[asmjs] Implement AsmJsCompilationJob.

Moves AsmJs compilation into an AsmJs compilation job. This enables it
to be treated like other unoptimized compilations and avoids some
special-casing in compiler.cc.

BUG=v8:5203

Change-Id: I71ad27e3f72815b4c4074634fff0d168a9c89102
Reviewed-on: https://chromium-review.googlesource.com/581487Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46863}

src/asmjs/asm-js.cc

@@ -10,6 +10,7 @@
 #include "src/ast/ast.h"
 #include "src/base/platform/elapsed-timer.h"
 #include "src/compilation-info.h"
+#include "src/compiler.h"
 #include "src/execution.h"
 #include "src/factory.h"
 #include "src/handles.h"
@@ -166,91 +167,131 @@ void ReportInstantiationFailure(Handle<Script> script, int position,
 
 }  // namespace
 
-MaybeHandle<FixedArray> AsmJs::CompileAsmViaWasm(CompilationInfo* info) {
-  wasm::ZoneBuffer* module = nullptr;
-  wasm::ZoneBuffer* asm_offsets = nullptr;
-  Handle<FixedArray> uses_array;
-  Handle<WasmModuleObject> compiled;
-
-  // The compilation of asm.js modules is split into two distinct steps:
-  //  [1] The asm.js module source is parsed, validated, and translated to a
-  //      valid WebAssembly module. The result are two vectors representing the
-  //      encoded module as well as encoded source position information.
-  //  [2] The module is handed to WebAssembly which decodes it into an internal
-  //      representation and eventually compiles it to machine code.
-  double translate_time;  // Time (milliseconds) taken to execute step [1].
-  double compile_time;    // Time (milliseconds) taken to execute step [2].
+// The compilation of asm.js modules is split into two distinct steps:
+//  [1] PrepareJobImpl: The asm.js module source is parsed, validated, and
+//      translated to a valid WebAssembly module. The result are two vectors
+//      representing the encoded module as well as encoded source position
+//      information and a StdlibSet.
+//  [2] FinalizeJobImp: The module is handed to WebAssembly which decodes it
+//      into an internal representation and eventually compiles it to machine
+//      code.
+class AsmJsCompilationJob final : public CompilationJob {
+ public:
+  explicit AsmJsCompilationJob(CompilationInfo* info)
+      : CompilationJob(info->isolate(), info, "AsmJs"),
+        module_(nullptr),
+        asm_offsets_(nullptr),
+        translate_time_(0),
+        compile_time_(0) {}
 
