PR5207: Change APInt methods trunc(), sext(), zext(), sextOrTrunc() and

zextOrTrunc(), and APSInt methods extend(), extOrTrunc() and new method
trunc(), to be const and to return a new value instead of modifying the
object in place.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121120 91177308-0d34-0410-b5e6-96231b3b80d8

22 files changed, 192 insertions, 224 deletions

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 74bee947a3..3ab18fd3c0 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -206,14 +206,14 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
     Value *CastOp = cast<CastInst>(V)->getOperand(0);
     unsigned OldWidth = Scale.getBitWidth();
     unsigned SmallWidth = CastOp->getType()->getPrimitiveSizeInBits();
-    Scale.trunc(SmallWidth);
-    Offset.trunc(SmallWidth);
+    Scale = Scale.trunc(SmallWidth);
+    Offset = Offset.trunc(SmallWidth);
     Extension = isa<SExtInst>(V) ? EK_SignExt : EK_ZeroExt;
 
     Value *Result = GetLinearExpression(CastOp, Scale, Offset, Extension,
                                         TD, Depth+1);
-    Scale.zext(OldWidth);
-    Offset.zext(OldWidth);
+    Scale = Scale.zext(OldWidth);
+    Offset = Offset.zext(OldWidth);
     
     return Result;
   }
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 70ee9ddfa6..68a55b6b94 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -610,10 +610,8 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
   APInt BasePtr(BitWidth, 0);
   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
     if (CE->getOpcode() == Instruction::IntToPtr)
-      if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0))) {
-        BasePtr = Base->getValue();
-        BasePtr.zextOrTrunc(BitWidth);
-      }
+      if (ConstantInt *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))
+        BasePtr = Base->getValue().zextOrTrunc(BitWidth);
   if (Ptr->isNullValue() || BasePtr != 0) {
     Constant *C = ConstantInt::get(Ptr->getContext(), Offset+BasePtr);
     return ConstantExpr::getIntToPtr(C, ResultTy);
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 7e50d3d38e..b0c1c75cb6 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -3367,8 +3367,8 @@ const SCEV *ScalarEvolution::createSCEV(Value *V) {
               // If C is a single bit, it may be in the sign-bit position
               // before the zero-extend. In this case, represent the xor
               // using an add, which is equivalent, and re-apply the zext.
-              APInt Trunc = APInt(CI->getValue()).trunc(Z0TySize);
-              if (APInt(Trunc).zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
+              APInt Trunc = CI->getValue().trunc(Z0TySize);
+              if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
                   Trunc.isSignBit())
                 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
                                          UTy);
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 7ab4d2ba04..a612f130d1 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -255,14 +255,13 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
     else
       SrcBitWidth = SrcTy->getScalarSizeInBits();
     
-    APInt MaskIn(Mask);
-    MaskIn.zextOrTrunc(SrcBitWidth);
-    KnownZero.zextOrTrunc(SrcBitWidth);
-    KnownOne.zextOrTrunc(SrcBitWidth);
+    APInt MaskIn = Mask.zextOrTrunc(SrcBitWidth);
+    KnownZero = KnownZero.zextOrTrunc(SrcBitWidth);
+    KnownOne = KnownOne.zextOrTrunc(SrcBitWidth);
     ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD,
                       Depth+1);
-    KnownZero.zextOrTrunc(BitWidth);
-    KnownOne.zextOrTrunc(BitWidth);
+    KnownZero = KnownZero.zextOrTrunc(BitWidth);
+    KnownOne = KnownOne.zextOrTrunc(BitWidth);
     // Any top bits are known to be zero.
     if (BitWidth > SrcBitWidth)
       KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
@@ -284,15 +283,14 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
     // Compute the bits in the result that are not present in the input.
     unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();
       
-    APInt MaskIn(Mask); 
-    MaskIn.trunc(SrcBitWidth);
-    KnownZero.trunc(SrcBitWidth);
-    KnownOne.trunc(SrcBitWidth);
+    APInt MaskIn = Mask.trunc(SrcBitWidth);
+    KnownZero = KnownZero.trunc(SrcBitWidth);
+    KnownOne = KnownOne.trunc(SrcBitWidth);
     ComputeMaskedBits(I->getOperand(0), MaskIn, KnownZero, KnownOne, TD,
                       Depth+1);
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
 
