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https://github.com/RGBCube/serenity
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LibRegex: Fully interpret the Compare Op when looking for overlaps
We had a really naive and simplistic implementation, which lead to various issues where the optimiser incorrectly rewrote the regex to use atomic groups; this commit fixes that.
This commit is contained in:
Ali Mohammad Pur
Andreas Kling
parent
b6f2ba6917
commit
6e655b7f89
4 changed files with 206 additions and 98 deletions
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@ -108,6 +108,182 @@ typename Regex<Parser>::BasicBlockList Regex<Parser>::split_basic_blocks(ByteCod
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return block_boundaries;
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}
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static bool has_overlap(Vector<CompareTypeAndValuePair> const& lhs, Vector<CompareTypeAndValuePair> const& rhs)
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{
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// We have to fully interpret the two sequences to determine if they overlap (that is, keep track of inversion state and what ranges they cover).
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bool inverse { false };
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bool temporary_inverse { false };
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bool reset_temporary_inverse { false };
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auto current_lhs_inversion_state = [&]() -> bool { return temporary_inverse ^ inverse; };
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RedBlackTree<u32, u32> lhs_ranges;
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RedBlackTree<u32, u32> lhs_negated_ranges;
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HashTable<CharClass> lhs_char_classes;
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HashTable<CharClass> lhs_negated_char_classes;
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auto range_contains = [&]<typename T>(T& value) -> bool {
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u32 start;
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u32 end;
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if constexpr (IsSame<T, CharRange>) {
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start = value.from;
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end = value.to;
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} else {
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start = value;
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end = value;
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}
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auto* max = lhs_ranges.find_smallest_not_below(start);
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return max && *max <= end;
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};
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auto char_class_contains = [&](CharClass const& value) -> bool {
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if (lhs_char_classes.contains(value))
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return true;
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if (lhs_negated_char_classes.contains(value))
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return false;
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// This char class might match something in the ranges we have, and checking that is far too expensive, so just bail out.
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return true;
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};
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for (auto const& pair : lhs) {
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if (reset_temporary_inverse) {
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reset_temporary_inverse = false;
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temporary_inverse = false;
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} else {
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reset_temporary_inverse = true;
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}
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switch (pair.type) {
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case CharacterCompareType::Inverse:
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inverse = !inverse;
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break;
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case CharacterCompareType::TemporaryInverse:
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temporary_inverse = !temporary_inverse;
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break;
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case CharacterCompareType::AnyChar:
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// Special case: if not inverted, AnyChar is always in the range.
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if (!current_lhs_inversion_state())
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return true;
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break;
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case CharacterCompareType::Char:
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if (!current_lhs_inversion_state())
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lhs_ranges.insert(pair.value, pair.value);
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else
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lhs_negated_ranges.insert(pair.value, pair.value);
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break;
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case CharacterCompareType::String:
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// FIXME: We just need to look at the last character of this string, but we only have the first character here.
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// Just bail out to avoid false positives.
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return true;
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case CharacterCompareType::CharClass:
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if (!current_lhs_inversion_state())
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lhs_char_classes.set(static_cast<CharClass>(pair.value));
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else
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lhs_negated_char_classes.set(static_cast<CharClass>(pair.value));
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break;
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case CharacterCompareType::CharRange: {
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auto range = bit_cast<CharRange>(pair.value);
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if (!current_lhs_inversion_state())
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lhs_ranges.insert(range.from, range.to);
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else
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lhs_negated_ranges.insert(range.from, range.to);
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break;
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}
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case CharacterCompareType::LookupTable:
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// We've transformed this into a series of ranges in flat_compares(), so bail out if we see it.
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return true;
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case CharacterCompareType::Reference:
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// We've handled this before coming here.
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break;
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case CharacterCompareType::Property:
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case CharacterCompareType::GeneralCategory:
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case CharacterCompareType::Script:
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case CharacterCompareType::ScriptExtension:
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// FIXME: These are too difficult to handle, so bail out.
