(attach_deaths): Don't add a REG_DEAD note if a REG_UNUSED note is

already present.

From-SVN: r9871

gcc/sched.c

@@ -2864,7 +2864,12 @@ attach_deaths (x, insn, set_p)
 #endif
 		&& regno != STACK_POINTER_REGNUM)
 	      {
-		if (! all_needed && ! dead_or_set_p (insn, x))
+		/* ??? It is perhaps a dead_or_set_p bug that it does
+		   not check for REG_UNUSED notes itself.  This is necessary
+		   for the case where the SET_DEST is a subreg of regno, as
+		   dead_or_set_p handles subregs specially.  */
+		if (! all_needed && ! dead_or_set_p (insn, x)
+		    && ! find_regno_note (insn, REG_UNUSED, regno))
 		  {
 		    /* Check for the case where the register dying partially
 		       overlaps the register set by this insn.  */