Remove all leftovers of store buffer

V8's write barrier doesn't use a store buffer anymore but inserts
directly into the remembered set. However, there were still some
comments/method definitions left.

Bug: v8:9454
Change-Id: Ic3bc3394750f1d4989027e07dbc9201c3f484ccd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3270536Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77814}

src/builtins/builtins-internal-gen.cc

@@ -248,7 +248,8 @@ class WriteBarrierCodeStubAssembler : public CodeStubAssembler {
 
   void GenerationalWriteBarrier(SaveFPRegsMode fp_mode) {
     Label incremental_wb(this), test_old_to_young_flags(this),
-        store_buffer_exit(this), store_buffer_incremental_wb(this), next(this);
+        remembered_set_only(this), remembered_set_and_incremental_wb(this),
+        next(this);
 
     // When incremental marking is not on, we skip cross generation pointer
     // checking here, because there are checks for
@@ -258,7 +259,7 @@ class WriteBarrierCodeStubAssembler : public CodeStubAssembler {
     // stub, which serves as the cross generation checking.
     auto slot =
         UncheckedParameter<IntPtrT>(WriteBarrierDescriptor::kSlotAddress);
-    Branch(IsMarking(), &test_old_to_young_flags, &store_buffer_exit);
+    Branch(IsMarking(), &test_old_to_young_flags, &remembered_set_only);
 
     BIND(&test_old_to_young_flags);
     {
@@ -275,10 +276,11 @@ class WriteBarrierCodeStubAssembler : public CodeStubAssembler {
           UncheckedParameter<Object>(WriteBarrierDescriptor::kObject));
       TNode<BoolT> object_is_young =
           IsPageFlagSet(object, MemoryChunk::kIsInYoungGenerationMask);
-      Branch(object_is_young, &incremental_wb, &store_buffer_incremental_wb);
+      Branch(object_is_young, &incremental_wb,
+             &remembered_set_and_incremental_wb);
     }
 
-    BIND(&store_buffer_exit);
+    BIND(&remembered_set_only);
     {
       TNode<IntPtrT> object = BitcastTaggedToWord(
           UncheckedParameter<Object>(WriteBarrierDescriptor::kObject));
@@ -286,7 +288,7 @@ class WriteBarrierCodeStubAssembler : public CodeStubAssembler {
       Goto(&next);
     }
 
-    BIND(&store_buffer_incremental_wb);
+    BIND(&remembered_set_and_incremental_wb);
     {
       TNode<IntPtrT> object = BitcastTaggedToWord(
           UncheckedParameter<Object>(WriteBarrierDescriptor::kObject));

src/builtins/promise-abstract-operations.tq

@@ -113,7 +113,7 @@ transitioning macro MorphAndEnqueuePromiseReaction(implicit context: Context)(
 
   // Morph {current} from a PromiseReaction into a PromiseReactionJobTask
   // and schedule that on the microtask queue. We try to minimize the number
-  // of stores here to avoid screwing up the store buffer.
+  // of stores here to avoid write barrier overhead.
   static_assert(
       kPromiseReactionSize ==
       kPromiseReactionJobTaskSizeOfAllPromiseReactionJobTasks);

src/codegen/ia32/macro-assembler-ia32.cc

@@ -326,7 +326,7 @@ int TurboAssembler::RequiredStackSizeForCallerSaved(SaveFPRegsMode fp_mode,
 int TurboAssembler::PushCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
                                     Register exclusion2, Register exclusion3) {
   ASM_CODE_COMMENT(this);
-  // We don't allow a GC during a store buffer overflow so there is no need to
+  // We don't allow a GC in a write barrier slow path so there is no need to
   // store the registers in any particular way, but we do have to store and
   // restore them.
   int bytes = 0;

src/codegen/x64/macro-assembler-x64.cc

@@ -819,7 +819,7 @@ int TurboAssembler::RequiredStackSizeForCallerSaved(SaveFPRegsMode fp_mode,
 int TurboAssembler::PushCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
                                     Register exclusion2, Register exclusion3) {
   ASM_CODE_COMMENT(this);
-  // We don't allow a GC during a store buffer overflow so there is no need to
+  // We don't allow a GC in a write barrier slow path so there is no need to
   // store the registers in any particular way, but we do have to store and
   // restore them.
   int bytes = 0;

src/heap/heap.h

@@ -1062,7 +1062,7 @@ class Heap {
   void IterateStackRoots(RootVisitor* v);
 
   // ===========================================================================
-  // Store buffer API. =========================================================
+  // Remembered set API. =======================================================
   // ===========================================================================
 
   // Used for query incremental marking status in generated code.
@@ -1072,10 +1072,6 @@ class Heap {
 
   void SetIsMarkingFlag(uint8_t flag) { is_marking_flag_ = flag; }
 
-  V8_EXPORT_PRIVATE Address* store_buffer_top_address();
-  static intptr_t store_buffer_mask_constant();
-  static Address store_buffer_overflow_function_address();
-
   void ClearRecordedSlot(HeapObject object, ObjectSlot slot);
   void ClearRecordedSlotRange(Address start, Address end);
   static int InsertIntoRememberedSetFromCode(MemoryChunk* chunk, Address slot);

src/heap/spaces.h

@@ -61,8 +61,7 @@ class SemiSpace;
 // collection. The large object space is paged. Pages in large object space
 // may be larger than the page size.
 //
-// A store-buffer based write barrier is used to keep track of intergenerational
-// references.  See heap/store-buffer.h.
+// A remembered set is used to keep track of intergenerational references.
 //
 // During scavenges and mark-sweep collections we sometimes (after a store
 // buffer overflow) iterate intergenerational pointers without decoding heap

src/logging/counters-definitions.h

@@ -303,9 +303,7 @@ namespace internal {
   SC(contexts_created_by_snapshot, V8.ContextsCreatedBySnapshot)   \
   /* Number of code objects found from pc. */                      \
   SC(pc_to_code, V8.PcToCode)                                      \
-  SC(pc_to_code_cached, V8.PcToCodeCached)                         \
-  /* The store-buffer implementation of the write barrier. */      \
-  SC(store_buffer_overflows, V8.StoreBufferOverflows)
+  SC(pc_to_code_cached, V8.PcToCodeCached)
 
 #define STATS_COUNTER_LIST_2(SC)                                               \
   /* Amount of (JS) compiled code. */                                          \

tools/eval_gc_time.sh

@@ -92,7 +92,6 @@ INTERESTING_OLD_GEN_KEYS="\
   clear.global_handles \
   clear.maps \
   clear.slots_buffer \
-  clear.store_buffer \
   clear.string_table \
   clear.weak_collections \
   clear.weak_lists \