Re: [RFA] Stop infrun from tracking breakpoint insertion status.

[Vladimir Prus <vladimir at codesourcery dot com>]

On Monday 26 November 2007 18:24:56 Ulrich Weigand wrote:
> Vladimir Prus wrote:
> 
> > On Thursday 22 November 2007 03:49:22 you wrote:
> > > Hmmm, if it helps, I could run a test on AIX, which does use
> > > TARGET_WAITKIND_LOADED.
> > 
> > That would surely help in convincing ourself the patch don't
> > break anything.
> 
> I did a test run on AIX now, and unfortunately it did break.
> 
> I didn't look into the failure in detail, but apparently it
> is unrelated to TARGET_WAITKIND_LOADED, but rather to software
> single-step support:

The second problem was that breakpoint_inserted_here_p checks for
both ordinary breakpoints and single step breakpoints (which don't
go on bp_location_chain). In most cases, it does not matter, but
in one place the code tries to figure if we're stopped on a single
step breakpoint or an ordinary one, and surely, breakpoint_inserted_here_p
returning 1 for both cases was not good.

The attached revision of the patch introduces a separate
regular_breakpoint_inserted_here_p function. No regressions on
either x86 or arm-linux. OK?

- Volodya

	The checks of breakpoints_inserted before calling remove_breakpoints
	are removed, as remove_breakpoint won't touch uninserted breakpoints.
	In a number of places, we're interested if a breakpoint is inserted
	at particular PC, and we now use breakpoint_inserted_here_p.  In a few
	places, insert_breakpoints can be called unconditionally, since it
	won't try to insert already inserted breakpoint.

        * breakpoint.h (regular_breakpoint_inserted_here_p): New
        declaration.
        * breakpoint.c (regular_breakpoint_inserted_here_p): New.
        (breakpoint_inserted_here_p): Use
        regular_breakpoint_inserted_here_p.
        * infrun.c (breakpoints_inserted): Remove.
        (resume): Don't check for breakpoints_inserted before
        remove_hw_watchpoints. Use breakpoint_inserted_here_p.
        (proceed, init_wait_for_inferior): Don't set breakpoints_inserted.
        (handle_inferior_event): Don't use breakpoints_inserted.
        Use breakpoints_meant_to_be_inserted and
        breakpoints_inserted_here_p.
        (insert_step_resume_breakpoint_at_sal, keep_going): Use
        breakpoints_meant_to_be_inserted. Don't set breakpoints_inserted.
        (normal_stop): Don't check for breakpoints_inserted.  Don't
        set breakpoints_inserted.
        (keep_going): Don't check for breakpoints_inserted.
        (insert_step_resume_breakpoint_at_sal): Don't insert
        breakpoints
---
 gdb/breakpoint.c |   21 ++++++++++++++----
 gdb/breakpoint.h |    2 +
 gdb/infrun.c     |   59 +++++++++++++++--------------------------------------
 3 files changed, 35 insertions(+), 47 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 2203f6e..2717302 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -1757,12 +1757,13 @@ breakpoint_here_p (CORE_ADDR pc)
 }
 
 
-/* breakpoint_inserted_here_p (PC) is just like breakpoint_here_p(),
-   but it only returns true if there is actually a breakpoint inserted
-   at PC.  */
+/* Returns non-zero if there's a breakpoint inserted at PC, which is
+   inserted using regular breakpoint_chain/bp_location_chain mechanism.
+   This does not check for single-step breakpoints, which are
+   inserted and removed using direct target manipulation.  */
 
 int
-breakpoint_inserted_here_p (CORE_ADDR pc)
+regular_breakpoint_inserted_here_p (CORE_ADDR pc)
 {
   const struct bp_location *bpt;
 
@@ -1783,8 +1784,18 @@ breakpoint_inserted_here_p (CORE_ADDR pc)
            return 1;
        }
     }
+  return 0;
+}
+
+/* Returns non-zero iff there's either regular breakpoint
+   or a single step breakpoint inserted at PC.  */
+
+int
+breakpoint_inserted_here_p (CORE_ADDR pc)
+{
+  if (regular_breakpoint_inserted_here_p (pc))
+    return 1;
 
-  /* Also check for software single-step breakpoints.  */
   if (single_step_breakpoint_inserted_here_p (pc))
     return 1;
 
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index e4aa72a..4b84502 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -674,6 +674,8 @@ extern enum breakpoint_here breakpoint_here_p (CORE_ADDR);
 
 extern int breakpoint_inserted_here_p (CORE_ADDR);
 
