PR c++/15815

[pf3gnuchains/gcc-fork.git] / gcc / loop.c

diff --git a/gcc/loop.c b/gcc/loop.c
index 17955b4..e0af19d 100644 (file)
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -8284,6 +8284,7 @@ check_dbra_loop (struct loop *loop, int insn_count)
              enum rtx_code cmp_code;
              int comparison_const_width;
              unsigned HOST_WIDE_INT comparison_sign_mask;
+             bool keep_first_compare;
 
              add_val = INTVAL (bl->biv->add_val);
              comparison_value = XEXP (comparison, 1);
@@ -8476,13 +8477,26 @@ check_dbra_loop (struct loop *loop, int insn_count)
                 not delete the label.  */
              LABEL_NUSES (XEXP (jump_label, 0))++;
 
+             /* If we have a separate comparison insn that does more
+                than just set cc0, the result of the comparison might
+                be used outside the loop.  */
+             keep_first_compare = (compare_and_branch == 2
+#ifdef HAVE_CC0
+                                   && sets_cc0_p (first_compare) <= 0
+#endif
+                                   );
+
              /* Emit an insn after the end of the loop to set the biv's
                 proper exit value if it is used anywhere outside the loop.  */
-             if ((REGNO_LAST_UID (bl->regno) != INSN_UID (first_compare))
+             if (keep_first_compare
+                 || (REGNO_LAST_UID (bl->regno) != INSN_UID (first_compare))
                  || ! bl->init_insn
                  || REGNO_FIRST_UID (bl->regno) != INSN_UID (bl->init_insn))
                loop_insn_sink (loop, gen_load_of_final_value (reg, final_value));
 
+             if (keep_first_compare)
+               loop_insn_sink (loop, PATTERN (first_compare));
+
              /* Delete compare/branch at end of loop.  */
              delete_related_insns (PREV_INSN (loop_end));
              if (compare_and_branch == 2)