diff options
Diffstat (limited to 'absl/container')
-rw-r--r-- | absl/container/internal/raw_hash_set.cc | 5 | ||||
-rw-r--r-- | absl/container/internal/raw_hash_set.h | 35 |
2 files changed, 27 insertions, 13 deletions
diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc index 02301e19..efb3d6f3 100644 --- a/absl/container/internal/raw_hash_set.cc +++ b/absl/container/internal/raw_hash_set.cc @@ -104,10 +104,11 @@ bool CommonFieldsGenerationInfoEnabled::should_rehash_for_bug_detection_on_move( return ShouldRehashForBugDetection(ctrl, capacity); } -bool ShouldInsertBackwards(size_t hash, const ctrl_t* ctrl) { +bool ShouldInsertBackwardsForDebug(size_t capacity, size_t hash, + const ctrl_t* ctrl) { // To avoid problems with weak hashes and single bit tests, we use % 13. // TODO(kfm,sbenza): revisit after we do unconditional mixing - return (H1(hash, ctrl) ^ RandomSeed()) % 13 > 6; + return !is_small(capacity) && (H1(hash, ctrl) ^ RandomSeed()) % 13 > 6; } void ConvertDeletedToEmptyAndFullToDeleted(ctrl_t* ctrl, size_t capacity) { diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h index 07ff79af..514f21ae 100644 --- a/absl/container/internal/raw_hash_set.h +++ b/absl/container/internal/raw_hash_set.h @@ -546,7 +546,27 @@ inline bool IsEmptyGeneration(const GenerationType* generation) { // Mixes a randomly generated per-process seed with `hash` and `ctrl` to // randomize insertion order within groups. -bool ShouldInsertBackwards(size_t hash, const ctrl_t* ctrl); +bool ShouldInsertBackwardsForDebug(size_t capacity, size_t hash, + const ctrl_t* ctrl); + +// Returns insert position for the given mask. +// We want to add entropy even when ASLR is not enabled. +// In debug build we will randomly insert in either the front or back of +// the group. +// TODO(kfm,sbenza): revisit after we do unconditional mixing +template <class Mask> +ABSL_ATTRIBUTE_ALWAYS_INLINE inline auto GetInsertionOffset( + Mask mask, ABSL_ATTRIBUTE_UNUSED size_t capacity, + ABSL_ATTRIBUTE_UNUSED size_t hash, + ABSL_ATTRIBUTE_UNUSED const ctrl_t* ctrl) { +#if defined(NDEBUG) + return mask.LowestBitSet(); +#else + return ShouldInsertBackwardsForDebug(capacity, hash, ctrl) + ? mask.HighestBitSet() + : mask.LowestBitSet(); +#endif +} // Returns a per-table, hash salt, which changes on resize. This gets mixed into // H1 to randomize iteration order per-table. @@ -1495,16 +1515,9 @@ inline FindInfo find_first_non_full(const CommonFields& common, size_t hash) { GroupFullEmptyOrDeleted g{ctrl + seq.offset()}; auto mask = g.MaskEmptyOrDeleted(); if (mask) { -#if !defined(NDEBUG) - // We want to add entropy even when ASLR is not enabled. - // In debug build we will randomly insert in either the front or back of - // the group. - // TODO(kfm,sbenza): revisit after we do unconditional mixing - if (!is_small(common.capacity()) && ShouldInsertBackwards(hash, ctrl)) { - return {seq.offset(mask.HighestBitSet()), seq.index()}; - } -#endif - return {seq.offset(mask.LowestBitSet()), seq.index()}; + return { + seq.offset(GetInsertionOffset(mask, common.capacity(), hash, ctrl)), + seq.index()}; } seq.next(); assert(seq.index() <= common.capacity() && "full table!"); |