* stabs.texinfo: N_MAIN is sometimes used for C.
[deliverable/binutils-gdb.git] / gdb / infrun.c
index ab4e3e0f986c4c961e22093219396829afe4d5c7..30ab10033ab493a672921953250a92b054d3cced 100644 (file)
@@ -1,5 +1,6 @@
 /* Target-struct-independent code to start (run) and stop an inferior process.
-   Copyright 1986, 1987, 1988, 1989, 1991, 1992 Free Software Foundation, Inc.
+   Copyright 1986, 1987, 1988, 1989, 1991, 1992, 1993
+   Free Software Foundation, Inc.
 
 This file is part of GDB.
 
@@ -136,34 +137,12 @@ sig_print_info PARAMS ((int));
 static void
 sig_print_header PARAMS ((void));
 
-static void
-remove_step_breakpoint PARAMS ((void));
-
-static void
-insert_step_breakpoint PARAMS ((void));
-
 static void
 resume_cleanups PARAMS ((int));
 
 static int
 hook_stop_stub PARAMS ((char *));
 
-/* Sigtramp is a routine that the kernel calls (which then calls the
-   signal handler).  On most machines it is a library routine that
-   is linked into the executable.
-
-   This macro, given a program counter value and the name of the
-   function in which that PC resides (which can be null if the
-   name is not known), returns nonzero if the PC and name show
-   that we are in sigtramp.
-
-   On most machines just see if the name is sigtramp (and if we have
-   no name, assume we are not in sigtramp).  */
-#if !defined (IN_SIGTRAMP)
-#define IN_SIGTRAMP(pc, name) \
-  (name && !strcmp ("_sigtramp", name))
-#endif
-
 /* GET_LONGJMP_TARGET returns the PC at which longjmp() will resume the
    program.  It needs to examine the jmp_buf argument and extract the PC
    from it.  The return value is non-zero on success, zero otherwise. */
@@ -196,12 +175,6 @@ hook_stop_stub PARAMS ((char *));
 #define INSTRUCTION_NULLIFIED 0
 #endif
 
-#ifdef TDESC
-#include "tdesc.h"
-int safe_to_init_tdesc_context = 0;
-extern dc_dcontext_t current_context;
-#endif
-
 /* Tables of how to react to signals; the user sets them.  */
 
 static unsigned char *signal_stop;
@@ -237,19 +210,6 @@ static int breakpoints_inserted;
 
 static struct symbol *step_start_function;
 
-/* Nonzero => address for special breakpoint for resuming stepping.  */
-
-static CORE_ADDR step_resume_break_address;
-
-/* Pointer to orig contents of the byte where the special breakpoint is.  */
-
-static char step_resume_break_shadow[BREAKPOINT_MAX];
-
-/* Nonzero means the special breakpoint is a duplicate
-   so it has not itself been inserted.  */
-
-static int step_resume_break_duplicate;
-
 /* Nonzero if we are expecting a trace trap and should proceed from it.  */
 
 static int trap_expected;
@@ -356,7 +316,6 @@ clear_proceed_status ()
   step_range_end = 0;
   step_frame_address = 0;
   step_over_calls = -1;
-  step_resume_break_address = 0;
   stop_after_trap = 0;
   stop_soon_quietly = 0;
   proceed_to_finish = 0;
@@ -401,15 +360,7 @@ proceed (addr, siggnal, step)
        oneproc = 1;
     }
   else
-    {
-      write_register (PC_REGNUM, addr);
-#ifdef NPC_REGNUM
-      write_register (NPC_REGNUM, addr + 4);
-#ifdef NNPC_REGNUM
-      write_register (NNPC_REGNUM, addr + 8);
-#endif
-#endif
-    }
+    write_pc (addr);
 
   if (trap_expected_after_continue)
     {
@@ -497,7 +448,14 @@ init_wait_for_inferior ()
   stop_signal = 0;             /* Don't confuse first call to proceed(). */
 }
 
