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 DAB32C04E53 for ; Thu, 16 May 2019 01:49:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F36220843 for ; Thu, 16 May 2019 01:49:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726581AbfEPBqX convert rfc822-to-8bit (ORCPT ); Wed, 15 May 2019 21:46:23 -0400 Received: from cnbjsegrel01.sonyericsson.com ([219.141.167.163]:5319 "EHLO CNBJSEGREL01.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726542AbfEOXsx (ORCPT ); Wed, 15 May 2019 19:48:53 -0400 Subject: Re: [PATCH 1/1] LZ4: Port LZ4 1.9.x FAST_DEC_LOOP and enable it on x86 and ARM64 To: Gao Xiang , Cyan 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 , Greg Kroah-Hartman References: <20190515004336.66555-1-chenxi.mao@sony.com> <649ba9ed-223e-1e82-1513-f3c16e4c8f9a@huawei.com> <0c1d0d7d24ae48f68ae6acc95c0c4869@CNBJMBX12.corpusers.net> From: "Mao, Chenxi" Message-ID: <5c735ce9-04fc-a2a4-4f0c-ba5718fe7933@sony.com> Date: Thu, 16 May 2019 07:48:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. @Xiang: Do you prefer to upgrade kernel lz4 to 1.9.1 directly or only pick some optimization patches? 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)) { >>>>>