+ int first = 1;
+
+ /* There are at least 3 possibilities to share an unwind info entry:
+ 1. Two different runtime_function entries (in .pdata) can point to the
+ same unwind info entry. There is no such indication while unwinding,
+ so we don't really care about that case. We suppose this scheme is
+ used to save memory when the unwind entries are exactly the same.
+ 2. Chained unwind_info entries, with no unwind codes (no prologue).
+ There is a major difference with the previous case: the pc range for
+ the function is different (in case 1, the pc range comes from the
+ runtime_function entry; in case 2, the pc range for the chained entry
+ comes from the first unwind entry). Case 1 cannot be used instead as
+ the pc is not in the prologue. This case is officially documented.
+ (There might be unwind code in the first unwind entry to handle
+ additional unwinding). GCC (at least until gcc 5.0) doesn't chain
+ entries.
+ 3. Undocumented unwind info redirection. Hard to know the exact purpose,
+ so it is considered as a memory optimization of case 2.
+ */