Hi Nick,

[auto build test WARNING on linus/master]
[also build test WARNING on v4.13-rc2 next-20170724]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improve the system]

url:    
https://github.com/0day-ci/linux/commits/Nick-Terrell/Add-xxhash-and-zstd-modules/20170723-092845
config: x86_64-randconfig-a0-07242221 (attached as .config)
compiler: gcc-4.4 (Debian 4.4.7-8) 4.4.7
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   lib/zstd/decompress.c: In function 'ZSTD_decodeSequence':
>> lib/zstd/decompress.c:1001: warning: 'seq.match' is used uninitialized in 
>> this function

vim +1001 lib/zstd/decompress.c

dc22844b Nick Terrell 2017-07-20   930  
dc22844b Nick Terrell 2017-07-20   931  static seq_t 
ZSTD_decodeSequence(seqState_t *seqState)
dc22844b Nick Terrell 2017-07-20   932  {
dc22844b Nick Terrell 2017-07-20   933          seq_t seq;
dc22844b Nick Terrell 2017-07-20   934  
dc22844b Nick Terrell 2017-07-20   935          U32 const llCode = 
FSE_peekSymbol(&seqState->stateLL);
dc22844b Nick Terrell 2017-07-20   936          U32 const mlCode = 
FSE_peekSymbol(&seqState->stateML);
dc22844b Nick Terrell 2017-07-20   937          U32 const ofCode = 
FSE_peekSymbol(&seqState->stateOffb); /* <= maxOff, by table construction */
dc22844b Nick Terrell 2017-07-20   938  
dc22844b Nick Terrell 2017-07-20   939          U32 const llBits = 
LL_bits[llCode];
dc22844b Nick Terrell 2017-07-20   940          U32 const mlBits = 
ML_bits[mlCode];
dc22844b Nick Terrell 2017-07-20   941          U32 const ofBits = ofCode;
dc22844b Nick Terrell 2017-07-20   942          U32 const totalBits = llBits + 
mlBits + ofBits;
dc22844b Nick Terrell 2017-07-20   943  
dc22844b Nick Terrell 2017-07-20   944          static const U32 LL_base[MaxLL 
+ 1] = {0,  1,  2,  3,  4,  5,  6,  7,  8,    9,     10,    11,    12,    13,   
  14,     15,     16,     18,
dc22844b Nick Terrell 2017-07-20   945                                          
       20, 22, 24, 28, 32, 40, 48, 64, 0x80, 0x100, 0x200, 0x400, 0x800, 
0x1000, 0x2000, 0x4000, 0x8000, 0x10000};
dc22844b Nick Terrell 2017-07-20   946  
dc22844b Nick Terrell 2017-07-20   947          static const U32 ML_base[MaxML 
+ 1] = {3,  4,  5,  6,  7,  8,  9,  10,   11,    12,    13,    14,    15,     
16,     17,     18,     19,     20,
dc22844b Nick Terrell 2017-07-20   948                                          
       21, 22, 23, 24, 25, 26, 27, 28,   29,    30,    31,    32,    33,     
34,     35,     37,     39,     41,
dc22844b Nick Terrell 2017-07-20   949                                          
       43, 47, 51, 59, 67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803, 0x1003, 
0x2003, 0x4003, 0x8003, 0x10003};
dc22844b Nick Terrell 2017-07-20   950  
dc22844b Nick Terrell 2017-07-20   951          static const U32 OF_base[MaxOff 
+ 1] = {0,       1,     1,      5,      0xD,      0x1D,      0x3D,      0x7D,   
   0xFD,     0x1FD,
dc22844b Nick Terrell 2017-07-20   952                                          
        0x3FD,   0x7FD,    0xFFD,    0x1FFD,   0x3FFD,   0x7FFD,    0xFFFD,    
0x1FFFD,   0x3FFFD,  0x7FFFD,
dc22844b Nick Terrell 2017-07-20   953                                          
        0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD, 0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, 
0x7FFFFFD, 0xFFFFFFD};
dc22844b Nick Terrell 2017-07-20   954  
dc22844b Nick Terrell 2017-07-20   955          /* sequence */
dc22844b Nick Terrell 2017-07-20   956          {
dc22844b Nick Terrell 2017-07-20   957                  size_t offset;
dc22844b Nick Terrell 2017-07-20   958                  if (!ofCode)
dc22844b Nick Terrell 2017-07-20   959                          offset = 0;
dc22844b Nick Terrell 2017-07-20   960                  else {
dc22844b Nick Terrell 2017-07-20   961                          offset = 
OF_base[ofCode] + BIT_readBitsFast(&seqState->DStream, ofBits); /* <=  
(ZSTD_WINDOWLOG_MAX-1) bits */
dc22844b Nick Terrell 2017-07-20   962                          if 
(ZSTD_32bits())