     // If the sign bit of the input is known set or clear, then we know the
     // top bits of the result.
diff --git a/lib/AsmParser/LLLexer.cpp b/lib/AsmParser/LLLexer.cpp
index f924b5a908..3c74c26f55 100644
--- a/lib/AsmParser/LLLexer.cpp
+++ b/lib/AsmParser/LLLexer.cpp
@@ -682,7 +682,7 @@ lltok::Kind LLLexer::LexIdentifier() {
     APInt Tmp(bits, StringRef(TokStart+3, len), 16);
     uint32_t activeBits = Tmp.getActiveBits();
     if (activeBits > 0 && activeBits < bits)
-      Tmp.trunc(activeBits);
+      Tmp = Tmp.trunc(activeBits);
     APSIntVal = APSInt(Tmp, TokStart[0] == 'u');
     return lltok::APSInt;
   }
@@ -809,12 +809,12 @@ lltok::Kind LLLexer::LexDigitOrNegative() {
     if (TokStart[0] == '-') {
       uint32_t minBits = Tmp.getMinSignedBits();
       if (minBits > 0 && minBits < numBits)
-        Tmp.trunc(minBits);
+        Tmp = Tmp.trunc(minBits);
       APSIntVal = APSInt(Tmp, false);
     } else {
       uint32_t activeBits = Tmp.getActiveBits();
       if (activeBits > 0 && activeBits < numBits)
-        Tmp.trunc(activeBits);
+        Tmp = Tmp.trunc(activeBits);
       APSIntVal = APSInt(Tmp, true);
     }
     return lltok::APSInt;
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index a1f70fb024..68f79465be 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -2575,7 +2575,7 @@ bool LLParser::ConvertValIDToValue(const Type *Ty, ValID &ID, Value *&V,
   case ValID::t_APSInt:
     if (!Ty->isIntegerTy())
       return Error(ID.Loc, "integer constant must have integer type");
-    ID.APSIntVal.extOrTrunc(Ty->getPrimitiveSizeInBits());
+    ID.APSIntVal = ID.APSIntVal.extOrTrunc(Ty->getPrimitiveSizeInBits());
     V = ConstantInt::get(Context, ID.APSIntVal);
     return false;
   case ValID::t_APFloat:
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 994dbd497c..279452a219 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2133,7 +2133,7 @@ SDValue DAGCombiner::visitAND(SDNode *N) {
   if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) {
     SDValue N0Op0 = N0.getOperand(0);
     APInt Mask = ~N1C->getAPIntValue();
-    Mask.trunc(N0Op0.getValueSizeInBits());
+    Mask = Mask.trunc(N0Op0.getValueSizeInBits());
     if (DAG.MaskedValueIsZero(N0Op0, Mask)) {
       SDValue Zext = DAG.getNode(ISD::ZERO_EXTEND, N->getDebugLoc(),
                                  N0.getValueType(), N0Op0);
@@ -2866,7 +2866,7 @@ SDValue DAGCombiner::visitSHL(SDNode *N) {
       EVT TruncVT = N1.getValueType();
       SDValue N100 = N1.getOperand(0).getOperand(0);
       APInt TruncC = N101C->getAPIntValue();
-      TruncC.trunc(TruncVT.getSizeInBits());
+      TruncC = TruncC.trunc(TruncVT.getSizeInBits());
       return DAG.getNode(ISD::SHL, N->getDebugLoc(), VT, N0,
                          DAG.getNode(ISD::AND, N->getDebugLoc(), TruncVT,
                                      DAG.getNode(ISD::TRUNCATE,
@@ -3022,7 +3022,7 @@ SDValue DAGCombiner::visitSRA(SDNode *N) {
       EVT TruncVT = N1.getValueType();
       SDValue N100 = N1.getOperand(0).getOperand(0);
       APInt TruncC = N101C->getAPIntValue();
-      TruncC.trunc(TruncVT.getScalarType().getSizeInBits());
+      TruncC = TruncC.trunc(TruncVT.getScalarType().getSizeInBits());
       return DAG.getNode(ISD::SRA, N->getDebugLoc(), VT, N0,
                          DAG.getNode(ISD::AND, N->getDebugLoc(),
                                      TruncVT,
@@ -3163,7 +3163,7 @@ SDValue DAGCombiner::visitSRL(SDNode *N) {
       EVT TruncVT = N1.getValueType();
       SDValue N100 = N1.getOperand(0).getOperand(0);
       APInt TruncC = N101C->getAPIntValue();
-      TruncC.trunc(TruncVT.getSizeInBits());
+      TruncC = TruncC.trunc(TruncVT.getSizeInBits());
       return DAG.getNode(ISD::SRL, N->getDebugLoc(), VT, N0,
                          DAG.getNode(ISD::AND, N->getDebugLoc(),
                                      TruncVT,
@@ -3706,7 +3706,7 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
       X = DAG.getNode(ISD::TRUNCATE, X.getDebugLoc(), VT, X);
     }
     APInt Mask = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
-    Mask.zext(VT.getSizeInBits());
+    Mask = Mask.zext(VT.getSizeInBits());
     return DAG.getNode(ISD::AND, N->getDebugLoc(), VT,
                        X, DAG.getConstant(Mask, VT));
   }
@@ -3907,7 +3907,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
       X = DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, X);
     }
     APInt Mask = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
-    Mask.zext(VT.getSizeInBits());
+    Mask = Mask.zext(VT.getSizeInBits());
     return DAG.getNode(ISD::AND, N->getDebugLoc(), VT,
                        X, DAG.getConstant(Mask, VT));
   }
@@ -4614,7 +4614,7 @@ ConstantFoldBITCASTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {
         if (Op.getOpcode() == ISD::UNDEF) continue;
         EltIsUndef = false;
 
-        NewBits |= APInt(cast<ConstantSDNode>(Op)->getAPIntValue()).
+        NewBits |= cast<ConstantSDNode>(Op)->getAPIntValue().
                    zextOrTrunc(SrcBitSize).zext(DstBitSize);
       }
 
@@ -4644,13 +4644,13 @@ ConstantFoldBITCASTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {
       continue;
     }
 
