Do not look for existing shared function info when compiling a new script.

LOG=N
BUG=chromium:502908

Review URL: https://codereview.chromium.org/1196223002

Cr-Commit-Position: refs/heads/master@{#29179}

src/compiler.cc

@@ -1078,6 +1078,8 @@ static Handle<SharedFunctionInfo> CompileToplevel(CompilationInfo* info) {
       }
     }
 
+    info->MarkAsNewScript();
+
     FunctionLiteral* lit = info->function();
     LiveEditFunctionTracker live_edit_tracker(isolate, lit);
 
@@ -1338,8 +1340,13 @@ Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
     FunctionLiteral* literal, Handle<Script> script,
     CompilationInfo* outer_info) {
   // Precondition: code has been parsed and scopes have been analyzed.
-  MaybeHandle<SharedFunctionInfo> maybe_existing =
-      script->FindSharedFunctionInfo(literal);
+  MaybeHandle<SharedFunctionInfo> maybe_existing;
+  if (outer_info->is_new_script()) {
+    // There is no existing shared function info when compiling a new script.
+    DCHECK(script->FindSharedFunctionInfo(literal).is_null());
+  } else {
+    maybe_existing = script->FindSharedFunctionInfo(literal);
+  }
   // We found an existing shared function info. If it's already compiled,
   // don't worry about compiling it, and simply return it. If it's not yet
   // compiled, continue to decide whether to eagerly compile.
@@ -1355,6 +1362,7 @@ Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
   parse_info.set_scope(literal->scope());
   parse_info.set_language_mode(literal->scope()->language_mode());
   if (outer_info->will_serialize()) info.PrepareForSerializing();
+  if (outer_info->is_new_script()) info.MarkAsNewScript();
 
   Isolate* isolate = info.isolate();
   Factory* factory = isolate->factory();

src/compiler.h

@@ -127,7 +127,8 @@ class CompilationInfo {
     kSplittingEnabled = 1 << 13,
     kTypeFeedbackEnabled = 1 << 14,
     kDeoptimizationEnabled = 1 << 15,
-    kSourcePositionsEnabled = 1 << 16
+    kSourcePositionsEnabled = 1 << 16,
+    kNewScript = 1 << 17,
   };
 
   explicit CompilationInfo(ParseInfo* parse_info);
@@ -245,6 +246,10 @@ class CompilationInfo {
 
   bool is_splitting_enabled() const { return GetFlag(kSplittingEnabled); }
 
+  void MarkAsNewScript() { SetFlag(kNewScript); }
+
+  bool is_new_script() const { return GetFlag(kNewScript); }
+
   bool IsCodePreAgingActive() const {
     return FLAG_optimize_for_size && FLAG_age_code && !will_serialize() &&
            !is_debug();

src/objects.cc

@@ -10436,8 +10436,7 @@ MaybeHandle<SharedFunctionInfo> Script::FindSharedFunctionInfo(
       if (!obj->IsSharedFunctionInfo()) continue;
       SharedFunctionInfo* shared = SharedFunctionInfo::cast(obj);
       if (fun->function_token_position() == shared->function_token_position() &&
-          fun->start_position() == shared->start_position() &&
-          fun->end_position() == shared->end_position()) {
+          fun->start_position() == shared->start_position()) {
         return Handle<SharedFunctionInfo>(shared);
       }
     }
@@ -10461,11 +10460,15 @@ void SharedFunctionInfo::SetScript(Handle<SharedFunctionInfo> shared,
   // Add shared function info to new script's list.
   if (script_object->IsScript()) {
     Handle<Script> script = Handle<Script>::cast(script_object);
-    bool found = false;
     Handle<Object> list(script->shared_function_infos(), shared->GetIsolate());
+#ifdef DEBUG
+    bool found = false;
     list = WeakFixedArray::Add(list, shared, WeakFixedArray::kAddIfNotFound,
                                &found);
     CHECK(!found);
+#else
+    list = WeakFixedArray::Add(list, shared, WeakFixedArray::kAlwaysAdd);
+#endif  // DEBUG
     script->set_shared_function_infos(*list);
   }
   // Finally set new script.