/* Perform instruction reorganizations for delay slot filling.
- Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+ 2001, 2002, 2003, 2004, 2005, 2006, 2007
+ Free Software Foundation, Inc.
Contributed by Richard Kenner (kenner@vlsi1.ultra.nyu.edu).
Hacked by Michael Tiemann (tiemann@cygnus.com).
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
-Software Foundation; either version 2, or (at your option) any later
+Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
/* Instruction reorganization pass.
static void fix_reg_dead_note (rtx, rtx);
static void update_reg_unused_notes (rtx, rtx);
static void fill_simple_delay_slots (int);
-static rtx fill_slots_from_thread (rtx, rtx, rtx, rtx, int, int, int, int,
+static rtx fill_slots_from_thread (rtx, rtx, rtx, rtx,
+ int, int, int, int,
int *, rtx);
static void fill_eager_delay_slots (void);
static void relax_delay_slots (rtx);
for (li = list; li; li = XEXP (li, 1), i++)
{
- rtx tem = copy_rtx (XEXP (li, 0));
+ rtx tem = XEXP (li, 0);
rtx note, next;
/* Show that this copy of the insn isn't deleted. */
remove_note (tem, note);
break;
- case REG_LABEL:
+ case REG_LABEL_OPERAND:
+ case REG_LABEL_TARGET:
/* Keep the label reference count up to date. */
if (LABEL_P (XEXP (note, 0)))
LABEL_NUSES (XEXP (note, 0)) ++;
prev = PREV_INSN (seq_insn);
trial = XVECEXP (seq, 0, 0);
delete_related_insns (seq_insn);
- add_insn_after (trial, prev);
+ add_insn_after (trial, prev, NULL);
/* If there was a barrier after the old SEQUENCE, remit it. */
if (had_barrier)
}
}
\f
+/* Return the label before INSN, or put a new label there. */
+
+static rtx
+get_label_before (rtx insn)
+{
+ rtx label;
+
+ /* Find an existing label at this point
+ or make a new one if there is none. */
+ label = prev_nonnote_insn (insn);
+
+ if (label == 0 || !LABEL_P (label))
+ {
+ rtx prev = PREV_INSN (insn);
+
+ label = gen_label_rtx ();
+ emit_label_after (label, prev);
+ LABEL_NUSES (label) = 0;
+ }
+ return label;
+}
+
/* Scan a function looking for insns that need a delay slot and find insns to
put into the delay slot.
#endif
}
\f
+/* Follow any unconditional jump at LABEL;
+ return the ultimate label reached by any such chain of jumps.
+ Return null if the chain ultimately leads to a return instruction.
+ If LABEL is not followed by a jump, return LABEL.
+ If the chain loops or we can't find end, return LABEL,
+ since that tells caller to avoid changing the insn. */
+
+static rtx
+follow_jumps (rtx label)
+{
+ rtx insn;
+ rtx next;
+ rtx value = label;
+ int depth;
+
+ for (depth = 0;
+ (depth < 10
+ && (insn = next_active_insn (value)) != 0
+ && JUMP_P (insn)
+ && ((JUMP_LABEL (insn) != 0 && any_uncondjump_p (insn)
+ && onlyjump_p (insn))
+ || GET_CODE (PATTERN (insn)) == RETURN)
+ && (next = NEXT_INSN (insn))
+ && BARRIER_P (next));
+ depth++)
+ {
+ rtx tem;
+
+ /* If we have found a cycle, make the insn jump to itself. */
+ if (JUMP_LABEL (insn) == label)
+ return label;
+
+ tem = next_active_insn (JUMP_LABEL (insn));
+ if (tem && (GET_CODE (PATTERN (tem)) == ADDR_VEC
+ || GET_CODE (PATTERN (tem)) == ADDR_DIFF_VEC))
+ break;
+
+ value = JUMP_LABEL (insn);
+ }
+ if (depth == 10)
+ return label;
+ return value;
+}
+
/* Try to find insns to place in delay slots.
