Possible shift by negative amount in modules arm_lms_norm_q31 and am_lms_norm_q15

[localuser2]

Compiling current CMSIS for Host platfom (AMD64) while gcc's static code analysis feature is active results in serious looking errors.

GCC version:

$ gcc --version
gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

GCC arguments:

/usr/bin/x86_64-linux-gnu-gcc -DARM_MATH_LOOPUNROLL -D__GNUC_PYTHON__ -I/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/PrivateInclude -I/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include -g -Og -Wall -Wextra -Werror -I /home/klose/projects/MARS2/mars/dev_policies/cxx/cmake/../include/ -fanalyzer -MD -MT mars-processing-bin/src/cmsis_dsp_bin/FilteringFunctions/CMakeFiles/CMSISDSPFiltering.dir/arm_lms_norm_q15.c.obj -MF CMakeFiles/CMSISDSPFiltering.dir/arm_lms_norm_q15.c.obj.d -o CMakeFiles/CMSISDSPFiltering.dir/arm_lms_norm_q15.c.obj -c /home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Source/FilteringFunctions/arm_lms_norm_q15.c

GCC code analyzer warnings (with the configuration shown above this are errors due to -Werror):

/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Source/FilteringFunctions/arm_lms_norm_q31.c:189:9: error: shift by negative count (‘-1’) [-Werror=analyzer-shift-count-negative]
  189 |     w = clip_q63_to_q31(((q63_t) errorXmu * oneByEnergy) >> (31 - postShift));
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ‘arm_lms_norm_q31’: events 1-2
    |
    |  102 |   while (blkCnt > 0U)
    |      |          ~~~~~~~^~~~
    |      |                 |
    |      |                 (1) following ‘true’ branch (when ‘blkCnt != 0’)...
    |......
    |  105 |     *pStateCurnt++ = *pSrc;
    |      |     ~            
    |      |     |
    |      |     (2) ...to here
    |
  ‘arm_lms_norm_q31’: event 3
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include/dsp/none.h:65:10:
    |   65 |       if (data == 0U) { return 32U; }
    |      |          ^
    |      |          |
    |      |          (3) following ‘true’ branch...
    |
  ‘arm_lms_norm_q31’: events 4-6
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include/dsp/utils.h:63:31:
    |   63 |       signBits = ((uint32_t) (__CLZ( in) - 1));
    |      |                               ^~~~~~~~~~
    |      |                               |
    |      |                               (4) ...to here
    |......
    |   82 |     for (i = 0U; i < 2U; i++)
    |      |                  ~~~~~~        
    |      |                    |
    |      |                    (5) following ‘true’ branch (when ‘i <= 1’)...
    |   83 |     {
    |   84 |       tempVal = (uint32_t) (((q63_t) in * out) >> 31);
    |      |       ~~~~~~~                  
    |      |       |
    |      |       (6) ...to here
    |
  ‘arm_lms_norm_q31’: event 7
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Source/FilteringFunctions/arm_lms_norm_q31.c:189:9:
    |  189 |     w = clip_q63_to_q31(((q63_t) errorXmu * oneByEnergy) >> (31 - postShift));
    |      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    |      |         |
    |      |         (7) shift by negative amount here (‘-1’)
    |
cc1: all warnings being treated as errors
make[2]: *** [mars-processing-bin/src/cmsis_dsp_bin/FilteringFunctions/CMakeFiles/CMSISDSPFiltering.dir/build.make:1420: mars-processing-bin/src/cmsis_dsp_bin/FilteringFunctions/CMakeFiles/CMSISDSPFiltering.dir/arm_lms_norm_q31.c.obj] Fehler 1
make[2]: *** Auf noch nicht beendete Prozesse wird gewartet …
/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include/dsp/utils.h: In function ‘arm_lms_norm_q15’:
/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Source/FilteringFunctions/arm_lms_norm_q15.c:185:45: error: shift by negative count (‘-1’) [-Werror=analyzer-shift-count-negative]
  185 |     acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
  ‘arm_lms_norm_q15’: events 1-2
    |
    |  102 |   while (blkCnt > 0U)
    |      |          ~~~~~~~^~~~
    |      |                 |
    |      |                 (1) following ‘true’ branch (when ‘blkCnt != 0’)...
    |......
    |  105 |     *pStateCurnt++ = *pSrc;
    |      |     ~            
    |      |     |
    |      |     (2) ...to here
    |
  ‘arm_lms_norm_q15’: event 3
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include/dsp/none.h:65:10:
    |   65 |       if (data == 0U) { return 32U; }
    |      |          ^
    |      |          |
    |      |          (3) following ‘true’ branch...
    |
  ‘arm_lms_norm_q15’: events 4-6
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Include/dsp/utils.h:114:30:
    |  114 |       signBits = ((uint32_t)(__CLZ( in) - 17));
    |      |                              ^~~~~~~~~~
    |      |                              |
    |      |                              (4) ...to here
    |......
    |  133 |     for (i = 0U; i < 2U; i++)
    |      |                  ~~~~~~       
    |      |                    |
    |      |                    (5) following ‘true’ branch (when ‘i <= 1’)...
    |  134 |     {
    |  135 |       tempVal = (uint32_t) (((q31_t) in * out) >> 15);
    |      |       ~~~~~~~                 
    |      |       |
    |      |       (6) ...to here
    |
  ‘arm_lms_norm_q15’: event 7
    |
    |/home/klose/projects/MARS2/mars/cxx/libraries/mars-processing/src/CMSIS/CMSIS/DSP/Source/FilteringFunctions/arm_lms_norm_q15.c:185:45:
    |  185 |     acc = (((q31_t) errorXmu * oneByEnergy) >> (15 - postShift));
    |      |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
    |      |                                             |
    |      |                                             (7) shift by negative amount here (‘-1’)
    |

[JonatanAntoni]

Hi @localuser2,

Please take note that CMSIS-DSP has moved into its own repository at https://github.com/ARM-software/CMSIS-DSP. Please consider raising your issue over there.

Thanks,
Jonatan