diff -r bb419abf0df4 -r 153d0cafc1fd src/BytecodeCompiler.cpp
--- a/src/BytecodeCompiler.cpp	Sat Aug 04 21:47:30 2012 -0700
+++ b/src/BytecodeCompiler.cpp	Sat Aug 04 23:26:49 2012 -0700
@@ -201,6 +201,8 @@
 void
 BytecodeCompiler::visit(Assignment *node)
 {
+    Local<Type> type(zone_, node->expression()->type());
+
     // The first step is three sub-steps:
     //
     //   (1) Bind the left-hand side.
@@ -213,8 +215,12 @@
         Variable *var = proxy->binding()->toVariable();
 
         // Bind.
-        if (var->type()->isReference() || var->type()->isArray())
+        if (var->type()->isReference() ||
+            var->type()->isArray() ||
+            var->type()->isStruct())
+        {
             __ get(var);
+        }
 
         // Get the value if needed.
         if (node->token() != TOK_ASSIGN) {
@@ -234,15 +240,16 @@
 
         expr->left()->accept(this);
 
-        if (node->token() != TOK_ASSIGN) {
+        if (node->token() != TOK_ASSIGN)
             __ dup();
+
+        if (node->token() != TOK_ASSIGN || (type->isStruct() || type->isArray()))
             __ getfield(expr->fieldIndex(), expr->type());
-        }
     } else {
         IndexExpression *index = node->lvalue()->toIndexExpression();
         __ note_position(index->pos());
 
-        // Note: Eventually, watch out for a whole here. An expression like:
+        // Note: Eventually, watch out for a hole here. An expression like:
         //
         //   (a[4] = (5, a = []))
         //
@@ -252,13 +259,12 @@
         index->left()->accept(this);
         index->right()->accept(this);
 
-        if (node->token() != TOK_ASSIGN) {
+        if (node->token() != TOK_ASSIGN)
             __ dup2();
+
+        if (node->token() != TOK_ASSIGN || (type->isStruct() || type->isArray())) {
             __ bounds();
-            if (node->type()->isArray())
-                __ getarray_o();
-            else
-                __ getarray(node->type());
+            __ getarray(index->type());
         }
     }
 
@@ -273,11 +279,16 @@
     }
 
     // Emit the store.
-    if (node->expression()->type()->isArray()) {
+    if (type->isArray()) {
         // Unlike references, which can only be computed from a NamePRoxy,
         // arrays can be computed from multiple lvalue types.
         __ note_position(node->pos());
-        __ arraycopy();
+        __ copyarray();
+    } else if (type->isStruct()) {
+        // Structs have value semantics, so emit a full copy. We don't break
+        // this down into u-ops, to avoid unnecessary bytecode explosion.
+        __ note_position(node->pos());
+        __ copystruct();
     } else if (node->lvalue()->isNameProxy()) {
         NameProxy *proxy = node->lvalue()->toNameProxy();
         Variable *var = proxy->binding()->toVariable();
@@ -793,7 +804,7 @@
         if (node->initialization()) {
             node->initialization()->accept(this);
             __ note_position(node->pos());
-            __ arraycopy();
+            __ copyarray();
         }
     } else if (type->isStruct()) {
         Local<Map> map(zone_, type->newMap());