Revert "[wasm] Move code generation fully to background task."

This reverts commit 231b3e15.

Reason for revert: Flakes in inspector/debugger/wasm-stack

Original change's description:
> [wasm] Move code generation fully to background task.
> 
> This moves the entire code generation phase (including code emission
> into the native module) into the background task. The code manager is
> fully thread safe by now and there are no Isolate-bound steps anymore.
> 
> R=​clemensh@chromium.org
> BUG=v8:7921
> 
> Change-Id: Ie3e8565e126bfdb58bf472291a1f9fbebe7b5431
> Reviewed-on: https://chromium-review.googlesource.com/1128743
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54324}

TBR=mstarzinger@chromium.org,clemensh@chromium.org

Change-Id: Ice5d80425cebd3921d9683d06f70d5173f663e42
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7921
Reviewed-on: https://chromium-review.googlesource.com/1129059Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54326}

src/compiler/pipeline.cc

@@ -1053,10 +1053,18 @@ PipelineWasmCompilationJob::ExecuteJobImpl() {
   pipeline_.ComputeScheduledGraph();
   if (!pipeline_.SelectInstructions(&linkage_)) return FAILED;
   pipeline_.AssembleCode(&linkage_);
+  return SUCCEEDED;
+}
 
+size_t PipelineWasmCompilationJob::AllocatedMemory() const {
+  return pipeline_.data_->zone_stats()->GetCurrentAllocatedBytes();
+}
+
+PipelineWasmCompilationJob::Status PipelineWasmCompilationJob::FinalizeJobImpl(
+    Isolate* isolate) {
   CodeGenerator* code_generator = pipeline_.data_->code_generator();
   CodeDesc code_desc;
-  code_generator->tasm()->GetCode(nullptr, &code_desc);
+  code_generator->tasm()->GetCode(isolate, &code_desc);
 
   wasm::WasmCode* code = native_module_->AddCode(
       data_.wasm_function_index(), code_desc,
@@ -1066,13 +1074,15 @@ PipelineWasmCompilationJob::ExecuteJobImpl() {
       data_.wasm_compilation_data()->GetProtectedInstructions(),
       code_generator->GetSourcePositionTable(), wasm::WasmCode::kTurbofan);
 
+  if (!code) return FAILED;
+
   if (data_.info()->trace_turbo_json_enabled()) {
     TurboJsonFile json_of(data_.info(), std::ios_base::app);
     json_of << "{\"name\":\"disassembly\",\"type\":\"disassembly\",\"data\":\"";
 #ifdef ENABLE_DISASSEMBLER
     std::stringstream disassembler_stream;
     Disassembler::Decode(
-        nullptr, &disassembler_stream, code->instructions().start(),
+        isolate, &disassembler_stream, code->instructions().start(),
         code->instructions().start() + code->safepoint_table_offset(),
         CodeReference(code));
     for (auto const c : disassembler_stream.str()) {
@@ -1088,16 +1098,6 @@ PipelineWasmCompilationJob::ExecuteJobImpl() {
   return SUCCEEDED;
 }
 
-size_t PipelineWasmCompilationJob::AllocatedMemory() const {
-  return pipeline_.data_->zone_stats()->GetCurrentAllocatedBytes();
-}
-
-PipelineWasmCompilationJob::Status PipelineWasmCompilationJob::FinalizeJobImpl(
-    Isolate* isolate) {
-  UNREACHABLE();  // Finalize should always be skipped for WasmCompilationJob.
-  return SUCCEEDED;
-}
-
 template <typename Phase>
 void PipelineImpl::Run() {
   PipelineRunScope scope(this->data_, Phase::phase_name());

src/compiler/wasm-compiler.cc

@@ -5258,6 +5258,22 @@ wasm::WasmCode* TurbofanWasmCompilationUnit::FinishCompilation(
 
     return nullptr;
   }
+  base::ElapsedTimer codegen_timer;
+  if (FLAG_trace_wasm_decode_time) {
+    codegen_timer.Start();
+  }
+
+  if (job_->FinalizeJob(wasm_unit_->isolate_) != CompilationJob::SUCCEEDED) {
+    return nullptr;
+  }
+
+  if (FLAG_trace_wasm_decode_time) {
+    double codegen_ms = codegen_timer.Elapsed().InMillisecondsF();
+    PrintF("wasm-code-generation ok: %u bytes, %0.3f ms code generation\n",
+           static_cast<unsigned>(wasm_unit_->func_body_.end -
+                                 wasm_unit_->func_body_.start),
+           codegen_ms);
+  }
 
   return job_->compilation_info()->wasm_code();
 }

src/wasm/wasm-code-manager.cc

@@ -725,7 +725,6 @@ void NativeModule::DisableTrapHandler() {
 
 NativeModule::~NativeModule() {
   TRACE_HEAP("Deleting native module: %p\n", reinterpret_cast<void*>(this));
-  compilation_state_.reset();  // Cancels tasks, needs to be done first.
   wasm_code_manager_->FreeNativeModule(this);
 }
 

src/wasm/wasm-code-manager.h

@@ -387,19 +387,15 @@ class V8_EXPORT_PRIVATE NativeModule final {
   // Jump table used to easily redirect wasm function calls.
   WasmCode* jump_table_ = nullptr;
 
-  // The compilation state keeps track of compilation tasks for this module.
-  // Note that its destructor blocks until all tasks are finished/aborted and
-  // hence needs to be destructed first when this native module dies.
   std::unique_ptr<CompilationState, CompilationStateDeleter> compilation_state_;
 
-  // This mutex protects concurrent calls to {AddCode} and {AddCodeCopy}.
-  mutable base::Mutex allocation_mutex_;
-
   DisjointAllocationPool free_code_space_;
   DisjointAllocationPool allocated_code_space_;
   std::list<VirtualMemory> owned_code_space_;
 
   WasmCodeManager* wasm_code_manager_;
+  // This mutex protects concurrent calls to {AddCode} and {AddCodeCopy}.
+  mutable base::Mutex allocation_mutex_;
   size_t committed_code_space_ = 0;
   int modification_scope_depth_ = 0;
   bool can_request_more_memory_;