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[FileCheck] Limit quadratic partial-match search behavior #147833

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Merged
merged 1 commit into from
Jul 23, 2025
Merged

[FileCheck] Limit quadratic partial-match search behavior #147833

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6 changes: 6 additions & 0 deletions llvm/lib/FileCheck/FileCheck.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1360,6 +1360,12 @@ void Pattern::printFuzzyMatch(const SourceMgr &SM, StringRef Buffer,
size_t Best = StringRef::npos;
double BestQuality = 0;

// Arbitrarily limit quadratic search behavior stemming from long CHECK lines.
if (size_t(4096) * size_t(2048) <
std::min(size_t(4096), Buffer.size()) *
std::max(FixedStr.size(), RegExStr.size()))
return;

// Use an arbitrary 4k limit on how far we will search.
for (size_t i = 0, e = std::min(size_t(4096), Buffer.size()); i != e; ++i) {
if (Buffer[i] == '\n')
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9 changes: 9 additions & 0 deletions llvm/test/FileCheck/long-check.txt
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