From ee164ffe3ddacdf79cd5d2bb536f3ae66c58db70 Mon Sep 17 00:00:00 2001
From: "hpayer@chromium.org"
 <hpayer@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Thu, 22 Nov 2012 07:05:20 +0000
Subject: [PATCH] Use slot instead of value in the write barrier to record
 write from code.

BUG=

Review URL: https://codereview.chromium.org/11412096

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13029 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/arm/code-stubs-arm.cc   | 7 +------
 src/ia32/code-stubs-ia32.cc | 8 +-------
 src/incremental-marking.cc  | 4 ++--
 src/incremental-marking.h   | 2 +-
 src/mips/code-stubs-mips.cc | 7 +------
 src/x64/code-stubs-x64.cc   | 9 ++-------
 6 files changed, 8 insertions(+), 29 deletions(-)

diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 2c2589cf3c..5374b36b48 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -7381,12 +7381,7 @@ void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm, Mode mode) {
   ASSERT(!address.is(r0));
   __ Move(address, regs_.address());
   __ Move(r0, regs_.object());
-  if (mode == INCREMENTAL_COMPACTION) {
-    __ Move(r1, address);
-  } else {
-    ASSERT(mode == INCREMENTAL);
-    __ ldr(r1, MemOperand(address, 0));
-  }
+  __ Move(r1, address);
   __ mov(r2, Operand(ExternalReference::isolate_address()));
 
   AllowExternalCallThatCantCauseGC scope(masm);
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 42086c8fc8..fa3e1a88bb 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -7225,13 +7225,7 @@ void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm, Mode mode) {
   int argument_count = 3;
   __ PrepareCallCFunction(argument_count, regs_.scratch0());
   __ mov(Operand(esp, 0 * kPointerSize), regs_.object());
-  if (mode == INCREMENTAL_COMPACTION) {
-    __ mov(Operand(esp, 1 * kPointerSize), regs_.address());  // Slot.
-  } else {
-    ASSERT(mode == INCREMENTAL);
-    __ mov(regs_.scratch0(), Operand(regs_.address(), 0));
-    __ mov(Operand(esp, 1 * kPointerSize), regs_.scratch0());  // Value.
-  }
+  __ mov(Operand(esp, 1 * kPointerSize), regs_.address());  // Slot.
   __ mov(Operand(esp, 2 * kPointerSize),
          Immediate(ExternalReference::isolate_address()));
 
diff --git a/src/incremental-marking.cc b/src/incremental-marking.cc
index e9fd74c0d1..e420d28521 100644
--- a/src/incremental-marking.cc
+++ b/src/incremental-marking.cc
@@ -78,7 +78,7 @@ void IncrementalMarking::RecordWriteSlow(HeapObject* obj,
 
 
 void IncrementalMarking::RecordWriteFromCode(HeapObject* obj,
-                                             Object* value,
+                                             Object** slot,
                                              Isolate* isolate) {
   ASSERT(obj->IsHeapObject());
   IncrementalMarking* marking = isolate->heap()->incremental_marking();
@@ -94,7 +94,7 @@ void IncrementalMarking::RecordWriteFromCode(HeapObject* obj,
         MemoryChunk::kWriteBarrierCounterGranularity);
   }
 
-  marking->RecordWrite(obj, NULL, value);
+  marking->RecordWrite(obj, slot, *slot);
 }
 
 
diff --git a/src/incremental-marking.h b/src/incremental-marking.h
index 77d54bed4b..fc5a978cc4 100644
--- a/src/incremental-marking.h
+++ b/src/incremental-marking.h
@@ -127,7 +127,7 @@ class IncrementalMarking {
   }
 
   static void RecordWriteFromCode(HeapObject* obj,
-                                  Object* value,
+                                  Object** slot,
                                   Isolate* isolate);
 
   static void RecordWriteForEvacuationFromCode(HeapObject* obj,
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 2897878cbf..0e4d37b2fe 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -7555,12 +7555,7 @@ void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm, Mode mode) {
   ASSERT(!address.is(a0));
   __ Move(address, regs_.address());
   __ Move(a0, regs_.object());
-  if (mode == INCREMENTAL_COMPACTION) {
-    __ Move(a1, address);
-  } else {
-    ASSERT(mode == INCREMENTAL);
-    __ lw(a1, MemOperand(address, 0));
-  }
+  __ Move(a1, address);
   __ li(a2, Operand(ExternalReference::isolate_address()));
 
   AllowExternalCallThatCantCauseGC scope(masm);
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index 6d6d3e9c06..c529eb4da5 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -6214,13 +6214,8 @@ void RecordWriteStub::InformIncrementalMarker(MacroAssembler* masm, Mode mode) {
   ASSERT(!address.is(arg1));
   __ Move(address, regs_.address());
   __ Move(arg1, regs_.object());
-  if (mode == INCREMENTAL_COMPACTION) {
-    // TODO(gc) Can we just set address arg2 in the beginning?
-    __ Move(arg2, address);
-  } else {
-    ASSERT(mode == INCREMENTAL);
-    __ movq(arg2, Operand(address, 0));
-  }
+  // TODO(gc) Can we just set address arg2 in the beginning?
+  __ Move(arg2, address);
   __ LoadAddress(arg3, ExternalReference::isolate_address());
   int argument_count = 3;