Merge GDB 7.5.1

gdb/frame-unwind.h

 /* Definitions for a frame unwinder, for GDB, the GNU debugger.
 
    Copyright (C) 2003-2004, 2007-2012 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
@@ skipping 26 matching lines @@
 
    THIS frame's register values can be obtained by unwinding NEXT
    frame's registers (a recursive operation).
 
    THIS frame's prologue cache can be used to cache information such
    as where this frame's prologue stores the previous frame's
    registers.  */
 
 /* Given THIS frame, take a whiff of its registers (namely
    the PC and attributes) and if SELF is the applicable unwinder,
-   return non-zero.  Possibly also initialize THIS_PROLOGUE_CACHE.  */
+   return non-zero.  Possibly also initialize THIS_PROLOGUE_CACHE; but
+   only if returning 1.  Initializing THIS_PROLOGUE_CACHE in other
+   cases (0 return, or exception) is invalid.  */
 
 typedef int (frame_sniffer_ftype) (const struct frame_unwind *self,
                                    struct frame_info *this_frame,
                                    void **this_prologue_cache);
 
 typedef enum unwind_stop_reason (frame_unwind_stop_reason_ftype)
   (struct frame_info *this_frame, void **this_prologue_cache);
 
 /* A default frame sniffer which always accepts the frame.  Used by
    fallback prologue unwinders.  */
@@ skipping 153 matching lines @@
                                       gdb_byte *buf);
 
 /* Return a value which indicates that FRAME's saved version of REGNUM
    has a known constant (computed) value of ADDR.  Convert the
    CORE_ADDR to a target address if necessary.  */
 
 struct value *frame_unwind_got_address (struct frame_info *frame, int regnum,
                                         CORE_ADDR addr);
 
 #endif