Add const qualifiers to CodeGen's use of LLVM IR constructs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101334 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a613425..f734917 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -6288,7 +6288,7 @@
 /// FindBaseOffset - Return true if base is a frame index, which is known not
 // to alias with anything but itself.  Provides base object and offset as results.
 static bool FindBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset,
-                           GlobalValue *&GV, void *&CV) {
+                           const GlobalValue *&GV, void *&CV) {
   // Assume it is a primitive operation.
   Base = Ptr; Offset = 0; GV = 0; CV = 0;
 
@@ -6336,7 +6336,7 @@
   // Gather base node and offset information.
   SDValue Base1, Base2;
   int64_t Offset1, Offset2;
-  GlobalValue *GV1, *GV2;
+  const GlobalValue *GV1, *GV2;
   void *CV1, *CV2;
   bool isFrameIndex1 = FindBaseOffset(Ptr1, Base1, Offset1, GV1, CV1);
   bool isFrameIndex2 = FindBaseOffset(Ptr2, Base2, Offset2, GV2, CV2);
diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index fa0d998..c791c45 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -55,7 +55,7 @@
 #include "FunctionLoweringInfo.h"
 using namespace llvm;
 
-unsigned FastISel::getRegForValue(Value *V) {
+unsigned FastISel::getRegForValue(const Value *V) {
   EVT RealVT = TLI.getValueType(V->getType(), /*AllowUnknown=*/true);
   // Don't handle non-simple values in FastISel.
   if (!RealVT.isSimple())
@@ -83,7 +83,7 @@
   if (Reg != 0)
     return Reg;
 
-  if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+  if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     if (CI->getValue().getActiveBits() <= 64)
       Reg = FastEmit_i(VT, VT, ISD::Constant, CI->getZExtValue());
   } else if (isa<AllocaInst>(V)) {
@@ -93,7 +93,7 @@
     // local-CSE'd with actual integer zeros.
     Reg =
       getRegForValue(Constant::getNullValue(TD.getIntPtrType(V->getContext())));
-  } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
+  } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
     // Try to emit the constant directly.
     Reg = FastEmit_f(VT, VT, ISD::ConstantFP, CF);
 
@@ -116,7 +116,7 @@
           Reg = FastEmit_r(IntVT.getSimpleVT(), VT, ISD::SINT_TO_FP, IntegerReg);
       }
     }
-  } else if (Operator *Op = dyn_cast<Operator>(V)) {
+  } else if (const Operator *Op = dyn_cast<Operator>(V)) {
     if (!SelectOperator(Op, Op->getOpcode())) return 0;
     Reg = LocalValueMap[Op];
   } else if (isa<UndefValue>(V)) {
@@ -136,7 +136,7 @@
   return Reg;
 }
 
-unsigned FastISel::lookUpRegForValue(Value *V) {
+unsigned FastISel::lookUpRegForValue(const Value *V) {
   // Look up the value to see if we already have a register for it. We
   // cache values defined by Instructions across blocks, and other values
   // only locally. This is because Instructions already have the SSA
@@ -152,7 +152,7 @@
 /// NOTE: This is only necessary because we might select a block that uses
 /// a value before we select the block that defines the value.  It might be
 /// possible to fix this by selecting blocks in reverse postorder.
-unsigned FastISel::UpdateValueMap(Value* I, unsigned Reg) {
+unsigned FastISel::UpdateValueMap(const Value *I, unsigned Reg) {
   if (!isa<Instruction>(I)) {
     LocalValueMap[I] = Reg;
     return Reg;
@@ -169,7 +169,7 @@
   return AssignedReg;
 }
 
-unsigned FastISel::getRegForGEPIndex(Value *Idx) {
+unsigned FastISel::getRegForGEPIndex(const Value *Idx) {
   unsigned IdxN = getRegForValue(Idx);
   if (IdxN == 0)
     // Unhandled operand. Halt "fast" selection and bail.
@@ -188,7 +188,7 @@
 /// SelectBinaryOp - Select and emit code for a binary operator instruction,
 /// which has an opcode which directly corresponds to the given ISD opcode.
 ///
-bool FastISel::SelectBinaryOp(User *I, unsigned ISDOpcode) {
+bool FastISel::SelectBinaryOp(const User *I, unsigned ISDOpcode) {
   EVT VT = EVT::getEVT(I->getType(), /*HandleUnknown=*/true);
   if (VT == MVT::Other || !VT.isSimple())
     // Unhandled type. Halt "fast" selection and bail.
@@ -254,7 +254,7 @@
   return true;
 }
 
-bool FastISel::SelectGetElementPtr(User *I) {
+bool FastISel::SelectGetElementPtr(const User *I) {
   unsigned N = getRegForValue(I->getOperand(0));
   if (N == 0)
     // Unhandled operand. Halt "fast" selection and bail.
@@ -262,9 +262,9 @@
 
   const Type *Ty = I->getOperand(0)->getType();
   MVT VT = TLI.getPointerTy();
-  for (GetElementPtrInst::op_iterator OI = I->op_begin()+1, E = I->op_end();
-       OI != E; ++OI) {
-    Value *Idx = *OI;
+  for (GetElementPtrInst::const_op_iterator OI = I->op_begin()+1,
+       E = I->op_end(); OI != E; ++OI) {
+    const Value *Idx = *OI;
     if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
       unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
       if (Field) {
@@ -282,7 +282,7 @@
       Ty = cast<SequentialType>(Ty)->getElementType();
 
       // If this is a constant subscript, handle it quickly.
-      if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
+      if (const ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
         if (CI->getZExtValue() == 0) continue;
         uint64_t Offs = 
           TD.getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
@@ -318,8 +318,8 @@
   return true;
 }
 
-bool FastISel::SelectCall(User *I) {
-  Function *F = cast<CallInst>(I)->getCalledFunction();
+bool FastISel::SelectCall(const User *I) {
+  const Function *F = cast<CallInst>(I)->getCalledFunction();
   if (!F) return false;
 
   // Handle selected intrinsic function calls.
@@ -327,17 +327,17 @@
   switch (IID) {
   default: break;
   case Intrinsic::dbg_declare: {
-    DbgDeclareInst *DI = cast<DbgDeclareInst>(I);
+    const DbgDeclareInst *DI = cast<DbgDeclareInst>(I);
     if (!DIDescriptor::ValidDebugInfo(DI->getVariable(), CodeGenOpt::None) ||
         !MF.getMMI().hasDebugInfo())
       return true;
 
-    Value *Address = DI->getAddress();
+    const Value *Address = DI->getAddress();
     if (!Address)
       return true;
     if (isa<UndefValue>(Address))
       return true;
-    AllocaInst *AI = dyn_cast<AllocaInst>(Address);
+    const AllocaInst *AI = dyn_cast<AllocaInst>(Address);
     // Don't handle byval struct arguments or VLAs, for example.
     if (!AI) break;
     DenseMap<const AllocaInst*, int>::iterator SI =
@@ -354,18 +354,18 @@
   }
   case Intrinsic::dbg_value: {
     // This form of DBG_VALUE is target-independent.
-    DbgValueInst *DI = cast<DbgValueInst>(I);
+    const DbgValueInst *DI = cast<DbgValueInst>(I);
     const TargetInstrDesc &II = TII.get(TargetOpcode::DBG_VALUE);
-    Value *V = DI->getValue();
+    const Value *V = DI->getValue();
     if (!V) {
       // Currently the optimizer can produce this; insert an undef to
       // help debugging.  Probably the optimizer should not do this.
       BuildMI(MBB, DL, II).addReg(0U).addImm(DI->getOffset()).
                                      addMetadata(DI->getVariable());
-    } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+    } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
       BuildMI(MBB, DL, II).addImm(CI->getZExtValue()).addImm(DI->getOffset()).
                                      addMetadata(DI->getVariable());
-    } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
+    } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
       BuildMI(MBB, DL, II).addFPImm(CF).addImm(DI->getOffset()).
                                      addMetadata(DI->getVariable());
     } else if (unsigned Reg = lookUpRegForValue(V)) {
@@ -448,7 +448,7 @@
   return false;
 }
 
-bool FastISel::SelectCast(User *I, unsigned Opcode) {
+bool FastISel::SelectCast(const User *I, unsigned Opcode) {
   EVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
   EVT DstVT = TLI.getValueType(I->getType());
     
@@ -500,7 +500,7 @@
   return true;
 }
 
-bool FastISel::SelectBitCast(User *I) {
+bool FastISel::SelectBitCast(const User *I) {
   // If the bitcast doesn't change the type, just use the operand value.
   if (I->getType() == I->getOperand(0)->getType()) {
     unsigned Reg = getRegForValue(I->getOperand(0));
@@ -551,7 +551,7 @@
 }
 
 bool
-FastISel::SelectInstruction(Instruction *I) {
+FastISel::SelectInstruction(const Instruction *I) {
   // First, try doing target-independent selection.
   if (SelectOperator(I, I->getOpcode()))
     return true;
@@ -580,7 +580,7 @@
 /// SelectFNeg - Emit an FNeg operation.
 ///
 bool
-FastISel::SelectFNeg(User *I) {
+FastISel::SelectFNeg(const User *I) {
   unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I));
   if (OpReg == 0) return false;
 
@@ -621,7 +621,7 @@
 }
 
 bool
-FastISel::SelectOperator(User *I, unsigned Opcode) {
+FastISel::SelectOperator(const User *I, unsigned Opcode) {
   switch (Opcode) {
   case Instruction::Add:
     return SelectBinaryOp(I, ISD::ADD);
@@ -667,10 +667,10 @@
     return SelectGetElementPtr(I);
 
   case Instruction::Br: {
-    BranchInst *BI = cast<BranchInst>(I);
+    const BranchInst *BI = cast<BranchInst>(I);
 
     if (BI->isUnconditional()) {
-      BasicBlock *LLVMSucc = BI->getSuccessor(0);
+      const BasicBlock *LLVMSucc = BI->getSuccessor(0);
       MachineBasicBlock *MSucc = MBBMap[LLVMSucc];
       FastEmitBranch(MSucc);
       return true;
@@ -782,7 +782,7 @@
 }
 
 unsigned FastISel::FastEmit_f(MVT, MVT,
-                              unsigned, ConstantFP * /*FPImm*/) {
+                              unsigned, const ConstantFP * /*FPImm*/) {
   return 0;
 }
 
