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Move finding byte code into separate functions

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movemask() is inefficient on ARM64 this will allow us to use a dedicated
implementation for finding bytes on that platform
This commit is contained in:
Kovid Goyal
2024-01-27 09:55:35 +05:30
parent 1d59bfade3
commit fcbda63023
1 changed files with 21 additions and 7 deletions
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28
kitty/simd-string-impl.h
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@@ -39,6 +39,7 @@ _Pragma("clang diagnostic pop")
#define shift_right_by_bytes128 simde_mm_srli_si128
#define zero_last_n_bytes FUNC(zero_last_n_bytes)
#define is_zero FUNC(is_zero)
typedef int32_t find_mask_t;
#if KITTY_SIMD_LEVEL == 128
#define set1_epi8(x) simde_mm_set1_epi8((char)(x))
@@ -78,6 +79,13 @@ _Pragma("clang diagnostic pop")
static inline int
FUNC(is_zero)(const integer_t a) { return simde_mm_testz_si128(a, a); }
static inline find_mask_t
mask_for_find(const integer_t a) { return movemask_epi8(a); }
static inline unsigned
bytes_to_first_match(const find_mask_t m) { return __builtin_ctz(m); }
#else
#define set1_epi8(x) simde_mm256_set1_epi8((char)(x))
@@ -105,6 +113,12 @@ FUNC(is_zero)(const integer_t a) { return simde_mm_testz_si128(a, a); }
static inline int
FUNC(is_zero)(const integer_t a) { return simde_mm256_testz_si256(a, a); }
static inline find_mask_t
mask_for_find(const integer_t a) { return movemask_epi8(a); }
static inline unsigned
bytes_to_first_match(const find_mask_t m) { return __builtin_ctz(m); }
static inline integer_t
shift_right_by_one_byte(const integer_t A) {
return simde_mm256_alignr_epi8(A, simde_mm256_permute2x128_si256(A, A, _MM_SHUFFLE(0, 0, 2, 0)), 16 - 1);
@@ -215,7 +229,7 @@ FUNC(find_either_of_two_bytes)(const uint8_t *haystack, const size_t sz, const u
const integer_t a_cmp = cmpeq_epi8(chunk, a_vec);
const integer_t b_cmp = cmpeq_epi8(chunk, b_vec);
const integer_t matches = or_si(a_cmp, b_cmp);
const int32_t mask = movemask_epi8(matches);
const find_mask_t mask = mask_for_find(matches);
if (mask != 0) {
const uint8_t *ans = haystack + __builtin_ctz(mask);
if (ans < limit) return ans;
@@ -370,7 +384,7 @@ FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
const integer_t esc_vec = set1_epi8(0x1b);
const integer_t esc_cmp = cmpeq_epi8(vec, esc_vec);
const int esc_test_mask = movemask_epi8(esc_cmp);
const find_mask_t esc_test_mask = mask_for_find(esc_cmp);
bool sentinel_found = false;
unsigned short num_of_bytes_to_first_esc;
if (esc_test_mask && (num_of_bytes_to_first_esc = __builtin_ctz(esc_test_mask)) < src_sz) {
@@ -390,9 +404,9 @@ FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
// Check if we have pure ASCII and use fast path
debug_register(vec);
int32_t ascii_mask;
find_mask_t ascii_mask;
start_classification:
ascii_mask = movemask_epi8(vec);
ascii_mask = mask_for_find(vec);
if (!ascii_mask) { // no bytes with high bit (0x80) set, so just plain ASCII
FUNC(output_plain_ascii)(d, vec, src_sz);
if (num_of_trailing_bytes) scalar_decode_all(d, src + src_sz, num_of_trailing_bytes);
@@ -425,7 +439,7 @@ start_classification:
// counts now contains the number of bytes remaining in each utf-8 sequence of 2 or more bytes
debug_register(counts);
// check for an incomplete trailing utf8 sequence
if (check_for_trailing_bytes && movemask_epi8(cmplt_epi8(one, and_si(counts, cmpeq_epi8(numbered_bytes(), set1_epi8(src_sz - 1)))))) {
if (check_for_trailing_bytes && mask_for_find(cmplt_epi8(one, and_si(counts, cmpeq_epi8(numbered_bytes(), set1_epi8(src_sz - 1)))))) {
// The value of counts at the last byte is > 1 indicating we have a trailing incomplete sequence
check_for_trailing_bytes = false;
if (src[src_sz-1] >= 0xc0) num_of_trailing_bytes = 1; // 2-, 3- and 4-byte characters with only 1 byte left
@@ -436,10 +450,10 @@ start_classification:
goto start_classification;
}
// Only ASCII chars should have corresponding byte of counts == 0
if (ascii_mask ^ movemask_epi8(cmpgt_epi8(counts, zero))) goto invalid_utf8;
if (ascii_mask != mask_for_find(cmpgt_epi8(counts, zero))) goto invalid_utf8;
// The difference between a byte in counts and the next one should be negative,
// zero, or one. Any other value means there is not enough continuation bytes.
if (movemask_epi8(cmpgt_epi8(subtract_epi8(shift_right_by_one_byte(counts), counts), one))) goto invalid_utf8;
if (mask_for_find(cmpgt_epi8(subtract_epi8(shift_right_by_one_byte(counts), counts), one))) goto invalid_utf8;
// Process the bytes storing the three resulting bytes that make up the unicode codepoint
// mask all control bits so that we have only useful bits left