fix[venom]: fix incorrect write reordering in DFTPass

[charles-cooper]

What I did

How I did it

How to verify it

Commit message

fix incorrect write-after-write and write-after-read reordering in
DFT pass.

- writes should be fenced by writes
- writes should be fenced by *all* prior reads, not just the most
  recent read

Description for the changelog

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.96%. Comparing base (67ea4ee) to head (2fc9b24).
⚠️ Report is 29 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4695      +/-   ##
==========================================
+ Coverage   92.93%   92.96%   +0.02%     
==========================================
  Files         131      131              
  Lines       19062    19067       +5     
  Branches     3316     3319       +3     
==========================================
+ Hits        17716    17725       +9     
+ Misses        904      902       -2     
+ Partials      442      440       -2     

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