-
+static void
+delete_breakpoint_current_contents (arg)
+     PTR arg;
+{
+  struct breakpoint **breakpointp = (struct breakpoint **)arg;
+  if (*breakpointp != NULL)
+    delete_breakpoint (*breakpointp);
+}
 \f
 /* Wait for control to return from inferior to debugger.
    If inferior gets a signal, we may decide to start it up again
@@ -508,6 +466,7 @@ init_wait_for_inferior ()
 void
 wait_for_inferior ()
 {
+  struct cleanup *old_cleanups;
   WAITTYPE w;
   int another_trap;
   int random_signal;
@@ -515,13 +474,15 @@ wait_for_inferior ()
   CORE_ADDR stop_func_start;
   char *stop_func_name;
   CORE_ADDR prologue_pc, tmp;
-  int stop_step_resume_break;
   struct symtab_and_line sal;
   int remove_breakpoints_on_following_step = 0;
   int current_line;
   int handling_longjmp = 0;    /* FIXME */
   struct symtab *symtab;
+  struct breakpoint *step_resume_breakpoint = NULL;
 
+  old_cleanups = make_cleanup (delete_breakpoint_current_contents,
+                              &step_resume_breakpoint);
   sal = find_pc_line(prev_pc, 0);
   current_line = sal.line;
 
@@ -562,6 +523,8 @@ wait_for_inferior ()
        }
       else if (!WIFSTOPPED (w))
        {
+         char *signame;
+         
          stop_print_frame = 0;
          stop_signal = WTERMSIG (w);
          target_terminal_ours ();      /* Must do this before mourn anyway */
@@ -570,10 +533,16 @@ wait_for_inferior ()
          printf_filtered ("\nProgram terminated: ");
          PRINT_RANDOM_SIGNAL (stop_signal);
 #else
-         printf_filtered ("\nProgram terminated with signal %d, %s\n",
-                          stop_signal, safe_strsignal (stop_signal));
+         printf_filtered ("\nProgram terminated with signal ");
+         signame = strsigno (stop_signal);
+         if (signame == NULL)
+           printf_filtered ("%d", stop_signal);
+         else
+           /* Do we need to print the number in addition to the name?  */
+           printf_filtered ("%s (%d)", signame, stop_signal);
+         printf_filtered (", %s\n", safe_strsignal (stop_signal));
 #endif
-         printf_filtered ("The inferior process no longer exists.\n");
+         printf_filtered ("The program no longer exists.\n");
          fflush (stdout);
 #ifdef NO_SINGLE_STEP
          one_stepped = 0;
@@ -596,11 +565,11 @@ wait_for_inferior ()
        }
 
       stop_pc = read_pc ();
-      set_current_frame ( create_new_frame (read_register (FP_REGNUM),
+      set_current_frame ( create_new_frame (read_fp (),
                                            read_pc ()));
-      
+
       stop_frame_address = FRAME_FP (get_current_frame ());
-      stop_sp = read_register (SP_REGNUM);
+      stop_sp = read_sp ();
       stop_func_start = 0;
       stop_func_name = 0;
       /* Don't care about return value; stop_func_start and stop_func_name
@@ -612,7 +581,6 @@ wait_for_inferior ()
       stop_step = 0;
       stop_stack_dummy = 0;
       stop_print_frame = 1;
-      stop_step_resume_break = 0;
       random_signal = 0;
       stopped_by_random_signal = 0;
       breakpoints_failed = 0;
@@ -655,11 +623,11 @@ wait_for_inferior ()
             if just proceeded over a breakpoint.
 
