diff --git a/ast.cpp b/ast.cpp
index 064226b4..5e71b9b6 100644
--- a/ast.cpp
+++ b/ast.cpp
@@ -86,7 +86,7 @@ AST::GenerateIR() {
 
 ASTNode *
 WalkAST(ASTNode *node, ASTPreCallBackFunc preFunc, ASTPostCallBackFunc postFunc,
-        void *data) {
+        void *data, ASTPostCallBackFunc preUpdate) {
     if (node == NULL)
         return node;
 
@@ -97,6 +97,10 @@ WalkAST(ASTNode *node, ASTPreCallBackFunc preFunc, ASTPostCallBackFunc postFunc,
             return node;
     }
 
+    if (preUpdate != NULL) {
+        node = preUpdate(node, data);
+    }
+
     ////////////////////////////////////////////////////////////////////////////
     // Handle Statements
     if (llvm::dyn_cast<Stmt>(node) != NULL) {
@@ -120,54 +124,54 @@ WalkAST(ASTNode *node, ASTPreCallBackFunc preFunc, ASTPostCallBackFunc postFunc,
         UnmaskedStmt *ums;
 
         if ((es = llvm::dyn_cast<ExprStmt>(node)) != NULL)
-            es->expr = (Expr *)WalkAST(es->expr, preFunc, postFunc, data);
+            es->expr = (Expr *)WalkAST(es->expr, preFunc, postFunc, data, preUpdate);
         else if ((ds = llvm::dyn_cast<DeclStmt>(node)) != NULL) {
             for (unsigned int i = 0; i < ds->vars.size(); ++i)
                 ds->vars[i].init = (Expr *)WalkAST(ds->vars[i].init, preFunc,
-                                                   postFunc, data);
+                                                   postFunc, data, preUpdate);
         }
         else if ((is = llvm::dyn_cast<IfStmt>(node)) != NULL) {
-            is->test = (Expr *)WalkAST(is->test, preFunc, postFunc, data);
+            is->test = (Expr *)WalkAST(is->test, preFunc, postFunc, data, preUpdate);
             is->trueStmts = (Stmt *)WalkAST(is->trueStmts, preFunc,
-                                            postFunc, data);
+                                            postFunc, data, preUpdate);
             is->falseStmts = (Stmt *)WalkAST(is->falseStmts, preFunc,
-                                             postFunc, data);
+                                             postFunc, data, preUpdate);
         }
         else if ((dos = llvm::dyn_cast<DoStmt>(node)) != NULL) {
             dos->testExpr = (Expr *)WalkAST(dos->testExpr, preFunc,
-                                            postFunc, data);
+                                            postFunc, data, preUpdate);
             dos->bodyStmts = (Stmt *)WalkAST(dos->bodyStmts, preFunc,
-                                             postFunc, data);
+                                             postFunc, data, preUpdate);
         }
         else if ((fs = llvm::dyn_cast<ForStmt>(node)) != NULL) {
-            fs->init = (Stmt *)WalkAST(fs->init, preFunc, postFunc, data);
-            fs->test = (Expr *)WalkAST(fs->test, preFunc, postFunc, data);
-            fs->step = (Stmt *)WalkAST(fs->step, preFunc, postFunc, data);
-            fs->stmts = (Stmt *)WalkAST(fs->stmts, preFunc, postFunc, data);
+            fs->init = (Stmt *)WalkAST(fs->init, preFunc, postFunc, data, preUpdate);
+            fs->test = (Expr *)WalkAST(fs->test, preFunc, postFunc, data, preUpdate);
+            fs->step = (Stmt *)WalkAST(fs->step, preFunc, postFunc, data, preUpdate);
+            fs->stmts = (Stmt *)WalkAST(fs->stmts, preFunc, postFunc, data, preUpdate);
         }
         else if ((fes = llvm::dyn_cast<ForeachStmt>(node)) != NULL) {
             for (unsigned int i = 0; i < fes->startExprs.size(); ++i)
                 fes->startExprs[i] = (Expr *)WalkAST(fes->startExprs[i], preFunc,
-                                                     postFunc, data);
+                                                     postFunc, data, preUpdate);
             for (unsigned int i = 0; i < fes->endExprs.size(); ++i)
                 fes->endExprs[i] = (Expr *)WalkAST(fes->endExprs[i], preFunc,
-                                                   postFunc, data);
-            fes->stmts = (Stmt *)WalkAST(fes->stmts, preFunc, postFunc, data);
