A tone equalizer in darktable ?

Nope.
Here is the compilator output

[ 56%] Building C object src/iop/CMakeFiles/toneequal.dir/introspection_toneequal.c.obj
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:83,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:413:20: error: the call requires 'ifunc', which is not supported by this target
  413 | static inline void fast_guided_filter(float *const restrict image,
      |                    ^~~~~~~~~~~~~~~~~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:613:9: error: the call requires 'ifunc', which is not supported by this target
  613 | #pragma omp parallel for simd schedule(static) default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:725:9: error: the call requires 'ifunc', which is not supported by this target
  725 | #pragma omp parallel for simd default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:698:9: error: the call requires 'ifunc', which is not supported by this target
  698 | #pragma omp parallel for default(none) schedule(simd:static) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:1252:9: error: the call requires 'ifunc', which is not supported by this target
 1252 | #pragma omp parallel sections
      |         ^~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:27,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:83,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/sse.h:30:9: error: the call requires 'ifunc', which is not supported by this target
   30 | #pragma omp parallel for simd default(none) \
      |         ^~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:99,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:401:11: error: the call requires 'ifunc', which is not supported by this target
  401 |   #pragma omp parallel sections
      |           ^~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:880:9: error: the call requires 'ifunc', which is not supported by this target
  880 | #pragma omp parallel for simd default(none) schedule(static) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:559:9: error: the call requires 'ifunc', which is not supported by this target
  559 | #pragma omp parallel for default(none) schedule(static) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:852:9: error: the call requires 'ifunc', which is not supported by this target
  852 | #pragma omp parallel for simd default(none) \
      |         ^~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:85,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:308:1: error: the call requires 'ifunc', which is not supported by this target
  308 |       LOOP(pixel_rgb_geomean);
      | ^
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:305:1: error: the call requires 'ifunc', which is not supported by this target
  305 |       LOOP(pixel_rgb_norm_power);
      | ^
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:302:1: error: the call requires 'ifunc', which is not supported by this target
  302 |       LOOP(pixel_rgb_norm_2);
      | ^
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:299:1: error: the call requires 'ifunc', which is not supported by this target
  299 |       LOOP(pixel_rgb_norm_1);
      | ^
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:296:1: error: the call requires 'ifunc', which is not supported by this target
  296 |       LOOP(pixel_rgb_value);
      | ^
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:293:1: error: the call requires 'ifunc', which is not supported by this target
  293 |       LOOP(pixel_rgb_lightness);
      | ^
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:85,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:290:1: error: the call requires 'ifunc', which is not supported by this target
  290 |       LOOP(pixel_rgb_mean);
      | ^
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:83,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:355:9: error: the call requires 'ifunc', which is not supported by this target
  355 | #pragma omp parallel for simd default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:336:9: error: the call requires 'ifunc', which is not supported by this target
  336 | #pragma omp parallel for simd default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:98:9: error: the call requires 'ifunc', which is not supported by this target
   98 | #pragma omp parallel for simd collapse(2) default(none) schedule(static) aligned(in, out:64) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:298:9: error: the call requires 'ifunc', which is not supported by this target
  298 | #pragma omp parallel for default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:269:9: error: the call requires 'ifunc', which is not supported by this target
  269 | #pragma omp parallel for default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:207:9: error: the call requires 'ifunc', which is not supported by this target
  207 | #pragma omp parallel for default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:169:9: error: the call requires 'ifunc', which is not supported by this target
  169 | #pragma omp parallel for default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:402:9: error: the call requires 'ifunc', which is not supported by this target
  402 | #pragma omp parallel for simd default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:390:9: error: the call requires 'ifunc', which is not supported by this target
  390 | #pragma omp parallel for simd default(none) \
      |         ^~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:379:9: error: the call requires 'ifunc', which is not supported by this target
  379 | #pragma omp parallel for simd default(none) \
      |         ^~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:1236:19: error: the call requires 'ifunc', which is not supported by this target
 1236 | static inline int radial_approximation(float A[(CHANNELS + 1) * PIXEL_CHAN],
      |                   ^~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:918:6: error: the call requires 'ifunc', which is not supported by this target
  918 | void process(struct dt_iop_module_t *self, dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
      |      ^~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:893:20: error: the call requires 'ifunc', which is not supported by this target
  893 | static inline void apply_toneequalizer(const float *const restrict in,
      |                    ^~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:864:20: error: the call requires 'ifunc', which is not supported by this target
  864 | static inline void apply_exposure(const float *const restrict in, float *const restrict out,
      |                    ^~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:836:20: error: the call requires 'ifunc', which is not supported by this target
  836 | static inline void display_luminance_mask(const float *const restrict luminance,
      |                    ^~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:716:21: error: the call requires 'ifunc', which is not supported by this target
  716 | static inline float flat_pseudo_norm(const float *const restrict image, const size_t num_elem)
      |                     ^~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:681:20: error: the call requires 'ifunc', which is not supported by this target
  681 | static inline void compute_log_histogram(const float *const restrict luminance,
      |                    ^~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:628:20: error: the call requires 'ifunc', which is not supported by this target
  628 | static inline void compute_luminance_mask(const float *const restrict in, float *const restrict luminance,
      |                    ^~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:601:13: error: the call requires 'ifunc', which is not supported by this target
