Re: [reverse/record] adjust_pc_after_break in reverse execution mode?

[Pedro Alves <pedro@codesourcery.com>]

On Tuesday 21 October 2008 00:36:12, teawater wrote:
> I think your mean is check breakpoint in address
> read_pc()+gdbarch_decr_pc_after_break (gdbarch) in record_wait, right?

Taking x86 as an example, when you're doing normal debugging and you
hit a breakpoint (SIGTRAP), the first read_pc GDB does to check where
what breakpoint was hit, will read back `breakpoint_PC + 1' --- GDB takes care
getting rid of that `+ 1' offset in infrun.c:adjust_pc_after_break.  The
idea is for you to do the same as the kernel/hardware would --- still
check for breakpoints at read_pc, but increment PC by 1 before reporting the
breakpoint to GDB's core.  E.g., see the `pc += gdbarch...' line from
the patch I posted previously, something like:

record.c:record_wait ()
{
...
+         /* Check for breakpoint hits in forward execution.  */
+         pc = read_pc ();
+         if (execution_direction == EXEC_FORWARD
+             && regular_breakpoint_inserted_here_p (pc)
+             /* && !single-stepping */)
+           {
+             status->kind = TARGET_WAITKIND_STOPPED;
+             status->value.sig = TARGET_SIGNAL_TRAP;
+             if (software_breakpoint_inserted_here_p (pc))
+               {
+                 pc += gdbarch_decr_pc_after_break (gdbarch);
+                 write_pc (pc);
+               }
+

-- 
Pedro Alves