@@ -794,7 +794,7 @@
 
 unsigned FastISel::FastEmit_rf(MVT, MVT,
                                unsigned, unsigned /*Op0*/,
-                               ConstantFP * /*FPImm*/) {
+                               const ConstantFP * /*FPImm*/) {
   return 0;
 }
 
@@ -827,7 +827,7 @@
 /// FastEmit_rf. If that fails, it materializes the immediate into a register
 /// and try FastEmit_rr instead.
 unsigned FastISel::FastEmit_rf_(MVT VT, unsigned Opcode,
-                                unsigned Op0, ConstantFP *FPImm,
+                                unsigned Op0, const ConstantFP *FPImm,
                                 MVT ImmType) {
   // First check if immediate type is legal. If not, we can't use the rf form.
   unsigned ResultReg = FastEmit_rf(VT, VT, Opcode, Op0, FPImm);
@@ -937,7 +937,7 @@
 
 unsigned FastISel::FastEmitInst_rf(unsigned MachineInstOpcode,
                                    const TargetRegisterClass *RC,
-                                   unsigned Op0, ConstantFP *FPImm) {
+                                   unsigned Op0, const ConstantFP *FPImm) {
   unsigned ResultReg = createResultReg(RC);
   const TargetInstrDesc &II = TII.get(MachineInstOpcode);
 
diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index f88cfb0..77b5790 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -316,7 +316,7 @@
 
   // Gather all the type infos for this landing pad and pass them along to
   // MachineModuleInfo.
-  std::vector<GlobalVariable *> TyInfo;
+  std::vector<const GlobalVariable *> TyInfo;
   unsigned N = I.getNumOperands();
 
   for (unsigned i = N - 1; i > 2; --i) {
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 9495f82..75557e7 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -531,10 +531,10 @@
       AddOperand(&*MIB, Op, (*MIB).getNumOperands(), &II, VRBaseMap,
                  true /*IsDebug*/);
   } else if (SD->getKind() == SDDbgValue::CONST) {
-    Value *V = SD->getConst();
-    if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+    const Value *V = SD->getConst();
+    if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
       MIB.addImm(CI->getSExtValue());
-    } else if (ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
+    } else if (const ConstantFP *CF = dyn_cast<ConstantFP>(V)) {
       MIB.addFPImm(CF);
     } else {
       // Could be an Undef.  In any case insert an Undef so we can see what we
diff --git a/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h b/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
index 9d1568f..ac2d338 100644
--- a/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
+++ b/lib/CodeGen/SelectionDAG/SDNodeDbgValue.h
@@ -41,7 +41,7 @@
       SDNode *Node;         // valid for expressions
       unsigned ResNo;       // valid for expressions
     } s;
-    Value *Const;           // valid for constants
+    const Value *Const;     // valid for constants
     unsigned FrameIx;       // valid for stack objects
   } u;
   MDNode *mdPtr;
@@ -60,7 +60,8 @@
   }
 
   // Constructor for constants.
-  SDDbgValue(MDNode *mdP, Value *C, uint64_t off, DebugLoc dl, unsigned O) : 
+  SDDbgValue(MDNode *mdP, const Value *C, uint64_t off, DebugLoc dl,
+             unsigned O) : 
     mdPtr(mdP), Offset(off), DL(dl), Order(O), Invalid(false) {
     kind = CONST;
     u.Const = C;
@@ -86,7 +87,7 @@
   unsigned getResNo() { assert (kind==SDNODE); return u.s.ResNo; }
 
   // Returns the Value* for a constant
-  Value *getConst() { assert (kind==CONST); return u.Const; }
+  const Value *getConst() { assert (kind==CONST); return u.Const; }
 
   // Returns the FrameIx for a stack object
   unsigned getFrameIx() { assert (kind==FRAMEIX); return u.FrameIx; }
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index b917fca..1afb418 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1048,7 +1048,7 @@
   return SDValue(N, 0);
 }
 
-SDValue SelectionDAG::getConstantPool(Constant *C, EVT VT,
+SDValue SelectionDAG::getConstantPool(const Constant *C, EVT VT,
                                       unsigned Alignment, int Offset,
                                       bool isTarget,
                                       unsigned char TargetFlags) {
@@ -1319,7 +1319,7 @@
 }
 
 
-SDValue SelectionDAG::getBlockAddress(BlockAddress *BA, EVT VT,
+SDValue SelectionDAG::getBlockAddress(const BlockAddress *BA, EVT VT,
                                       bool isTarget,
                                       unsigned char TargetFlags) {
   unsigned Opc = isTarget ? ISD::TargetBlockAddress : ISD::BlockAddress;
@@ -2270,7 +2270,7 @@
   GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op);
   if (!GA) return false;
   if (GA->getOffset() != 0) return false;
-  GlobalVariable *GV = dyn_cast<GlobalVariable>(GA->getGlobal());
+  const GlobalVariable *GV = dyn_cast<GlobalVariable>(GA->getGlobal());
   if (!GV) return false;
   return MF->getMMI().hasDebugInfo();
 }
@@ -3195,7 +3195,7 @@
   if (!G)
     return false;
 
-  GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getGlobal());
+  const GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getGlobal());
   if (GV && GetConstantStringInfo(GV, Str, SrcDelta, false))
     return true;
 
@@ -4935,7 +4935,7 @@
 }
 
 SDDbgValue *
-SelectionDAG::getDbgValue(MDNode *MDPtr, Value *C, uint64_t Off,
+SelectionDAG::getDbgValue(MDNode *MDPtr, const Value *C, uint64_t Off,
                           DebugLoc DL, unsigned O) {
   return new (Allocator) SDDbgValue(MDPtr, C, Off, DL, O);
 }
@@ -6169,8 +6169,8 @@
       return true;
   }
 
-  GlobalValue *GV1 = NULL;
-  GlobalValue *GV2 = NULL;
+  const GlobalValue *GV1 = NULL;
+  const GlobalValue *GV2 = NULL;
   int64_t Offset1 = 0;
   int64_t Offset2 = 0;
   bool isGA1 = TLI.isGAPlusOffset(Loc.getNode(), GV1, Offset1);
@@ -6185,14 +6185,14 @@
 /// it cannot be inferred.
 unsigned SelectionDAG::InferPtrAlignment(SDValue Ptr) const {
   // If this is a GlobalAddress + cst, return the alignment.
-  GlobalValue *GV;
+  const GlobalValue *GV;
   int64_t GVOffset = 0;
   if (TLI.isGAPlusOffset(Ptr.getNode(), GV, GVOffset)) {
     // If GV has specified alignment, then use it. Otherwise, use the preferred
     // alignment.
     unsigned Align = GV->getAlignment();
     if (!Align) {
-      if (GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
+      if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV)) {
         if (GVar->hasInitializer()) {
           const TargetData *TD = TLI.getTargetData();
           Align = TD->getPreferredAlignment(GVar);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 7807841..8aa4ac3 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -613,11 +613,11 @@
     AssignOrderingToNode(Node->getOperand(I).getNode());
 }
 
-void SelectionDAGBuilder::visit(Instruction &I) {
+void SelectionDAGBuilder::visit(const Instruction &I) {
   visit(I.getOpcode(), I);
 }
 
-void SelectionDAGBuilder::visit(unsigned Opcode, User &I) {
+void SelectionDAGBuilder::visit(unsigned Opcode, const User &I) {
   // Note: this doesn't use InstVisitor, because it has to work with
   // ConstantExpr's in addition to instructions.
   switch (Opcode) {
@@ -812,7 +812,7 @@
   }
 }
 
-void SelectionDAGBuilder::visitRet(ReturnInst &I) {
+void SelectionDAGBuilder::visitRet(const ReturnInst &I) {
   SDValue Chain = getControlRoot();
   SmallVector<ISD::OutputArg, 8> Outs;
   FunctionLoweringInfo &FLI = DAG.getFunctionLoweringInfo();
@@ -917,7 +917,7 @@
 /// CopyToExportRegsIfNeeded - If the given value has virtual registers
 /// created for it, emit nodes to copy the value into the virtual
 /// registers.
-void SelectionDAGBuilder::CopyToExportRegsIfNeeded(Value *V) {
+void SelectionDAGBuilder::CopyToExportRegsIfNeeded(const Value *V) {
   if (!V->use_empty()) {
     DenseMap<const Value *, unsigned>::iterator VMI = FuncInfo.ValueMap.find(V);
     if (VMI != FuncInfo.ValueMap.end())
@@ -928,7 +928,7 @@
 /// ExportFromCurrentBlock - If this condition isn't known to be exported from
 /// the current basic block, add it to ValueMap now so that we'll get a
 /// CopyTo/FromReg.
-void SelectionDAGBuilder::ExportFromCurrentBlock(Value *V) {
+void SelectionDAGBuilder::ExportFromCurrentBlock(const Value *V) {
   // No need to export constants.
   if (!isa<Instruction>(V) && !isa<Argument>(V)) return;
 
@@ -939,11 +939,11 @@
   CopyValueToVirtualRegister(V, Reg);
 }
 
-bool SelectionDAGBuilder::isExportableFromCurrentBlock(Value *V,
+bool SelectionDAGBuilder::isExportableFromCurrentBlock(const Value *V,
                                                      const BasicBlock *FromBB) {
   // The operands of the setcc have to be in this block.  We don't know
   // how to export them from some other block.
-  if (Instruction *VI = dyn_cast<Instruction>(V)) {
+  if (const Instruction *VI = dyn_cast<Instruction>(V)) {
     // Can export from current BB.
     if (VI->getParent() == FromBB)
       return true;
@@ -977,7 +977,7 @@
 /// AND operator tree.
 ///
 void
-SelectionDAGBuilder::EmitBranchForMergedCondition(Value *Cond,
+SelectionDAGBuilder::EmitBranchForMergedCondition(const Value *Cond,
                                                   MachineBasicBlock *TBB,
                                                   MachineBasicBlock *FBB,
                                                   MachineBasicBlock *CurBB) {
@@ -985,7 +985,7 @@
 
