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QMessageAutenticationCode: add some Q_ASSUME()s to xored()

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... telling the compiler all there is to know about block.size(), so
it hopefully vectorizes the function well.

Pick-to: 6.5
Change-Id: Icb3d5c983402e52a65c72af15f806f3a3fe6411f
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Marc Mutz 2023-02-26 16:46:49 +01:00
parent c1e2ec16db
commit bcc6015a3a
1 changed files with 26 additions and 0 deletions
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26
src/corelib/tools/qcryptographichash.cpp
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@ -12,6 +12,8 @@
#include <private/qlocking_p.h>
#include <array>
#include <climits>
#include <numeric>
#include "../../3rdparty/sha1/sha1.cpp"
@ -1099,10 +1101,34 @@ constexpr int maxHashBlockSize()
return result;
}
[[maybe_unused]]
constexpr int minHashBlockSize()
{
int result = INT_MAX;
using A = QCryptographicHash::Algorithm;
for (int i = 0; i < A::NumAlgorithms ; ++i)
result = std::min(result, qt_hash_block_size(A(i)));
return result;
}
[[maybe_unused]]
constexpr int gcdHashBlockSize()
{
int result = 0;
using A = QCryptographicHash::Algorithm;
for (int i = 0; i < A::NumAlgorithms ; ++i)
result = std::gcd(result, qt_hash_block_size(A(i)));
return result;
}
using HashBlock = QSmallByteArray<maxHashBlockSize()>;
static HashBlock xored(const HashBlock &block, quint8 val) noexcept
{
// some hints for the optimizer:
Q_ASSUME(block.size() >= minHashBlockSize());
Q_ASSUME(block.size() <= maxHashBlockSize());
Q_ASSUME(block.size() % gcdHashBlockSize() == 0);
HashBlock result;
result.resizeForOverwrite(block.size());
for (qsizetype i = 0; i < block.size(); ++i)