-- Mathlib/.lake/packages/lean4/src/lean/Std/Tactic/BVDecide/Bitblast/BVExpr/Circuit/Lemmas/Expr.lean
theorem go_denote_eq (aig : AIG BVBit) (expr : BVExpr w) (assign : Assignment) :
    ∀ (idx : Nat) (hidx : idx < w),
        ⟦(go aig expr).val.aig, (go aig expr).val.vec.get idx hidx, assign.toAIGAssignment⟧
          =
        (expr.eval assign).getLsbD idx

Proof state:
case arithShiftRight.hleft
w : Nat
assign : Assignment
m✝ n✝ : Nat
lhs : BVExpr m✝
rhs : BVExpr n✝
lih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < m✝),
    ⟦assign.toAIGAssignment, { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx hidx }⟧ =
      (eval assign lhs).getLsbD idx
rih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < n✝),
    ⟦assign.toAIGAssignment, { aig := (go aig rhs).val.aig, ref := (go aig rhs).val.vec.get idx hidx }⟧ =
      (eval assign rhs).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < m✝
idx✝ : Nat
hidx✝ : idx✝ < m✝
⊢ ⟦assign.toAIGAssignment,
      { aig := (go aig lhs).1.aig,
        ref :=
          { gate := (((go aig lhs).1.vec.cast ⋯).get idx✝ hidx✝).gate, hgate := ?arithShiftRight.hleft.hstart } }⟧ =
    (eval assign lhs).getLsbD idx✝

case arithShiftRight.hleft.hstart
w : Nat
assign : Assignment
m✝ n✝ : Nat
lhs : BVExpr m✝
rhs : BVExpr n✝
lih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < m✝),
    ⟦assign.toAIGAssignment, { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx hidx }⟧ =
      (eval assign lhs).getLsbD idx
rih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < n✝),
    ⟦assign.toAIGAssignment, { aig := (go aig rhs).val.aig, ref := (go aig rhs).val.vec.get idx hidx }⟧ =
      (eval assign rhs).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < m✝
idx✝ : Nat
hidx✝ : idx✝ < m✝
⊢ (((go aig lhs).1.vec.cast ⋯).get idx✝ hidx✝).gate < (go aig lhs).1.aig.decls.size

Tactic:
rw [← lih (aig := aig)]

Result:
case arithShiftRight.hleft
w : Nat
assign : Assignment
m✝ n✝ : Nat
lhs : BVExpr m✝
rhs : BVExpr n✝
lih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < m✝),
    ⟦assign.toAIGAssignment, { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx hidx }⟧ =
      (eval assign lhs).getLsbD idx
rih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < n✝),
    ⟦assign.toAIGAssignment, { aig := (go aig rhs).val.aig, ref := (go aig rhs).val.vec.get idx hidx }⟧ =
      (eval assign rhs).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < m✝
idx✝ : Nat
hidx✝ : idx✝ < m✝
⊢ ⟦assign.toAIGAssignment,
      { aig := (go aig lhs).1.aig,
        ref :=
          { gate := (((go aig lhs).1.vec.cast ⋯).get idx✝ hidx✝).gate, hgate := ?arithShiftRight.hleft.hstart } }⟧ =
    ⟦assign.toAIGAssignment,
      { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx✝ ?arithShiftRight.hleft.hidx }⟧

case arithShiftRight.hleft.hidx
w : Nat
assign : Assignment
m✝ n✝ : Nat
lhs : BVExpr m✝
rhs : BVExpr n✝
lih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < m✝),
    ⟦assign.toAIGAssignment, { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx hidx }⟧ =
      (eval assign lhs).getLsbD idx
rih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < n✝),
    ⟦assign.toAIGAssignment, { aig := (go aig rhs).val.aig, ref := (go aig rhs).val.vec.get idx hidx }⟧ =
      (eval assign rhs).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < m✝
idx✝ : Nat
hidx✝ : idx✝ < m✝
⊢ idx✝ < m✝

case arithShiftRight.hleft.hstart
w : Nat
assign : Assignment
m✝ n✝ : Nat
lhs : BVExpr m✝
rhs : BVExpr n✝
lih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < m✝),
    ⟦assign.toAIGAssignment, { aig := (go aig lhs).val.aig, ref := (go aig lhs).val.vec.get idx hidx }⟧ =
      (eval assign lhs).getLsbD idx
rih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < n✝),
    ⟦assign.toAIGAssignment, { aig := (go aig rhs).val.aig, ref := (go aig rhs).val.vec.get idx hidx }⟧ =
      (eval assign rhs).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < m✝
idx✝ : Nat
hidx✝ : idx✝ < m✝
⊢ (((go aig lhs).1.vec.cast ⋯).get idx✝ hidx✝).gate < (go aig lhs).1.aig.decls.size

