Strict mode arguments do not share binding with formal parameters.

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index 5f5de3a9f93fbf71c214ac517c6d69bd1b753535..80b275cdb0b7103582598d56e2111470f6849628 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -212,11 +212,18 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
     // stack frame was an arguments adapter frame.
     ArgumentsAccessStub stub(ArgumentsAccessStub::NEW_OBJECT);
     __ CallStub(&stub);
-    // Duplicate the value; move-to-slot operation might clobber registers.
-    __ mov(r3, r0);
-    Move(arguments->AsSlot(), r0, r1, r2);
-    Slot* dot_arguments_slot = scope()->arguments_shadow()->AsSlot();
-    Move(dot_arguments_slot, r3, r1, r2);
+
+    Variable* arguments_shadow = scope()->arguments_shadow();
+    if (arguments_shadow != NULL) {

[Kevin Millikin (Chromium), 2011/03/07 11:46:48]

A bit simpler (also on the other platforms):

if (arguments_shadow != NULL) {
  // Duplicate the value; move-to-slot operation might clobber registers.
  __ mov(r3, r0);
  Move(arguments_shadow->AsSlot(), r3, r1, r2);
}
Move(arguments->AsSlot(), r0, r1, r2);

[Martin Maly, 2011/03/07 19:09:40]

Done.

+      // Duplicate the value; move-to-slot operation might clobber registers.
+      __ mov(r3, r0);
+      Move(arguments->AsSlot(), r0, r1, r2);
+      Move(arguments_shadow->AsSlot(), r3, r1, r2);
+    } else {
+      // arguments are allocated without shadow only in strict mode.
+      ASSERT(scope()->is_strict_mode());
+      Move(arguments->AsSlot(), r0, r1, r2);
+    }
   }
 
   if (FLAG_trace) {