compiler.cc

// Copyright 2012 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.

#include "src/compiler.h"

#include <algorithm>
#include <memory>

#include "src/asmjs/asm-js.h"
#include "src/assembler-inl.h"
#include "src/ast/ast-numbering.h"
#include "src/ast/prettyprinter.h"
#include "src/ast/scopes.h"
#include "src/base/optional.h"
#include "src/bootstrapper.h"
#include "src/codegen.h"
#include "src/compilation-cache.h"
#include "src/compilation-info.h"
#include "src/compiler-dispatcher/compiler-dispatcher.h"
#include "src/compiler-dispatcher/optimizing-compile-dispatcher.h"
#include "src/compiler/pipeline.h"
#include "src/debug/debug.h"
#include "src/debug/liveedit.h"
#include "src/frames-inl.h"
#include "src/globals.h"
#include "src/heap/heap.h"
#include "src/interpreter/interpreter.h"
#include "src/isolate-inl.h"
#include "src/log-inl.h"
#include "src/messages.h"
#include "src/objects/map.h"
#include "src/parsing/parse-info.h"
#include "src/parsing/parsing.h"
#include "src/parsing/rewriter.h"
#include "src/parsing/scanner-character-streams.h"
#include "src/runtime-profiler.h"
#include "src/snapshot/code-serializer.h"
#include "src/vm-state-inl.h"

namespace v8 {
namespace internal {

// A wrapper around a CompilationInfo that detaches the Handles from
// the underlying DeferredHandleScope and stores them in info_ on
// destruction.
class CompilationHandleScope final {
 public:
  explicit CompilationHandleScope(CompilationInfo* info)
      : deferred_(info->isolate()), info_(info) {}
  ~CompilationHandleScope() { info_->set_deferred_handles(deferred_.Detach()); }

 private:
  DeferredHandleScope deferred_;
  CompilationInfo* info_;
};

// Helper that times a scoped region and records the elapsed time.
struct ScopedTimer {
  explicit ScopedTimer(base::TimeDelta* location) : location_(location) {
    DCHECK(location_ != NULL);
    timer_.Start();
  }

  ~ScopedTimer() { *location_ += timer_.Elapsed(); }

  base::ElapsedTimer timer_;
  base::TimeDelta* location_;
};

// ----------------------------------------------------------------------------
// Implementation of CompilationJob

CompilationJob::CompilationJob(Isolate* isolate, ParseInfo* parse_info,
                               CompilationInfo* compilation_info,
                               const char* compiler_name, State initial_state)
    : parse_info_(parse_info),
      compilation_info_(compilation_info),
      isolate_thread_id_(isolate->thread_id()),
      compiler_name_(compiler_name),
      state_(initial_state),
      stack_limit_(isolate->stack_guard()->real_climit()),
      executed_on_background_thread_(false) {}

CompilationJob::Status CompilationJob::PrepareJob() {
  DCHECK(
      ThreadId::Current().Equals(compilation_info()->isolate()->thread_id()));
  DisallowJavascriptExecution no_js(isolate());

  if (FLAG_trace_opt && compilation_info()->IsOptimizing()) {
    OFStream os(stdout);
    os << "[compiling method " << Brief(*compilation_info()->closure())
       << " using " << compiler_name_;
    if (compilation_info()->is_osr()) os << " OSR";
    os << "]" << std::endl;
  }

  // Delegate to the underlying implementation.
  DCHECK(state() == State::kReadyToPrepare);
  ScopedTimer t(&time_taken_to_prepare_);
  return UpdateState(PrepareJobImpl(), State::kReadyToExecute);
}

CompilationJob::Status CompilationJob::ExecuteJob() {
  base::Optional<DisallowHeapAllocation> no_allocation;
  base::Optional<DisallowHandleAllocation> no_handles;
  base::Optional<DisallowHandleDereference> no_deref;
  base::Optional<DisallowCodeDependencyChange> no_dependency_change;
  if (can_execute_on_background_thread()) {
    no_allocation.emplace();
    no_handles.emplace();
    no_deref.emplace();
    no_dependency_change.emplace();
    executed_on_background_thread_ =
        !ThreadId::Current().Equals(isolate_thread_id_);
  } else {
    DCHECK(ThreadId::Current().Equals(isolate_thread_id_));
  }

  // Delegate to the underlying implementation.
  DCHECK(state() == State::kReadyToExecute);
  ScopedTimer t(&time_taken_to_execute_);
  return UpdateState(ExecuteJobImpl(), State::kReadyToFinalize);
}

CompilationJob::Status CompilationJob::FinalizeJob() {
  DCHECK(
      ThreadId::Current().Equals(compilation_info()->isolate()->thread_id()));
  DisallowCodeDependencyChange no_dependency_change;
  DisallowJavascriptExecution no_js(isolate());
  DCHECK(!compilation_info()->dependencies()->HasAborted());

  // Delegate to the underlying implementation.
  DCHECK(state() == State::kReadyToFinalize);
  ScopedTimer t(&time_taken_to_finalize_);
  return UpdateState(FinalizeJobImpl(), State::kSucceeded);
}

CompilationJob::Status CompilationJob::RetryOptimization(BailoutReason reason) {
  DCHECK(compilation_info_->IsOptimizing());
  compilation_info_->RetryOptimization(reason);
  state_ = State::kFailed;
  return FAILED;
}

CompilationJob::Status CompilationJob::AbortOptimization(BailoutReason reason) {
  DCHECK(compilation_info_->IsOptimizing());
  compilation_info_->AbortOptimization(reason);
  state_ = State::kFailed;
  return FAILED;
}

void CompilationJob::RecordUnoptimizedCompilationStats() const {
  int code_size;
  if (compilation_info()->has_bytecode_array()) {
    code_size = compilation_info()->bytecode_array()->SizeIncludingMetadata();
  } else {
    code_size = compilation_info()->code()->SizeIncludingMetadata();
  }

  Counters* counters = isolate()->counters();
  // TODO(4280): Rename counters from "baseline" to "unoptimized" eventually.
  counters->total_baseline_code_size()->Increment(code_size);
  counters->total_baseline_compile_count()->Increment(1);

  // TODO(5203): Add timers for each phase of compilation.
}

void CompilationJob::RecordOptimizedCompilationStats() const {
  DCHECK(compilation_info()->IsOptimizing());
  Handle<JSFunction> function = compilation_info()->closure();
  double ms_creategraph = time_taken_to_prepare_.InMillisecondsF();
  double ms_optimize = time_taken_to_execute_.InMillisecondsF();
  double ms_codegen = time_taken_to_finalize_.InMillisecondsF();
  if (FLAG_trace_opt) {
    PrintF("[optimizing ");
    function->ShortPrint();
    PrintF(" - took %0.3f, %0.3f, %0.3f ms]\n", ms_creategraph, ms_optimize,
           ms_codegen);
  }
  if (FLAG_trace_opt_stats) {
    static double compilation_time = 0.0;
    static int compiled_functions = 0;
    static int code_size = 0;

    compilation_time += (ms_creategraph + ms_optimize + ms_codegen);
    compiled_functions++;
    code_size += function->shared()->SourceSize();
    PrintF("Compiled: %d functions with %d byte source size in %fms.\n",
           compiled_functions, code_size, compilation_time);
  }
}

Isolate* CompilationJob::isolate() const {
  return compilation_info()->isolate();
}

// ----------------------------------------------------------------------------
// Local helper methods that make up the compilation pipeline.

