SSI implementation.

src/hydrogen-instructions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 46 matching lines @@
   V(BinaryOperation)                           \
   V(BitwiseBinaryOperation)                    \
   V(ControlInstruction)                        \
   V(Instruction)                               \
 
 
 #define HYDROGEN_CONCRETE_INSTRUCTION_LIST(V)  \
   V(AbnormalExit)                              \
   V(AccessArgumentsAt)                         \
   V(Add)                                       \
+  V(SsiDefinition)                             \
   V(AllocateObject)                            \
   V(ApplyArguments)                            \
   V(ArgumentsElements)                         \
   V(ArgumentsLength)                           \
   V(ArgumentsObject)                           \
   V(ArrayLiteral)                              \
   V(Bitwise)                                   \
   V(BitNot)                                    \
   V(BlockEntry)                                \
   V(BoundsCheck)                               \
@@ skipping 494 matching lines @@
     kIsArguments,
     kTruncatingToInt32,
     kIsDead,
     // Instructions that are allowed to produce full range unsigned integer
     // values are marked with kUint32 flag. If arithmetic shift or a load from
     // EXTERNAL_UNSIGNED_INT_ELEMENTS array is not marked with this flag
     // it will deoptimize if result does not fit into signed integer range.
     // HGraph::ComputeSafeUint32Operations is responsible for setting this
     // flag.
     kUint32,
-    kLastFlag = kUint32
+    // SSI construction sets this flag while processing instructions.
+    // This means that a new SSI definition is known to dominate every
+    // instruction in the same basic block that has this flag still unset.
+    kProcessedBySsi,
+    kLastFlag = kProcessedBySsi
   };
 
   STATIC_ASSERT(kLastFlag < kBitsPerInt);
 
   static const int kChangesToDependsFlagsLeftShift = 1;
 
   static GVNFlag ChangesFlagFromInt(int x) {
     return static_cast<GVNFlag>(x * 2);
   }
   static GVNFlag DependsOnFlagFromInt(int x) {
@@ skipping 20 matching lines @@
     HYDROGEN_CONCRETE_INSTRUCTION_LIST(DECLARE_PREDICATE)
   #undef DECLARE_PREDICATE
     bool IsPhi() const { return opcode() == kPhi; }
 
   // Declare virtual predicates for abstract HInstruction or HValue
   #define DECLARE_PREDICATE(type) \
     virtual bool Is##type() const { return false; }
     HYDROGEN_ABSTRACT_INSTRUCTION_LIST(DECLARE_PREDICATE)
   #undef DECLARE_PREDICATE
 
+  virtual void BuildSsi() { }
+
   HValue() : block_(NULL),
              id_(kNoNumber),
              type_(HType::Tagged()),
              use_list_(NULL),
              range_(NULL),
              flags_(0) {}
   virtual ~HValue() {}
 
   HBasicBlock* block() const { return block_; }
   void SetBlock(HBasicBlock* block);
@@ skipping 18 matching lines @@
   virtual void AssumeRepresentation(Representation r);
 
   virtual bool IsConvertibleToInteger() const { return true; }
 
   HType type() const { return type_; }
   void set_type(HType new_type) {
     ASSERT(new_type.IsSubtypeOf(type_));
     type_ = new_type;
   }
 
+  virtual HValue* ValueBeforeSsi() { return this; }
+
   // An operation needs to override this function iff:
   //   1) it can produce an int32 output.
   //   2) the true value of its output can potentially be minus zero.
   // The implementation must set a flag so that it bails out in the case where
   // it would otherwise output what should be a minus zero as an int32 zero.
   // If the operation also exists in a form that takes int32 and outputs int32
   // then the operation should return its input value so that we can propagate
   // back.  There are three operations that need to propagate back to more than
   // one input.  They are phi and binary div and mul.  They always return NULL
   // and expect the caller to take care of things.
@@ skipping 2158 matching lines @@
 
   HValue* receiver() { return OperandAt(0); }
   HValue* function() { return OperandAt(1); }
 
   virtual HValue* Canonicalize();
 
   DECLARE_CONCRETE_INSTRUCTION(WrapReceiver)
 };
 
 
+class HSsiDefinition : public HUnaryOperation {
+ public:
+  enum ValueInfoRelation { NONE, NE, GT, GE, EQ, LE, LT, IF_TAGGED_IS_SMI};
+  static const char* RelationName(ValueInfoRelation r) {
+    switch (r) {
+      case NE:
+        return "NE";
+      case GT:
+        return "GT";
+      case GE:
+        return "GE";
+      case EQ:
+        return "EQ";
+      case LE:
+        return "LE";
+      case LT:
+        return "LT";
+      case IF_TAGGED_IS_SMI:
+        return "IF_TAGGED_IS_SMI";
+      case NONE:
+        return "NONE";
+      default:
+        UNREACHABLE();
+        return "UNREACHABLE";
+    }
+  }
+
+  static HSsiDefinition* New(HValue* previous_definition,
+                             HInstruction* insertion_point,
+                             ValueInfoRelation relation,
+                             HValue* constraint,
+                             int delta = 0);
+
+  HValue* previous_definition() { return OperandAt(0); }
+
+  virtual HValue* ValueBeforeSsi() { return value_before_ssi_; }
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return ValueBeforeSsi()->RequiredInputRepresentation(index);
+  }
+
+  virtual void PrintDataTo(StringStream* stream);
+
+  HValue* constraint() { return constraint_; }
+  ValueInfoRelation relation() { return relation_; }
+  int delta() { return delta_; }
+
+  DECLARE_CONCRETE_INSTRUCTION(SsiDefinition)
+
+ protected:
+  virtual bool DataEquals(HValue* other) {
+    return DataEquals(ValueBeforeSsi());
+  }
+
+ private:
+  explicit HSsiDefinition(HValue* previous_definition,
+                          HInstruction* insertion_point,
+                          ValueInfoRelation relation,
+                          HValue* constraint,
+                          int delta);
+
+  HValue* value_before_ssi_;
+  ValueInfoRelation relation_;
+  HValue* constraint_;
+  int delta_;
+};
+
+
 class HApplyArguments: public HTemplateInstruction<4> {
  public:
   HApplyArguments(HValue* function,
                   HValue* receiver,
                   HValue* length,
                   HValue* elements) {
     set_representation(Representation::Tagged());
     SetOperandAt(0, function);
     SetOperandAt(1, receiver);
     SetOperandAt(2, length);
@@ skipping 131 matching lines @@
       return Representation::Tagged();
     }
     return Representation::Integer32();
   }
   virtual Representation observed_input_representation(int index) {
     return Representation::Integer32();
   }
 
   virtual void PrintDataTo(StringStream* stream);
 
+  virtual void BuildSsi();
+
   HValue* index() { return OperandAt(0); }
   HValue* length() { return OperandAt(1); }
 
   DECLARE_CONCRETE_INSTRUCTION(BoundsCheck)
 
  protected:
   virtual bool DataEquals(HValue* other) { return true; }
   BoundsCheckKeyMode key_mode_;
 };
 
@@ skipping 2443 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_