             However, if we are trying to proceed over a breakpoint
-            and end up in sigtramp, then step_resume_break_address
+            and end up in sigtramp, then step_resume_breakpoint
             will be set and we should check whether we've hit the
             step breakpoint.  */
          if (stop_signal == SIGTRAP && trap_expected
-             && step_resume_break_address == 0)
+             && step_resume_breakpoint == NULL)
            bpstat_clear (&stop_bpstat);
          else
            {
@@ -673,48 +641,28 @@ wait_for_inferior ()
                 the address of the breakpoint before the current pc.  */
              if (prev_pc == stop_pc - DECR_PC_AFTER_BREAK
                  || !step_range_end
-                 || step_resume_break_address
+                 || step_resume_breakpoint != NULL
                  || handling_longjmp /* FIXME */)
 #endif /* DECR_PC_AFTER_BREAK not zero */
                {
-                 /* See if we stopped at the special breakpoint for
-                    stepping over a subroutine call.  If both are zero,
-                    this wasn't the reason for the stop.  */
-                 if (step_resume_break_address
-                     && stop_pc - DECR_PC_AFTER_BREAK
-                        == step_resume_break_address)
-                   {
-                     stop_step_resume_break = 1;
-                     if (DECR_PC_AFTER_BREAK)
-                       {
-                         stop_pc -= DECR_PC_AFTER_BREAK;
-                         write_register (PC_REGNUM, stop_pc);
-                         pc_changed = 0;
-                       }
-                   }
-                 else
-                   {
-                     stop_bpstat =
-                       bpstat_stop_status (&stop_pc, stop_frame_address);
-                     /* Following in case break condition called a
-                        function.  */
-                     stop_print_frame = 1;
-                   }
+                 stop_bpstat =
+                   bpstat_stop_status (&stop_pc, stop_frame_address);
+                 /* Following in case break condition called a
+                    function.  */
+                 stop_print_frame = 1;
                }
            }
-         
+
          if (stop_signal == SIGTRAP)
            random_signal
              = !(bpstat_explains_signal (stop_bpstat)
                  || trap_expected
-                 || stop_step_resume_break
                  || PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address)
-                 || (step_range_end && !step_resume_break_address));
+                 || (step_range_end && step_resume_breakpoint == NULL));
          else
            {
              random_signal
                = !(bpstat_explains_signal (stop_bpstat)
-                   || stop_step_resume_break
                    /* End of a stack dummy.  Some systems (e.g. Sony
                       news) give another signal besides SIGTRAP,
                       so check here as well as above.  */
@@ -726,10 +674,10 @@ wait_for_inferior ()
        }
       else
        random_signal = 1;
-      
+
       /* For the program's own signals, act according to
         the signal handling tables.  */
-      
+
       if (random_signal)
        {
          /* Signal not for debugging purposes.  */
@@ -740,13 +688,20 @@ wait_for_inferior ()
          if (stop_signal >= NSIG
              || signal_print[stop_signal])
            {
+             char *signame;
              printed = 1;
              target_terminal_ours_for_output ();
 #ifdef PRINT_RANDOM_SIGNAL
              PRINT_RANDOM_SIGNAL (stop_signal);
 #else
-             printf_filtered ("\nProgram received signal %d, %s\n",
-                              stop_signal, safe_strsignal (stop_signal));
+             printf_filtered ("\nProgram received signal ");
+             signame = strsigno (stop_signal);
+             if (signame == NULL)
+               printf_filtered ("%d", stop_signal);
+             else
+               /* Do we need to print the number as well as the name?  */
+               printf_filtered ("%s (%d)", signame, stop_signal);
+             printf_filtered (", %s\n", safe_strsignal (stop_signal));
 #endif /* PRINT_RANDOM_SIGNAL */
              fflush (stdout);
            }
@@ -758,129 +713,109 @@ wait_for_inferior ()
          else if (printed)
            target_terminal_inferior ();
 
-         /* Note that virtually all the code below does `if !random_signal'.
-            Perhaps this code should end with a goto or continue.  At least
-            one (now fixed) bug was caused by this -- a !random_signal was
-            missing in one of the tests below.  */
+         /* Clear the signal if it should not be passed.  */
+         if (signal_program[stop_signal] == 0)
+           stop_signal = 0;
+
+         /* I'm not sure whether this needs to be check_sigtramp2 or
+            whether it could/should be keep_going.  */
+         goto check_sigtramp2;
        }
 