namespace {

void RecordFunctionCompilation(CodeEventListener::LogEventsAndTags tag,
                               CompilationInfo* compilation_info) {
  // Log the code generation. If source information is available include
  // script name and line number. Check explicitly whether logging is
  // enabled as finding the line number is not free.
  if (compilation_info->isolate()->logger()->is_logging_code_events() ||
      compilation_info->isolate()->is_profiling()) {
    Handle<SharedFunctionInfo> shared = compilation_info->shared_info();
    Handle<Script> script = compilation_info->script();
    Handle<AbstractCode> abstract_code =
        compilation_info->has_bytecode_array()
            ? Handle<AbstractCode>::cast(compilation_info->bytecode_array())
            : Handle<AbstractCode>::cast(compilation_info->code());
    if (abstract_code.is_identical_to(
            BUILTIN_CODE(compilation_info->isolate(), CompileLazy))) {
      return;
    }
    int line_num = Script::GetLineNumber(script, shared->start_position()) + 1;
    int column_num =
        Script::GetColumnNumber(script, shared->start_position()) + 1;
    String* script_name =
        script->name()->IsString()
            ? String::cast(script->name())
            : compilation_info->isolate()->heap()->empty_string();
    CodeEventListener::LogEventsAndTags log_tag =
        Logger::ToNativeByScript(tag, *script);
    PROFILE(compilation_info->isolate(),
            CodeCreateEvent(log_tag, *abstract_code, *shared, script_name,
                            line_num, column_num));
  }
}

void EnsureFeedbackMetadata(CompilationInfo* compilation_info) {
  DCHECK(compilation_info->has_shared_info());

  // If no type feedback metadata exists, create it. At this point the
  // AstNumbering pass has already run. Note the snapshot can contain outdated
  // vectors for a different configuration, hence we also recreate a new vector
  // when the function is not compiled (i.e. no code was serialized).

  // TODO(mvstanton): reintroduce is_empty() predicate to feedback_metadata().
  if (compilation_info->shared_info()->feedback_metadata()->length() == 0 ||
      !compilation_info->shared_info()->is_compiled()) {
    Handle<FeedbackMetadata> feedback_metadata = FeedbackMetadata::New(
        compilation_info->isolate(),
        compilation_info->literal()->feedback_vector_spec());
    compilation_info->shared_info()->set_feedback_metadata(*feedback_metadata);
  }

  // It's very important that recompiles do not alter the structure of the type
  // feedback vector. Verify that the structure fits the function literal.
  CHECK(!compilation_info->shared_info()->feedback_metadata()->SpecDiffersFrom(
      compilation_info->literal()->feedback_vector_spec()));
}

bool UseAsmWasm(FunctionLiteral* literal, bool asm_wasm_broken) {
  // Check whether asm.js validation is enabled.
  if (!FLAG_validate_asm) return false;

  // Modules that have validated successfully, but were subsequently broken by
  // invalid module instantiation attempts are off limit forever.
  if (asm_wasm_broken) return false;

  // In stress mode we want to run the validator on everything.
  if (FLAG_stress_validate_asm) return true;

  // In general, we respect the "use asm" directive.
  return literal->scope()->IsAsmModule();
}

void InstallUnoptimizedCode(CompilationInfo* compilation_info) {
  Handle<SharedFunctionInfo> shared = compilation_info->shared_info();
  DCHECK_EQ(compilation_info->shared_info()->language_mode(),
            compilation_info->literal()->language_mode());

  // Ensure feedback metadata is installed.
  EnsureFeedbackMetadata(compilation_info);

  // Update the shared function info with the scope info.
  Handle<ScopeInfo> scope_info = compilation_info->scope()->scope_info();
  shared->set_scope_info(*scope_info);
  Scope* outer_scope = compilation_info->scope()->GetOuterScopeWithContext();
  if (outer_scope) {
    shared->set_outer_scope_info(*outer_scope->scope_info());
  }

  DCHECK(!compilation_info->code().is_null());
  shared->ReplaceCode(*compilation_info->code());
  if (compilation_info->has_bytecode_array()) {
    DCHECK(!shared->HasBytecodeArray());  // Only compiled once.
    DCHECK(!compilation_info->has_asm_wasm_data());
    shared->set_bytecode_array(*compilation_info->bytecode_array());
  } else if (compilation_info->has_asm_wasm_data()) {
    shared->set_asm_wasm_data(*compilation_info->asm_wasm_data());
  }

  // Install coverage info on the shared function info.
  if (compilation_info->has_coverage_info()) {
    DCHECK(FLAG_block_coverage &&
           compilation_info->isolate()->is_block_code_coverage());
    compilation_info->isolate()->debug()->InstallCoverageInfo(
        compilation_info->shared_info(), compilation_info->coverage_info());
  }
}

void EnsureSharedFunctionInfosArrayOnScript(ParseInfo* parse_info,
                                            Isolate* isolate) {
  DCHECK(parse_info->is_toplevel());
  DCHECK(!parse_info->script().is_null());
  if (parse_info->script()->shared_function_infos()->length() > 0) {
    DCHECK_EQ(parse_info->script()->shared_function_infos()->length(),
              parse_info->max_function_literal_id() + 1);
    return;
  }
  Handle<FixedArray> infos(isolate->factory()->NewFixedArray(
      parse_info->max_function_literal_id() + 1));
  parse_info->script()->set_shared_function_infos(*infos);
}

void SetSharedFunctionFlagsFromLiteral(FunctionLiteral* literal,
                                       Handle<SharedFunctionInfo> shared_info) {
  // Don't overwrite values set by the bootstrapper.
  if (!shared_info->HasLength()) {
    shared_info->set_length(literal->function_length());
  }
  shared_info->set_has_duplicate_parameters(
      literal->has_duplicate_parameters());
  shared_info->SetExpectedNofPropertiesFromEstimate(literal);
  if (literal->dont_optimize_reason() != kNoReason) {
    shared_info->DisableOptimization(literal->dont_optimize_reason());
  }
}

CompilationJob::Status FinalizeUnoptimizedCompilationJob(CompilationJob* job) {
  CompilationInfo* compilation_info = job->compilation_info();
  ParseInfo* parse_info = job->parse_info();

  SetSharedFunctionFlagsFromLiteral(compilation_info->literal(),
                                    compilation_info->shared_info());

  CompilationJob::Status status = job->FinalizeJob();
  if (status == CompilationJob::SUCCEEDED) {
    InstallUnoptimizedCode(compilation_info);
    CodeEventListener::LogEventsAndTags log_tag;
    if (parse_info->is_toplevel()) {
      log_tag = compilation_info->is_eval() ? CodeEventListener::EVAL_TAG
                                            : CodeEventListener::SCRIPT_TAG;
    } else {
      log_tag = parse_info->lazy_compile() ? CodeEventListener::LAZY_COMPILE_TAG
                                           : CodeEventListener::FUNCTION_TAG;
    }
    RecordFunctionCompilation(log_tag, compilation_info);
    job->RecordUnoptimizedCompilationStats();
  }
  return status;
}

bool Renumber(ParseInfo* parse_info,
              Compiler::EagerInnerFunctionLiterals* eager_literals) {
  RuntimeCallTimerScope runtimeTimer(parse_info->runtime_call_stats(),
                                     &RuntimeCallStats::CompileRenumber);
  return AstNumbering::Renumber(parse_info->stack_limit(), parse_info->zone(),
                                parse_info->literal(), eager_literals,
                                parse_info->collect_type_profile());
}

std::unique_ptr<CompilationJob> PrepareAndExecuteUnoptimizedCompileJob(
    ParseInfo* parse_info, FunctionLiteral* literal, Isolate* isolate) {
  if (UseAsmWasm(literal, parse_info->is_asm_wasm_broken())) {
    std::unique_ptr<CompilationJob> asm_job(
        AsmJs::NewCompilationJob(parse_info, literal, isolate));
    if (asm_job->PrepareJob() == CompilationJob::SUCCEEDED &&
        asm_job->ExecuteJob() == CompilationJob::SUCCEEDED) {
      return asm_job;
    }
    // asm.js validation failed, fall through to standard unoptimized compile.
    // Note: we rely on the fact that AsmJs jobs have done all validation in the
    // PrepareJob and ExecuteJob phases and can't fail in FinalizeJob with
    // with a validation error or another error that could be solve by falling
    // through to standard unoptimized compile.
  }
  std::unique_ptr<CompilationJob> job(
      interpreter::Interpreter::NewCompilationJob(parse_info, literal,
                                                  isolate));
  if (job->PrepareJob() == CompilationJob::SUCCEEDED &&
      job->ExecuteJob() == CompilationJob::SUCCEEDED) {
    return job;
  }
  return std::unique_ptr<CompilationJob>();  // Compilation failed, return null.
}

