Lean migration: Phase 6 (forward analysis framework)

- Spa.Analysis.Forward.Lattices: VariableValues/StateVariables (FiniteMap
  instantiations), fixed heights, variablesAt, joinForKey/joinAll, interpV
  and its sup/foldr lemmas
- Spa.Analysis.Forward.Evaluation: StmtEvaluator/ExprEvaluator + validity
  (the Agda Valid* instance records become plain Props)
- Spa.Analysis.Forward.Adapters: expr-to-stmt evaluator adapter + validity
- Spa.Analysis.Forward: updateAll, analyze, result (least fixpoint via the
  gas-based Fixedpoint), walkTrace, analyze_correct — the framework's main
  soundness theorem

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
2026-06-09 20:14:53 -07:00
parent 2cfd0a2fb7
commit 739fbb503c
6 changed files with 443 additions and 1 deletions

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/-
Port of `Analysis/Forward/Adapters.agda` (`ExprToStmtAdapter`).
Correspondence:
updateVariablesFromExpression ↦ updateVariablesFromExpression
updateVariablesFromExpression-Mono ↦ updateVariablesFromExpression_mono
(the -k∈ks-/ -k∉ks-backward renames ↦ used directly from FiniteMap)
evalᵇ, evalᵇ-Monoʳ ↦ evalB, evalB_mono
stmtEvaluator (instance) ↦ ExprEvaluator.toStmtEvaluator
evalᵇ-valid, validStmtEvaluator ↦ ExprEvaluator.toStmtEvaluator_valid
(the Agda `k ≟ˢ k'` case split is
subsumed by `cases` on `Env.Mem`,
whose `here` case forces `k' = k`)
-/
import Spa.Analysis.Forward.Evaluation
namespace Spa
variable {L : Type} [Lattice L] {prog : Program}
/-- Agda: `updateVariablesFromExpression` — set the single key `k` to the
value of `e` (the `GeneralizedUpdate` with `ks = [k]`). -/
def updateVariablesFromExpression (E : ExprEvaluator L prog) (k : String)
(e : Expr) (vs : VariableValues L prog) : VariableValues L prog :=
FiniteMap.generalizedUpdate id (fun _ vs => E.eval e vs) [k] vs
/-- Agda: `updateVariablesFromExpression-Mono`. -/
theorem updateVariablesFromExpression_mono (E : ExprEvaluator L prog)
(k : String) (e : Expr) :
Monotone (updateVariablesFromExpression E k e) :=
FiniteMap.generalizedUpdate_monotone monotone_id (fun _ => E.eval_mono e)
/-- Agda: `evalᵇ`. -/
def evalB (E : ExprEvaluator L prog) (_ : prog.State) (bs : BasicStmt)
(vs : VariableValues L prog) : VariableValues L prog :=
match bs with
| .assign k e => updateVariablesFromExpression E k e vs
| .noop => vs
/-- Agda: `evalᵇ-Monoʳ`. -/
theorem evalB_mono (E : ExprEvaluator L prog) (s : prog.State) (bs : BasicStmt) :
Monotone (evalB E s bs) := by
cases bs with
| assign k e => exact updateVariablesFromExpression_mono E k e
| noop => exact monotone_id
/-- Agda: the `stmtEvaluator` instance of `ExprToStmtAdapter`. -/
def ExprEvaluator.toStmtEvaluator (E : ExprEvaluator L prog) :
StmtEvaluator L prog :=
evalB E, evalB_mono E
/-- Agda: `evalᵇ-valid` / the `validStmtEvaluator` instance. -/
theorem ExprEvaluator.toStmtEvaluator_valid (E : ExprEvaluator L prog)
{I : LatticeInterpretation L} (hE : IsValidExprEvaluator E I) :
IsValidStmtEvaluator E.toStmtEvaluator I := by
intro s vs ρ₁ ρ₂ bs hbs hvs
cases hbs with
| noop => exact hvs
| assign k e v hev =>
intro k' l hk'l v' hv'
cases hv' with
| here =>
have hk'l₀ : (k, l) FiniteMap.generalizedUpdate (ks := prog.vars) id
(fun _ vs => E.eval e vs) [k] vs := hk'l
have hl := FiniteMap.generalizedUpdate_mem_eq (f := id)
(g := fun _ vs => E.eval e vs) (List.mem_singleton_self k) hk'l₀
rw [hl]
exact hE hev hvs
| there _ _ _ _ _ hne hmem' =>
have hk'l₀ : (k', l) FiniteMap.generalizedUpdate (ks := prog.vars) id
(fun _ vs => E.eval e vs) [k] vs := hk'l
have hk'l' : (k', l) (id vs : VariableValues L prog) :=
FiniteMap.generalizedUpdate_not_mem_backward
(fun hmem => hne (List.mem_singleton.mp hmem)) hk'l₀
exact hvs _ _ hk'l' _ hmem'
end Spa