       /* Handle cases caused by hitting a breakpoint.  */
+      {
+       CORE_ADDR jmp_buf_pc;
+       struct bpstat_what what;
 
-      if (!random_signal)
-       if (bpstat_explains_signal (stop_bpstat))
-         {
-           CORE_ADDR jmp_buf_pc;
+       what = bpstat_what (stop_bpstat);
 
-           switch (stop_bpstat->breakpoint_at->type) /* FIXME */
+       switch (what.main_action)
+         {
+         case BPSTAT_WHAT_SET_LONGJMP_RESUME:
+           /* If we hit the breakpoint at longjmp, disable it for the
+              duration of this command.  Then, install a temporary
+              breakpoint at the target of the jmp_buf. */
+           disable_longjmp_breakpoint();
+           remove_breakpoints ();
+           breakpoints_inserted = 0;
+           if (!GET_LONGJMP_TARGET(&jmp_buf_pc)) goto keep_going;
+
+           /* Need to blow away step-resume breakpoint, as it
+              interferes with us */
+           if (step_resume_breakpoint != NULL)
              {
-               /* If we hit the breakpoint at longjmp, disable it for the
-                  duration of this command.  Then, install a temporary
-                  breakpoint at the target of the jmp_buf. */
-             case bp_longjmp:
-               disable_longjmp_breakpoint();
-               remove_breakpoints ();
-               breakpoints_inserted = 0;
-               if (!GET_LONGJMP_TARGET(&jmp_buf_pc)) goto keep_going;
-
-               /* Need to blow away step-resume breakpoint, as it
-                  interferes with us */
-               remove_step_breakpoint ();
-               step_resume_break_address = 0;
-               stop_step_resume_break = 0;
-
-#if 0                          /* FIXME - Need to implement nested temporary breakpoints */
-               if (step_over_calls > 0)
-                 set_longjmp_resume_breakpoint(jmp_buf_pc,
-                                               get_current_frame());
-               else
+               delete_breakpoint (step_resume_breakpoint);
+               step_resume_breakpoint = NULL;
+               what.step_resume = 0;
+             }
+
+#if 0
+           /* FIXME - Need to implement nested temporary breakpoints */
+           if (step_over_calls > 0)
+             set_longjmp_resume_breakpoint(jmp_buf_pc,
+                                           get_current_frame());
+           else
 #endif                         /* 0 */
-                 set_longjmp_resume_breakpoint(jmp_buf_pc, NULL);
-               handling_longjmp = 1; /* FIXME */
+             set_longjmp_resume_breakpoint(jmp_buf_pc, NULL);
+           handling_longjmp = 1; /* FIXME */
+           goto keep_going;
+
+         case BPSTAT_WHAT_CLEAR_LONGJMP_RESUME:
+         case BPSTAT_WHAT_CLEAR_LONGJMP_RESUME_SINGLE:
+           remove_breakpoints ();
+           breakpoints_inserted = 0;
+#if 0
+           /* FIXME - Need to implement nested temporary breakpoints */
+           if (step_over_calls
+               && (stop_frame_address
+                   INNER_THAN step_frame_address))
+             {
+               another_trap = 1;
                goto keep_going;
-
-             case bp_longjmp_resume:
-               remove_breakpoints ();
-               breakpoints_inserted = 0;
-#if 0                          /* FIXME - Need to implement nested temporary breakpoints */
-               if (step_over_calls
-                   && (stop_frame_address
-                       INNER_THAN step_frame_address))
-                 {
-                   another_trap = 1;
-                   goto keep_going;
-                 }
+             }
 #endif                         /* 0 */
-               disable_longjmp_breakpoint();
-               handling_longjmp = 0; /* FIXME */
-               break;
+           disable_longjmp_breakpoint();
+           handling_longjmp = 0; /* FIXME */
+           if (what.main_action == BPSTAT_WHAT_CLEAR_LONGJMP_RESUME)
+             break;
+           /* else fallthrough */
 
