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dump: implement cycle handling in has_backedge_to_worklist #46749

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Sep 21, 2022
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dump: implement cycle handling in has_backedge_to_worklist #46749

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140 changes: 95 additions & 45 deletions src/dump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -314,77 +314,127 @@ static int type_recursively_external(jl_datatype_t *dt) JL_NOTSAFEPOINT
return 1;
}

static void mark_backedges_in_worklist(jl_method_instance_t *mi, htable_t *visited, int found)
{
int oldfound = (char*)ptrhash_get(visited, mi) - (char*)HT_NOTFOUND;
if (oldfound < 3)
return; // not in-progress
ptrhash_put(visited, mi, (void*)((char*)HT_NOTFOUND + 1 + found));
#ifndef NDEBUG
jl_module_t *mod = mi->def.module;
if (jl_is_method(mod))
mod = ((jl_method_t*)mod)->module;
assert(jl_is_module(mod));
assert(!mi->precompiled && !module_in_worklist(mod));
assert(mi->backedges);
#endif
size_t i = 0, n = jl_array_len(mi->backedges);
while (i < n) {
jl_method_instance_t *be;
i = get_next_edge(mi->backedges, i, NULL, &be);
mark_backedges_in_worklist(be, visited, found);
}
}

// When we infer external method instances, ensure they link back to the
// package. Otherwise they might be, e.g., for external macros
static int has_backedge_to_worklist(jl_method_instance_t *mi, htable_t *visited)
static int has_backedge_to_worklist(jl_method_instance_t *mi, htable_t *visited, int depth)
{
void **bp = ptrhash_bp(visited, mi);
// HT_NOTFOUND: not yet analyzed
// HT_NOTFOUND + 1: doesn't link back
// HT_NOTFOUND + 2: does link back
if (*bp != HT_NOTFOUND)
return (char*)*bp - (char*)HT_NOTFOUND - 1;
*bp = (void*)((char*)HT_NOTFOUND + 1); // preliminarily mark as "not found"
// TODO: this algorithm deals with cycles incorrectly
jl_module_t *mod = mi->def.module;
if (jl_is_method(mod))
mod = ((jl_method_t*)mod)->module;
assert(jl_is_module(mod));
if (mi->precompiled || module_in_worklist(mod)) {
*bp = (void*)((char*)HT_NOTFOUND + 2); // found
return 1;
}
if (!mi->backedges) {
return 0;
}
void **bp = ptrhash_bp(visited, mi);
// HT_NOTFOUND: not yet analyzed
// HT_NOTFOUND + 1: no link back
// HT_NOTFOUND + 2: does link back
// HT_NOTFOUND + 3 + depth: in-progress
int found = (char*)*bp - (char*)HT_NOTFOUND;
if (found)
return found - 1;
*bp = (void*)((char*)HT_NOTFOUND + 3 + depth); // preliminarily mark as in-progress
size_t i = 0, n = jl_array_len(mi->backedges);
jl_method_instance_t *be;
int cycle = 0;
while (i < n) {
jl_method_instance_t *be;
i = get_next_edge(mi->backedges, i, NULL, &be);
if (has_backedge_to_worklist(be, visited)) {
bp = ptrhash_bp(visited, mi); // re-acquire since rehashing might change the location
*bp = (void*)((char*)HT_NOTFOUND + 2); // found
return 1;
int child_found = has_backedge_to_worklist(be, visited, depth + 1);
if (child_found == 1) {
found = 1;
break;
}
else if (child_found >= 2 && child_found - 2 < cycle) {
// record the cycle will resolve at depth "cycle"
cycle = child_found - 2;
assert(cycle);
}
}
return 0;
if (!found && cycle && cycle != depth)
return cycle + 2;
bp = ptrhash_bp(visited, mi); // re-acquire since rehashing might change the location
*bp = (void*)((char*)HT_NOTFOUND + 1 + found);
if (cycle) {
// If we are the top of the current cycle, now mark all other parts of
// our cycle by re-walking the backedges graph and marking all WIP
// items as found.
// Be careful to only re-walk as far as we had originally scanned above.
// Or if we found a backedge, also mark all of the other parts of the
// cycle as also having an backedge.
n = i;
i = 0;
while (i < n) {
jl_method_instance_t *be;
i = get_next_edge(mi->backedges, i, NULL, &be);
mark_backedges_in_worklist(be, visited, found);
}
}
return found;
}

