[wasm] Remove the wasm-stream-compilation flag

In addition to a git grep I ran the
virtual/enable_wasm_streaming/http/tests/wasm_streaming/wasm_response_apis.html
layout test locally to confirm that the flag is not used in Chrome.

R=titzer@chromium.org

Cq-Include-Trybots: luci.chromium.try:linux_chromium_rel_ng
Change-Id: I00d013b85b585d26e50aacaeb82fb0b1ce1ff56c
Reviewed-on: https://chromium-review.googlesource.com/1049965Reviewed-by: Ben Titzer <titzer@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53072}

include/v8.h

@@ -4272,8 +4272,6 @@ class V8_EXPORT WasmModuleObjectBuilderStreaming final {
   ~WasmModuleObjectBuilderStreaming();
 
  private:
-  typedef std::pair<std::unique_ptr<const uint8_t[]>, size_t> Buffer;
-
   WasmModuleObjectBuilderStreaming(const WasmModuleObjectBuilderStreaming&) =
       delete;
   WasmModuleObjectBuilderStreaming(WasmModuleObjectBuilderStreaming&&) =
@@ -4296,8 +4294,6 @@ class V8_EXPORT WasmModuleObjectBuilderStreaming final {
 #else
   Persistent<Promise> promise_;
 #endif
-  std::vector<Buffer> received_buffers_;
-  size_t total_size_ = 0;
   std::shared_ptr<internal::wasm::StreamingDecoder> streaming_decoder_;
 };
 

src/api.cc

@@ -7514,15 +7514,13 @@ WasmModuleObjectBuilderStreaming::WasmModuleObjectBuilderStreaming(
   Local<Promise::Resolver> resolver = maybe_resolver.ToLocalChecked();
   promise_.Reset(isolate, resolver->GetPromise());
 
-  if (i::FLAG_wasm_stream_compilation) {
-    i::Handle<i::JSPromise> promise = Utils::OpenHandle(*GetPromise());
-    i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
-    streaming_decoder_ =
-        i_isolate->wasm_engine()
-            ->compilation_manager()
-            ->StartStreamingCompilation(i_isolate, handle(i_isolate->context()),
-                                        promise);
-  }
+  i::Handle<i::JSPromise> promise = Utils::OpenHandle(*GetPromise());
+  i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  streaming_decoder_ =
+      i_isolate->wasm_engine()
+          ->compilation_manager()
+          ->StartStreamingCompilation(i_isolate, handle(i_isolate->context()),
+                                      promise);
 }
 
 Local<Promise> WasmModuleObjectBuilderStreaming::GetPromise() {
@@ -7531,38 +7529,11 @@ Local<Promise> WasmModuleObjectBuilderStreaming::GetPromise() {
 
 void WasmModuleObjectBuilderStreaming::OnBytesReceived(const uint8_t* bytes,
                                                        size_t size) {
-  if (i::FLAG_wasm_stream_compilation) {
-    streaming_decoder_->OnBytesReceived(i::Vector<const uint8_t>(bytes, size));
-    return;
-  }
-  std::unique_ptr<uint8_t[]> cloned_bytes(new uint8_t[size]);
-  memcpy(cloned_bytes.get(), bytes, size);
-  received_buffers_.push_back(
-      Buffer(std::unique_ptr<const uint8_t[]>(
-                 const_cast<const uint8_t*>(cloned_bytes.release())),
-             size));
-  total_size_ += size;
+  streaming_decoder_->OnBytesReceived(i::Vector<const uint8_t>(bytes, size));
 }
 
 void WasmModuleObjectBuilderStreaming::Finish() {
-  if (i::FLAG_wasm_stream_compilation) {
-    streaming_decoder_->Finish();
-    return;
-  }
-  std::unique_ptr<uint8_t[]> wire_bytes(new uint8_t[total_size_]);
-  uint8_t* insert_at = wire_bytes.get();
-
-  for (size_t i = 0; i < received_buffers_.size(); ++i) {
-    const Buffer& buff = received_buffers_[i];
-    memcpy(insert_at, buff.first.get(), buff.second);
-    insert_at += buff.second;
-  }
-  // AsyncCompile makes its own copy of the wire bytes. This inefficiency
-  // will be resolved when we move to true streaming compilation.
-  auto i_isolate = reinterpret_cast<i::Isolate*>(isolate_);
-  i_isolate->wasm_engine()->AsyncCompile(
-      i_isolate, Utils::OpenHandle(*promise_.Get(isolate_)),
-      {wire_bytes.get(), wire_bytes.get() + total_size_}, false);
+  streaming_decoder_->Finish();
 }
 
 void WasmModuleObjectBuilderStreaming::Abort(MaybeLocal<Value> exception) {
@@ -7570,7 +7541,7 @@ void WasmModuleObjectBuilderStreaming::Abort(MaybeLocal<Value> exception) {
   // The promise has already been resolved, e.g. because of a compilation
   // error.
   if (promise->State() != v8::Promise::kPending) return;
-  if (i::FLAG_wasm_stream_compilation) streaming_decoder_->Abort();
+  streaming_decoder_->Abort();
 
   // If no exception value is provided, we do not reject the promise. This can
   // happen when streaming compilation gets aborted when no script execution is

src/flag-definitions.h

@@ -521,12 +521,8 @@ DEFINE_BOOL(wasm_trace_serialization, false,
             "trace serialization/deserialization")
 DEFINE_BOOL(wasm_async_compilation, true,
             "enable actual asynchronous compilation for WebAssembly.compile")
-DEFINE_BOOL(wasm_stream_compilation, true,
-            "enable streaming compilation for WebAssembly")
-DEFINE_IMPLICATION(wasm_stream_compilation, wasm_async_compilation)
 DEFINE_BOOL(wasm_test_streaming, false,
             "use streaming compilation instead of async compilation for tests")
-DEFINE_IMPLICATION(wasm_test_streaming, wasm_stream_compilation)
 // Parallel compilation confuses turbo_stats, force single threaded.
 DEFINE_VALUE_IMPLICATION(turbo_stats, wasm_num_compilation_tasks, 0)
 DEFINE_UINT(wasm_max_mem_pages, v8::internal::wasm::kV8MaxWasmMemoryPages,