   // If the leaf of the tree is a comparison, merge the condition into
   // the caseblock.
-  if (CmpInst *BOp = dyn_cast<CmpInst>(Cond)) {
+  if (const CmpInst *BOp = dyn_cast<CmpInst>(Cond)) {
     // The operands of the cmp have to be in this block.  We don't know
     // how to export them from some other block.  If this is the first block
     // of the sequence, no exporting is needed.
@@ -993,9 +993,9 @@
         (isExportableFromCurrentBlock(BOp->getOperand(0), BB) &&
          isExportableFromCurrentBlock(BOp->getOperand(1), BB))) {
       ISD::CondCode Condition;
-      if (ICmpInst *IC = dyn_cast<ICmpInst>(Cond)) {
+      if (const ICmpInst *IC = dyn_cast<ICmpInst>(Cond)) {
         Condition = getICmpCondCode(IC->getPredicate());
-      } else if (FCmpInst *FC = dyn_cast<FCmpInst>(Cond)) {
+      } else if (const FCmpInst *FC = dyn_cast<FCmpInst>(Cond)) {
         Condition = getFCmpCondCode(FC->getPredicate());
       } else {
         Condition = ISD::SETEQ; // silence warning.
@@ -1016,13 +1016,13 @@
 }
 
 /// FindMergedConditions - If Cond is an expression like
-void SelectionDAGBuilder::FindMergedConditions(Value *Cond,
+void SelectionDAGBuilder::FindMergedConditions(const Value *Cond,
                                                MachineBasicBlock *TBB,
                                                MachineBasicBlock *FBB,
                                                MachineBasicBlock *CurBB,
                                                unsigned Opc) {
   // If this node is not part of the or/and tree, emit it as a branch.
-  Instruction *BOp = dyn_cast<Instruction>(Cond);
+  const Instruction *BOp = dyn_cast<Instruction>(Cond);
   if (!BOp || !(isa<BinaryOperator>(BOp) || isa<CmpInst>(BOp)) ||
       (unsigned)BOp->getOpcode() != Opc || !BOp->hasOneUse() ||
       BOp->getParent() != CurBB->getBasicBlock() ||
@@ -1102,7 +1102,7 @@
   return true;
 }
 
-void SelectionDAGBuilder::visitBr(BranchInst &I) {
+void SelectionDAGBuilder::visitBr(const BranchInst &I) {
   // Update machine-CFG edges.
   MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[I.getSuccessor(0)];
 
@@ -1127,7 +1127,7 @@
 
   // If this condition is one of the special cases we handle, do special stuff
   // now.
-  Value *CondVal = I.getCondition();
+  const Value *CondVal = I.getCondition();
   MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)];
 
   // If this is a series of conditions that are or'd or and'd together, emit
@@ -1145,7 +1145,7 @@
   //     cmp D, E
   //     jle foo
   //
-  if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(CondVal)) {
+  if (const BinaryOperator *BOp = dyn_cast<BinaryOperator>(CondVal)) {
     if (BOp->hasOneUse() &&
         (BOp->getOpcode() == Instruction::And ||
          BOp->getOpcode() == Instruction::Or)) {
@@ -1417,7 +1417,7 @@
   DAG.setRoot(BrAnd);
 }
 
-void SelectionDAGBuilder::visitInvoke(InvokeInst &I) {
+void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
   // Retrieve successors.
   MachineBasicBlock *Return = FuncInfo.MBBMap[I.getSuccessor(0)];
   MachineBasicBlock *LandingPad = FuncInfo.MBBMap[I.getSuccessor(1)];
@@ -1442,14 +1442,14 @@
                           DAG.getBasicBlock(Return)));
 }
 
-void SelectionDAGBuilder::visitUnwind(UnwindInst &I) {
+void SelectionDAGBuilder::visitUnwind(const UnwindInst &I) {
 }
 
 /// handleSmallSwitchCaseRange - Emit a series of specific tests (suitable for
 /// small case ranges).
 bool SelectionDAGBuilder::handleSmallSwitchRange(CaseRec& CR,
                                                  CaseRecVector& WorkList,
-                                                 Value* SV,
+                                                 const Value* SV,
                                                  MachineBasicBlock* Default) {
   Case& BackCase  = *(CR.Range.second-1);
 
@@ -1503,7 +1503,7 @@
       FallThrough = Default;
     }
 
-    Value *RHS, *LHS, *MHS;
+    const Value *RHS, *LHS, *MHS;
     ISD::CondCode CC;
     if (I->High == I->Low) {
       // This is just small small case range :) containing exactly 1 case
@@ -1546,7 +1546,7 @@
 /// handleJTSwitchCase - Emit jumptable for current switch case range
 bool SelectionDAGBuilder::handleJTSwitchCase(CaseRec& CR,
                                              CaseRecVector& WorkList,
-                                             Value* SV,
+                                             const Value* SV,
                                              MachineBasicBlock* Default) {
   Case& FrontCase = *CR.Range.first;
   Case& BackCase  = *(CR.Range.second-1);
@@ -1641,7 +1641,7 @@
 /// 2 subtrees.
 bool SelectionDAGBuilder::handleBTSplitSwitchCase(CaseRec& CR,
                                                   CaseRecVector& WorkList,
-                                                  Value* SV,
+                                                  const Value* SV,
                                                   MachineBasicBlock* Default) {
   // Get the MachineFunction which holds the current MBB.  This is used when
   // inserting any additional MBBs necessary to represent the switch.
@@ -1769,7 +1769,7 @@
 /// of masks and emit bit tests with these masks.
 bool SelectionDAGBuilder::handleBitTestsSwitchCase(CaseRec& CR,
                                                    CaseRecVector& WorkList,
-                                                   Value* SV,
+                                                   const Value* SV,
                                                    MachineBasicBlock* Default){
   EVT PTy = TLI.getPointerTy();
   unsigned IntPtrBits = PTy.getSizeInBits();
@@ -1939,7 +1939,7 @@
   return numCmps;
 }
 
-void SelectionDAGBuilder::visitSwitch(SwitchInst &SI) {
+void SelectionDAGBuilder::visitSwitch(const SwitchInst &SI) {
   // Figure out which block is immediately after the current one.
   MachineBasicBlock *NextBlock = 0;
   MachineBasicBlock *Default = FuncInfo.MBBMap[SI.getDefaultDest()];
@@ -1971,7 +1971,7 @@
   // Get the Value to be switched on and default basic blocks, which will be
   // inserted into CaseBlock records, representing basic blocks in the binary
   // search tree.
-  Value *SV = SI.getOperand(0);
+  const Value *SV = SI.getOperand(0);
 
   // Push the initial CaseRec onto the worklist
   CaseRecVector WorkList;
@@ -2002,7 +2002,7 @@
   }
 }
 
-void SelectionDAGBuilder::visitIndirectBr(IndirectBrInst &I) {
+void SelectionDAGBuilder::visitIndirectBr(const IndirectBrInst &I) {
   // Update machine-CFG edges with unique successors.
   SmallVector<BasicBlock*, 32> succs;
   succs.reserve(I.getNumSuccessors());
@@ -2018,7 +2018,7 @@
                           getValue(I.getAddress())));
 }
 
-void SelectionDAGBuilder::visitFSub(User &I) {
+void SelectionDAGBuilder::visitFSub(const User &I) {
   // -0.0 - X --> fneg
   const Type *Ty = I.getType();
   if (Ty->isVectorTy()) {
@@ -2048,14 +2048,14 @@
   visitBinary(I, ISD::FSUB);
 }
 
-void SelectionDAGBuilder::visitBinary(User &I, unsigned OpCode) {
+void SelectionDAGBuilder::visitBinary(const User &I, unsigned OpCode) {
   SDValue Op1 = getValue(I.getOperand(0));
   SDValue Op2 = getValue(I.getOperand(1));
   setValue(&I, DAG.getNode(OpCode, getCurDebugLoc(),
                            Op1.getValueType(), Op1, Op2));
 }
 
-void SelectionDAGBuilder::visitShift(User &I, unsigned Opcode) {
+void SelectionDAGBuilder::visitShift(const User &I, unsigned Opcode) {
   SDValue Op1 = getValue(I.getOperand(0));
   SDValue Op2 = getValue(I.getOperand(1));
   if (!I.getType()->isVectorTy() &&
@@ -2089,11 +2089,11 @@
                            Op1.getValueType(), Op1, Op2));
 }
 
-void SelectionDAGBuilder::visitICmp(User &I) {
+void SelectionDAGBuilder::visitICmp(const User &I) {
   ICmpInst::Predicate predicate = ICmpInst::BAD_ICMP_PREDICATE;
-  if (ICmpInst *IC = dyn_cast<ICmpInst>(&I))
+  if (const ICmpInst *IC = dyn_cast<ICmpInst>(&I))
     predicate = IC->getPredicate();
-  else if (ConstantExpr *IC = dyn_cast<ConstantExpr>(&I))
+  else if (const ConstantExpr *IC = dyn_cast<ConstantExpr>(&I))
     predicate = ICmpInst::Predicate(IC->getPredicate());
   SDValue Op1 = getValue(I.getOperand(0));
   SDValue Op2 = getValue(I.getOperand(1));
@@ -2103,11 +2103,11 @@
   setValue(&I, DAG.getSetCC(getCurDebugLoc(), DestVT, Op1, Op2, Opcode));
 }
 