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return true;
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case CharacterCompareType::Undefined:
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case CharacterCompareType::RangeExpressionDummy:
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// These do not occur in valid bytecode.
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VERIFY_NOT_REACHED();
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}
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}
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if constexpr (REGEX_DEBUG) {
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dbgln("lhs ranges:");
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for (auto it = lhs_ranges.begin(); it != lhs_ranges.end(); ++it)
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dbgln(" {}..{}", it.key(), *it);
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dbgln("lhs negated ranges:");
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for (auto it = lhs_negated_ranges.begin(); it != lhs_negated_ranges.end(); ++it)
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dbgln(" {}..{}", it.key(), *it);
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}
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for (auto const& pair : rhs) {
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if (reset_temporary_inverse) {
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reset_temporary_inverse = false;
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temporary_inverse = false;
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} else {
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reset_temporary_inverse = true;
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}
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dbgln_if(REGEX_DEBUG, "check {} ({})...", character_compare_type_name(pair.type), pair.value);
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switch (pair.type) {
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case CharacterCompareType::Inverse:
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inverse = !inverse;
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break;
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case CharacterCompareType::TemporaryInverse:
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temporary_inverse = !temporary_inverse;
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break;
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case CharacterCompareType::AnyChar:
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// Special case: if not inverted, AnyChar is always in the range.
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if (!current_lhs_inversion_state())
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return true;
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break;
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case CharacterCompareType::Char:
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if (!current_lhs_inversion_state() && range_contains(pair.value))
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return true;
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break;
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case CharacterCompareType::String:
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// FIXME: We just need to look at the last character of this string, but we only have the first character here.
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// Just bail out to avoid false positives.
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return true;
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case CharacterCompareType::CharClass:
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if (!current_lhs_inversion_state() && char_class_contains(static_cast<CharClass>(pair.value)))
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return true;
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break;
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case CharacterCompareType::CharRange: {
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auto range = bit_cast<CharRange>(pair.value);
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if (!current_lhs_inversion_state() && range_contains(range))
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return true;
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break;
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}
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case CharacterCompareType::LookupTable:
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// We've transformed this into a series of ranges in flat_compares(), so bail out if we see it.
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return true;
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case CharacterCompareType::Reference:
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// We've handled this before coming here.
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break;
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case CharacterCompareType::Property:
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case CharacterCompareType::GeneralCategory:
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case CharacterCompareType::Script:
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case CharacterCompareType::ScriptExtension:
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// FIXME: These are too difficult to handle, so bail out.
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return true;
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case CharacterCompareType::Undefined:
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case CharacterCompareType::RangeExpressionDummy:
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// These do not occur in valid bytecode.
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VERIFY_NOT_REACHED();
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}
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}
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return false;
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}
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enum class AtomicRewritePreconditionResult {
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SatisfiedWithProperHeader,
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SatisfiedWithEmptyHeader,
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@ -179,17 +355,9 @@ static AtomicRewritePreconditionResult block_satisfies_atomic_rewrite_preconditi
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}))
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return AtomicRewritePreconditionResult::NotSatisfied;
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for (auto& repeated_value : repeated_values) {
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// FIXME: This is too naive!
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if (any_of(repeated_value, [](auto& compare) { return compare.type == CharacterCompareType::AnyChar; }))
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return AtomicRewritePreconditionResult::NotSatisfied;
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if (any_of(repeated_values, [&](auto& repeated_value) { return has_overlap(compares, repeated_value); }))
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return AtomicRewritePreconditionResult::NotSatisfied;
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for (auto& repeated_compare : repeated_value) {
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// FIXME: This is too naive! it will miss _tons_ of cases since it doesn't check ranges!
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if (any_of(compares, [&](auto& compare) { return compare.type == repeated_compare.type && compare.value == repeated_compare.value; }))
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return AtomicRewritePreconditionResult::NotSatisfied;
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}
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}
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return AtomicRewritePreconditionResult::SatisfiedWithProperHeader;
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}
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case OpCodeId::CheckBegin:
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