+extern int regular_breakpoint_inserted_here_p (CORE_ADDR);
+
 extern int software_breakpoint_inserted_here_p (CORE_ADDR);
 
 extern int breakpoint_thread_match (CORE_ADDR, ptid_t);
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 00cd2a5..c357f27 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -214,10 +214,6 @@ static unsigned char *signal_program;
 
 static struct cmd_list_element *stop_command;
 
-/* Nonzero if breakpoints are now inserted in the inferior.  */
-
-static int breakpoints_inserted;
-
 /* Function inferior was in as of last step command.  */
 
 static struct symbol *step_start_function;
@@ -519,7 +515,7 @@ resume (int step, enum target_signal sig)
      Work around the problem by removing hardware watchpoints if a step is
      requested, GDB will check for a hardware watchpoint trigger after the
      step anyway.  */
-  if (CANNOT_STEP_HW_WATCHPOINTS && step && breakpoints_inserted)
+  if (CANNOT_STEP_HW_WATCHPOINTS && step)
     remove_hw_watchpoints ();
 
 
@@ -635,7 +631,7 @@ a command like `return' or `jump' to continue execution."));
          /* Most targets can step a breakpoint instruction, thus
             executing it normally.  But if this one cannot, just
             continue and we will hit it anyway.  */
-         if (step && breakpoints_inserted && breakpoint_here_p (read_pc ()))
+         if (step && breakpoint_inserted_here_p (read_pc ()))
            step = 0;
        }
       target_resume (resume_ptid, step, sig);
@@ -784,12 +780,7 @@ proceed (CORE_ADDR addr, enum target_signal siggnal, int step)
        Continue it automatically and insert breakpoints then.  */
     trap_expected = 1;
   else
-    {
-      insert_breakpoints ();
-      /* If we get here there was no call to error() in 
-         insert breakpoints -- so they were inserted.  */
-      breakpoints_inserted = 1;
-    }
+    insert_breakpoints ();
 
   if (siggnal != TARGET_SIGNAL_DEFAULT)
     stop_signal = siggnal;
@@ -885,7 +876,6 @@ init_wait_for_inferior (void)
   /* These are meaningless until the first time through wait_for_inferior.  */
   prev_pc = 0;
 
-  breakpoints_inserted = 0;
   breakpoint_init_inferior (inf_starting);
 
   /* Don't confuse first call to proceed(). */
@@ -1335,10 +1325,7 @@ handle_inferior_event (struct execution_control_state *ecs)
 
          /* Remove breakpoints, SOLIB_ADD might adjust
             breakpoint addresses via breakpoint_re_set.  */
-         breakpoints_were_inserted = breakpoints_inserted;
-         if (breakpoints_inserted)
-           remove_breakpoints ();
-         breakpoints_inserted = 0;
+         remove_breakpoints ();
 
          /* Check for any newly added shared libraries if we're
             supposed to be adding them automatically.  Switch
@@ -1381,11 +1368,7 @@ handle_inferior_event (struct execution_control_state *ecs)
             for "catch load".  */
 
          /* Reinsert breakpoints and continue.  */
-         if (breakpoints_were_inserted)
-           {
-             insert_breakpoints ();
-             breakpoints_inserted = 1;
-           }
+         insert_breakpoints ();
        }
 
       /* If we are skipping through a shell, or through shared library
@@ -1671,7 +1654,7 @@ handle_inferior_event (struct execution_control_state *ecs)
       /* Check if a regular breakpoint has been hit before checking
          for a potential single step breakpoint. Otherwise, GDB will
          not see this breakpoint hit when stepping onto breakpoints.  */
-      if (breakpoints_inserted && breakpoint_here_p (stop_pc))
+      if (regular_breakpoint_inserted_here_p (stop_pc))
        {
          ecs->random_signal = 0;
          if (!breakpoint_thread_match (stop_pc, ecs->ptid))
@@ -1784,7 +1767,6 @@ handle_inferior_event (struct execution_control_state *ecs)
            }
          else
            {                   /* Single step */
-             breakpoints_inserted = 0;
              if (!ptid_equal (inferior_ptid, ecs->ptid))
                context_switch (ecs);
              ecs->waiton_ptid = ecs->ptid;
@@ -1946,7 +1928,7 @@ handle_inferior_event (struct execution_control_state *ecs)
      stack.  */
 
