From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B2E9C04E84 for ; Thu, 16 May 2019 01:47:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1CBE20881 for ; Thu, 16 May 2019 01:47:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727916AbfEPBr1 (ORCPT ); Wed, 15 May 2019 21:47:27 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:45138 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726157AbfEPBgy (ORCPT ); Wed, 15 May 2019 21:36:54 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 9E8C33DE57BB92C7E863; Thu, 16 May 2019 09:36:50 +0800 (CST) Received: from [10.151.23.176] (10.151.23.176) by smtp.huawei.com (10.3.19.202) with Microsoft SMTP Server (TLS) id 14.3.439.0; Thu, 16 May 2019 09:36:43 +0800 Subject: Re: [PATCH 1/1] LZ4: Port LZ4 1.9.x FAST_DEC_LOOP and enable it on x86 and ARM64 To: "Mao, Chenxi" CC: Cyan , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "Feng, Roy" , "Xu, Yuanli 2" , "Alm, Robert 2" , "Takahashi, Masaya A (Sony Mobile)" , Miao Xie , Greg Kroah-Hartman References: <20190515004336.66555-1-chenxi.mao@sony.com> <649ba9ed-223e-1e82-1513-f3c16e4c8f9a@huawei.com> <0c1d0d7d24ae48f68ae6acc95c0c4869@CNBJMBX12.corpusers.net> <5c735ce9-04fc-a2a4-4f0c-ba5718fe7933@sony.com> From: Gao Xiang Message-ID: <1ca01dfb-c478-0752-cda0-b98f3da9f1b0@huawei.com> Date: Thu, 16 May 2019 09:35:38 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <5c735ce9-04fc-a2a4-4f0c-ba5718fe7933@sony.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.151.23.176] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/5/16 7:48, Mao, Chenxi wrote: > Hi Yann and Xiang: > For this FAST_DEC_LOOP change, I only pick up decompress related patches to current kernel LZ4 implementation(based on 1.8.3). > Here is my cherry-pick list: > 2589c44 created LZ4_FAST_DEC_LOOP build macro > 605d811 enable LZ4_FAST_DEC_LOOP build macro on aarch64/GCC by default > 5d7d116 decompress_generic: Limit fastpath to x86 > 75fb878 decompress_generic: Add fastpath for small offsets > faac110 decompress_generic: Unroll loops a bit more > 1fbaf84 decompress_generic: remove msan write > 28b8249 decompress_generic: re-add fastpath > 232f1e2 decompress_generic: drop partial copy check in fast loop > 59332a3 decompress_generic: Optimize literal copies > 5dfa7d4 decompress_generic: optimize match copy > 28356e0 decompress_generic: Add a loop fastpath > 4da3360 decompress_generic: Refactor variable length fields > > Only cherry-pick these changes to LZ4 1.8.3 would not be introduce risks. The fact is that ... LZ4_FAST_DEC_LOOP almost influences all decompression apis. You should keep LZ4_decompress_generic from all known issues. > > @Xiang: > Do you prefer to upgrade kernel lz4 to 1.9.1 directly or only pick some optimization patches? I think you should pick all patches which are related to LZ4_decompress_generic() and LZ4_FAST_DEC_LOOP since known issues of LZ4_FAST_DEC_LOOP should be fixed of course. Thanks, Gao Xiang > > Chenxi > > > On 5/16/19 1:47 AM, Gao Xiang wrote: >> Hi Yann, >> >> On 2019/5/16 1:03, Cyan wrote: >>> Re-posted, >>> it seems the previous message was rejected by the linux-kernel server >>> due to some kind of format limitation (no html). >>> >>> >>> Le mer. 15 mai 2019 à 09:56, Cyan a écrit : >>>> >>>> The v1.9.0 version has a bug which makes it read a few bytes out of bound in certain cases. >>>> This was fixed in v1.9.1. >>>> Therefore, if you plan upgrading version, skip directly to