PATCH: Fix PR2893

[Mark Mitchell <mark at codesourcery dot com>]

I created a new problem in mark_jump_label when I tried to fix it
recently.

This patch fixes the disappearing label that Kaveh experienced on
Solaris 2.7.

Applied as an obvious fix on the mainline and the branch, but with
full testing taking place as we speak.

--
Mark Mitchell                   mark@codesourcery.com
CodeSourcery, LLC               http://www.codesourcery.com

2001-05-23  Mark Mitchell  <mark@codesourcery.com>

	* jump.c (mark_jump_label): Fix thinko in 2001-05-19 change.

Index: jump.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/jump.c,v
retrieving revision 1.153.2.9
diff -c -p -r1.153.2.9 jump.c
*** jump.c	2001/05/19 23:54:58	1.153.2.9
--- jump.c	2001/05/23 07:37:24
*************** mark_jump_label (x, insn, cross_jump, in
*** 2617,2663 ****
  	  {
  	    if (GET_CODE (insn) == JUMP_INSN)
  	      JUMP_LABEL (insn) = label;
! 
! 	    /* If we've changed the label, update notes accordingly.  */
! 	    else if (label != olabel)
  	      {
! 		rtx note;
! 
! 		/* We may have a REG_LABEL note to indicate that this
! 		   instruction uses the label.  */
! 		note = find_reg_note (insn, REG_LABEL, olabel);
! 		if (note)
! 		  XEXP (note, 0) = label;
! 
! 		/* We may also have a REG_EQUAL note to indicate that
! 		   a register is being set to the address of the
! 		   label.  */
! 		note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
! 		if (note 
! 		    && GET_CODE (XEXP (note, 0)) == LABEL_REF
! 		    && XEXP (XEXP (note, 0), 0) == olabel)
! 		  XEXP (XEXP (note, 0), 0) = label;
! 	      }
! 
! 	    /* Otherwise, add a REG_LABEL note for LABEL unless there already
! 	       is one.  */
! 	    else if (! find_reg_note (insn, REG_LABEL, label))
! 	      {
! 		/* This code used to ignore labels which refered to dispatch
! 		   tables to avoid flow.c generating worse code.
! 
! 		   However, in the presense of global optimizations like
! 		   gcse which call find_basic_blocks without calling
! 		   life_analysis, not recording such labels will lead
! 		   to compiler aborts because of inconsistencies in the
! 		   flow graph.  So we go ahead and record the label.
! 
! 		   It may also be the case that the optimization argument
! 		   is no longer valid because of the more accurate cfg
! 		   we build in find_basic_blocks -- it no longer pessimizes
! 		   code when it finds a REG_LABEL note.  */
! 		REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
! 						      REG_NOTES (insn));
  	      }
  	  }
  	return;
--- 2617,2652 ----
  	  {
  	    if (GET_CODE (insn) == JUMP_INSN)
  	      JUMP_LABEL (insn) = label;
! 	    else
  	      {
! 		/* If we've changed the label, update notes accordingly.  */
! 		if (label != olabel)
! 		  {
! 		    rtx note;
! 
! 		    /* We may have a REG_LABEL note to indicate that this
! 		       instruction uses the label.  */
! 		    note = find_reg_note (insn, REG_LABEL, olabel);
! 		    if (note)
! 		      XEXP (note, 0) = label;
! 
! 		    /* We may also have a REG_EQUAL note to indicate that
! 		       a register is being set to the address of the
! 		       label.  */
! 		    note = find_reg_note (insn, REG_EQUAL, NULL_RTX);
! 		    if (note 
! 			&& GET_CODE (XEXP (note, 0)) == LABEL_REF
! 			&& XEXP (XEXP (note, 0), 0) == olabel)
! 		      XEXP (XEXP (note, 0), 0) = label;
! 		  }
! 
! 		/* Add a REG_LABEL note for LABEL unless there already
! 		   is one.  All uses of a label, except for labels
! 		   that are the targets of jumps, must have a
! 		   REG_LABEL note.  */
! 		if (! find_reg_note (insn, REG_LABEL, label))
! 		  REG_NOTES (insn) = gen_rtx_INSN_LIST (REG_LABEL, label,
! 							REG_NOTES (insn));
  	      }
  	  }
  	return;