[polly] r271128 - Determination of statements that contain matrix multiplication

[Michael Kruse via llvm-commits]

2016-05-31 23:40 GMT+02:00 Mehdi Amini via llvm-commits
<llvm-commits at lists.llvm.org>:

>> +/// @brief Circular shift of output dimensions of the integer map.
>> +///
>> +/// @param IslMap The isl map to be modified.
>> +static __isl_give isl_map *circularShiftOutputDims(__isl_take isl_map *IslMap) {
>> +  auto InputDimsId = isl_map_get_tuple_id(IslMap, isl_dim_in);
>> +  auto DimNum = isl_map_dim(IslMap, isl_dim_out);
>> +  IslMap = isl_map_move_dims(IslMap, isl_dim_in, 0, isl_dim_out, DimNum - 1, 1);
>> +  IslMap = isl_map_move_dims(IslMap, isl_dim_out, 0, isl_dim_in, 0, 1);
>> +  return isl_map_set_tuple_id(IslMap, isl_dim_in, InputDimsId);
>> +}
>
> Coverity is reporting a potential issue here:
>
> *** CID 1356130:  Insecure data handling  (INTEGER_OVERFLOW)
> /tools/polly/lib/Transform/ScheduleOptimizer.cpp: 469 in circularShiftOutputDims(isl_map *)()
> 463     /// @param IslMap The isl map to be modified.
> 464     static __isl_give isl_map *circularShiftOutputDims(__isl_take isl_map *IslMap) {
> 465       auto InputDimsId = isl_map_get_tuple_id(IslMap, isl_dim_in);
> 466       auto DimNum = isl_map_dim(IslMap, isl_dim_out);
> 467       IslMap = isl_map_move_dims(IslMap, isl_dim_in, 0, isl_dim_out, DimNum - 1, 1);
> 468       IslMap = isl_map_move_dims(IslMap, isl_dim_out, 0, isl_dim_in, 0, 1);
>>>>     CID 1356130:  Insecure data handling  (INTEGER_OVERFLOW)
>>>>     Overflowed or truncated value (or a value computed from an overflowed or truncated value) "isl_map_set_tuple_id(IslMap, isl_dim_in, InputDimsId)" used as return value.
> 469       return isl_map_set_tuple_id(IslMap, isl_dim_in, InputDimsId);
> 470     }
>
>

Can you explain the message? The only integer used in that line is
isl_dim_in, and its a constant as used elsewhere as well.

I find a different possible underflow with the expression "DimNum -
1", as DimNum is unsigned. Might happen if the map has 0 range
dimensions which probably never happens.

Michael