Add a level of indirection to exception handler addresses.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 3a655efc8b7d06c928fb47e51082b2d99b72eb8e..e1823bf562cd54ca05d5b6e4e5d9afdef4349239 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -933,9 +933,10 @@ class MacroAssembler: public Assembler {
   // ---------------------------------------------------------------------------
   // 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();
@@ -1326,6 +1327,10 @@ class MacroAssembler: public Assembler {
                           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) {