Revert "[heap] Register executable MemoryChunks."

This reverts commit e97daee2.

Bug: chromium:803046,chromium:774108,v8:6792
Change-Id: I15ee3c109b22fa9fe9658c93bd73cb4454310df5
Reviewed-on: https://chromium-review.googlesource.com/870837Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50664}

src/heap/heap-inl.h

@@ -626,7 +626,6 @@ CodeSpaceMemoryModificationScope::CodeSpaceMemoryModificationScope(Heap* heap)
     LargePage* page = heap_->lo_space()->first_page();
     while (page != nullptr) {
       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
-        CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
         page->SetReadAndWritable();
       }
       page = page->next_page();
@@ -641,7 +640,6 @@ CodeSpaceMemoryModificationScope::~CodeSpaceMemoryModificationScope() {
     LargePage* page = heap_->lo_space()->first_page();
     while (page != nullptr) {
       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
-        CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
         page->SetReadAndExecutable();
       }
       page = page->next_page();
@@ -658,14 +656,12 @@ CodePageMemoryModificationScope::CodePageMemoryModificationScope(
     DCHECK(chunk_->owner()->identity() == CODE_SPACE ||
            (chunk_->owner()->identity() == LO_SPACE &&
             chunk_->IsFlagSet(MemoryChunk::IS_EXECUTABLE)));
-    CHECK(chunk_->heap()->memory_allocator()->IsMemoryChunkExecutable(chunk_));
     chunk_->SetReadAndWritable();
   }
 }
 
 CodePageMemoryModificationScope::~CodePageMemoryModificationScope() {
   if (scope_active_) {
-    CHECK(chunk_->heap()->memory_allocator()->IsMemoryChunkExecutable(chunk_));
     chunk_->SetReadAndExecutable();
   }
 }

src/heap/spaces.cc

@@ -826,13 +826,8 @@ MemoryChunk* MemoryAllocator::AllocateChunk(size_t reserve_area_size,
                          owner);
   }
 
-  MemoryChunk* chunk =
-      MemoryChunk::Initialize(heap, base, chunk_size, area_start, area_end,
-                              executable, owner, &reservation);
-
-  if (executable) RegisterExecutableMemoryChunk(chunk);
-
-  return chunk;
+  return MemoryChunk::Initialize(heap, base, chunk_size, area_start, area_end,
+                                 executable, owner, &reservation);
 }
 
 void Page::ResetAllocatedBytes() { allocated_bytes_ = area_size(); }
@@ -975,8 +970,6 @@ void MemoryAllocator::PreFreeMemory(MemoryChunk* chunk) {
   }
 
   chunk->SetFlag(MemoryChunk::PRE_FREED);
-
-  if (chunk->executable()) UnregisterExecutableMemoryChunk(chunk);
 }
 
 
@@ -1729,7 +1722,6 @@ void PagedSpace::ReleasePage(Page* page) {
 void PagedSpace::SetReadAndExecutable() {
   DCHECK(identity() == CODE_SPACE);
   for (Page* page : *this) {
-    CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
     page->SetReadAndExecutable();
   }
 }
@@ -1737,7 +1729,6 @@ void PagedSpace::SetReadAndExecutable() {
 void PagedSpace::SetReadAndWritable() {
   DCHECK(identity() == CODE_SPACE);
   for (Page* page : *this) {
-    CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
     page->SetReadAndWritable();
   }
 }

src/heap/spaces.h

@@ -1359,12 +1359,6 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
   // and false otherwise.
   bool CommitBlock(Address start, size_t size, Executability executable);
 
-  // Checks if an allocated MemoryChunk was intended to be used for executable
-  // memory.
-  bool IsMemoryChunkExecutable(MemoryChunk* chunk) {
-    return executable_memory_.find(chunk) != executable_memory_.end();
-  }
-
   // Uncommit a contiguous block of memory [start..(start+size)[.
   // start is not nullptr, the size is greater than zero, and the
   // block is contained in the initial chunk.  Returns true if it succeeded
@@ -1415,17 +1409,6 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
     } while ((high > ptr) && !highest_ever_allocated_.TrySetValue(ptr, high));
   }
 
-  void RegisterExecutableMemoryChunk(MemoryChunk* chunk) {
-    DCHECK(chunk->IsFlagSet(MemoryChunk::IS_EXECUTABLE));
-    DCHECK_EQ(executable_memory_.find(chunk), executable_memory_.end());
-    executable_memory_.insert(chunk);
-  }
-
-  void UnregisterExecutableMemoryChunk(MemoryChunk* chunk) {
-    DCHECK_NE(executable_memory_.find(chunk), executable_memory_.end());
-    executable_memory_.erase(chunk);
-  }
-
   Isolate* isolate_;
   CodeRange* code_range_;
 
@@ -1448,9 +1431,6 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
   VirtualMemory last_chunk_;
   Unmapper unmapper_;
 
-  // Data structure to remember allocated executable memory chunks.
-  std::unordered_set<MemoryChunk*> executable_memory_;
-
   friend class heap::TestCodeRangeScope;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryAllocator);