VM: Remove unnecessary field use_kind from IL instructions.

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 1731 matching lines @@
 enum AliasIdentity {
   kIdentityUnknown,
   kIdentityAliased,
   kIdentityNotAliased
 };
 
 
 // Abstract super-class of all instructions that define a value (Bind, Phi).
 class Definition : public Instruction {
  public:
-  enum UseKind { kEffect, kValue };
-
   Definition();
 
   virtual Definition* AsDefinition() { return this; }
 
   bool IsComparison() { return (AsComparison() != NULL); }
   virtual ComparisonInstr* AsComparison() { return NULL; }
 
   // Overridden by definitions that push arguments.
   virtual intptr_t ArgumentCount() const { return 0; }
 
   // Overridden by definitions that have call counts.
   virtual intptr_t CallCount() const {
     UNREACHABLE();
     return -1;
   }
 
   intptr_t temp_index() const { return temp_index_; }
   void set_temp_index(intptr_t index) { temp_index_ = index; }
   void ClearTempIndex() { temp_index_ = -1; }
+  bool HasTemp() const { return temp_index_ >= 0; }
 
   intptr_t ssa_temp_index() const { return ssa_temp_index_; }
   void set_ssa_temp_index(intptr_t index) {
     ASSERT(index >= 0);
-    ASSERT(is_used());
     ssa_temp_index_ = index;
   }
   bool HasSSATemp() const { return ssa_temp_index_ >= 0; }

[srdjan, 2014/05/20 16:03:48]

Do we want to make a comment somewhere that only definitions which results is
used have an SSA temp?

[Florian Schneider, 2014/05/21 14:03:45]

In SSA form, we have use lists to check where a definition is used. In
unoptimized code, the temp index is used for this purpose.

   void ClearSSATempIndex() { ssa_temp_index_ = -1; }
   bool HasPairRepresentation() const {
     return (representation() == kPairOfTagged) ||
            (representation() == kPairOfUnboxedDouble);
   }
-  bool is_used() const { return (use_kind_ != kEffect); }
-  void set_use_kind(UseKind kind) { use_kind_ = kind; }
 
   // Compile time type of the definition, which may be requested before type
   // propagation during graph building.
   CompileType* Type() {
     if (type_ == NULL) {
       type_ = ComputeInitialType();
     }
     return type_;
   }
 
@@ skipping 105 matching lines @@
   friend class Value;
 
   Range* range_;
   CompileType* type_;
 
  private:
   intptr_t temp_index_;
   intptr_t ssa_temp_index_;
   Value* input_use_list_;
   Value* env_use_list_;
-  UseKind use_kind_;
 
   Object& constant_value_;
 
   DISALLOW_COPY_AND_ASSIGN(Definition);
 };
 
 
 // Change a value's definition after use lists have been computed.
 inline void Value::BindTo(Definition* def) {
   RemoveFromUseList();
@@ skipping 141 matching lines @@
   BlockEntryInstr* block_;
 
   DISALLOW_COPY_AND_ASSIGN(ParameterInstr);
 };
 
 
 class PushArgumentInstr : public Definition {
  public:
   explicit PushArgumentInstr(Value* value) {
     SetInputAt(0, value);
-    set_use_kind(kEffect);  // Override the default.
   }
 
   DECLARE_INSTRUCTION(PushArgument)
 
   intptr_t InputCount() const { return 1; }
   Value* InputAt(intptr_t i) const {
     ASSERT(i == 0);
     return value_;
   }
 
@@ skipping 5879 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_