[wasm][eh] Add metrics for total EH event counts

R=ahaas@chromium.org

Bug: v8:8091
Change-Id: I3d1053b3a11bf81ed2e58098f8429683d4e753ed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2690597Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72740}

src/logging/counters-definitions.h

@@ -85,6 +85,12 @@ namespace internal {
   HR(wasm_modules_per_engine, V8.WasmModulesPerEngine, 1, 1024, 30)            \
   /* bailout reason if Liftoff failed, or {kSuccess} (per function) */         \
   HR(liftoff_bailout_reasons, V8.LiftoffBailoutReasons, 0, 20, 21)             \
+  /* number of thrown exceptions per isolate */                                \
+  HR(wasm_throw_count, V8.WasmThrowCount, 0, 100000, 30)                       \
+  /* number of rethrown exceptions per isolate */                              \
+  HR(wasm_rethrow_count, V8.WasmReThrowCount, 0, 100000, 30)                   \
+  /* number of caught exceptions per isolate */                                \
+  HR(wasm_catch_count, V8.WasmCatchCount, 0, 100000, 30)                       \
   /* Ticks observed in a single Turbofan compilation, in 1K */                 \
   HR(turbofan_ticks, V8.TurboFan1KTicks, 0, 100000, 200)                       \
   /* Backtracks observed in a single regexp interpreter execution */           \

src/wasm/wasm-engine.cc

@@ -394,6 +394,11 @@ struct WasmEngine::IsolateInfo {
   base::ElapsedTimer throw_timer;
   base::ElapsedTimer rethrow_timer;
   base::ElapsedTimer catch_timer;
+
+  // Total number of exception events in this isolate.
+  int throw_count = 0;
+  int rethrow_count = 0;
+  int catch_count = 0;
 };
 
 struct WasmEngine::NativeModuleInfo {
@@ -1007,6 +1012,9 @@ void WasmEngine::RemoveIsolate(Isolate* isolate) {
   for (auto& log_entry : info->code_to_log) {
     WasmCode::DecrementRefCount(VectorOf(log_entry.second.code));
   }
+  isolate->counters()->wasm_throw_count()->AddSample(info->throw_count);
+  isolate->counters()->wasm_rethrow_count()->AddSample(info->rethrow_count);
+  isolate->counters()->wasm_catch_count()->AddSample(info->catch_count);
 }
 
 void WasmEngine::LogCode(Vector<WasmCode*> code_vec) {
@@ -1389,18 +1397,30 @@ void SampleExceptionEvent(base::ElapsedTimer* timer, TimedHistogram* counter) {
 
 void WasmEngine::SampleThrowEvent(Isolate* isolate) {
   base::MutexGuard guard(&mutex_);
+  int& throw_count = isolates_[isolate]->throw_count;
+  // To avoid an int overflow, clip the count to the histogram's max value.
+  throw_count =
+      std::min(throw_count + 1, isolate->counters()->wasm_throw_count()->max());
   SampleExceptionEvent(&isolates_[isolate]->throw_timer,
                        isolate->counters()->wasm_time_between_throws());
 }
 
 void WasmEngine::SampleRethrowEvent(Isolate* isolate) {
   base::MutexGuard guard(&mutex_);
+  int& rethrow_count = isolates_[isolate]->rethrow_count;
+  // To avoid an int overflow, clip the count to the histogram's max value.
+  rethrow_count = std::min(rethrow_count + 1,
+                           isolate->counters()->wasm_rethrow_count()->max());
   SampleExceptionEvent(&isolates_[isolate]->rethrow_timer,
                        isolate->counters()->wasm_time_between_rethrows());
 }
 
 void WasmEngine::SampleCatchEvent(Isolate* isolate) {
   base::MutexGuard guard(&mutex_);
+  int& catch_count = isolates_[isolate]->catch_count;
+  // To avoid an int overflow, clip the count to the histogram's max value.
+  catch_count =
+      std::min(catch_count + 1, isolate->counters()->wasm_catch_count()->max());
   SampleExceptionEvent(&isolates_[isolate]->catch_timer,
                        isolate->counters()->wasm_time_between_catch());
 }