(record_giv): When computing replaceable, use

back_branch_in_range_p instead of looking for branches to named
labels.

From-SVN: r9675

diff --git a/gcc/loop.c b/gcc/loop.c
index f6fc598d8d1c4850d37dce6577e404b656a7d2fb..f67d6535231a165d88736908fc79bb5181160ba6 100644 (file)
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -4418,46 +4418,16 @@ record_giv (v, insn, src_reg, dest_reg, mult_val, add_val, benefit,
                }
            }
 
-         /* Check each insn between the first and last use of the giv,
-            and fail if any of them are branches that jump to a named label
-            outside this range, but still inside the loop.  This catches
-            cases of spaghetti code where the execution order of insns
-            is not linear, and hence the above test fails.  For example,
-            in the following code, j is not replaceable:
-            for (i = 0; i < 100; )      {
-            L0:        j = 4*i; goto L1;
-            L2:        k = j;   goto L3;
-            L1:        i++;     goto L2;
-            L3:        ;        }
-            printf ("k = %d\n", k); }
-            This test is conservative, but this test succeeds rarely enough
-            that it isn't a problem.  See also check_final_value below.  */
-
+         /* If there are any backwards branches that go from after the
+            biv update to before it, then this giv is not replaceable.  */
          if (v->replaceable)
-           for (p = insn;
-                INSN_UID (p) >= max_uid_for_loop
-                || INSN_LUID (p) < uid_luid[regno_last_uid[REGNO (dest_reg)]];
-                p = NEXT_INSN (p))
-             {
-               if (GET_CODE (p) == JUMP_INSN && JUMP_LABEL (p)
-                   && LABEL_NAME (JUMP_LABEL (p))
-                   && ((INSN_LUID (JUMP_LABEL (p)) > INSN_LUID (loop_start)
-                        && (INSN_LUID (JUMP_LABEL (p))
-                            < uid_luid[regno_first_uid[REGNO (dest_reg)]]))
-                       || (INSN_LUID (JUMP_LABEL (p)) < INSN_LUID (loop_end)
-                           && (INSN_LUID (JUMP_LABEL (p))
-                               > uid_luid[regno_last_uid[REGNO (dest_reg)]]))))
-                 {
-                   v->replaceable = 0;
-                   v->not_replaceable = 1;
-
-                   if (loop_dump_stream)
-                     fprintf (loop_dump_stream,
-                              "Found branch outside giv lifetime.\n");
-
-                   break;
-                 }
-             }
+           for (b = bl->biv; b; b = b->next_iv)
+             if (back_branch_in_range_p (b->insn, loop_start, loop_end))
+               {
+                 v->replaceable = 0;
+                 v->not_replaceable = 1;
+                 break;
+               }
        }
       else
        {