This is a workaround for the fact that %SetCode can "lose" the script for a js...

This is a workaround for the fact that %SetCode can "lose" the script for a js native. If the js native is re-initialized (for a Realm or something), then the source SharedFunctionInfo won't have a script anymore. Nonetheless, we may want to optimize the function. If we've compiled bytecode, then we can compile optimized code without a script.

Here, we carve out a special exception for this case, so that we can turn on the --mark-shared-functions-for-tier-up.

BUG=v8:5946
R=leszeks@chromium.org

Review-Url: https://codereview.chromium.org/2684033007
Cr-Original-Commit-Position: refs/heads/master@{#43240}
Committed: https://chromium.googlesource.com/v8/v8/+/4123a3dd790495c40cf839990318a85c146e057d
Review-Url: https://codereview.chromium.org/2684033007
Cr-Commit-Position: refs/heads/master@{#43252}

src/compiler.cc

@@ -348,10 +348,8 @@ bool UseTurboFan(Handle<SharedFunctionInfo> shared) {
          passes_turbo_filter;
 }
 
-bool ShouldUseIgnition(CompilationInfo* info) {
-  DCHECK(info->has_shared_info());
-  Handle<SharedFunctionInfo> shared = info->shared_info();
-
+bool ShouldUseIgnition(Handle<SharedFunctionInfo> shared,
+                       bool marked_as_debug) {
   // Code which can't be supported by the old pipeline should use Ignition.
   if (shared->must_use_ignition_turbo()) return true;
 
@@ -370,7 +368,7 @@ bool ShouldUseIgnition(CompilationInfo* info) {
 
   // When requesting debug code as a replacement for existing code, we provide
   // the same kind as the existing code (to prevent implicit tier-change).
-  if (info->is_debug() && shared->is_compiled()) {
+  if (marked_as_debug && shared->is_compiled()) {
     return !shared->HasBaselineCode();
   }
 
@@ -381,6 +379,11 @@ bool ShouldUseIgnition(CompilationInfo* info) {
   return FLAG_ignition;
 }
 
+bool ShouldUseIgnition(CompilationInfo* info) {
+  DCHECK(info->has_shared_info());
+  return ShouldUseIgnition(info->shared_info(), info->is_debug());
+}
+
 bool UseAsmWasm(DeclarationScope* scope, Handle<SharedFunctionInfo> shared_info,
                 bool is_debug) {
   return FLAG_validate_asm && scope->asm_module() &&
@@ -845,8 +848,12 @@ MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
   DCHECK(!isolate->has_pending_exception());
   PostponeInterruptsScope postpone(isolate);
   bool use_turbofan = UseTurboFan(shared) || ignition_osr;
+  bool has_script = shared->script()->IsScript();
+  // BUG(5946): This DCHECK is necessary to make certain that we won't tolerate
+  // the lack of a script without bytecode.
+  DCHECK_IMPLIES(!has_script, ShouldUseIgnition(shared, false));
   std::unique_ptr<CompilationJob> job(
-      use_turbofan ? compiler::Pipeline::NewCompilationJob(function)
+      use_turbofan ? compiler::Pipeline::NewCompilationJob(function, has_script)
                    : new HCompilationJob(function));
   CompilationInfo* info = job->info();
   ParseInfo* parse_info = info->parse_info();
@@ -1069,17 +1076,10 @@ MaybeHandle<Code> GetLazyCode(Handle<JSFunction> function) {
 
     switch (Compiler::NextCompilationTier(*function)) {
       case Compiler::BASELINE: {
-        if (FLAG_trace_opt) {
-          PrintF("[recompiling function ");
-          function->ShortPrint();
-          PrintF(
-              " to baseline eagerly (shared function marked for tier up)]\n");
-        }
-
-        Handle<Code> code;
-        if (GetBaselineCode(function).ToHandle(&code)) {
-          return code;
-        }
+        // We don't try to handle baseline here because GetBaselineCode()
+        // doesn't handle top-level code. We aren't supporting
+        // the hybrid pipeline going forward (where Ignition is a first
+        // tier followed by full-code).
         break;
       }
       case Compiler::OPTIMIZED: {

src/compiler/pipeline.cc

@@ -545,13 +545,13 @@ PipelineStatistics* CreatePipelineStatistics(CompilationInfo* info,
 
