[vm/debugger] not pausing exceptions on implicit throw

Ignoring exceptions that coming from implicit throw. For example, try finally block will generate an implicit throw inside finally block to rethrow the exception.

Bug: #37645
Change-Id: I5c4f90ec3c9aa92bb670d4bb9a8edb332f7b32fc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/118911
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Zichang Guo <zichangguo@google.com>

Author: zichangg

runtime/observatory/tests/service/pause_on_unhandled_async_exceptions3_test.dart

@@ -10,16 +10,22 @@ import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'service_test_common.dart';
 
-const LINE_A = 16;
+const LINE_A = 18;
+const LINE_B = 23;
+const LINE_C = 26;
 
 throwException() async {
   throw 'exception'; // LINE_A
 }
 
 testeeMain() async {
   try {
-    await throwException();
-  } finally {}
+    await throwException(); // LINE_B
+  } finally {
+    try {
+      await throwException(); // LINE_C
+    } finally {}
+  }
 }
 
 var tests = <IsolateTest>[
@@ -29,6 +35,26 @@ var tests = <IsolateTest>[
     print("Stopped!");
     var stack = await isolate.getStack();
     expect(stack['frames'][0].function.toString(), contains('throwException'));
+  },
+  resumeIsolate,
+  hasStoppedWithUnhandledException,
+  (Isolate isolate) async {
+    var stack = await isolate.getStack();
+    print(stack['frames'][0]);
+    // await in testeeMain
+    expect(await stack['frames'][0].location.toUserString(),
+        contains('.dart:${LINE_B}'));
+  },
+  resumeIsolate,
+  hasStoppedWithUnhandledException,
+  stoppedAtLine(LINE_A),
+  resumeIsolate,
+  hasStoppedWithUnhandledException,
+  (Isolate isolate) async {
+    var stack = await isolate.getStack();
+    print(stack['frames'][0]);
+    expect(await stack['frames'][0].location.toUserString(),
+        contains('.dart:${LINE_C}'));
   }
 ];
 

runtime/vm/debugger.cc

@@ -2780,6 +2780,11 @@ bool Debugger::ShouldPauseOnException(DebuggerStackTrace* stack_trace,
     return true;
   }
   ASSERT(exc_pause_info_ == kPauseOnUnhandledExceptions);
+  // Exceptions coming from invalid token positions should be skipped
+  ActivationFrame* top_frame = stack_trace->FrameAt(0);
+  if (!top_frame->TokenPos().IsReal() && top_frame->TryIndex() != -1) {
+    return false;
+  }
   ActivationFrame* handler_frame = stack_trace->GetHandlerFrame(exception);
   if (handler_frame == NULL) {
     // Did not find an exception handler that catches this exception.