Keep a canonical list of shared function infos.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index ef21f1f46f9e65ff227bdefb703fe4132101c59e..db92c2b20f4c86721aed29341bc6ecf4fd6dba68 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1013,6 +1013,9 @@ void Compiler::CompileForLiveEdit(Handle<Script> script) {
   PostponeInterruptsScope postpone(info.isolate());
   VMState<COMPILER> state(info.isolate());
 
+  // Get rid of old list of shared function infos.
+  script->set_shared_function_infos(Smi::FromInt(0));
+
   info.parse_info()->set_global();
   if (!Parser::ParseStatic(info.parse_info())) return;
 
@@ -1099,7 +1102,7 @@ static Handle<SharedFunctionInfo> CompileToplevel(CompilationInfo* info) {
 
     DCHECK_EQ(RelocInfo::kNoPosition, lit->function_token_position());
     SharedFunctionInfo::InitFromFunctionLiteral(result, lit);
-    result->set_script(*script);
+    SharedFunctionInfo::SetScript(result, script);
     result->set_is_toplevel(true);
 
     Handle<String> script_name = script->name()->IsString()
@@ -1332,10 +1335,20 @@ Handle<SharedFunctionInfo> Compiler::CompileStreamedScript(
 }
 
 
-Handle<SharedFunctionInfo> Compiler::BuildFunctionInfo(
+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);
+  // 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.
+  Handle<SharedFunctionInfo> existing;
+  if (maybe_existing.ToHandle(&existing) && existing->is_compiled()) {
+    return existing;
+  }
+
   Zone zone;
   ParseInfo parse_info(&zone, script);
   CompilationInfo info(&parse_info);
@@ -1396,25 +1409,34 @@ Handle<SharedFunctionInfo> Compiler::BuildFunctionInfo(
     return Handle<SharedFunctionInfo>::null();
   }
 
-  // Create a shared function info object.
-  Handle<SharedFunctionInfo> result = factory->NewSharedFunctionInfo(
-      literal->name(), literal->materialized_literal_count(), literal->kind(),
-      info.code(), scope_info, info.feedback_vector());
+  if (maybe_existing.is_null()) {
+    // Create a shared function info object.
+    Handle<SharedFunctionInfo> result = factory->NewSharedFunctionInfo(
+        literal->name(), literal->materialized_literal_count(), literal->kind(),
+        info.code(), scope_info, info.feedback_vector());
 
-  SharedFunctionInfo::InitFromFunctionLiteral(result, literal);
-  result->set_script(*script);
-  result->set_is_toplevel(false);
+    SharedFunctionInfo::InitFromFunctionLiteral(result, literal);
+    SharedFunctionInfo::SetScript(result, script);
+    result->set_is_toplevel(false);
 
-  RecordFunctionCompilation(Logger::FUNCTION_TAG, &info, result);
-  result->set_allows_lazy_compilation(literal->AllowsLazyCompilation());
-  result->set_allows_lazy_compilation_without_context(allow_lazy_without_ctx);
+    RecordFunctionCompilation(Logger::FUNCTION_TAG, &info, result);
+    result->set_allows_lazy_compilation(literal->AllowsLazyCompilation());
+    result->set_allows_lazy_compilation_without_context(allow_lazy_without_ctx);
 
-  // Set the expected number of properties for instances and return
-  // the resulting function.
-  SetExpectedNofPropertiesFromEstimate(result,
-                                       literal->expected_property_count());
-  live_edit_tracker.RecordFunctionInfo(result, literal, info.zone());
-  return result;
+    // Set the expected number of properties for instances and return
+    // the resulting function.
+    SetExpectedNofPropertiesFromEstimate(result,
+                                         literal->expected_property_count());
+    live_edit_tracker.RecordFunctionInfo(result, literal, info.zone());
+    return result;
+  } else {
+    // We may have additional data from compilation now.
+    DCHECK(!existing->is_compiled());
+    existing->ReplaceCode(*info.code());
+    existing->set_scope_info(*scope_info);
+    existing->set_feedback_vector(*info.feedback_vector());
+    return existing;
+  }
 }