Improve write barriers in optimized code.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 9674ef182977718bb41fb4b9bbcc5550b454e0f2..b5341973166b5855b64d36bf4a531a459b6ed704 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -437,7 +437,8 @@ void MacroAssembler::RecordWriteField(
     Register dst,
     SaveFPRegsMode save_fp,
     RememberedSetAction remembered_set_action,
-    SmiCheck smi_check) {
+    SmiCheck smi_check,
+    bool value_is_in_new_space) {
   // First, check if a write barrier is even needed. The tests below
   // catch stores of Smis.
   Label done;
@@ -461,7 +462,8 @@ void MacroAssembler::RecordWriteField(
   }
 
   RecordWrite(
-      object, dst, value, save_fp, remembered_set_action, OMIT_SMI_CHECK);
+      object, dst, value, save_fp, remembered_set_action, OMIT_SMI_CHECK,
+      value_is_in_new_space);
 
   bind(&done);
 
@@ -502,6 +504,9 @@ void MacroAssembler::RecordWriteForMap(
     return;
   }
 
+  // Compute the address.
+  lea(address, FieldOperand(object, HeapObject::kMapOffset));
+
   // Count number of write barriers in generated code.
   isolate()->counters()->write_barriers_static()->Increment();
   IncrementCounter(isolate()->counters()->write_barriers_dynamic(), 1);
@@ -517,12 +522,6 @@ void MacroAssembler::RecordWriteForMap(
                       &done,
                       Label::kNear);
 
-  // Delay the initialization of |address| and |value| for the stub until it's
-  // known that the will be needed. Up until this point their values are not
-  // needed since they are embedded in the operands of instructions that need
-  // them.
-  lea(address, FieldOperand(object, HeapObject::kMapOffset));
-  mov(value, Immediate(map));
   RecordWriteStub stub(isolate(), object, value, address, OMIT_REMEMBERED_SET,
                        save_fp);
   CallStub(&stub);
@@ -544,7 +543,8 @@ void MacroAssembler::RecordWrite(Register object,
                                  Register value,
                                  SaveFPRegsMode fp_mode,
                                  RememberedSetAction remembered_set_action,
-                                 SmiCheck smi_check) {
+                                 SmiCheck smi_check,
+                                 bool value_is_in_new_space) {
   ASSERT(!object.is(value));
   ASSERT(!object.is(address));
   ASSERT(!value.is(address));
@@ -576,12 +576,14 @@ void MacroAssembler::RecordWrite(Register object,
     JumpIfSmi(value, &done, Label::kNear);
   }
 
-  CheckPageFlag(value,
-                value,  // Used as scratch.
-                MemoryChunk::kPointersToHereAreInterestingMask,
-                zero,
-                &done,
-                Label::kNear);
+  if (!value_is_in_new_space) {
+    CheckPageFlag(value,
+                  value,  // Used as scratch.
+                  MemoryChunk::kPointersToHereAreInterestingMask,
+                  zero,
+                  &done,
+                  Label::kNear);
+  }
   CheckPageFlag(object,
                 value,  // Used as scratch.
                 MemoryChunk::kPointersFromHereAreInterestingMask,