Rename member variables and functions and clarify comments to try to...

src/codegen-arm.cc

Index: src/codegen-arm.cc
===================================================================
--- src/codegen-arm.cc	(revision 547)
+++ src/codegen-arm.cc	(working copy)
@@ -1634,9 +1634,13 @@
 
   __ PushTryHandler(IN_JAVASCRIPT, TRY_CATCH_HANDLER);
 
-  // Introduce shadow labels for all escapes from the try block,
-  // including returns. We should probably try to unify the escaping
-  // labels and the return label.
+  // Shadow the labels for all escapes from the try block, including
+  // returns. During shadowing, the origianl label is hidden as the

[iposva, 2008/10/22 18:34:33]

origianl -> original

+  // LabelShadow and operations on the original actually affect the
+  // shadowing label.
+  //
+  // We should probably try to unify the escaping labels and the return
+  // label.
   int nof_escapes = node->escaping_labels()->length();
   List<LabelShadow*> shadows(1 + nof_escapes);
   shadows.Add(new LabelShadow(&function_return_));
@@ -1649,6 +1653,8 @@
   __ pop(r0);  // Discard the result.
 
   // Stop the introduced shadowing and count the number of required unlinks.
+  // After shadowing stops, the original labels are unshadowed and the
+  // LabelShadows represent the formerly shadowing labels.
   int nof_unlinks = 0;
   for (int i = 0; i <= nof_escapes; i++) {
     shadows[i]->StopShadowing();
@@ -1667,7 +1673,8 @@
   // Code slot popped.
   if (nof_unlinks > 0) __ b(&exit);
 
-  // Generate unlink code for all used shadow labels.
+  // Generate unlink code for the (formerly) shadowing labels that have been
+  // jumped to.
   for (int i = 0; i <= nof_escapes; i++) {
     if (shadows[i]->is_linked()) {
       // Unlink from try chain;
@@ -1684,7 +1691,7 @@
       __ add(sp, sp, Operand(StackHandlerConstants::kSize - kPointerSize));
       // Code slot popped.
 
-      __ b(shadows[i]->shadowed());
+      __ b(shadows[i]->original_label());
     }
   }
 
@@ -1715,9 +1722,12 @@
 
   __ PushTryHandler(IN_JAVASCRIPT, TRY_FINALLY_HANDLER);
 
-  // Introduce shadow labels for all escapes from the try block,
-  // including returns. We should probably try to unify the escaping
-  // labels and the return label.
+  // Shadow the labels for all escapes from the try block, including
+  // returns. Shadowing hides the original label as the LabelShadow and
+  // operations on the original actually affect the shadowing label.
+  //
+  // We should probably try to unify the escaping labels and the return
+  // label.
   int nof_escapes = node->escaping_labels()->length();
   List<LabelShadow*> shadows(1 + nof_escapes);
   shadows.Add(new LabelShadow(&function_return_));
@@ -1728,8 +1738,9 @@
   // Generate code for the statements in the try block.
   VisitStatements(node->try_block()->statements());
 
-  // Stop the introduced shadowing and count the number of required
-  // unlinks.
+  // Stop the introduced shadowing and count the number of required unlinks.
+  // After shadowing stops, the original labels are unshadowed and the
+  // LabelShadows represent the formerly shadowing labels.
   int nof_unlinks = 0;
   for (int i = 0; i <= nof_escapes; i++) {
     shadows[i]->StopShadowing();
@@ -1742,14 +1753,17 @@
   __ mov(r2, Operand(Smi::FromInt(FALLING)));
   if (nof_unlinks > 0) __ b(&unlink);
 
-  // Generate code that sets the state for all used shadow labels.
+  // Generate code to set the state for the (formerly) shadowing labels that
+  // have been jumped to.
   for (int i = 0; i <= nof_escapes; i++) {
     if (shadows[i]->is_linked()) {
       __ bind(shadows[i]);
-      if (shadows[i]->shadowed() == &function_return_) {
-        __ push(r0);  // Materialize the return value on the stack
+      if (shadows[i]->original_label() == &function_return_) {
+        // If this label shadowed the function return, materialize the
+        // return value on the stack.
+        __ push(r0);
       } else {
-        // Fake TOS for break and continue (not return).
+        // Fake TOS for labels that shadowed breaks and continues.
         __ mov(r0, Operand(Factory::undefined_value()));
         __ push(r0);
       }
@@ -1796,18 +1810,18 @@
   __ pop(r0);
   break_stack_height_ -= kFinallyStackSize;
 
-  // Generate code that jumps to the right destination for all used
-  // shadow labels.
+  // Generate code to jump to the right destination for all used (formerly)
+  // shadowing labels.
   for (int i = 0; i <= nof_escapes; i++) {
     if (shadows[i]->is_bound()) {
       __ cmp(r2, Operand(Smi::FromInt(JUMPING + i)));
-      if (shadows[i]->shadowed() != &function_return_) {
+      if (shadows[i]->original_label() != &function_return_) {
         Label next;
         __ b(ne, &next);
-        __ b(shadows[i]->shadowed());
+        __ b(shadows[i]->original_label());
         __ bind(&next);
       } else {
-        __ b(eq, shadows[i]->shadowed());
+        __ b(eq, shadows[i]->original_label());
       }
     }
   }