v1.9.1. >>>> >>>> Note that, in v1.9.1, LZ4_decompress_fast() is now deprecated. >>>> LZ4_decompress_fast() is a security liability, since it's unable to cope with malicious inputs. >>>> While this is not a problem when the producer is under direct control (local production and consumption, no intermediate storage), >>>> this entry point seems misused in multiple scenarios where input cannot be decently trusted. >>>> The deprecation warning is meant to "scare away" such usages. >>>> It's still possible to intentionally remove the warning, for users who know what they are doing. >>>> >>>> Note that, on top of that, the _fast() variant is now slower that LZ4_decompress_safe(), removing its most important positive differentiator. >>>> That's because LZ4_decompress_fast() is "blind", it doesn't know the input size. >>>> It just guesses it, from the requested output size, and by relying on end-of-block conditions. >>>> This effectively limits its capability to copy up to 8 bytes at a time, >>>> which proves slower than the 32-bytes at a time used in LZ4_decompress_safe(). >>>> >>>> LZ4_decompress_fast() still has some possible usage : >>>> it doesn't need the compressed size. >>>> Therefore, in a scenario where decompressed size is known, but compressed size isn't, >>>> it cannot be replaced by `LZ4_decompress_safe()`. >>>> This is pretty rare, but can happen in some cases, erofs for example. >>>> `LZ4_decompress_safe_partial()` *might* be able to replace it for such scenario, >>>> but I haven't thoroughly tested it, so can't yet vouch for it. >> >> Yes, that is my real concern... >> >> In fact, we have shipped erofs with LZ4_decompress_safe_partial() of lz4-1.8.3 >> for our HUAWEI P30/P30 Pro and other HUAWEI EMUI 9.1 phones on the market... >> >> It seemd lz4-1.8.3 is rather stable since no stability report from our internal >> beta test and real consumers... >> >> I haven't tested lz4-1.9.0 yet since I am working on the erofs paper [1]... >> >> But anyway, the patch looks good to me since it has obvious performance gain... >> >>>> >>>> If it doesn't, then it will be necessary to create a new entry point. >>>> The main difference is that this new entry point will need a bound for the input size, in order to guarantee it never reads beyond input buffer. >>>> But as said, for the time being, such dedicated entry point doesn't exist. >> >> I agree, but current erofs still have to choose LZ4_decompress_fast... >> I will test these 2 apis later and will report if something is wrong as well. >> >> [1] https://www.usenix.org/conference/atc19/presentation/gao >> https://www.usenix.org/conference/atc19/technical-sessions >> >> Thanks, >> Gao Xiang >> >> >>>> >>>> The new FAST_DEC_LOOP setting works well on x86 and x64. >>>> Recently, it has been extended to gcc+arm64 (`dev` branch). >>>> The combination of clang+arm64 is less successful though (impacts vary, depending on version and exact hardware), so it's still disabled by default. >>>> But anyone can test it by setting FAST_DEC_LOOP definition to 1, thus enabling the new decoder loop. >>>> >>>> >>>> Y. >>>> >>>> Le mar. 14 mai 2019 à 20:28, Mao, Chenxi a écrit : >>>>> >>>>> Hi Xiang: >>>>> >>>>> Thanks for your reply, I will have a stress test on my device later. >>>>> I didn't have chance to test LZ4 with clang build because of device limitation. I think I could do it later. >>>>> I guess the clang performance downgrade is caused by some compiler optimization