-    APInt OpVal = APInt(cast<ConstantSDNode>(BV->getOperand(i))->
-                        getAPIntValue()).zextOrTrunc(SrcBitSize);
+    APInt OpVal = cast<ConstantSDNode>(BV->getOperand(i))->
+                  getAPIntValue().zextOrTrunc(SrcBitSize);
 
     for (unsigned j = 0; j != NumOutputsPerInput; ++j) {
-      APInt ThisVal = APInt(OpVal).trunc(DstBitSize);
+      APInt ThisVal = OpVal.trunc(DstBitSize);
       Ops.push_back(DAG.getConstant(ThisVal, DstEltVT));
-      if (isS2V && i == 0 && j == 0 && APInt(ThisVal).zext(SrcBitSize) == OpVal)
+      if (isS2V && i == 0 && j == 0 && ThisVal.zext(SrcBitSize) == OpVal)
         // Simply turn this into a SCALAR_TO_VECTOR of the new type.
         return DAG.getNode(ISD::SCALAR_TO_VECTOR, BV->getDebugLoc(), VT,
                            Ops[0]);
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 2f7fd25f24..aff087f61e 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -749,7 +749,7 @@ SDValue SelectionDAGLegalize::OptimizeFloatStore(StoreSDNode* ST) {
         // stores.  If the target supports neither 32- nor 64-bits, this
         // xform is certainly not worth it.
         const APInt &IntVal =CFP->getValueAPF().bitcastToAPInt();
-        SDValue Lo = DAG.getConstant(APInt(IntVal).trunc(32), MVT::i32);
+        SDValue Lo = DAG.getConstant(IntVal.trunc(32), MVT::i32);
         SDValue Hi = DAG.getConstant(IntVal.lshr(32).trunc(32), MVT::i32);
         if (TLI.isBigEndian()) std::swap(Lo, Hi);
 
diff --git a/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 271352bc62..cb9c2fb9b4 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -1435,7 +1435,7 @@ void DAGTypeLegalizer::ExpandIntRes_Constant(SDNode *N,
   EVT NVT = TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0));
   unsigned NBitWidth = NVT.getSizeInBits();
   const APInt &Cst = cast<ConstantSDNode>(N)->getAPIntValue();
-  Lo = DAG.getConstant(APInt(Cst).trunc(NBitWidth), NVT);
+  Lo = DAG.getConstant(Cst.trunc(NBitWidth), NVT);
   Hi = DAG.getConstant(Cst.lshr(NBitWidth).trunc(NBitWidth), NVT);
 }
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 7e408a0707..2e8b6546ec 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1806,7 +1806,7 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
 
     // If the sign extended bits are demanded, we know that the sign
     // bit is demanded.
-    InSignBit.zext(BitWidth);
+    InSignBit = InSignBit.zext(BitWidth);
     if (NewBits.getBoolValue())
       InputDemandedBits |= InSignBit;
 
@@ -1849,13 +1849,12 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarType().getSizeInBits();
     APInt NewBits   = APInt::getHighBitsSet(BitWidth, BitWidth - InBits) & Mask;
-    APInt InMask    = Mask;
-    InMask.trunc(InBits);
-    KnownZero.trunc(InBits);
-    KnownOne.trunc(InBits);
+    APInt InMask    = Mask.trunc(InBits);
+    KnownZero = KnownZero.trunc(InBits);
+    KnownOne = KnownOne.trunc(InBits);
     ComputeMaskedBits(Op.getOperand(0), InMask, KnownZero, KnownOne, Depth+1);
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     KnownZero |= NewBits;
     return;
   }
@@ -1864,16 +1863,15 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
     unsigned InBits = InVT.getScalarType().getSizeInBits();
     APInt InSignBit = APInt::getSignBit(InBits);
     APInt NewBits   = APInt::getHighBitsSet(BitWidth, BitWidth - InBits) & Mask;
-    APInt InMask = Mask;
-    InMask.trunc(InBits);
+    APInt InMask = Mask.trunc(InBits);
 
     // If any of the sign extended bits are demanded, we know that the sign
     // bit is demanded. Temporarily set this bit in the mask for our callee.
     if (NewBits.getBoolValue())
       InMask |= InSignBit;
 
-    KnownZero.trunc(InBits);
-    KnownOne.trunc(InBits);
+    KnownZero = KnownZero.trunc(InBits);
+    KnownOne = KnownOne.trunc(InBits);
     ComputeMaskedBits(Op.getOperand(0), InMask, KnownZero, KnownOne, Depth+1);
 
     // Note if the sign bit is known to be zero or one.
@@ -1885,13 +1883,12 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
     // If the sign bit wasn't actually demanded by our caller, we don't
     // want it set in the KnownZero and KnownOne result values. Reset the
     // mask and reapply it to the result values.
-    InMask = Mask;
-    InMask.trunc(InBits);
+    InMask = Mask.trunc(InBits);
     KnownZero &= InMask;
     KnownOne  &= InMask;
 