INSN is the jump needing SLOTS_TO_FILL delay slots. It tests CONDITION
/* We are moving this insn, not deleting it. We must
temporarily increment the use count on any referenced
label lest it be deleted by delete_related_insns. */
- note = find_reg_note (trial, REG_LABEL, 0);
- /* REG_LABEL could be NOTE_INSN_DELETED_LABEL too. */
- if (note && LABEL_P (XEXP (note, 0)))
+ for (note = REG_NOTES (trial);
+ note != NULL;
+ note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_LABEL_OPERAND
+ || REG_NOTE_KIND (note) == REG_LABEL_TARGET)
+ {
+ /* REG_LABEL_OPERAND could be
+ NOTE_INSN_DELETED_LABEL too. */
+ if (LABEL_P (XEXP (note, 0)))
+ LABEL_NUSES (XEXP (note, 0))++;
+ else
+ gcc_assert (REG_NOTE_KIND (note)
+ == REG_LABEL_OPERAND);
+ }
+ if (JUMP_P (trial) && JUMP_LABEL (trial))
LABEL_NUSES (XEXP (note, 0))++;
delete_related_insns (trial);
- if (note && LABEL_P (XEXP (note, 0)))
+ for (note = REG_NOTES (trial);
+ note != NULL;
+ note = XEXP (note, 1))
+ if (REG_NOTE_KIND (note) == REG_LABEL_OPERAND
+ || REG_NOTE_KIND (note) == REG_LABEL_TARGET)
+ {
+ /* REG_LABEL_OPERAND could be
+ NOTE_INSN_DELETED_LABEL too. */
+ if (LABEL_P (XEXP (note, 0)))
+ LABEL_NUSES (XEXP (note, 0))--;
+ else
+ gcc_assert (REG_NOTE_KIND (note)
+ == REG_LABEL_OPERAND);
+ }
+ if (JUMP_P (trial) && JUMP_LABEL (trial))
LABEL_NUSES (XEXP (note, 0))--;
}
else
}
}
\f
+static void delete_computation (rtx insn);
+
+/* Recursively delete prior insns that compute the value (used only by INSN
+ which the caller is deleting) stored in the register mentioned by NOTE
+ which is a REG_DEAD note associated with INSN. */
+
+static void
+delete_prior_computation (rtx note, rtx insn)
+{
+ rtx our_prev;
+ rtx reg = XEXP (note, 0);
+
+ for (our_prev = prev_nonnote_insn (insn);
+ our_prev && (NONJUMP_INSN_P (our_prev)
+ || CALL_P (our_prev));
+ our_prev = prev_nonnote_insn (our_prev))
+ {
+ rtx pat = PATTERN (our_prev);
+
+ /* If we reach a CALL which is not calling a const function
+ or the callee pops the arguments, then give up. */
+ if (CALL_P (our_prev)
+ && (! CONST_OR_PURE_CALL_P (our_prev)
+ || GET_CODE (pat) != SET || GET_CODE (SET_SRC (pat)) != CALL))
+ break;
+
+ /* If we reach a SEQUENCE, it is too complex to try to
+ do anything with it, so give up. We can be run during
+ and after reorg, so SEQUENCE rtl can legitimately show
+ up here. */
+ if (GET_CODE (pat) == SEQUENCE)
+ break;
+
+ if (GET_CODE (pat) == USE
+ && NONJUMP_INSN_P (XEXP (pat, 0)))
+ /* reorg creates USEs that look like this. We leave them
+ alone because reorg needs them for its own purposes. */
+ break;
+
+ if (reg_set_p (reg, pat))
+ {
+ if (side_effects_p (pat) && !CALL_P (our_prev))
+ break;
+
+ if (GET_CODE (pat) == PARALLEL)
+ {
+ /* If we find a SET of something else, we can't
+ delete the insn. */
+
+ int i;
+
+ for (i = 0; i < XVECLEN (pat, 0); i++)
+ {
+ rtx part = XVECEXP (pat, 0, i);
+
+ if (GET_CODE (part) == SET
+ && SET_DEST (part) != reg)
+ break;
+ }
+
+ if (i == XVECLEN (pat, 0))
+ delete_computation (our_prev);
+ }
+ else if (GET_CODE (pat) == SET
+ && REG_P (SET_DEST (pat)))
+ {
+ int dest_regno = REGNO (SET_DEST (pat));
+ int dest_endregno = END_REGNO (SET_DEST (pat));
+ int regno = REGNO (reg);
+ int endregno = END_REGNO (reg);
+
+ if (dest_regno >= regno
+ && dest_endregno <= endregno)
+ delete_computation (our_prev);
+
+ /* We may have a multi-word hard register and some, but not
+ all, of the words of the register are needed in subsequent
+ insns. Write REG_UNUSED notes for those parts that were not
+ needed. */
+ else if (dest_regno <= regno
+ && dest_endregno >= endregno)
+ {
+ int i;
+
+ REG_NOTES (our_prev)
+ = gen_rtx_EXPR_LIST (REG_UNUSED, reg,
+ REG_NOTES (our_prev));
+
+ for (i = dest_regno; i < dest_endregno; i++)
+ if (! find_regno_note (our_prev, REG_UNUSED, i))
+ break;
+
+ if (i == dest_endregno)
+ delete_computation (our_prev);
+ }
+ }
+
+ break;
+ }
+
+ /* If PAT references the register that dies here, it is an
+ additional use. Hence any prior SET isn't dead. However, this
+ insn becomes the new place for the REG_DEAD note. */
+ if (reg_overlap_mentioned_p (reg, pat))
+ {
+ XEXP (note, 1) = REG_NOTES (our_prev);
+ REG_NOTES (our_prev) = note;
+ break;
+ }
+ }
+}
+
+/* Delete INSN and recursively delete insns that compute values used only
+ by INSN. This uses the REG_DEAD notes computed during flow analysis.