dc22844b Nick Terrell 2017-07-20   963                                  
BIT_reloadDStream(&seqState->DStream);
dc22844b Nick Terrell 2017-07-20   964                  }
dc22844b Nick Terrell 2017-07-20   965  
dc22844b Nick Terrell 2017-07-20   966                  if (ofCode <= 1) {
dc22844b Nick Terrell 2017-07-20   967                          offset += 
(llCode == 0);
dc22844b Nick Terrell 2017-07-20   968                          if (offset) {
dc22844b Nick Terrell 2017-07-20   969                                  size_t 
temp = (offset == 3) ? seqState->prevOffset[0] - 1 : 
seqState->prevOffset[offset];
dc22844b Nick Terrell 2017-07-20   970                                  temp += 
!temp; /* 0 is not valid; input is corrupted; force offset to 1 */
dc22844b Nick Terrell 2017-07-20   971                                  if 
(offset != 1)
dc22844b Nick Terrell 2017-07-20   972                                          
seqState->prevOffset[2] = seqState->prevOffset[1];
dc22844b Nick Terrell 2017-07-20   973                                  
seqState->prevOffset[1] = seqState->prevOffset[0];
dc22844b Nick Terrell 2017-07-20   974                                  
seqState->prevOffset[0] = offset = temp;
dc22844b Nick Terrell 2017-07-20   975                          } else {
dc22844b Nick Terrell 2017-07-20   976                                  offset 
= seqState->prevOffset[0];
dc22844b Nick Terrell 2017-07-20   977                          }
dc22844b Nick Terrell 2017-07-20   978                  } else {
dc22844b Nick Terrell 2017-07-20   979                          
seqState->prevOffset[2] = seqState->prevOffset[1];
dc22844b Nick Terrell 2017-07-20   980                          
seqState->prevOffset[1] = seqState->prevOffset[0];
dc22844b Nick Terrell 2017-07-20   981                          
seqState->prevOffset[0] = offset;
dc22844b Nick Terrell 2017-07-20   982                  }
dc22844b Nick Terrell 2017-07-20   983                  seq.offset = offset;
dc22844b Nick Terrell 2017-07-20   984          }
dc22844b Nick Terrell 2017-07-20   985  
dc22844b Nick Terrell 2017-07-20   986          seq.matchLength = 
ML_base[mlCode] + ((mlCode > 31) ? BIT_readBitsFast(&seqState->DStream, mlBits) 
: 0); /* <=  16 bits */
dc22844b Nick Terrell 2017-07-20   987          if (ZSTD_32bits() && (mlBits + 
llBits > 24))
dc22844b Nick Terrell 2017-07-20   988                  
BIT_reloadDStream(&seqState->DStream);
dc22844b Nick Terrell 2017-07-20   989  
dc22844b Nick Terrell 2017-07-20   990          seq.litLength = LL_base[llCode] 
+ ((llCode > 15) ? BIT_readBitsFast(&seqState->DStream, llBits) : 0); /* <=  16 
bits */
dc22844b Nick Terrell 2017-07-20   991          if (ZSTD_32bits() || (totalBits 
> 64 - 7 - (LLFSELog + MLFSELog + OffFSELog)))
dc22844b Nick Terrell 2017-07-20   992                  
BIT_reloadDStream(&seqState->DStream);
dc22844b Nick Terrell 2017-07-20   993  
dc22844b Nick Terrell 2017-07-20   994          /* ANS state update */
dc22844b Nick Terrell 2017-07-20   995          
FSE_updateState(&seqState->stateLL, &seqState->DStream); /* <=  9 bits */
dc22844b Nick Terrell 2017-07-20   996          
FSE_updateState(&seqState->stateML, &seqState->DStream); /* <=  9 bits */
dc22844b Nick Terrell 2017-07-20   997          if (ZSTD_32bits())
dc22844b Nick Terrell 2017-07-20   998                  
BIT_reloadDStream(&seqState->DStream);             /* <= 18 bits */
dc22844b Nick Terrell 2017-07-20   999          
FSE_updateState(&seqState->stateOffb, &seqState->DStream); /* <=  8 bits */
dc22844b Nick Terrell 2017-07-20  1000  
dc22844b Nick Terrell 2017-07-20 @1001          return seq;
dc22844b Nick Terrell 2017-07-20  1002  }
dc22844b Nick Terrell 2017-07-20  1003  

:::::: The code at line 1001 was first introduced by commit
:::::: dc22844bd66de07e2ff858aaebfe678b94df529c lib: Add zstd modules

:::::: TO: Nick Terrell <terre...@fb.com>
:::::: CC: 0day robot <fengguang...@intel.com>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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