+                                                   postFunc, data, preUpdate);
+            fes->stmts = (Stmt *)WalkAST(fes->stmts, preFunc, postFunc, data, preUpdate);
         }
         else if ((fas = llvm::dyn_cast<ForeachActiveStmt>(node)) != NULL) {
-            fas->stmts = (Stmt *)WalkAST(fas->stmts, preFunc, postFunc, data);
+            fas->stmts = (Stmt *)WalkAST(fas->stmts, preFunc, postFunc, data, preUpdate);
         }
         else if ((fus = llvm::dyn_cast<ForeachUniqueStmt>(node)) != NULL) {
-            fus->expr = (Expr *)WalkAST(fus->expr, preFunc, postFunc, data);
-            fus->stmts = (Stmt *)WalkAST(fus->stmts, preFunc, postFunc, data);
+            fus->expr = (Expr *)WalkAST(fus->expr, preFunc, postFunc, data, preUpdate);
+            fus->stmts = (Stmt *)WalkAST(fus->stmts, preFunc, postFunc, data, preUpdate);
         }
         else if ((cs = llvm::dyn_cast<CaseStmt>(node)) != NULL)
-            cs->stmts = (Stmt *)WalkAST(cs->stmts, preFunc, postFunc, data);
+            cs->stmts = (Stmt *)WalkAST(cs->stmts, preFunc, postFunc, data, preUpdate);
         else if ((defs = llvm::dyn_cast<DefaultStmt>(node)) != NULL)
-            defs->stmts = (Stmt *)WalkAST(defs->stmts, preFunc, postFunc, data);
+            defs->stmts = (Stmt *)WalkAST(defs->stmts, preFunc, postFunc, data, preUpdate);
         else if ((ss = llvm::dyn_cast<SwitchStmt>(node)) != NULL) {
-            ss->expr = (Expr *)WalkAST(ss->expr, preFunc, postFunc, data);
-            ss->stmts = (Stmt *)WalkAST(ss->stmts, preFunc, postFunc, data);
+            ss->expr = (Expr *)WalkAST(ss->expr, preFunc, postFunc, data, preUpdate);
+            ss->stmts = (Stmt *)WalkAST(ss->stmts, preFunc, postFunc, data, preUpdate);
         }
         else if (llvm::dyn_cast<BreakStmt>(node) != NULL ||
                  llvm::dyn_cast<ContinueStmt>(node) != NULL ||
@@ -175,22 +179,22 @@ WalkAST(ASTNode *node, ASTPreCallBackFunc preFunc, ASTPostCallBackFunc postFunc,
             // nothing
         }
         else if ((ls = llvm::dyn_cast<LabeledStmt>(node)) != NULL)
-            ls->stmt = (Stmt *)WalkAST(ls->stmt, preFunc, postFunc, data);
+            ls->stmt = (Stmt *)WalkAST(ls->stmt, preFunc, postFunc, data, preUpdate);
         else if ((rs = llvm::dyn_cast<ReturnStmt>(node)) != NULL)
-            rs->expr = (Expr *)WalkAST(rs->expr, preFunc, postFunc, data);
+            rs->expr = (Expr *)WalkAST(rs->expr, preFunc, postFunc, data, preUpdate);
         else if ((sl = llvm::dyn_cast<StmtList>(node)) != NULL) {
             std::vector<Stmt *> &sls = sl->stmts;
             for (unsigned int i = 0; i < sls.size(); ++i)
-                sls[i] = (Stmt *)WalkAST(sls[i], preFunc, postFunc, data);
+                sls[i] = (Stmt *)WalkAST(sls[i], preFunc, postFunc, data, preUpdate);
         }
         else if ((ps = llvm::dyn_cast<PrintStmt>(node)) != NULL)
-            ps->values = (Expr *)WalkAST(ps->values, preFunc, postFunc, data);
+            ps->values = (Expr *)WalkAST(ps->values, preFunc, postFunc, data, preUpdate);
         else if ((as = llvm::dyn_cast<AssertStmt>(node)) != NULL)
-            as->expr = (Expr *)WalkAST(as->expr, preFunc, postFunc, data);
+            as->expr = (Expr *)WalkAST(as->expr, preFunc, postFunc, data, preUpdate);
         else if ((dels = llvm::dyn_cast<DeleteStmt>(node)) != NULL)
-            dels->expr = (Expr *)WalkAST(dels->expr, preFunc, postFunc, data);
+            dels->expr = (Expr *)WalkAST(dels->expr, preFunc, postFunc, data, preUpdate);
         else if ((ums = llvm::dyn_cast<UnmaskedStmt>(node)) != NULL)
-            ums->stmts = (Stmt *)WalkAST(ums->stmts, preFunc, postFunc, data);
+            ums->stmts = (Stmt *)WalkAST(ums->stmts, preFunc, postFunc, data, preUpdate);
         else
             FATAL("Unhandled statement type in WalkAST()");
     }
@@ -215,57 +219,57 @@ WalkAST(ASTNode *node, ASTPreCallBackFunc preFunc, ASTPostCallBackFunc postFunc,
         NewExpr *newe;
 
