[wasm] Improve wasm code logging

This fixes a few thing regarding code logging for profiling:

1) Append the execution tier, otherwise we get two function of the same
   name.
2) Replace "wasm-function[%d]" by "<wasm-unnamed>", since the index is
   appended later anyway.
3) Avoid unneeded JS heap and C++ heap allocations during logging.

R=jkummerow@chromium.org

Bug: chromium:1029470
Change-Id: Ie7af41f21e4595f8d8c574e4ad18273f89f1cb6e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1943162
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65285}

src/logging/log.cc

@@ -245,6 +245,8 @@ void CodeEventLogger::CodeCreateEvent(LogEventsAndTags tag,
   } else {
     name_buffer_->AppendInt(code->index());
   }
+  name_buffer_->AppendByte('-');
+  name_buffer_->AppendBytes(ExecutionTierToString(code->tier()));
   LogRecordedBuffer(code, name_buffer_->get(), name_buffer_->size());
 }
 

src/wasm/wasm-code-manager.cc

@@ -194,28 +194,27 @@ void WasmCode::LogCode(Isolate* isolate) const {
         std::make_unique<WasmModuleSourceMap>(v8_isolate, source_map_str));
   }
 
-  if (!name_vec.empty()) {
+  std::unique_ptr<char[]> name_buffer;
+  Vector<const char> name;
+  if (name_vec.empty()) {
+    name = CStrVector("<wasm-unnamed>");
+  } else {
     HandleScope scope(isolate);
     MaybeHandle<String> maybe_name = isolate->factory()->NewStringFromUtf8(
         Vector<const char>::cast(name_vec));
-    Handle<String> name;
-    if (!maybe_name.ToHandle(&name)) {
-      name = isolate->factory()->NewStringFromAsciiChecked("<name too long>");
+    Handle<String> name_string;
+    if (maybe_name.ToHandle(&name_string)) {
+      int name_len = 0;
+      name_buffer = name_string->ToCString(
+          AllowNullsFlag::DISALLOW_NULLS,
+          RobustnessFlag::ROBUST_STRING_TRAVERSAL, &name_len);
+      name = VectorOf(name_buffer.get(), name_len);
+    } else {
+      name = CStrVector("<name too long>");
     }
-    int name_length;
-    auto cname =
-        name->ToCString(AllowNullsFlag::DISALLOW_NULLS,
-                        RobustnessFlag::ROBUST_STRING_TRAVERSAL, &name_length);
-    PROFILE(isolate,
-            CodeCreateEvent(CodeEventListener::FUNCTION_TAG, this,
-                            {cname.get(), static_cast<size_t>(name_length)}));
-  } else {
-    EmbeddedVector<char, 32> generated_name;
-    int length = SNPrintF(generated_name, "wasm-function[%d]", index());
-    generated_name.Truncate(length);
-    PROFILE(isolate, CodeCreateEvent(CodeEventListener::FUNCTION_TAG, this,
-                                     generated_name));
   }
+  PROFILE(isolate,
+          CodeCreateEvent(CodeEventListener::FUNCTION_TAG, this, name));
 
   if (!source_positions().empty()) {
     LOG_CODE_EVENT(isolate, CodeLinePosInfoRecordEvent(instruction_start(),