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
 
     // If the sign bit is known zero or one, the top bits match.
     if (SignBitKnownZero)
@@ -1903,26 +1900,24 @@ void SelectionDAG::ComputeMaskedBits(SDValue Op, const APInt &Mask,
   case ISD::ANY_EXTEND: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarType().getSizeInBits();
-    APInt InMask = Mask;
-    InMask.trunc(InBits);
-    KnownZero.trunc(InBits);
-    KnownOne.trunc(InBits);
+    APInt InMask = Mask.trunc(InBits);
+    KnownZero = KnownZero.trunc(InBits);
+    KnownOne = KnownOne.trunc(InBits);
     ComputeMaskedBits(Op.getOperand(0), InMask, KnownZero, KnownOne, Depth+1);
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     return;
   }
   case ISD::TRUNCATE: {
     EVT InVT = Op.getOperand(0).getValueType();
     unsigned InBits = InVT.getScalarType().getSizeInBits();
-    APInt InMask = Mask;
-    InMask.zext(InBits);
-    KnownZero.zext(InBits);
-    KnownOne.zext(InBits);
+    APInt InMask = Mask.zext(InBits);
+    KnownZero = KnownZero.zext(InBits);
+    KnownOne = KnownOne.zext(InBits);
     ComputeMaskedBits(Op.getOperand(0), InMask, KnownZero, KnownOne, Depth+1);
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
-    KnownZero.trunc(BitWidth);
-    KnownOne.trunc(BitWidth);
+    KnownZero = KnownZero.trunc(BitWidth);
+    KnownOne = KnownOne.trunc(BitWidth);
     break;
   }
   case ISD::AssertZext: {
@@ -2349,11 +2344,11 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL,
     switch (Opcode) {
     default: break;
     case ISD::SIGN_EXTEND:
-      return getConstant(APInt(Val).sextOrTrunc(VT.getSizeInBits()), VT);
+      return getConstant(Val.sextOrTrunc(VT.getSizeInBits()), VT);
     case ISD::ANY_EXTEND:
     case ISD::ZERO_EXTEND:
     case ISD::TRUNCATE:
-      return getConstant(APInt(Val).zextOrTrunc(VT.getSizeInBits()), VT);
+      return getConstant(Val.zextOrTrunc(VT.getSizeInBits()), VT);
     case ISD::UINT_TO_FP:
     case ISD::SINT_TO_FP: {
       // No compile time operations on ppcf128.
@@ -6418,7 +6413,7 @@ bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue,
     if (OpVal.getOpcode() == ISD::UNDEF)
       SplatUndef |= APInt::getBitsSet(sz, BitPos, BitPos + EltBitSize);
     else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(OpVal))
-      SplatValue |= APInt(CN->getAPIntValue()).zextOrTrunc(EltBitSize).
+      SplatValue |= CN->getAPIntValue().zextOrTrunc(EltBitSize).
                     zextOrTrunc(sz) << BitPos;
     else if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(OpVal))
       SplatValue |= CN->getValueAPF().bitcastToAPInt().zextOrTrunc(sz) <<BitPos;
@@ -6433,10 +6428,10 @@ bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue,
   while (sz > 8) {
 
     unsigned HalfSize = sz / 2;
-    APInt HighValue = APInt(SplatValue).lshr(HalfSize).trunc(HalfSize);
-    APInt LowValue = APInt(SplatValue).trunc(HalfSize);
-    APInt HighUndef = APInt(SplatUndef).lshr(HalfSize).trunc(HalfSize);
-    APInt LowUndef = APInt(SplatUndef).trunc(HalfSize);
+    APInt HighValue = SplatValue.lshr(HalfSize).trunc(HalfSize);
+    APInt LowValue = SplatValue.trunc(HalfSize);
+    APInt HighUndef = SplatUndef.lshr(HalfSize).trunc(HalfSize);
+    APInt LowUndef = SplatUndef.trunc(HalfSize);
 
     // If the two halves do not match (ignoring undef bits), stop here.
     if ((HighValue & ~LowUndef) != (LowValue & ~HighUndef) ||
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 64debfc3b6..7962c3e1b5 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1866,9 +1866,8 @@ static inline bool areJTsAllowed(const TargetLowering &TLI) {
 }
 
 static APInt ComputeRange(const APInt &First, const APInt &Last) {
-  APInt LastExt(Last), FirstExt(First);
   uint32_t BitWidth = std::max(Last.getBitWidth(), First.getBitWidth()) + 1;
-  LastExt.sext(BitWidth); FirstExt.sext(BitWidth);
+  APInt LastExt = Last.sext(BitWidth), FirstExt = First.sext(BitWidth);
   return (LastExt - FirstExt + 1ULL);
 }
 
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index b2c2dbb927..d91c13cd6b 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1520,8 +1520,8 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
     if ((NewBits & NewMask) == 0)
       return TLO.CombineTo(Op, Op.getOperand(0));
 
-    APInt InSignBit = APInt::getSignBit(EVT.getScalarType().getSizeInBits());
-    InSignBit.zext(BitWidth);
+    APInt InSignBit =
+      APInt::getSignBit(EVT.getScalarType().getSizeInBits()).zext(BitWidth);
     APInt InputDemandedBits =
       APInt::getLowBitsSet(BitWidth,
                            EVT.getScalarType().getSizeInBits()) &
@@ -1556,8 +1556,7 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
   case ISD::ZERO_EXTEND: {
     unsigned OperandBitWidth =
       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
-    APInt InMask = NewMask;
-    InMask.trunc(OperandBitWidth);
+    APInt InMask = NewMask.trunc(OperandBitWidth);
 