 class PipelineCompilationJob final : public CompilationJob {
  public:
-  PipelineCompilationJob(Isolate* isolate, Handle<JSFunction> function)
+  PipelineCompilationJob(ParseInfo* parse_info, Handle<JSFunction> function)
       // Note that the CompilationInfo is not initialized at the time we pass it
       // to the CompilationJob constructor, but it is not dereferenced there.
-      : CompilationJob(isolate, &info_, "TurboFan"),
-        parse_info_(handle(function->shared())),
-        zone_stats_(isolate->allocator()),
-        info_(parse_info_.zone(), &parse_info_, function),
+      : CompilationJob(parse_info->isolate(), &info_, "TurboFan"),
+        parse_info_(parse_info),
+        zone_stats_(parse_info->isolate()->allocator()),
+        info_(parse_info_.get()->zone(), parse_info_.get(), function),
         pipeline_statistics_(CreatePipelineStatistics(info(), &zone_stats_)),
         data_(&zone_stats_, info(), pipeline_statistics_.get()),
         pipeline_(&data_),
@@ -563,7 +563,7 @@ class PipelineCompilationJob final : public CompilationJob {
   Status FinalizeJobImpl() final;
 
  private:
-  ParseInfo parse_info_;
+  std::unique_ptr<ParseInfo> parse_info_;
   ZoneStats zone_stats_;
   CompilationInfo info_;
   std::unique_ptr<PipelineStatistics> pipeline_statistics_;
@@ -1750,8 +1750,16 @@ Handle<Code> Pipeline::GenerateCodeForTesting(
 }
 
 // static
-CompilationJob* Pipeline::NewCompilationJob(Handle<JSFunction> function) {
-  return new PipelineCompilationJob(function->GetIsolate(), function);
+CompilationJob* Pipeline::NewCompilationJob(Handle<JSFunction> function,
+                                            bool has_script) {
+  Handle<SharedFunctionInfo> shared = handle(function->shared());
+  ParseInfo* parse_info;
+  if (!has_script) {
+    parse_info = ParseInfo::AllocateWithoutScript(shared);
+  } else {
+    parse_info = new ParseInfo(shared);
+  }
+  return new PipelineCompilationJob(parse_info, function);
 }
 
 // static

src/compiler/pipeline.h

@@ -34,7 +34,8 @@ class SourcePositionTable;
 class Pipeline : public AllStatic {
  public:
   // Returns a new compilation job for the given function.
-  static CompilationJob* NewCompilationJob(Handle<JSFunction> function);
+  static CompilationJob* NewCompilationJob(Handle<JSFunction> function,
+                                           bool has_script);
 
   // Returns a new compilation job for the WebAssembly compilation info.
   static CompilationJob* NewWasmCompilationJob(

src/parsing/parse-info.cc

@@ -100,6 +100,46 @@ ParseInfo::~ParseInfo() {
   ast_value_factory_ = nullptr;
 }
 
+// static
+ParseInfo* ParseInfo::AllocateWithoutScript(Handle<SharedFunctionInfo> shared) {
+  Isolate* isolate = shared->GetIsolate();
+  ParseInfo* p = new ParseInfo(isolate->allocator());
+  p->isolate_ = isolate;
+
+  p->set_toplevel(shared->is_toplevel());
+  p->set_allow_lazy_parsing(FLAG_lazy_inner_functions);
+  p->set_hash_seed(isolate->heap()->HashSeed());
+  p->set_is_named_expression(shared->is_named_expression());
+  p->set_calls_eval(shared->scope_info()->CallsEval());
+  p->set_compiler_hints(shared->compiler_hints());
+  p->set_start_position(shared->start_position());
+  p->set_end_position(shared->end_position());
+  p->function_literal_id_ = shared->function_literal_id();
+  p->set_stack_limit(isolate->stack_guard()->real_climit());
+  p->set_unicode_cache(isolate->unicode_cache());
+  p->set_language_mode(shared->language_mode());
+  p->set_shared_info(shared);
+  p->set_module(shared->kind() == FunctionKind::kModule);
+
+  // BUG(5946): This function exists as a workaround until we can
+  // get rid of %SetCode in our native functions. The ParseInfo
+  // is explicitly set up for the case that:
+  // a) you have a native built-in,
+  // b) it's being run for the 2nd-Nth time in an isolate,
+  // c) we've already compiled bytecode and therefore don't need
+  //    to parse.
+  // We tolerate a ParseInfo without a Script in this case.
+  p->set_native(true);
+  p->set_eval(false);
+
+  Handle<HeapObject> scope_info(shared->outer_scope_info());
+  if (!scope_info->IsTheHole(isolate) &&
+      Handle<ScopeInfo>::cast(scope_info)->length() > 0) {
+    p->set_outer_scope_info(Handle<ScopeInfo>::cast(scope_info));
+  }
+  return p;
+}
+
 DeclarationScope* ParseInfo::scope() const { return literal()->scope(); }
 
 bool ParseInfo::is_declaration() const {

src/parsing/parse-info.h

@@ -42,6 +42,8 @@ class V8_EXPORT_PRIVATE ParseInfo {
 
   ~ParseInfo();
 