// TODO(rmcilroy): Remove |isolate| once CompilationJob doesn't need it.
std::unique_ptr<CompilationJob> GenerateUnoptimizedCode(
    ParseInfo* parse_info, Isolate* isolate,
    std::forward_list<std::unique_ptr<CompilationJob>>* inner_function_jobs) {
  DisallowHeapAllocation no_allocation;
  DisallowHandleAllocation no_handles;
  DisallowHandleDereference no_deref;
  DCHECK(inner_function_jobs->empty());

  DCHECK_IMPLIES(parse_info->consumed_preparsed_scope_data()->HasData(),
                 ThreadId::Current().Equals(isolate->thread_id()));

  Compiler::EagerInnerFunctionLiterals inner_literals;
  if (!Compiler::Analyze(parse_info, &inner_literals)) {
    return std::unique_ptr<CompilationJob>();
  }

  // Prepare and execute compilation of the outer-most function.
  std::unique_ptr<CompilationJob> outer_function_job(
      PrepareAndExecuteUnoptimizedCompileJob(parse_info, parse_info->literal(),
                                             isolate));
  if (!outer_function_job) return std::unique_ptr<CompilationJob>();

  // Prepare and execute compilation jobs for eager inner functions.
  for (auto it : inner_literals) {
    FunctionLiteral* inner_literal = it->value();
    std::unique_ptr<CompilationJob> inner_job(
        PrepareAndExecuteUnoptimizedCompileJob(parse_info, inner_literal,
                                               isolate));
    if (!inner_job) return std::unique_ptr<CompilationJob>();
    inner_function_jobs->emplace_front(std::move(inner_job));
  }

  // Character stream shouldn't be used again.
  parse_info->ResetCharacterStream();

  return outer_function_job;
}

bool FinalizeUnoptimizedCode(
    ParseInfo* parse_info, Isolate* isolate,
    Handle<SharedFunctionInfo> shared_info, CompilationJob* outer_function_job,
    std::forward_list<std::unique_ptr<CompilationJob>>* inner_function_jobs) {
  DCHECK(AllowCompilation::IsAllowed(isolate));

  // Allocate scope infos for the literal.
  DeclarationScope::AllocateScopeInfos(parse_info, isolate,
                                       AnalyzeMode::kRegular);

  // Finalize the outer-most function's compilation job.
  outer_function_job->compilation_info()->set_shared_info(shared_info);
  if (FinalizeUnoptimizedCompilationJob(outer_function_job) !=
      CompilationJob::SUCCEEDED) {
    return false;
  }

  // Finalize the inner functions' compilation jobs.
  for (auto&& inner_job : *inner_function_jobs) {
    Handle<SharedFunctionInfo> inner_shared_info =
        Compiler::GetSharedFunctionInfo(
            inner_job->compilation_info()->literal(), parse_info->script(),
            isolate);
    // The inner function might be compiled already if compiling for debug.
    // TODO(rmcilroy): Fix this and DCHECK !is_compiled() once Full-Codegen dies
    if (inner_shared_info->is_compiled()) continue;
    inner_job->compilation_info()->set_shared_info(inner_shared_info);
    if (FinalizeUnoptimizedCompilationJob(inner_job.get()) !=
        CompilationJob::SUCCEEDED) {
      return false;
    }
  }
  return true;
}

MUST_USE_RESULT MaybeHandle<Code> GetCodeFromOptimizedCodeCache(
    Handle<JSFunction> function, BailoutId osr_offset) {
  RuntimeCallTimerScope runtimeTimer(
      function->GetIsolate(),
      &RuntimeCallStats::CompileGetFromOptimizedCodeMap);
  Handle<SharedFunctionInfo> shared(function->shared());
  DisallowHeapAllocation no_gc;
  if (osr_offset.IsNone()) {
    if (function->feedback_vector_cell()->value()->IsFeedbackVector()) {
      FeedbackVector* feedback_vector = function->feedback_vector();
      feedback_vector->EvictOptimizedCodeMarkedForDeoptimization(
          function->shared(), "GetCodeFromOptimizedCodeCache");
      Code* code = feedback_vector->optimized_code();

      if (code != nullptr) {
        // Caching of optimized code enabled and optimized code found.
        DCHECK(!code->marked_for_deoptimization());
        DCHECK(function->shared()->is_compiled());
        return Handle<Code>(code);
      }
    }
  }
  return MaybeHandle<Code>();
}

void ClearOptimizedCodeCache(CompilationInfo* compilation_info) {
  Handle<JSFunction> function = compilation_info->closure();
  if (compilation_info->osr_offset().IsNone()) {
    Handle<FeedbackVector> vector =
        handle(function->feedback_vector(), function->GetIsolate());
    vector->ClearOptimizedCode();
  }
}

void InsertCodeIntoOptimizedCodeCache(CompilationInfo* compilation_info) {
  Handle<Code> code = compilation_info->code();
  if (code->kind() != Code::OPTIMIZED_FUNCTION) return;  // Nothing to do.

  // Function context specialization folds-in the function context,
  // so no sharing can occur.
  if (compilation_info->is_function_context_specializing()) {
    // Native context specialized code is not shared, so make sure the optimized
    // code cache is clear.
    ClearOptimizedCodeCache(compilation_info);
    return;
  }

  // Cache optimized context-specific code.
  Handle<JSFunction> function = compilation_info->closure();
  Handle<SharedFunctionInfo> shared(function->shared());
  Handle<Context> native_context(function->context()->native_context());
  if (compilation_info->osr_offset().IsNone()) {
    Handle<FeedbackVector> vector =
        handle(function->feedback_vector(), function->GetIsolate());
    FeedbackVector::SetOptimizedCode(vector, code);
  }
}

bool GetOptimizedCodeNow(CompilationJob* job) {
  CompilationInfo* compilation_info = job->compilation_info();
  Isolate* isolate = compilation_info->isolate();
  TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
  RuntimeCallTimerScope runtimeTimer(isolate,
                                     &RuntimeCallStats::RecompileSynchronous);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
               "V8.RecompileSynchronous");

  if (job->PrepareJob() != CompilationJob::SUCCEEDED ||
      job->ExecuteJob() != CompilationJob::SUCCEEDED ||
      job->FinalizeJob() != CompilationJob::SUCCEEDED) {
    if (FLAG_trace_opt) {
      PrintF("[aborted optimizing ");
      compilation_info->closure()->ShortPrint();
      PrintF(" because: %s]\n",
             GetBailoutReason(compilation_info->bailout_reason()));
    }
    return false;
  }

