/* Sequentially order blocks and compact the arrays. */
void
compact_blocks (void)
{
int i;
SET_BASIC_BLOCK (ENTRY_BLOCK, ENTRY_BLOCK_PTR);
SET_BASIC_BLOCK (EXIT_BLOCK, EXIT_BLOCK_PTR);
if (df)
df_compact_blocks ();
else
{
basic_block bb;
i = NUM_FIXED_BLOCKS;
FOR_EACH_BB (bb)
{
SET_BASIC_BLOCK (i, bb);
bb->index = i;
i++;
}
gcc_assert (i == n_basic_blocks);
for (; i < last_basic_block; i++)
SET_BASIC_BLOCK (i, NULL);
}
last_basic_block = n_basic_blocks;
}
void
expunge_block (basic_block b)
{
unlink_block (b);
SET_BASIC_BLOCK (b->index, NULL);
n_basic_blocks--;
/* We should be able to ggc_free here, but we are not.
The dead SSA_NAMES are left pointing to dead statements that are pointing
to dead basic blocks making garbage collector to die.
We should be able to release all dead SSA_NAMES and at the same time we should
clear out BB pointer of dead statements consistently. */
}
static void
fixup_reorder_chain (void)
{
basic_block bb, prev_bb;
int index;
rtx insn = NULL;
if (cfg_layout_function_header)
{
set_first_insn (cfg_layout_function_header);
insn = cfg_layout_function_header;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
/* First do the bulk reordering -- rechain the blocks without regard to
the needed changes to jumps and labels. */
for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
bb != 0;
bb = bb->aux, index++)
{
if (bb->il.rtl->header)
{
if (insn)
NEXT_INSN (insn) = bb->il.rtl->header;
else
set_first_insn (bb->il.rtl->header);
PREV_INSN (bb->il.rtl->header) = insn;
insn = bb->il.rtl->header;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
if (insn)
NEXT_INSN (insn) = BB_HEAD (bb);
else
set_first_insn (BB_HEAD (bb));
PREV_INSN (BB_HEAD (bb)) = insn;
insn = BB_END (bb);
if (bb->il.rtl->footer)
{
NEXT_INSN (insn) = bb->il.rtl->footer;
PREV_INSN (bb->il.rtl->footer) = insn;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
}
}
gcc_assert (index == n_basic_blocks);
NEXT_INSN (insn) = cfg_layout_function_footer;
if (cfg_layout_function_footer)
PREV_INSN (cfg_layout_function_footer) = insn;
while (NEXT_INSN (insn))
insn = NEXT_INSN (insn);
set_last_insn (insn);
#ifdef ENABLE_CHECKING
verify_insn_chain ();
#endif
delete_dead_jumptables ();
/* Now add jumps and labels as needed to match the blocks new
outgoing edges. */
for (bb = ENTRY_BLOCK_PTR->next_bb; bb ; bb = bb->aux)
{
edge e_fall, e_taken, e;
rtx bb_end_insn;
basic_block nb;
edge_iterator ei;
if (EDGE_COUNT (bb->succs) == 0)
continue;
/* Find the old fallthru edge, and another non-EH edge for
a taken jump. */
e_taken = e_fall = NULL;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_FALLTHRU)
e_fall = e;
else if (! (e->flags & EDGE_EH))
e_taken = e;
bb_end_insn = BB_END (bb);
if (JUMP_P (bb_end_insn))
{
if (any_condjump_p (bb_end_insn))
{
/* If the old fallthru is still next, nothing to do. */
if (bb->aux == e_fall->dest
|| e_fall->dest == EXIT_BLOCK_PTR)
continue;
/* The degenerated case of conditional jump jumping to the next
instruction can happen for jumps with side effects. We need
to construct a forwarder block and this will be done just
fine by force_nonfallthru below. */
if (!e_taken)
;
/* There is another special case: if *neither* block is next,
such as happens at the very end of a function, then we'll
need to add a new unconditional jump. Choose the taken
edge based on known or assumed probability. */