     // If none of the top bits are demanded, convert this into an any_extend.
     APInt NewBits =
@@ -1571,8 +1570,8 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
                              KnownZero, KnownOne, TLO, Depth+1))
       return true;
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     KnownZero |= NewBits;
     break;
   }
@@ -1593,13 +1592,13 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
     // bit is demanded.
     APInt InDemandedBits = InMask & NewMask;
     InDemandedBits |= InSignBit;
-    InDemandedBits.trunc(InBits);
+    InDemandedBits = InDemandedBits.trunc(InBits);
 
     if (SimplifyDemandedBits(Op.getOperand(0), InDemandedBits, KnownZero,
                              KnownOne, TLO, Depth+1))
       return true;
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
 
     // If the sign bit is known zero, convert this to a zero extend.
     if (KnownZero.intersects(InSignBit))
@@ -1620,14 +1619,13 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
   case ISD::ANY_EXTEND: {
     unsigned OperandBitWidth =
       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
-    APInt InMask = NewMask;
-    InMask.trunc(OperandBitWidth);
+    APInt InMask = NewMask.trunc(OperandBitWidth);
     if (SimplifyDemandedBits(Op.getOperand(0), InMask,
                              KnownZero, KnownOne, TLO, Depth+1))
       return true;
     assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     break;
   }
   case ISD::TRUNCATE: {
@@ -1635,13 +1633,12 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
     // zero/one bits live out.
     unsigned OperandBitWidth =
       Op.getOperand(0).getValueType().getScalarType().getSizeInBits();
-    APInt TruncMask = NewMask;
-    TruncMask.zext(OperandBitWidth);
+    APInt TruncMask = NewMask.zext(OperandBitWidth);
     if (SimplifyDemandedBits(Op.getOperand(0), TruncMask,
                              KnownZero, KnownOne, TLO, Depth+1))
       return true;
-    KnownZero.trunc(BitWidth);
-    KnownOne.trunc(BitWidth);
+    KnownZero = KnownZero.trunc(BitWidth);
+    KnownOne = KnownOne.trunc(BitWidth);
 
     // If the input is only used by this truncate, see if we can shrink it based
     // on the known demanded bits.
@@ -1662,8 +1659,7 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op,
           break;
         APInt HighBits = APInt::getHighBitsSet(OperandBitWidth,
                                                OperandBitWidth - BitWidth);
-        HighBits = HighBits.lshr(ShAmt->getZExtValue());
-        HighBits.trunc(BitWidth);
+        HighBits = HighBits.lshr(ShAmt->getZExtValue()).trunc(BitWidth);
 
         if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) {
           // None of the shifted in bits are needed.  Add a truncate of the
@@ -1969,7 +1965,7 @@ TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
             (isOperationLegal(ISD::SETCC, newVT) &&
               getCondCodeAction(Cond, newVT)==Legal))
           return DAG.getSetCC(dl, VT, N0.getOperand(0),
-                              DAG.getConstant(APInt(C1).trunc(InSize), newVT),
+                              DAG.getConstant(C1.trunc(InSize), newVT),
                               Cond);
         break;
       }
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index c0151e26fb..a83801ed06 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -3310,7 +3310,7 @@ namespace {
     // Truncate the significand down to its active bit count, but
     // don't try to drop below 32.
     unsigned newPrecision = std::max(32U, significand.getActiveBits());
-    significand.trunc(newPrecision);
+    significand = significand.trunc(newPrecision);
   }
 
 
@@ -3415,7 +3415,7 @@ void APFloat::toString(SmallVectorImpl<char> &Str,
     // Nothing to do.
   } else if (exp > 0) {
     // Just shift left.
-    significand.zext(semantics->precision + exp);
+    significand = significand.zext(semantics->precision + exp);
     significand <<= exp;
     exp = 0;
   } else { /* exp < 0 */
@@ -3434,7 +3434,7 @@ void APFloat::toString(SmallVectorImpl<char> &Str,
 
     // Multiply significand by 5^e.
     //   N * 5^0101 == N * 5^(1*1) * 5^(0*2) * 5^(1*4) * 5^(0*8)
-    significand.zext(precision);
+    significand = significand.zext(precision);
     APInt five_to_the_i(precision, 5);
     while (true) {
       if (texp & 1) significand *= five_to_the_i;
diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index e7ff15cadb..77033428b5 100644
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -995,96 +995,90 @@ double APInt::roundToDouble(bool isSigned) const {
 }
 
 // Truncate to new width.
-APInt &APInt::trunc(unsigned width) {
+APInt APInt::trunc(unsigned width) const {
   assert(width < BitWidth && "Invalid APInt Truncate request");
   assert(width && "Can't truncate to 0 bits");
-  unsigned wordsBefore = getNumWords();
-  BitWidth = width;
-  unsigned wordsAfter = getNumWords();
-  if (wordsBefore != wordsAfter) {
-    if (wordsAfter == 1) {
-      uint64_t *tmp = pVal;
-      VAL = pVal[0];
-      delete [] tmp;
-    } else {
-      uint64_t *newVal = getClearedMemory(wordsAfter);
-      for (unsigned i = 0; i < wordsAfter; ++i)
-        newVal[i] = pVal[i];
-      delete [] pVal;
-      pVal = newVal;
-    }
-  }
-  return clearUnusedBits();
+
+  if (width <= APINT_BITS_PER_WORD)
+    return APInt(width, getRawData()[0]);
+
+  APInt Result(getMemory(getNumWords(width)), width);
+
+  // Copy full words.
+  unsigned i;
+  for (i = 0; i != width / APINT_BITS_PER_WORD; i++)
+    Result.pVal[i] = pVal[i];
+
+  // Truncate and copy any partial word.
+  unsigned bits = (0 - width) % APINT_BITS_PER_WORD;
+  if (bits != 0)
+    Result.pVal[i] = pVal[i] << bits >> bits;
+
+  return Result;
 }
 