         if ((ue = llvm::dyn_cast<UnaryExpr>(node)) != NULL)
-            ue->expr = (Expr *)WalkAST(ue->expr, preFunc, postFunc, data);
+            ue->expr = (Expr *)WalkAST(ue->expr, preFunc, postFunc, data, preUpdate);
         else if ((be = llvm::dyn_cast<BinaryExpr>(node)) != NULL) {
-            be->arg0 = (Expr *)WalkAST(be->arg0, preFunc, postFunc, data);
-            be->arg1 = (Expr *)WalkAST(be->arg1, preFunc, postFunc, data);
+            be->arg0 = (Expr *)WalkAST(be->arg0, preFunc, postFunc, data, preUpdate);
+            be->arg1 = (Expr *)WalkAST(be->arg1, preFunc, postFunc, data, preUpdate);
         }
         else if ((ae = llvm::dyn_cast<AssignExpr>(node)) != NULL) {
-            ae->lvalue = (Expr *)WalkAST(ae->lvalue, preFunc, postFunc, data);
-            ae->rvalue = (Expr *)WalkAST(ae->rvalue, preFunc, postFunc, data);
+            ae->lvalue = (Expr *)WalkAST(ae->lvalue, preFunc, postFunc, data, preUpdate);
+            ae->rvalue = (Expr *)WalkAST(ae->rvalue, preFunc, postFunc, data, preUpdate);
         }
         else if ((se = llvm::dyn_cast<SelectExpr>(node)) != NULL) {
-            se->test = (Expr *)WalkAST(se->test, preFunc, postFunc, data);
-            se->expr1 = (Expr *)WalkAST(se->expr1, preFunc, postFunc, data);
-            se->expr2 = (Expr *)WalkAST(se->expr2, preFunc, postFunc, data);
+            se->test = (Expr *)WalkAST(se->test, preFunc, postFunc, data, preUpdate);
+            se->expr1 = (Expr *)WalkAST(se->expr1, preFunc, postFunc, data, preUpdate);
+            se->expr2 = (Expr *)WalkAST(se->expr2, preFunc, postFunc, data, preUpdate);
         }
         else if ((el = llvm::dyn_cast<ExprList>(node)) != NULL) {
             for (unsigned int i = 0; i < el->exprs.size(); ++i)
                 el->exprs[i] = (Expr *)WalkAST(el->exprs[i], preFunc,
-                                               postFunc, data);
+                                               postFunc, data, preUpdate);
         }
         else if ((fce = llvm::dyn_cast<FunctionCallExpr>(node)) != NULL) {
-            fce->func = (Expr *)WalkAST(fce->func, preFunc, postFunc, data);
-            fce->args = (ExprList *)WalkAST(fce->args, preFunc, postFunc, data);
+            fce->func = (Expr *)WalkAST(fce->func, preFunc, postFunc, data, preUpdate);
+            fce->args = (ExprList *)WalkAST(fce->args, preFunc, postFunc, data, preUpdate);
             for (int k = 0; k < 3; k++)
               fce->launchCountExpr[0] = (Expr *)WalkAST(fce->launchCountExpr[0], preFunc,
-                                                   postFunc, data);
+                                                   postFunc, data, preUpdate);
         }
         else if ((ie = llvm::dyn_cast<IndexExpr>(node)) != NULL) {
-            ie->baseExpr = (Expr *)WalkAST(ie->baseExpr, preFunc, postFunc, data);
-            ie->index = (Expr *)WalkAST(ie->index, preFunc, postFunc, data);
+            ie->baseExpr = (Expr *)WalkAST(ie->baseExpr, preFunc, postFunc, data, preUpdate);
+            ie->index = (Expr *)WalkAST(ie->index, preFunc, postFunc, data, preUpdate);
         }
         else if ((me = llvm::dyn_cast<MemberExpr>(node)) != NULL)
-            me->expr = (Expr *)WalkAST(me->expr, preFunc, postFunc, data);
+            me->expr = (Expr *)WalkAST(me->expr, preFunc, postFunc, data, preUpdate);
         else if ((tce = llvm::dyn_cast<TypeCastExpr>(node)) != NULL)
-            tce->expr = (Expr *)WalkAST(tce->expr, preFunc, postFunc, data);
+            tce->expr = (Expr *)WalkAST(tce->expr, preFunc, postFunc, data, preUpdate);
         else if ((re = llvm::dyn_cast<ReferenceExpr>(node)) != NULL)
-            re->expr = (Expr *)WalkAST(re->expr, preFunc, postFunc, data);
+            re->expr = (Expr *)WalkAST(re->expr, preFunc, postFunc, data, preUpdate);
         else if ((ptrderef = llvm::dyn_cast<PtrDerefExpr>(node)) != NULL)
             ptrderef->expr = (Expr *)WalkAST(ptrderef->expr, preFunc, postFunc,
-                                             data);
+                                             data, preUpdate);
         else if ((refderef = llvm::dyn_cast<RefDerefExpr>(node)) != NULL)
             refderef->expr = (Expr *)WalkAST(refderef->expr, preFunc, postFunc,
-                                             data);
+                                             data, preUpdate);
         else if ((soe = llvm::dyn_cast<SizeOfExpr>(node)) != NULL)
-            soe->expr = (Expr *)WalkAST(soe->expr, preFunc, postFunc, data);
+            soe->expr = (Expr *)WalkAST(soe->expr, preFunc, postFunc, data, preUpdate);
         else if ((aoe = llvm::dyn_cast<AddressOfExpr>(node)) != NULL)
-            aoe->expr = (Expr *)WalkAST(aoe->expr, preFunc, postFunc, data);
+            aoe->expr = (Expr *)WalkAST(aoe->expr, preFunc, postFunc, data, preUpdate);
         else if ((newe = llvm::dyn_cast<NewExpr>(node)) != NULL) {
             newe->countExpr = (Expr *)WalkAST(newe->countExpr, preFunc,
-                                              postFunc, data);
+                                              postFunc, data, preUpdate);
             newe->initExpr = (Expr *)WalkAST(newe->initExpr, preFunc,
-                                             postFunc, data);
+                                             postFunc, data, preUpdate);
         }
         else if (llvm::dyn_cast<SymbolExpr>(node) != NULL ||
                  llvm::dyn_cast<ConstExpr>(node) != NULL ||
@@ -536,11 +540,21 @@ lTranslatePolyNode(ASTNode *node, void *d) {
     return node->ReplacePolyType(data->polyType, data->replacement);
 }
 