options. >>>>> I will double check it later if I got the device which can build kernel with clang. >>>>> >>>>> BTW, the FAST_DEC_LOOP leverage LZ4_wildCopy8 instead of LZ4_wildCopy, >>>>> however based on my test, original LZ4_wildCopy has the better performance. >>>>> Original LZ4_wildCopy API still invoked by FAST_DEC_LOOP apis. >>>>> That might be a problem for X86 devices for current patch. >>>>> >>>>> Chenxi >>>>> >>>>> -----Original Message----- >>>>> From: Gao Xiang [mailto:gaoxiang25@huawei.com] >>>>> Sent: Wednesday, May 15, 2019 10:21 AM >>>>> To: Mao, Chenxi >>>>> Cc: akpm@linux-foundation.org; linux-kernel@vger.kernel.org; Feng, Roy ; Xu, Yuanli 2 ; Alm, Robert 2 ; Takahashi, Masaya A (Sony Mobile) ; Miao Xie >>>>> Subject: Re: [PATCH 1/1] LZ4: Port LZ4 1.9.x FAST_DEC_LOOP and enable it on x86 and ARM64 >>>>> >>>>> Hi Chenxi, >>>>> >>>>> On 2019/5/15 8:43, Chenxi Mao wrote: >>>>>> FAST_DEC_LOOP was introduced from LZ4 1.9. >>>>>> This change would be introduce 10% on decompress operation according >>>>>> to LZ4 benchmark result on X86 devices. >>>>>> Meanwhile, LZ4 with FAST_DEC_LOOP could get improvements, however >>>>>> clang compiler has downgrade if FAST_DEC_LOOP enabled. >>>>> >>>>> I noticed this optimization and lz4-1.9.0 [1] was just released month ago with this big change therefore I'm a little afraid of its current stability (especially some rare used decompression apis...) >>>>> >>>>> Could you Cc more people (e.g. lz4 original author Yann Collet) in order to get some more ideas about this if possible? >>>>> >>>>> Anyway, I like this optimization as well since FAST_DEC_LOOP improves decompression speed a lot :) >>>>> >>>>> [1] https://github.com/lz4/lz4/releases/tag/v1.9.0 >>>>> >>>>> Thanks, >>>>> Gao Xiang >>>>> >>>>>> >>>>>> So FAST_DEC_LOOP only enabled on X86/X86-64 or ARM64 with GCC build. >>>>>> >>>>>> Here is the test result on ARM64(cortex-A53) >>>>>> >>>>>> Benchmark via ZRAM: >>>>>> >>>>>> Test case: >>>>>> fio --bs=32k --randrepeat=1 --randseed=100 --refill_buffers \ >>>>>> --buffer_compress_percentage=75 \ >>>>>> --scramble_buffers=1 --direct=1 --loops=100 --numjobs=8 \ >>>>>> --filename=/dev/block/zram0 --name=seq-write --rw=write --stonewall \ >>>>>> --name=seq-read --rw=read --stonewall --name=seq-readwrite \ --rw=rw >>>>>> --stonewall --name=rand-readwrite --rw=randrw --stonewall >>>>>> >>>>>> Patched: >>>>>> READ: bw=7077MiB/s (7421MB/s) >>>>>> Vanilla: >>>>>> READ: bw=5134MiB/s (5384MB/s) >>>>>> >>>>>> Reference: >>>>>> 1. https://github.com/lz4/lz4/pull/645 >>>>>> 2. https://github.com/lz4/lz4/pull/707 >>>>>> >>>>>> Signed-off-by: chenxi.mao >>>>>> --- >>>>>> lib/lz4/lz4_decompress.c | 425 >>>>>> +++++++++++++++++++++++++++++++++------ >>>>>> 1 file changed, 361 insertions(+), 64 deletions(-) >>>>>> >>>>>> diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index >>>>>> 0c9d3ad17e0f..a4c87e32b3c0 100644 >>>>>> --- a/lib/lz4/lz4_decompress.c >>>>>> +++ b/lib/lz4/lz4_decompress.c >>>>>> @@ -50,6 +50,131 @@ >>>>>> #define assert(condition) ((void)0) >>>>>> #endif >>>>>> >>>>>> +#ifndef LZ4_FAST_DEC_LOOP >>>>>> +#if defined(__i386__) || defined(__x86_64__) #define >>>>>> +LZ4_FAST_DEC_LOOP 1 #elif defined(__aarch64__) && !defined(__clang__) >>>>>> + /* On aarch64, we disable this optimization for clang because on certain >>>>>> + * mobile chipsets and clang, it reduces performance. For more information >>>>>> + * refer to https://github.com/lz4/lz4/pull/707. */ #define >>>>>> +LZ4_FAST_DEC_LOOP 1 #else #define LZ4_FAST_DEC_LOOP 0 #endif #endif >>>>>> + >>>>>> +static const unsigned inc32table[8] = { 0, 1, 2, 1, 0, 4, 4, 4 }; >>>>>> +static const int dec64table[8] = { 0, 0, 0, -1, -4, 1, 2, 3 }; >>>>>> + >>>>>> +#if LZ4_FAST_DEC_LOOP >>>>>> +#define FASTLOOP_SAFE_DISTANCE 64 >>>>>> +FORCE_INLINE void >>>>>> +LZ4_memcpy_using_offset_base(BYTE * dstPtr, const BYTE * srcPtr, BYTE * dstEnd, >>>>>> + const size_t offset) >>>>>> +{ >>>>>> + if (offset < 8) { >>>>>> + dstPtr[0] = srcPtr[0]; >>>>>> + >>>>>> + dstPtr[1] = srcPtr[1]; >>>>>> + dstPtr[2] = srcPtr[2]; >>>>>> + dstPtr[3] = srcPtr[3]; >>>>>> + srcPtr += inc32table[offset]; >>>>>> + memcpy(dstPtr + 4, srcPtr, 4); >>>>>> + srcPtr -= dec64table[offset]; >>>>>> + dstPtr += 8; >>>>>> + } else { >>>>>> + memcpy(dstPtr, srcPtr, 8); >>>>>> + dstPtr += 8; >>>>>> + srcPtr += 8; >>>>>> + } >>>>>> + >>>>>> + LZ4_wildCopy(dstPtr, srcPtr, dstEnd); } >>>>>> + >>>>>> +/* customized variant of memcpy, which can overwrite up to 32 bytes >>>>>> +beyond dstEnd >>>>>> + * this version copies two times 16 bytes (instead of one time 32 >>>>>> +bytes) >>>>>> + * because it must be compatible with offsets >= 16. */ FORCE_INLINE >>>>>> +void LZ4_wildCopy32(void *dstPtr, const void *srcPtr, void *dstEnd) { >>>>>> + BYTE *d = (BYTE *) dstPtr; >>>>>> + const BYTE *s = (const BYTE *)srcPtr; >>>>>> + BYTE *const e = (BYTE *) dstEnd; >>>>>> + >>>>>> + do { >>>>>> + memcpy(d, s, 16); >>>>>> + memcpy(d + 16, s + 16, 16); >>>>>> + d += 32; >>>>>> + s += 32; >>>>>> + } while (d < e); >>>>>> +} >>>>>> + >>>>>> +FORCE_INLINE void >>>>>> +LZ4_memcpy_using_offset(BYTE *dstPtr, const BYTE *srcPtr, BYTE *dstEnd, >>>>>> + const size_t offset) >>>>>> +{ >>>>>> + BYTE v[8]; >>>>>> + switch (offset) { >>>>>> + >>>>>> + case 1: >>>>>> + memset(v, *srcPtr, 8); >>>>>> + goto copy_loop; >>>>>> + case 2: >>>>>> + memcpy(v, srcPtr, 2); >>>>>> + memcpy(&v[2], srcPtr, 2); >>>>>> + memcpy(&v[4], &v[0], 4); >>>>>> + goto copy_loop; >>>>>> + case 4: >>>>>> + memcpy(v, srcPtr, 4); >>>>>> + memcpy(&v[4], srcPtr, 4); >>>>>> + goto copy_loop; >>>>>> + default: >>>>>> + LZ4_memcpy_using_offset_base(dstPtr, srcPtr, dstEnd, offset); >>>>>> + return; >>>>>> + } >>>>>> + >>>>>> + copy_loop: >>>>>> + memcpy(dstPtr, v, 8); >>>>>> + dstPtr += 8; >>>>>> + while (dstPtr < dstEnd) { >>>>>> + memcpy(dstPtr, v, 8); >>>>>> + dstPtr += 8; >>>>>> + } >>>>>> +} >>>>>> + >>>>>> +/* Read the variable-length literal or match length. >>>>>> + * >>>>>> + * ip - pointer to use as input. >>>>>> + * lencheck - end ip. Return an error if ip advances >= lencheck. >>>>>> + * loop_check - check ip >= lencheck in body of loop. Returns loop_error if so. >>>>>> + * initial_check - check ip >= lencheck before start of loop. Returns initial_error if so. >>>>>> + * error (output) - error code. Should be set to 0 before call. >>>>>> + */ >>>>>> +typedef enum { loop_error = -2, initial_error = -1, ok = 0} >>>>>> +variable_length_error; FORCE_INLINE unsigned read_variable_length(const BYTE **ip, >>>>>> + const BYTE *lencheck, >>>>>> + int loop_check, int initial_check, >>>>>> + variable_length_error *error) { >>>>>> + unsigned length = 0; >>>>>> + unsigned s; >>>>>> + if (initial_check && unlikely((*ip) >= lencheck)) { /* overflow detection */ >>>>>> + *error = initial_error; >>>>>> + return length; >>>>>> + } >>>>>> + do { >>>>>> + s = **ip; >>>>>> + (*ip)++; >>>>>> + length += s; >>>>>> + if (loop_check && unlikely((*ip) >= lencheck)) { /* overflow detection */ >>>>>> + *error = loop_error; >>>>>> + return length; >>>>>> + } >>>>>> + } while (s == 255); >>>>>> + >>>>>> + return length; >>>>>> +} >>>>>> +#endif >>>>>> + >>>>>> /* >>>>>> * LZ4_decompress_generic() : >>>>>> * This generic decompression function covers all use cases. >>>>>> @@ -80,25 +205,28 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> const size_t dictSize >>>>>> ) >>>>>> { >>>>>> - const BYTE *ip = (const BYTE *) src; >>>>>> - const BYTE * const iend = ip + srcSize; >>>>>> + const BYTE *ip = (const BYTE *)src; >>>>>> + const BYTE *const iend = ip + srcSize; >>>>>> >>>>>> BYTE *op = (BYTE *) dst; >>>>>> - BYTE * const oend = op + outputSize; >>>>>> + BYTE *const oend = op + outputSize; >>>>>> BYTE *cpy; >>>>>> >>>>>> - const BYTE * const dictEnd = (const BYTE *)dictStart + dictSize; >>>>>> - static const unsigned int inc32table[8] = {0, 1, 2, 1, 0, 4, 4, 4}; >>>>>> - static const int dec64table[8] = {0, 0, 0, -1, -4, 1, 2, 3}; >>>>>> + const BYTE *const dictEnd = (const BYTE *)dictStart + dictSize; >>>>>> >>>>>> const int safeDecode = (endOnInput == endOnInputSize); >>>>>> const int checkOffset = ((safeDecode) && (dictSize < (int)(64 * >>>>>> KB))); >>>>>> >>>>>> /* Set up the "end" pointers for the shortcut. */ >>>>>> const BYTE *const shortiend = iend - >>>>>> - (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/; >>>>>> + (endOnInput ? 14 : 8) /*maxLL*/ - 2 /*offset*/; >>>>>> const BYTE *const shortoend = oend - >>>>>> - (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/; >>>>>> + (endOnInput ? 14 : 8) /*maxLL*/ - 18 /*maxML*/; >>>>>> + >>>>>> + const BYTE *match; >>>>>> + size_t offset; >>>>>> + unsigned int token; >>>>>> + size_t length; >>>>>> >>>>>> DEBUGLOG(5, "%s (srcSize:%i, dstSize:%i)", __func__, >>>>>> srcSize, outputSize); >>>>>> @@ -117,15 +245,194 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> if ((endOnInput) && unlikely(srcSize == 0)) >>>>>> return -1; >>>>>> >>>>>> - /* Main Loop : decode sequences */ >>>>>> +#if LZ4_FAST_DEC_LOOP >>>>>> + if ((oend - op) < FASTLOOP_SAFE_DISTANCE) { >>>>>> + DEBUGLOG(6, "skip fast decode loop"); >>>>>> + goto safe_decode; >>>>>> + } >>>>>> + >>>>>> + /* Fast loop : decode sequences as long as output < >>>>>> +iend-FASTLOOP_SAFE_DISTANCE */ >>>>>> while (1) { >>>>>> - size_t length; >>>>>> - const BYTE *match; >>>>>> - size_t offset; >>>>>> + /* Main fastloop assertion: We can always wildcopy FASTLOOP_SAFE_DISTANCE */ >>>>>> + assert(oend - op >= FASTLOOP_SAFE_DISTANCE); >>>>>> + if (endOnInput) { >>>>>> + assert(ip < iend); >>>>>> + } >>>>>> + token = *ip++; >>>>>> + length = token >> ML_BITS; /* literal length */ >>>>>> + >>>>>> + assert(!endOnInput || ip <= iend); /* ip < iend before the increment */ >>>>>> + >>>>>> + /* decode literal length */ >>>>>> + if (length == RUN_MASK) { >>>>>> + variable_length_error error = ok; >>>>>> + length += >>>>>> + read_variable_length(&ip, iend - RUN_MASK, >>>>>> + endOnInput, endOnInput, >>>>>> + &error); >>>>>> + if (error == initial_error) { >>>>>> + goto _output_error; >>>>>> + } >>>>>> + if ((safeDecode) >>>>>> + && unlikely((uptrval) (op) + length < >>>>>> + (uptrval) (op))) { >>>>>> + goto _output_error; >>>>>> + } /* overflow detection */ >>>>>> + if ((safeDecode) >>>>>> + && unlikely((uptrval) (ip) + length < >>>>>> + (uptrval) (ip))) { >>>>>> + goto _output_error; >>>>>> + } >>>>>> + >>>>>> + /* overflow