+ protected:
+  Status PrepareJobImpl() final;
+  Status ExecuteJobImpl() final;
+  Status FinalizeJobImpl() final;
+
+ private:
+  wasm::ZoneBuffer* module_;
+  wasm::ZoneBuffer* asm_offsets_;
+  // TODO(mstarzinger) Replace with a bitvector.
+  wasm::AsmJsParser::StdlibSet stdlib_uses_;
+
+  double translate_time_;  // Time (milliseconds) taken to execute step [1].
+  double compile_time_;    // Time (milliseconds) taken to execute step [2].
+
+  DISALLOW_COPY_AND_ASSIGN(AsmJsCompilationJob);
+};
+
+CompilationJob::Status AsmJsCompilationJob::PrepareJobImpl() {
   // Step 1: Translate asm.js module to WebAssembly module.
-  {
-    HistogramTimerScope translate_time_scope(
-        info->isolate()->counters()->asm_wasm_translation_time());
-    size_t compile_zone_start = info->zone()->allocation_size();
-    base::ElapsedTimer translate_timer;
-    translate_timer.Start();
-
-    Zone* compile_zone = info->zone();
-    Zone translate_zone(info->isolate()->allocator(), ZONE_NAME);
-    std::unique_ptr<Utf16CharacterStream> stream(ScannerStream::For(
-        handle(String::cast(info->script()->source())),
-        info->literal()->start_position(), info->literal()->end_position()));
-    uintptr_t stack_limit = info->isolate()->stack_guard()->real_climit();
-    wasm::AsmJsParser parser(&translate_zone, stack_limit, std::move(stream));
-    if (!parser.Run()) {
-      DCHECK(!info->isolate()->has_pending_exception());
-      ReportCompilationFailure(info->script(), parser.failure_location(),
-                               parser.failure_message());
-      return MaybeHandle<FixedArray>();
-    }
-    module = new (compile_zone) wasm::ZoneBuffer(compile_zone);
-    parser.module_builder()->WriteTo(*module);
-    asm_offsets = new (compile_zone) wasm::ZoneBuffer(compile_zone);
-    parser.module_builder()->WriteAsmJsOffsetTable(*asm_offsets);
-    uses_array = info->isolate()->factory()->NewFixedArray(
-        static_cast<int>(parser.stdlib_uses()->size()));
-    int count = 0;
-    for (auto i : *parser.stdlib_uses()) {
-      uses_array->set(count++, Smi::FromInt(i));
-    }
-    size_t compile_zone_size =
-        info->zone()->allocation_size() - compile_zone_start;
-    size_t translate_zone_size = translate_zone.allocation_size();
-    info->isolate()
-        ->counters()
-        ->asm_wasm_translation_peak_memory_bytes()
-        ->AddSample(static_cast<int>(translate_zone_size));
-    translate_time = translate_timer.Elapsed().InMillisecondsF();
-    if (FLAG_trace_asm_parser) {
-      PrintF(
-          "[asm.js translation successful: time=%0.3fms, "
-          "translate_zone=%" PRIuS "KB, compile_zone+=%" PRIuS "KB]\n",
-          translate_time, translate_zone_size / KB, compile_zone_size / KB);
-    }
+  HistogramTimerScope translate_time_scope(
+      info()->isolate()->counters()->asm_wasm_translation_time());
+  size_t compile_zone_start = info()->zone()->allocation_size();
+  base::ElapsedTimer translate_timer;
+  translate_timer.Start();
+
+  Zone* compile_zone = info()->zone();
+  Zone translate_zone(info()->isolate()->allocator(), ZONE_NAME);
+
+  // TODO(mstarzinger): In order to move translation to the non-main thread
+  // ExecuteJob phase, the scanner stream needs to be off-heap.
+  std::unique_ptr<Utf16CharacterStream> stream(ScannerStream::For(
+      handle(String::cast(info()->script()->source())),
+      info()->literal()->start_position(), info()->literal()->end_position()));
+  wasm::AsmJsParser parser(&translate_zone, stack_limit(), std::move(stream));
+  if (!parser.Run()) {
+    DCHECK(!info()->isolate()->has_pending_exception());
+    ReportCompilationFailure(info()->script(), parser.failure_location(),
+                             parser.failure_message());
+    return FAILED;
   }
+  module_ = new (compile_zone) wasm::ZoneBuffer(compile_zone);
+  parser.module_builder()->WriteTo(*module_);
+  asm_offsets_ = new (compile_zone) wasm::ZoneBuffer(compile_zone);
+  parser.module_builder()->WriteAsmJsOffsetTable(*asm_offsets_);
+  stdlib_uses_.swap(*parser.stdlib_uses());
 
