[Compiler] Split ScopeInfo allocation out of DeclarationScope::Analyse.

Move ScopeInfo allocation out of DeclarationScope::Analyse and do it later
in the compile when finalizing unoptimized code generation. This is to enable
scope analysis to be done without heap allocation so it could run off-thread.

BUG=v8:5203

Change-Id: I954aacd4353925bbbd5a940d979027de2c52e1fd
Reviewed-on: https://chromium-review.googlesource.com/581108Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46862}

src/ast/scopes.cc

@@ -622,8 +622,7 @@ void DeclarationScope::HoistSloppyBlockFunctions(AstNodeFactory* factory) {
   }
 }
 
-void DeclarationScope::Analyze(ParseInfo* info, Isolate* isolate,
-                               AnalyzeMode mode) {
+void DeclarationScope::Analyze(ParseInfo* info, Isolate* isolate) {
   RuntimeCallTimerScope runtimeTimer(isolate,
                                      &RuntimeCallStats::CompileScopeAnalysis);
   DCHECK(info->literal() != NULL);
@@ -670,13 +669,7 @@ void DeclarationScope::Analyze(ParseInfo* info, Isolate* isolate,
     info->consumed_preparsed_scope_data()->RestoreScopeAllocationData(scope);
   }
 
-  scope->AllocateVariables(info, isolate, mode);
-
-  // Ensuring that the outer script scope has a scope info avoids having
-  // special case for native contexts vs other contexts.
-  if (info->script_scope()->scope_info_.is_null()) {
-    info->script_scope()->scope_info_ = handle(ScopeInfo::Empty(isolate));
-  }
+  scope->AllocateVariables(info);
 
 #ifdef DEBUG
   if (info->script_is_native() ? FLAG_print_builtin_scopes
@@ -1317,29 +1310,13 @@ Declaration* Scope::CheckLexDeclarationsConflictingWith(
   return nullptr;
 }
 
-void DeclarationScope::AllocateVariables(ParseInfo* info, Isolate* isolate,
-                                         AnalyzeMode mode) {
+void DeclarationScope::AllocateVariables(ParseInfo* info) {
   // Module variables must be allocated before variable resolution
   // to ensure that UpdateNeedsHoleCheck() can detect import variables.
   if (is_module_scope()) AsModuleScope()->AllocateModuleVariables();
 
   ResolveVariablesRecursively(info);
   AllocateVariablesRecursively();
-
-  MaybeHandle<ScopeInfo> outer_scope;
-  if (outer_scope_ != nullptr) outer_scope = outer_scope_->scope_info_;
-
-  AllocateScopeInfosRecursively(isolate, outer_scope);
-  if (mode == AnalyzeMode::kDebugger) {
-    AllocateDebuggerScopeInfos(isolate, outer_scope);
-  }
-  // The debugger expects all shared function infos to contain a scope info.
-  // Since the top-most scope will end up in a shared function info, make sure
-  // it has one, even if it doesn't need a scope info.
-  // TODO(jochen|yangguo): Remove this requirement.
-  if (scope_info_.is_null()) {
-    scope_info_ = ScopeInfo::Create(isolate, zone(), this, outer_scope);
-  }
 }
 
 bool Scope::AllowsLazyParsingWithoutUnresolvedVariables(
@@ -2346,6 +2323,38 @@ void Scope::AllocateDebuggerScopeInfos(Isolate* isolate,
   }
 }
 
+// static
+void DeclarationScope::AllocateScopeInfos(ParseInfo* info, Isolate* isolate,
+                                          AnalyzeMode mode) {
+  DeclarationScope* scope = info->literal()->scope();
+  if (!scope->scope_info_.is_null()) return;  // Allocated by outer function.
+
+  MaybeHandle<ScopeInfo> outer_scope;
+  if (scope->outer_scope_ != nullptr) {
+    outer_scope = scope->outer_scope_->scope_info_;
+  }
+
+  scope->AllocateScopeInfosRecursively(isolate, outer_scope);
+  if (mode == AnalyzeMode::kDebugger) {
+    scope->AllocateDebuggerScopeInfos(isolate, outer_scope);
+  }
+
+  // The debugger expects all shared function infos to contain a scope info.
+  // Since the top-most scope will end up in a shared function info, make sure
+  // it has one, even if it doesn't need a scope info.
+  // TODO(jochen|yangguo): Remove this requirement.
+  if (scope->scope_info_.is_null()) {
+    scope->scope_info_ =
+        ScopeInfo::Create(isolate, scope->zone(), scope, outer_scope);
+  }
+
+  // Ensuring that the outer script scope has a scope info avoids having
+  // special case for native contexts vs other contexts.
+  if (info->script_scope() && info->script_scope()->scope_info_.is_null()) {
+    info->script_scope()->scope_info_ = handle(ScopeInfo::Empty(isolate));
+  }
+}
+
 int Scope::StackLocalCount() const {
   Variable* function =
       is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;

