regmove.c (fixup_match_1): Don't move INSN in front of P if it would end up in…

regmove.c (fixup_match_1): Don't move INSN in front of P if it would end up in the shadow of a live flags...

        * regmove.c (fixup_match_1): Don't move INSN in front of P if
        it would end up in the shadow of a live flags regsiter.

From-SVN: r29034

gcc/regmove.c

@@ -1737,6 +1737,13 @@ fixup_match_1 (insn, set, src, src_subreg, dst, backward, operand_number,
       if ((dst_note = find_regno_note (p, REG_DEAD, REGNO (dst)))
 	  && (GET_MODE (XEXP (dst_note, 0)) == GET_MODE (dst)))
 	{
+	  /* If we would be moving INSN, check that we won't move it
+	     into the shadow of a live a live flags register.  */
+	  /* ??? We only try to move it in front of P, although
+		 we could move it anywhere between OVERLAP and P.  */
+	  if (overlap && GET_MODE (PREV_INSN (p)) != VOIDmode)
+	    break;
+
 	  if (! src_note)
 	    {
 	      rtx q;
@@ -1844,8 +1851,11 @@ fixup_match_1 (insn, set, src, src_subreg, dst, backward, operand_number,
 	break;
       if (! src_note && reg_overlap_mentioned_p (src, PATTERN (p)))
 	{
-	  /* INSN was already checked to be movable when
-	     we found no REG_DEAD note for src on it.  */
+	  /* INSN was already checked to be movable wrt. the registers that it
+	     sets / uses when we found no REG_DEAD note for src on it, but it
+	     still might clobber the flags register.  We'll have to check that
+	     we won't insert it into the shadow of a live flags register when
+	     we finally know where we are to move it.  */
 	  overlap = p;
 	  src_note = find_reg_note (p, REG_DEAD, src);
 	}