  // Success!
  job->RecordOptimizedCompilationStats();
  DCHECK(!isolate->has_pending_exception());
  InsertCodeIntoOptimizedCodeCache(compilation_info);
  RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG,
                            compilation_info);
  return true;
}

bool GetOptimizedCodeLater(CompilationJob* job) {
  CompilationInfo* compilation_info = job->compilation_info();
  Isolate* isolate = compilation_info->isolate();

  if (!isolate->optimizing_compile_dispatcher()->IsQueueAvailable()) {
    if (FLAG_trace_concurrent_recompilation) {
      PrintF("  ** Compilation queue full, will retry optimizing ");
      compilation_info->closure()->ShortPrint();
      PrintF(" later.\n");
    }
    return false;
  }

  if (isolate->heap()->HighMemoryPressure()) {
    if (FLAG_trace_concurrent_recompilation) {
      PrintF("  ** High memory pressure, will retry optimizing ");
      compilation_info->closure()->ShortPrint();
      PrintF(" later.\n");
    }
    return false;
  }

  TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
  RuntimeCallTimerScope runtimeTimer(isolate,
                                     &RuntimeCallStats::RecompileSynchronous);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
               "V8.RecompileSynchronous");

  if (job->PrepareJob() != CompilationJob::SUCCEEDED) return false;
  isolate->optimizing_compile_dispatcher()->QueueForOptimization(job);

  if (FLAG_trace_concurrent_recompilation) {
    PrintF("  ** Queued ");
    compilation_info->closure()->ShortPrint();
    PrintF(" for concurrent optimization.\n");
  }
  return true;
}

MaybeHandle<Code> GetOptimizedCode(Handle<JSFunction> function,
                                   ConcurrencyMode mode,
                                   BailoutId osr_offset = BailoutId::None(),
                                   JavaScriptFrame* osr_frame = nullptr) {
  Isolate* isolate = function->GetIsolate();
  Handle<SharedFunctionInfo> shared(function->shared(), isolate);

  // Make sure we clear the optimization marker on the function so that we
  // don't try to re-optimize.
  if (function->HasOptimizationMarker()) {
    function->ClearOptimizationMarker();
  }

  Handle<Code> cached_code;
  if (GetCodeFromOptimizedCodeCache(function, osr_offset)
          .ToHandle(&cached_code)) {
    if (FLAG_trace_opt) {
      PrintF("[found optimized code for ");
      function->ShortPrint();
      if (!osr_offset.IsNone()) {
        PrintF(" at OSR AST id %d", osr_offset.ToInt());
      }
      PrintF("]\n");
    }
    return cached_code;
  }

  // Reset profiler ticks, function is no longer considered hot.
  DCHECK(shared->is_compiled());
  function->feedback_vector()->set_profiler_ticks(0);

  VMState<COMPILER> state(isolate);
  DCHECK(!isolate->has_pending_exception());
  PostponeInterruptsScope postpone(isolate);
  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, shared->HasBytecodeArray());
  std::unique_ptr<CompilationJob> job(
      compiler::Pipeline::NewCompilationJob(function, has_script));
  CompilationInfo* compilation_info = job->compilation_info();
  ParseInfo* parse_info = job->parse_info();

  compilation_info->SetOptimizingForOsr(osr_offset, osr_frame);

  // Do not use TurboFan if we need to be able to set break points.
  if (compilation_info->shared_info()->HasBreakInfo()) {
    compilation_info->AbortOptimization(kFunctionBeingDebugged);
    return MaybeHandle<Code>();
  }

  // Do not use TurboFan when %NeverOptimizeFunction was applied.
  if (shared->optimization_disabled() &&
      shared->disable_optimization_reason() == kOptimizationDisabledForTest) {
    compilation_info->AbortOptimization(kOptimizationDisabledForTest);
    return MaybeHandle<Code>();
  }

  // Do not use TurboFan if optimization is disabled or function doesn't pass
  // turbo_filter.
  if (!FLAG_opt || !shared->PassesFilter(FLAG_turbo_filter)) {
    compilation_info->AbortOptimization(kOptimizationDisabled);
    return MaybeHandle<Code>();
  }

  TimerEventScope<TimerEventOptimizeCode> optimize_code_timer(isolate);
  RuntimeCallTimerScope runtimeTimer(isolate, &RuntimeCallStats::OptimizeCode);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.OptimizeCode");

  // In case of concurrent recompilation, all handles below this point will be
  // allocated in a deferred handle scope that is detached and handed off to
  // the background thread when we return.
  base::Optional<CompilationHandleScope> compilation;
  if (mode == ConcurrencyMode::kConcurrent) {
    compilation.emplace(compilation_info);
  }

  // All handles below will be canonicalized.
  CanonicalHandleScope canonical(isolate);

  // Reopen handles in the new CompilationHandleScope.
  compilation_info->ReopenHandlesInNewHandleScope();
  parse_info->ReopenHandlesInNewHandleScope();

  if (mode == ConcurrencyMode::kConcurrent) {
    if (GetOptimizedCodeLater(job.get())) {
      job.release();  // The background recompile job owns this now.

      // Set the optimization marker and return a code object which checks it.
      function->SetOptimizationMarker(OptimizationMarker::kInOptimizationQueue);
      if (function->IsInterpreted()) {
        return BUILTIN_CODE(isolate, InterpreterEntryTrampoline);
      } else {
        return BUILTIN_CODE(isolate, CheckOptimizationMarker);
      }
    }
  } else {
    if (GetOptimizedCodeNow(job.get())) return compilation_info->code();
  }

  if (isolate->has_pending_exception()) isolate->clear_pending_exception();
  return MaybeHandle<Code>();
}

CompilationJob::Status FinalizeOptimizedCompilationJob(CompilationJob* job) {
  CompilationInfo* compilation_info = job->compilation_info();
  Isolate* isolate = compilation_info->isolate();

  TimerEventScope<TimerEventRecompileSynchronous> timer(isolate);
  RuntimeCallTimerScope runtimeTimer(isolate,
                                     &RuntimeCallStats::RecompileSynchronous);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
               "V8.RecompileSynchronous");

  Handle<SharedFunctionInfo> shared = compilation_info->shared_info();

  // Reset profiler ticks, function is no longer considered hot.
  compilation_info->closure()->feedback_vector()->set_profiler_ticks(0);

  DCHECK(!shared->HasBreakInfo());

  // 1) Optimization on the concurrent thread may have failed.
  // 2) The function may have already been optimized by OSR.  Simply continue.
  //    Except when OSR already disabled optimization for some reason.
  // 3) The code may have already been invalidated due to dependency change.
  // 4) Code generation may have failed.
  if (job->state() == CompilationJob::State::kReadyToFinalize) {
    if (shared->optimization_disabled()) {
      job->RetryOptimization(kOptimizationDisabled);
    } else if (compilation_info->dependencies()->HasAborted()) {
      job->RetryOptimization(kBailedOutDueToDependencyChange);
    } else if (job->FinalizeJob() == CompilationJob::SUCCEEDED) {
      job->RecordOptimizedCompilationStats();
      RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG,
                                compilation_info);
      InsertCodeIntoOptimizedCodeCache(compilation_info);
      if (FLAG_trace_opt) {
        PrintF("[completed optimizing ");
        compilation_info->closure()->ShortPrint();
        PrintF("]\n");
      }
      compilation_info->closure()->ReplaceCode(*compilation_info->code());
      return CompilationJob::SUCCEEDED;
    }
  }

  DCHECK(job->state() == CompilationJob::State::kFailed);
  if (FLAG_trace_opt) {
    PrintF("[aborted optimizing ");
    compilation_info->closure()->ShortPrint();
    PrintF(" because: %s]\n",
           GetBailoutReason(compilation_info->bailout_reason()));
  }
  compilation_info->closure()->ReplaceCode(shared->code());
  // Clear the InOptimizationQueue marker, if it exists.
  if (compilation_info->closure()->IsInOptimizationQueue()) {
    compilation_info->closure()->ClearOptimizationMarker();
  }
  return CompilationJob::FAILED;
}