-             default:
-               fprintf(stderr, "Unknown breakpoint type %d\n",
-                       stop_bpstat->breakpoint_at->type);
-             case bp_watchpoint:
-             case bp_breakpoint:
-             case bp_until:
-             case bp_finish:
-               /* Does a breakpoint want us to stop?  */
-               if (bpstat_stop (stop_bpstat))
-                 {
-                   stop_print_frame = bpstat_should_print (stop_bpstat);
-                   goto stop_stepping;
-                 }
-               /* Otherwise, must remove breakpoints and single-step
-                  to get us past the one we hit.  */
-               else
-                 {
-                   remove_breakpoints ();
-                   remove_step_breakpoint ();
-                   breakpoints_inserted = 0;
-                   another_trap = 1;
-                 }
-               break;
-             }
+         case BPSTAT_WHAT_SINGLE:
+           if (breakpoints_inserted)
+             remove_breakpoints ();
+           breakpoints_inserted = 0;
+           another_trap = 1;
+           /* Still need to check other stuff, at least the case
+              where we are stepping and step out of the right range.  */
+           break;
+
+         case BPSTAT_WHAT_STOP_NOISY:
+           stop_print_frame = 1;
+           /* We are about to nuke the step_resume_breakpoint via the
+              cleanup chain, so no need to worry about it here.  */
+           goto stop_stepping;
+
+         case BPSTAT_WHAT_STOP_SILENT:
+           stop_print_frame = 0;
+           /* We are about to nuke the step_resume_breakpoint via the
+              cleanup chain, so no need to worry about it here.  */
+           goto stop_stepping;
+
+         case BPSTAT_WHAT_KEEP_CHECKING:
+           break;
          }
-       else if (stop_step_resume_break)
+
+       if (what.step_resume)
          {
-           /* But if we have hit the step-resumption breakpoint,
-              remove it.  It has done its job getting us here.
-              The sp test is to make sure that we don't get hung
-              up in recursive calls in functions without frame
-              pointers.  If the stack pointer isn't outside of
-              where the breakpoint was set (within a routine to be
-              stepped over), we're in the middle of a recursive
-              call. Not true for reg window machines (sparc)
-              because the must change frames to call things and
-              the stack pointer doesn't have to change if it
-              the bp was set in a routine without a frame (pc can
-              be stored in some other window).
-              
-              The removal of the sp test is to allow calls to
-              alloca.  Nasty things were happening.  Oh, well,
-              gdb can only handle one level deep of lack of
-              frame pointer. */
-
-           /*
-             Disable test for step_frame_address match so that we always stop even if the
-             frames don't match.  Reason: if we hit the step_resume_breakpoint, there is
-             no way to temporarily disable it so that we can step past it.  If we leave
-             the breakpoint in, then we loop forever repeatedly hitting, but never
-             getting past the breakpoint.  This change keeps nexting over recursive
-             function calls from hanging gdb.
-             */
-#if 0
-           if (* step_frame_address == 0
-               || (step_frame_address == stop_frame_address))
-#endif
-             {
-               remove_step_breakpoint ();
-               step_resume_break_address = 0;
+           delete_breakpoint (step_resume_breakpoint);
+           step_resume_breakpoint = NULL;
 
-               /* If were waiting for a trap, hitting the step_resume_break
-                  doesn't count as getting it.  */
-               if (trap_expected)
-                 another_trap = 1;
-             }
+           /* If were waiting for a trap, hitting the step_resume_break
+              doesn't count as getting it.  */
+           if (trap_expected)
+             another_trap = 1;
          }
+      }
 
       /* We come here if we hit a breakpoint but should not
         stop for it.  Possibly we also were stepping
@@ -890,8 +825,7 @@ wait_for_inferior ()
 
