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• Vl-casestmt-compare-expr

Vl-casestmt-compare-expr1

Creates, e.g., the expression foo === 3'b110, for handling case(foo) ... 3'b110: ... endcase.

Signature

(vl-casestmt-compare-expr1 test expr) → compare-expr

Arguments

test — The test expression, e.g., foo.
    Guard (vl-expr-p test).

expr — One match expression, e.g., 3'b110.
    Guard (vl-expr-p expr).

Returns

compare-expr — Type (vl-expr-p compare-expr).

This is mostly dealing with sizing. Recall from 5.5.1 that comparisons always produce unsigned results. Our guard is strong enough to ensure that we'll always have equal-width expressions and that we know their types. We haven't assumed anything about their types agreeing. To make sure that we produce well-typed expressions, we'll coerce anything signed into an unsigned equivalent, by just wrapping it in a one-bit concatenation.

Definitions and Theorems

Function: vl-casestmt-compare-expr1

(defun vl-casestmt-compare-expr1 (test expr)
 (declare (xargs :guard (and (vl-expr-p test)
                             (vl-expr-p expr))))
 (declare (xargs :guard (and (vl-expr->finaltype test)
                             (vl-expr->finaltype expr)
                             (posp (vl-expr->finalwidth test))
                             (equal (vl-expr->finalwidth test)
                                    (vl-expr->finalwidth expr)))))
 (let ((__function__ 'vl-casestmt-compare-expr1))
  (declare (ignorable __function__))
  (b*
   ((width (vl-expr->finalwidth test))
    (test-fix
        (case (vl-expr->finaltype test)
              (:vl-unsigned test)
              (:vl-signed (make-vl-nonatom :op :vl-concat
                                           :args (list test)
                                           :finalwidth width
                                           :finaltype :vl-unsigned))
              (otherwise (progn$ (impossible) test))))
    (expr-fix
        (case (vl-expr->finaltype expr)
              (:vl-unsigned expr)
              (:vl-signed (make-vl-nonatom :op :vl-concat
                                           :args (list expr)
                                           :finalwidth width
                                           :finaltype :vl-unsigned))
              (otherwise (progn$ (impossible) expr)))))
   (make-vl-nonatom :op :vl-binary-ceq
                    :args (list test-fix expr-fix)
                    :finaltype :vl-unsigned
                    :finalwidth 1))))

Theorem: vl-expr-p-of-vl-casestmt-compare-expr1

(defthm vl-expr-p-of-vl-casestmt-compare-expr1
  (b* ((compare-expr (vl-casestmt-compare-expr1 test expr)))
    (vl-expr-p compare-expr))
  :rule-classes :rewrite)

Theorem: vl-expr->finalwidth-of-vl-casestmt-compare-expr1

(defthm vl-expr->finalwidth-of-vl-casestmt-compare-expr1
  (b* ((compare-expr (vl-casestmt-compare-expr1 test expr)))
    (equal (vl-expr->finalwidth compare-expr)
           1))
  :rule-classes :rewrite)

Theorem: vl-expr->finaltype-of-vl-casestmt-compare-expr1

(defthm vl-expr->finaltype-of-vl-casestmt-compare-expr1
  (b* ((compare-expr (vl-casestmt-compare-expr1 test expr)))
    (equal (vl-expr->finaltype compare-expr)
           :vl-unsigned))
  :rule-classes :rewrite)

Theorem: vl-expr-welltyped-p-of-vl-casestmt-compare-expr1

(defthm vl-expr-welltyped-p-of-vl-casestmt-compare-expr1
  (implies
       (and (force (posp (vl-expr->finalwidth test)))
            (force (vl-expr->finaltype test))
            (force (vl-expr->finaltype expr))
            (force (equal (vl-expr->finalwidth test)
                          (vl-expr->finalwidth expr)))
            (force (vl-expr-welltyped-p test))
            (force (vl-expr-welltyped-p expr)))
       (vl-expr-welltyped-p (vl-casestmt-compare-expr1 test expr))))

Theorem: vl-casestmt-compare-expr1-of-vl-expr-fix-test

(defthm vl-casestmt-compare-expr1-of-vl-expr-fix-test
  (equal (vl-casestmt-compare-expr1 (vl-expr-fix test)
                                    expr)
         (vl-casestmt-compare-expr1 test expr)))

Theorem: vl-casestmt-compare-expr1-vl-expr-equiv-congruence-on-test

(defthm vl-casestmt-compare-expr1-vl-expr-equiv-congruence-on-test
  (implies (vl-expr-equiv test test-equiv)
           (equal (vl-casestmt-compare-expr1 test expr)
                  (vl-casestmt-compare-expr1 test-equiv expr)))
  :rule-classes :congruence)

Theorem: vl-casestmt-compare-expr1-of-vl-expr-fix-expr

(defthm vl-casestmt-compare-expr1-of-vl-expr-fix-expr
  (equal (vl-casestmt-compare-expr1 test (vl-expr-fix expr))
         (vl-casestmt-compare-expr1 test expr)))

Theorem: vl-casestmt-compare-expr1-vl-expr-equiv-congruence-on-expr

(defthm vl-casestmt-compare-expr1-vl-expr-equiv-congruence-on-expr
  (implies (vl-expr-equiv expr expr-equiv)
           (equal (vl-casestmt-compare-expr1 test expr)
                  (vl-casestmt-compare-expr1 test expr-equiv)))
  :rule-classes :congruence)