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zero out bytes beyond src_sz after loading src into the register

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Kovid Goyal 2024-01-10 14:45:42 +05:30
parent 645b2811e2
commit e9820eb207
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GPG key ID: 06BC317B515ACE7C
1 changed files with 50 additions and 6 deletions
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56
kitty/simd-string-impl.h
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@ -25,6 +25,7 @@ _Pragma("clang diagnostic pop")
#define integer_t CONCAT_EXPAND(CONCAT_EXPAND(simde__m, BITS), i)
#define shift_right_by_bytes128 simde_mm_srli_si128
#define count_trailing_zeros __builtin_ctz
#define zero_last_n_bytes FUNC(zero_last_n_bytes)
#if BITS == 128
#define set1_epi8(x) simde_mm_set1_epi8((char)(x))
@ -34,6 +35,7 @@ _Pragma("clang diagnostic pop")
#define store_aligned simde_mm_store_si128
#define cmpeq_epi8 simde_mm_cmpeq_epi8
#define cmplt_epi8 simde_mm_cmplt_epi8
#define cmpgt_epi8 simde_mm_cmpgt_epi8
#define or_si simde_mm_or_si128
#define and_si simde_mm_and_si128
#define andnot_si simde_mm_andnot_si128
@ -53,6 +55,7 @@ _Pragma("clang diagnostic pop")
#define shift_left_by_bits16 simde_mm_slli_epi16
#define shift_right_by_bits32 simde_mm_srli_epi32
#define shuffle_epi8 simde_mm_shuffle_epi8
#define numbered_bytes() set_epi8(15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)
// output[i] = MAX(0, a[i] - b[1i])
#define subtract_saturate_epu8 simde_mm_subs_epu8
#define create_zero_integer simde_mm_setzero_si128
@ -65,7 +68,8 @@ _Pragma("clang diagnostic pop")
#define load_unaligned simde_mm256_loadu_si256
#define store_aligned simde_mm256_store_si256
#define cmpeq_epi8 simde_mm256_cmpeq_epi8
#define cmplt_epi8(a, b) simde_mm256_cmpgt_epi8(b, a)
#define cmpgt_epi8 simde_mm256_cmpgt_epi8
#define cmplt_epi8(a, b) cmpgt_epi8(b, a)
#define or_si simde_mm256_or_si256
#define and_si simde_mm256_and_si256
#define andnot_si simde_mm256_andnot_si256
@ -86,6 +90,7 @@ _Pragma("clang diagnostic pop")
#define shift_left_by_four_bytes(vec) simde_mm256_alignr_epi8(vec, simde_mm256_permute2x128_si256(vec, vec, _MM_SHUFFLE(2, 0, 0, 1)), 4)
#define shift_left_by_eight_bytes(vec) simde_mm256_alignr_epi8(vec, simde_mm256_permute2x128_si256(vec, vec, _MM_SHUFFLE(2, 0, 0, 1)), 8)
#define shift_left_by_sixteen_bytes(vec) simde_mm256_permute2x128_si256(vec, vec, _MM_SHUFFLE(2, 0, 0, 1))
#define numbered_bytes() set_epi8(31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0)
static inline integer_t shuffle_impl256(const integer_t value, const integer_t shuffle) {
#define K0 simde_mm256_setr_epi8( \
@ -106,6 +111,13 @@ static inline integer_t shuffle_impl256(const integer_t value, const integer_t s
#define shuffle_epi8 shuffle_impl256
#endif
static inline integer_t
FUNC(zero_last_n_bytes)(integer_t vec, int n) {
const integer_t threshold = set1_epi8(n);
const integer_t index = numbered_bytes();
return andnot_si(cmpgt_epi8(threshold, index), vec);
}
static inline const uint8_t*
FUNC(find_either_of_two_bytes)(const uint8_t *haystack, const size_t sz, const uint8_t a, const uint8_t b) {
const integer_t a_vec = set1_epi8(a), b_vec = set1_epi8(b);
@ -171,12 +183,42 @@ FUNC(output_plain_ascii)(UTF8Decoder *d, integer_t vec, size_t src_sz) {
d->output_sz = src_sz;
}
#ifndef SIMD_STRING_IMPL_INCLUDED_ONCE
static void
scalar_decode_to_accept(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
while (d->num_consumed < src_sz && d->output_sz < arraysz(d->output) && d->state.cur != UTF8_ACCEPT) {
const uint8_t ch = src[d->num_consumed++];
switch(ch) {
case UTF8_ACCEPT:
d->output[d->output_sz++] = d->state.codep;
break;
case UTF8_REJECT: {
const bool prev_was_accept = d->state.prev == UTF8_ACCEPT;
zero_at_ptr(&d->state);
d->output[d->output_sz++] = 0xfffd;
if (!prev_was_accept && d->num_consumed) {
d->num_consumed--;
continue; // so that prev is correct
}
} break;
}
d->state.prev = d->state.cur;
}
}
#endif
static inline bool
FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
// Based on the algorithm described in: https://woboq.com/blog/utf-8-processing-using-simd.html
d->output_sz = 0; d->num_consumed = 0;
if (d->state.cur != UTF8_ACCEPT) {
scalar_decode_to_accept(d, src, src_sz);
src += d->num_consumed; src_sz -= d->num_consumed;
if (!src_sz) return false;
}
src_sz = MIN(src_sz, sizeof(integer_t));
integer_t vec = load_unaligned((integer_t*)src);
if (src_sz < sizeof(integer_t)/8) zero_last_n_bytes(vec, sizeof(integer_t)/8 - src_sz);
const integer_t esc_vec = set1_epi8(0x1b);
const integer_t esc_cmp = cmpeq_epi8(vec, esc_vec);
@ -292,11 +334,7 @@ FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
#endif
#undef move
// convert the shifts into a suitable mask for shuffle by adding the byte number to each byte
#if BITS == 128
shifts = add_epi8(shifts, set_epi8(15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0));
#else
shifts = add_epi8(shifts, set_epi8(31,30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0));
#endif
shifts = add_epi8(shifts, numbered_bytes());
print_register_as_bytes(shifts);
output1 = shuffle_epi8(output1, shifts);
@ -317,6 +355,7 @@ FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
#undef store_aligned
#undef cmpeq_epi8
#undef cmplt_epi8
#undef cmpgt_epi8
#undef or_si
#undef and_si
#undef andnot_si
@ -344,3 +383,8 @@ FUNC(utf8_decode_to_esc)(UTF8Decoder *d, const uint8_t *src, size_t src_sz) {
#undef subtract_saturate_epu8
#undef create_zero_integer
#undef shuffle_epi8
#undef numbered_bytes
#undef zero_last_n_bytes
#ifndef SIMD_STRING_IMPL_INCLUDED_ONCE
#define SIMD_STRING_IMPL_INCLUDED_ONCE
#endif