Improve stability of accuracy in `DE_BFD`

[kimikage]

This makes it less likely that muladd will make the difference between being fused or not.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.90%. Comparing base (f0a508b) to head (17aaf86). Report is 5 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #545 +/- ## ========================================== + Coverage 98.82% 98.90% +0.07% ========================================== Files 10 10 Lines 1281 1281 ========================================== + Hits 1266 1267 +1 + Misses 15 14 -1 ```

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