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• Split

Vl-assign-split

Split up assignments with complex right-hand sides.

Signature

(vl-assign-split x delta) → (mv new-x delta)

Arguments

x — Guard (vl-assign-p x).

delta — Guard (vl-delta-p delta).

Returns

new-x — Type (vl-assign-p new-x), given the guard.

delta — Type (vl-delta-p delta), given the guard.

This is a little more interesting than usual. We want to split up the right-hand side of an assignment only if it is a compound expression that involves unsliceable arguments. That is, we don't want to split up assignments like:

• foo = bar -- no operations
• foo = bar[3] -- no "non-wiring" operations
• foo = bar + 1 -- just one operation
• foo = bar[3] & foo[4] -- just one "non-wiring" operation

But we do want to split up anything more complicated, for instance, if we have:

foo = bar + (baz + 1)

Then we want to split, because we have a top-level operator who has an argument, (baz + 1), that isn't sliceable.

Definitions and Theorems

Function: vl-assign-split

(defun vl-assign-split (x delta)
  (declare (xargs :guard (and (vl-assign-p x)
                              (vl-delta-p delta))))
  (let ((__function__ 'vl-assign-split))
    (declare (ignorable __function__))
    (b* (((vl-assign x) x)
         ((when (vl-nosplit-p x.expr))
          (mv x delta))
         (args (vl-nonatom->args x.expr))
         ((when (vl-nosplitlist-p args))
          (mv x delta))
         ((mv new-args delta)
          (vl-exprlist-split args x delta))
         (new-expr (change-vl-nonatom x.expr
                                      :args new-args))
         (x-prime (change-vl-assign x :expr new-expr)))
      (mv x-prime delta))))

Theorem: vl-assign-p-of-vl-assign-split.new-x

(defthm vl-assign-p-of-vl-assign-split.new-x
  (implies (and (force (vl-assign-p x))
                (force (vl-delta-p delta)))
           (b* (((mv ?new-x ?delta)
                 (vl-assign-split x delta)))
             (vl-assign-p new-x)))
  :rule-classes :rewrite)

Theorem: vl-delta-p-of-vl-assign-split.delta

(defthm vl-delta-p-of-vl-assign-split.delta
  (implies (and (force (vl-assign-p x))
                (force (vl-delta-p delta)))
           (b* (((mv ?new-x ?delta)
                 (vl-assign-split x delta)))
             (vl-delta-p delta)))
  :rule-classes :rewrite)