Re: Fix to debugging problem on Alpha

[Richard Henderson <rth at cygnus dot com>]

On Mon, May 22, 2000 at 07:09:05PM -0700, Richard Henderson wrote:
> Namely, in thread_prologue_epilogue_insns, after emitting the
> prologue, move all of the line number notes after the prologue.

Like so.

I'll leave it to you to revert your patch.  If you don't do so,
please fix alpha_align_insns, which is broken by your change.


r~


        * function.c (thread_prologue_and_epilogue_insns): Make sure 
        existing line number notes appear after the prologue.

Index: function.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/function.c,v
retrieving revision 1.197
retrieving revision 1.198
diff -c -p -d -r1.197 -r1.198
*** function.c	2000/05/17 08:15:25	1.197
--- function.c	2000/05/23 03:40:53	1.198
*************** void
*** 6812,6826 ****
  thread_prologue_and_epilogue_insns (f)
       rtx f ATTRIBUTE_UNUSED;
  {
!   int insertted = 0;
    edge e;
    rtx seq;
  
  #ifdef HAVE_prologue
    if (HAVE_prologue)
      {
-       rtx insn;
- 
        start_sequence ();
        seq = gen_prologue();
        emit_insn (seq);
--- 6812,6827 ----
  thread_prologue_and_epilogue_insns (f)
       rtx f ATTRIBUTE_UNUSED;
  {
!   int inserted = 0;
    edge e;
    rtx seq;
+ #ifdef HAVE_prologue
+   rtx prologue_end = NULL_RTX;
+ #endif
  
  #ifdef HAVE_prologue
    if (HAVE_prologue)
      {
        start_sequence ();
        seq = gen_prologue();
        emit_insn (seq);
*************** thread_prologue_and_epilogue_insns (f)
*** 6829,6854 ****
        if (GET_CODE (seq) != SEQUENCE)
  	seq = get_insns ();
        record_insns (seq, &prologue);
!       emit_note (NULL, NOTE_INSN_PROLOGUE_END);
! 
!       /* GDB handles `break f' by setting a breakpoint on the first
! 	 line note *after* the prologue.  That means that we should
! 	 insert a line note here; otherwise, if the next line note
! 	 comes part way into the next block, GDB will skip all the way
! 	 to that point.  */
!       insn = next_nonnote_insn (f);
!       while (insn)
! 	{
! 	  if (GET_CODE (insn) == NOTE 
! 	      && NOTE_LINE_NUMBER (insn) >= 0)
! 	    {
! 	      emit_line_note_force (NOTE_SOURCE_FILE (insn),
! 				    NOTE_LINE_NUMBER (insn));
! 	      break;
! 	    }
! 
! 	  insn = PREV_INSN (insn);
! 	}
  
        seq = gen_sequence ();
        end_sequence ();
--- 6830,6836 ----
        if (GET_CODE (seq) != SEQUENCE)
  	seq = get_insns ();
        record_insns (seq, &prologue);
!       prologue_end = emit_note (NULL, NOTE_INSN_PROLOGUE_END);
  
        seq = gen_sequence ();
        end_sequence ();
*************** thread_prologue_and_epilogue_insns (f)
*** 6862,6868 ****
  	    abort ();
  
  	  insert_insn_on_edge (seq, ENTRY_BLOCK_PTR->succ);
! 	  insertted = 1;
  	}
        else
  	emit_insn_after (seq, f);
--- 6844,6850 ----
  	    abort ();
  
  	  insert_insn_on_edge (seq, ENTRY_BLOCK_PTR->succ);
! 	  inserted = 1;
  	}
        else
  	emit_insn_after (seq, f);
*************** thread_prologue_and_epilogue_insns (f)
*** 6977,6983 ****
  	  seq = gen_sequence ();
  	  end_sequence ();
  	  insert_insn_on_edge (seq, e);
! 	  insertted = 1;
  	}
        goto epilogue_done;
      }
--- 6959,6965 ----
  	  seq = gen_sequence ();
  	  end_sequence ();
  	  insert_insn_on_edge (seq, e);
! 	  inserted = 1;
  	}
        goto epilogue_done;
      }
*************** thread_prologue_and_epilogue_insns (f)
*** 7011,7022 ****
        end_sequence();
  
        insert_insn_on_edge (seq, e);
!       insertted = 1;
      }
  #endif
  epilogue_done:
  
!   if (insertted)
      commit_edge_insertions ();
  
  #ifdef HAVE_sibcall_epilogue
--- 6993,7004 ----
        end_sequence();
  
        insert_insn_on_edge (seq, e);
!       inserted = 1;
      }
  #endif
  epilogue_done:
  
!   if (inserted)
      commit_edge_insertions ();
  
  #ifdef HAVE_sibcall_epilogue
*************** epilogue_done:
*** 7047,7052 ****
--- 7029,7082 ----
  	 avoid getting rid of sibcall epilogue insns.  */
        record_insns (GET_CODE (seq) == SEQUENCE
  		    ? seq : newinsn, &sibcall_epilogue);
+     }
+ #endif
+ 
+ #ifdef HAVE_prologue
+   if (prologue_end)
+     {
+       rtx insn, prev;
+ 
+       /* GDB handles `break f' by setting a breakpoint on the first
+ 	 line note *after* the prologue.  Which means (1) that if
+ 	 there are line number notes before where we inserted the
+ 	 prologue we should move them, and (2) if there is no such
+ 	 note, then we should generate one at the prologue.  */
+ 
+       for (insn = prologue_end; insn ; insn = prev)
+ 	{
+ 	  prev = PREV_INSN (insn);
+ 	  if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) > 0)
+ 	    {
+ 	      /* Note that we cannot reorder the first insn in the
+ 		 chain, since rest_of_compilation relies on that
+ 		 remaining constant.  Do the next best thing.  */
+ 	      if (prev == NULL)
+ 		{
+ 		  emit_line_note_after (NOTE_SOURCE_FILE (insn),
+ 					NOTE_LINE_NUMBER (insn),
+ 					prologue_end);
+ 		  NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
+ 		}
+ 	      else
+ 		reorder_insns (insn, insn, prologue_end);
+ 	    }
+ 	}
+ 
+       insn = NEXT_INSN (prologue_end);
+       if (! insn || GET_CODE (insn) != NOTE || NOTE_LINE_NUMBER (insn) <= 0)
+ 	{
+ 	  for (insn = next_active_insn (f); insn ; insn = PREV_INSN (insn))
+ 	    {
+ 	      if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) > 0)
+ 		{
+ 		  emit_line_note_after (NOTE_SOURCE_FILE (insn),
+ 					NOTE_LINE_NUMBER (insn),
+ 					prologue_end);
+ 		  break;
+ 		}
+ 	    }
+ 	}
      }
  #endif
  }