[Bug breakpoints/16703] New: The program breaks at the next instruction when issuing a memory breakpoint on AVR8.

["pierre.langlois at embecosm dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=16703

            Bug ID: 16703
           Summary: The program breaks at the next instruction when
                    issuing a memory breakpoint on AVR8.
           Product: gdb
           Version: 7.7
            Status: NEW
          Severity: normal
          Priority: P2
         Component: breakpoints
          Assignee: unassigned at sourceware dot org
          Reporter: pierre.langlois at embecosm dot com

Created attachment 7469
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7469&action=edit
Simple program ran on the ATxmega256a3b chip

When setting breakpoints on AVR, using gdb against the simulator models, using
the ATxmega256a3u, the program counter needs to be decremented after a
breakpoint is hit. This only happens with memory breakpoints.

------------------------------------------------------------------------------

GNU gdb (AVR 8-bit toolchain (built 20140310)) 7.7.50.20140313-cvs
Copyright (C) 2014 Free Software Foundation, Inc.
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(gdb) set redebug remote 1
(gdb) target remote :51000
Remote debugging using :51000
0x0000020e in ?? ()
(gdb) file atxmega-test.elf 
A program is being debugged already.
Are you sure you want to change the file? (y or n) Reading symbols from
atxmega-test.elf...done.
(gdb) load
Loading section .text, size 0x22e lma 0x0
Start address 0x0, load size 558
Transfer rate: 544 KB/sec, 186 bytes/write.
(gdb) monitor reset
(gdb) break main
Breakpoint 1 at 0x204: file main.c, line 7.
(gdb) continue
Continuing.

Program received signal SIGTRAP, Trace/breakpoint trap.
0x00000206 in main () at main.c:7
7      PORTR.DIRSET = 3;
(gdb) break *(@code void *) 0x106
Breakpoint 2 at 0x20c: file main.c, line 8.
(gdb) continue
Continuing.

Program received signal SIGTRAP, Trace/breakpoint trap.
0x0000020e in main () at main.c:8
8      PORTR.OUTSET = 1;
(gdb) p/x $pc
$1 = 0x20e
(gdb) info breakpoints 
Num     Type           Disp Enb Address    What
1       breakpoint     keep y   0x00000204 in main at main.c:7
2       breakpoint     keep y   0x0000020c in main at main.c:8
(gdb) q
A debugging session is active.

    Inferior 1 [Remote target] will be killed.

Quit anyway? (y or n)

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