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Yul: Avoid expensive operations in functions called very often #15574

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Nov 20, 2024
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Yul: Avoid expensive operations in functions called very often #15574

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8548a93
Yul: Avoid expensive check in frequently called function
blishko Nov 14, 2024
5150015
Yul: Avoid expensive check against std::regex when possible
blishko Nov 14, 2024
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7 changes: 6 additions & 1 deletion libyul/AsmParser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -147,12 +147,17 @@ void Parser::fetchDebugDataFromComment()
{
solAssert(m_sourceNames.has_value(), "");

std::string_view commentLiteral = m_scanner->currentCommentLiteral();
if (commentLiteral.empty())
{
m_astIDFromComment = std::nullopt;
return;
}
static std::regex const tagRegex = std::regex(
R"~~((?:^|\s+)(@[a-zA-Z0-9\-_]+)(?:\s+|$))~~", // tag, e.g: @src
std::regex_constants::ECMAScript | std::regex_constants::optimize
);

std::string_view commentLiteral = m_scanner->currentCommentLiteral();
std::match_results<std::string_view::const_iterator> match;

langutil::SourceLocation originLocation = m_locationFromComment;
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5 changes: 2 additions & 3 deletions libyul/optimiser/SyntacticalEquality.cpp
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Expand Up @@ -64,9 +64,8 @@ bool SyntacticallyEqual::expressionEqual(Identifier const& _lhs, Identifier cons
}
bool SyntacticallyEqual::expressionEqual(Literal const& _lhs, Literal const& _rhs)
{
yulAssert(validLiteral(_lhs), "Invalid lhs literal during syntactical equality check");
yulAssert(validLiteral(_rhs), "Invalid rhs literal during syntactical equality check");

assert(validLiteral(_lhs));
assert(validLiteral(_rhs));
Comment on lines +67 to +68
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@matheusaaguiar matheusaaguiar Nov 20, 2024 •
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Is this really significant? validLiteral is still being called twice.

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I'd myself just have removed these entirely. Any assertion that we deem ok to just do non-release we might as well not do at all in our context. But whatever, no need to keep this waiting.

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@cameel cameel Nov 21, 2024 •
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Any assertion that we deem ok to just do non-release we might as well not do at all in our context.

I don't agree. The standard assert macro is perfectly fine as a baseline for sanity checks and even when disabled still adds value by documenting the assumptions. Having asserts checked in release builds is definitely nice to have and saved us many times, but when they're too costly I'd still rather fall back to using assert than remove them completely.

The method validLiteral is nontrivial and should not be called (twice!) on every call to the equality comparison.
It might be desirable to re-introduce the check in a more suitable place.

We're asserting validity here because == does not compare the whole LiteralValue. This is fine for valid literals but not in general and I don't think that's obvious.

A better place for these checks would be the implementation of ==, but that would introduce a circular dependency. And would not make it less costly anyway.

return _lhs.value == _rhs.value;
}

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