[heap, deoptimizer] Use proper right trim instead of manually trimming

Failing to do so results in out-of-date marking information, because live bytes
is not properly adjusted.

This CL adds support for right trimming ByteArray and properly DCHECKs that we
do not left trim  ByteArray (as we already do for FixedTypedArrayBase).

BUG=

Review URL: https://codereview.chromium.org/1577263003

Cr-Commit-Position: refs/heads/master@{#33252}

src/heap/heap.cc

@@ -3117,6 +3117,7 @@ void Heap::AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode) {
 FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object,
                                          int elements_to_trim) {
   DCHECK(!object->IsFixedTypedArrayBase());
+  DCHECK(!object->IsByteArray());
   const int element_size = object->IsFixedArray() ? kPointerSize : kDoubleSize;
   const int bytes_to_trim = elements_to_trim * element_size;
   Map* map = object->map();
@@ -3173,7 +3174,8 @@ template void Heap::RightTrimFixedArray<Heap::CONCURRENT_TO_SWEEPER>(
 template<Heap::InvocationMode mode>
 void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) {
   const int len = object->length();
-  DCHECK(elements_to_trim < len);
+  DCHECK_LE(elements_to_trim, len);
+  DCHECK_GE(elements_to_trim, 0);
 
   int bytes_to_trim;
   if (object->IsFixedTypedArrayBase()) {
@@ -3181,12 +3183,17 @@ void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) {
     bytes_to_trim =
         FixedTypedArrayBase::TypedArraySize(type, len) -
         FixedTypedArrayBase::TypedArraySize(type, len - elements_to_trim);
+  } else if (object->IsByteArray()) {
+    int new_size = ByteArray::SizeFor(len - elements_to_trim);
+    bytes_to_trim = ByteArray::SizeFor(len) - new_size;
+    DCHECK_GE(bytes_to_trim, 0);
   } else {
     const int element_size =
         object->IsFixedArray() ? kPointerSize : kDoubleSize;
     bytes_to_trim = elements_to_trim * element_size;
   }
 
+
   // For now this trick is only applied to objects in new and paged space.
   DCHECK(object->map() != fixed_cow_array_map());
 

src/ia32/deoptimizer-ia32.cc

@@ -157,18 +157,15 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   }
 
   // Move the relocation info to the beginning of the byte array.
-  int new_reloc_size = reloc_end_address - reloc_info_writer.pos();
-  MemMove(code->relocation_start(), reloc_info_writer.pos(), new_reloc_size);
-
-  // The relocation info is in place, update the size.
-  reloc_info->set_length(new_reloc_size);
-
-  // Handle the junk part after the new relocation info. We will create
-  // a non-live object in the extra space at the end of the former reloc info.
-  Address junk_address = reloc_info->address() + reloc_info->Size();
-  DCHECK(junk_address <= reloc_end_address);
-  isolate->heap()->CreateFillerObjectAt(junk_address,
-                                        reloc_end_address - junk_address);
+  const int new_reloc_length = reloc_end_address - reloc_info_writer.pos();
+  MemMove(code->relocation_start(), reloc_info_writer.pos(), new_reloc_length);
+
+  // Right trim the relocation info to free up remaining space.
+  const int delta = reloc_info->length() - new_reloc_length;
+  if (delta > 0) {
+    isolate->heap()->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(
+        reloc_info, delta);
+  }
 }
 
 

src/x87/deoptimizer-x87.cc

@@ -157,18 +157,15 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
   }
 
   // Move the relocation info to the beginning of the byte array.
-  int new_reloc_size = reloc_end_address - reloc_info_writer.pos();
-  MemMove(code->relocation_start(), reloc_info_writer.pos(), new_reloc_size);
-
-  // The relocation info is in place, update the size.
-  reloc_info->set_length(new_reloc_size);
-
-  // Handle the junk part after the new relocation info. We will create
-  // a non-live object in the extra space at the end of the former reloc info.
-  Address junk_address = reloc_info->address() + reloc_info->Size();
-  DCHECK(junk_address <= reloc_end_address);
-  isolate->heap()->CreateFillerObjectAt(junk_address,
-                                        reloc_end_address - junk_address);
+  const int new_reloc_length = reloc_end_address - reloc_info_writer.pos();
+  MemMove(code->relocation_start(), reloc_info_writer.pos(), new_reloc_length);
+
+  // Right trim the relocation info to free up remaining space.
+  const int delta = reloc_info->length() - new_reloc_length;
+  if (delta > 0) {
+    isolate->heap()->RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(
+        reloc_info, delta);
+  }
 }