       /* If this is the breakpoint at the end of a stack dummy,
         just stop silently.  */
-      if (!random_signal 
-        && PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address))
+      if (PC_IN_CALL_DUMMY (stop_pc, stop_sp, stop_frame_address))
          {
            stop_print_frame = 0;
            stop_stack_dummy = 1;
@@ -901,182 +835,241 @@ wait_for_inferior ()
            break;
          }
       
-      if (step_resume_break_address)
+      if (step_resume_breakpoint)
        /* Having a step-resume breakpoint overrides anything
           else having to do with stepping commands until
           that breakpoint is reached.  */
-       ;
+       /* I suspect this could/should be keep_going, because if the
+          check_sigtramp2 check succeeds, then it will put in another
+          step_resume_breakpoint, and we aren't (yet) prepared to nest
+          them.  */
+       goto check_sigtramp2;
+
+      if (step_range_end == 0)
+       /* Likewise if we aren't even stepping.  */
+       /* I'm not sure whether this needs to be check_sigtramp2 or
+          whether it could/should be keep_going.  */
+       goto check_sigtramp2;
+
       /* 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)))
+      if (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 might be doing a BPSTAT_WHAT_SINGLE and getting a signal.
+            So definately need to check for sigtramp here.  */
+         goto check_sigtramp2;
        }
-      
+
       /* 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)
+
+      /* Did we just take a signal?  */
+      if (IN_SIGTRAMP (stop_pc, stop_func_name)
+         && !IN_SIGTRAMP (prev_pc, prev_func_name))
        {
-         if (stop_func_start)
-           {
-             prologue_pc = stop_func_start;
-             SKIP_PROLOGUE (prologue_pc);
-           }
+         /* 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.  */
+         {
+           struct symtab_and_line sr_sal;
+
+           sr_sal.pc = prev_pc;
+           sr_sal.symtab = NULL;
+           sr_sal.line = 0;
+           step_resume_breakpoint =
+             set_momentary_breakpoint (sr_sal, get_current_frame (),
+                                       bp_step_resume);
+           if (breakpoints_inserted)
+             insert_breakpoints ();
+         }
 
-         /* 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;
-           }
+         /* If this is stepi or nexti, make sure that the stepping range
+            gets us past that instruction.  */
+         if (step_range_end == 1)
+           /* FIXME: Does this run afoul of the code below which, if
+              we step into the middle of a line, resets the stepping
+              range?  */
+           step_range_end = (step_range_start = prev_pc) + 1;
 
-         /* ==> 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;
-               }
+         remove_breakpoints_on_following_step = 1;
+         goto keep_going;
+       }
+
+      if (stop_func_start)
+       {
+         /* Do this after the IN_SIGTRAMP check; it might give
+            an error.  */
+         prologue_pc = stop_func_start;
+         SKIP_PROLOGUE (prologue_pc);
+       }
 
-             if (step_over_calls > 0)
-               goto step_over_function;
+      /* ==> See comments at top of file on this algorithm.  <==*/
 
-             tmp = SKIP_TRAMPOLINE_CODE (stop_pc);
-             if (tmp != 0)
-               stop_func_start = tmp;
+      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.  */
+
+         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
+                ("stepi").  Just stop.  */
+             stop_step = 1;
+             break;
+           }
+
+         if (step_over_calls > 0)
+           /* We're doing a "next".  */
+           goto step_over_function;
+
+         /* If we are in a function call trampoline (a stub between
+            the calling routine and the real function), locate the real
+            function.  That's what tells us (a) whether we want to step
+            into it at all, and (b) what prologue we want to run to
+            the end of, if we do step into it.  */
+         tmp = SKIP_TRAMPOLINE_CODE (stop_pc);
+         if (tmp != 0)
+           stop_func_start = tmp;
+
+         /* If we have line number information for the function we
+            are thinking of stepping into, step into it.
+
+            If there are several symtabs at that PC (e.g. with include
+            files), just want to know whether *any* of them have line
+            numbers.  find_pc_line handles this.  */
+         {
+           struct symtab_and_line tmp_sal;
 