src/ast/scopes.h

@@ -861,7 +861,7 @@ class V8_EXPORT_PRIVATE DeclarationScope : public Scope {
   // Compute top scope and allocate variables. For lazy compilation the top
   // scope only contains the single lazily compiled function, so this
   // doesn't re-allocate variables repeatedly.
-  static void Analyze(ParseInfo* info, Isolate* isolate, AnalyzeMode mode);
+  static void Analyze(ParseInfo* info, Isolate* isolate);
 
   // To be called during parsing. Do just enough scope analysis that we can
   // discard the Scope contents for lazily compiled functions. In particular,
@@ -870,6 +870,11 @@ class V8_EXPORT_PRIVATE DeclarationScope : public Scope {
   // and recreates them with the correct Zone with ast_node_factory.
   void AnalyzePartially(AstNodeFactory* ast_node_factory);
 
+  // Allocate ScopeInfos for top scope and any inner scopes that need them.
+  // Does nothing if ScopeInfo is already allocated.
+  static void AllocateScopeInfos(ParseInfo* info, Isolate* isolate,
+                                 AnalyzeMode mode);
+
   Handle<StringSet> CollectNonLocals(ParseInfo* info,
                                      Handle<StringSet> non_locals);
 
@@ -927,7 +932,7 @@ class V8_EXPORT_PRIVATE DeclarationScope : public Scope {
   // In the case of code compiled and run using 'eval', the context
   // parameter is the context in which eval was called.  In all other
   // cases the context parameter is an empty handle.
-  void AllocateVariables(ParseInfo* info, Isolate* isolate, AnalyzeMode mode);
+  void AllocateVariables(ParseInfo* info);
 
   void SetDefaults();
 

src/compiler.cc

@@ -401,6 +401,10 @@ CompilationJob::Status FinalizeUnoptimizedCompilationJob(CompilationJob* job) {
   ParseInfo* parse_info = info->parse_info();
   Isolate* isolate = info->isolate();
 
+  // Allocate scope infos for the literal.
+  DeclarationScope::AllocateScopeInfos(parse_info, isolate,
+                                       AnalyzeMode::kRegular);
+
   if (parse_info->is_toplevel()) {
     // Allocate a shared function info and an array for shared function infos
     // for inner functions.
@@ -445,6 +449,8 @@ bool GenerateUnoptimizedCode(CompilationInfo* info) {
     wasm_data = AsmJs::CompileAsmViaWasm(info);
     if (!wasm_data.is_null()) {
       SetSharedFunctionFlagsFromLiteral(info->literal(), info->shared_info());
+      DeclarationScope::AllocateScopeInfos(info->parse_info(), info->isolate(),
+                                           AnalyzeMode::kRegular);
       info->shared_info()->set_asm_wasm_data(*wasm_data.ToHandleChecked());
       info->SetCode(info->isolate()->builtins()->InstantiateAsmJs());
       InstallUnoptimizedCode(info);
@@ -545,13 +551,18 @@ bool CompileUnoptimizedCode(CompilationInfo* info,
     }
   }
 
-  if (info->parse_info()->is_toplevel() &&
-      (ShouldUseFullCodegen(info->literal()) ||
-       InnerFunctionShouldUseFullCodegen(&inner_literals))) {
+  if (ShouldUseFullCodegen(info->literal()) ||
+      InnerFunctionShouldUseFullCodegen(&inner_literals)) {
+    inner_function_mode = ConcurrencyMode::kNotConcurrent;
+
+    // Full-codegen needs to access ScopeInfos when compiling, so allocate now.
+    DeclarationScope::AllocateScopeInfos(info->parse_info(), isolate,
+                                         AnalyzeMode::kRegular);
+    if (info->parse_info()->is_toplevel()) {
       // Full-codegen needs to access SFI when compiling, so allocate the array
       // now.
       EnsureSharedFunctionInfosArrayOnScript(info);
-    inner_function_mode = ConcurrencyMode::kNotConcurrent;
+    }
   }
 
   std::shared_ptr<Zone> parse_zone;
@@ -674,6 +685,8 @@ bool GetOptimizedCodeNow(CompilationJob* job) {
   // Parsing is not required when optimizing from existing bytecode.
   if (!info->is_optimizing_from_bytecode()) {
     if (!Compiler::ParseAndAnalyze(info)) return false;
+    DeclarationScope::AllocateScopeInfos(info->parse_info(), isolate,
+                                         AnalyzeMode::kRegular);
     EnsureFeedbackMetadata(info);
   }
 