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/-
Port of `Analysis/Forward/Evaluation.agda`.
Correspondence:
StmtEvaluator (eval, eval-Monoʳ) ↦ StmtEvaluator (eval, eval_mono)
ExprEvaluator (eval, eval-Monoʳ) ↦ ExprEvaluator (eval, eval_mono)
IsValidExprEvaluator ↦ IsValidExprEvaluator
IsValidStmtEvaluator ↦ IsValidStmtEvaluator
ValidExprEvaluator,
ValidStmtEvaluator (records) ↦ (the `IsValid…` Props are passed
directly; the wrapper records existed
for Agda instance resolution)
-/
import Spa.Analysis.Forward.Lattices
namespace Spa
variable (L : Type) [Lattice L] (prog : Program)
/-- Agda: `StmtEvaluator`. -/
structure StmtEvaluator where
eval : prog.State BasicStmt VariableValues L prog VariableValues L prog
eval_mono : s bs, Monotone (eval s bs)
/-- Agda: `ExprEvaluator`. -/
structure ExprEvaluator where
eval : Expr VariableValues L prog L
eval_mono : e, Monotone (eval e)
variable {L prog}
/-- Agda: `IsValidExprEvaluator`. -/
def IsValidExprEvaluator (E : ExprEvaluator L prog)
(I : LatticeInterpretation L) : Prop :=
{vs : VariableValues L prog} {ρ : Env} {e : Expr} {v : Value},
EvalExpr ρ e v interpV I vs ρ I.interp (E.eval e vs) v
/-- Agda: `IsValidStmtEvaluator`. -/
def IsValidStmtEvaluator (E : StmtEvaluator L prog)
(I : LatticeInterpretation L) : Prop :=
{s : prog.State} {vs : VariableValues L prog} {ρ₁ ρ₂ : Env} {bs : BasicStmt},
EvalBasicStmt ρ₁ bs ρ₂ interpV I vs ρ₁ interpV I (E.eval s bs vs) ρ₂
end Spa

