What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind bug
/kind task
/kind feature

/kind feature

What does this PR do / why do we need it:
Resolve nodes swell issue with control flow after grad operation.

  • Replace primal graph with fprop of k graph after grad operation.

Which issue(s) this PR fixes:

Fixes #I1UFVW:【STABLE】【控制流】控制流场景下cse图优化问题

Special notes for your reviewers: