infrun.c

早期freebsd实现

#endif
	    break;
	  }
      
      if (step_resume_break_address)
	/* Having a step-resume breakpoint overrides anything
	   else having to do with stepping commands until
	   that breakpoint is reached.  */
	;
      /* If stepping through a line, keep going if still within it.  */
      else if (!random_signal
	       && step_range_end
	       && stop_pc >= step_range_start
	       && stop_pc < step_range_end
	       /* The step range might include the start of the
		  function, so if we are at the start of the
		  step range and either the stack or frame pointers
		  just changed, we've stepped outside */
	       && !(stop_pc == step_range_start
		    && stop_frame_address
		    && (stop_sp INNER_THAN prev_sp
			|| stop_frame_address != step_frame_address)))
	{
	  ;
	}
      
      /* We stepped out of the stepping range.  See if that was due
	 to a subroutine call that we should proceed to the end of.  */
      else if (!random_signal && step_range_end)
	{
	  if (stop_func_start)
	    {
	      prologue_pc = stop_func_start;
	      SKIP_PROLOGUE (prologue_pc);
	    }

	  /* Did we just take a signal?  */
	  if (IN_SIGTRAMP (stop_pc, stop_func_name)
	      && !IN_SIGTRAMP (prev_pc, prev_func_name))
	    {
	      /* This code is needed at least in the following case:
		 The user types "next" and then a signal arrives (before
		 the "next" is done).  */
	      /* We've just taken a signal; go until we are back to
		 the point where we took it and one more.  */
	      step_resume_break_address = prev_pc;
	      step_resume_break_duplicate =
		breakpoint_here_p (step_resume_break_address);
	      if (breakpoints_inserted)
		insert_step_breakpoint ();
	      /* Make sure that the stepping range gets us past
		 that instruction.  */
	      if (step_range_end == 1)
		step_range_end = (step_range_start = prev_pc) + 1;
	      remove_breakpoints_on_following_step = 1;
	      goto save_pc;
	    }

	  /* ==> See comments at top of file on this algorithm.  <==*/
	  
	  if ((stop_pc == stop_func_start
	       || IN_SOLIB_TRAMPOLINE (stop_pc, stop_func_name))
	      && (stop_func_start != prev_func_start
		  || prologue_pc != stop_func_start
		  || stop_sp != prev_sp))
	    {
	      /* It's a subroutine call.
		 (0)  If we are not stepping over any calls ("stepi"), we
		      just stop.
		 (1)  If we're doing a "next", we want to continue through
		      the call ("step over the call").
		 (2)  If we are in a function-call trampoline (a stub between
		      the calling routine and the real function), locate
		      the real function and change stop_func_start.
		 (3)  If we're doing a "step", and there are no debug symbols
		      at the target of the call, we want to continue through
		      it ("step over the call").
		 (4)  Otherwise, we want to stop soon, after the function
		      prologue ("step into the call"). */

	      if (step_over_calls == 0)
		{
		  /* I presume that step_over_calls is only 0 when we're
		     supposed to be stepping at the assembly language level. */
		  stop_step = 1;
		  break;
		}

	      if (step_over_calls > 0)
		goto step_over_function;

	      tmp = SKIP_TRAMPOLINE_CODE (stop_pc);
	      if (tmp != 0)
		stop_func_start = tmp;

	      if (find_pc_function (stop_func_start) != 0)
	        goto step_into_function;

step_over_function:
	      /* A subroutine call has happened.  */
	      /* Set a special breakpoint after the return */
	      step_resume_break_address =
		ADDR_BITS_REMOVE
		  (SAVED_PC_AFTER_CALL (get_current_frame ()));
	      step_resume_break_duplicate
		= breakpoint_here_p (step_resume_break_address);
	      if (breakpoints_inserted)
		insert_step_breakpoint ();
	      goto save_pc;

step_into_function:
	      /* Subroutine call with source code we should not step over.
		 Do step to the first line of code in it.  */
	      SKIP_PROLOGUE (stop_func_start);
	      sal = find_pc_line (stop_func_start, 0);
	      /* Use the step_resume_break to step until
		 the end of the prologue, even if that involves jumps
		 (as it seems to on the vax under 4.2).  */
	      /* If the prologue ends in the middle of a source line,
		 continue to the end of that source line.
		 Otherwise, just go to end of prologue.  */
#ifdef PROLOGUE_FIRSTLINE_OVERLAP
	      /* no, don't either.  It skips any code that's
		 legitimately on the first line.  */
#else
	      if (sal.end && sal.pc != stop_func_start)
		stop_func_start = sal.end;
#endif

	      if (stop_func_start == stop_pc)
		{
		  /* We are already there: stop now.  */
		  stop_step = 1;
		  break;
		}	
	      else
		/* Put the step-breakpoint there and go until there. */
		{
		  step_resume_break_address = stop_func_start;
		  
		  step_resume_break_duplicate
		    = breakpoint_here_p (step_resume_break_address);
		  if (breakpoints_inserted)
		    insert_step_breakpoint ();
		  /* Do not specify what the fp should be when we stop
		     since on some machines the prologue
		     is where the new fp value is established.  */
		  step_frame_address = 0;
		  /* And make sure stepping stops right away then.  */
		  step_range_end = step_range_start;
		}
	      goto save_pc;
	    }

	  /* We've wandered out of the step range (but haven't done a
	     subroutine call or return).  */

	  sal = find_pc_line(stop_pc, 0);
	  
	  if (step_range_end == 1 ||	/* stepi or nexti */
	      sal.line == 0 ||		/* ...or no line # info */
	      (stop_pc == sal.pc	/* ...or we're at the start */
	       && current_line != sal.line)) {	/* of a different line */
	    /* Stop because we're done stepping.  */
	    stop_step = 1;
	    break;
	  } else {
	    /* We aren't done stepping, and we have line number info for $pc.
	       Optimize by setting the step_range for the line.  
	       (We might not be in the original line, but if we entered a
	       new line in mid-statement, we continue stepping.  This makes 
	       things like for(;;) statements work better.)  */
	    step_range_start = sal.pc;
	    step_range_end = sal.end;
	    goto save_pc;
	  }
	  /* We never fall through here */
	}

      if (trap_expected
	  && IN_SIGTRAMP (stop_pc, stop_func_name)
	  && !IN_SIGTRAMP (prev_pc, prev_func_name))
	{
	  /* What has happened here is that we have just stepped the inferior
	     with a signal (because it is a signal which shouldn't make
	     us stop), thus stepping into sigtramp.

	     So we need to set a step_resume_break_address breakpoint
	     and continue until we hit it, and then step.  */
	  step_resume_break_address = prev_pc;
	  /* Always 1, I think, but it's probably easier to have
	     the step_resume_break as usual rather than trying to
	     re-use the breakpoint which is already there.  */
	  step_resume_break_duplicate =
	    breakpoint_here_p (step_resume_break_address);
	  if (breakpoints_inserted)
	    insert_step_breakpoint ();
	  remove_breakpoints_on_following_step = 1;
	  another_trap = 1;
	}

/* My apologies to the gods of structured programming. */
/* Come to this label when you need to resume the inferior.  It's really much
   cleaner at this time to do a goto than to try and figure out what the
   if-else chain ought to look like!! */

    keep_going:

save_pc:
      /* Save the pc before execution, to compare with pc after stop.  */
      prev_pc = read_pc ();	/* Might have been DECR_AFTER_BREAK */
      prev_func_start = stop_func_start; /* Ok, since if DECR_PC_AFTER
					  BREAK is defined, the
					  original pc would not have
					  been at the start of a
					  function. */
      prev_func_name = stop_func_name;
      prev_sp = stop_sp;

      /* If we did not do break;, it means we should keep
	 running the inferior and not return to debugger.  */

      if (trap_expected && stop_signal != SIGTRAP)
	{
	  /* We took a signal (which we are supposed to pass through to
	     the inferior, else we'd have done a break above) and we
	     haven't yet gotten our trap.  Simply continue.  */
	  resume ((step_range_end && !step_resume_break_address)
		  || (trap_expected && !step_resume_break_address)
		  || bpstat_should_step (),
		  stop_signal);
	}
      else
	{
	  /* Either the trap was not expected, but we are continuing
	     anyway (the user asked that this signal be passed to the
	     child)
	       -- or --
	     The signal was SIGTRAP, e.g. it was our signal, but we
	     decided we should resume from it.

	     We're going to run this baby now!

	     Insert breakpoints now, unless we are trying
	     to one-proceed past a breakpoint.  */
	  /* If we've just finished a special step resume and we don't
	     want to hit a breakpoint, pull em out.  */
	  if (!step_resume_break_address &&
	      remove_breakpoints_on_following_step)
	    {
	      remove_breakpoints_on_following_step = 0;
	      remove_breakpoints ();
	      breakpoints_inserted = 0;
	    }
	  else if (!breakpoints_inserted &&
		   (step_resume_break_address != 0 || !another_trap))
	    {
	      insert_step_breakpoint ();
	      breakpoints_failed = insert_breakpoints ();
	      if (breakpoints_failed)
		break;
	      breakpoints_inserted = 1;
	    }

	  trap_expected = another_trap;

	  if (stop_signal == SIGTRAP)
	    stop_signal = 0;

#ifdef SHIFT_INST_REGS
	  /* I'm not sure when this following segment applies.  I do know, now,
	     that we shouldn't rewrite the regs when we were stopped by a
	     random signal from the inferior process.  */

          if (!bpstat_explains_signal (stop_bpstat)
	      && (stop_signal != SIGCLD) 
              && !stopped_by_random_signal)
            {
            CORE_ADDR pc_contents = read_register (PC_REGNUM);
            CORE_ADDR npc_contents = read_register (NPC_REGNUM);
            if (pc_contents != npc_contents)
              {
              write_register (NNPC_REGNUM, npc_contents);
              write_register (NPC_REGNUM, pc_contents);
	      }
            }
#endif /* SHIFT_INST_REGS */

	  resume ((!step_resume_break_address
		   && !handling_longjmp
		   && (step_range_end
		       || trap_expected))
		  || bpstat_should_step (),
		  stop_signal);
	}
    }

 stop_stepping:
  if (target_has_execution)
    {
      /* Assuming the inferior still exists, set these up for next
	 time, just like we did above if we didn't break out of the
	 loop.  */
      prev_pc = read_pc ();
      prev_func_start = stop_func_start;
      prev_func_name = stop_func_name;
      prev_sp = stop_sp;
    }
}

/* Here to return control to GDB when the inferior stops for real.
   Print appropriate messages, remove breakpoints, give terminal our modes.

   STOP_PRINT_FRAME nonzero means print the executing frame
   (pc, function, args, file, line number and line text).
   BREAKPOINTS_FAILED nonzero means stop was due to error
   attempting to insert breakpoints.  */

void
normal_stop ()
{
  char *tem;
  struct cmd_list_element *c;

  /* Make sure that the current_frame's pc is correct.  This
     is a correction for setting up the frame info before doing
     DECR_PC_AFTER_BREAK */
  if (target_has_execution)
    (get_current_frame ())->pc = read_pc ();
  
  if (breakpoints_failed)
    {
      target_terminal_ours_for_output ();
      print_sys_errmsg ("ptrace", breakpoints_failed);
      printf_filtered ("Stopped; cannot insert breakpoints.\n\
The same program may be running in another process.\n");
    }

  if (target_has_execution)
    remove_step_breakpoint ();

  if (target_has_execution && breakpoints_inserted)
    if (remove_breakpoints ())
      {
	target_terminal_ours_for_output ();
	printf_filtered ("Cannot remove breakpoints because program is no longer writable.\n\
It might be running in another process.\n\
Further execution is probably impossible.\n");
      }

  breakpoints_inserted = 0;

  /* Delete the breakpoint we stopped at, if it wants to be deleted.
     Delete any breakpoint that is to be deleted at the next stop.  */

  breakpoint_auto_delete (stop_bpstat);

  /* If an auto-display called a function and that got a signal,
     delete that auto-display to avoid an infinite recursion.  */

  if (stopped_by_random_signal)
    disable_current_display ();

  if (step_multi && stop_step)
    return;

  target_terminal_ours ();

  /* Look up the hook_stop and run it if it exists.  */

  if (stop_command->hook)
    {
      catch_errors (hook_stop_stub, (char *)stop_command->hook,
		    "Error while running hook_stop:\n");
    }

  if (!target_has_stack)
    return;

  /* Select innermost stack frame except on return from a stack dummy routine,
     or if the program has exited.  Print it without a level number if
     we have changed functions or hit a breakpoint.  Print source line
     if we have one.  */
  if (!stop_stack_dummy)
    {
      select_frame (get_current_frame (), 0);

      if (stop_print_frame)
	{
	  int source_only;

	  source_only = bpstat_print (stop_bpstat);
	  source_only = source_only ||
	        (   stop_step
		 && step_frame_address == stop_frame_address
		 && step_start_function == find_pc_function (stop_pc));

          print_stack_frame (selected_frame, -1, source_only? -1: 1);

	  /* Display the auto-display expressions.  */
	  do_displays ();
	}
    } else {
      /* Pop the empty frame that contains the stack dummy.
         POP_FRAME ends with a setting of the current frame, so we
	 can use that next. */
#ifndef NEW_CALL_FUNCTION
      POP_FRAME;
#endif
      select_frame (get_current_frame (), 0);
    }
}

static int
hook_stop_stub (cmd)
     char *cmd;
{
  execute_user_command ((struct cmd_list_element *)cmd, 0);
}


static void
insert_step_breakpoint ()
{
  if (step_resume_break_address && !step_resume_break_duplicate)
    target_insert_breakpoint (step_resume_break_address,
			      step_resume_break_shadow);
}

static void
remove_step_breakpoint ()
{
  if (step_resume_break_address && !step_resume_break_duplicate)