+static ASTNode *
+lCopyNode(ASTNode *node, void *) {
+    return node->Copy();
+}
+
 ASTNode *
 TranslatePoly(ASTNode *root, const PolyType *polyType, const Type *replacement) {
     struct PolyData data;
     data.polyType = polyType;
     data.replacement = replacement;
 
-    return WalkAST(root, NULL, lTranslatePolyNode, &data);
+    return WalkAST(root, NULL, lTranslatePolyNode, &data, lCopyNode);
+}
+
+ASTNode *
+CopyAST(ASTNode *root) {
+    return WalkAST(root, NULL, NULL, NULL, lCopyNode);
 }
diff --git a/ast.h b/ast.h
index 91d3dd5b..5c40454f 100644
--- a/ast.h
+++ b/ast.h
@@ -68,6 +68,8 @@ public:
         pointer in place of the original ASTNode *. */
     virtual ASTNode *TypeCheck() = 0;
 
+    virtual ASTNode *Copy() = 0;
+
     virtual ASTNode *ReplacePolyType(const PolyType *, const Type *) = 0;
 
     /** Estimate the execution cost of the node (not including the cost of
@@ -177,7 +179,8 @@ typedef ASTNode * (* ASTPostCallBackFunc)(ASTNode *node, void *data);
     doing so, calls postFunc, at the node.  The return value from the
     postFunc call is ignored. */
 extern ASTNode *WalkAST(ASTNode *root, ASTPreCallBackFunc preFunc,
-                        ASTPostCallBackFunc postFunc, void *data);
+                        ASTPostCallBackFunc postFunc, void *data,
+                        ASTPostCallBackFunc preUpdate = NULL);
 
 /** Perform simple optimizations on the AST or portion thereof passed to
     this function, returning the resulting AST. */
@@ -209,6 +212,8 @@ extern int EstimateCost(ASTNode *root);
 
 extern ASTNode * TranslatePoly(ASTNode *root, const PolyType *polyType, const Type *replacement);
 
+extern ASTNode * CopyAST(ASTNode *root);
+
 /** Returns true if it would be safe to run the given code with an "all
     off" mask. */
 extern bool SafeToRunWithMaskAllOff(ASTNode *root);
diff --git a/expr.cpp b/expr.cpp
index aed5d45c..8fe870c1 100644
--- a/expr.cpp
+++ b/expr.cpp
@@ -113,7 +113,7 @@ Expr::GetBaseSymbol() const {
 }
 
 Expr *
-Expr::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
+Expr::Copy() {
     Expr *copy;
     switch (getValueID()) {
         case AddressOfExprID:
@@ -128,9 +128,6 @@ Expr::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
         case ConstExprID:
             copy = (Expr*)new ConstExpr(*(ConstExpr*)this);
             break;
-        case SymbolExprID:
-            copy = (Expr*)new SymbolExpr(*(SymbolExpr*)this);
-            break;
         case PtrDerefExprID:
             copy = (Expr*)new PtrDerefExpr(*(PtrDerefExpr*)this);
             break;
@@ -143,6 +140,21 @@ Expr::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
         case FunctionCallExprID:
             copy = (Expr*)new FunctionCallExpr(*(FunctionCallExpr*)this);
             break;
+        case FunctionSymbolExprID:
+            copy = (Expr*)new FunctionSymbolExpr(*(FunctionSymbolExpr*)this);
+            break;
+        case IndexExprID:
+            copy = (Expr*)new IndexExpr(*(IndexExpr*)this);
+            break;
+        case StructMemberExprID:
+            copy = (Expr*)new StructMemberExpr(*(StructMemberExpr*)this);
+            break;
+        case VectorMemberExprID:
+            copy = (Expr*)new VectorMemberExpr(*(VectorMemberExpr*)this);
+            break;
+        case NewExprID:
+            copy = (Expr*)new NewExpr(*(NewExpr*)this);
+            break;
         case NullPointerExprID:
             copy = (Expr*)new NullPointerExpr(*(NullPointerExpr*)this);
             break;
@@ -155,16 +167,30 @@ Expr::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
         case SizeOfExprID:
             copy = (Expr*)new SizeOfExpr(*(SizeOfExpr*)this);
             break;
+        case SymbolExprID:
+            copy = (Expr*)new SymbolExpr(*(SymbolExpr*)this);
+            break;
+        case SyncExprID:
+            copy = (Expr*)new SyncExpr(*(SyncExpr*)this);
+            break;
+        case TypeCastExprID:
+            copy = (Expr*)new TypeCastExpr(*(TypeCastExpr*)this);
+            break;
         case UnaryExprID:
             copy = (Expr*)new UnaryExpr(*(UnaryExpr*)this);
             break;
         default:
-            FATAL("Unmatched case in ReplacePolyType (expr)");
+            FATAL("Unmatched case in Expr::Copy");
             copy = this; // just to silence the compiler
     }
     return copy;
 }
 
