diff --git a/src/script_opt/DefSetsMgr.cc b/src/script_opt/DefSetsMgr.cc
index 27229f9cb6..dd332b21af 100644
--- a/src/script_opt/DefSetsMgr.cc
+++ b/src/script_opt/DefSetsMgr.cc
@@ -41,7 +41,7 @@ void DefSetsMgr::CreatePostDef(std::shared_ptr<DefinitionItem> di,
 		SetPostFromPre(where);
 		}
 
-	CreateDef(di, dp, false, min_only);
+	CreateDef(std::move(di), dp, false, min_only);
 	}
 
 void DefSetsMgr::CreateDef(std::shared_ptr<DefinitionItem> di,
diff --git a/src/script_opt/DefSetsMgr.h b/src/script_opt/DefSetsMgr.h
index 435f6f2b39..eb2993fc60 100644
--- a/src/script_opt/DefSetsMgr.h
+++ b/src/script_opt/DefSetsMgr.h
@@ -95,8 +95,8 @@ public:
 	// Set the post-RDs for a given node to the given min/max values.
 	void SetPostRDs(const Obj* o, RDPtr min_rd, RDPtr max_rd)
 		{
-		SetPostMinRDs(o, min_rd);
-		SetPostMaxRDs(o, max_rd);
+		SetPostMinRDs(o, std::move(min_rd));
+		SetPostMaxRDs(o, std::move(max_rd));
 		}
 
 	// Propagate the node's pre-RDs to also be its post-RDs.
@@ -122,14 +122,14 @@ public:
 
 	// Fine-grained control for setting RDs.
 	void SetPreMinRDs(const Obj* o, RDPtr rd)
-		{ pre_min_defs->SetRDs(o, rd); }
+		{ pre_min_defs->SetRDs(o, std::move(rd)); }
 	void SetPreMaxRDs(const Obj* o, RDPtr rd)
-		{ pre_max_defs->SetRDs(o, rd); }
+		{ pre_max_defs->SetRDs(o, std::move(rd)); }
 
 	void SetPostMinRDs(const Obj* o, RDPtr rd)
-		{ post_min_defs->SetRDs(o, rd); }
+		{ post_min_defs->SetRDs(o, std::move(rd)); }
 	void SetPostMaxRDs(const Obj* o, RDPtr rd)
-		{ post_max_defs->SetRDs(o, rd); }
+		{ post_max_defs->SetRDs(o, std::move(rd)); }
 
 	// Used for confluence: add a set of RDs into those already
 	// associated with a node's pre-RDs / post-RDs.  Only applies
@@ -172,7 +172,7 @@ public:
 	// then only done for minimal RDs.
 	void CreatePreDef(std::shared_ptr<DefinitionItem> di,
 				DefinitionPoint dp, bool min_only)
-		{ CreateDef(di, dp, true, min_only); }
+		{ CreateDef(std::move(di), dp, true, min_only); }
 	void CreatePostDef(const ID* id, DefinitionPoint dp, bool min_only);
 	void CreatePostDef(std::shared_ptr<DefinitionItem> di,
 				DefinitionPoint dp, bool min_only);
diff --git a/src/script_opt/GenRDs.cc b/src/script_opt/GenRDs.cc
index 5979be09ba..d41f90c18e 100644
--- a/src/script_opt/GenRDs.cc
+++ b/src/script_opt/GenRDs.cc
@@ -20,9 +20,9 @@ public:
 	BlockDefs(bool _is_case)
 		{ is_case = _is_case; }
 
-	void AddPreRDs(RDPtr RDs)	{ pre_RDs.push_back(RDs); }
-	void AddPostRDs(RDPtr RDs)	{ post_RDs.push_back(RDs); }
-	void AddFutureRDs(RDPtr RDs)	{ future_RDs.push_back(RDs); }
+	void AddPreRDs(RDPtr RDs)	{ pre_RDs.push_back(std::move(RDs)); }
+	void AddPostRDs(RDPtr RDs)	{ post_RDs.push_back(std::move(RDs)); }
+	void AddFutureRDs(RDPtr RDs)	{ future_RDs.push_back(std::move(RDs)); }
 
 	const std::vector<RDPtr>& PreRDs() const	{ return pre_RDs; }
 	const std::vector<RDPtr>& PostRDs() const	{ return post_RDs; }
@@ -48,12 +48,12 @@ void RD_Decorate::TraverseFunction(const Func* f, Scope* scope, StmtPtr body)
 	{
 	func_flavor = f->Flavor();
 
-	auto args = scope->OrderedVars();
+	const auto& args = scope->OrderedVars();
 	int nparam = f->GetType()->Params()->NumFields();
 
 	mgr.SetEmptyPre(f);
 
-	for ( auto a : args )
+	for ( const auto& a : args )
 		{
 		if ( --nparam < 0 )
 			break;
@@ -141,7 +141,7 @@ TraversalCode RD_Decorate::PreStmt(const Stmt* s)
 	case STMT_LIST:
 		{
 		auto sl = s->AsStmtList();
-		auto stmts = sl->Stmts();
+		const auto& stmts = sl->Stmts();
 		const Stmt* pred_stmt = s;	// current Stmt's predecessor
 
 		for ( const auto& stmt : stmts )
@@ -723,9 +723,8 @@ bool RD_Decorate::CheckLHS(const Expr* lhs, const Expr* e)
 		auto fn = f->FieldName();
 
 		auto field_rd = r_def->FindField(fn);
-		auto ft = f->GetType();
 		if ( ! field_rd )
-			field_rd = r_def->CreateField(fn, ft);
+			field_rd = r_def->CreateField(fn, f->GetType());
 