-void SelectionDAGBuilder::visitFCmp(User &I) {
+void SelectionDAGBuilder::visitFCmp(const User &I) {
   FCmpInst::Predicate predicate = FCmpInst::BAD_FCMP_PREDICATE;
-  if (FCmpInst *FC = dyn_cast<FCmpInst>(&I))
+  if (const FCmpInst *FC = dyn_cast<FCmpInst>(&I))
     predicate = FC->getPredicate();
-  else if (ConstantExpr *FC = dyn_cast<ConstantExpr>(&I))
+  else if (const ConstantExpr *FC = dyn_cast<ConstantExpr>(&I))
     predicate = FCmpInst::Predicate(FC->getPredicate());
   SDValue Op1 = getValue(I.getOperand(0));
   SDValue Op2 = getValue(I.getOperand(1));
@@ -2116,7 +2116,7 @@
   setValue(&I, DAG.getSetCC(getCurDebugLoc(), DestVT, Op1, Op2, Condition));
 }
 
-void SelectionDAGBuilder::visitSelect(User &I) {
+void SelectionDAGBuilder::visitSelect(const User &I) {
   SmallVector<EVT, 4> ValueVTs;
   ComputeValueVTs(TLI, I.getType(), ValueVTs);
   unsigned NumValues = ValueVTs.size();
@@ -2141,14 +2141,14 @@
                            &Values[0], NumValues));
 }
 
-void SelectionDAGBuilder::visitTrunc(User &I) {
+void SelectionDAGBuilder::visitTrunc(const User &I) {
   // TruncInst cannot be a no-op cast because sizeof(src) > sizeof(dest).
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::TRUNCATE, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitZExt(User &I) {
+void SelectionDAGBuilder::visitZExt(const User &I) {
   // ZExt cannot be a no-op cast because sizeof(src) < sizeof(dest).
   // ZExt also can't be a cast to bool for same reason. So, nothing much to do
   SDValue N = getValue(I.getOperand(0));
@@ -2156,7 +2156,7 @@
   setValue(&I, DAG.getNode(ISD::ZERO_EXTEND, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitSExt(User &I) {
+void SelectionDAGBuilder::visitSExt(const User &I) {
   // SExt cannot be a no-op cast because sizeof(src) < sizeof(dest).
   // SExt also can't be a cast to bool for same reason. So, nothing much to do
   SDValue N = getValue(I.getOperand(0));
@@ -2164,7 +2164,7 @@
   setValue(&I, DAG.getNode(ISD::SIGN_EXTEND, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitFPTrunc(User &I) {
+void SelectionDAGBuilder::visitFPTrunc(const User &I) {
   // FPTrunc is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
@@ -2172,42 +2172,42 @@
                            DestVT, N, DAG.getIntPtrConstant(0)));
 }
 
-void SelectionDAGBuilder::visitFPExt(User &I){
+void SelectionDAGBuilder::visitFPExt(const User &I){
   // FPTrunc is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::FP_EXTEND, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitFPToUI(User &I) {
+void SelectionDAGBuilder::visitFPToUI(const User &I) {
   // FPToUI is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::FP_TO_UINT, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitFPToSI(User &I) {
+void SelectionDAGBuilder::visitFPToSI(const User &I) {
   // FPToSI is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::FP_TO_SINT, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitUIToFP(User &I) {
+void SelectionDAGBuilder::visitUIToFP(const User &I) {
   // UIToFP is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::UINT_TO_FP, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitSIToFP(User &I){
+void SelectionDAGBuilder::visitSIToFP(const User &I){
   // SIToFP is never a no-op cast, no need to check
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
   setValue(&I, DAG.getNode(ISD::SINT_TO_FP, getCurDebugLoc(), DestVT, N));
 }
 
-void SelectionDAGBuilder::visitPtrToInt(User &I) {
+void SelectionDAGBuilder::visitPtrToInt(const User &I) {
   // What to do depends on the size of the integer and the size of the pointer.
   // We can either truncate, zero extend, or no-op, accordingly.
   SDValue N = getValue(I.getOperand(0));
@@ -2216,7 +2216,7 @@
   setValue(&I, DAG.getZExtOrTrunc(N, getCurDebugLoc(), DestVT));
 }
 
-void SelectionDAGBuilder::visitIntToPtr(User &I) {
+void SelectionDAGBuilder::visitIntToPtr(const User &I) {
   // What to do depends on the size of the integer and the size of the pointer.
   // We can either truncate, zero extend, or no-op, accordingly.
   SDValue N = getValue(I.getOperand(0));
@@ -2225,7 +2225,7 @@
   setValue(&I, DAG.getZExtOrTrunc(N, getCurDebugLoc(), DestVT));
 }
 
-void SelectionDAGBuilder::visitBitCast(User &I) {
+void SelectionDAGBuilder::visitBitCast(const User &I) {
   SDValue N = getValue(I.getOperand(0));
   EVT DestVT = TLI.getValueType(I.getType());
 
@@ -2238,7 +2238,7 @@
     setValue(&I, N);            // noop cast.
 }
 
-void SelectionDAGBuilder::visitInsertElement(User &I) {
+void SelectionDAGBuilder::visitInsertElement(const User &I) {
   SDValue InVec = getValue(I.getOperand(0));
   SDValue InVal = getValue(I.getOperand(1));
   SDValue InIdx = DAG.getNode(ISD::ZERO_EXTEND, getCurDebugLoc(),
@@ -2249,7 +2249,7 @@
                            InVec, InVal, InIdx));
 }
 
-void SelectionDAGBuilder::visitExtractElement(User &I) {
+void SelectionDAGBuilder::visitExtractElement(const User &I) {
   SDValue InVec = getValue(I.getOperand(0));
   SDValue InIdx = DAG.getNode(ISD::ZERO_EXTEND, getCurDebugLoc(),
                               TLI.getPointerTy(),
@@ -2268,7 +2268,7 @@
   return true;
 }
 
-void SelectionDAGBuilder::visitShuffleVector(User &I) {
+void SelectionDAGBuilder::visitShuffleVector(const User &I) {
   SmallVector<int, 8> Mask;
   SDValue Src1 = getValue(I.getOperand(0));
   SDValue Src2 = getValue(I.getOperand(1));
@@ -2449,7 +2449,7 @@
                            VT, &Ops[0], Ops.size()));
 }
 
-void SelectionDAGBuilder::visitInsertValue(InsertValueInst &I) {
+void SelectionDAGBuilder::visitInsertValue(const InsertValueInst &I) {
   const Value *Op0 = I.getOperand(0);
   const Value *Op1 = I.getOperand(1);
   const Type *AggTy = I.getType();
@@ -2490,7 +2490,7 @@
                            &Values[0], NumAggValues));
 }
 
-void SelectionDAGBuilder::visitExtractValue(ExtractValueInst &I) {
+void SelectionDAGBuilder::visitExtractValue(const ExtractValueInst &I) {
   const Value *Op0 = I.getOperand(0);
   const Type *AggTy = Op0->getType();
   const Type *ValTy = I.getType();
@@ -2518,13 +2518,13 @@
                            &Values[0], NumValValues));
 }
 
-void SelectionDAGBuilder::visitGetElementPtr(User &I) {
+void SelectionDAGBuilder::visitGetElementPtr(const User &I) {
   SDValue N = getValue(I.getOperand(0));
   const Type *Ty = I.getOperand(0)->getType();
 
-  for (GetElementPtrInst::op_iterator OI = I.op_begin()+1, E = I.op_end();
+  for (GetElementPtrInst::const_op_iterator OI = I.op_begin()+1, E = I.op_end();
        OI != E; ++OI) {
-    Value *Idx = *OI;
+    const Value *Idx = *OI;
     if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
       unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
       if (Field) {
@@ -2544,7 +2544,7 @@
       Ty = cast<SequentialType>(Ty)->getElementType();
 
       // If this is a constant subscript, handle it quickly.
-      if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
+      if (const ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
         if (CI->getZExtValue() == 0) continue;
         uint64_t Offs =
             TD->getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
@@ -2595,7 +2595,7 @@
   setValue(&I, N);
 }
 
-void SelectionDAGBuilder::visitAlloca(AllocaInst &I) {
+void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
   // If this is a fixed sized alloca in the entry block of the function,
   // allocate it statically on the stack.
   if (FuncInfo.StaticAllocaMap.count(&I))
@@ -2647,7 +2647,7 @@
   FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject();
 }
 
-void SelectionDAGBuilder::visitLoad(LoadInst &I) {
+void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
   const Value *SV = I.getOperand(0);
   SDValue Ptr = getValue(SV);
 
@@ -2707,9 +2707,9 @@
                            &Values[0], NumValues));
 }
 
-void SelectionDAGBuilder::visitStore(StoreInst &I) {
-  Value *SrcV = I.getOperand(0);
-  Value *PtrV = I.getOperand(1);
+void SelectionDAGBuilder::visitStore(const StoreInst &I) {
+  const Value *SrcV = I.getOperand(0);
+  const Value *PtrV = I.getOperand(1);
 
   SmallVector<EVT, 4> ValueVTs;
   SmallVector<uint64_t, 4> Offsets;
@@ -2746,7 +2746,7 @@
 
 /// visitTargetIntrinsic - Lower a call of a target intrinsic to an INTRINSIC
 /// node.
-void SelectionDAGBuilder::visitTargetIntrinsic(CallInst &I,
+void SelectionDAGBuilder::visitTargetIntrinsic(const CallInst &I,
                                                unsigned Intrinsic) {
   bool HasChain = !I.doesNotAccessMemory();
   bool OnlyLoad = HasChain && I.onlyReadsMemory();
@@ -2872,7 +2872,8 @@
 /// visitIntrinsicCall: I is a call instruction
 ///                     Op is the associated NodeType for I
 const char *
-SelectionDAGBuilder::implVisitBinaryAtomic(CallInst& I, ISD::NodeType Op) {
+SelectionDAGBuilder::implVisitBinaryAtomic(const CallInst& I,
+                                           ISD::NodeType Op) {
   SDValue Root = getRoot();
   SDValue L =
     DAG.getAtomic(Op, getCurDebugLoc(),
@@ -2888,7 +2889,7 @@
 
