Re: [Committed] S/390: PR57609 fix - use next_active_insn instead of next_real_insn

[Steven Bosscher <stevenb dot gcc at gmail dot com>]

On Tue, Jun 18, 2013 at 2:17 PM, Andreas Krebbel wrote:
> If you don't want me to use next_active_insn I probably have to do
> something like this instead:

No. If the label is followed by jump table data, then NEXT_INSN(label)
will be the JUMP_TABLE_DATA rtx. See tablejump_p.

So the following should work:

Index: s390.c
===================================================================
--- s390.c      (revision 200173)
+++ s390.c      (working copy)
@@ -7023,7 +7023,7 @@ s390_chunkify_start (void)
       if (LABEL_P (insn)
          && (LABEL_PRESERVE_P (insn) || LABEL_NAME (insn)))
        {
-         rtx vec_insn = next_active_insn (insn);
+         rtx vec_insn = NEXT_INSN (insn);
          if (! vec_insn || ! JUMP_TABLE_DATA_P (vec_insn))
            bitmap_set_bit (far_labels, CODE_LABEL_NUMBER (insn));
        }
@@ -7054,7 +7054,7 @@ s390_chunkify_start (void)
            {
              /* Find the jump table used by this casesi jump.  */
              rtx vec_label = XEXP (XEXP (XVECEXP (pat, 0, 1), 0), 0);
-             rtx vec_insn = next_active_insn (vec_label);
+             rtx vec_insn = NEXT_INSN (vec_label);
              if (vec_insn && JUMP_TABLE_DATA_P (vec_insn))
                {
                  rtx vec_pat = PATTERN (vec_insn);


BTW I don't understand how a label satisfying the following can be
true for a label before a jump table:

      if (LABEL_P (insn)
          && (LABEL_PRESERVE_P (insn) || LABEL_NAME (insn)))

LABEL_PRESERVE_P should never be set on a label before a
JUMP_TABLE_DATA, and LABEL_NAME should be NULL.

Better yet would be to use tablejump_p instead of examining the
pattern by hand, e.g.:

Index: s390.c
===================================================================
--- s390.c      (revision 200173)
+++ s390.c      (working copy)
@@ -7023,7 +7023,7 @@ s390_chunkify_start (void)
       if (LABEL_P (insn)
          && (LABEL_PRESERVE_P (insn) || LABEL_NAME (insn)))
        {
-         rtx vec_insn = next_active_insn (insn);
+         rtx vec_insn = NEXT_INSN (insn);
          if (! vec_insn || ! JUMP_TABLE_DATA_P (vec_insn))
            bitmap_set_bit (far_labels, CODE_LABEL_NUMBER (insn));
        }
@@ -7033,6 +7033,8 @@ s390_chunkify_start (void)
       else if (JUMP_P (insn))
        {
           rtx pat = PATTERN (insn);
+          rtx table;
+
          if (GET_CODE (pat) == PARALLEL && XVECLEN (pat, 0) > 2)
            pat = XVECEXP (pat, 0, 0);

@@ -7046,28 +7048,18 @@ s390_chunkify_start (void)
                    bitmap_set_bit (far_labels, CODE_LABEL_NUMBER (label));
                }
             }
-         else if (GET_CODE (pat) == PARALLEL
-                  && XVECLEN (pat, 0) == 2
-                  && GET_CODE (XVECEXP (pat, 0, 0)) == SET
-                  && GET_CODE (XVECEXP (pat, 0, 1)) == USE
-                  && GET_CODE (XEXP (XVECEXP (pat, 0, 1), 0)) == LABEL_REF)
-           {
-             /* Find the jump table used by this casesi jump.  */
-             rtx vec_label = XEXP (XEXP (XVECEXP (pat, 0, 1), 0), 0);
-             rtx vec_insn = next_active_insn (vec_label);
-             if (vec_insn && JUMP_TABLE_DATA_P (vec_insn))
-               {
-                 rtx vec_pat = PATTERN (vec_insn);
-                 int i, diff_p = GET_CODE (vec_pat) == ADDR_DIFF_VEC;
-
-                 for (i = 0; i < XVECLEN (vec_pat, diff_p); i++)
-                   {
-                     rtx label = XEXP (XVECEXP (vec_pat, diff_p, i), 0);
-
-                     if (s390_find_pool (pool_list, label)
-                         != s390_find_pool (pool_list, insn))
-                       bitmap_set_bit (far_labels, CODE_LABEL_NUMBER (label));
-                   }
+         else if (tablejump_p (insn, NULL, &table))
+           {
+             rtx vec_pat = PATTERN (table);
+             int i, diff_p = GET_CODE (vec_pat) == ADDR_DIFF_VEC;
+
+             for (i = 0; i < XVECLEN (vec_pat, diff_p); i++)
+               {
+                 rtx label = XEXP (XVECEXP (vec_pat, diff_p, i), 0);
+
+                 if (s390_find_pool (pool_list, label)
+                     != s390_find_pool (pool_list, insn))
+                   bitmap_set_bit (far_labels, CODE_LABEL_NUMBER (label));
                }
            }
         }

Ciao!
Steven