MaybeHandle<SharedFunctionInfo> CompileToplevel(ParseInfo* parse_info,
                                                Isolate* isolate) {
  TimerEventScope<TimerEventCompileCode> top_level_timer(isolate);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileCode");
  PostponeInterruptsScope postpone(isolate);
  DCHECK(!isolate->native_context().is_null());
  RuntimeCallTimerScope runtimeTimer(
      isolate, parse_info->is_eval() ? &RuntimeCallStats::CompileEval
                                     : &RuntimeCallStats::CompileScript);

  Handle<Script> script = parse_info->script();
  Handle<SharedFunctionInfo> result;
  VMState<BYTECODE_COMPILER> state(isolate);
  if (parse_info->literal() == nullptr &&
      !parsing::ParseProgram(parse_info, isolate)) {
    return MaybeHandle<SharedFunctionInfo>();
  }
  // Measure how long it takes to do the compilation; only take the
  // rest of the function into account to avoid overlap with the
  // parsing statistics.
  HistogramTimer* rate = parse_info->is_eval()
                             ? isolate->counters()->compile_eval()
                             : isolate->counters()->compile();
  HistogramTimerScope timer(rate);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
               parse_info->is_eval() ? "V8.CompileEval" : "V8.Compile");

  // Generate the unoptimized bytecode or asm-js data.
  std::forward_list<std::unique_ptr<CompilationJob>> inner_function_jobs;
  std::unique_ptr<CompilationJob> outer_function_job(
      GenerateUnoptimizedCode(parse_info, isolate, &inner_function_jobs));
  if (!outer_function_job) {
    if (!isolate->has_pending_exception()) isolate->StackOverflow();
    return MaybeHandle<SharedFunctionInfo>();
  }

  // Internalize ast values onto the heap.
  parse_info->ast_value_factory()->Internalize(isolate);

  // Create shared function infos for top level and shared function infos array
  // for inner functions.
  EnsureSharedFunctionInfosArrayOnScript(parse_info, isolate);
  DCHECK_EQ(kNoSourcePosition,
            parse_info->literal()->function_token_position());
  Handle<SharedFunctionInfo> shared_info =
      isolate->factory()->NewSharedFunctionInfoForLiteral(parse_info->literal(),
                                                          parse_info->script());
  shared_info->set_is_toplevel(true);

  // Finalize compilation of the unoptimized bytecode or asm-js data.
  if (!FinalizeUnoptimizedCode(parse_info, isolate, shared_info,
                               outer_function_job.get(),
                               &inner_function_jobs)) {
    if (!isolate->has_pending_exception()) isolate->StackOverflow();
    return MaybeHandle<SharedFunctionInfo>();
  }

  if (!script.is_null()) {
    script->set_compilation_state(Script::COMPILATION_STATE_COMPILED);
  }

  return shared_info;
}

bool FailWithPendingException(Isolate* isolate,
                              Compiler::ClearExceptionFlag flag) {
  if (flag == Compiler::CLEAR_EXCEPTION) {
    isolate->clear_pending_exception();
  } else if (!isolate->has_pending_exception()) {
    isolate->StackOverflow();
  }
  return false;
}

}  // namespace

// ----------------------------------------------------------------------------
// Implementation of Compiler

bool Compiler::Analyze(ParseInfo* parse_info,
                       EagerInnerFunctionLiterals* eager_literals) {
  DCHECK_NOT_NULL(parse_info->literal());
  RuntimeCallTimerScope runtimeTimer(parse_info->runtime_call_stats(),
                                     &RuntimeCallStats::CompileAnalyse);
  if (!Rewriter::Rewrite(parse_info)) return false;
  DeclarationScope::Analyze(parse_info);
  if (!Renumber(parse_info, eager_literals)) return false;
  return true;
}

bool Compiler::ParseAndAnalyze(ParseInfo* parse_info,
                               Handle<SharedFunctionInfo> shared_info,
                               Isolate* isolate) {
  if (!parsing::ParseAny(parse_info, shared_info, isolate)) {
    return false;
  }
  return Compiler::Analyze(parse_info);
}

bool Compiler::Compile(Handle<SharedFunctionInfo> shared_info,
                       ClearExceptionFlag flag) {
  // We should never reach here if the function is already compiled.
  DCHECK(!shared_info->is_compiled());

  Isolate* isolate = shared_info->GetIsolate();
  DCHECK(!isolate->has_pending_exception());
  DCHECK(!shared_info->HasBytecodeArray());
  VMState<BYTECODE_COMPILER> state(isolate);
  PostponeInterruptsScope postpone(isolate);
  TimerEventScope<TimerEventCompileCode> compile_timer(isolate);
  RuntimeCallTimerScope runtimeTimer(isolate,
                                     &RuntimeCallStats::CompileFunction);
  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"), "V8.CompileCode");
  AggregatedHistogramTimerScope timer(isolate->counters()->compile_lazy());

  // Check if the compiler dispatcher has shared_info enqueued for compile.
  CompilerDispatcher* dispatcher = isolate->compiler_dispatcher();
  if (dispatcher->IsEnqueued(shared_info)) {
    if (!dispatcher->FinishNow(shared_info)) {
      return FailWithPendingException(isolate, flag);
    }
    return true;
  }

  // Set up parse info.
  ParseInfo parse_info(shared_info);
  parse_info.set_lazy_compile();
  if (FLAG_preparser_scope_analysis) {
    if (shared_info->HasPreParsedScopeData()) {
      Handle<PreParsedScopeData> data(
          PreParsedScopeData::cast(shared_info->preparsed_scope_data()));
      parse_info.consumed_preparsed_scope_data()->SetData(data);
      // After we've compiled the function, we don't need data about its
      // skippable functions any more.
      shared_info->set_preparsed_scope_data(isolate->heap()->null_value());
    }
  }

  // Parse and update ParseInfo with the results.
  if (!parsing::ParseFunction(&parse_info, shared_info, isolate)) {
    return FailWithPendingException(isolate, flag);
  }

  // Generate the unoptimized bytecode or asm-js data.
  std::forward_list<std::unique_ptr<CompilationJob>> inner_function_jobs;
  std::unique_ptr<CompilationJob> outer_function_job(
      GenerateUnoptimizedCode(&parse_info, isolate, &inner_function_jobs));
  if (!outer_function_job) {
    return FailWithPendingException(isolate, flag);
  }

  // Internalize ast values onto the heap.
  parse_info.ast_value_factory()->Internalize(isolate);

  // Finalize compilation of the unoptimized bytecode or asm-js data.
  if (!FinalizeUnoptimizedCode(&parse_info, isolate, shared_info,
                               outer_function_job.get(),
                               &inner_function_jobs)) {
    return FailWithPendingException(isolate, flag);
  }

  DCHECK(!isolate->has_pending_exception());
  return true;
}

bool Compiler::Compile(Handle<JSFunction> function, ClearExceptionFlag flag) {
  // We should never reach here if the function is already compiled or optimized
  DCHECK(!function->is_compiled());
  DCHECK(!function->IsOptimized());
  DCHECK(!function->HasOptimizationMarker());
  DCHECK(!function->HasOptimizedCode());

  Isolate* isolate = function->GetIsolate();
  Handle<SharedFunctionInfo> shared_info = handle(function->shared());
  DCHECK(AllowCompilation::IsAllowed(isolate));

  // Ensure shared function info is compiled.
  if (!shared_info->is_compiled() && !Compile(shared_info, flag)) return false;
  Handle<Code> code = handle(shared_info->code(), isolate);

  // Allocate literals for the JSFunction.
  JSFunction::EnsureLiterals(function);