 // implVisitAluOverflow - Lower arithmetic overflow instrinsics.
 const char *
-SelectionDAGBuilder::implVisitAluOverflow(CallInst &I, ISD::NodeType Op) {
+SelectionDAGBuilder::implVisitAluOverflow(const CallInst &I, ISD::NodeType Op) {
   SDValue Op1 = getValue(I.getOperand(1));
   SDValue Op2 = getValue(I.getOperand(2));
 
@@ -2900,7 +2901,7 @@
 /// visitExp - Lower an exp intrinsic. Handles the special sequences for
 /// limited-precision mode.
 void
-SelectionDAGBuilder::visitExp(CallInst &I) {
+SelectionDAGBuilder::visitExp(const CallInst &I) {
   SDValue result;
   DebugLoc dl = getCurDebugLoc();
 
@@ -3026,7 +3027,7 @@
 /// visitLog - Lower a log intrinsic. Handles the special sequences for
 /// limited-precision mode.
 void
-SelectionDAGBuilder::visitLog(CallInst &I) {
+SelectionDAGBuilder::visitLog(const CallInst &I) {
   SDValue result;
   DebugLoc dl = getCurDebugLoc();
 
@@ -3136,7 +3137,7 @@
 /// visitLog2 - Lower a log2 intrinsic. Handles the special sequences for
 /// limited-precision mode.
 void
-SelectionDAGBuilder::visitLog2(CallInst &I) {
+SelectionDAGBuilder::visitLog2(const CallInst &I) {
   SDValue result;
   DebugLoc dl = getCurDebugLoc();
 
@@ -3245,7 +3246,7 @@
 /// visitLog10 - Lower a log10 intrinsic. Handles the special sequences for
 /// limited-precision mode.
 void
-SelectionDAGBuilder::visitLog10(CallInst &I) {
+SelectionDAGBuilder::visitLog10(const CallInst &I) {
   SDValue result;
   DebugLoc dl = getCurDebugLoc();
 
@@ -3347,7 +3348,7 @@
 /// visitExp2 - Lower an exp2 intrinsic. Handles the special sequences for
 /// limited-precision mode.
 void
-SelectionDAGBuilder::visitExp2(CallInst &I) {
+SelectionDAGBuilder::visitExp2(const CallInst &I) {
   SDValue result;
   DebugLoc dl = getCurDebugLoc();
 
@@ -3461,9 +3462,9 @@
 /// visitPow - Lower a pow intrinsic. Handles the special sequences for
 /// limited-precision mode with x == 10.0f.
 void
-SelectionDAGBuilder::visitPow(CallInst &I) {
+SelectionDAGBuilder::visitPow(const CallInst &I) {
   SDValue result;
-  Value *Val = I.getOperand(1);
+  const Value *Val = I.getOperand(1);
   DebugLoc dl = getCurDebugLoc();
   bool IsExp10 = false;
 
@@ -3650,7 +3651,7 @@
 /// we want to emit this as a call to a named external function, return the name
 /// otherwise lower it and return null.
 const char *
-SelectionDAGBuilder::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
+SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   DebugLoc dl = getCurDebugLoc();
   SDValue Res;
 
@@ -3742,17 +3743,17 @@
     if (OptLevel != CodeGenOpt::None)
       // FIXME: Variable debug info is not supported here.
       return 0;
-    DbgDeclareInst &DI = cast<DbgDeclareInst>(I);
+    const DbgDeclareInst &DI = cast<DbgDeclareInst>(I);
     if (!DIDescriptor::ValidDebugInfo(DI.getVariable(), CodeGenOpt::None))
       return 0;
 
     MDNode *Variable = DI.getVariable();
-    Value *Address = DI.getAddress();
+    const Value *Address = DI.getAddress();
     if (!Address)
       return 0;
-    if (BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
+    if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
       Address = BCI->getOperand(0);
-    AllocaInst *AI = dyn_cast<AllocaInst>(Address);
+    const AllocaInst *AI = dyn_cast<AllocaInst>(Address);
     // Don't handle byval struct arguments or VLAs, for example.
     if (!AI)
       return 0;
@@ -3768,13 +3769,13 @@
     return 0;
   }
   case Intrinsic::dbg_value: {
-    DbgValueInst &DI = cast<DbgValueInst>(I);
+    const DbgValueInst &DI = cast<DbgValueInst>(I);
     if (!DIDescriptor::ValidDebugInfo(DI.getVariable(), CodeGenOpt::None))
       return 0;
 
     MDNode *Variable = DI.getVariable();
     uint64_t Offset = DI.getOffset();
-    Value *V = DI.getValue();
+    const Value *V = DI.getValue();
     if (!V)
       return 0;
 
@@ -3800,9 +3801,9 @@
     }
 
     // Build a debug info table entry.
-    if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
+    if (const BitCastInst *BCI = dyn_cast<BitCastInst>(V))
       V = BCI->getOperand(0);
-    AllocaInst *AI = dyn_cast<AllocaInst>(V);
+    const AllocaInst *AI = dyn_cast<AllocaInst>(V);
     // Don't handle byval struct arguments or VLAs, for example.
     if (!AI)
       return 0;
@@ -3922,7 +3923,7 @@
     case Intrinsic::convertuu:  Code = ISD::CVT_UU; break;
     }
     EVT DestVT = TLI.getValueType(I.getType());
-    Value *Op1 = I.getOperand(1);
+    const Value *Op1 = I.getOperand(1);
     Res = DAG.getConvertRndSat(DestVT, getCurDebugLoc(), getValue(Op1),
                                DAG.getValueType(DestVT),
                                DAG.getValueType(getValue(Op1).getValueType()),
@@ -4091,8 +4092,8 @@
   }
   case Intrinsic::gcroot:
     if (GFI) {
-      Value *Alloca = I.getOperand(1);
-      Constant *TypeMap = cast<Constant>(I.getOperand(2));
+      const Value *Alloca = I.getOperand(1);
+      const Constant *TypeMap = cast<Constant>(I.getOperand(2));
 
       FrameIndexSDNode *FI = cast<FrameIndexSDNode>(getValue(Alloca).getNode());
       GFI->addStackRoot(FI->getIndex(), TypeMap);
@@ -4196,7 +4197,7 @@
 ///
 /// This function only tests target-independent requirements.
 static bool
-isInTailCallPosition(CallSite CS, Attributes CalleeRetAttr,
+isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
                      const TargetLowering &TLI) {
   const Instruction *I = CS.getInstruction();
   const BasicBlock *ExitBB = I->getParent();
@@ -4275,7 +4276,7 @@
   return true;
 }
 
-void SelectionDAGBuilder::LowerCallTo(CallSite CS, SDValue Callee,
+void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
                                       bool isTailCall,
                                       MachineBasicBlock *LandingPad) {
   const PointerType *PT = cast<PointerType>(CS.getCalledValue()->getType());
@@ -4323,7 +4324,7 @@
     RetTy = Type::getVoidTy(FTy->getContext());
   }
 
-  for (CallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
+  for (ImmutableCallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
        i != e; ++i) {
     SDValue ArgNode = getValue(*i);
     Entry.Node = ArgNode; Entry.Ty = (*i)->getType();
@@ -4454,12 +4455,12 @@
 
 /// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
 /// value is equal or not-equal to zero.
-static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
-  for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
+static bool IsOnlyUsedInZeroEqualityComparison(const Value *V) {
+  for (Value::const_use_iterator UI = V->use_begin(), E = V->use_end();
        UI != E; ++UI) {
-    if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
+    if (const ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
       if (IC->isEquality())
-        if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
+        if (const Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
           if (C->isNullValue())
             continue;
     // Unknown instruction.
@@ -4468,17 +4469,20 @@
   return true;
 }
 
-static SDValue getMemCmpLoad(Value *PtrVal, MVT LoadVT, const Type *LoadTy,
+static SDValue getMemCmpLoad(const Value *PtrVal, MVT LoadVT,
+                             const Type *LoadTy,
                              SelectionDAGBuilder &Builder) {
 
   // Check to see if this load can be trivially constant folded, e.g. if the
   // input is from a string literal.
-  if (Constant *LoadInput = dyn_cast<Constant>(PtrVal)) {
+  if (const Constant *LoadInput = dyn_cast<Constant>(PtrVal)) {
     // Cast pointer to the type we really want to load.
-    LoadInput = ConstantExpr::getBitCast(LoadInput,
+    LoadInput = ConstantExpr::getBitCast(const_cast<Constant *>(LoadInput),
                                          PointerType::getUnqual(LoadTy));
 
-    if (Constant *LoadCst = ConstantFoldLoadFromConstPtr(LoadInput, Builder.TD))
+    if (const Constant *LoadCst =
+          ConstantFoldLoadFromConstPtr(const_cast<Constant *>(LoadInput),
+                                       Builder.TD))
       return Builder.getValue(LoadCst);
   }
 
@@ -4511,18 +4515,18 @@
 /// visitMemCmpCall - See if we can lower a call to memcmp in an optimized form.
 /// If so, return true and lower it, otherwise return false and it will be
 /// lowered like a normal call.
-bool SelectionDAGBuilder::visitMemCmpCall(CallInst &I) {
+bool SelectionDAGBuilder::visitMemCmpCall(const CallInst &I) {
   // Verify that the prototype makes sense.  int memcmp(void*,void*,size_t)
   if (I.getNumOperands() != 4)
     return false;
 
-  Value *LHS = I.getOperand(1), *RHS = I.getOperand(2);
+  const Value *LHS = I.getOperand(1), *RHS = I.getOperand(2);
   if (!LHS->getType()->isPointerTy() || !RHS->getType()->isPointerTy() ||
       !I.getOperand(3)->getType()->isIntegerTy() ||
       !I.getType()->isIntegerTy())
     return false;
 
-  ConstantInt *Size = dyn_cast<ConstantInt>(I.getOperand(3));
+  const ConstantInt *Size = dyn_cast<ConstantInt>(I.getOperand(3));
 
   // memcmp(S1,S2,2) != 0 -> (*(short*)LHS != *(short*)RHS)  != 0
   // memcmp(S1,S2,4) != 0 -> (*(int*)LHS != *(int*)RHS)  != 0
@@ -4588,7 +4592,7 @@
 }
 
