[heap] Remove unused code write barrier

Write barrier was only used in Factory::CopyCode for the
InterpreterEntryTrampolineForProfiling. This was removed in
in https://crrev.com/c/3811287.

Change-Id: I4cd0863fc2629d2d564af6a269e722d1a9e128f0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3843141
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82609}

src/heap/heap-write-barrier-inl.h

@@ -27,7 +27,6 @@ V8_EXPORT_PRIVATE void Heap_CombinedGenerationalAndSharedBarrierSlow(
     HeapObject object, Address slot, HeapObject value);
 V8_EXPORT_PRIVATE void Heap_CombinedGenerationalAndSharedEphemeronBarrierSlow(
     EphemeronHashTable table, Address slot, HeapObject value);
-V8_EXPORT_PRIVATE void Heap_WriteBarrierForCodeSlow(Code host);
 
 V8_EXPORT_PRIVATE void Heap_GenerationalBarrierForCodeSlow(Code host,
                                                            RelocInfo* rinfo,
@@ -152,10 +151,6 @@ inline void WriteBarrierForCode(Code host, RelocInfo* rinfo, HeapObject value,
   WriteBarrier::Marking(host, rinfo, value);
 }
 
-inline void WriteBarrierForCode(Code host) {
-  Heap_WriteBarrierForCodeSlow(host);
-}
-
 inline void CombinedWriteBarrier(HeapObject host, ObjectSlot slot, Object value,
                                  WriteBarrierMode mode) {
   if (mode == SKIP_WRITE_BARRIER) {

src/heap/heap-write-barrier.h

@@ -33,7 +33,6 @@ void WriteBarrierForCode(Code host, RelocInfo* rinfo, Object value,
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 void WriteBarrierForCode(Code host, RelocInfo* rinfo, HeapObject value,
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
-void WriteBarrierForCode(Code host);
 
 void CombinedWriteBarrier(HeapObject object, ObjectSlot slot, Object value,
                           WriteBarrierMode mode);

src/heap/heap.cc

@@ -146,10 +146,6 @@ void Heap_CombinedGenerationalAndSharedEphemeronBarrierSlow(
   Heap::CombinedGenerationalAndSharedEphemeronBarrierSlow(table, slot, value);
 }
 
-void Heap_WriteBarrierForCodeSlow(Code host) {
-  Heap::WriteBarrierForCodeSlow(host);
-}
-
 void Heap_GenerationalBarrierForCodeSlow(Code host, RelocInfo* rinfo,
                                          HeapObject object) {
   Heap::GenerationalBarrierForCodeSlow(host, rinfo, object);
@@ -7222,48 +7218,6 @@ CodeLookupResult Heap::GcSafeFindCodeForInnerPointerForPrinting(
   return {};
 }
 
-class CodeObjectVisitor : public ObjectVisitorWithCageBases {
- public:
-  explicit CodeObjectVisitor(Isolate* isolate)
-      : ObjectVisitorWithCageBases(isolate) {}
-
-  void VisitCodePointer(HeapObject host, CodeObjectSlot slot) override {
-    UNREACHABLE();
-  }
-  void VisitCodeTarget(Code host, RelocInfo* rinfo) override {
-#ifdef ENABLE_SLOW_DCHECKS
-    DCHECK(RelocInfo::IsCodeTargetMode(rinfo->rmode()));
-    Code target_object =
-        Code::GetCodeFromTargetAddress(rinfo->target_address());
-    DCHECK(!WriteBarrier::IsRequired(host, target_object));
-#endif
-  }
-
-  void VisitEmbeddedPointer(Code host, RelocInfo* rinfo) override {
-    HeapObject target_object = rinfo->target_object(cage_base());
-    WriteBarrierForCode(host, rinfo, target_object);
-  }
-  void VisitPointers(HeapObject host, MaybeObjectSlot start,
-                     MaybeObjectSlot end) override {
-    UNREACHABLE();
-  }
-  void VisitPointers(HeapObject host, ObjectSlot start,
-                     ObjectSlot end) override {
-    for (ObjectSlot slot = start; slot < end; ++slot) {
-      Object object = slot.Relaxed_Load(cage_base());
-      CombinedWriteBarrier(host, slot, object, UPDATE_WRITE_BARRIER);
-    }
-  }
-};
-
-void Heap::WriteBarrierForCodeSlow(Code code) {
-  Isolate* isolate = GetIsolateFromWritableObject(code);
-  CombinedWriteBarrier(code, code.map_slot(), code.map(isolate),
-                       UPDATE_WRITE_BARRIER);
-  CodeObjectVisitor visitor(isolate);
-  Code::BodyDescriptor::IterateBody(code.map(isolate), code, &visitor);
-}
-
 void Heap::CombinedGenerationalAndSharedBarrierSlow(HeapObject object,
                                                     Address slot,
                                                     HeapObject value) {

src/heap/heap.h

@@ -498,8 +498,6 @@ class Heap {
   V8_EXPORT_PRIVATE void WriteBarrierForRange(HeapObject object, TSlot start,
                                               TSlot end);
 
-  V8_EXPORT_PRIVATE static void WriteBarrierForCodeSlow(Code host);
-
   // Implements slow path of both generational & shared heap barrier.
   V8_EXPORT_PRIVATE static void CombinedGenerationalAndSharedBarrierSlow(
       HeapObject object, Address slot, HeapObject value);