I am working on a feature branch.

1. Made several commits. Squashed commits.
2. Pushed changes to remote branch. Got conflicts.
3. Merged changes from master, resolved conflicts on feature branch.
   • git fetch origin master
   • git merge FETCH_HEAD
   • Resolved conflicts manually.
   • git commit
   • git push
4. I made one more commit.

So, current commit history looks like this.
From current to old:

1. commit 3
2. commit M yyy (Merged)
3. commit 2

How do I squash above 3 commits into 1 before I merge my feature branch to master?

You can rebase -i starting with commit 2‘s parent (that is, the commit on master that you branched from. You’ll likely have to re-resolve conflicts when you get to the merge commit.

So if your history looks like

Start with git rebase -i A. You’ll see a list of commits including both master and your_branch, but not the merge commit. pick the first one (B or C, depending on timing) and squash the rest.