@@ -729,6 +742,8 @@ bool GetOptimizedCodeLater(CompilationJob* job) {
   // Parsing is not required when optimizing from existing bytecode.
   if (!info->is_optimizing_from_bytecode()) {
     if (!Compiler::ParseAndAnalyze(info)) return false;
+    DeclarationScope::AllocateScopeInfos(info->parse_info(), isolate,
+                                         AnalyzeMode::kRegular);
     EnsureFeedbackMetadata(info);
   }
 
@@ -1079,7 +1094,7 @@ bool Compiler::Analyze(ParseInfo* info, Isolate* isolate,
   RuntimeCallTimerScope runtimeTimer(isolate,
                                      &RuntimeCallStats::CompileAnalyse);
   if (!Rewriter::Rewrite(info, isolate)) return false;
-  DeclarationScope::Analyze(info, isolate, AnalyzeMode::kRegular);
+  DeclarationScope::Analyze(info, isolate);
   if (!Renumber(info, eager_literals)) {
     return false;
   }

src/debug/debug-scopes.cc

@@ -121,7 +121,9 @@ void ScopeIterator::TryParseAndRetrieveScopes(ScopeIterator::Option option) {
       CollectNonLocals(info.get(), scope);
     }
     if (!ignore_nested_scopes) {
-      DeclarationScope::Analyze(info.get(), isolate_, AnalyzeMode::kDebugger);
+      DeclarationScope::Analyze(info.get(), isolate_);
+      DeclarationScope::AllocateScopeInfos(info.get(), isolate_,
+                                           AnalyzeMode::kDebugger);
       RetrieveScopeChain(scope);
     }
   } else {

test/cctest/compiler/test-loop-assignment-analysis.cc

@@ -41,8 +41,7 @@ struct TestHelper : public HandleAndZoneScope {
     CHECK(parsing::ParseFunction(&parse_info, info.shared_info(),
                                  info.isolate()));
     CHECK(Rewriter::Rewrite(&parse_info, function->GetIsolate()));
-    DeclarationScope::Analyze(&parse_info, info.isolate(),
-                              AnalyzeMode::kRegular);
+    DeclarationScope::Analyze(&parse_info, info.isolate());
 
     DeclarationScope* scope = info.literal()->scope();
     AstValueFactory* factory = parse_info.ast_value_factory();

test/cctest/test-parsing.cc

@@ -834,7 +834,9 @@ TEST(ScopeUsesArgumentsSuperThis) {
       info.set_allow_lazy_parsing(false);
       CHECK(i::parsing::ParseProgram(&info, isolate));
       CHECK(i::Rewriter::Rewrite(&info, isolate));
-      i::DeclarationScope::Analyze(&info, isolate, i::AnalyzeMode::kRegular);
+      i::DeclarationScope::Analyze(&info, isolate);
+      i::DeclarationScope::AllocateScopeInfos(&info, isolate,
+                                              i::AnalyzeMode::kRegular);
       CHECK(info.literal() != NULL);
 
       i::DeclarationScope* script_scope = info.literal()->scope();
@@ -10267,7 +10269,9 @@ TEST(LexicalLoopVariable) {
     info.set_allow_lazy_parsing(false);
     CHECK(i::parsing::ParseProgram(&info, isolate));
     CHECK(i::Rewriter::Rewrite(&info, isolate));
-    i::DeclarationScope::Analyze(&info, isolate, i::AnalyzeMode::kRegular);
+    i::DeclarationScope::Analyze(&info, isolate);
+    i::DeclarationScope::AllocateScopeInfos(&info, isolate,
+                                            i::AnalyzeMode::kRegular);
     CHECK(info.literal() != NULL);
 
     i::DeclarationScope* script_scope = info.literal()->scope();

test/unittests/compiler-dispatcher/compiler-dispatcher-unittest.cc

@@ -1019,8 +1019,8 @@ TEST_F(CompilerDispatcherTest, CompileParsedOutOfScope) {
     ASSERT_FALSE(shared->is_compiled());
     ParseInfo parse_info(shared);
 
-    ASSERT_TRUE(parsing::ParseAny(&parse_info, shared, i_isolate()));
     DeferredHandleScope handles_scope(i_isolate());
+    ASSERT_TRUE(parsing::ParseAny(&parse_info, shared, i_isolate()));
     { ASSERT_TRUE(Compiler::Analyze(&parse_info, i_isolate())); }
     std::shared_ptr<DeferredHandles> compilation_handles(
         handles_scope.Detach());