struct loops *
loop_optimizer_init (FILE *dumpfile)
{
struct loops *loops = xcalloc (1, sizeof (struct loops));
edge e;
edge_iterator ei;
static bool first_time = true;
if (first_time)
{
first_time = false;
init_set_costs ();
}
/* Avoid annoying special cases of edges going to exit
block. */
for (ei = ei_start (EXIT_BLOCK_PTR->preds); (e = ei_safe_edge (ei)); )
if ((e->flags & EDGE_FALLTHRU) && !single_succ_p (e->src))
split_edge (e);
else
ei_next (&ei);
/* Find the loops. */
if (flow_loops_find (loops) <= 1)
{
/* No loops. */
flow_loops_free (loops);
free (loops);
return NULL;
}
/* Not going to update these. */
free (loops->cfg.rc_order);
loops->cfg.rc_order = NULL;
free (loops->cfg.dfs_order);
loops->cfg.dfs_order = NULL;
/* Create pre-headers. */
create_preheaders (loops, CP_SIMPLE_PREHEADERS);
/* Force all latches to have only single successor. */
force_single_succ_latches (loops);
/* Mark irreducible loops. */
mark_irreducible_loops (loops);
/* Dump loops. */
flow_loops_dump (loops, dumpfile, NULL, 1);
#ifdef ENABLE_CHECKING
verify_dominators (CDI_DOMINATORS);
verify_loop_structure (loops);
#endif
return loops;
}
static void
apply_loop_flags (unsigned flags)
{
if (flags & LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
{
/* If the loops may have multiple latches, we cannot canonicalize
them further (and most of the loop manipulation functions will
not work). However, we avoid modifying cfg, which some
passes may want. */
gcc_assert ((flags & ~(LOOPS_MAY_HAVE_MULTIPLE_LATCHES
| LOOPS_HAVE_RECORDED_EXITS)) == 0);
loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
}
else
disambiguate_loops_with_multiple_latches ();
/* Create pre-headers. */
if (flags & LOOPS_HAVE_PREHEADERS)
{
int cp_flags = CP_SIMPLE_PREHEADERS;
if (flags & LOOPS_HAVE_FALLTHRU_PREHEADERS)
cp_flags |= CP_FALLTHRU_PREHEADERS;
create_preheaders (cp_flags);
}
/* Force all latches to have only single successor. */
if (flags & LOOPS_HAVE_SIMPLE_LATCHES)
force_single_succ_latches ();
/* Mark irreducible loops. */
if (flags & LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
mark_irreducible_loops ();
if (flags & LOOPS_HAVE_RECORDED_EXITS)
record_loop_exits ();
}
