known.trunc(BitWidth);
     break;
   }
   case ISD::EXTRACT_VECTOR_ELT: {
@@ -2634,10 +2622,8 @@
     const unsigned NumSrcElts = VecVT.getVectorNumElements();
     // If BitWidth > EltBitWidth the value is anyext:ed. So we do not know
     // anything about the extended bits.
-    if (BitWidth > EltBitWidth) {
-      Known.Zero = Known.Zero.trunc(EltBitWidth);
-      Known.One = Known.One.trunc(EltBitWidth);
-    }
+    if (BitWidth > EltBitWidth)
+      Known = Known.trunc(EltBitWidth);
     ConstantSDNode *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
     if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts)) {
       // If we know the element index, just demand that vector element.
@@ -2648,10 +2634,8 @@
       // Unknown element index, so ignore DemandedElts and demand them all.
       computeKnownBits(InVec, Known, Depth + 1);
     }
-    if (BitWidth > EltBitWidth) {
-      Known.Zero = Known.Zero.zext(BitWidth);
-      Known.One = Known.One.zext(BitWidth);
-    }
+    if (BitWidth > EltBitWidth)
+      Known = Known.zext(BitWidth);
     break;
   }
   case ISD::INSERT_VECTOR_ELT: {
Index: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -561,8 +561,7 @@
       if (Known2.One.getBitWidth() != BitWidth) {
         assert(Known2.getBitWidth() > BitWidth &&
                "Expected BUILD_VECTOR implicit truncation");
-        Known2.One = Known2.One.trunc(BitWidth);
-        Known2.Zero = Known2.Zero.trunc(BitWidth);
+        Known2 = Known2.trunc(BitWidth);
       }
 
       // Known bits are the values that are shared by every element.
@@ -1087,8 +1086,7 @@
     if (SimplifyDemandedBits(Op.getOperand(0), InMask, Known, TLO, Depth+1))
       return true;
     assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?");
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     Known.Zero |= NewBits;
     break;
   }
@@ -1114,8 +1112,7 @@
     if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, Known, TLO,
                              Depth+1))
       return true;
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
 
     // If the sign bit is known zero, convert this to a zero extend.
     if (Known.Zero.intersects(InSignBit))
@@ -1139,8 +1136,7 @@
     if (SimplifyDemandedBits(Op.getOperand(0), InMask, Known, TLO, Depth+1))
       return true;
     assert((Known.Zero & Known.One) == 0 && "Bits known to be one AND zero?");
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     break;
   }
   case ISD::TRUNCATE: {
@@ -1150,8 +1146,7 @@
     APInt TruncMask = NewMask.zext(OperandBitWidth);
     if (SimplifyDemandedBits(Op.getOperand(0), TruncMask, Known, TLO, Depth+1))
       return true;
-    Known.Zero = Known.Zero.trunc(BitWidth);
-    Known.One = Known.One.trunc(BitWidth);
+    Known = Known.trunc(BitWidth);
 
     // If the input is only used by this truncate, see if we can shrink it based
     // on the known demanded bits.
Index: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
@@ -26729,8 +26729,7 @@
     Known = KnownBits(InBitWidth);
     APInt DemandedSrcElts = APInt::getLowBitsSet(InNumElts, NumElts);
     DAG.computeKnownBits(N0, Known, DemandedSrcElts, Depth + 1);
-    Known.One = Known.One.zext(BitWidth);
-    Known.Zero = Known.Zero.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     Known.Zero.setBitsFrom(InBitWidth);
     break;
   }
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -329,13 +329,11 @@
   case Instruction::Trunc: {
     unsigned truncBf = I->getOperand(0)->getType()->getScalarSizeInBits();
     DemandedMask = DemandedMask.zext(truncBf);
-    Known.Zero = Known.Zero.zext(truncBf);
-    Known.One = Known.One.zext(truncBf);
+    Known = Known.zext(truncBf);
     if (SimplifyDemandedBits(I, 0, DemandedMask, Known, Depth + 1))
       return I;
     DemandedMask = DemandedMask.trunc(BitWidth);
-    Known.Zero = Known.Zero.trunc(BitWidth);
-    Known.One = Known.One.trunc(BitWidth);
+    Known = Known.trunc(BitWidth);
     assert(!(Known.Zero & Known.One) && "Bits known to be one AND zero?");
     break;
   }
@@ -365,13 +363,11 @@
     unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
 
     DemandedMask = DemandedMask.trunc(SrcBitWidth);
-    Known.Zero = Known.Zero.trunc(SrcBitWidth);
-    Known.One = Known.One.trunc(SrcBitWidth);
+    Known = Known.trunc(SrcBitWidth);
     if (SimplifyDemandedBits(I, 0, DemandedMask, Known, Depth + 1))
       return I;
     DemandedMask = DemandedMask.zext(BitWidth);
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     assert(!(Known.Zero & Known.One) && "Bits known to be one AND zero?");
     // The top bits are known to be zero.
     Known.Zero.setBitsFrom(SrcBitWidth);
@@ -391,13 +387,11 @@
       InputDemandedBits.setBit(SrcBitWidth-1);
 
     InputDemandedBits = InputDemandedBits.trunc(SrcBitWidth);
-    Known.Zero = Known.Zero.trunc(SrcBitWidth);
-    Known.One = Known.One.trunc(SrcBitWidth);
+    Known = Known.trunc(SrcBitWidth);
     if (SimplifyDemandedBits(I, 0, InputDemandedBits, Known, Depth + 1))
       return I;
     InputDemandedBits = InputDemandedBits.zext(BitWidth);
-    Known.Zero = Known.Zero.zext(BitWidth);
-    Known.One = Known.One.zext(BitWidth);
+    Known = Known.zext(BitWidth);
     assert(!(Known.Zero & Known.One) && "Bits known to be one AND zero?");
 
     // If the sign bit of the input is known set or clear, then we know the