+ If we are running before flow.c, we need do nothing since flow.c will
+ delete dead code. We also can't know if the registers being used are
+ dead or not at this point.
+
+ Otherwise, look at all our REG_DEAD notes. If a previous insn does
+ nothing other than set a register that dies in this insn, we can delete
+ that insn as well.
+
+ On machines with CC0, if CC0 is used in this insn, we may be able to
+ delete the insn that set it. */
+
+static void
+delete_computation (rtx insn)
+{
+ rtx note, next;
+
+#ifdef HAVE_cc0
+ if (reg_referenced_p (cc0_rtx, PATTERN (insn)))
+ {
+ rtx prev = prev_nonnote_insn (insn);
+ /* We assume that at this stage
+ CC's are always set explicitly
+ and always immediately before the jump that
+ will use them. So if the previous insn
+ exists to set the CC's, delete it
+ (unless it performs auto-increments, etc.). */
+ if (prev && NONJUMP_INSN_P (prev)
+ && sets_cc0_p (PATTERN (prev)))
+ {
+ if (sets_cc0_p (PATTERN (prev)) > 0
+ && ! side_effects_p (PATTERN (prev)))
+ delete_computation (prev);
+ else
+ /* Otherwise, show that cc0 won't be used. */
+ REG_NOTES (prev) = gen_rtx_EXPR_LIST (REG_UNUSED,
+ cc0_rtx, REG_NOTES (prev));
+ }
+ }
+#endif
+
+ for (note = REG_NOTES (insn); note; note = next)
+ {
+ next = XEXP (note, 1);
+
+ if (REG_NOTE_KIND (note) != REG_DEAD
+ /* Verify that the REG_NOTE is legitimate. */
+ || !REG_P (XEXP (note, 0)))
+ continue;
+
+ delete_prior_computation (note, insn);
+ }
+
+ delete_related_insns (insn);
+}
+
+/* If all INSN does is set the pc, delete it,
+ and delete the insn that set the condition codes for it
+ if that's what the previous thing was. */
+
+static void
+delete_jump (rtx insn)
+{
+ rtx set = single_set (insn);
+
+ if (set && GET_CODE (SET_DEST (set)) == PC)
+ delete_computation (insn);
+}
+
+\f
/* Once we have tried two ways to fill a delay slot, make a pass over the
code to try to improve the results and to do such things as more jump
threading. */
for (i = 0; i < XVECLEN (pat, 0); i++)
{
rtx this_insn = XVECEXP (pat, 0, i);
- add_insn_after (this_insn, after);
+ add_insn_after (this_insn, after, NULL);
after = this_insn;
}
delete_scheduled_jump (delay_insn);
for (i = 0; i < XVECLEN (pat, 0); i++)
{
rtx this_insn = XVECEXP (pat, 0, i);
- add_insn_after (this_insn, after);
+ add_insn_after (this_insn, after, NULL);
after = this_insn;
}
delete_scheduled_jump (delay_insn);
if (INSN_UID (insn) > max_uid)
max_uid = INSN_UID (insn);
if (NOTE_P (insn)
- && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EPILOGUE_BEG)
+ && NOTE_KIND (insn) == NOTE_INSN_EPILOGUE_BEG)
epilogue_insn = insn;
}
relax_delay_slots (first);
}
- /* Delete any USE insns made by update_block; subsequent passes don't need
- them or know how to deal with them. */
- for (insn = first; insn; insn = next)
- {
- next = NEXT_INSN (insn);
-
- if (NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == USE
- && INSN_P (XEXP (PATTERN (insn), 0)))
- next = delete_related_insns (insn);
- }
-
/* If we made an end of function label, indicate that it is now
safe to delete it by undoing our prior adjustment to LABEL_NUSES.
If it is now unused, delete it. */
make_return_insns (first);
#endif
+ /* Delete any USE insns made by update_block; subsequent passes don't need
+ them or know how to deal with them. */
+ for (insn = first; insn; insn = next)
+ {
+ next = NEXT_INSN (insn);
+
+ if (NONJUMP_INSN_P (insn) && GET_CODE (PATTERN (insn)) == USE
+ && INSN_P (XEXP (PATTERN (insn), 0)))
+ next = delete_related_insns (insn);
+ }
+
obstack_free (&unfilled_slots_obstack, unfilled_firstobj);
/* It is not clear why the line below is needed, but it does seem to be. */
link = XEXP (link, 1))
INSN_LOCATOR (XEXP (link, 0)) = 0;
}
+
#endif
}
#endif /* DELAY_SLOTS */
{
#ifdef DELAY_SLOTS
return flag_delayed_branch;
-#else
+#else
return 0;
#endif
}
dbr_schedule (get_insns ());
#endif
return 0;
-}
+}
struct tree_opt_pass pass_delay_slots =
{
TODO_ggc_collect, /* todo_flags_finish */
'M' /* letter */
};
-
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