Indirectly dispatch all backtracking jumps through the same block.

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, 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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 2173 matching lines @@
 };
 
 
 // IndirectGotoInstr represents a dynamically computed jump. Only
 // IndirectEntryInstr targets are valid targets of an indirect goto. The
 // concrete target to jump to is given as a parameter to the indirect goto.
 //
 // In order to preserve split-edge form, an indirect goto does not itself point
 // to its targets. Instead, for each possible target, the successors_ field
 // will contain an ordinary goto instruction that jumps to the target.
+// TODO(zerny): Implement direct support instead of embedding gotos.
 //
 // Byte offsets of all possible targets are stored in the offsets_ array. The
 // desired offset is looked up while the generated code is executing, and passed
 // to IndirectGoto as an input.
 class IndirectGotoInstr : public TemplateInstruction<1, NoThrow> {
  public:
   IndirectGotoInstr(GrowableObjectArray* offsets,
                     Value* offset_from_start)
     : offsets_(*offsets) {
     SetInputAt(0, offset_from_start);
@@ skipping 16 matching lines @@
   }
 
   virtual bool CanDeoptimize() const { return false; }
   virtual bool CanBecomeDeoptimizationTarget() const { return false; }
 
   virtual EffectSet Effects() const { return EffectSet::None(); }
 
   virtual void PrintTo(BufferFormatter* f) const;
 
   const GrowableObjectArray& offsets() const { return offsets_; }
-  void SetOffsetCount(Isolate* isolate, intptr_t count) {
-    if (offsets_.Capacity() < count) {
-      offsets_.Grow(count, Heap::kOld);
-    }
-    if (offsets_.Length() < count) {
-      offsets_.SetLength(count);
-    }
-  }
-  void SetOffsetAt(Isolate* isolate, intptr_t index, intptr_t offset) {
-    offsets_.SetAt(index, Smi::ZoneHandle(isolate, Smi::New(offset)));
-  }
+  void ComputeOffsetTable(Isolate* isolate);
 
  private:
   GrowableArray<TargetEntryInstr*> successors_;
   GrowableObjectArray& offsets_;
 };
 
 
 class ComparisonInstr : public TemplateDefinition<2, NoThrow, Pure> {
  public:
   Value* left() const { return inputs_[0]; }
@@ skipping 5731 matching lines @@
       Isolate* isolate, bool opt) const {                                     \
     UNIMPLEMENTED();                                                          \
     return NULL;                                                              \
   }                                                                           \
   void Name::EmitNativeCode(FlowGraphCompiler* compiler) { UNIMPLEMENTED(); }
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_