[drlvm] [ipf] new gira HARMONY-2207 for ipf suggested

[Igor Chebykin]

Hi all,

I suggest new patch
  https://issues.apache.org/jira/browse/HARMONY-2207
for ipf codegenerator.

It is mostly for "auto" constant propagation/folding.
Also, minor fix in encoder and minor code optimizations included.

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Best regards,
Igor.