+  size_t compile_zone_size =
+      info()->zone()->allocation_size() - compile_zone_start;
+  size_t translate_zone_size = translate_zone.allocation_size();
+  info()
+      ->isolate()
+      ->counters()
+      ->asm_wasm_translation_peak_memory_bytes()
+      ->AddSample(static_cast<int>(translate_zone_size));
+  translate_time_ = translate_timer.Elapsed().InMillisecondsF();
+  if (FLAG_trace_asm_parser) {
+    PrintF(
+        "[asm.js translation successful: time=%0.3fms, "
+        "translate_zone=%" PRIuS "KB, compile_zone+=%" PRIuS "KB]\n",
+        translate_time_, translate_zone_size / KB, compile_zone_size / KB);
+  }
+  return SUCCEEDED;
+}
+
+CompilationJob::Status AsmJsCompilationJob::ExecuteJobImpl() {
+  // TODO(mstarzinger): Move translation to the Execute phase (see comment about
+  // scanner stream above.
+  return SUCCEEDED;
+}
+
+CompilationJob::Status AsmJsCompilationJob::FinalizeJobImpl() {
   // Step 2: Compile and decode the WebAssembly module.
-  {
-    base::ElapsedTimer compile_timer;
-    compile_timer.Start();
-    wasm::ErrorThrower thrower(info->isolate(), "AsmJs::Compile");
-    MaybeHandle<WasmModuleObject> maybe_compiled = SyncCompileTranslatedAsmJs(
-        info->isolate(), &thrower,
-        wasm::ModuleWireBytes(module->begin(), module->end()), info->script(),
-        Vector<const byte>(asm_offsets->begin(), asm_offsets->size()));
-    DCHECK(!maybe_compiled.is_null());
-    DCHECK(!thrower.error());
-    compile_time = compile_timer.Elapsed().InMillisecondsF();
-    compiled = maybe_compiled.ToHandleChecked();
+  base::ElapsedTimer compile_timer;
+  compile_timer.Start();
+
+  Handle<FixedArray> uses_array = info()->isolate()->factory()->NewFixedArray(
+      static_cast<int>(stdlib_uses_.size()));
+  int count = 0;
+  for (auto i : stdlib_uses_) {
+    uses_array->set(count++, Smi::FromInt(i));
   }
 
+  wasm::ErrorThrower thrower(info()->isolate(), "AsmJs::Compile");
+  Handle<WasmModuleObject> compiled =
+      SyncCompileTranslatedAsmJs(
+          info()->isolate(), &thrower,
+          wasm::ModuleWireBytes(module_->begin(), module_->end()),
+          info()->script(),
+          Vector<const byte>(asm_offsets_->begin(), asm_offsets_->size()))
+          .ToHandleChecked();
+  DCHECK(!thrower.error());
+  compile_time_ = compile_timer.Elapsed().InMillisecondsF();
+
   // The result is a compiled module and serialized standard library uses.
   Handle<FixedArray> result =
-      info->isolate()->factory()->NewFixedArray(kWasmDataEntryCount);
+      info()->isolate()->factory()->NewFixedArray(kWasmDataEntryCount);
   result->set(kWasmDataCompiledModule, *compiled);
   result->set(kWasmDataUsesArray, *uses_array);
-  ReportCompilationSuccess(info->script(), info->literal()->position(),
-                           translate_time, compile_time, module->size());
-  return result;
+  info()->SetAsmWasmData(result);
+  info()->SetCode(info()->isolate()->builtins()->InstantiateAsmJs());
+
+  ReportCompilationSuccess(info()->script(), info()->literal()->position(),
+                           translate_time_, compile_time_, module_->size());
+  return SUCCEEDED;
+}
+
+CompilationJob* AsmJs::NewCompilationJob(CompilationInfo* info) {
+  return new AsmJsCompilationJob(info);
 }
 
 MaybeHandle<Object> AsmJs::InstantiateAsmWasm(Isolate* isolate,

src/asmjs/asm-js.h

@@ -13,13 +13,14 @@ namespace v8 {
 namespace internal {
 
 class CompilationInfo;
+class CompilationJob;
 class JSArrayBuffer;
 class SharedFunctionInfo;
 
 // Interface to compile and instantiate for asm.js modules.
 class AsmJs {
  public:
-  static MaybeHandle<FixedArray> CompileAsmViaWasm(CompilationInfo* info);
+  static CompilationJob* NewCompilationJob(CompilationInfo* info);
   static MaybeHandle<Object> InstantiateAsmWasm(Isolate* isolate,
                                                 Handle<SharedFunctionInfo>,
                                                 Handle<FixedArray> wasm_data,

src/asmjs/asm-parser.h

@@ -55,7 +55,7 @@ class AsmJsParser {
   const char* failure_message() const { return failure_message_; }
   int failure_location() const { return failure_location_; }
   WasmModuleBuilder* module_builder() { return module_builder_; }
-  const StdlibSet* stdlib_uses() const { return &stdlib_uses_; }
+  StdlibSet* stdlib_uses() { return &stdlib_uses_; }
 
  private:
   // clang-format off

src/compilation-info.h

@@ -96,6 +96,9 @@ class V8_EXPORT_PRIVATE CompilationInfo final {
   bool has_bytecode_array() const { return !bytecode_array_.is_null(); }
   Handle<BytecodeArray> bytecode_array() const { return bytecode_array_; }
 