   if (stop_signal == TARGET_SIGNAL_TRAP
-      || (breakpoints_inserted
+      || (breakpoint_inserted_here_p (stop_pc)
          && (stop_signal == TARGET_SIGNAL_ILL
              || stop_signal == TARGET_SIGNAL_SEGV
              || stop_signal == TARGET_SIGNAL_EMT))
@@ -2077,8 +2059,8 @@ process_event_stop_test:
        stop_signal = TARGET_SIGNAL_0;
 
       if (prev_pc == read_pc ()
-         && !breakpoints_inserted
          && breakpoint_here_p (read_pc ())
+         && !breakpoint_inserted_here_p (read_pc ())
          && step_resume_breakpoint == NULL)
        {
          /* We were just starting a new sequence, attempting to
@@ -2151,7 +2133,6 @@ process_event_stop_test:
          fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME\n");
        disable_longjmp_breakpoint ();
        remove_breakpoints ();
-       breakpoints_inserted = 0;
        if (!gdbarch_get_longjmp_target_p (current_gdbarch)
            || !gdbarch_get_longjmp_target (current_gdbarch,
                                            get_current_frame (), &jmp_buf_pc))
@@ -2177,7 +2158,6 @@ process_event_stop_test:
         if (debug_infrun)
          fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_CLEAR_LONGJMP_RESUME\n");
        remove_breakpoints ();
-       breakpoints_inserted = 0;
        disable_longjmp_breakpoint ();
        ecs->handling_longjmp = 0;      /* FIXME */
        if (what.main_action == BPSTAT_WHAT_CLEAR_LONGJMP_RESUME)
@@ -2187,9 +2167,7 @@ process_event_stop_test:
       case BPSTAT_WHAT_SINGLE:
         if (debug_infrun)
          fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_SINGLE\n");
-       if (breakpoints_inserted)
-         remove_breakpoints ();
-       breakpoints_inserted = 0;
+       remove_breakpoints ();
        ecs->another_trap = 1;
        /* Still need to check other stuff, at least the case
           where we are stepping and step out of the right range.  */
@@ -2251,7 +2229,6 @@ process_event_stop_test:
               to doing that.  */
            ecs->step_after_step_resume_breakpoint = 0;
            remove_breakpoints ();
-           breakpoints_inserted = 0;
            ecs->another_trap = 1;
            keep_going (ecs);
            return;
@@ -2266,9 +2243,7 @@ process_event_stop_test:
          /* Remove breakpoints, we eventually want to step over the
             shlib event breakpoint, and SOLIB_ADD might adjust
             breakpoint addresses via breakpoint_re_set.  */
-         if (breakpoints_inserted)
-           remove_breakpoints ();
-         breakpoints_inserted = 0;
+         remove_breakpoints ();
 
          /* Check for any newly added shared libraries if we're
             supposed to be adding them automatically.  Switch
@@ -2871,8 +2846,6 @@ insert_step_resume_breakpoint_at_sal (struct symtab_and_line sr_sal,
 
   step_resume_breakpoint = set_momentary_breakpoint (sr_sal, sr_id,
                                                     bp_step_resume);
-  if (breakpoints_inserted)
-    insert_breakpoints ();
 }
 
 /* Insert a "step-resume breakpoint" at RETURN_FRAME.pc.  This is used
@@ -2969,9 +2942,13 @@ keep_going (struct execution_control_state *ecs)
          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!  */
+         We're going to run this baby now!  
 
-      if (!breakpoints_inserted && !ecs->another_trap)
+        Note that insert_breakpoints won't try to re-insert
+        already inserted breakpoints.  Therefore, we don't
+        care if breakpoints were already inserted, or not.  */
+      
+      if (!ecs->another_trap)
        {
          /* Stop stepping when inserting breakpoints
             has failed.  */
@@ -2980,7 +2957,6 @@ keep_going (struct execution_control_state *ecs)
              stop_stepping (ecs);
              return;
            }
-         breakpoints_inserted = 1;
        }
 
       trap_expected = ecs->another_trap;
@@ -3173,7 +3149,7 @@ normal_stop (void)
        gdbarch_decr_pc_after_break needs to just go away.  */
     deprecated_update_frame_pc_hack (get_current_frame (), read_pc ());
 
-  if (target_has_execution && breakpoints_inserted)
+  if (target_has_execution)
     {
       if (remove_breakpoints ())
        {
@@ -3184,7 +3160,6 @@ 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.  */
-- 
1.5.3.5