* Flatten ZSTD_row_getMatchMask
* Remove the SIMD abstraction layer.
* Add big endian support.
* Align `hashTags` within `tagRow` to a 16-byte boundary.
* Switch SSE2 to use aligned reads.
* Optimize scalar path using SWAR.
* Optimize neon path for `n == 32`
* Work around minor clang issue for NEON (https://bugs.llvm.org/show_bug.cgi?id=49577)
* replace memcpy with MEM_readST
* silence alignment warnings
* fix neon casts
* Update zstd_lazy.c
* unify simd preprocessor detection (#3)
* remove duplicate asserts
* tweak rotates
* improve endian detection
* add cast
there is a fun little catch-22 with gcc: result from pmovmskb has to be cast to uint32_t to avoid a zero-extension
but must be uint16_t to get gcc to generate a rotate instruction..
* more casts
* fix casts
better work-around for the (bogus) warning: unary minus on unsigned
This patch is supposed to improve compatibility with less featured tar variants
"when the tar program used does not support historical options (without hyphen) nor the '-z' option."
Patch proposed by Antonio Diaz Diaz
Compress the input twice in the `simple_round_trip` and
`dictionary_round_trip` fuzzers with exactly the same parameters, but
reusing the context. Then ensure that the compressed output is
identical.
Call `ZSTD_enforceMaxDist()` before each block with the beginning of the
block. This ensures that `lowLimit` is updated to `dictLimit` whenever
the ext-dict is out of range, so we can use prefix mode for speed.
This can cause non-determinism because prefix mode and ext-dict mode
match finders can return different results. It can also hurt speed
because ext-dict match finders are slower.
The scenario is:
1. Compress large data with a dictionary.
2. The dictionary goes out of bounds, so we invalidate it.
3. However, we still have `lowLimit < dictLimit`, since it is
never updated.
4. We will call the ext-dict match finder instead of the prefix one.
The repcode checks disallowed repcodes that are equal to `windowLow`.
This is slightly inefficient, but isn't a problem on its own. Together
with the next commit, it cause non-determinism.
`ZSTD_insertBt1()` has a speed optimization that skips the prefix of
very long matches.
40def70387/lib/compress/zstd_opt.c (L476)
This optimization is based off the length longest match found. However,
when indices are reset, we only ensure that we can reference the whole
window starting from `ip`. If the previous block ended with a long match
then `nextToUpdate` could be much less than `ip`. It might be far enough
back that `nextToUpdate < maxDist`, so it doesn't have a full window of
data to reference. This can cause non-determinism bugs, because we may
find a match that is beyond `ip - maxDist`, and may sometimes be
un-referencable, and that match triggers the speed optimization.
The fix is to base the `windowLow` off of the `target` of
`ZSTD_updateTree_internal()`, because anything below that value will be
obsolete by the time `ZSTD_updateTree_internal()` completes.
sen
Goutham Krishna
aqrit
Felix Handte
Yann Collet
Binh Vo
Nick Terrell
Yann Collet
Dan Nelson
TrianglesPCT
Bartosz Taudul