  // Optimize now if --always-opt is enabled.
  if (FLAG_always_opt && !function->shared()->HasAsmWasmData()) {
    if (FLAG_trace_opt) {
      PrintF("[optimizing ");
      function->ShortPrint();
      PrintF(" because --always-opt]\n");
    }
    Handle<Code> opt_code;
    if (GetOptimizedCode(function, ConcurrencyMode::kNotConcurrent)
            .ToHandle(&opt_code)) {
      code = opt_code;
    }
  }

  // Install code on closure.
  function->ReplaceCode(*code);

  // Check postconditions on success.
  DCHECK(!isolate->has_pending_exception());
  DCHECK(function->shared()->is_compiled());
  DCHECK(function->is_compiled());
  return true;
}

bool Compiler::CompileOptimized(Handle<JSFunction> function,
                                ConcurrencyMode mode) {
  if (function->IsOptimized()) return true;
  Isolate* isolate = function->GetIsolate();
  DCHECK(AllowCompilation::IsAllowed(isolate));

  // Start a compilation.
  Handle<Code> code;
  if (!GetOptimizedCode(function, mode).ToHandle(&code)) {
    // Optimization failed, get unoptimized code. Unoptimized code must exist
    // already if we are optimizing.
    DCHECK(!isolate->has_pending_exception());
    DCHECK(function->shared()->is_compiled());
    code = handle(function->shared()->code(), isolate);
  }

  // Install code on closure.
  function->ReplaceCode(*code);

  // Check postconditions on success.
  DCHECK(!isolate->has_pending_exception());
  DCHECK(function->shared()->is_compiled());
  DCHECK(function->is_compiled());
  DCHECK_IMPLIES(function->HasOptimizationMarker(),
                 function->IsInOptimizationQueue());
  DCHECK_IMPLIES(function->HasOptimizationMarker(),
                 function->ChecksOptimizationMarker());
  DCHECK_IMPLIES(function->IsInOptimizationQueue(),
                 mode == ConcurrencyMode::kConcurrent);
  return true;
}

MaybeHandle<JSArray> Compiler::CompileForLiveEdit(Handle<Script> script) {
  Isolate* isolate = script->GetIsolate();
  DCHECK(AllowCompilation::IsAllowed(isolate));

  // In order to ensure that live edit function info collection finds the newly
  // generated shared function infos, clear the script's list temporarily
  // and restore it at the end of this method.
  Handle<FixedArray> old_function_infos(script->shared_function_infos(),
                                        isolate);
  script->set_shared_function_infos(isolate->heap()->empty_fixed_array());

  // Start a compilation.
  ParseInfo parse_info(script);
  parse_info.set_is_debug();

  // TODO(635): support extensions.
  Handle<JSArray> infos;
  Handle<SharedFunctionInfo> shared_info;
  if (CompileToplevel(&parse_info, isolate).ToHandle(&shared_info)) {
    // Check postconditions on success.
    DCHECK(!isolate->has_pending_exception());
    infos = LiveEditFunctionTracker::Collect(parse_info.literal(), script,
                                             parse_info.zone(), isolate);
  }

  // Restore the original function info list in order to remain side-effect
  // free as much as possible, since some code expects the old shared function
  // infos to stick around.
  script->set_shared_function_infos(*old_function_infos);

  return infos;
}

MaybeHandle<JSFunction> Compiler::GetFunctionFromEval(
    Handle<String> source, Handle<SharedFunctionInfo> outer_info,
    Handle<Context> context, LanguageMode language_mode,
    ParseRestriction restriction, int parameters_end_pos,
    int eval_scope_position, int eval_position, int line_offset,
    int column_offset, Handle<Object> script_name,
    ScriptOriginOptions options) {
  Isolate* isolate = source->GetIsolate();
  int source_length = source->length();
  isolate->counters()->total_eval_size()->Increment(source_length);
  isolate->counters()->total_compile_size()->Increment(source_length);

  // The cache lookup key needs to be aware of the separation between the
  // parameters and the body to prevent this valid invocation:
  //   Function("", "function anonymous(\n/**/) {\n}");
  // from adding an entry that falsely approves this invalid invocation:
  //   Function("\n/**/) {\nfunction anonymous(", "}");
  // The actual eval_scope_position for indirect eval and CreateDynamicFunction
  // is unused (just 0), which means it's an available field to use to indicate
  // this separation. But to make sure we're not causing other false hits, we
  // negate the scope position.
  int position = eval_scope_position;
  if (FLAG_harmony_function_tostring &&
      restriction == ONLY_SINGLE_FUNCTION_LITERAL &&
      parameters_end_pos != kNoSourcePosition) {
    // use the parameters_end_pos as the eval_scope_position in the eval cache.
    DCHECK_EQ(eval_scope_position, 0);
    position = -parameters_end_pos;
  }
  CompilationCache* compilation_cache = isolate->compilation_cache();
  InfoVectorPair eval_result = compilation_cache->LookupEval(
      source, outer_info, context, language_mode, position);
  Handle<Cell> vector;
  if (eval_result.has_vector()) {
    vector = Handle<Cell>(eval_result.vector(), isolate);
  }

  Handle<SharedFunctionInfo> shared_info;
  Handle<Script> script;
  if (eval_result.has_shared()) {
    shared_info = Handle<SharedFunctionInfo>(eval_result.shared(), isolate);
    script = Handle<Script>(Script::cast(shared_info->script()), isolate);
  } else {
    script = isolate->factory()->NewScript(source);
    if (isolate->NeedsSourcePositionsForProfiling()) {
      Script::InitLineEnds(script);
    }
    if (!script_name.is_null()) {
      script->set_name(*script_name);
      script->set_line_offset(line_offset);
      script->set_column_offset(column_offset);
    }
    script->set_origin_options(options);
    script->set_compilation_type(Script::COMPILATION_TYPE_EVAL);

    script->set_eval_from_shared(*outer_info);
    if (eval_position == kNoSourcePosition) {
      // If the position is missing, attempt to get the code offset by
      // walking the stack. Do not translate the code offset into source
      // position, but store it as negative value for lazy translation.
      StackTraceFrameIterator it(script->GetIsolate());
      if (!it.done() && it.is_javascript()) {
        FrameSummary summary = FrameSummary::GetTop(it.javascript_frame());
        script->set_eval_from_shared(
            summary.AsJavaScript().function()->shared());
        eval_position = -summary.code_offset();
      } else {
        eval_position = 0;
      }
    }
    script->set_eval_from_position(eval_position);

    ParseInfo parse_info(script);
    parse_info.set_eval();
    parse_info.set_language_mode(language_mode);
    parse_info.set_parse_restriction(restriction);
    parse_info.set_parameters_end_pos(parameters_end_pos);
    if (!context->IsNativeContext()) {
      parse_info.set_outer_scope_info(handle(context->scope_info()));
    }

    if (!CompileToplevel(&parse_info, isolate).ToHandle(&shared_info)) {
      return MaybeHandle<JSFunction>();
    }
  }

  // If caller is strict mode, the result must be in strict mode as well.
  DCHECK(is_sloppy(language_mode) || is_strict(shared_info->language_mode()));

  Handle<JSFunction> result;
  if (eval_result.has_shared()) {
    if (eval_result.has_vector()) {
      result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
          shared_info, context, vector, NOT_TENURED);
    } else {
      result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
          shared_info, context, NOT_TENURED);
      JSFunction::EnsureLiterals(result);
      // Make sure to cache this result.
      Handle<Cell> new_vector(result->feedback_vector_cell(), isolate);
      compilation_cache->PutEval(source, outer_info, context, shared_info,
                                 new_vector, eval_scope_position);
    }
  } else {
    result = isolate->factory()->NewFunctionFromSharedFunctionInfo(
        shared_info, context, NOT_TENURED);
    JSFunction::EnsureLiterals(result);
    // Add the SharedFunctionInfo and the LiteralsArray to the eval cache if
    // we didn't retrieve from there.
    Handle<Cell> vector(result->feedback_vector_cell(), isolate);
    compilation_cache->PutEval(source, outer_info, context, shared_info, vector,
                               eval_scope_position);
  }