 
-void SelectionDAGBuilder::visitCall(CallInst &I) {
+void SelectionDAGBuilder::visitCall(const CallInst &I) {
   const char *RenameFn = 0;
   if (Function *F = I.getCalledFunction()) {
     if (F->isDeclaration()) {
@@ -5160,8 +5164,8 @@
 
 /// visitInlineAsm - Handle a call to an InlineAsm object.
 ///
-void SelectionDAGBuilder::visitInlineAsm(CallSite CS) {
-  InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
+void SelectionDAGBuilder::visitInlineAsm(ImmutableCallSite CS) {
+  const InlineAsm *IA = cast<InlineAsm>(CS.getCalledValue());
 
   /// ConstraintOperands - Information about all of the constraints.
   std::vector<SDISelAsmOperandInfo> ConstraintOperands;
@@ -5197,7 +5201,7 @@
     case InlineAsm::isOutput:
       // Indirect outputs just consume an argument.
       if (OpInfo.isIndirect) {
-        OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
+        OpInfo.CallOperandVal = const_cast<Value *>(CS.getArgument(ArgNo++));
         break;
       }
 
@@ -5214,7 +5218,7 @@
       ++ResNo;
       break;
     case InlineAsm::isInput:
-      OpInfo.CallOperandVal = CS.getArgument(ArgNo++);
+      OpInfo.CallOperandVal = const_cast<Value *>(CS.getArgument(ArgNo++));
       break;
     case InlineAsm::isClobber:
       // Nothing to do.
@@ -5227,7 +5231,7 @@
       // Strip bitcasts, if any.  This mostly comes up for functions.
       OpInfo.CallOperandVal = OpInfo.CallOperandVal->stripPointerCasts();
 
-      if (BasicBlock *BB = dyn_cast<BasicBlock>(OpInfo.CallOperandVal)) {
+      if (const BasicBlock *BB = dyn_cast<BasicBlock>(OpInfo.CallOperandVal)) {
         OpInfo.CallOperand = DAG.getBasicBlock(FuncInfo.MBBMap[BB]);
       } else {
         OpInfo.CallOperand = getValue(OpInfo.CallOperandVal);
@@ -5280,7 +5284,7 @@
 
       // If the operand is a float, integer, or vector constant, spill to a
       // constant pool entry to get its address.
-      Value *OpVal = OpInfo.CallOperandVal;
+      const Value *OpVal = OpInfo.CallOperandVal;
       if (isa<ConstantFP>(OpVal) || isa<ConstantInt>(OpVal) ||
           isa<ConstantVector>(OpVal)) {
         OpInfo.CallOperand = DAG.getConstantPool(cast<Constant>(OpVal),
@@ -5572,17 +5576,16 @@
       return;
   }
 
-  std::vector<std::pair<SDValue, Value*> > StoresToEmit;
+  std::vector<std::pair<SDValue, const Value *> > StoresToEmit;
 
   // Process indirect outputs, first output all of the flagged copies out of
   // physregs.
   for (unsigned i = 0, e = IndirectStoresToEmit.size(); i != e; ++i) {
     RegsForValue &OutRegs = IndirectStoresToEmit[i].first;
-    Value *Ptr = IndirectStoresToEmit[i].second;
+    const Value *Ptr = IndirectStoresToEmit[i].second;
     SDValue OutVal = OutRegs.getCopyFromRegs(DAG, getCurDebugLoc(),
                                              Chain, &Flag);
     StoresToEmit.push_back(std::make_pair(OutVal, Ptr));
-
   }
 
   // Emit the non-flagged stores from the physregs.
@@ -5603,14 +5606,14 @@
   DAG.setRoot(Chain);
 }
 
-void SelectionDAGBuilder::visitVAStart(CallInst &I) {
+void SelectionDAGBuilder::visitVAStart(const CallInst &I) {
   DAG.setRoot(DAG.getNode(ISD::VASTART, getCurDebugLoc(),
                           MVT::Other, getRoot(),
                           getValue(I.getOperand(1)),
                           DAG.getSrcValue(I.getOperand(1))));
 }
 
-void SelectionDAGBuilder::visitVAArg(VAArgInst &I) {
+void SelectionDAGBuilder::visitVAArg(const VAArgInst &I) {
   SDValue V = DAG.getVAArg(TLI.getValueType(I.getType()), getCurDebugLoc(),
                            getRoot(), getValue(I.getOperand(0)),
                            DAG.getSrcValue(I.getOperand(0)));
@@ -5618,14 +5621,14 @@
   DAG.setRoot(V.getValue(1));
 }
 
-void SelectionDAGBuilder::visitVAEnd(CallInst &I) {
+void SelectionDAGBuilder::visitVAEnd(const CallInst &I) {
   DAG.setRoot(DAG.getNode(ISD::VAEND, getCurDebugLoc(),
                           MVT::Other, getRoot(),
                           getValue(I.getOperand(1)),
                           DAG.getSrcValue(I.getOperand(1))));
 }
 
-void SelectionDAGBuilder::visitVACopy(CallInst &I) {
+void SelectionDAGBuilder::visitVACopy(const CallInst &I) {
   DAG.setRoot(DAG.getNode(ISD::VACOPY, getCurDebugLoc(),
                           MVT::Other, getRoot(),
                           getValue(I.getOperand(1)),
@@ -5807,7 +5810,8 @@
   return SDValue();
 }
 
-void SelectionDAGBuilder::CopyValueToVirtualRegister(Value *V, unsigned Reg) {
+void
+SelectionDAGBuilder::CopyValueToVirtualRegister(const Value *V, unsigned Reg) {
   SDValue Op = getValue(V);
   assert((Op.getOpcode() != ISD::CopyFromReg ||
           cast<RegisterSDNode>(Op.getOperand(1))->getReg() != Reg) &&
@@ -5822,9 +5826,9 @@
 
 #include "llvm/CodeGen/SelectionDAGISel.h"
 
-void SelectionDAGISel::LowerArguments(BasicBlock *LLVMBB) {
+void SelectionDAGISel::LowerArguments(const BasicBlock *LLVMBB) {
   // If this is the entry block, emit arguments.
-  Function &F = *LLVMBB->getParent();
+  const Function &F = *LLVMBB->getParent();
   SelectionDAG &DAG = SDB->DAG;
   SDValue OldRoot = DAG.getRoot();
   DebugLoc dl = SDB->getCurDebugLoc();
@@ -5856,7 +5860,7 @@
 
   // Set up the incoming argument description vector.
   unsigned Idx = 1;
-  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end();
+  for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
        I != E; ++I, ++Idx) {
     SmallVector<EVT, 4> ValueVTs;
     ComputeValueVTs(TLI, I->getType(), ValueVTs);
@@ -5958,7 +5962,7 @@
     ++i;
   }
 
-  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E;
+  for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E;
       ++I, ++Idx) {
     SmallVector<SDValue, 4> ArgValues;
     SmallVector<EVT, 4> ValueVTs;
@@ -6012,15 +6016,15 @@
 /// the end.
 ///
 void
-SelectionDAGISel::HandlePHINodesInSuccessorBlocks(BasicBlock *LLVMBB) {
-  TerminatorInst *TI = LLVMBB->getTerminator();
+SelectionDAGISel::HandlePHINodesInSuccessorBlocks(const BasicBlock *LLVMBB) {
+  const TerminatorInst *TI = LLVMBB->getTerminator();
 
   SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
 
   // Check successor nodes' PHI nodes that expect a constant to be available
   // from this block.
   for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
-    BasicBlock *SuccBB = TI->getSuccessor(succ);
+    const BasicBlock *SuccBB = TI->getSuccessor(succ);
     if (!isa<PHINode>(SuccBB->begin())) continue;
     MachineBasicBlock *SuccMBB = FuncInfo->MBBMap[SuccBB];
 
@@ -6029,20 +6033,19 @@
     if (!SuccsHandled.insert(SuccMBB)) continue;
 
     MachineBasicBlock::iterator MBBI = SuccMBB->begin();
-    PHINode *PN;
 
     // At this point we know that there is a 1-1 correspondence between LLVM PHI
     // nodes and Machine PHI nodes, but the incoming operands have not been
     // emitted yet.
-    for (BasicBlock::iterator I = SuccBB->begin();
-         (PN = dyn_cast<PHINode>(I)); ++I) {
+    for (BasicBlock::const_iterator I = SuccBB->begin();
+         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
       // Ignore dead phi's.
       if (PN->use_empty()) continue;
 
       unsigned Reg;
-      Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
+      const Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
 
-      if (Constant *C = dyn_cast<Constant>(PHIOp)) {
+      if (const Constant *C = dyn_cast<Constant>(PHIOp)) {
         unsigned &RegOut = SDB->ConstantsOut[C];
         if (RegOut == 0) {
           RegOut = FuncInfo->CreateRegForValue(C);
@@ -6081,9 +6084,9 @@
 /// creating SelectionDAG nodes.
 ///
 bool
-SelectionDAGISel::HandlePHINodesInSuccessorBlocksFast(BasicBlock *LLVMBB,
+SelectionDAGISel::HandlePHINodesInSuccessorBlocksFast(const BasicBlock *LLVMBB,
                                                       FastISel *F) {
-  TerminatorInst *TI = LLVMBB->getTerminator();
+  const TerminatorInst *TI = LLVMBB->getTerminator();
 
   SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
   unsigned OrigNumPHINodesToUpdate = SDB->PHINodesToUpdate.size();
@@ -6091,7 +6094,7 @@
   // Check successor nodes' PHI nodes that expect a constant to be available
   // from this block.
   for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
-    BasicBlock *SuccBB = TI->getSuccessor(succ);
+    const BasicBlock *SuccBB = TI->getSuccessor(succ);
     if (!isa<PHINode>(SuccBB->begin())) continue;
     MachineBasicBlock *SuccMBB = FuncInfo->MBBMap[SuccBB];
 
@@ -6100,13 +6103,12 @@
     if (!SuccsHandled.insert(SuccMBB)) continue;
 