+Expr *
+Expr::ReplacePolyType(const PolyType *, const Type *) {
+    return this;
+}
+
 
 #if 0
 /** If a conversion from 'fromAtomicType' to 'toAtomicType' may cause lost
@@ -4196,14 +4222,6 @@ IndexExpr::IndexExpr(Expr *a, Expr *i, SourcePos p)
     type = lvalueType = NULL;
 }
 
-IndexExpr::IndexExpr(IndexExpr *base)
-    : Expr(base->pos, IndexExprID) {
-    baseExpr = base->baseExpr;
-    index = base->index;
-    type = base->type;
-    lvalueType = base->lvalueType;
-}
-
 
 /** When computing pointer values, we need to apply a per-lane offset when
     we have a varying pointer that is itself indexing into varying data.
@@ -4736,18 +4754,16 @@ IndexExpr::ReplacePolyType(const PolyType *from, const Type *to) {
     if (index == NULL || baseExpr == NULL)
         return NULL;
 
-    IndexExpr *copy = new IndexExpr(this);
-
-    if (Type::EqualForReplacement(copy->GetType()->GetBaseType(), from)) {
-        copy->type = PolyType::ReplaceType(type, to);
+    if (Type::EqualForReplacement(GetType()->GetBaseType(), from)) {
+        type = PolyType::ReplaceType(type, to);
     }
 
-    if (Type::EqualForReplacement(copy->GetLValueType()->GetBaseType(), from)) {
-        copy->lvalueType = new PointerType(to, copy->lvalueType->GetVariability(),
-                                           copy->lvalueType->IsConstType());
+    if (Type::EqualForReplacement(GetLValueType()->GetBaseType(), from)) {
+        lvalueType = new PointerType(to, lvalueType->GetVariability(),
+                                     lvalueType->IsConstType());
     }
 
-    return copy;
+    return this;
 }
 
 
@@ -4815,27 +4831,6 @@ lIdentifierToVectorElement(char id) {
 //////////////////////////////////////////////////
 // StructMemberExpr
 
-class StructMemberExpr : public MemberExpr
-{
-public:
-    StructMemberExpr(Expr *e, const char *id, SourcePos p,
-                     SourcePos idpos, bool derefLValue);
-
-    static inline bool classof(StructMemberExpr const*) { return true; }
-    static inline bool classof(ASTNode const* N) {
-        return N->getValueID() == StructMemberExprID;
-    }
-
-    const Type *GetType() const;
-    const Type *GetLValueType() const;
-    int getElementNumber() const;
-    const Type *getElementType() const;
-
-private:
-    const StructType *getStructType() const;
-};
-
-
 StructMemberExpr::StructMemberExpr(Expr *e, const char *id, SourcePos p,
                                    SourcePos idpos, bool derefLValue)
     : MemberExpr(e, id, p, idpos, derefLValue, StructMemberExprID) {
@@ -4987,31 +4982,6 @@ StructMemberExpr::getStructType() const {
 //////////////////////////////////////////////////
 // VectorMemberExpr
 
-class VectorMemberExpr : public MemberExpr
-{
-public:
-    VectorMemberExpr(Expr *e, const char *id, SourcePos p,
-                     SourcePos idpos, bool derefLValue);
-
-    static inline bool classof(VectorMemberExpr const*) { return true; }
-    static inline bool classof(ASTNode const* N) {
-        return N->getValueID() == VectorMemberExprID;
-    }
-
-    llvm::Value *GetValue(FunctionEmitContext* ctx) const;
-    llvm::Value *GetLValue(FunctionEmitContext* ctx) const;
-    const Type *GetType() const;
-    const Type *GetLValueType() const;
-
-    int getElementNumber() const;
-    const Type *getElementType() const;
-
-private:
-    const VectorType *exprVectorType;
-    const VectorType *memberType;
-};
-
-
 VectorMemberExpr::VectorMemberExpr(Expr *e, const char *id, SourcePos p,
                                    SourcePos idpos, bool derefLValue)
     : MemberExpr(e, id, p, idpos, derefLValue, VectorMemberExprID) {
@@ -5397,15 +5367,11 @@ MemberExpr::ReplacePolyType(const PolyType *from, const Type *to) {
     if (expr == NULL)
         return NULL;
 