// given the list of MethodInstances that were inferred during the
// build, select those that are external and have at least one
// relocatable CodeInstance.
// relocatable CodeInstance and are inferred to be called from the worklist
// or explicitly added by a precompile statement.
static size_t queue_external_mis(jl_array_t *list)
{
if (list == NULL)
return 0;
size_t i, n = 0;
htable_t visited;
if (list) {
assert(jl_is_array(list));
size_t n0 = jl_array_len(list);
htable_new(&visited, n0);
for (i = 0; i < n0; i++) {
jl_method_instance_t *mi = (jl_method_instance_t*)jl_array_ptr_ref(list, i);
assert(jl_is_method_instance(mi));
if (jl_is_method(mi->def.value)) {
jl_method_t *m = mi->def.method;
if (!module_in_worklist(m->module)) {
jl_code_instance_t *ci = mi->cache;
int relocatable = 0;
while (ci) {
if (ci->max_world == ~(size_t)0)
relocatable |= ci->relocatability;
ci = ci->next;
}
if (relocatable && ptrhash_get(&external_mis, mi) == HT_NOTFOUND) {
if (has_backedge_to_worklist(mi, &visited)) {
ptrhash_put(&external_mis, mi, mi);
n++;
}
assert(jl_is_array(list));
size_t n0 = jl_array_len(list);
htable_new(&visited, n0);
for (i = 0; i < n0; i++) {
jl_method_instance_t *mi = (jl_method_instance_t*)jl_array_ptr_ref(list, i);
assert(jl_is_method_instance(mi));
if (jl_is_method(mi->def.value)) {
jl_method_t *m = mi->def.method;
if (!module_in_worklist(m->module)) {
jl_code_instance_t *ci = mi->cache;
int relocatable = 0;
while (ci) {
if (ci->max_world == ~(size_t)0)
relocatable |= ci->relocatability;
ci = ci->next;
}
if (relocatable && ptrhash_get(&external_mis, mi) == HT_NOTFOUND) {
int found = has_backedge_to_worklist(mi, &visited, 1);
assert(found == 0 || found == 1);
if (found == 1) {
ptrhash_put(&external_mis, mi, mi);
n++;
}
}
}
}
htable_free(&visited);
}
htable_free(&visited);
return n;
}

Expand Down Expand Up @@ -1163,7 +1213,7 @@ static void serialize_htable_keys(jl_serializer_state *s, htable_t *ht, int nite
// or method instances not in the queue
//
// from MethodTables
static void jl_collect_missing_backedges_to_mod(jl_methtable_t *mt)
static void jl_collect_missing_backedges(jl_methtable_t *mt)
{
jl_array_t *backedges = mt->backedges;
if (backedges) {
Expand Down Expand Up @@ -1252,7 +1302,7 @@ static void jl_collect_extext_methods_from_mod(jl_array_t *s, jl_module_t *m) JL
(jl_value_t*)mt != jl_nothing &&
(mt != jl_type_type_mt && mt != jl_nonfunction_mt)) {
jl_collect_methtable_from_mod(s, mt);
jl_collect_missing_backedges_to_mod(mt);
jl_collect_missing_backedges(mt);
}
}
}
Expand Down Expand Up @@ -2850,11 +2900,11 @@ JL_DLLEXPORT int jl_save_incremental(const char *fname, jl_array_t *worklist)
jl_collect_extext_methods_from_mod(extext_methods, m);
}
jl_collect_methtable_from_mod(extext_methods, jl_type_type_mt);
jl_collect_missing_backedges_to_mod(jl_type_type_mt);
jl_collect_missing_backedges(jl_type_type_mt);
jl_collect_methtable_from_mod(extext_methods, jl_nonfunction_mt);
jl_collect_missing_backedges_to_mod(jl_nonfunction_mt);
jl_collect_missing_backedges(jl_nonfunction_mt);

// jl_collect_extext_methods_from_mod and jl_collect_missing_backedges_to_mod accumulate data in edges_map.
// jl_collect_extext_methods_from_mod and jl_collect_missing_backedges accumulate data in edges_map.
// Process this to extract `edges` and `ext_targets`.
jl_collect_backedges(edges, ext_targets);

Expand Down