 // Sign extend to a new width.
-APInt &APInt::sext(unsigned width) {
+APInt APInt::sext(unsigned width) const {
   assert(width > BitWidth && "Invalid APInt SignExtend request");
-  // If the sign bit isn't set, this is the same as zext.
-  if (!isNegative()) {
-    zext(width);
-    return *this;
+
+  if (width <= APINT_BITS_PER_WORD) {
+    uint64_t val = VAL << (APINT_BITS_PER_WORD - BitWidth);
+    val = (int64_t)val >> (width - BitWidth);
+    return APInt(width, val >> (APINT_BITS_PER_WORD - width));
   }
 
-  // The sign bit is set. First, get some facts
-  unsigned wordsBefore = getNumWords();
-  unsigned wordBits = BitWidth % APINT_BITS_PER_WORD;
-  BitWidth = width;
-  unsigned wordsAfter = getNumWords();
-
-  // Mask the high order word appropriately
-  if (wordsBefore == wordsAfter) {
-    unsigned newWordBits = width % APINT_BITS_PER_WORD;
-    // The extension is contained to the wordsBefore-1th word.
-    uint64_t mask = ~0ULL;
-    if (newWordBits)
-      mask >>= APINT_BITS_PER_WORD - newWordBits;
-    mask <<= wordBits;
-    if (wordsBefore == 1)
-      VAL |= mask;
-    else
-      pVal[wordsBefore-1] |= mask;
-    return clearUnusedBits();
+  APInt Result(getMemory(getNumWords(width)), width);
+
+  // Copy full words.
+  unsigned i;
+  uint64_t word = 0;
+  for (i = 0; i != BitWidth / APINT_BITS_PER_WORD; i++) {
+    word = getRawData()[i];
+    Result.pVal[i] = word;
   }
 
-  uint64_t mask = wordBits == 0 ? 0 : ~0ULL << wordBits;
-  uint64_t *newVal = getMemory(wordsAfter);
-  if (wordsBefore == 1)
-    newVal[0] = VAL | mask;
-  else {
-    for (unsigned i = 0; i < wordsBefore; ++i)
-      newVal[i] = pVal[i];
-    newVal[wordsBefore-1] |= mask;
+  // Read and sign-extend any partial word.
+  unsigned bits = (0 - BitWidth) % APINT_BITS_PER_WORD;
+  if (bits != 0)
+    word = (int64_t)getRawData()[i] << bits >> bits;
+  else
+    word = (int64_t)word >> (APINT_BITS_PER_WORD - 1);
+
+  // Write remaining full words.
+  for (; i != width / APINT_BITS_PER_WORD; i++) {
+    Result.pVal[i] = word;
+    word = (int64_t)word >> (APINT_BITS_PER_WORD - 1);
   }
-  for (unsigned i = wordsBefore; i < wordsAfter; i++)
-    newVal[i] = -1ULL;
-  if (wordsBefore != 1)
-    delete [] pVal;
-  pVal = newVal;
-  return clearUnusedBits();
+
+  // Write any partial word.
+  bits = (0 - width) % APINT_BITS_PER_WORD;
+  if (bits != 0)
+    Result.pVal[i] = word << bits >> bits;
+
+  return Result;
 }
 
 //  Zero extend to a new width.
-APInt &APInt::zext(unsigned width) {
+APInt APInt::zext(unsigned width) const {
   assert(width > BitWidth && "Invalid APInt ZeroExtend request");
-  unsigned wordsBefore = getNumWords();
-  BitWidth = width;
-  unsigned wordsAfter = getNumWords();
-  if (wordsBefore != wordsAfter) {
-    uint64_t *newVal = getClearedMemory(wordsAfter);
-    if (wordsBefore == 1)
-      newVal[0] = VAL;
-    else
-      for (unsigned i = 0; i < wordsBefore; ++i)
-        newVal[i] = pVal[i];
-    if (wordsBefore != 1)
-      delete [] pVal;
-    pVal = newVal;
-  }
-  return *this;
+
+  if (width <= APINT_BITS_PER_WORD)
+    return APInt(width, VAL);
+
+  APInt Result(getMemory(getNumWords(width)), width);
+
+  // Copy words.
+  unsigned i;
+  for (i = 0; i != getNumWords(); i++)
+    Result.pVal[i] = getRawData()[i];
+
+  // Zero remaining words.
+  memset(&Result.pVal[i], 0, (Result.getNumWords() - i) * APINT_WORD_SIZE);
+
+  return Result;
 }
 
-APInt &APInt::zextOrTrunc(unsigned width) {
+APInt APInt::zextOrTrunc(unsigned width) const {
   if (BitWidth < width)
     return zext(width);
   if (BitWidth > width)
@@ -1092,7 +1086,7 @@ APInt &APInt::zextOrTrunc(unsigned width) {
   return *this;
 }
 