 		CreateInitPostDef(field_rd, DefinitionPoint(e), false, rhs.get());
 
@@ -942,9 +941,8 @@ TraversalCode RD_Decorate::PreExpr(const Expr* e)
 		auto offset = f->Field();
 		auto field_rd = r_def->FindField(offset);
 
-		auto ft = f->GetType();
 		if ( ! field_rd )
-			field_rd = r_def->CreateField(offset, ft);
+			field_rd = r_def->CreateField(offset, f->GetType());
 
 		CreateInitPostDef(field_rd, DefinitionPoint(e), false, r);
 
@@ -1031,7 +1029,7 @@ TraversalCode RD_Decorate::PreExpr(const Expr* e)
 			if ( ! field_rd )
 				{
 				auto ft = id_rt->GetFieldType(fn);
-				field_rd = id_di->CreateField(fn, ft);
+				field_rd = id_di->CreateField(fn, std::move(ft));
 				CreateInitPostDef(field_rd, DefinitionPoint(hf),
 							false, 0);
 				}
@@ -1189,7 +1187,7 @@ void RD_Decorate::CreateInitPostDef(std::shared_ptr<DefinitionItem> di,
 					DefinitionPoint dp, bool assume_full,
 					const Expr* rhs)
 	{
-	CreateInitDef(di, dp, false, assume_full, rhs);
+	CreateInitDef(std::move(di), dp, false, assume_full, rhs);
 	}
 
 void RD_Decorate::CreateInitDef(std::shared_ptr<DefinitionItem> di,
@@ -1225,7 +1223,7 @@ void RD_Decorate::CreateInitDef(std::shared_ptr<DefinitionItem> di,
 			}
 		}
 
-	CreateRecordRDs(di, dp, is_pre, assume_full, rhs_di.get());
+	CreateRecordRDs(std::move(di), dp, is_pre, assume_full, rhs_di.get());
 	}
 
 void RD_Decorate::CreateRecordRDs(std::shared_ptr<DefinitionItem> di,
@@ -1239,7 +1237,7 @@ void RD_Decorate::CreateRecordRDs(std::shared_ptr<DefinitionItem> di,
 	for ( auto i = 0; i < n; ++i )
 		{
 		auto n_i = rt->FieldName(i);
-		auto t_i = rt->GetFieldType(i);
+		const auto& t_i = rt->GetFieldType(i);
 		auto rhs_di_i = rhs_di ? rhs_di->FindField(n_i) : nullptr;
 
 		bool field_is_defined = false;
@@ -1323,7 +1321,7 @@ void RD_Decorate::CheckRecordRDs(std::shared_ptr<DefinitionItem> di,
 			// very heavy if run on the full code base because
 			// there are some massive records (in some places
 			// nested 5 deep).
-			auto t_i = rt->GetFieldType(i);
+			const auto& t_i = rt->GetFieldType(i);
 			if ( t_i->Tag() == TYPE_RECORD )
 				CheckRecordRDs(field_di, dp, pre_rds, o);
 			}
diff --git a/src/script_opt/GenRDs.h b/src/script_opt/GenRDs.h
index ae3f1629ab..d75b431924 100644
--- a/src/script_opt/GenRDs.h
+++ b/src/script_opt/GenRDs.h
@@ -75,7 +75,7 @@ private:
 	void CreateRecordRDs(std::shared_ptr<DefinitionItem> di,
 				DefinitionPoint dp, bool assume_full,
 				const DefinitionItem* rhs_di)
-		{ CreateRecordRDs(di, dp, false, assume_full, rhs_di); }
+		{ CreateRecordRDs(std::move(di), dp, false, assume_full, rhs_di); }
 	void CreateRecordRDs(std::shared_ptr<DefinitionItem> di,
 				DefinitionPoint dp, bool is_pre,
 				bool assume_full, const DefinitionItem* rhs_di);
diff --git a/src/script_opt/ReachingDefs.cc b/src/script_opt/ReachingDefs.cc
index 9ba24c4ba0..061982418f 100644
--- a/src/script_opt/ReachingDefs.cc
+++ b/src/script_opt/ReachingDefs.cc
@@ -13,9 +13,9 @@ ReachingDefs::ReachingDefs()
 	const_rd_map = nullptr;
 	}
 
-ReachingDefs::ReachingDefs(RDPtr& rd)
+ReachingDefs::ReachingDefs(RDPtr rd)
 	{
-	const_rd_map = rd;
+	const_rd_map = std::move(rd);
 	my_rd_map = nullptr;
 	}
 
diff --git a/src/script_opt/ReachingDefs.h b/src/script_opt/ReachingDefs.h
index 0d78784a19..ed01d08e14 100644
--- a/src/script_opt/ReachingDefs.h
+++ b/src/script_opt/ReachingDefs.h
@@ -39,7 +39,7 @@ public:
 	ReachingDefs();
 
 	// Create a new object, using the RDs from another object.
-	ReachingDefs(RDPtr& rd);
+	ReachingDefs(RDPtr rd);
 
 	~ReachingDefs();
 
@@ -208,9 +208,9 @@ public:
 	RDPtr& FindRDs(const Obj* o) const;
 
 	// Associates the given RDs with the given AST node.
-	void SetRDs(const Obj* o, RDPtr& rd)
+	void SetRDs(const Obj* o, RDPtr rd)
 		{
-		auto new_rd = make_intrusive<ReachingDefs>(rd);
+		auto new_rd = make_intrusive<ReachingDefs>(std::move(rd));
 		(*a_i)[o] = new_rd;
 		}