void
alloc_aux_for_edges (int size)
{
static int initialized;
if (!initialized)
{
gcc_obstack_init (&edge_aux_obstack);
initialized = 1;
}
else
/* Check whether AUX data are still allocated. */
gcc_assert (!first_edge_aux_obj);
first_edge_aux_obj = obstack_alloc (&edge_aux_obstack, 0);
if (size)
{
basic_block bb;
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
alloc_aux_for_edge (e, size);
}
}
/* Redirect edge and update latch and header info. */
static void
redirect_edge_with_latch_update (edge e, basic_block to)
{
basic_block jump;
jump = redirect_edge_and_branch_force (e, to);
if (jump)
{
alloc_aux_for_block (jump, sizeof (int));
HEADER_BLOCK (jump) = 0;
alloc_aux_for_edge (jump->pred, sizeof (int));
LATCH_EDGE (jump->succ) = LATCH_EDGE (e);
LATCH_EDGE (jump->pred) = 0;
}
}
static basic_block
make_forwarder_block (basic_block bb, int redirect_latch, int redirect_nonlatch, edge except, int conn_latch)
{
edge e, next_e, fallthru;
basic_block dummy;
rtx insn;
insn = PREV_INSN (first_insn_after_basic_block_note (bb));
/* For empty block split_block will return NULL. */
if (BB_END (bb) == insn)
emit_note_after (NOTE_INSN_DELETED, insn);
fallthru = split_block (bb, insn);
dummy = fallthru->src;
bb = fallthru->dest;
bb->aux = xmalloc (sizeof (int));
HEADER_BLOCK (dummy) = 0;
HEADER_BLOCK (bb) = 1;
/* Redirect back edges we want to keep. */
for (e = dummy->pred; e; e = next_e)
{
next_e = e->pred_next;
if (e == except
|| !((redirect_latch && LATCH_EDGE (e))
|| (redirect_nonlatch && !LATCH_EDGE (e))))
{
dummy->frequency -= EDGE_FREQUENCY (e);
dummy->count -= e->count;
if (dummy->frequency < 0)
dummy->frequency = 0;
if (dummy->count < 0)
dummy->count = 0;
redirect_edge_with_latch_update (e, bb);
}
}
alloc_aux_for_edge (fallthru, sizeof (int));
LATCH_EDGE (fallthru) = conn_latch;
return dummy;
}
/* Takes care of merging natural loops with shared headers. */
static void
canonicalize_loop_headers (void)
{
basic_block header;
edge e;
/* Compute the dominators. */
calculate_dominance_info (CDI_DOMINATORS);
alloc_aux_for_blocks (sizeof (int));
alloc_aux_for_edges (sizeof (int));
/* Split blocks so that each loop has only single latch. */
FOR_EACH_BB (header)
{
int num_latches = 0;
int have_abnormal_edge = 0;
for (e = header->pred; e; e = e->pred_next)
{
basic_block latch = e->src;
if (e->flags & EDGE_ABNORMAL)
have_abnormal_edge = 1;
if (latch != ENTRY_BLOCK_PTR
&& dominated_by_p (CDI_DOMINATORS, latch, header))
{
num_latches++;
LATCH_EDGE (e) = 1;
}
}
if (have_abnormal_edge)
HEADER_BLOCK (header) = 0;
else
HEADER_BLOCK (header) = num_latches;
}
free_dominance_info (CDI_DOMINATORS);
if (HEADER_BLOCK (ENTRY_BLOCK_PTR->succ->dest))
{
basic_block bb;
/* We could not redirect edges freely here. On the other hand,
we can simply split the edge from entry block. */
bb = split_edge (ENTRY_BLOCK_PTR->succ);
alloc_aux_for_edge (bb->succ, sizeof (int));
LATCH_EDGE (bb->succ) = 0;
alloc_aux_for_block (bb, sizeof (int));
HEADER_BLOCK (bb) = 0;
}
FOR_EACH_BB (header)
{
int num_latch;
int want_join_latch;
int max_freq, is_heavy;
edge heavy;
if (!HEADER_BLOCK (header))
continue;
num_latch = HEADER_BLOCK (header);
want_join_latch = (num_latch > 1);
if (!want_join_latch)
continue;
/* Find a heavy edge. */
is_heavy = 1;
heavy = NULL;
max_freq = 0;
for (e = header->pred; e; e = e->pred_next)
if (LATCH_EDGE (e) &&
EDGE_FREQUENCY (e) > max_freq)
max_freq = EDGE_FREQUENCY (e);
for (e = header->pred; e; e = e->pred_next)
if (LATCH_EDGE (e) &&
EDGE_FREQUENCY (e) >= max_freq / HEAVY_EDGE_RATIO)
{
if (heavy)
{
is_heavy = 0;
break;
}
else
heavy = e;
}
if (is_heavy)
{
basic_block new_header =
make_forwarder_block (header, true, true, heavy, 0);
if (num_latch > 2)
make_forwarder_block (new_header, true, false, NULL, 1);
}
else
make_forwarder_block (header, true, false, NULL, 1);
}
free_aux_for_blocks ();
free_aux_for_edges ();
}