  // OnAfterCompile has to be called after we create the JSFunction, which we
  // may require to recompile the eval for debugging, if we find a function
  // that contains break points in the eval script.
  isolate->debug()->OnAfterCompile(script);

  return result;
}

namespace {

bool ContainsAsmModule(Handle<Script> script) {
  DisallowHeapAllocation no_gc;
  SharedFunctionInfo::ScriptIterator iter(script);
  while (SharedFunctionInfo* info = iter.Next()) {
    if (info->HasAsmWasmData()) return true;
  }
  return false;
}

}  // namespace

bool Compiler::CodeGenerationFromStringsAllowed(Isolate* isolate,
                                                Handle<Context> context,
                                                Handle<String> source) {
  DCHECK(context->allow_code_gen_from_strings()->IsFalse(isolate));
  // Check with callback if set.
  AllowCodeGenerationFromStringsCallback callback =
      isolate->allow_code_gen_callback();
  if (callback == NULL) {
    // No callback set and code generation disallowed.
    return false;
  } else {
    // Callback set. Let it decide if code generation is allowed.
    VMState<EXTERNAL> state(isolate);
    return callback(v8::Utils::ToLocal(context), v8::Utils::ToLocal(source));
  }
}

MaybeHandle<JSFunction> Compiler::GetFunctionFromString(
    Handle<Context> context, Handle<String> source,
    ParseRestriction restriction, int parameters_end_pos) {
  Isolate* const isolate = context->GetIsolate();
  Handle<Context> native_context(context->native_context(), isolate);

  // Check if native context allows code generation from
  // strings. Throw an exception if it doesn't.
  if (native_context->allow_code_gen_from_strings()->IsFalse(isolate) &&
      !CodeGenerationFromStringsAllowed(isolate, native_context, source)) {
    Handle<Object> error_message =
        native_context->ErrorMessageForCodeGenerationFromStrings();
    THROW_NEW_ERROR(isolate, NewEvalError(MessageTemplate::kCodeGenFromStrings,
                                          error_message),
                    JSFunction);
  }

  // Compile source string in the native context.
  int eval_scope_position = 0;
  int eval_position = kNoSourcePosition;
  Handle<SharedFunctionInfo> outer_info(native_context->closure()->shared());
  return Compiler::GetFunctionFromEval(source, outer_info, native_context,
                                       SLOPPY, restriction, parameters_end_pos,
                                       eval_scope_position, eval_position);
}

Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForScript(
    Handle<String> source, Handle<Object> script_name, int line_offset,
    int column_offset, ScriptOriginOptions resource_options,
    Handle<Object> source_map_url, Handle<Context> context,
    v8::Extension* extension, ScriptData** cached_data,
    ScriptCompiler::CompileOptions compile_options, NativesFlag natives,
    Handle<FixedArray> host_defined_options) {
  Isolate* isolate = source->GetIsolate();
  if (compile_options == ScriptCompiler::kNoCompileOptions) {
    cached_data = NULL;
  } else if (compile_options == ScriptCompiler::kProduceParserCache ||
             compile_options == ScriptCompiler::kProduceCodeCache) {
    DCHECK(cached_data && !*cached_data);
    DCHECK(extension == NULL);
    DCHECK(!isolate->debug()->is_loaded());
  } else {
    DCHECK(compile_options == ScriptCompiler::kConsumeParserCache ||
           compile_options == ScriptCompiler::kConsumeCodeCache);
    DCHECK(cached_data && *cached_data);
    DCHECK(extension == NULL);
  }
  int source_length = source->length();
  isolate->counters()->total_load_size()->Increment(source_length);
  isolate->counters()->total_compile_size()->Increment(source_length);

  LanguageMode language_mode = construct_language_mode(FLAG_use_strict);
  CompilationCache* compilation_cache = isolate->compilation_cache();

  // Do a lookup in the compilation cache but not for extensions.
  Handle<SharedFunctionInfo> result;
  Handle<Cell> vector;
  if (extension == NULL) {
    // First check per-isolate compilation cache.
    InfoVectorPair pair = compilation_cache->LookupScript(
        source, script_name, line_offset, column_offset, resource_options,
        context, language_mode);
    if (!pair.has_shared() && FLAG_serialize_toplevel &&
        compile_options == ScriptCompiler::kConsumeCodeCache &&
        !isolate->debug()->is_loaded()) {
      // Then check cached code provided by embedder.
      HistogramTimerScope timer(isolate->counters()->compile_deserialize());
      RuntimeCallTimerScope runtimeTimer(isolate,
                                         &RuntimeCallStats::CompileDeserialize);
      TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                   "V8.CompileDeserialize");
      Handle<SharedFunctionInfo> inner_result;
      if (CodeSerializer::Deserialize(isolate, *cached_data, source)
              .ToHandle(&inner_result)) {
        // Promote to per-isolate compilation cache.
        DCHECK(inner_result->is_compiled());
        Handle<FeedbackVector> feedback_vector =
            FeedbackVector::New(isolate, inner_result);
        vector = isolate->factory()->NewCell(feedback_vector);
        compilation_cache->PutScript(source, context, language_mode,
                                     inner_result, vector);
        Handle<Script> script(Script::cast(inner_result->script()), isolate);
        isolate->debug()->OnAfterCompile(script);
        return inner_result;
      }
      // Deserializer failed. Fall through to compile.
    } else {
      if (pair.has_shared()) {
        result = Handle<SharedFunctionInfo>(pair.shared(), isolate);
      }
      if (pair.has_vector()) {
        vector = Handle<Cell>(pair.vector(), isolate);
      }
    }
  }

  base::ElapsedTimer timer;
  if (FLAG_profile_deserialization && FLAG_serialize_toplevel &&
      compile_options == ScriptCompiler::kProduceCodeCache) {
    timer.Start();
  }

  if (result.is_null() ||
      (FLAG_serialize_toplevel &&
       compile_options == ScriptCompiler::kProduceCodeCache)) {
    // No cache entry found, or embedder wants a code cache. Compile the script.

    // Create a script object describing the script to be compiled.
    Handle<Script> script = isolate->factory()->NewScript(source);
    if (isolate->NeedsSourcePositionsForProfiling()) {
      Script::InitLineEnds(script);
    }
    if (natives == NATIVES_CODE) {
      script->set_type(Script::TYPE_NATIVE);
    } else if (natives == EXTENSION_CODE) {
      script->set_type(Script::TYPE_EXTENSION);
    } else if (natives == INSPECTOR_CODE) {
      script->set_type(Script::TYPE_INSPECTOR);
    }
    if (!script_name.is_null()) {
      script->set_name(*script_name);
      script->set_line_offset(line_offset);
      script->set_column_offset(column_offset);
    }
    script->set_origin_options(resource_options);
    if (!source_map_url.is_null()) {
      script->set_source_mapping_url(*source_map_url);
    }
    if (!host_defined_options.is_null()) {
      script->set_host_defined_options(*host_defined_options);
    }

    // Compile the function and add it to the cache.
    ParseInfo parse_info(script);
    Zone compile_zone(isolate->allocator(), ZONE_NAME);
    if (resource_options.IsModule()) parse_info.set_module();
    if (compile_options != ScriptCompiler::kNoCompileOptions) {
      parse_info.set_cached_data(cached_data);
    }
    parse_info.set_compile_options(compile_options);
    parse_info.set_extension(extension);
    if (!context->IsNativeContext()) {
      parse_info.set_outer_scope_info(handle(context->scope_info()));
    }
    if (FLAG_serialize_toplevel &&
        compile_options == ScriptCompiler::kProduceCodeCache) {
      parse_info.set_will_serialize();
    }

    parse_info.set_language_mode(
        static_cast<LanguageMode>(parse_info.language_mode() | language_mode));
    CompileToplevel(&parse_info, isolate).ToHandle(&result);
    if (extension == NULL && !result.is_null()) {
      // We need a feedback vector.
      DCHECK(result->is_compiled());
      Handle<FeedbackVector> feedback_vector =
          FeedbackVector::New(isolate, result);
      vector = isolate->factory()->NewCell(feedback_vector);
      compilation_cache->PutScript(source, context, language_mode, result,
                                   vector);
      if (FLAG_serialize_toplevel &&
          compile_options == ScriptCompiler::kProduceCodeCache &&
          !ContainsAsmModule(script)) {
        HistogramTimerScope histogram_timer(
            isolate->counters()->compile_serialize());
        RuntimeCallTimerScope runtimeTimer(isolate,
                                           &RuntimeCallStats::CompileSerialize);
        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                     "V8.CompileSerialize");
        *cached_data = CodeSerializer::Serialize(isolate, result, source);
        if (FLAG_profile_deserialization) {
          PrintF("[Compiling and serializing took %0.3f ms]\n",
                 timer.Elapsed().InMillisecondsF());
        }
      }
    }

    if (result.is_null()) {
      if (natives != EXTENSION_CODE && natives != NATIVES_CODE) {
        isolate->ReportPendingMessages();
      }
    } else {
      isolate->debug()->OnAfterCompile(script);
    }
  }
  return result;
}

Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForStreamedScript(
    Handle<Script> script, ParseInfo* parse_info, int source_length) {
  Isolate* isolate = script->GetIsolate();
  // TODO(titzer): increment the counters in caller.
  isolate->counters()->total_load_size()->Increment(source_length);
  isolate->counters()->total_compile_size()->Increment(source_length);

  LanguageMode language_mode = construct_language_mode(FLAG_use_strict);
  parse_info->set_language_mode(
      static_cast<LanguageMode>(parse_info->language_mode() | language_mode));

  Handle<SharedFunctionInfo> result;
  if (CompileToplevel(parse_info, isolate).ToHandle(&result)) {
    isolate->debug()->OnAfterCompile(script);
  }
  return result;
}

Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
    FunctionLiteral* literal, Handle<Script> script, Isolate* isolate) {
  // Precondition: code has been parsed and scopes have been analyzed.
  MaybeHandle<SharedFunctionInfo> maybe_existing;

  // Find any previously allocated shared function info for the given literal.
  maybe_existing = script->FindSharedFunctionInfo(isolate, literal);

  // If we found an existing shared function info, return it.
  Handle<SharedFunctionInfo> existing;
  if (maybe_existing.ToHandle(&existing)) {
    DCHECK(!existing->is_toplevel());
    return existing;
  }

  // Allocate a shared function info object which will be compiled lazily.
  Handle<SharedFunctionInfo> result =
      isolate->factory()->NewSharedFunctionInfoForLiteral(literal, script);
  result->set_is_toplevel(false);
  Scope* outer_scope = literal->scope()->GetOuterScopeWithContext();
  if (outer_scope) {
    result->set_outer_scope_info(*outer_scope->scope_info());
  }
  return result;
}

Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForNative(
    v8::Extension* extension, Handle<String> name) {
  Isolate* isolate = name->GetIsolate();
  v8::Isolate* v8_isolate = reinterpret_cast<v8::Isolate*>(isolate);

  // Compute the function template for the native function.
  v8::Local<v8::FunctionTemplate> fun_template =
      extension->GetNativeFunctionTemplate(v8_isolate,
                                           v8::Utils::ToLocal(name));
  DCHECK(!fun_template.IsEmpty());

  // Instantiate the function and create a shared function info from it.
  Handle<JSFunction> fun = Handle<JSFunction>::cast(Utils::OpenHandle(
      *fun_template->GetFunction(v8_isolate->GetCurrentContext())
           .ToLocalChecked()));
  Handle<Code> code = Handle<Code>(fun->shared()->code());
  Handle<Code> construct_stub = Handle<Code>(fun->shared()->construct_stub());
  Handle<SharedFunctionInfo> shared = isolate->factory()->NewSharedFunctionInfo(
      name, FunctionKind::kNormalFunction, code,
      Handle<ScopeInfo>(fun->shared()->scope_info()));
  shared->set_outer_scope_info(fun->shared()->outer_scope_info());
  shared->SetConstructStub(*construct_stub);
  shared->set_feedback_metadata(fun->shared()->feedback_metadata());

  // Copy the function data to the shared function info.
  shared->set_function_data(fun->shared()->function_data());
  int parameters = fun->shared()->internal_formal_parameter_count();
  shared->set_internal_formal_parameter_count(parameters);

  return shared;
}

MaybeHandle<Code> Compiler::GetOptimizedCodeForOSR(Handle<JSFunction> function,
                                                   BailoutId osr_offset,
                                                   JavaScriptFrame* osr_frame) {
  DCHECK(!osr_offset.IsNone());
  DCHECK_NOT_NULL(osr_frame);
  return GetOptimizedCode(function, ConcurrencyMode::kNotConcurrent, osr_offset,
                          osr_frame);
}

CompilationJob* Compiler::PrepareUnoptimizedCompilationJob(
    ParseInfo* parse_info, Isolate* isolate) {
  VMState<BYTECODE_COMPILER> state(isolate);
  std::unique_ptr<CompilationJob> job(
      interpreter::Interpreter::NewCompilationJob(
          parse_info, parse_info->literal(), isolate));
  if (job->PrepareJob() != CompilationJob::SUCCEEDED) {
    return nullptr;
  }
  return job.release();
}

bool Compiler::FinalizeCompilationJob(CompilationJob* raw_job) {
  // Take ownership of compilation job.  Deleting job also tears down the zone.
  std::unique_ptr<CompilationJob> job(raw_job);

  if (job->compilation_info()->IsOptimizing()) {
    VMState<COMPILER> state(job->compilation_info()->isolate());
    return FinalizeOptimizedCompilationJob(job.get()) ==
           CompilationJob::SUCCEEDED;
  } else {
    VMState<BYTECODE_COMPILER> state(job->compilation_info()->isolate());
    return FinalizeUnoptimizedCompilationJob(job.get()) ==
           CompilationJob::SUCCEEDED;
  }
}

void Compiler::PostInstantiation(Handle<JSFunction> function,
                                 PretenureFlag pretenure) {
  Handle<SharedFunctionInfo> shared(function->shared());

  if (FLAG_always_opt && shared->allows_lazy_compilation() &&
      !shared->optimization_disabled() && !shared->HasAsmWasmData() &&
      shared->is_compiled()) {
    // TODO(mvstanton): pass pretenure flag to EnsureLiterals.
    JSFunction::EnsureLiterals(function);

    if (!function->IsOptimized()) {
      // Only mark for optimization if we don't already have optimized code.
      if (!function->HasOptimizedCode()) {
        function->MarkForOptimization(ConcurrencyMode::kNotConcurrent);
      }
    }
  }

  if (shared->is_compiled()) {
    // TODO(mvstanton): pass pretenure flag to EnsureLiterals.
    JSFunction::EnsureLiterals(function);

    Code* code = function->feedback_vector()->optimized_code();
    if (code != nullptr) {
      // Caching of optimized code enabled and optimized code found.
      DCHECK(!code->marked_for_deoptimization());
      DCHECK(function->shared()->is_compiled());
      function->ReplaceCode(code);
    }
  }
}

}  // namespace internal
}  // namespace v8