     MachineBasicBlock::iterator MBBI = SuccMBB->begin();
-    PHINode *PN;
 
     // At this point we know that there is a 1-1 correspondence between LLVM PHI
     // nodes and Machine PHI nodes, but the incoming operands have not been
     // emitted yet.
-    for (BasicBlock::iterator I = SuccBB->begin();
-         (PN = dyn_cast<PHINode>(I)); ++I) {
+    for (BasicBlock::const_iterator I = SuccBB->begin();
+         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
       // Ignore dead phi's.
       if (PN->use_empty()) continue;
 
@@ -6127,7 +6129,7 @@
         }
       }
 
-      Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
+      const Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
 
       unsigned Reg = F->getRegForValue(PHIOp);
       if (Reg == 0) {
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index e38c33c..454a87e 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -142,15 +142,16 @@
   /// CaseRec - A struct with ctor used in lowering switches to a binary tree
   /// of conditional branches.
   struct CaseRec {
-    CaseRec(MachineBasicBlock *bb, Constant *lt, Constant *ge, CaseRange r) :
+    CaseRec(MachineBasicBlock *bb, const Constant *lt, const Constant *ge,
+            CaseRange r) :
     CaseBB(bb), LT(lt), GE(ge), Range(r) {}
 
     /// CaseBB - The MBB in which to emit the compare and branch
     MachineBasicBlock *CaseBB;
     /// LT, GE - If nonzero, we know the current case value must be less-than or
     /// greater-than-or-equal-to these Constants.
-    Constant *LT;
-    Constant *GE;
+    const Constant *LT;
+    const Constant *GE;
     /// Range - A pair of iterators representing the range of case values to be
     /// processed at this point in the binary search tree.
     CaseRange Range;
@@ -181,7 +182,8 @@
   /// SelectionDAGBuilder and SDISel for the code generation of additional basic
   /// blocks needed by multi-case switch statements.
   struct CaseBlock {
-    CaseBlock(ISD::CondCode cc, Value *cmplhs, Value *cmprhs, Value *cmpmiddle,
+    CaseBlock(ISD::CondCode cc, const Value *cmplhs, const Value *cmprhs,
+              const Value *cmpmiddle,
               MachineBasicBlock *truebb, MachineBasicBlock *falsebb,
               MachineBasicBlock *me)
       : CC(cc), CmpLHS(cmplhs), CmpMHS(cmpmiddle), CmpRHS(cmprhs),
@@ -191,7 +193,7 @@
     // CmpLHS/CmpRHS/CmpMHS - The LHS/MHS/RHS of the comparison to emit.
     // Emit by default LHS op RHS. MHS is used for range comparisons:
     // If MHS is not null: (LHS <= MHS) and (MHS <= RHS).
-    Value *CmpLHS, *CmpMHS, *CmpRHS;
+    const Value *CmpLHS, *CmpMHS, *CmpRHS;
     // TrueBB/FalseBB - the block to branch to if the setcc is true/false.
     MachineBasicBlock *TrueBB, *FalseBB;
     // ThisBB - the block into which to emit the code for the setcc and branches
@@ -213,12 +215,12 @@
     MachineBasicBlock *Default;
   };
   struct JumpTableHeader {
-    JumpTableHeader(APInt F, APInt L, Value *SV, MachineBasicBlock *H,
+    JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
                     bool E = false):
       First(F), Last(L), SValue(SV), HeaderBB(H), Emitted(E) {}
     APInt First;
     APInt Last;
-    Value *SValue;
+    const Value *SValue;
     MachineBasicBlock *HeaderBB;
     bool Emitted;
   };
@@ -235,7 +237,7 @@
   typedef SmallVector<BitTestCase, 3> BitTestInfo;
 
   struct BitTestBlock {
-    BitTestBlock(APInt F, APInt R, Value* SV,
+    BitTestBlock(APInt F, APInt R, const Value* SV,
                  unsigned Rg, bool E,
                  MachineBasicBlock* P, MachineBasicBlock* D,
                  const BitTestInfo& C):
@@ -243,7 +245,7 @@
       Parent(P), Default(D), Cases(C) { }
     APInt First;
     APInt Range;
-    Value  *SValue;
+    const Value *SValue;
     unsigned Reg;
     bool Emitted;
     MachineBasicBlock *Parent;
@@ -280,7 +282,7 @@
 
   // Emit PHI-node-operand constants only once even if used by multiple
   // PHI nodes.
-  DenseMap<Constant*, unsigned> ConstantsOut;
+  DenseMap<const Constant *, unsigned> ConstantsOut;
 
   /// FuncInfo - Information about the function as a whole.
   ///
@@ -336,16 +338,16 @@
 
   unsigned getSDNodeOrder() const { return SDNodeOrder; }
 
-  void CopyValueToVirtualRegister(Value *V, unsigned Reg);
+  void CopyValueToVirtualRegister(const Value *V, unsigned Reg);
 
   /// AssignOrderingToNode - Assign an ordering to the node. The order is gotten
   /// from how the code appeared in the source. The ordering is used by the
   /// scheduler to effectively turn off scheduling.
   void AssignOrderingToNode(const SDNode *Node);
 
-  void visit(Instruction &I);
+  void visit(const Instruction &I);
 
-  void visit(unsigned Opcode, User &I);
+  void visit(unsigned Opcode, const User &I);
 
   void setCurrentBasicBlock(MachineBasicBlock *MBB) { CurMBB = MBB; }
 
@@ -361,43 +363,43 @@
                             std::set<unsigned> &OutputRegs, 
                             std::set<unsigned> &InputRegs);
 
-  void FindMergedConditions(Value *Cond, MachineBasicBlock *TBB,
+  void FindMergedConditions(const Value *Cond, MachineBasicBlock *TBB,
                             MachineBasicBlock *FBB, MachineBasicBlock *CurBB,
                             unsigned Opc);
-  void EmitBranchForMergedCondition(Value *Cond, MachineBasicBlock *TBB,
+  void EmitBranchForMergedCondition(const Value *Cond, MachineBasicBlock *TBB,
                                     MachineBasicBlock *FBB,
                                     MachineBasicBlock *CurBB);
   bool ShouldEmitAsBranches(const std::vector<CaseBlock> &Cases);
-  bool isExportableFromCurrentBlock(Value *V, const BasicBlock *FromBB);
-  void CopyToExportRegsIfNeeded(Value *V);
-  void ExportFromCurrentBlock(Value *V);
-  void LowerCallTo(CallSite CS, SDValue Callee, bool IsTailCall,
+  bool isExportableFromCurrentBlock(const Value *V, const BasicBlock *FromBB);
+  void CopyToExportRegsIfNeeded(const Value *V);
+  void ExportFromCurrentBlock(const Value *V);
+  void LowerCallTo(ImmutableCallSite CS, SDValue Callee, bool IsTailCall,
                    MachineBasicBlock *LandingPad = NULL);
 
 private:
   // Terminator instructions.
-  void visitRet(ReturnInst &I);
-  void visitBr(BranchInst &I);
-  void visitSwitch(SwitchInst &I);
-  void visitIndirectBr(IndirectBrInst &I);
-  void visitUnreachable(UnreachableInst &I) { /* noop */ }
+  void visitRet(const ReturnInst &I);
+  void visitBr(const BranchInst &I);
+  void visitSwitch(const SwitchInst &I);
+  void visitIndirectBr(const IndirectBrInst &I);
+  void visitUnreachable(const UnreachableInst &I) { /* noop */ }
 
   // Helpers for visitSwitch
   bool handleSmallSwitchRange(CaseRec& CR,
                               CaseRecVector& WorkList,
-                              Value* SV,
+                              const Value* SV,
                               MachineBasicBlock* Default);
   bool handleJTSwitchCase(CaseRec& CR,
                           CaseRecVector& WorkList,
-                          Value* SV,
+                          const Value* SV,
                           MachineBasicBlock* Default);
   bool handleBTSplitSwitchCase(CaseRec& CR,
                                CaseRecVector& WorkList,
-                               Value* SV,
+                               const Value* SV,
                                MachineBasicBlock* Default);
   bool handleBitTestsSwitchCase(CaseRec& CR,
                                 CaseRecVector& WorkList,
-                                Value* SV,
+                                const Value* SV,
                                 MachineBasicBlock* Default);  
 public:
   void visitSwitchCase(CaseBlock &CB);
@@ -410,87 +412,87 @@
   
 private:
   // These all get lowered before this pass.
-  void visitInvoke(InvokeInst &I);
-  void visitUnwind(UnwindInst &I);
+  void visitInvoke(const InvokeInst &I);
+  void visitUnwind(const UnwindInst &I);
 
