Generalize pooling accumulator inference

[jmduarte]

Currently, pooling uses a wider data type for accumulation inferred based on the input type and the number of elements. However, we only implemented this for ap_fixed<W,I> and ap_int<W> and the template matching fails for ap_uint<W> and ap_ufixed<W,I,Q,O> and ap_fixed<W,I,Q,O> (if Q and O are not the default values). This PR (hopefully) makes it so it matches all those additional types.

Type of change

• [x] Bug fix (non-breaking change that fixes an issue)
• [x] New feature (non-breaking change which adds functionality)

Tests

Example before this fix:

Example after this fix:

Checklist

• [x] I have read the guidelines for contributing.
• [ ] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have made corresponding changes to the documentation.
• [ ] My changes generate no new warnings.
• [ ] I have installed and run pre-commit on the files I edited or added.
• [ ] I have added tests that prove my fix is effective or that my feature works.

@Brainz22 @ddiaz006 @AnthonyAportela @danprim

[jmduarte]

Do we need a corresponding fix for Quartus?

https://github.com/fastmachinelearning/hls4ml/blob/f41951c57883022362dd4ffbe6ce3ed4efe36811/hls4ml/templates/quartus/firmware/nnet_utils/nnet_pooling.h#L38-L74

[jmduarte]

pre-commit.ci autofix

[calad0i]

Currently, there is an accum_t set for pooling layers which is only effective for io_stream implementation: vivado_backend.py#L376-L380, nnet_pooling_stream.h#L386. (Which could also be problematic at the moment, see #917.)

Maybe we should converge on whether to set pooling accumulator size with accum_t or cpp template matching? @vloncar

[jmitrevs]

Do we need a corresponding fix for Quartus?

https://github.com/fastmachinelearning/hls4ml/blob/f41951c57883022362dd4ffbe6ce3ed4efe36811/hls4ml/templates/quartus/firmware/nnet_utils/nnet_pooling.h#L38-L74

Actually I think it also needs to be done for vitis (which has its own implementation) in addition to quartus.

[jmitrevs]

What did we decide to do about accum_t vs template matching?

[jmitrevs]

My general feeling is to prefer the #973 style solution, though implementation details may still need to be addressed.

[jmitrevs]

We decided to go with #973 so I will close this PR.