Meghana Gupta 581f611195 ARCSequenceOpts: Add LoopSummary verifier (#33810) ...

ARCSequenceOpts with loop support works on regions inside out.
While processing an outer region, it uses summary from
the inner loop region to compute RefCountState transitions used for
CodeMotionSafe optimization.

We do not compute the loop summary by iterating over it twice or
iterating until a fixed point is reached.
Instead loop summary is just a list of refcount effecting instructions.
And BottomUpRefCountState::updateForDifferentLoopInst and
TopDownRefCountState::updateForDifferentLoopInst are used to compute the
RefCountState transition when processing the inner loop region. These
functions are very conservative and the flow sensitive nature of the
summarized instructions do no matter.
This PR adds a verifying assert to confirm this.

2020-09-15 09:27:37 -07:00

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