Support slots recording for compaction during incremental marking.

src/ia32/code-stubs-ia32.h

Index: src/ia32/code-stubs-ia32.h
diff --git a/src/ia32/code-stubs-ia32.h b/src/ia32/code-stubs-ia32.h
index cc6bd1675c3ed7d11a01f241c9611d5726d77f49..bc0a478a0369644ff77df7e97f1d231631ba7690 100644
--- a/src/ia32/code-stubs-ia32.h
+++ b/src/ia32/code-stubs-ia32.h
@@ -544,24 +544,27 @@ class RecordWriteStub: public CodeStub {
               value) {  // One scratch reg.
   }
 
-  static const byte kTwoByteNopInstruction = 0x3c;          // Cmpb al, #imm8.
-  static const byte kSkipNonIncrementalPartInstruction = 0xeb;  // Jmp #imm8.
-
-  static byte GetInstruction(bool enable) {
-    // Can't use ternary operator here, because gcc makes an undefined
-    // reference to a static const int.
-    if (enable) {
-      return kSkipNonIncrementalPartInstruction;
+  static const byte kTwoByteNopInstruction = 0x3c;  // Cmpb al, #imm8.
+  static const byte kTwoByteJumpInstruction = 0xeb;  // Jmp #imm8.
+
+  static const byte kFiveByteNopInstruction = 0x3d;  // Cmpl al, #imm32.

[Erik Corry, 2011/07/04 11:04:11]

You are sure it is al and not eax?

[Vyacheslav Egorov (Chromium), 2011/08/05 12:50:28]

Done.

+  static const byte kFiveByteJumpInstruction = 0xe9;  // Jmp #imm32.
+
+  static void Patch(Code* stub, bool incremental, bool compaction) {
+    ASSERT(!compaction || incremental);

[Erik Corry, 2011/07/04 11:04:11]

It would be very good to assert that the old opcode was one of the ones we
expect to see.

[Vyacheslav Egorov (Chromium), 2011/08/05 12:50:28]

Done.

+    if (incremental) {
+      if (compaction) {
+        stub->instruction_start()[0] = kTwoByteNopInstruction;
+        stub->instruction_start()[2] = kFiveByteJumpInstruction;
+      } else {
+        stub->instruction_start()[0] = kTwoByteJumpInstruction;
+      }
     } else {
-      return kTwoByteNopInstruction;
+      stub->instruction_start()[0] = kTwoByteNopInstruction;
+      stub->instruction_start()[2] = kFiveByteNopInstruction;
     }
   }
 
-  static void Patch(Code* stub, bool enable) {
-    ASSERT(*stub->instruction_start() == GetInstruction(!enable));
-    *stub->instruction_start() = GetInstruction(enable);
-  }
-
  private:
   // This is a helper class for freeing up 3 scratch registers, where the third
   // is always ecx (needed for shift operations).  The input is two registers
@@ -710,12 +713,20 @@ class RecordWriteStub: public CodeStub {
     kUpdateRememberedSetOnNoNeedToInformIncrementalMarker
   };
 
+  enum EvacuationState {
+    kWithEvacuationCandidates,
+    kWithoutEvacuationCandidates
+  };
+
   void Generate(MacroAssembler* masm);
-  void GenerateIncremental(MacroAssembler* masm);
+  void GenerateIncremental(MacroAssembler* masm,
+                           EvacuationState evacuation_state);
   void CheckNeedsToInformIncrementalMarker(
       MacroAssembler* masm,
-      OnNoNeedToInformIncrementalMarker on_no_need);
-  void InformIncrementalMarker(MacroAssembler* masm);
+      OnNoNeedToInformIncrementalMarker on_no_need,
+      EvacuationState evacuation_state);
+  void InformIncrementalMarker(MacroAssembler* masm,
+                               EvacuationState evacuation_state);
 
   Major MajorKey() { return RecordWrite; }