  601 | static void compute_lut_correction(struct dt_iop_toneequalizer_gui_data_t *g,
      |             ^~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:581:14: error: the call requires 'ifunc', which is not supported by this target
  581 | static float pixel_correction(const float exposure,
      |              ^~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:550:20: error: the call requires 'ifunc', which is not supported by this target
  550 | static inline void compute_correction(const float *const restrict luminance,
      |                    ^~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:540:14: error: the call requires 'ifunc', which is not supported by this target
  540 | static float gaussian_func(const float radius, const float denominator)
      |              ^~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:527:14: error: the call requires 'ifunc', which is not supported by this target
  527 | static float gaussian_denom(const float sigma)
      |              ^~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:481:14: error: the call requires 'ifunc', which is not supported by this target
  481 | static float get_luminance_from_buffer(const float *const buffer,
      |              ^~~~~~~~~~~~~~~~~~~~~~~~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:99,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:374:19: error: the call requires 'ifunc', which is not supported by this target
  374 | static inline int pseudo_solve(float *const restrict A,
      |                   ^~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:355:19: error: the call requires 'ifunc', which is not supported by this target
  355 | static inline int transpose_dot_vector(float *const restrict A, // input
      |                   ^~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:335:19: error: the call requires 'ifunc', which is not supported by this target
  335 | static inline int transpose_dot_matrix(float *const restrict A, // input
      |                   ^~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:268:19: error: the call requires 'ifunc', which is not supported by this target
  268 | static inline int solve_hermitian(const float *const restrict A,
      |                   ^~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:239:19: error: the call requires 'ifunc', which is not supported by this target
  239 | static inline int triangular_ascent_safe(const float *const restrict L,
      |                   ^~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:220:19: error: the call requires 'ifunc', which is not supported by this target
  220 | static inline int triangular_ascent_fast(const float *const restrict L,
      |                   ^~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:191:19: error: the call requires 'ifunc', which is not supported by this target
  191 | static inline int triangular_descent_safe(const float *const restrict L,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:172:19: error: the call requires 'ifunc', which is not supported by this target
  172 | static inline int triangular_descent_fast(const float *const restrict L,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:124:19: error: the call requires 'ifunc', which is not supported by this target
  124 | static inline int choleski_decompose_safe(const float *const restrict A,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/choleski.h:99:19: error: the call requires 'ifunc', which is not supported by this target
   99 | static inline int choleski_decompose_fast(const float *const restrict A,
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:85,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:280:20: error: the call requires 'ifunc', which is not supported by this target
  280 | static inline void luminance_mask(const float *const restrict in, float *const restrict out,
      |                    ^~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:230:13: error: the call requires 'ifunc', which is not supported by this target
  230 | static void pixel_rgb_geomean(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:200:13: error: the call requires 'ifunc', which is not supported by this target
  200 | static void pixel_rgb_norm_power(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:177:13: error: the call requires 'ifunc', which is not supported by this target
  177 | static void pixel_rgb_norm_2(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:153:13: error: the call requires 'ifunc', which is not supported by this target
  153 | static void pixel_rgb_norm_1(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:136:13: error: the call requires 'ifunc', which is not supported by this target
  136 | static void pixel_rgb_lightness(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:119:13: error: the call requires 'ifunc', which is not supported by this target
  119 | static void pixel_rgb_value(const float *const restrict image,
      |             ^~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:95:13: error: the call requires 'ifunc', which is not supported by this target
   95 | static void pixel_rgb_mean(const float *const restrict image,
      |             ^~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/luminance_mask.h:84:14: error: the call requires 'ifunc', which is not supported by this target
   84 | static float linear_contrast(const float pixel, const float fulcrum, const float contrast)
      |              ^~~~~~~~~~~~~~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:83,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:368:20: error: the call requires 'ifunc', which is not supported by this target
  368 | static inline void quantize(const float *const restrict image,
      |                    ^~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:349:20: error: the call requires 'ifunc', which is not supported by this target
  349 | static inline void apply_linear_blending_w_geomean(float *const restrict image,
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:330:20: error: the call requires 'ifunc', which is not supported by this target
  330 | static inline void apply_linear_blending(float *const restrict image,
      |                    ^~~~~~~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:257:20: error: the call requires 'ifunc', which is not supported by this target
  257 | static inline void box_average(float *const restrict in,
      |                    ^~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:151:20: error: the call requires 'ifunc', which is not supported by this target
  151 | static inline void variance_analyse(const float *const restrict guide, // I
      |                    ^~~~~~~~~~~~~~~~
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:92:20: error: the call requires 'ifunc', which is not supported by this target
   92 | static inline void interpolate_bilinear(const float *const restrict in, const size_t width_in, const size_t height_in,
      |                    ^~~~~~~~~~~~~~~~~~~~
In file included from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/fast_guided_filter.h:27,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/iop/toneequal.c:83,
                 from C:/msys64/home/marco/darktable-2.7-equalizer/darktable/build/src/iop/introspection_toneequal.c:77:
C:/msys64/home/marco/darktable-2.7-equalizer/darktable/src/common/sse.h:22:20: error: the call requires 'ifunc', which is not supported by this target
   22 | static inline void dt_simd_memcpy(const float *const restrict in,
      |                    ^~~~~~~~~~~~~~
make[2]: *** [src/iop/CMakeFiles/toneequal.dir/build.make:68: src/iop/CMakeFiles/toneequal.dir/introspection_toneequal.c.obj] Error 1
make[1]: *** [CMakeFiles/Makefile2:3455: src/iop/CMakeFiles/toneequal.dir/all] Error 2
make: *** [Makefile:152: all] Error 2