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testing the-moisrex's recommended approach #549

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testing the-moisrex's recommended approach #549

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148 changes: 39 additions & 109 deletions src/helpers.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -197,131 +197,61 @@ ada_really_inline uint64_t swap_bytes_if_big_endian(uint64_t val) noexcept {
#endif
}

// : / [ \\ ?
static constexpr bool special_host_delimiters[256] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

// : / [ ?
static constexpr bool host_delimiters[256] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

// starting at index location, this finds the next location of a character
// :, /, \\, ? or [. If none is found, view.size() is returned.
// For use within get_host_delimiter_location.
// ['0x3a', '0x2f', '0x5c', '0x3f', '0x5b']
ada_really_inline size_t find_next_host_delimiter_special(
std::string_view view, size_t location) noexcept {
// performance: if you plan to call find_next_host_delimiter more than once,
// you *really* want find_next_host_delimiter to be inlined, because
// otherwise, the constants may get reloaded each time (bad).
auto has_zero_byte = [](uint64_t v) {
return ((v - 0x0101010101010101) & ~(v)&0x8080808080808080);
};
auto index_of_first_set_byte = [](uint64_t v) {
return ((((v - 1) & 0x101010101010101) * 0x101010101010101) >> 56) - 1;
};
auto broadcast = [](uint8_t v) -> uint64_t {
return 0x101010101010101ull * v;
};
size_t i = location;
uint64_t mask1 = broadcast(':');
uint64_t mask2 = broadcast('/');
uint64_t mask3 = broadcast('\\');
uint64_t mask4 = broadcast('?');
uint64_t mask5 = broadcast('[');
// This loop will get autovectorized under many optimizing compilers,
// so you get actually SIMD!
for (; i + 7 < view.size(); i += 8) {
uint64_t word{};
// performance: the next memcpy translates into a single CPU instruction.
memcpy(&word, view.data() + i, sizeof(word));
// performance: on little-endian systems (most systems), this next line is
// free.
word = swap_bytes_if_big_endian(word);
uint64_t xor1 = word ^ mask1;
uint64_t xor2 = word ^ mask2;
uint64_t xor3 = word ^ mask3;
uint64_t xor4 = word ^ mask4;
uint64_t xor5 = word ^ mask5;
uint64_t is_match = has_zero_byte(xor1) | has_zero_byte(xor2) |
has_zero_byte(xor3) | has_zero_byte(xor4) |
has_zero_byte(xor5);
if (is_match) {
return size_t(i + index_of_first_set_byte(is_match));
}
}
if (i < view.size()) {
uint64_t word{};
// performance: the next memcpy translates into a function call, but
// that is difficult to avoid. Might be a bit expensive.
memcpy(&word, view.data() + i, view.size() - i);
word = swap_bytes_if_big_endian(word);
uint64_t xor1 = word ^ mask1;
uint64_t xor2 = word ^ mask2;
uint64_t xor3 = word ^ mask3;
uint64_t xor4 = word ^ mask4;
uint64_t xor5 = word ^ mask5;
uint64_t is_match = has_zero_byte(xor1) | has_zero_byte(xor2) |
has_zero_byte(xor3) | has_zero_byte(xor4) |
has_zero_byte(xor5);
if (is_match) {
return size_t(i + index_of_first_set_byte(is_match));
auto const str = view.substr(location);
for (auto pos = str.begin(); pos != str.end(); ++pos) {
if (special_host_delimiters[(uint8_t)*pos]) {
return pos - str.begin() + location;
}
}
return view.size();
return size_t(view.size());
}

// starting at index location, this finds the next location of a character
// :, /, ? or [. If none is found, view.size() is returned.
// For use within get_host_delimiter_location.
ada_really_inline size_t find_next_host_delimiter(std::string_view view,
size_t location) noexcept {
// performance: if you plan to call find_next_host_delimiter more than once,
// you *really* want find_next_host_delimiter to be inlined, because
// otherwise, the constants may get reloaded each time (bad).
auto has_zero_byte = [](uint64_t v) {
return ((v - 0x0101010101010101) & ~(v)&0x8080808080808080);
};
auto index_of_first_set_byte = [](uint64_t v) {
return ((((v - 1) & 0x101010101010101) * 0x101010101010101) >> 56) - 1;
};
auto broadcast = [](uint8_t v) -> uint64_t {
return 0x101010101010101ull * v;
};
size_t i = location;
uint64_t mask1 = broadcast(':');
uint64_t mask2 = broadcast('/');
uint64_t mask4 = broadcast('?');
uint64_t mask5 = broadcast('[');
// This loop will get autovectorized under many optimizing compilers,
// so you get actually SIMD!
for (; i + 7 < view.size(); i += 8) {
uint64_t word{};
// performance: the next memcpy translates into a single CPU instruction.
memcpy(&word, view.data() + i, sizeof(word));
// performance: on little-endian systems (most systems), this next line is
// free.
word = swap_bytes_if_big_endian(word);
uint64_t xor1 = word ^ mask1;
uint64_t xor2 = word ^ mask2;
uint64_t xor4 = word ^ mask4;
uint64_t xor5 = word ^ mask5;
uint64_t is_match = has_zero_byte(xor1) | has_zero_byte(xor2) |
has_zero_byte(xor4) | has_zero_byte(xor5);
if (is_match) {
return size_t(i + index_of_first_set_byte(is_match));
auto const str = view.substr(location);
for (auto pos = str.begin(); pos != str.end(); ++pos) {
if (host_delimiters[(uint8_t)*pos]) {
return pos - str.begin() + location;
}
}
if (i < view.size()) {
uint64_t word{};
// performance: the next memcpy translates into a function call, but
// that is difficult to avoid. Might be a bit expensive.
memcpy(&word, view.data() + i, view.size() - i);
// performance: on little-endian systems (most systems), this next line is
// free.
word = swap_bytes_if_big_endian(word);
uint64_t xor1 = word ^ mask1;
uint64_t xor2 = word ^ mask2;
uint64_t xor4 = word ^ mask4;
uint64_t xor5 = word ^ mask5;
uint64_t is_match = has_zero_byte(xor1) | has_zero_byte(xor2) |
has_zero_byte(xor4) | has_zero_byte(xor5);
if (is_match) {
return size_t(i + index_of_first_set_byte(is_match));
}
}
return view.size();
return size_t(view.size());
}

ada_really_inline std::pair<size_t, bool> get_host_delimiter_location(
Expand Down