-    MemberExpr *copy = getValueID() == StructMemberExprID ?
-        (MemberExpr*) new StructMemberExpr(*(StructMemberExpr*)this) :
-        (MemberExpr*) new VectorMemberExpr(*(VectorMemberExpr*)this);
-
-    if (Type::EqualForReplacement(copy->GetType()->GetBaseType(), from)) {
-        copy->type = PolyType::ReplaceType(copy->type, to);
+    if (Type::EqualForReplacement(GetType()->GetBaseType(), from)) {
+        type = PolyType::ReplaceType(type, to);
     }
 
-    return copy;
+    return this;
 }
 
 
@@ -6351,12 +6317,6 @@ TypeCastExpr::TypeCastExpr(const Type *t, Expr *e, SourcePos p)
     expr = e;
 }
 
-TypeCastExpr::TypeCastExpr(TypeCastExpr *base)
-    : Expr(base->pos, TypeCastExprID) {
-    type = base->type;
-    expr = base->expr;
-}
-
 
 /** Handle all the grungy details of type conversion between atomic types.
     Given an input value in exprVal of type fromType, convert it to the
@@ -7457,13 +7417,11 @@ TypeCastExpr::ReplacePolyType(const PolyType *from, const Type *to) {
     if (type == NULL)
         return NULL;
 
-    TypeCastExpr *copy = new TypeCastExpr(this);
-
-    if (Type::EqualForReplacement(copy->type->GetBaseType(), from)) {
-        copy->type = PolyType::ReplaceType(copy->type, to);
+    if (Type::EqualForReplacement(type->GetBaseType(), from)) {
+        type = PolyType::ReplaceType(type, to);
     }
 
-    return copy;
+    return this;
 }
 
 
@@ -8072,11 +8030,6 @@ SymbolExpr::SymbolExpr(Symbol *s, SourcePos p)
     symbol = s;
 }
 
-SymbolExpr::SymbolExpr(SymbolExpr *base)
-    : Expr(base->pos, SymbolExprID) {
-    symbol = base->symbol;
-}
-
 
 llvm::Value *
 SymbolExpr::GetValue(FunctionEmitContext *ctx) const {
@@ -8141,23 +8094,18 @@ SymbolExpr::Optimize() {
         return this;
 }
 
-/*
 Expr *
 SymbolExpr::ReplacePolyType(const PolyType *from, const Type *to) {
     if (!symbol)
         return NULL;
 
-    SymbolExpr *copy = new SymbolExpr(this);
-
-    //copy->symbol = new Symbol(*symbol);
 
     if (Type::EqualForReplacement(symbol->type->GetBaseType(), from)) {
-        copy->symbol->type = PolyType::ReplaceType(symbol->type, to);
+        symbol->type = PolyType::ReplaceType(symbol->type, to);
     }
 
-    return copy;
+    return this;
 }
-*/
 
 
 int
@@ -8760,14 +8708,6 @@ NewExpr::NewExpr(int typeQual, const Type *t, Expr *init, Expr *count,
         allocType = allocType->ResolveUnboundVariability(Variability::Uniform);
 }
 
-NewExpr::NewExpr(NewExpr *base)
-    : Expr(base->pos, NewExprID) {
-    allocType = base->allocType;
-    initExpr = base->initExpr;
-    countExpr = base->countExpr;
-    isVarying = base->isVarying;
-}
-
 
 llvm::Value *
 NewExpr::GetValue(FunctionEmitContext *ctx) const {
@@ -8970,13 +8910,11 @@ NewExpr::ReplacePolyType(const PolyType *from, const Type *to) {
     if (!allocType)
         return this;
 
-    NewExpr *copy = new NewExpr(this);
-
     if (Type::EqualForReplacement(allocType->GetBaseType(), from)) {
-        copy->allocType = PolyType::ReplaceType(allocType, to);
+        allocType = PolyType::ReplaceType(allocType, to);
     }
 
-    return copy;
+    return this;
 }
 
 
diff --git a/expr.h b/expr.h
index 9ee9710d..e80926e9 100644
--- a/expr.h
+++ b/expr.h
@@ -96,6 +96,7 @@ public:
         encountered, NULL should be returned. */
     virtual Expr *TypeCheck() = 0;
 
+    Expr *Copy();
 
     /** This method replaces a polymorphic type with a specific atomic type */
     Expr *ReplacePolyType(const PolyType *polyType, const Type *replacement);
@@ -334,7 +335,6 @@ public:
     Expr *baseExpr, *index;
 
 private:
-    IndexExpr(IndexExpr *base);
     mutable const Type *type;
     mutable const PointerType *lvalueType;
 };
@@ -386,6 +386,51 @@ protected:
     mutable const Type *type, *lvalueType;
 };
 