-             symtab = find_pc_symtab (stop_func_start);
-             if (symtab && LINETABLE (symtab))
-               goto step_into_function;
+           tmp_sal = find_pc_line (stop_func_start, 0);
+           if (tmp_sal.line != 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;
+         /* A subroutine call has happened.  */
+         {
+           /* Set a special breakpoint after the return */
+           struct symtab_and_line sr_sal;
+           sr_sal.pc = 
+             ADDR_BITS_REMOVE
+               (SAVED_PC_AFTER_CALL (get_current_frame ()));
+           sr_sal.symtab = NULL;
+           sr_sal.line = 0;
+           step_resume_breakpoint =
+             set_momentary_breakpoint (sr_sal, get_current_frame (),
+                                       bp_step_resume);
+           if (breakpoints_inserted)
+             insert_breakpoints ();
+         }
+         goto keep_going;
 
 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.  */
+         /* 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.  */
+         /* 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;
+         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;
+         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. */
+           {
+             struct symtab_and_line sr_sal;
+
+             sr_sal.pc = stop_func_start;
+             sr_sal.symtab = NULL;
+             sr_sal.line = 0;
+             /* 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_resume_breakpoint =
+               set_momentary_breakpoint (sr_sal, (CORE_ADDR)0,
+                                         bp_step_resume);
+             if (breakpoints_inserted)
+               insert_breakpoints ();
 
-         /* We've wandered out of the step range (but haven't done a
-            subroutine call or return).  */
+             /* And make sure stepping stops right away then.  */
+             step_range_end = step_range_start;
+           }
+         goto keep_going;
+       }
 
-         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 */
+      /* We've wandered out of the step range (but haven't done a
+        subroutine call or return).  (Is that true?  I think we get
+        here if we did a return and maybe a longjmp).  */
+
+      sal = find_pc_line(stop_pc, 0);
+
+      if (step_range_end == 1)
+       {
+         /* It is stepi or nexti.  We always want to stop stepping after
+            one instruction.  */
+         stop_step = 1;
+         break;
+       }
+
+      if (sal.line == 0)
+       {
+         /* We have no line number information.  That means to stop
+            stepping (does this always happen right after one instruction,
+            when we do "s" in a function with no line numbers,
+            or can this happen as a result of a return or longjmp?).  */
+         stop_step = 1;
+         break;
+       }
+
+      if (stop_pc == sal.pc && current_line != sal.line)
+       {
+         /* We are at the start of a different line.  So stop.  Note that
+            we don't stop if we step into the middle of a different line.
+            That is said to make things like for (;;) statements work
+            better.  */
+         stop_step = 1;
+         break;
        }
 
+      /* We aren't done stepping.
+
+        Optimize by setting the stepping range to 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 keep_going;
+
+    check_sigtramp2:
       if (trap_expected
          && IN_SIGTRAMP (stop_pc, stop_func_name)
          && !IN_SIGTRAMP (prev_pc, prev_func_name))
@@ -1086,27 +1079,31 @@ step_into_function:
             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);
+            and continue until we hit it, and then step.  FIXME: This should
+            be more enduring than a step_resume breakpoint; we should know
+            that we will later need to keep going rather than re-hitting
+            the breakpoint here (see testsuite/gdb.t06/signals.exp where
+            it says "exceedingly difficult").  */
+         struct symtab_and_line sr_sal;
+
+         sr_sal.pc = prev_pc;
+         sr_sal.symtab = NULL;
+         sr_sal.line = 0;
+         step_resume_breakpoint =
+           set_momentary_breakpoint (sr_sal, get_current_frame (),
+                                     bp_step_resume);
          if (breakpoints_inserted)
-           insert_step_breakpoint ();
+           insert_breakpoints ();
+
          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:
+      /* Come to this label when you need to resume the inferior.
+        It's really much cleaner to do a goto than a maze of if-else
+        conditions.  */
 
