2 files changed, 4 insertions, 1 deletions
diff --git a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
index d9726d28..ec040b4f 100644
--- a/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/chapter15/src/main/java/com/seaofnodes/simple/Parser.java
@@ -711,6 +711,8 @@ public class Parser {
 
     private Node newArray(Type t) {
         Node len = parseExpression().keep();
+        if( !(len._type instanceof TypeInteger) )
+            throw error("Cannot allocate an array with length "+len._type);
         TypeStruct ary = (TypeStruct)TYPES.get("[]"+t.str());
         if( ary == null ) {
             TYPES.put("[]"+t.str(), ary = TypeStruct.makeAry(TypeInteger.BOT,ALIAS++,t,ALIAS++));
diff --git a/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java b/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
index 444b76a8..e12f1fef 100644
--- a/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
+++ b/chapter15/src/main/java/com/seaofnodes/simple/node/ReturnNode.java
@@ -17,7 +17,8 @@ public class ReturnNode extends CFGNode {
 
     public ReturnNode(Node ctrl, Node data, ScopeNode scope) {
         super(ctrl, data);
-        // We lookup memory slices by the naming convention that they start with $
+        // Add memory slices to Return, so all memory updates are live-on-exit.
+        // We look up memory slices by the naming convention that they start with $.
         // We could also use implicit knowledge that all memory projects are at offset >= 2
         if( scope != null ) {
             String[] names = scope.reverseNames();