Proof state:
case extract
w✝ : Nat
assign : Assignment
w start len : Nat
inner : BVExpr w
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < w),
    ⟦assign.toAIGAssignment, { aig := (go aig inner).val.aig, ref := (go aig inner).val.vec.get idx hidx }⟧ =
      (eval assign inner).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < len
⊢ ⟦assign.toAIGAssignment,
      { aig := (go aig (extract start len inner)).val.aig,
        ref := (go aig (extract start len inner)).val.vec.get idx hidx }⟧ =
    (eval assign (extract start len inner)).getLsbD idx

Tactic:
simp only [go, denote_blastExtract, Bool.if_false_right, eval_extract,
  BitVec.getLsbD_extractLsb', hidx, decide_true, Bool.true_and]

Result:
case extract
w✝ : Nat
assign : Assignment
w start len : Nat
inner : BVExpr w
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < w),
    ⟦assign.toAIGAssignment, { aig := (go aig inner).val.aig, ref := (go aig inner).val.vec.get idx hidx }⟧ =
      (eval assign inner).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < len
⊢ (if h : start + idx < w then
      ⟦assign.toAIGAssignment, { aig := (go aig inner).1.aig, ref := (go aig inner).1.vec.get (start + idx) ⋯ }⟧
    else false) =
    (eval assign inner).getLsbD (start + idx)

Proof state:
case signExtend
w : Nat
assign : Assignment
originalWidth v : Nat
inner : BVExpr originalWidth
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < originalWidth),
    ⟦assign.toAIGAssignment, { aig := (go aig inner).val.aig, ref := (go aig inner).val.vec.get idx hidx }⟧ =
      (eval assign inner).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < v
res : RefVecEntry BVBit v
hgo : (go aig (signExtend v inner)).val = res
⊢ ⟦assign.toAIGAssignment, { aig := res.aig, ref := res.vec.get idx hidx }⟧ =
    (eval assign (signExtend v inner)).getLsbD idx

Tactic:
unfold go at hgo

Result:
case signExtend
w : Nat
assign : Assignment
originalWidth v : Nat
inner : BVExpr originalWidth
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < originalWidth),
    ⟦assign.toAIGAssignment, { aig := (go aig inner).val.aig, ref := (go aig inner).val.vec.get idx hidx }⟧ =
      (eval assign inner).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < v
res : RefVecEntry BVBit v
hgo :
  (match go aig inner with
      | ⟨{ aig := aig_1, vec := evec }, haig⟩ =>
        let res := blastSignExtend aig_1 { w := originalWidth, vec := evec };
        let_fun this := ⋯;
        ⟨res, this⟩).val =
    res
⊢ ⟦assign.toAIGAssignment, { aig := res.aig, ref := res.vec.get idx hidx }⟧ =
    (eval assign (signExtend v inner)).getLsbD idx

Proof state:
case un.shiftRightConst
w : Nat
assign : Assignment
w✝ : Nat
expr : BVExpr w✝
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < w✝),
    ⟦assign.toAIGAssignment, { aig := (go aig expr).val.aig, ref := (go aig expr).val.vec.get idx hidx }⟧ =
      (eval assign expr).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < w✝
n✝ : Nat
⊢ ⟦assign.toAIGAssignment,
      { aig := (go aig (un (BVUnOp.shiftRightConst n✝) expr)).val.aig,
        ref := (go aig (un (BVUnOp.shiftRightConst n✝) expr)).val.vec.get idx hidx }⟧ =
    (eval assign (un (BVUnOp.shiftRightConst n✝) expr)).getLsbD idx

Tactic:
simp only [go, denote_blastShiftRightConst, ih, dite_eq_ite, Bool.if_false_right, eval_un,
  BVUnOp.eval_shiftRightConst, BitVec.getLsbD_ushiftRight, Bool.and_iff_right_iff_imp,
  decide_eq_true_eq]

Result:
case un.shiftRightConst
w : Nat
assign : Assignment
w✝ : Nat
expr : BVExpr w✝
ih :
  ∀ (aig : AIG BVBit) (idx : Nat) (hidx : idx < w✝),
    ⟦assign.toAIGAssignment, { aig := (go aig expr).val.aig, ref := (go aig expr).val.vec.get idx hidx }⟧ =
      (eval assign expr).getLsbD idx
aig : AIG BVBit
idx : Nat
hidx : idx < w✝
n✝ : Nat
⊢ (eval assign expr).getLsbD (n✝ + idx) = true → n✝ + idx < w✝