-APInt &APInt::sextOrTrunc(unsigned width) {
+APInt APInt::sextOrTrunc(unsigned width) const {
   if (BitWidth < width)
     return sext(width);
   if (BitWidth > width)
diff --git a/lib/Support/ConstantRange.cpp b/lib/Support/ConstantRange.cpp
index 7f68fd32ae..493f7083db 100644
--- a/lib/Support/ConstantRange.cpp
+++ b/lib/Support/ConstantRange.cpp
@@ -442,9 +442,7 @@ ConstantRange ConstantRange::zeroExtend(uint32_t DstTySize) const {
     // Change into [0, 1 << src bit width)
     return ConstantRange(APInt(DstTySize,0), APInt(DstTySize,1).shl(SrcTySize));
 
-  APInt L = Lower; L.zext(DstTySize);
-  APInt U = Upper; U.zext(DstTySize);
-  return ConstantRange(L, U);
+  return ConstantRange(Lower.zext(DstTySize), Upper.zext(DstTySize));
 }
 
 /// signExtend - Return a new range in the specified integer type, which must
@@ -461,9 +459,7 @@ ConstantRange ConstantRange::signExtend(uint32_t DstTySize) const {
                          APInt::getLowBitsSet(DstTySize, SrcTySize-1) + 1);
   }
 
-  APInt L = Lower; L.sext(DstTySize);
-  APInt U = Upper; U.sext(DstTySize);
-  return ConstantRange(L, U);
+  return ConstantRange(Lower.sext(DstTySize), Upper.sext(DstTySize));
 }
 
 /// truncate - Return a new range in the specified integer type, which must be
@@ -477,9 +473,7 @@ ConstantRange ConstantRange::truncate(uint32_t DstTySize) const {
   if (isFullSet() || getSetSize().ugt(Size))
     return ConstantRange(DstTySize, /*isFullSet=*/true);
 
-  APInt L = Lower; L.trunc(DstTySize);
-  APInt U = Upper; U.trunc(DstTySize);
-  return ConstantRange(L, U);
+  return ConstantRange(Lower.trunc(DstTySize), Upper.trunc(DstTySize));
 }
 
 /// zextOrTrunc - make this range have the bit width given by \p DstTySize. The
diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 8e636c3317..5398051964 100644
--- a/lib/Support/StringRef.cpp
+++ b/lib/Support/StringRef.cpp
@@ -371,7 +371,7 @@ bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
   if (BitWidth < Result.getBitWidth())
     BitWidth = Result.getBitWidth(); // don't shrink the result
   else
-    Result.zext(BitWidth);
+    Result = Result.zext(BitWidth);
 
   APInt RadixAP, CharAP; // unused unless !IsPowerOf2Radix
   if (!IsPowerOf2Radix) {
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index c162757cbd..22efa48709 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -4006,7 +4006,7 @@ static SDValue SkipExtension(SDNode *N, SelectionDAG &DAG) {
   for (unsigned i = 0; i != NumElts; ++i) {
     ConstantSDNode *C = cast<ConstantSDNode>(N->getOperand(i));
     const APInt &CInt = C->getAPIntValue();
-    Ops.push_back(DAG.getConstant(APInt(CInt).trunc(EltSize), TruncVT));
+    Ops.push_back(DAG.getConstant(CInt.trunc(EltSize), TruncVT));
   }
   return DAG.getNode(ISD::BUILD_VECTOR, N->getDebugLoc(),
                      MVT::getVectorVT(TruncVT, NumElts), Ops.data(), NumElts);
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 6efff32416..d2841af8bc 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -939,8 +939,7 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
       // If all the high bits are known, we can do this xform.
       if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
         // Pull in the high bits from known-ones set.
-        APInt NewRHS(RHS->getValue());
-        NewRHS.zext(SrcBits);
+        APInt NewRHS = RHS->getValue().zext(SrcBits);
         NewRHS |= KnownOne;
         return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
                             ConstantInt::get(ICI.getContext(), NewRHS));
@@ -1022,10 +1021,8 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
              (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
           uint32_t BitWidth = 
             cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
-          APInt NewCST = AndCST->getValue();
-          NewCST.zext(BitWidth);
-          APInt NewCI = RHSV;
-          NewCI.zext(BitWidth);
+          APInt NewCST = AndCST->getValue().zext(BitWidth);
+          APInt NewCI = RHSV.zext(BitWidth);
           Value *NewAnd = 
             Builder->CreateAnd(Cast->getOperand(0),
                            ConstantInt::get(ICI.getContext(), NewCST),
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 1433f7bbc9..6bce6a2ed1 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -29,11 +29,11 @@ static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
   uint32_t W = C1->getBitWidth();
   APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
   if (sign) {
-    LHSExt.sext(W * 2);
-    RHSExt.sext(W * 2);
+    LHSExt = LHSExt.sext(W * 2);
+    RHSExt = RHSExt.sext(W * 2);
   } else {
-    LHSExt.zext(W * 2);
-    RHSExt.zext(W * 2);
+    LHSExt = LHSExt.zext(W * 2);
+    RHSExt = RHSExt.zext(W * 2);
   }
   
