[heap] Make {Factory::CopyCode} use finer scope.

This makes the above factory function use a fine-grained scope when
unlocking code space for modification. It now uses a cumulative per-page
scope that collects only those memory chunks that needed to be touched
during allocation.

R=ulan@chromium.org

Change-Id: I22de0fae8be507ba9d51868f668b902b3bae3d6a
Reviewed-on: https://chromium-review.googlesource.com/c/1335558Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57503}

src/compiler.cc

@@ -315,13 +315,8 @@ void InstallBytecodeArray(Handle<BytecodeArray> bytecode_array,
     return;
   }
 
-  Handle<Code> code;
-  {
-    CodeSpaceMemoryModificationScope code_allocation(isolate->heap());
-
-    code = isolate->factory()->CopyCode(
+  Handle<Code> code = isolate->factory()->CopyCode(
       BUILTIN_CODE(isolate, InterpreterEntryTrampoline));
-  }
 
   Handle<InterpreterData> interpreter_data = Handle<InterpreterData>::cast(
       isolate->factory()->NewStruct(INTERPRETER_DATA_TYPE, TENURED));

src/heap/factory.cc

@@ -2735,14 +2735,17 @@ Handle<Code> Factory::CopyCode(Handle<Code> code) {
       NewCodeDataContainer(code->code_data_container()->kind_specific_flags());
 
   Heap* heap = isolate()->heap();
+  Handle<Code> new_code;
+  {
     int obj_size = code->Size();
+    CodePageCollectionMemoryModificationScope code_allocation(heap);
     HeapObject* result = heap->AllocateRawWithRetryOrFail(obj_size, CODE_SPACE);
 
     // Copy code object.
     Address old_addr = code->address();
     Address new_addr = result->address();
     Heap::CopyBlock(new_addr, old_addr, obj_size);
-  Handle<Code> new_code(Code::cast(result), isolate());
+    new_code = handle(Code::cast(result), isolate());
 
     // Set the {CodeDataContainer}, it cannot be shared.
     new_code->set_code_data_container(*data_container);
@@ -2753,6 +2756,7 @@ Handle<Code> Factory::CopyCode(Handle<Code> code) {
     heap->incremental_marking()->ProcessBlackAllocatedObject(*new_code);
     // Record all references to embedded objects in the new code object.
     WriteBarrierForCode(*new_code);
+  }
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) new_code->ObjectVerify(isolate());