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LibCrypto: Manage vector sizing manually in performance-critical places

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Use Vector::resize_and_keep_capacity() to resize BigInt vectors to just
the right size without risking deallocation. Then do direct indexed
accesses to the underlying words (or use memset/memcpy.)

This gives a ~40% speed-up on the RSA tests in "test-crypto -t pk" :^)
This commit is contained in:
Andreas Kling 2020-05-03 19:00:56 +02:00
parent baadde122b
commit e6922c0d40
1 changed files with 17 additions and 25 deletions
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42
Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
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@ -110,17 +110,15 @@ void UnsignedBigInteger::set_to_0()
void UnsignedBigInteger::set_to(u32 other)
{
m_is_invalid = false;
m_words.clear_with_capacity();
m_words.append(other);
m_words.resize_and_keep_capacity(1);
m_words[0] = other;
}
void UnsignedBigInteger::set_to(const UnsignedBigInteger& other)
{
m_is_invalid = other.m_is_invalid;
m_words.clear_with_capacity();
m_words.ensure_capacity(other.m_words.size());
for (size_t i = 0; i < other.m_words.size(); ++i)
m_words.unchecked_append(other.m_words[i]);
m_words.resize_and_keep_capacity(other.m_words.size());
__builtin_memcpy(m_words.data(), other.m_words.data(), other.m_words.size() * sizeof(u32));
}
size_t UnsignedBigInteger::trimmed_length() const
@ -212,15 +210,13 @@ void UnsignedBigInteger::set_bit_inplace(size_t bit_index)
bool UnsignedBigInteger::operator==(const UnsignedBigInteger& other) const
{
if (is_invalid() != other.is_invalid())
return false;
auto length = trimmed_length();
if (length != other.trimmed_length()) {
if (length != other.trimmed_length())
return false;
}
if (is_invalid() != other.is_invalid()) {
return false;
}
return !__builtin_memcmp(m_words.data(), other.words().data(), length);
}
@ -268,7 +264,7 @@ void UnsignedBigInteger::add_without_allocation(
u8 carry = 0;
output.set_to_0();
output.m_words.ensure_capacity(longer->length() + 1);
output.m_words.resize_and_keep_capacity(longer->length());
for (size_t i = 0; i < shorter->length(); ++i) {
u32 word_addition_result = shorter->m_words[i] + longer->m_words[i];
@ -281,7 +277,7 @@ void UnsignedBigInteger::add_without_allocation(
word_addition_result++;
}
carry = carry_out;
output.m_words.unchecked_append(word_addition_result);
output.m_words[i] = word_addition_result;
}
for (size_t i = shorter->length(); i < longer->length(); ++i) {
@ -291,10 +287,10 @@ void UnsignedBigInteger::add_without_allocation(
if (word_addition_result < longer->m_words[i]) {
carry = 1;
}
output.m_words.unchecked_append(word_addition_result);
output.m_words[i] = word_addition_result;
}
if (carry) {
output.m_words.unchecked_append(carry);
output.m_words.append(carry);
}
}
@ -316,7 +312,7 @@ void UnsignedBigInteger::subtract_without_allocation(
auto other_length = right.length();
output.set_to_0();
output.m_words.ensure_capacity(own_length);
output.m_words.resize_and_keep_capacity(own_length);
for (size_t i = 0; i < own_length; ++i) {
u32 other_word = (i < other_length) ? right.m_words[i] : 0;
@ -326,7 +322,7 @@ void UnsignedBigInteger::subtract_without_allocation(
if (temp < 0) {
temp += (UINT32_MAX + 1);
}
output.m_words.append(temp);
output.m_words[i] = temp;
}
// This assertion should not fail, because we verified that *this>=other at the beginning of the function
@ -495,14 +491,10 @@ ALWAYS_INLINE void UnsignedBigInteger::shift_left_by_n_words(
{
// shifting left by N words means just inserting N zeroes to the beginning of the words vector
output.set_to_0();
output.m_words.ensure_capacity(number_of_words + number.length());
output.m_words.resize_and_keep_capacity(number_of_words + number.length());
for (size_t i = 0; i < number_of_words; ++i) {
output.m_words.unchecked_append(0);
}
for (size_t i = 0; i < number.length(); ++i) {
output.m_words.unchecked_append(number.m_words[i]);
}
__builtin_memset(output.m_words.data(), 0, number_of_words * sizeof(unsigned));
__builtin_memcpy(&output.m_words.data()[number_of_words], number.m_words.data(), number.m_words.size() * sizeof(unsigned));
}
/**