+class StructMemberExpr : public MemberExpr
+{
+public:
+    StructMemberExpr(Expr *e, const char *id, SourcePos p,
+                     SourcePos idpos, bool derefLValue);
+
+    static inline bool classof(StructMemberExpr const*) { return true; }
+    static inline bool classof(ASTNode const* N) {
+        return N->getValueID() == StructMemberExprID;
+    }
+
+    const Type *GetType() const;
+    const Type *GetLValueType() const;
+    int getElementNumber() const;
+    const Type *getElementType() const;
+
+private:
+    const StructType *getStructType() const;
+};
+
+
+class VectorMemberExpr : public MemberExpr
+{
+public:
+    VectorMemberExpr(Expr *e, const char *id, SourcePos p,
+                     SourcePos idpos, bool derefLValue);
+
+    static inline bool classof(VectorMemberExpr const*) { return true; }
+    static inline bool classof(ASTNode const* N) {
+        return N->getValueID() == VectorMemberExprID;
+    }
+
+    llvm::Value *GetValue(FunctionEmitContext* ctx) const;
+    llvm::Value *GetLValue(FunctionEmitContext* ctx) const;
+    const Type *GetType() const;
+    const Type *GetLValueType() const;
+
+    int getElementNumber() const;
+    const Type *getElementType() const;
+
+private:
+    const VectorType *exprVectorType;
+    const VectorType *memberType;
+};
+
 
 /** @brief Expression representing a compile-time constant value.
 
@@ -536,8 +581,6 @@ public:
 
     const Type *type;
     Expr *expr;
-private:
-    TypeCastExpr(TypeCastExpr *base);
 };
 
 
@@ -691,12 +734,11 @@ public:
     Symbol *GetBaseSymbol() const;
     Expr *TypeCheck();
     Expr *Optimize();
-    //Expr *ReplacePolyType(const PolyType *from, const Type *to);
+    Expr *ReplacePolyType(const PolyType *from, const Type *to);
     void Print() const;
     int EstimateCost() const;
 
 private:
-    SymbolExpr(SymbolExpr *base);
     Symbol *symbol;
 };
 
@@ -839,8 +881,6 @@ public:
         instance, or whether a single allocation is performed for the
         entire gang of program instances.) */
     bool isVarying;
-private:
-    NewExpr(NewExpr *base);
 };
 
 
diff --git a/func.cpp b/func.cpp
index da7ba0ca..9dca2b34 100644
--- a/func.cpp
+++ b/func.cpp
@@ -127,7 +127,6 @@ Function::Function(Symbol *s, Stmt *c) {
     const FunctionType *type = CastType<FunctionType>(sym->type);
     Assert(type != NULL);
 
-    printf("Function %s symbol types: ", sym->name.c_str());
     for (int i = 0; i < type->GetNumParameters(); ++i) {
         const char *paramName = type->GetParameterName(i).c_str();
         Symbol *sym = m->symbolTable->LookupVariable(paramName);
@@ -136,14 +135,10 @@ Function::Function(Symbol *s, Stmt *c) {
         args.push_back(sym);
 
         const Type *t = type->GetParameterType(i);
-        printf(" %s: %s==%s, ", sym->name.c_str(),
-                t->GetString().c_str(),
-                sym->type->GetString().c_str());
 
         if (sym != NULL && CastType<ReferenceType>(t) == NULL)
             sym->parentFunction = this;
     }
-    printf("\n");
 
     if (type->isTask
 #ifdef ISPC_NVPTX_ENABLED
@@ -657,14 +652,14 @@ Function::ExpandPolyArguments(SymbolTable *symbolTable) const {
 
     const FunctionType *func = CastType<FunctionType>(sym->type);
 
-    if (g->debugPrint) {
-        printf("%s before replacing anything:\n", sym->name.c_str());
-        code->Print(0);
-    }
-
     for (size_t i=0; i<versions.size(); i++) {
+        if (g->debugPrint) {
+            printf("%s before replacing anything:\n", sym->name.c_str());
+            code->Print(0);
+        }
         const FunctionType *ft = CastType<FunctionType>(versions[i]->type);
-        Stmt *ncode = code;
+
+        Stmt *ncode = (Stmt*)CopyAST(code);
 
         for (int j=0; j<ft->GetNumParameters(); j++) {
             if (func->GetParameterType(j)->IsPolymorphicType()) {
diff --git a/stmt.cpp b/stmt.cpp
index 0e116dba..0d84c704 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -35,6 +35,7 @@
     @brief File with definitions classes related to statements in the language
 */
 
+#include "ast.h"
 #include "stmt.h"
 #include "ctx.h"
 #include "util.h"
@@ -78,7 +79,7 @@ Stmt::Optimize() {
 }
 
