dce.c (delete_unmarked_insns): Just delete the RETVAL and LIBCALL notes if...

2007-10-28  Andreas Krebbel  <krebbel1@de.ibm.com>

	* dce.c (delete_unmarked_insns): Just delete the RETVAL and
	LIBCALL notes if they are about to be moved to the same insn.

From-SVN: r129693

gcc/ChangeLog

+2007-10-28  Andreas Krebbel  <krebbel1@de.ibm.com>
+
+	* dce.c (delete_unmarked_insns): Just delete the RETVAL and
+	LIBCALL notes if they are about to be moved to the same insn.
+
 2007-10-27  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/33870

gcc/dce.c

@@ -346,10 +346,17 @@ delete_unmarked_insns (void)
 	      rtx new_libcall_insn = next_real_insn (insn);
 	      rtx retval_note = find_reg_note (XEXP (note, 0),
 					       REG_RETVAL, NULL_RTX);
-	      REG_NOTES (new_libcall_insn)
-		= gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
-				     REG_NOTES (new_libcall_insn));
-	      XEXP (retval_note, 0) = new_libcall_insn;
+	      /* If the RETVAL and LIBCALL notes would land on the same
+		 insn just remove them.  */
+	      if (XEXP (note, 0) == new_libcall_insn)
+		remove_note (new_libcall_insn, retval_note);
+	      else
+		{
+		  REG_NOTES (new_libcall_insn)
+		    = gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
+					 REG_NOTES (new_libcall_insn));
+		  XEXP (retval_note, 0) = new_libcall_insn;
+		}
 	    }
 
 	  /* If the insn contains a REG_RETVAL note and is dead, but the