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;
}
void
loop_optimizer_init (unsigned flags)
{
timevar_push (TV_LOOP_INIT);
if (!current_loops)
{
gcc_assert (!(cfun->curr_properties & PROP_loops));
/* Find the loops. */
current_loops = flow_loops_find (NULL);
}
else
{
bool recorded_exits = loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS);
bool needs_fixup = loops_state_satisfies_p (LOOPS_NEED_FIXUP);
gcc_assert (cfun->curr_properties & PROP_loops);
/* Ensure that the dominators are computed, like flow_loops_find does. */
calculate_dominance_info (CDI_DOMINATORS);
#ifdef ENABLE_CHECKING
if (!needs_fixup)
verify_loop_structure ();
#endif
/* Clear all flags. */
if (recorded_exits)
release_recorded_exits ();
loops_state_clear (~0U);
if (needs_fixup)
{
/* Apply LOOPS_MAY_HAVE_MULTIPLE_LATCHES early as fix_loop_structure
re-applies flags. */
loops_state_set (flags & LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
fix_loop_structure (NULL);
}
}
/* Apply flags to loops. */
apply_loop_flags (flags);
/* Dump loops. */
flow_loops_dump (dump_file, NULL, 1);
#ifdef ENABLE_CHECKING
verify_loop_structure ();
#endif
timevar_pop (TV_LOOP_INIT);
}
/* Finalize loop optimizer. */
void
loop_optimizer_finalize (struct loops *loops, FILE *dumpfile)
{
unsigned i;
if (!loops)
return;
for (i = 1; i < loops->num; i++)
if (loops->parray[i])
free_simple_loop_desc (loops->parray[i]);
/* Another dump. */
flow_loops_dump (loops, dumpfile, NULL, 1);
/* Clean up. */
flow_loops_free (loops);
free (loops);
/* Checking. */
#ifdef ENABLE_CHECKING
verify_flow_info ();
#endif
}
static funct_state
analyze_function (struct cgraph_node *fn, bool ipa)
{
tree decl = fn->symbol.decl;
funct_state l;
basic_block this_block;
l = XCNEW (struct funct_state_d);
l->pure_const_state = IPA_CONST;
l->state_previously_known = IPA_NEITHER;
l->looping_previously_known = true;
l->looping = false;
l->can_throw = false;
state_from_flags (&l->state_previously_known, &l->looping_previously_known,
flags_from_decl_or_type (fn->symbol.decl),
cgraph_node_cannot_return (fn));
if (fn->thunk.thunk_p || fn->symbol.alias)
{
/* Thunk gets propagated through, so nothing interesting happens. */
gcc_assert (ipa);
return l;
}
if (dump_file)
{
fprintf (dump_file, "\n\n local analysis of %s\n ",
cgraph_node_name (fn));
}
push_cfun (DECL_STRUCT_FUNCTION (decl));
FOR_EACH_BB (this_block)
{
gimple_stmt_iterator gsi;
struct walk_stmt_info wi;
memset (&wi, 0, sizeof(wi));
for (gsi = gsi_start_bb (this_block);
!gsi_end_p (gsi);
gsi_next (&gsi))
{
check_stmt (&gsi, l, ipa);
if (l->pure_const_state == IPA_NEITHER && l->looping && l->can_throw)
goto end;
}
}
end:
if (l->pure_const_state != IPA_NEITHER)
{
/* Const functions cannot have back edges (an
indication of possible infinite loop side
effect. */
if (mark_dfs_back_edges ())
{
/* Preheaders are needed for SCEV to work.
Simple latches and recorded exits improve chances that loop will
proved to be finite in testcases such as in loop-15.c
and loop-24.c */
loop_optimizer_init (LOOPS_HAVE_PREHEADERS
| LOOPS_HAVE_SIMPLE_LATCHES
| LOOPS_HAVE_RECORDED_EXITS);
if (dump_file && (dump_flags & TDF_DETAILS))
flow_loops_dump (dump_file, NULL, 0);
if (mark_irreducible_loops ())
{
if (dump_file)
fprintf (dump_file, " has irreducible loops\n");
l->looping = true;
}
else
{
loop_iterator li;
struct loop *loop;
scev_initialize ();
FOR_EACH_LOOP (li, loop, 0)
if (!finite_loop_p (loop))
{
if (dump_file)
fprintf (dump_file, " can not prove finiteness of "
"loop %i\n", loop->num);
l->looping =true;
FOR_EACH_LOOP_BREAK (li);
}
scev_finalize ();
}
loop_optimizer_finalize ();
}
}
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, " checking previously known:");
better_state (&l->pure_const_state, &l->looping,
l->state_previously_known,
l->looping_previously_known);
if (TREE_NOTHROW (decl))
l->can_throw = false;
pop_cfun ();
if (dump_file)
{
if (l->looping)
fprintf (dump_file, "Function is locally looping.\n");
if (l->can_throw)
fprintf (dump_file, "Function is locally throwing.\n");
if (l->pure_const_state == IPA_CONST)
fprintf (dump_file, "Function is locally const.\n");
if (l->pure_const_state == IPA_PURE)
fprintf (dump_file, "Function is locally pure.\n");
}
return l;
}