Add a level of indirection to exception handler addresses.

src/x64/macro-assembler-x64.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 915 matching lines @@
   void AbortIfNotString(Register object);
 
   // Abort execution if argument is not the root value with the given index.
   void AbortIfNotRootValue(Register src,
                            Heap::RootListIndex root_value_index,
                            const char* message);
 
   // ---------------------------------------------------------------------------
   // Exception handling
 
-  // Push a new try handler and link into try handler chain.  The return
-  // address must be pushed before calling this helper.
-  void PushTryHandler(CodeLocation try_location, HandlerType type);
+  // Push a new try handler and link it into try handler chain.
+  void PushTryHandler(CodeLocation try_location,
+                      HandlerType type,
+                      int handler_index);
 
   // Unlink the stack handler on top of the stack from the try handler chain.
   void PopTryHandler();
 
   // Activate the top handler in the try hander chain and pass the
   // thrown value.
   void Throw(Register value);
 
   // Propagate an uncatchable exception out of the current JS stack.
   void ThrowUncatchable(UncatchableExceptionType type, Register value);
@@ skipping 370 matching lines @@
                   Label::Distance distance = Label::kFar);
 
   // Helper for finding the mark bits for an address.  Afterwards, the
   // bitmap register points at the word with the mark bits and the mask
   // the position of the first bit.  Uses rcx as scratch and leaves addr_reg
   // unchanged.
   inline void GetMarkBits(Register addr_reg,
                           Register bitmap_reg,
                           Register mask_reg);
 
+  // Helper for throwing exceptions.  Compute a handler address and jump to
+  // it.  See the implementation for register usage.
+  void JumpToHandlerEntry();
+
   // Compute memory operands for safepoint stack slots.
   Operand SafepointRegisterSlot(Register reg);
   static int SafepointRegisterStackIndex(int reg_code) {
     return kNumSafepointRegisters - kSafepointPushRegisterIndices[reg_code] - 1;
   }
 
   // Needs access to SafepointRegisterStackIndex for optimized frame
   // traversal.
   friend class OptimizedFrame;
 };
@@ skipping 76 matching lines @@
     masm->popfd();                                                        \
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_