[cleanup] Reduce code size in heap snapshot generator.

This reduces the usage of macros and shrinks the binary size (by 4 KiB).

Bug: v8:8238
Change-Id: Ic689f8ce7dabe481125fcdb74a265155431317b6
Reviewed-on: https://chromium-review.googlesource.com/1253605Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56316}

src/profiler/heap-snapshot-generator.cc

@@ -1040,6 +1040,22 @@ void V8HeapExplorer::ExtractEphemeronHashTableReferences(
   }
 }
 
+// These static arrays are used to prevent excessive code-size in
+// ExtractContextReferences below, which would happen if we called
+// SetInternalReference for every native context field in a macro.
+static const int native_context_indices[] = {
+#define CONTEXT_FIELD_INDEX(index, ...) Context::index,
+    NATIVE_CONTEXT_FIELDS(CONTEXT_FIELD_INDEX)
+#undef CONTEXT_FIELD_INDEX
+};
+static const char* native_context_names[] = {
+#define CONTEXT_FIELD_NAME(index, _, name) #name,
+    NATIVE_CONTEXT_FIELDS(CONTEXT_FIELD_NAME)
+#undef CONTEXT_FIELD_NAME
+};
+STATIC_ASSERT(arraysize(native_context_indices) ==
+              arraysize(native_context_names));
+
 void V8HeapExplorer::ExtractContextReferences(int entry, Context* context) {
   if (!context->IsNativeContext() && context->is_declaration_context()) {
     ScopeInfo* scope_info = context->scope_info();
@@ -1061,26 +1077,38 @@ void V8HeapExplorer::ExtractContextReferences(int entry, Context* context) {
     }
   }
 
-#define EXTRACT_CONTEXT_FIELD(index, type, name) \
-  if (Context::index < Context::FIRST_WEAK_SLOT || \
-      Context::index == Context::MAP_CACHE_INDEX) { \
-    SetInternalReference(context, entry, #name, context->get(Context::index), \
-        FixedArray::OffsetOfElementAt(Context::index)); \
-  } else { \
-    SetWeakReference(context, entry, #name, context->get(Context::index), \
-        FixedArray::OffsetOfElementAt(Context::index)); \
-  }
-  EXTRACT_CONTEXT_FIELD(SCOPE_INFO_INDEX, ScopeInfo, scope_info);
-  EXTRACT_CONTEXT_FIELD(PREVIOUS_INDEX, Context, previous);
-  EXTRACT_CONTEXT_FIELD(EXTENSION_INDEX, HeapObject, extension);
-  EXTRACT_CONTEXT_FIELD(NATIVE_CONTEXT_INDEX, Context, native_context);
+  SetInternalReference(
+      context, entry, "scope_info", context->get(Context::SCOPE_INFO_INDEX),
+      FixedArray::OffsetOfElementAt(Context::SCOPE_INFO_INDEX));
+  SetInternalReference(context, entry, "previous",
+                       context->get(Context::PREVIOUS_INDEX),
+                       FixedArray::OffsetOfElementAt(Context::PREVIOUS_INDEX));
+  SetInternalReference(context, entry, "extension",
+                       context->get(Context::EXTENSION_INDEX),
+                       FixedArray::OffsetOfElementAt(Context::EXTENSION_INDEX));
+  SetInternalReference(
+      context, entry, "native_context",
+      context->get(Context::NATIVE_CONTEXT_INDEX),
+      FixedArray::OffsetOfElementAt(Context::NATIVE_CONTEXT_INDEX));
+
   if (context->IsNativeContext()) {
     TagObject(context->normalized_map_cache(), "(context norm. map cache)");
     TagObject(context->embedder_data(), "(context data)");
-    NATIVE_CONTEXT_FIELDS(EXTRACT_CONTEXT_FIELD)
-    EXTRACT_CONTEXT_FIELD(OPTIMIZED_CODE_LIST, unused, optimized_code_list);
-    EXTRACT_CONTEXT_FIELD(DEOPTIMIZED_CODE_LIST, unused, deoptimized_code_list);
-#undef EXTRACT_CONTEXT_FIELD
+    for (size_t i = 0; i < arraysize(native_context_indices); i++) {
+      int index = native_context_indices[i];
+      const char* name = native_context_names[i];
+      SetInternalReference(context, entry, name, context->get(index),
+                           FixedArray::OffsetOfElementAt(index));
+    }
+
+    SetWeakReference(
+        context, entry, "optimized_code_list",
+        context->get(Context::OPTIMIZED_CODE_LIST),
+        FixedArray::OffsetOfElementAt(Context::OPTIMIZED_CODE_LIST));
+    SetWeakReference(
+        context, entry, "deoptimized_code_list",
+        context->get(Context::DEOPTIMIZED_CODE_LIST),
+        FixedArray::OffsetOfElementAt(Context::DEOPTIMIZED_CODE_LIST));
     STATIC_ASSERT(Context::OPTIMIZED_CODE_LIST == Context::FIRST_WEAK_SLOT);
     STATIC_ASSERT(Context::NEXT_CONTEXT_LINK + 1 ==
                   Context::NATIVE_CONTEXT_SLOTS);
@@ -1089,7 +1117,6 @@ void V8HeapExplorer::ExtractContextReferences(int entry, Context* context) {
   }
 }
 
-
 void V8HeapExplorer::ExtractMapReferences(int entry, Map* map) {
   MaybeObject* maybe_raw_transitions_or_prototype_info = map->raw_transitions();
   HeapObject* raw_transitions_or_prototype_info;