detection */ >>>>>> + /* copy literals */ >>>>>> + cpy = op + length; >>>>>> + LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH); >>>>>> + if (endOnInput) { /* LZ4_decompress_safe() */ >>>>>> + if ((cpy > oend - 32) >>>>>> + || (ip + length > iend - 32)) { >>>>>> + goto safe_literal_copy; >>>>>> + } >>>>>> + LZ4_wildCopy32(op, ip, cpy); >>>>>> + } else { /* LZ4_decompress_fast() */ >>>>>> + if (cpy > oend - 8) { >>>>>> + goto safe_literal_copy; >>>>>> + } >>>>>> + LZ4_wildCopy(op, ip, cpy); >>>>>> + /* LZ4_decompress_fast() cannot copy more than 8 bytes at a time */ >>>>>> + /* it doesn't know input length, and only relies on end-of-block */ >>>>>> + /* properties */ >>>>>> + } >>>>>> + ip += length; >>>>>> + op = cpy; >>>>>> + } else { >>>>>> + cpy = op + length; >>>>>> + if (endOnInput) { /* LZ4_decompress_safe() */ >>>>>> + DEBUGLOG(7, >>>>>> + "copy %u bytes in a 16-bytes stripe", >>>>>> + (unsigned)length); >>>>>> + /* We don't need to check oend */ >>>>>> + /* since we check it once for each loop below */ >>>>>> + if (ip > iend - (16 + 1)) { /*max lit + offset + nextToken */ >>>>>> + goto safe_literal_copy; >>>>>> + } >>>>>> + /* Literals can only be 14, but hope compilers optimize */ >>>>>> + /*if we copy by a register size */ >>>>>> + memcpy(op, ip, 16); >>>>>> + } else { >>>>>> + /* LZ4_decompress_fast() cannot copy more than 8 bytes at a time */ >>>>>> + /* it doesn't know input length, and relies on end-of-block */ >>>>>> + /* properties */ >>>>>> + memcpy(op, ip, 8); >>>>>> + if (length > 8) { >>>>>> + memcpy(op + 8, ip + 8, 8); >>>>>> + } >>>>>> + } >>>>>> + ip += length; >>>>>> + op = cpy; >>>>>> + } >>>>>> + >>>>>> + /* get offset */ >>>>>> + offset = LZ4_readLE16(ip); >>>>>> + ip += 2; /* end-of-block condition violated */ >>>>>> + match = op - offset; >>>>>> + >>>>>> + /* get matchlength */ >>>>>> + length = token & ML_MASK; >>>>>> >>>>>> - /* get literal length */ >>>>>> - unsigned int const token = *ip++; >>>>>> - length = token>>ML_BITS; >>>>>> + if ((checkOffset) && (unlikely(match + dictSize < lowPrefix))) { >>>>>> + goto _output_error; >>>>>> + } >>>>>> + /* Error : offset outside buffers */ >>>>>> + if (length == ML_MASK) { >>>>>> + variable_length_error error = ok; >>>>>> + length += >>>>>> + read_variable_length(&ip, iend - LASTLITERALS + 1, >>>>>> + endOnInput, 0, &error); >>>>>> + if (error != ok) { >>>>>> + goto _output_error; >>>>>> + } >>>>>> + if ((safeDecode) >>>>>> + && unlikely((uptrval) (op) + length < (uptrval) op)) { >>>>>> + goto _output_error; >>>>>> + } /* overflow detection */ >>>>>> + length += MINMATCH; >>>>>> + if (op + length >= oend - FASTLOOP_SAFE_DISTANCE) { >>>>>> + goto safe_match_copy; >>>>>> + } >>>>>> + } else { >>>>>> + length += MINMATCH; >>>>>> + if (op + length >= oend - FASTLOOP_SAFE_DISTANCE) { >>>>>> + goto safe_match_copy; >>>>>> + } >>>>>> + >>>>>> + /* Fastpath check: Avoids a branch in LZ4_wildCopy32 if true */ >>>>>> + if (!