else if (bb->aux != e_taken->dest)
{
rtx note = find_reg_note (bb_end_insn, REG_BR_PROB, 0);
if (note
&& INTVAL (XEXP (note, 0)) < REG_BR_PROB_BASE / 2
&& invert_jump (bb_end_insn,
(e_fall->dest == EXIT_BLOCK_PTR
? NULL_RTX
: label_for_bb (e_fall->dest)), 0))
{
e_fall->flags &= ~EDGE_FALLTHRU;
#ifdef ENABLE_CHECKING
gcc_assert (could_fall_through
(e_taken->src, e_taken->dest));
#endif
e_taken->flags |= EDGE_FALLTHRU;
update_br_prob_note (bb);
e = e_fall, e_fall = e_taken, e_taken = e;
}
}
/* If the "jumping" edge is a crossing edge, and the fall
through edge is non-crossing, leave things as they are. */
else if ((e_taken->flags & EDGE_CROSSING)
&& !(e_fall->flags & EDGE_CROSSING))
continue;
/* Otherwise we can try to invert the jump. This will
basically never fail, however, keep up the pretense. */
else if (invert_jump (bb_end_insn,
(e_fall->dest == EXIT_BLOCK_PTR
? NULL_RTX
: label_for_bb (e_fall->dest)), 0))
{
e_fall->flags &= ~EDGE_FALLTHRU;
#ifdef ENABLE_CHECKING
gcc_assert (could_fall_through
(e_taken->src, e_taken->dest));
#endif
e_taken->flags |= EDGE_FALLTHRU;
update_br_prob_note (bb);
continue;
}
}
else
{
/* Otherwise we have some return, switch or computed
jump. In the 99% case, there should not have been a
fallthru edge. */
gcc_assert (returnjump_p (bb_end_insn) || !e_fall);
continue;
}
}
else
{
/* No fallthru implies a noreturn function with EH edges, or
something similarly bizarre. In any case, we don't need to
do anything. */
if (! e_fall)
continue;
/* If the fallthru block is still next, nothing to do. */
if (bb->aux == e_fall->dest)
continue;
/* A fallthru to exit block. */
if (e_fall->dest == EXIT_BLOCK_PTR)
continue;
}
/* We got here if we need to add a new jump insn. */
nb = force_nonfallthru (e_fall);
if (nb)
{
nb->il.rtl->visited = 1;
nb->aux = bb->aux;
bb->aux = nb;
/* Don't process this new block. */
bb = nb;
/* Make sure new bb is tagged for correct section (same as
fall-thru source, since you cannot fall-throu across
section boundaries). */
BB_COPY_PARTITION (e_fall->src, single_pred (bb));
if (flag_reorder_blocks_and_partition
&& targetm.have_named_sections
&& JUMP_P (BB_END (bb))
&& !any_condjump_p (BB_END (bb))
&& (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
(REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
}
}
/* Put basic_block_info in the new order. */
if (dump_file)
{
fprintf (dump_file, "Reordered sequence:\n");
for (bb = ENTRY_BLOCK_PTR->next_bb, index = NUM_FIXED_BLOCKS;
bb;
bb = bb->aux, index++)
{
fprintf (dump_file, " %i ", index);
if (get_bb_original (bb))
fprintf (dump_file, "duplicate of %i ",
get_bb_original (bb)->index);
else if (forwarder_block_p (bb)
&& !LABEL_P (BB_HEAD (bb)))
fprintf (dump_file, "compensation ");
else
fprintf (dump_file, "bb %i ", bb->index);
fprintf (dump_file, " [%i]\n", bb->frequency);
}
}
prev_bb = ENTRY_BLOCK_PTR;
bb = ENTRY_BLOCK_PTR->next_bb;
index = NUM_FIXED_BLOCKS;
for (; bb; prev_bb = bb, bb = bb->aux, index ++)
{
bb->index = index;
SET_BASIC_BLOCK (index, bb);
bb->prev_bb = prev_bb;
prev_bb->next_bb = bb;
}
prev_bb->next_bb = EXIT_BLOCK_PTR;
EXIT_BLOCK_PTR->prev_bb = prev_bb;
/* Annoying special case - jump around dead jumptables left in the code. */
FOR_EACH_BB (bb)
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
if (e->flags & EDGE_FALLTHRU)
break;
if (e && !can_fallthru (e->src, e->dest))
force_nonfallthru (e);
}
}