From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- lib/zstd/common/bits.h | 150 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 lib/zstd/common/bits.h (limited to 'lib/zstd/common/bits.h') diff --git a/lib/zstd/common/bits.h b/lib/zstd/common/bits.h new file mode 100644 index 000000000..c5faaa3d7 --- /dev/null +++ b/lib/zstd/common/bits.h @@ -0,0 +1,150 @@ +/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */ +/* + * Copyright (c) Meta Platforms, Inc. and affiliates. + * All rights reserved. + * + * This source code is licensed under both the BSD-style license (found in the + * LICENSE file in the root directory of this source tree) and the GPLv2 (found + * in the COPYING file in the root directory of this source tree). + * You may select, at your option, one of the above-listed licenses. + */ + +#ifndef ZSTD_BITS_H +#define ZSTD_BITS_H + +#include "mem.h" + +MEM_STATIC unsigned ZSTD_countTrailingZeros32_fallback(U32 val) +{ + assert(val != 0); + { + static const U32 DeBruijnBytePos[32] = {0, 1, 28, 2, 29, 14, 24, 3, + 30, 22, 20, 15, 25, 17, 4, 8, + 31, 27, 13, 23, 21, 19, 16, 7, + 26, 12, 18, 6, 11, 5, 10, 9}; + return DeBruijnBytePos[((U32) ((val & -(S32) val) * 0x077CB531U)) >> 27]; + } +} + +MEM_STATIC unsigned ZSTD_countTrailingZeros32(U32 val) +{ + assert(val != 0); +#if (__GNUC__ >= 4) + return (unsigned)__builtin_ctz(val); +#else + return ZSTD_countTrailingZeros32_fallback(val); +#endif +} + +MEM_STATIC unsigned ZSTD_countLeadingZeros32_fallback(U32 val) +{ + assert(val != 0); + { + static const U32 DeBruijnClz[32] = {0, 9, 1, 10, 13, 21, 2, 29, + 11, 14, 16, 18, 22, 25, 3, 30, + 8, 12, 20, 28, 15, 17, 24, 7, + 19, 27, 23, 6, 26, 5, 4, 31}; + val |= val >> 1; + val |= val >> 2; + val |= val >> 4; + val |= val >> 8; + val |= val >> 16; + return 31 - DeBruijnClz[(val * 0x07C4ACDDU) >> 27]; + } +} + +MEM_STATIC unsigned ZSTD_countLeadingZeros32(U32 val) +{ + assert(val != 0); +#if (__GNUC__ >= 4) + return (unsigned)__builtin_clz(val); +#else + return ZSTD_countLeadingZeros32_fallback(val); +#endif +} + +MEM_STATIC unsigned ZSTD_countTrailingZeros64(U64 val) +{ + assert(val != 0); +#if (__GNUC__ >= 4) && defined(__LP64__) + return (unsigned)__builtin_ctzll(val); +#else + { + U32 mostSignificantWord = (U32)(val >> 32); + U32 leastSignificantWord = (U32)val; + if (leastSignificantWord == 0) { + return 32 + ZSTD_countTrailingZeros32(mostSignificantWord); + } else { + return ZSTD_countTrailingZeros32(leastSignificantWord); + } + } +#endif +} + +MEM_STATIC unsigned ZSTD_countLeadingZeros64(U64 val) +{ + assert(val != 0); +#if (__GNUC__ >= 4) + return (unsigned)(__builtin_clzll(val)); +#else + { + U32 mostSignificantWord = (U32)(val >> 32); + U32 leastSignificantWord = (U32)val; + if (mostSignificantWord == 0) { + return 32 + ZSTD_countLeadingZeros32(leastSignificantWord); + } else { + return ZSTD_countLeadingZeros32(mostSignificantWord); + } + } +#endif +} + +MEM_STATIC unsigned ZSTD_NbCommonBytes(size_t val) +{ + if (MEM_isLittleEndian()) { + if (MEM_64bits()) { + return ZSTD_countTrailingZeros64((U64)val) >> 3; + } else { + return ZSTD_countTrailingZeros32((U32)val) >> 3; + } + } else { /* Big Endian CPU */ + if (MEM_64bits()) { + return ZSTD_countLeadingZeros64((U64)val) >> 3; + } else { + return ZSTD_countLeadingZeros32((U32)val) >> 3; + } + } +} + +MEM_STATIC unsigned ZSTD_highbit32(U32 val) /* compress, dictBuilder, decodeCorpus */ +{ + assert(val != 0); + return 31 - ZSTD_countLeadingZeros32(val); +} + +/* ZSTD_rotateRight_*(): + * Rotates a bitfield to the right by "count" bits. + * https://en.wikipedia.org/w/index.php?title=Circular_shift&oldid=991635599#Implementing_circular_shifts + */ +MEM_STATIC +U64 ZSTD_rotateRight_U64(U64 const value, U32 count) { + assert(count < 64); + count &= 0x3F; /* for fickle pattern recognition */ + return (value >> count) | (U64)(value << ((0U - count) & 0x3F)); +} + +MEM_STATIC +U32 ZSTD_rotateRight_U32(U32 const value, U32 count) { + assert(count < 32); + count &= 0x1F; /* for fickle pattern recognition */ + return (value >> count) | (U32)(value << ((0U - count) & 0x1F)); +} + +MEM_STATIC +U16 ZSTD_rotateRight_U16(U16 const value, U32 count) { + assert(count < 16); + count &= 0x0F; /* for fickle pattern recognition */ + return (value >> count) | (U16)(value << ((0U - count) & 0x0F)); +} + +#endif /* ZSTD_BITS_H */ -- cgit v1.3.1