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8352418: Add verification code to check that the associated loop nodes of useless Template Assertion Predicates are dead #24326

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8352418: Add verification code to check that the associated loop nodes of useless Template Assertion Predicates are dead #24326

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8352418: Add verification code to check that the associated loop node…
chhagedorn Mar 14, 2025
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chhagedorn Apr 2, 2025
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38 changes: 38 additions & 0 deletions src/hotspot/share/opto/predicates.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1240,8 +1240,46 @@ void EliminateUselessPredicates::mark_useful_predicates_for_loop(IdealLoopTree*
void EliminateUselessPredicates::mark_maybe_useful_predicates_useless() const {
mark_maybe_useful_predicates_on_list_useless(_parse_predicates);
mark_maybe_useful_predicates_on_list_useless(_template_assertion_predicate_opaques);
DEBUG_ONLY(verify_loop_nodes_of_useless_templates_assertion_predicates_are_dead();)
}

#ifdef ASSERT
// All now useless Template Assertion Predicates should not refer to any CountedLoopNode that can still be found in the
// graph (otherwise, they would have been marked useful instead). This is verified in this method.
void EliminateUselessPredicates::verify_loop_nodes_of_useless_templates_assertion_predicates_are_dead() const {
ResourceMark rm;
Unique_Node_List loop_nodes_of_useless_template_assertion_predicates =
collect_loop_nodes_of_useless_template_assertion_predicates();
verify_associated_loop_nodes_are_dead(loop_nodes_of_useless_template_assertion_predicates);
}

Unique_Node_List EliminateUselessPredicates::collect_loop_nodes_of_useless_template_assertion_predicates() const {
Unique_Node_List loop_nodes_of_useless_template_assertion_predicates;
for (int i = 0; i < _template_assertion_predicate_opaques.length(); i++) {
OpaqueTemplateAssertionPredicateNode* opaque_node = _template_assertion_predicate_opaques.at(i);
if (opaque_node->is_useless()) {
loop_nodes_of_useless_template_assertion_predicates.push(opaque_node->loop_node());
}
}
return loop_nodes_of_useless_template_assertion_predicates;
}

void EliminateUselessPredicates::verify_associated_loop_nodes_are_dead(
const Unique_Node_List& loop_nodes_of_useless_template_assertion_predicates) const {
if (loop_nodes_of_useless_template_assertion_predicates.size() == 0) {
return;
}
for (LoopTreeIterator iterator(_ltree_root); !iterator.done(); iterator.next()) {
IdealLoopTree* loop = iterator.current();
Node* loop_head = loop->head();
if (loop_head->is_CountedLoop()) {
assert(!loop_nodes_of_useless_template_assertion_predicates.member(loop_head),
"CountedLoopNode should be dead when found in OpaqueTemplateAssertionPredicateNode being marked useless");
}
}
}
#endif // ASSERT

template<class PredicateList>
void EliminateUselessPredicates::mark_maybe_useful_predicates_on_list_useless(
const PredicateList& predicate_list) const {
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5 changes: 5 additions & 0 deletions src/hotspot/share/opto/predicates.hpp
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Expand Up @@ -1254,6 +1254,11 @@ class EliminateUselessPredicates : public StackObj {
template <class PredicateList>
void mark_maybe_useful_predicates_on_list_useless(const PredicateList& predicate_list) const;

#ifdef ASSERT
void verify_loop_nodes_of_useless_templates_assertion_predicates_are_dead() const;
Unique_Node_List collect_loop_nodes_of_useless_template_assertion_predicates() const;
void verify_associated_loop_nodes_are_dead(const Unique_Node_List& loop_nodes_of_useless_template_assertion_predicates) const;
#endif // ASSERT
public:
EliminateUselessPredicates(PhaseIterGVN& igvn, IdealLoopTree* ltree_root)
: C(igvn.C), _parse_predicates(igvn.C->parse_predicates()),
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