+  bool has_asm_wasm_data() const { return !asm_wasm_data_.is_null(); }
+  Handle<FixedArray> asm_wasm_data() const { return asm_wasm_data_; }
+
   bool is_calling() const {
     return GetFlag(kDeferredCalling) || GetFlag(kNonDeferredCalling);
   }
@@ -202,6 +205,10 @@ class V8_EXPORT_PRIVATE CompilationInfo final {
     bytecode_array_ = bytecode_array;
   }
 
+  void SetAsmWasmData(Handle<FixedArray> asm_wasm_data) {
+    asm_wasm_data_ = asm_wasm_data;
+  }
+
   bool ShouldTrapOnDeopt() const {
     return (FLAG_trap_on_deopt && IsOptimizing()) ||
            (FLAG_trap_on_stub_deopt && IsStub());
@@ -369,6 +376,9 @@ class V8_EXPORT_PRIVATE CompilationInfo final {
   // refactored to avoid us needing to carry the BytcodeArray around.
   Handle<BytecodeArray> bytecode_array_;
 
+  // Holds the asm_wasm array generated by the asmjs compiler.
+  Handle<FixedArray> asm_wasm_data_;
+
   // The zone from which the compilation pipeline working on this
   // CompilationInfo allocates.
   Zone* zone_;

src/compiler.cc

@@ -358,7 +358,10 @@ void InstallUnoptimizedCode(CompilationInfo* info) {
   shared->ReplaceCode(*info->code());
   if (info->has_bytecode_array()) {
     DCHECK(!shared->HasBytecodeArray());  // Only compiled once.
+    DCHECK(!info->has_asm_wasm_data());
     shared->set_bytecode_array(*info->bytecode_array());
+  } else if (info->has_asm_wasm_data()) {
+    shared->set_asm_wasm_data(*info->asm_wasm_data());
   }
 
   // Install coverage info on the shared function info.
@@ -443,29 +446,20 @@ bool Renumber(ParseInfo* info,
                                 info->collect_type_profile());
 }
 
+bool RunUnoptimizedCompilationJob(CompilationJob* job) {
+  if (job->PrepareJob() != CompilationJob::SUCCEEDED) return false;
+  if (job->ExecuteJob() != CompilationJob::SUCCEEDED) return false;
+  return FinalizeUnoptimizedCompilationJob(job) == CompilationJob::SUCCEEDED;
+}
+
 bool GenerateUnoptimizedCode(CompilationInfo* info) {
   if (UseAsmWasm(info->scope(), info->shared_info(), info->is_debug())) {
-    MaybeHandle<FixedArray> wasm_data;
-    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);
-      return true;
-    }
+    std::unique_ptr<CompilationJob> job(AsmJs::NewCompilationJob(info));
+    if (RunUnoptimizedCompilationJob(job.get())) return true;
+    // asm.js validation failed, fall through to standard unoptimized compile.
   }
-
   std::unique_ptr<CompilationJob> job(GetUnoptimizedCompilationJob(info));
-  if (job->PrepareJob() != CompilationJob::SUCCEEDED) return false;
-  if (job->ExecuteJob() != CompilationJob::SUCCEEDED) return false;
-  if (FinalizeUnoptimizedCompilationJob(job.get()) !=
-      CompilationJob::SUCCEEDED) {
-    return false;
-  }
-  return true;
+  return RunUnoptimizedCompilationJob(job.get());
 }
 
 bool CompileUnoptimizedInnerFunctions(