[debug] use catch prediction flag for promise rejections.

src/objects.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/assert-scope.h"
@@ skipping 4842 matching lines @@
 //    handler. Layout looks as follows:
 //      [ range-start , range-end , handler-offset , handler-data ]
 // 2) Based on return addresses: Used for turbofanned code. Contains one entry
 //    per call-site that could throw an exception. Layout looks as follows:
 //      [ return-address-offset , handler-offset ]
 class HandlerTable : public FixedArray {
  public:
   // Conservative prediction whether a given handler will locally catch an
   // exception or cause a re-throw to outside the code boundary. Since this is
   // undecidable it is merely an approximation (e.g. useful for debugger).
-  enum CatchPrediction { UNCAUGHT, CAUGHT };
+  enum CatchPrediction {
+    UNCAUGHT,  // the handler will (likely) rethrow the exception.
+    CAUGHT,    // the exception will be caught by the handler.
+    PROMISE    // the exception will be caught and cause a promise rejection.
+  };
 
   // Getters for handler table based on ranges.
   inline int GetRangeStart(int index) const;
   inline int GetRangeEnd(int index) const;
   inline int GetRangeHandler(int index) const;
   inline int GetRangeData(int index) const;
 
   // Setters for handler table based on ranges.
   inline void SetRangeStart(int index, int value);
   inline void SetRangeEnd(int index, int value);
@@ skipping 34 matching lines @@
   static const int kRangeHandlerIndex = 2;
   static const int kRangeDataIndex = 3;
   static const int kRangeEntrySize = 4;
 
   // Layout description for handler table based on return addresses.
   static const int kReturnOffsetIndex = 0;
   static const int kReturnHandlerIndex = 1;
   static const int kReturnEntrySize = 2;
 
   // Encoding of the {handler} field.
-  class HandlerPredictionField : public BitField<CatchPrediction, 0, 1> {};
-  class HandlerOffsetField : public BitField<int, 1, 30> {};
+  class HandlerPredictionField : public BitField<CatchPrediction, 0, 2> {};
+  class HandlerOffsetField : public BitField<int, 2, 30> {};
 };
 
 
 // Code describes objects with on-the-fly generated machine code.
 class Code: public HeapObject {
  public:
   // Opaque data type for encapsulating code flags like kind, inline
   // cache state, and arguments count.
   typedef uint32_t Flags;
 
@@ skipping 6059 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_