RFC: Switch to ast ids (instead of positions) for type feedback.

src/assembler.h

Index: src/assembler.h
diff --git a/src/assembler.h b/src/assembler.h
index 72a9b15380b88d65cfab2552115e0a2371ae5a1b..ff990309d972a466cbee545a40d552d6f1735988 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -178,10 +178,11 @@ class RelocInfo BASE_EMBEDDED {
 
   enum Mode {
     // Please note the order is important (see IsCodeTarget, IsGCRelocMode).
+    CODE_TARGET,  // Code target which is not any of the below.
+    CODE_TARGET_WITH_ID,
     CONSTRUCT_CALL,  // code target that is a call to a JavaScript constructor.
     CODE_TARGET_CONTEXT,  // Code target used for contextual loads.
     DEBUG_BREAK,  // Code target for the debugger statement.
-    CODE_TARGET,  // Code target which is not any of the above.
     EMBEDDED_OBJECT,
 
     GLOBAL_PROPERTY_CELL,
@@ -198,10 +199,13 @@ class RelocInfo BASE_EMBEDDED {
 
     // add more as needed
     // Pseudo-types
-    NUMBER_OF_MODES,  // must be no greater than 14 - see RelocInfoWriter
+    NUMBER_OF_MODES,  // must be no greater than ?? - see RelocInfoWriter

[fschneider, 2011/02/11 11:28:18]

Update comment. Maybe a STATIC_ASSERT would be better than just a comment or
normal ASSERT.

     NONE,  // never recorded
-    LAST_CODE_ENUM = CODE_TARGET,
-    LAST_GCED_ENUM = EMBEDDED_OBJECT
+    LAST_CODE_ENUM = DEBUG_BREAK,
+    LAST_GCED_ENUM = EMBEDDED_OBJECT,
+    // Modes <= LAST_COMPACT_ENUM are guaranteed to have compact
+    // encoding.
+    LAST_COMPACT_ENUM = CODE_TARGET_WITH_ID
   };
 
 
@@ -331,7 +335,8 @@ class RelocInfo BASE_EMBEDDED {
 
   static const int kCodeTargetMask = (1 << (LAST_CODE_ENUM + 1)) - 1;
   static const int kPositionMask = 1 << POSITION | 1 << STATEMENT_POSITION;
-  static const int kDebugMask = kPositionMask | 1 << COMMENT;
+  static const int kDataMask =
+      (1 << CODE_TARGET_WITH_ID) | kPositionMask | (1 << COMMENT);
   static const int kApplyMask;  // Modes affected by apply. Depends on arch.
 
  private:
@@ -350,9 +355,14 @@ class RelocInfo BASE_EMBEDDED {
 // lower addresses.
 class RelocInfoWriter BASE_EMBEDDED {
  public:
-  RelocInfoWriter() : pos_(NULL), last_pc_(NULL), last_data_(0) {}
-  RelocInfoWriter(byte* pos, byte* pc) : pos_(pos), last_pc_(pc),
-                                         last_data_(0) {}
+  RelocInfoWriter() : pos_(NULL),
+                      last_pc_(NULL),
+                      last_id_(0),
+                      last_position_(0) {}
+  RelocInfoWriter(byte* pos, byte* pc) : pos_(pos),
+                                         last_pc_(pc),
+                                         last_id_(0),
+                                         last_position_(0) {}
 
   byte* pos() const { return pos_; }
   byte* last_pc() const { return last_pc_; }
@@ -377,13 +387,15 @@ class RelocInfoWriter BASE_EMBEDDED {
   inline uint32_t WriteVariableLengthPCJump(uint32_t pc_delta);
   inline void WriteTaggedPC(uint32_t pc_delta, int tag);
   inline void WriteExtraTaggedPC(uint32_t pc_delta, int extra_tag);
+  inline void WriteExtraTaggedIntData(int data_delta, int top_tag);
   inline void WriteExtraTaggedData(intptr_t data_delta, int top_tag);
   inline void WriteTaggedData(intptr_t data_delta, int tag);
   inline void WriteExtraTag(int extra_tag, int top_tag);
 
   byte* pos_;
   byte* last_pc_;
-  intptr_t last_data_;
+  int last_id_;
+  int last_position_;
   DISALLOW_COPY_AND_ASSIGN(RelocInfoWriter);
 };
 
@@ -425,12 +437,13 @@ class RelocIterator: public Malloced {
   int GetTopTag();
   void ReadTaggedPC();
   void AdvanceReadPC();
+  void AdvanceReadId();
+  void AdvanceReadPosition();
   void AdvanceReadData();
   void AdvanceReadVariableLengthPCJump();
-  int GetPositionTypeTag();
-  void ReadTaggedData();
-
-  static RelocInfo::Mode DebugInfoModeFromTag(int tag);
+  int GetLocatableTypeTag();
+  void ReadTaggedId();
+  void ReadTaggedPosition();
 
   // If the given mode is wanted, set it in rinfo_ and return true.
   // Else return false. Used for efficiently skipping unwanted modes.
@@ -443,6 +456,8 @@ class RelocIterator: public Malloced {
   RelocInfo rinfo_;
   bool done_;
   int mode_mask_;
+  int last_id_;
+  int last_position_;
   DISALLOW_COPY_AND_ASSIGN(RelocIterator);
 };