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QByteArray: don't recurse when needle or replacement alias *this

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While the idea to delay the construction of the QVLAs until we know we
need them is elegant, we're doing a lot of checks twice or thrice this
way, so merely re-set the a, b pointers and otherwise continue
executing.

This requires us to default-construct the QVLAs before potentially
assign()ing to them, but that ought to be cheap, given the compiler
can see everything that's going on in QVLA.

Pick-to: 6.9 6.8 6.5
Change-Id: I4e42d5ab48711af91cc1785171524be5fb45ae2f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>
This commit is contained in:
Marc Mutz 2025-02-19 13:48:37 +01:00
parent b93575de01
commit 4308ab70ca
1 changed files with 5 additions and 4 deletions
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9
src/corelib/text/qbytearray.cpp
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@ -2537,13 +2537,14 @@ QByteArray &QByteArray::replace(QByteArrayView before, QByteArrayView after)
return *this; return *this;
// protect against before or after being part of this // protect against before or after being part of this
QVarLengthArray<char> pinnedNeedle, pinnedReplacement;
if (QtPrivate::q_points_into_range(a, d)) { if (QtPrivate::q_points_into_range(a, d)) {
QVarLengthArray copy(a, a + asize); pinnedReplacement.assign(a, a + asize);
return replace(before, QByteArrayView{copy}); a = pinnedReplacement.data();
} }
if (QtPrivate::q_points_into_range(b, d)) { if (QtPrivate::q_points_into_range(b, d)) {
QVarLengthArray copy(b, b + bsize); pinnedNeedle.assign(b, b + bsize);
return replace(QByteArrayView{copy}, after); b = pinnedNeedle.data();
} }
QByteArrayMatcher matcher(b, bsize); QByteArrayMatcher matcher(b, bsize);