+  static ParseInfo* AllocateWithoutScript(Handle<SharedFunctionInfo> shared);
+
   Zone* zone() const { return zone_.get(); }
 
   std::shared_ptr<Zone> zone_shared() const { return zone_; }

src/source-position.cc

@@ -11,10 +11,16 @@ namespace internal {
 
 std::ostream& operator<<(std::ostream& out, const SourcePositionInfo& pos) {
   Handle<SharedFunctionInfo> function(pos.function);
-  Handle<Script> script(Script::cast(function->script()));
+  String* name = nullptr;
+  if (function->script()->IsScript()) {
+    Script* script = Script::cast(function->script());
+    if (script->name()->IsString()) {
+      name = String::cast(script->name());
+    }
+  }
   out << "<";
-  if (script->name()->IsString()) {
-    out << String::cast(script->name())->ToCString(DISALLOW_NULLS).get();
+  if (name != nullptr) {
+    out << name->ToCString(DISALLOW_NULLS).get();
   } else {
     out << "unknown";
   }
@@ -78,12 +84,15 @@ std::vector<SourcePositionInfo> SourcePosition::InliningStack(
 
 void SourcePosition::Print(std::ostream& out,
                            SharedFunctionInfo* function) const {
-  Script* script = Script::cast(function->script());
-  Object* source_name = script->name();
   Script::PositionInfo pos;
-  script->GetPositionInfo(ScriptOffset(), &pos, Script::WITH_OFFSET);
+  Object* source_name = nullptr;
+  if (function->script()->IsScript()) {
+    Script* script = Script::cast(function->script());
+    source_name = script->name();
+    script->GetPositionInfo(ScriptOffset(), &pos, Script::WITH_OFFSET);
+  }
   out << "<";
-  if (source_name->IsString()) {
+  if (source_name != nullptr && source_name->IsString()) {
     out << String::cast(source_name)
                ->ToCString(DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL)
                .get();
@@ -117,12 +126,14 @@ void SourcePosition::Print(std::ostream& out, Code* code) const {
 SourcePositionInfo::SourcePositionInfo(SourcePosition pos,
                                        Handle<SharedFunctionInfo> f)
     : position(pos), function(f) {
-  Handle<Script> script(Script::cast(function->script()));
-  Script::PositionInfo info;
-  if (Script::GetPositionInfo(script, pos.ScriptOffset(), &info,
-                              Script::WITH_OFFSET)) {
-    line = info.line;
-    column = info.column;
+  if (function->script()->IsScript()) {
+    Handle<Script> script(Script::cast(function->script()));
+    Script::PositionInfo info;
+    if (Script::GetPositionInfo(script, pos.ScriptOffset(), &info,
+                                Script::WITH_OFFSET)) {
+      line = info.line;
+      column = info.column;
+    }
   }
 }
 

test/mjsunit/mjsunit.status

@@ -544,7 +544,6 @@
 
   # Forced optimisation path tests.
   'shared-function-tier-up-default': [SKIP],
-  'shared-function-tier-up-ignition': [SKIP],
   'shared-function-tier-up-turbo': [SKIP],
 
   # Fails deopt_fuzzer due to --deopt_every_n_times or

test/mjsunit/shared-function-tier-up-ignition.js

-// Copyright 2016 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// Flags: --mark-shared-functions-for-tier-up --allow-natives-syntax
-// Flags: --ignition-staging --no-turbo
-// Flags: --crankshaft --no-always-opt
-
-// If we are always or never optimizing it is useless.
-assertFalse(isAlwaysOptimize());
-assertFalse(isNeverOptimize());
-
-(function() {
-  var sum = 0;
-  var i = 0;
-  for (var i = 0; i < 5; ++i) {
-    var f = function(x) {
-      return 2 * x;
-    }
-    sum += f(i);
-
-    if (i == 1) {
-      // f must be interpreted code.
-      assertTrue(isInterpreted(f));
-
-      // Allow it to run twice (i = 0, 1), then tier-up to baseline.
-      %BaselineFunctionOnNextCall(f);
-    } else if (i == 2) {
-      // Tier-up at i = 2 should only go up to baseline.
-      assertTrue(isBaselined(f));
-
-    } else if (i == 3) {
-      // Now f must be baseline code.
-      assertTrue(isBaselined(f));
-
-      // Run two more times (i = 2, 3), then tier-up to optimized.
-      %OptimizeFunctionOnNextCall(f);
-    } else if (i == 4) {
-      // Tier-up at i = 4 should now go up to crankshaft.
-      assertTrue(isCrankshafted(f));
-    }
-  }
-})()