(dict == usingExtDict) || (match >= lowPrefix)) { >>>>>> + if (offset >= 8) { >>>>>> + memcpy(op, match, 8); >>>>>> + memcpy(op + 8, match + 8, 8); >>>>>> + memcpy(op + 16, match + 16, 2); >>>>>> + op += length; >>>>>> + continue; >>>>>> + } >>>>>> + } >>>>>> + } >>>>>> + >>>>>> + /* match starting within external dictionary */ >>>>>> + if ((dict == usingExtDict) && (match < lowPrefix)) { >>>>>> + if (unlikely(op + length > oend - LASTLITERALS)) { >>>>>> + if (partialDecoding) { >>>>>> + /* reach end of buffer */ >>>>>> + length = >>>>>> + min(length, (size_t) (oend - op)); >>>>>> + } else { >>>>>> + /* end-of-block condition violated */ >>>>>> + goto _output_error; >>>>>> + } >>>>>> + } >>>>>> + >>>>>> + if (length <= (size_t) (lowPrefix - match)) { >>>>>> + /* match fits entirely within external dictionary : just copy */ >>>>>> + memmove(op, dictEnd - (lowPrefix - match), length); >>>>>> + op += length; >>>>>> + } else { >>>>>> + /* match stretches into both external dict and current block */ >>>>>> + size_t const copySize = >>>>>> + (size_t) (lowPrefix - match); >>>>>> + size_t const restSize = length - copySize; >>>>>> + memcpy(op, dictEnd - copySize, copySize); >>>>>> + op += copySize; >>>>>> + if (restSize > (size_t) (op - lowPrefix)) { /* overlap copy */ >>>>>> + BYTE *const endOfMatch = op + restSize; >>>>>> + const BYTE *copyFrom = lowPrefix; >>>>>> + while (op < endOfMatch) { >>>>>> + *op++ = *copyFrom++; >>>>>> + } >>>>>> + } else { >>>>>> + memcpy(op, lowPrefix, restSize); >>>>>> + op += restSize; >>>>>> + } >>>>>> + } >>>>>> + continue; >>>>>> + } >>>>>> + >>>>>> + /* copy match within block */ >>>>>> + cpy = op + length; >>>>>> + >>>>>> + assert((op <= oend) && (oend - op >= 32)); >>>>>> + if (unlikely(offset < 16)) { >>>>>> + LZ4_memcpy_using_offset(op, match, cpy, offset); >>>>>> + } else { >>>>>> + LZ4_wildCopy32(op, match, cpy); >>>>>> + } >>>>>> + >>>>>> + op = cpy; /* wildcopy correction */ >>>>>> + } >>>>>> + safe_decode: >>>>>> +#endif >>>>>> + /* Main Loop : decode sequences */ >>>>>> + while (1) { >>>>>> + length = token >> ML_BITS; >>>>>> >>>>>> /* ip < iend before the increment */ >>>>>> assert(!endOnInput || ip <= iend); >>>>>> @@ -143,26 +450,27 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> * combined check for both stages). >>>>>> */ >>>>>> if ((endOnInput ? length != RUN_MASK : length <= 8) >>>>>> - /* >>>>>> - * strictly "less than" on input, to re-enter >>>>>> - * the loop with at least one byte >>>>>> - */ >>>>>> - && likely((endOnInput ? ip < shortiend : 1) & >>>>>> - (op <= shortoend))) { >>>>>> + /* >>>>>> + * strictly "less than" on input, to re-enter >>>>>> + * the loop with at least one byte >>>>>> + */ >>>>>> + && likely((endOnInput ? ip < shortiend : 1) & >>>>>> + (op <= shortoend))) { >>>>>> /* Copy the literals */ >>>>>> memcpy(op, ip, endOnInput ? 16 : 8); >>>>>> - op += length; ip += length; >>>>>> + op += length; >>>>>> + ip += length; >>>>>> >>>>>> /* >>>>>> * The second stage: >>>>>> * prepare for match copying, decode full info. >>>>>> * If it doesn't work out, the info won't be wasted. >>>>>> */ >>>>>> - length = token & ML_MASK; /* match length */ >>>>>> + length = token & ML_MASK; /* match length */ >>>>>> offset = LZ4_readLE16(ip); >>>>>> ip += 2; >>>>>> match = op - offset; >>>>>> - assert(match <= op); /* check overflow */ >>>>>> + assert(match <= op); /* check overflow */ >>>>>> >>>>>> /* Do not deal with overlapping matches. */ >>>>>> if ((length != ML_MASK) && >>>>>> @@ -187,28 +495,24 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> >>>>>> /* decode literal length */ >>>>>> if (length == RUN_MASK) { >>>>>> - unsigned int s; >>>>>> >>>>>> - if (unlikely(endOnInput ? ip >= iend - RUN_MASK : 0)) { >>>>>> - /* overflow detection */ >>>>>> + variable_length_error error = ok; >>>>>> + length += >>>>>> + read_variable_length(&ip, iend - RUN_MASK, >>>>>> + endOnInput, endOnInput, >>>>>> + &error); >>>>>> + if (error == initial_error) >>>>>> goto _output_error; >>>>>> - } >>>>>> - do { >>>>>> - s = *ip++; >>>>>> - length += s; >>>>>> - } while (likely(endOnInput >>>>>> - ? ip < iend - RUN_MASK >>>>>> - : 1) & (s == 255)); >>>>>> >>>>>> if ((safeDecode) >>>>>> - && unlikely((uptrval)(op) + >>>>>> - length < (uptrval)(op))) { >>>>>> + && unlikely((uptrval) (op) + >>>>>> + length < (uptrval) (op))) { >>>>>> /* overflow detection */ >>>>>> goto _output_error; >>>>>> } >>>>>> if ((safeDecode) >>>>>> - && unlikely((uptrval)(ip) + >>>>>> - length < (uptrval)(ip))) { >>>>>> + && unlikely((uptrval) (ip) + >>>>>> + length < (uptrval) (ip))) { >>>>>> /* overflow detection */ >>>>>> goto _output_error; >>>>>> } >>>>>> @@ -216,11 +520,15 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> >>>>>> /* copy literals */ >>>>>> cpy = op + length; >>>>>> +#if LZ4_FAST_DEC_LOOP >>>>>> + safe_literal_copy: >>>>>> +#endif >>>>>> LZ4_STATIC_ASSERT(MFLIMIT >= WILDCOPYLENGTH); >>>>>> >>>>>> if (((endOnInput) && ((cpy > oend - MFLIMIT) >>>>>> - || (ip + length > iend - (2 + 1 + LASTLITERALS)))) >>>>>> - || ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) { >>>>>> + || (ip + length > >>>>>> + iend - (2 + 1 + LASTLITERALS)))) >>>>>> + || ((!endOnInput) && (cpy > oend - WILDCOPYLENGTH))) { >>>>>> if (partialDecoding) { >>>>>> if (cpy > oend) { >>>>>> /* >>>>>> @@ -231,7 +539,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> length = oend - op; >>>>>> } >>>>>> if ((endOnInput) >>>>>> - && (ip + length > iend)) { >>>>>> + && (ip + length > iend)) { >>>>>> /* >>>>>> * Error : >>>>>> * read attempt beyond >>>>>> @@ -241,7 +549,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> } >>>>>> } else { >>>>>> if ((!endOnInput) >>>>>> - && (cpy != oend)) { >>>>>> + && (cpy != oend)) { >>>>>> /* >>>>>> * Error : >>>>>> * block decoding must >>>>>> @@ -250,7 +558,7 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> goto _output_error; >>>>>> } >>>>>> if ((endOnInput) >>>>>> - && ((ip + length != iend) >>>>>> + && ((ip + length != iend) >>>>>> || (cpy > oend))) { >>>>>> /* >>>>>> * Error : >>>>>> @@ -288,29 +596,14 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> goto _output_error; >>>>>> } >>>>>> >>>>>> - /* costs ~1%; silence an msan warning when offset == 0 */ >>>>>> - /* >>>>>> - * note : when partialDecoding, there is no guarantee that >>>>>> - * at least 4 bytes remain available in output buffer >>>>>> - */ >>>>>> - if (!partialDecoding) { >>>>>> - assert(oend > op); >>>>>> - assert(oend - op >= 4); >>>>>> - >>>>>> - LZ4_write32(op, (U32)offset); >>>>>> - } >>>>>> - >>>>>> if (length == ML_MASK) { >>>>>> - unsigned int s; >>>>>> - >>>>>> - do { >>>>>> - s = *ip++; >>>>>> - >>>>>> - if ((endOnInput) && (ip > iend - LASTLITERALS)) >>>>>> - goto _output_error; >>>>>> >>>>>> - length += s; >>>>>> - } while (s == 255); >>>>>> + variable_length_error error = ok; >>>>>> + length += >>>>>> + read_variable_length(&ip, iend - LASTLITERALS + 1, >>>>>> + endOnInput, 0, &error); >>>>>> + if (error != ok) >>>>>> + goto _output_error; >>>>>> >>>>>> if ((safeDecode) >>>>>> && unlikely( >>>>>> @@ -322,6 +615,10 @@ static FORCE_INLINE int LZ4_decompress_generic( >>>>>> >>>>>> length += MINMATCH; >>>>>> >>>>>> +#if LZ4_FAST_DEC_LOOP >>>>>> +safe_match_copy: >>>>>> +#endif >>>>>> + >>>>>> /* match starting within external dictionary */ >>>>>> if ((dict == usingExtDict) && (match < lowPrefix)) { >>>>>> if (unlikely(op + length > oend - LASTLITERALS)) { >>>>>>