   APInt MulExt = LHSExt * RHSExt;
diff --git a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 5366bdd0c3..48184c0bd2 100644
--- a/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -34,7 +34,7 @@ static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
   if (!OpC) return false;
 
   // If there are no bits set that aren't demanded, nothing to do.
-  Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
+  Demanded = Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
   if ((~Demanded & OpC->getValue()) == 0)
     return false;
 
@@ -388,15 +388,15 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     break;
   case Instruction::Trunc: {
     unsigned truncBf = I->getOperand(0)->getType()->getScalarSizeInBits();
-    DemandedMask.zext(truncBf);
-    KnownZero.zext(truncBf);
-    KnownOne.zext(truncBf);
+    DemandedMask = DemandedMask.zext(truncBf);
+    KnownZero = KnownZero.zext(truncBf);
+    KnownOne = KnownOne.zext(truncBf);
     if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask, 
                              KnownZero, KnownOne, Depth+1))
       return I;
-    DemandedMask.trunc(BitWidth);
-    KnownZero.trunc(BitWidth);
-    KnownOne.trunc(BitWidth);
+    DemandedMask = DemandedMask.trunc(BitWidth);
+    KnownZero = KnownZero.trunc(BitWidth);
+    KnownOne = KnownOne.trunc(BitWidth);
     assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?"); 
     break;
   }
@@ -426,15 +426,15 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     // Compute the bits in the result that are not present in the input.
     unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
     
-    DemandedMask.trunc(SrcBitWidth);
-    KnownZero.trunc(SrcBitWidth);
-    KnownOne.trunc(SrcBitWidth);
+    DemandedMask = DemandedMask.trunc(SrcBitWidth);
+    KnownZero = KnownZero.trunc(SrcBitWidth);
+    KnownOne = KnownOne.trunc(SrcBitWidth);
     if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
                              KnownZero, KnownOne, Depth+1))
       return I;
-    DemandedMask.zext(BitWidth);
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    DemandedMask = DemandedMask.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?"); 
     // The top bits are known to be zero.
     KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
@@ -453,15 +453,15 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
     if ((NewBits & DemandedMask) != 0)
       InputDemandedBits.setBit(SrcBitWidth-1);
       
-    InputDemandedBits.trunc(SrcBitWidth);
-    KnownZero.trunc(SrcBitWidth);
-    KnownOne.trunc(SrcBitWidth);
+    InputDemandedBits = InputDemandedBits.trunc(SrcBitWidth);
+    KnownZero = KnownZero.trunc(SrcBitWidth);
+    KnownOne = KnownOne.trunc(SrcBitWidth);
     if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
                              KnownZero, KnownOne, Depth+1))
       return I;
-    InputDemandedBits.zext(BitWidth);
-    KnownZero.zext(BitWidth);
-    KnownOne.zext(BitWidth);
+    InputDemandedBits = InputDemandedBits.zext(BitWidth);
+    KnownZero = KnownZero.zext(BitWidth);
+    KnownOne = KnownOne.zext(BitWidth);
     assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?"); 
       
     // If the sign bit of the input is known set or clear, then we know the
diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 5d867e7154..318e212899 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -63,8 +63,8 @@ static Value *isBytewiseValue(Value *V) {
       while (Val.getBitWidth() != 8) {
         unsigned NextWidth = Val.getBitWidth()/2;
         Val2  = Val.lshr(NextWidth);
-        Val2.trunc(Val.getBitWidth()/2);
-        Val.trunc(Val.getBitWidth()/2);
+        Val2 = Val2.trunc(Val.getBitWidth()/2);
+        Val = Val.trunc(Val.getBitWidth()/2);
 
         // If the top/bottom halves aren't the same, reject it.
         if (Val != Val2)
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index eb58f7907c..2309f2274b 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -202,7 +202,7 @@ static Constant *ExtractConstantBytes(Constant *C, unsigned ByteStart,
     APInt V = CI->getValue();
     if (ByteStart)
       V = V.lshr(ByteStart*8);
-    V.trunc(ByteSize*8);
+    V = V.trunc(ByteSize*8);
     return ConstantInt::get(CI->getContext(), V);
   }
   
@@ -647,25 +647,22 @@ Constant *llvm::ConstantFoldCastInstruction(unsigned opc, Constant *V,
   case Instruction::ZExt:
     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
       uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
-      APInt Result(CI->getValue());
-      Result.zext(BitWidth);
-      return ConstantInt::get(V->getContext(), Result);
+      return ConstantInt::get(V->getContext(),
+                              CI->getValue().zext(BitWidth));
     }
     return 0;
   case Instruction::SExt:
     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
       uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
-      APInt Result(CI->getValue());
-      Result.sext(BitWidth);
-      return ConstantInt::get(V->getContext(), Result);
+      return ConstantInt::get(V->getContext(),
+                              CI->getValue().sext(BitWidth));
     }
     return 0;
   case Instruction::Trunc: {
     uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
     if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
-      APInt Result(CI->getValue());
-      Result.trunc(DestBitWidth);
-      return ConstantInt::get(V->getContext(), Result);
+      return ConstantInt::get(V->getContext(),
+                              CI->getValue().trunc(DestBitWidth));
     }
     
     // The input must be a constantexpr.  See if we can simplify this based on