-  void visitBinary(User &I, unsigned OpCode);
-  void visitShift(User &I, unsigned Opcode);
-  void visitAdd(User &I)  { visitBinary(I, ISD::ADD); }
-  void visitFAdd(User &I) { visitBinary(I, ISD::FADD); }
-  void visitSub(User &I)  { visitBinary(I, ISD::SUB); }
-  void visitFSub(User &I);
-  void visitMul(User &I)  { visitBinary(I, ISD::MUL); }
-  void visitFMul(User &I) { visitBinary(I, ISD::FMUL); }
-  void visitURem(User &I) { visitBinary(I, ISD::UREM); }
-  void visitSRem(User &I) { visitBinary(I, ISD::SREM); }
-  void visitFRem(User &I) { visitBinary(I, ISD::FREM); }
-  void visitUDiv(User &I) { visitBinary(I, ISD::UDIV); }
-  void visitSDiv(User &I) { visitBinary(I, ISD::SDIV); }
-  void visitFDiv(User &I) { visitBinary(I, ISD::FDIV); }
-  void visitAnd (User &I) { visitBinary(I, ISD::AND); }
-  void visitOr  (User &I) { visitBinary(I, ISD::OR); }
-  void visitXor (User &I) { visitBinary(I, ISD::XOR); }
-  void visitShl (User &I) { visitShift(I, ISD::SHL); }
-  void visitLShr(User &I) { visitShift(I, ISD::SRL); }
-  void visitAShr(User &I) { visitShift(I, ISD::SRA); }
-  void visitICmp(User &I);
-  void visitFCmp(User &I);
+  void visitBinary(const User &I, unsigned OpCode);
+  void visitShift(const User &I, unsigned Opcode);
+  void visitAdd(const User &I)  { visitBinary(I, ISD::ADD); }
+  void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
+  void visitSub(const User &I)  { visitBinary(I, ISD::SUB); }
+  void visitFSub(const User &I);
+  void visitMul(const User &I)  { visitBinary(I, ISD::MUL); }
+  void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
+  void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
+  void visitSRem(const User &I) { visitBinary(I, ISD::SREM); }
+  void visitFRem(const User &I) { visitBinary(I, ISD::FREM); }
+  void visitUDiv(const User &I) { visitBinary(I, ISD::UDIV); }
+  void visitSDiv(const User &I) { visitBinary(I, ISD::SDIV); }
+  void visitFDiv(const User &I) { visitBinary(I, ISD::FDIV); }
+  void visitAnd (const User &I) { visitBinary(I, ISD::AND); }
+  void visitOr  (const User &I) { visitBinary(I, ISD::OR); }
+  void visitXor (const User &I) { visitBinary(I, ISD::XOR); }
+  void visitShl (const User &I) { visitShift(I, ISD::SHL); }
+  void visitLShr(const User &I) { visitShift(I, ISD::SRL); }
+  void visitAShr(const User &I) { visitShift(I, ISD::SRA); }
+  void visitICmp(const User &I);
+  void visitFCmp(const User &I);
   // Visit the conversion instructions
-  void visitTrunc(User &I);
-  void visitZExt(User &I);
-  void visitSExt(User &I);
-  void visitFPTrunc(User &I);
-  void visitFPExt(User &I);
-  void visitFPToUI(User &I);
-  void visitFPToSI(User &I);
-  void visitUIToFP(User &I);
-  void visitSIToFP(User &I);
-  void visitPtrToInt(User &I);
-  void visitIntToPtr(User &I);
-  void visitBitCast(User &I);
+  void visitTrunc(const User &I);
+  void visitZExt(const User &I);
+  void visitSExt(const User &I);
+  void visitFPTrunc(const User &I);
+  void visitFPExt(const User &I);
+  void visitFPToUI(const User &I);
+  void visitFPToSI(const User &I);
+  void visitUIToFP(const User &I);
+  void visitSIToFP(const User &I);
+  void visitPtrToInt(const User &I);
+  void visitIntToPtr(const User &I);
+  void visitBitCast(const User &I);
 
-  void visitExtractElement(User &I);
-  void visitInsertElement(User &I);
-  void visitShuffleVector(User &I);
+  void visitExtractElement(const User &I);
+  void visitInsertElement(const User &I);
+  void visitShuffleVector(const User &I);
 
-  void visitExtractValue(ExtractValueInst &I);
-  void visitInsertValue(InsertValueInst &I);
+  void visitExtractValue(const ExtractValueInst &I);
+  void visitInsertValue(const InsertValueInst &I);
 
-  void visitGetElementPtr(User &I);
-  void visitSelect(User &I);
+  void visitGetElementPtr(const User &I);
+  void visitSelect(const User &I);
 
-  void visitAlloca(AllocaInst &I);
-  void visitLoad(LoadInst &I);
-  void visitStore(StoreInst &I);
-  void visitPHI(PHINode &I) { } // PHI nodes are handled specially.
-  void visitCall(CallInst &I);
-  bool visitMemCmpCall(CallInst &I);
+  void visitAlloca(const AllocaInst &I);
+  void visitLoad(const LoadInst &I);
+  void visitStore(const StoreInst &I);
+  void visitPHI(const PHINode &I) { } // PHI nodes are handled specially.
+  void visitCall(const CallInst &I);
+  bool visitMemCmpCall(const CallInst &I);
   
-  void visitInlineAsm(CallSite CS);
-  const char *visitIntrinsicCall(CallInst &I, unsigned Intrinsic);
-  void visitTargetIntrinsic(CallInst &I, unsigned Intrinsic);
+  void visitInlineAsm(ImmutableCallSite CS);
+  const char *visitIntrinsicCall(const CallInst &I, unsigned Intrinsic);
+  void visitTargetIntrinsic(const CallInst &I, unsigned Intrinsic);
 
-  void visitPow(CallInst &I);
-  void visitExp2(CallInst &I);
-  void visitExp(CallInst &I);
-  void visitLog(CallInst &I);
-  void visitLog2(CallInst &I);
-  void visitLog10(CallInst &I);
+  void visitPow(const CallInst &I);
+  void visitExp2(const CallInst &I);
+  void visitExp(const CallInst &I);
+  void visitLog(const CallInst &I);
+  void visitLog2(const CallInst &I);
+  void visitLog10(const CallInst &I);
 
-  void visitVAStart(CallInst &I);
-  void visitVAArg(VAArgInst &I);
-  void visitVAEnd(CallInst &I);
-  void visitVACopy(CallInst &I);
+  void visitVAStart(const CallInst &I);
+  void visitVAArg(const VAArgInst &I);
+  void visitVAEnd(const CallInst &I);
+  void visitVACopy(const CallInst &I);
 
-  void visitUserOp1(Instruction &I) {
+  void visitUserOp1(const Instruction &I) {
     llvm_unreachable("UserOp1 should not exist at instruction selection time!");
   }
-  void visitUserOp2(Instruction &I) {
+  void visitUserOp2(const Instruction &I) {
     llvm_unreachable("UserOp2 should not exist at instruction selection time!");
   }
   
-  const char *implVisitBinaryAtomic(CallInst& I, ISD::NodeType Op);
-  const char *implVisitAluOverflow(CallInst &I, ISD::NodeType Op);
+  const char *implVisitBinaryAtomic(const CallInst& I, ISD::NodeType Op);
+  const char *implVisitAluOverflow(const CallInst &I, ISD::NodeType Op);
 };
 
 } // end namespace llvm
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index b6a56b6..7618166 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -226,7 +226,7 @@
 
 /// SetDebugLoc - Update MF's and SDB's DebugLocs if debug information is
 /// attached with this instruction.
-static void SetDebugLoc(Instruction *I, SelectionDAGBuilder *SDB,
+static void SetDebugLoc(const Instruction *I, SelectionDAGBuilder *SDB,
                         FastISel *FastIS, MachineFunction *MF) {
   DebugLoc DL = I->getDebugLoc();
   if (DL.isUnknown()) return;
@@ -249,15 +249,16 @@
     FastIS->setCurDebugLoc(DebugLoc());
 }
 
-void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB,
-                                        BasicBlock::iterator Begin,
-                                        BasicBlock::iterator End,
+void SelectionDAGISel::SelectBasicBlock(const BasicBlock *LLVMBB,
+                                        BasicBlock::const_iterator Begin,
+                                        BasicBlock::const_iterator End,
                                         bool &HadTailCall) {
   SDB->setCurrentBasicBlock(BB);
 
   // Lower all of the non-terminator instructions. If a call is emitted
   // as a tail call, cease emitting nodes for this block.
-  for (BasicBlock::iterator I = Begin; I != End && !SDB->HasTailCall; ++I) {
+  for (BasicBlock::const_iterator I = Begin;
+       I != End && !SDB->HasTailCall; ++I) {
     SetDebugLoc(I, SDB, 0, MF);
 
     // Visit the instruction. Terminators are handled below.
@@ -270,7 +271,7 @@
   if (!SDB->HasTailCall) {
     // Ensure that all instructions which are used outside of their defining
     // blocks are available as virtual registers.  Invoke is handled elsewhere.
-    for (BasicBlock::iterator I = Begin; I != End; ++I)
+    for (BasicBlock::const_iterator I = Begin; I != End; ++I)
       if (!isa<PHINode>(I) && !isa<InvokeInst>(I))
         SDB->CopyToExportRegsIfNeeded(I);
 
@@ -744,7 +745,7 @@
   }
 }
 
-void SelectionDAGISel::SelectAllBasicBlocks(Function &Fn) {
+void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
   // Initialize the Fast-ISel state, if needed.
   FastISel *FastIS = 0;
   if (EnableFastISel)
@@ -756,13 +757,13 @@
                                 );
 
   // Iterate over all basic blocks in the function.
-  for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
-    BasicBlock *LLVMBB = &*I;
+  for (Function::const_iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
+    const BasicBlock *LLVMBB = &*I;
     BB = FuncInfo->MBBMap[LLVMBB];
 
-    BasicBlock::iterator const Begin = LLVMBB->begin();
-    BasicBlock::iterator const End = LLVMBB->end();
-    BasicBlock::iterator BI = Begin;
+    BasicBlock::const_iterator const Begin = LLVMBB->begin();
+    BasicBlock::const_iterator const End = LLVMBB->end();
+    BasicBlock::const_iterator BI = Begin;
 
     // Lower any arguments needed in this block if this is the entry block.
     bool SuppressFastISel = false;
@@ -773,7 +774,7 @@
       // fast-isel in the entry block.
       if (FastIS) {
         unsigned j = 1;
-        for (Function::arg_iterator I = Fn.arg_begin(), E = Fn.arg_end();
+        for (Function::const_arg_iterator I = Fn.arg_begin(), E = Fn.arg_end();
              I != E; ++I, ++j)
           if (Fn.paramHasAttr(j, Attribute::ByVal)) {
             if (EnableFastISelVerbose || EnableFastISelAbort)
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index ea2ff2f..df923c6 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -2245,7 +2245,7 @@
 
 /// isGAPlusOffset - Returns true (and the GlobalValue and the offset) if the
 /// node is a GlobalAddress + offset.
-bool TargetLowering::isGAPlusOffset(SDNode *N, GlobalValue* &GA,
+bool TargetLowering::isGAPlusOffset(SDNode *N, const GlobalValue* &GA,
                                     int64_t &Offset) const {
   if (isa<GlobalAddressSDNode>(N)) {
     GlobalAddressSDNode *GASD = cast<GlobalAddressSDNode>(N);