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Commit b9185691 by Eric Botcazou Committed by Eric Botcazou
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re PR bootstrap/16326 (Bootstrap failure after "RTL prologue/epilogue for SPARC" patch) 

	PR bootstrap/16326
	* reorg.c: Revert 2004-06-30 change.
	(find_end_label): If HAVE_epilogue and !HAVE_return,
	return 0 instead of creating a label at the end of the insn chain.
	(optimize_skip): Account for the failure mode of find_end_label.
	(fill_simple_delay_slots): Likewise.
	(fill_slots_from_thread): Likewise.
	(relax_delay_slots): Likewise.

From-SVN: r84273
parent a6d02559
Showing with 96 additions and 62 deletions
gcc/ChangeLog
2004-07-08 Eric Botcazou <ebotcazou@libertysurf.fr>
PR bootstrap/16326
* reorg.c: Revert 2004-06-30 change.
(find_end_label): If HAVE_epilogue and !HAVE_return,
return 0 instead of creating a label at the end of the insn chain.
(optimize_skip): Account for the failure mode of find_end_label.
(fill_simple_delay_slots): Likewise.
(fill_slots_from_thread): Likewise.
(relax_delay_slots): Likewise.
2004-07-08 Diego Novillo <dnovillo@redhat.com>
* tree-flow.h (addressable_vars): Declare.
......
gcc/reorg.c
......@@ -317,23 +317,25 @@ insn_sets_resource_p (rtx insn, struct resources *res,
mark_set_resources (insn, &insn_sets, 0, include_delayed_effects);
return resource_conflicts_p (&insn_sets, res);
}
/* Return TRUE if INSN is a return, possibly with a filled delay slot. */
static bool
return_insn_p (rtx insn)
{
if (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == RETURN)
return true;
if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE)
return return_insn_p (XVECEXP (PATTERN (insn), 0, 0));
return false;
}
/* Find a label at the end of the function or before a RETURN. If there is
none, make one. */
/* Find a label at the end of the function or before a RETURN. If there
is none, try to make one. If that fails, returns 0.
The property of such a label is that it is placed just before the
epilogue or a bare RETURN insn, so that another bare RETURN can be
turned into a jump to the label unconditionally. In particular, the
label cannot be placed before a RETURN insn with a filled delay slot.
??? There may be a problem with the current implementation. Suppose
we start with a bare RETURN insn and call find_end_label. It may set
end_of_function_label just before the RETURN. Suppose the machinery
is able to fill the delay slot of the RETURN insn afterwards. Then
end_of_function_label is no longer valid according to the property
described above and find_end_label will still return it unmodified.
Note that this is probably mitigated by the following observation:
once end_of_function_label is made, it is very likely the target of
a jump, so filling the delay slot of the RETURN will be much more
difficult. */
static rtx
find_end_label (void)
......@@ -358,13 +360,15 @@ find_end_label (void)
/* When a target threads its epilogue we might already have a
suitable return insn. If so put a label before it for the
end_of_function_label. */
if (GET_CODE (insn) == BARRIER && return_insn_p (PREV_INSN (insn)))
if (GET_CODE (insn) == BARRIER
&& GET_CODE (PREV_INSN (insn)) == JUMP_INSN
&& GET_CODE (PATTERN (PREV_INSN (insn))) == RETURN)
{
rtx temp = PREV_INSN (PREV_INSN (insn));
end_of_function_label = gen_label_rtx ();
LABEL_NUSES (end_of_function_label) = 0;
/* Put the label before an USE insn that may precede the RETURN insn. */
/* Put the label before an USE insns that may precede the RETURN insn. */
while (GET_CODE (temp) == USE)
temp = PREV_INSN (temp);
......@@ -380,7 +384,8 @@ find_end_label (void)
/* If the basic block reorder pass moves the return insn to
some other place try to locate it again and put our
end_of_function_label there. */
while (insn && ! return_insn_p (insn))
while (insn && ! (GET_CODE (insn) == JUMP_INSN
&& (GET_CODE (PATTERN (insn)) == RETURN)))
insn = PREV_INSN (insn);
if (insn)
{
......@@ -395,6 +400,22 @@ find_end_label (void)
}
else
{
#ifdef HAVE_epilogue
if (HAVE_epilogue
#ifdef HAVE_return
&& ! HAVE_return
#endif
)
{
/* The RETURN insn has its delay slot filled so we cannot
emit the label just before it. Since we already have
an epilogue and cannot emit a new RETURN, we cannot
emit the label at all. */
end_of_function_label = NULL_RTX;
return end_of_function_label;
}
#endif /* HAVE_epilogue */
/* Otherwise, make a new label and emit a RETURN and BARRIER,
if needed. */
emit_label (end_of_function_label);
......@@ -742,7 +763,6 @@ optimize_skip (rtx insn)
rtx trial = next_nonnote_insn (insn);
rtx next_trial = next_active_insn (trial);
rtx delay_list = 0;
rtx target_label;
int flags;
flags = get_jump_flags (insn, JUMP_LABEL (insn));
......@@ -791,17 +811,20 @@ optimize_skip (rtx insn)
&& (simplejump_p (next_trial)
|| GET_CODE (PATTERN (next_trial)) == RETURN))
{
target_label = JUMP_LABEL (next_trial);
