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Use simd in a few loops

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Kovid Goyal
2023-11-10 11:53:36 +05:30
parent 89d416806b
commit e3d6aa2c60
2 changed files with 41 additions and 5 deletions
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42
kitty/simd-string.c
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@@ -61,9 +61,9 @@ byte_loader_skip(ByteLoader *self) {
#define prepare_for_hasvalue(n) (~0ULL/255 * (n))
#define hasvalue(x,n) (haszero((x) ^ (n)))
static uint8_t*
find_either_of_two_chars_simple(uint8_t *haystack, const size_t sz, const uint8_t x, const uint8_t y) {
ByteLoader it; byte_loader_init(&it, haystack, sz);
static const char*
find_either_of_two_bytes_simple(const char *haystack, const size_t sz, const uint8_t x, const uint8_t y) {
ByteLoader it; byte_loader_init(&it, (uint8_t*)haystack, sz);
// first align by testing the first few bytes one at a time
while (it.num_left && it.digits_left < sizeof(BYTE_LOADER_T)) {
@@ -74,7 +74,7 @@ find_either_of_two_chars_simple(uint8_t *haystack, const size_t sz, const uint8_
const BYTE_LOADER_T a = prepare_for_hasvalue(x), b = prepare_for_hasvalue(y);
while (it.num_left) {
if (hasvalue(it.m, a) || hasvalue(it.m, b)) {
uint8_t *ans = haystack + sz - it.num_left, q = hasvalue(it.m, a) ? x : y;
const char *ans = haystack + sz - it.num_left, q = hasvalue(it.m, a) ? x : y;
while (it.num_left) {
if (byte_loader_next(&it) == q) return ans;
ans++;
@@ -87,7 +87,39 @@ find_either_of_two_chars_simple(uint8_t *haystack, const size_t sz, const uint8_
}
#undef SHIFT_OP
static const char*
find_either_of_two_bytes_simd_impl(const char *haystack, const char* needle_, size_t sz) {
size_t extra = (uintptr_t)haystack % sizeof(__m128i);
if (extra) { // need aligned loads for performance so search first few bytes by hand
const char *ans = find_either_of_two_bytes_simple(haystack, MIN(sz, extra), needle_[0], needle_[1]);
if (ans) return ans;
extra = MIN(extra, sz);
sz -= extra;
haystack += extra;
if (!sz) return NULL;
}
const __m128i needle = _mm_load_si128((const __m128i *)needle_);
for (const char* limit = haystack + sz; haystack < limit; haystack += 16) {
const __m128i h = _mm_load_si128((const __m128i *)haystack);
int c = _mm_cmpistri(needle, h, _SIDD_CMP_EQUAL_ANY);
if (c != 16) {
return haystack + c;
}
}
return NULL;
}
static uint8_t*
find_either_of_two_bytes_simd(uint8_t *haystack, const size_t sz, const uint8_t x, const uint8_t y) {
uint8_t before = haystack[sz];
haystack[sz] = 0;
char needle[16] = {x, y, 0,0,0,0,0,0,0,0,0,0,0,0,0,0};
uint8_t *ans = (uint8_t*)find_either_of_two_bytes_simd_impl((char*)haystack, needle, sz);
haystack[sz] = before;
return ans;
}
uint8_t*
find_either_of_two_bytes(uint8_t *haystack, const size_t sz, const uint8_t a, const uint8_t b) {
return find_either_of_two_chars_simple(haystack, sz, a, b);
return find_either_of_two_bytes_simd(haystack, sz, a, b);
}

4
kitty/simd-string.h
View File

@@ -20,4 +20,8 @@ typedef struct ByteLoader {
uint8_t byte_loader_peek(const ByteLoader *self);
void byte_loader_init(ByteLoader *self, const uint8_t *buf, unsigned int sz);
uint8_t byte_loader_next(ByteLoader *self);
// Requires haystack[sz] to be writable and 7 bytes to the left of haystack to
// be readable. Returns pointer to first position in haystack that contains
// either of the two chars or NULL if not found.
uint8_t* find_either_of_two_bytes(uint8_t *haystack, const size_t sz, const uint8_t a, const uint8_t b);