Optimize functions containing try-catch.

runtime/vm/scopes.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SCOPES_H_
 #define VM_SCOPES_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/growable_array.h"
@@ skipping 14 matching lines @@
                 const String& name,
                 const AbstractType& type)
     : token_pos_(token_pos),
       name_(name),
       owner_(NULL),
       type_(type),
       const_value_(NULL),
       is_final_(false),
       is_captured_(false),
       is_invisible_(false),
+      always_live_(false),
       index_(LocalVariable::kUnitializedIndex) {
     ASSERT(type.IsZoneHandle());
     ASSERT(type.IsFinalized());
   }
 
   intptr_t token_pos() const { return token_pos_; }
   const String& name() const { return name_; }
   LocalScope* owner() const { return owner_; }
   void set_owner(LocalScope* owner) {
     ASSERT(owner_ == NULL);
@@ skipping 20 matching lines @@
   void set_index(int index) {
     ASSERT(!HasIndex());
     ASSERT(index != kUnitializedIndex);
     index_ = index;
   }
 
   void set_invisible(bool value) {
     is_invisible_ = value;
   }
 
+  bool always_live() const { return always_live_; }

[Kevin Millikin (Google), 2013/05/08 11:42:00]

This needs a comment that is is, for example, for things like the catch context
variable, catch stack trace variable, etc.

[Florian Schneider, 2013/05/08 17:10:55]

Done.

+  void mark_as_always_live() { always_live_ = true; }
+
   bool IsConst() const {
     return const_value_ != NULL;
   }
 
   void SetConstValue(const Instance& value) {
     ASSERT(value.IsZoneHandle() || value.IsReadOnlyHandle());
     const_value_ = &value;
   }
 
   const Instance* ConstValue() const {
@@ skipping 17 matching lines @@
   LocalScope* owner_;  // Local scope declaring this variable.
 
   const AbstractType& type_;  // Declaration type of local variable.
 
   const Instance* const_value_;   // NULL or compile-time const value.
 
   bool is_final_;  // If true, this variable is readonly.
   bool is_captured_;  // If true, this variable lives in the context, otherwise
                       // in the stack frame.
   bool is_invisible_;
+  bool always_live_;
   int index_;  // Allocation index in words relative to frame pointer (if not
                // captured), or relative to the context pointer (if captured).
 
   friend class LocalScope;
   DISALLOW_COPY_AND_ASSIGN(LocalVariable);
 };
 
 
 class SourceLabel : public ZoneAllocated {
  public:
@@ skipping 239 matching lines @@
   intptr_t end_token_pos_;    // Token index of end of scope.
   GrowableArray<LocalVariable*> variables_;
   GrowableArray<SourceLabel*> labels_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalScope);
 };
 
 }  // namespace dart
 
 #endif  // VM_SCOPES_H_