rtx target_label = JUMP_LABEL (next_trial);
if (target_label == 0)
target_label = find_end_label ();
/* Recompute the flags based on TARGET_LABEL since threading
the jump to TARGET_LABEL may change the direction of the
jump (which may change the circumstances in which the
delay slot is nullified). */
flags = get_jump_flags (insn, target_label);
if (eligible_for_annul_true (insn, 0, trial, flags))
reorg_redirect_jump (insn, target_label);
if (target_label)
{
/* Recompute the flags based on TARGET_LABEL since threading
the jump to TARGET_LABEL may change the direction of the
jump (which may change the circumstances in which the
delay slot is nullified). */
flags = get_jump_flags (insn, target_label);
if (eligible_for_annul_true (insn, 0, trial, flags))
reorg_redirect_jump (insn, target_label);
}
}
INSN_ANNULLED_BRANCH_P (insn) = 1;
......@@ -2373,15 +2396,18 @@ fill_simple_delay_slots (int non_jumps_p)
else
new_label = find_end_label ();
delay_list
= add_to_delay_list (copy_rtx (next_trial), delay_list);
slots_filled++;
reorg_redirect_jump (trial, new_label);
/* If we merged because we both jumped to the same place,
redirect the original insn also. */
if (target)
reorg_redirect_jump (insn, new_label);
if (new_label)
{
delay_list
= add_to_delay_list (copy_rtx (next_trial), delay_list);
slots_filled++;
reorg_redirect_jump (trial, new_label);
/* If we merged because we both jumped to the same place,
redirect the original insn also. */
if (target)
reorg_redirect_jump (insn, new_label);
}
}
}
......@@ -2926,7 +2952,8 @@ fill_slots_from_thread (rtx insn, rtx condition, rtx thread,
else
label = get_label_before (new_thread);
reorg_redirect_jump (insn, label);
if (label)
reorg_redirect_jump (insn, label);
}
return delay_list;
......@@ -3094,14 +3121,14 @@ relax_delay_slots (rtx first)
if (target_label == 0)
target_label = find_end_label ();
if (next_active_insn (target_label) == next
if (target_label && next_active_insn (target_label) == next
&& ! condjump_in_parallel_p (insn))
{
delete_jump (insn);
continue;
}
if (target_label != JUMP_LABEL (insn))
if (target_label && target_label != JUMP_LABEL (insn))
reorg_redirect_jump (insn, target_label);
/* See if this jump branches around an unconditional jump.
......@@ -3109,6 +3136,7 @@ relax_delay_slots (rtx first)
second jump. */
if (next && GET_CODE (next) == JUMP_INSN
&& (simplejump_p (next) || GET_CODE (PATTERN (next)) == RETURN)
&& target_label
&& next_active_insn (target_label) == next_active_insn (next)
&& no_labels_between_p (insn, next))
{
......@@ -3242,7 +3270,7 @@ relax_delay_slots (rtx first)
if (trial == 0)
trial = find_end_label ();
if (trial != target_label
if (trial && trial != target_label
&& redirect_with_delay_slots_safe_p (delay_insn, trial, insn))
{
reorg_redirect_jump (delay_insn, trial);
......@@ -3256,23 +3284,24 @@ relax_delay_slots (rtx first)
&& redundant_insn (trial, insn, 0)
&& ! can_throw_internal (trial))
{
rtx tmp;
/* Figure out where to emit the special USE insn so we don't
later incorrectly compute register live/death info. */
tmp = next_active_insn (trial);
rtx tmp = next_active_insn (trial);
if (tmp == 0)
tmp = find_end_label ();
/* Insert the special USE insn and update dataflow info. */
update_block (trial, tmp);
if (tmp)
{
/* Insert the special USE insn and update dataflow info. */
update_block (trial, tmp);
/* Now emit a label before the special USE insn, and
redirect our jump to the new label. */
target_label = get_label_before (PREV_INSN (tmp));
reorg_redirect_jump (delay_insn, target_label);
next = insn;
continue;
/* Now emit a label before the special USE insn, and
redirect our jump to the new label. */
target_label = get_label_before (PREV_INSN (tmp));
reorg_redirect_jump (delay_insn, target_label);
next = insn;
continue;
}
}
/* Similarly, if it is an unconditional jump with one insn in its
......@@ -3286,17 +3315,10 @@ relax_delay_slots (rtx first)
{
target_label = JUMP_LABEL (XVECEXP (PATTERN (trial), 0, 0));
if (target_label == 0)
{
target_label = find_end_label ();
/* The following condition may be true if TRIAL contains
the unique RETURN. In this case, threading would be
a nop and we would enter an infinite loop if we did it. */
if (next_active_insn (target_label) == trial)
target_label = 0;
}
target_label = find_end_label ();
if (target_label
&& redirect_with_delay_slots_safe_p (delay_insn, target_label,
&& redirect_with_delay_slots_safe_p (delay_insn, target_label,
insn))
{
reorg_redirect_jump (delay_insn, target_label);
......@@ -3382,7 +3404,8 @@ relax_delay_slots (rtx first)
label = find_end_label ();
/* find_end_label can generate a new label. Check this first. */
if (no_labels_between_p (insn, next)
if (label
&& no_labels_between_p (insn, next)
&& redirect_with_delay_slots_safe_p (delay_insn, label, insn))
{
/* Be careful how we do this to avoid deleting code or labels
......
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