 Stmt *
-Stmt::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
+Stmt::Copy() {
     Stmt *copy;
     switch (getValueID()) {
         case AssertStmtID:
@@ -93,6 +94,9 @@ Stmt::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
         case ContinueStmtID:
             copy = (Stmt*)new ContinueStmt(*(ContinueStmt*)this);
             break;
+        case DeclStmtID:
+            copy = (Stmt*)new DeclStmt(*(DeclStmt*)this);
+            break;
         case DefaultStmtID:
             copy = (Stmt*)new DefaultStmt(*(DefaultStmt*)this);
             break;
@@ -105,12 +109,12 @@ Stmt::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
         case ExprStmtID:
             copy = (Stmt*)new ExprStmt(*(ExprStmt*)this);
             break;
-        case ForeachStmtID:
-            copy = (Stmt*)new ForeachStmt(*(ForeachStmt*)this);
-            break;
         case ForeachActiveStmtID:
             copy = (Stmt*)new ForeachActiveStmt(*(ForeachActiveStmt*)this);
             break;
+        case ForeachStmtID:
+            copy = (Stmt*)new ForeachStmt(*(ForeachStmt*)this);
+            break;
         case ForeachUniqueStmtID:
             copy = (Stmt*)new ForeachUniqueStmt(*(ForeachUniqueStmt*)this);
             break;
@@ -142,12 +146,17 @@ Stmt::ReplacePolyType(const PolyType *polyType, const Type *replacement) {
             copy = (Stmt*)new UnmaskedStmt(*(UnmaskedStmt*)this);
             break;
         default:
-            FATAL("Unmatched case in ReplacePolyType (stmt)");
+            FATAL("Unmatched case in Stmt::Copy");
             copy = this; // just to silence the compiler
     }
     return copy;
 }
 
+Stmt *
+Stmt::ReplacePolyType(const PolyType *, const Type *) {
+    return this;
+}
+
 
 ///////////////////////////////////////////////////////////////////////////
 // ExprStmt
@@ -200,11 +209,6 @@ DeclStmt::DeclStmt(const std::vector<VariableDeclaration> &v, SourcePos p)
     : Stmt(p, DeclStmtID), vars(v) {
 }
 
-DeclStmt::DeclStmt(DeclStmt *base)
-    : Stmt(base->pos, DeclStmtID) {
-    vars = base->vars;
-}
-
 
 static bool
 lHasUnsizedArrays(const Type *type) {
@@ -572,16 +576,14 @@ DeclStmt::TypeCheck() {
 
 Stmt *
 DeclStmt::ReplacePolyType(const PolyType *from, const Type *to) {
-    DeclStmt *copy = new DeclStmt(this);
-
     for (size_t i = 0; i < vars.size(); i++) {
-        Symbol *s = copy->vars[i].sym;
+        Symbol *s = vars[i].sym;
         if (Type::EqualForReplacement(s->type->GetBaseType(), from)) {
             s->type = PolyType::ReplaceType(s->type, to);
         }
     }
 
-    return copy;
+    return this;
 }
 
 
@@ -2277,25 +2279,6 @@ ForeachStmt::TypeCheck() {
     return anyErrors ? NULL : this;
 }
 
-/*
-Stmt *
-ForeachStmt::ReplacePolyType(const PolyType *from, const Type *to) {
-    if (!stmts)
-        return NULL;
-
-    ForeachStmt *copy = new ForeachStmt(this);
-
-    for (size_t i=0; i<dimVariables.size(); i++) {
-        const Type *t = copy->dimVariables[i]->type;
-        if (Type::EqualForReplacement(t->GetBaseType(), from)) {
-            copy->dimVariables[i]->type = PolyType::ReplaceType(t, to);
-        }
-    }
-
-    return copy;
-}
-*/
-
 
 int
 ForeachStmt::EstimateCost() const {
diff --git a/stmt.h b/stmt.h
index ee2cd8fc..371f5915 100644
--- a/stmt.h
+++ b/stmt.h
@@ -70,6 +70,7 @@ public:
     // Stmts don't have anything to do here.
     virtual Stmt *Optimize();
     virtual Stmt *TypeCheck() = 0;
+    Stmt *Copy();
     Stmt *ReplacePolyType(const PolyType *polyType, const Type *replacement);
 };
 
@@ -122,8 +123,6 @@ public:
     int EstimateCost() const;
 
     std::vector<VariableDeclaration> vars;
-private:
-    DeclStmt(DeclStmt *base);
 };
 
 
@@ -285,7 +284,6 @@ public:
     void Print(int indent) const;
 
     Stmt *TypeCheck();
-    //Stmt *ReplacePolyType(const PolyType *from, const Type *to);
     int EstimateCost() const;
 
     std::vector<Symbol *> dimVariables;
@@ -293,8 +291,6 @@ public:
     std::vector<Expr *> endExprs;
     bool isTiled;
     Stmt *stmts;
-private:
-    //ForeachStmt(ForeachStmt *base);
 };