-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
@@ -1125,8 +1122,8 @@ save_pc:
          /* 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)
+         resume ((step_range_end && step_resume_breakpoint == NULL)
+                 || (trap_expected && step_resume_breakpoint == NULL)
                  || bpstat_should_step (),
                  stop_signal);
        }
@@ -1145,7 +1142,7 @@ save_pc:
             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 &&
+         if (step_resume_breakpoint == NULL &&
              remove_breakpoints_on_following_step)
            {
              remove_breakpoints_on_following_step = 0;
@@ -1153,9 +1150,8 @@ save_pc:
              breakpoints_inserted = 0;
            }
          else if (!breakpoints_inserted &&
-                  (step_resume_break_address != 0 || !another_trap))
+                  (step_resume_breakpoint != NULL || !another_trap))
            {
-             insert_step_breakpoint ();
              breakpoints_failed = insert_breakpoints ();
              if (breakpoints_failed)
                break;
@@ -1186,7 +1182,7 @@ save_pc:
             }
 #endif /* SHIFT_INST_REGS */
 
-         resume ((!step_resume_break_address
+         resume ((step_resume_breakpoint == NULL
                   && !handling_longjmp
                   && (step_range_end
                       || trap_expected))
@@ -1206,6 +1202,7 @@ save_pc:
       prev_func_name = stop_func_name;
       prev_sp = stop_sp;
     }
+  do_cleanups (old_cleanups);
 }
 \f
 /* Here to return control to GDB when the inferior stops for real.
@@ -1233,9 +1230,6 @@ normal_stop ()
 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 ())
       {
@@ -1268,7 +1262,7 @@ Further execution is probably impossible.\n");
   if (stop_command->hook)
     {
       catch_errors (hook_stop_stub, (char *)stop_command->hook,
-                   "Error while running hook_stop:\n");
+                   "Error while running hook_stop:\n", RETURN_MASK_ALL);
     }
 
   if (!target_has_stack)
@@ -1321,23 +1315,6 @@ hook_stop_stub (cmd)
   execute_user_command ((struct cmd_list_element *)cmd, 0);
   return (0);
 }
-
-\f
-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)
-    target_remove_breakpoint (step_resume_break_address,
-                             step_resume_break_shadow);
-}
 \f
 int signal_stop_state (signo)
      int signo;
@@ -1608,7 +1585,6 @@ save_inferior_status (inf_status, restore_stack_info)
   inf_status->step_range_end = step_range_end;
   inf_status->step_frame_address = step_frame_address;
   inf_status->step_over_calls = step_over_calls;
-  inf_status->step_resume_break_address = step_resume_break_address;
   inf_status->stop_after_trap = stop_after_trap;
   inf_status->stop_soon_quietly = stop_soon_quietly;
   /* Save original bpstat chain here; replace it with copy of chain. 
@@ -1646,7 +1622,6 @@ restore_inferior_status (inf_status)
   step_range_end = inf_status->step_range_end;
   step_frame_address = inf_status->step_frame_address;
   step_over_calls = inf_status->step_over_calls;
-  step_resume_break_address = inf_status->step_resume_break_address;
   stop_after_trap = inf_status->stop_after_trap;
   stop_soon_quietly = inf_status->stop_soon_quietly;
   bpstat_clear (&stop_bpstat);
@@ -1717,7 +1692,7 @@ Pass and Stop may be combined.");
   stop_command = add_cmd ("stop", class_obscure, not_just_help_class_command,
           "There is no `stop' command, but you can set a hook on `stop'.\n\
 This allows you to set a list of commands to be run each time execution\n\
-of the inferior program stops.", &cmdlist);
+of the program stops.", &cmdlist);
 
   numsigs = signo_max () + 1;
   signal_stop    = (unsigned char *)    
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