Generate smaller unoptimized code for certain expressions.

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 3412 matching lines @@
   virtual bool MayThrow() const {
     UNREACHABLE();
     return false;
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PushTempInstr);
 };
 
 
-class DropTempsInstr : public TemplateDefinition<1> {
+class DropTempsInstr : public Definition {
  public:
-  explicit DropTempsInstr(intptr_t num_temps, Value* value)
-      : num_temps_(num_temps) {
-    SetInputAt(0, value);
+  explicit DropTempsInstr(intptr_t num_temps, Value* value = NULL)
+      : num_temps_(num_temps), value_(NULL) {
+    if (value != NULL) {
+      SetInputAt(0, value);

[srdjan, 2014/03/12 18:18:30]

I think it would be better do add a private method SetValue which would do:
value->set_instruction(this);
value->set_use_index(i)

[Florian Schneider, 2014/03/13 08:56:15]

I would still need RawSetInputAt since it is used by SetInputAt. I'll rather
have  the use-list book-keeping in once place.

+    }
   }
 
   DECLARE_INSTRUCTION(DropTemps)
 
-  Value* value() const { return inputs_[0]; }
+  virtual intptr_t InputCount() const { return value_ != NULL ? 1 : 0; }
+  virtual Value* InputAt(intptr_t i) const {
+    ASSERT((value_ != NULL) && (i == 0));
+    return value_;
+  }
+
+  Value* value() const { return value_; }
 
   intptr_t num_temps() const { return num_temps_; }
 
   virtual CompileType* ComputeInitialType() const;
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
   virtual bool CanDeoptimize() const { return false; }
 
   virtual EffectSet Effects() const {
     UNREACHABLE();  // Eliminated by SSA construction.
     return EffectSet::None();
   }
 
   virtual bool MayThrow() const {
     UNREACHABLE();
     return false;
   }
 
  private:
+  virtual void RawSetInputAt(intptr_t i, Value* value) {
+    value_ = value;
+  }
+
   intptr_t num_temps_;

[srdjan, 2014/03/12 18:18:30]

const ?

[Florian Schneider, 2014/03/13 08:56:15]

Done.

+  Value* value_;
 
   DISALLOW_COPY_AND_ASSIGN(DropTempsInstr);
 };
 
 
 class StoreLocalInstr : public TemplateDefinition<1> {
  public:
   StoreLocalInstr(const LocalVariable& local, Value* value)
       : local_(local), is_dead_(false), is_last_(false) {
     SetInputAt(0, value);
@@ skipping 4230 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_