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added compilation-time checks to ensure AVX2 code is valid

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since it depends on a specific definition of ZSTD_Sequence structure.
This commit is contained in:
Yann Collet
2025-01-15 17:11:27 -08:00
committed by Yann Collet
parent 57a4554192
commit aa2cdf964f
1 changed files with 13 additions and 0 deletions
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lib/compress/zstd_compress.c
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@@ -7176,6 +7176,17 @@ size_t convertSequences_noRepcodes(
#define PERM_LANE_0X_E8 0xE8 /* [0,2,2,3] in lane indices */
size_t longLen = 0, i = 0;
/* AVX permutation depends on the specific definition of target structures */
ZSTD_STATIC_ASSERT(sizeof(ZSTD_Sequence) == 16);
ZSTD_STATIC_ASSERT(offsetof(ZSTD_Sequence, offset) == 0);
ZSTD_STATIC_ASSERT(offsetof(ZSTD_Sequence, litLength) == 4);
ZSTD_STATIC_ASSERT(offsetof(ZSTD_Sequence, matchLength) == 8);
ZSTD_STATIC_ASSERT(sizeof(SeqDef) == 8);
ZSTD_STATIC_ASSERT(offsetof(SeqDef, offBase) == 0);
ZSTD_STATIC_ASSERT(offsetof(SeqDef, litLength) == 4);
ZSTD_STATIC_ASSERT(offsetof(SeqDef, mlBase) == 6);
/* Process 2 sequences per loop iteration */
for (; i + 1 < nbSequences; i += 2) {
/* Load 2 ZSTD_Sequence (32 bytes) */
@@ -7398,6 +7409,7 @@ BlockSummary ZSTD_get1BlockSummary(const ZSTD_Sequence* seqs, size_t nbSeqs)
__m256i sumVec = zeroVec; /* accumulates match+lit in 32-bit lanes */
ALIGNED32 U32 tmp[8]; /* temporary buffer for reduction */
size_t mSum = 0, lSum = 0;
ZSTD_STATIC_ASSERT(sizeof(ZSTD_Sequence) == 16);
/* Process 2 structs (32 bytes) at a time */
for (i = 0; i + 2 <= nbSeqs; i += 2) {
@@ -7408,6 +7420,7 @@ BlockSummary ZSTD_get1BlockSummary(const ZSTD_Sequence* seqs, size_t nbSeqs)
int cmp_res = _mm256_movemask_epi8(cmp);
/* indices for match lengths correspond to bits [8..11], [24..27]
* => combined mask = 0x0F000F00 */
ZSTD_STATIC_ASSERT(offsetof(ZSTD_Sequence, matchLength) == 8);
if (cmp_res & 0x0F000F00) break;
/* Accumulate in sumVec */
sumVec = _mm256_add_epi32(sumVec, data);