Reland "[wasm] Remove finisher task"

This is a reland of ac2fb66b.
Crashes were fixed in https://crrev.com/c/1429862.

Original change's description:
> [wasm] Remove finisher task
>
> This removes the finisher task and instead finishes compilation units
> from the background.
> It also changes ownership of the AsyncCompileJob to be shared among all
> tasks that still operate on it. The AsyncCompileJob dies when the last
> reference dies.
>
> R=ahaas@chromium.org
> CC=​​mstarzinger@chromium.org
>
> Bug: v8:7921, v8:8423
> Change-Id: Id09378327dfc146459ef41bc97176a8716756ae4
> Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel
> Reviewed-on: https://chromium-review.googlesource.com/c/1335553
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#58630}

Bug: v8:7921, v8:8423
Change-Id: I3dcee4e8e56d2a524d302af91b5cb4a7a9ceb8ce
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel
Reviewed-on: https://chromium-review.googlesource.com/c/1400781
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59302}

src/wasm/compilation-environment.h

@@ -102,7 +102,7 @@ class CompilationState {
 
   ~CompilationState();
 
-  void CancelAndWait();
+  void AbortCompilation();
 
   void SetError(uint32_t func_index, const WasmError& error);
 

src/wasm/module-compiler.h

@@ -99,6 +99,7 @@ class AsyncCompileJob {
   // function should finish the asynchronous compilation, see the comment on
   // {outstanding_finishers_}.
   V8_WARN_UNUSED_RESULT bool DecrementAndCheckFinisherCount() {
+    DCHECK_LT(0, outstanding_finishers_.load());
     return outstanding_finishers_.fetch_sub(1) == 1;
   }
 

src/wasm/wasm-code-manager.cc

@@ -894,7 +894,7 @@ NativeModule::~NativeModule() {
   TRACE_HEAP("Deleting native module: %p\n", reinterpret_cast<void*>(this));
   // Cancel all background compilation before resetting any field of the
   // NativeModule or freeing anything.
-  compilation_state_->CancelAndWait();
+  compilation_state_->AbortCompilation();
   engine_->FreeNativeModule(this);
 }
 

src/wasm/wasm-engine.cc

@@ -90,7 +90,7 @@ WasmEngine::~WasmEngine() {
   // Synchronize on all background compile tasks.
   background_compile_task_manager_.CancelAndWait();
   // All AsyncCompileJobs have been canceled.
-  DCHECK(jobs_.empty());
+  DCHECK(async_compile_jobs_.empty());
   // All Isolates have been deregistered.
   DCHECK(isolates_.empty());
   // All NativeModules did die.
@@ -361,26 +361,26 @@ AsyncCompileJob* WasmEngine::CreateAsyncCompileJob(
   AsyncCompileJob* job =
       new AsyncCompileJob(isolate, enabled, std::move(bytes_copy), length,
                           context, std::move(resolver));
-  // Pass ownership to the unique_ptr in {jobs_}.
+  // Pass ownership to the unique_ptr in {async_compile_jobs_}.
   base::MutexGuard guard(&mutex_);
-  jobs_[job] = std::unique_ptr<AsyncCompileJob>(job);
+  async_compile_jobs_[job] = std::unique_ptr<AsyncCompileJob>(job);
   return job;
 }
 
 std::unique_ptr<AsyncCompileJob> WasmEngine::RemoveCompileJob(
     AsyncCompileJob* job) {
   base::MutexGuard guard(&mutex_);
-  auto item = jobs_.find(job);
-  DCHECK(item != jobs_.end());
+  auto item = async_compile_jobs_.find(job);
+  DCHECK(item != async_compile_jobs_.end());
   std::unique_ptr<AsyncCompileJob> result = std::move(item->second);
-  jobs_.erase(item);
+  async_compile_jobs_.erase(item);
   return result;
 }
 
 bool WasmEngine::HasRunningCompileJob(Isolate* isolate) {
   base::MutexGuard guard(&mutex_);
   DCHECK_EQ(1, isolates_.count(isolate));
-  for (auto& entry : jobs_) {
+  for (auto& entry : async_compile_jobs_) {
     if (entry.first->isolate() == isolate) return true;
   }
   return false;
@@ -393,13 +393,14 @@ void WasmEngine::DeleteCompileJobsOnIsolate(Isolate* isolate) {
   {
     base::MutexGuard guard(&mutex_);
     DCHECK_EQ(1, isolates_.count(isolate));
-    for (auto it = jobs_.begin(); it != jobs_.end();) {
+    for (auto it = async_compile_jobs_.begin();
+         it != async_compile_jobs_.end();) {
       if (it->first->isolate() != isolate) {
         ++it;
         continue;
       }
       jobs_to_delete.push_back(std::move(it->second));
-      it = jobs_.erase(it);
+      it = async_compile_jobs_.erase(it);
     }
   }
 }

src/wasm/wasm-engine.h

@@ -205,7 +205,8 @@ class V8_EXPORT_PRIVATE WasmEngine {
 
   // We use an AsyncCompileJob as the key for itself so that we can delete the
   // job from the map when it is finished.
-  std::unordered_map<AsyncCompileJob*, std::unique_ptr<AsyncCompileJob>> jobs_;
+  std::unordered_map<AsyncCompileJob*, std::unique_ptr<AsyncCompileJob>>
+      async_compile_jobs_;
 
   std::unique_ptr<CompilationStatistics> compilation_stats_;
   std::unique_ptr<CodeTracer> code_tracer_;