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/-
Port of `Analysis/Forward/Lattices.agda`.
The Agda module instantiates `Lattice.FiniteMap` twice (variables ↦ abstract
values, states ↦ variable maps) and re-exports everything with ᵛ/ᵐ suffixes.
In Lean the two instantiations are `abbrev`s and the FiniteMap API is used
directly; the module parameters (the finite-height lattice `L`, the program)
become section variables.
Correspondence:
VariableValues, StateVariables ↦ VariableValues, StateVariables
isLatticeᵛ/isLatticeᵐ, ⊔ᵛ, ≼ᵛ … ↦ (the FiniteMap Lattice instances)
fixedHeightᵛ ↦ varsFixedHeight
⊥ᵛ, ⊥ᵛ-contains-bottoms ↦ botV, FiniteMap.bot_contains_bots
states-in-Map ↦ states_memKey
variablesAt ↦ variablesAt
variablesAt-∈ ↦ variablesAt_mem
variablesAt-≈ ↦ (congruence, trivial with `=`)
joinForKey, joinForKey-Mono ↦ joinForKey, joinForKey_mono
joinAll, joinAll-Mono,
joinAll-k∈ks-≡ ↦ joinAll, joinAll_mono, joinAll_mem_eq
variablesAt-joinAll ↦ variablesAt_joinAll
⟦_⟧ᵛ ↦ interpV
⟦⊥ᵛ⟧ᵛ∅ ↦ interpV_botV_nil
⟦⟧ᵛ-respects-≈ᵛ ↦ (trivial with `=`)
⟦⟧ᵛ-⊔ᵛ- ↦ interpV_sup
⟦⟧ᵛ-foldr ↦ interpV_foldr
-/
import Spa.Language
import Spa.Lattice.FiniteMap
namespace Spa
variable (L : Type) [Lattice L] (prog : Program)
/-- Agda: `VariableValues`. -/
abbrev VariableValues : Type := FiniteMap String L prog.vars
/-- Agda: `StateVariables`. -/
abbrev StateVariables : Type := FiniteMap prog.State (VariableValues L prog) prog.states
variable {h : }
/-- Agda: `fixedHeightᵛ`. -/
def varsFixedHeight (fhL : FixedHeight L h) :
FixedHeight (VariableValues L prog) (prog.vars.length * h) :=
FiniteMap.fixedHeight fhL prog.vars
/-- Agda: `⊥ᵛ`. -/
def botV (fhL : FixedHeight L h) : VariableValues L prog :=
(varsFixedHeight L prog fhL).bot
/-- Agda: `fixedHeight` on `StateVariables` (assembled in `Forward.agda`'s
fixpoint call; named here for reuse). -/
def statesFixedHeight (fhL : FixedHeight L h) :
FixedHeight (StateVariables L prog) (prog.states.length * (prog.vars.length * h)) :=
FiniteMap.fixedHeight (varsFixedHeight L prog fhL) prog.states
variable {L prog}
omit [Lattice L] in
/-- Agda: `states-in-Map`. -/
theorem states_memKey (s : prog.State) (sv : StateVariables L prog) :
FiniteMap.MemKey s sv :=
FiniteMap.memKey_iff.mpr (prog.states_complete s)
/-- Agda: `variablesAt`. -/
def variablesAt (s : prog.State) (sv : StateVariables L prog) :
VariableValues L prog :=
(FiniteMap.locate (states_memKey s sv)).1
omit [Lattice L] in
/-- Agda: `variablesAt-∈`. -/
theorem variablesAt_mem (s : prog.State) (sv : StateVariables L prog) :
(s, variablesAt s sv) sv :=
(FiniteMap.locate (states_memKey s sv)).2
/-- Agda: `m₁≼m₂⇒m₁[k]ᵐ≼m₂[k]ᵐ`, specialized the way `Forward.agda` uses it. -/
theorem variablesAt_le {sv₁ sv₂ : StateVariables L prog} (hle : sv₁ sv₂)
(s : prog.State) : variablesAt s sv₁ variablesAt s sv₂ :=
FiniteMap.le_of_mem_mem prog.states_nodup hle
(variablesAt_mem s sv₁) (variablesAt_mem s sv₂)
variable (fhL : FixedHeight L h)
/-- Agda: `joinForKey`. -/
def joinForKey (k : prog.State) (sv : StateVariables L prog) :
VariableValues L prog :=
(sv.valuesAt (prog.incoming k)).foldr (· ·) (botV L prog fhL)
/-- Agda: `joinForKey-Mono`. -/
theorem joinForKey_mono (k : prog.State) :
Monotone (joinForKey fhL k) := by
intro sv₁ sv₂ hle
exact foldr_mono _ (FiniteMap.valuesAt_le hle (prog.incoming k)) (le_refl _)
(fun b _ _ hab => sup_le_sup_right hab b)
(fun a _ _ hab => sup_le_sup_left hab a)
/-- Agda: `joinAll` (the "Exercise 4.26" generalized update with `f = id`). -/
def joinAll (sv : StateVariables L prog) : StateVariables L prog :=
FiniteMap.generalizedUpdate id (joinForKey fhL) prog.states sv
/-- Agda: `joinAll-Mono`. -/
theorem joinAll_mono : Monotone (joinAll (prog := prog) fhL) :=
FiniteMap.generalizedUpdate_monotone monotone_id (joinForKey_mono fhL)
/-- Agda: `joinAll-k∈ks-≡`. -/
theorem joinAll_mem_eq {s : prog.State} {vs : VariableValues L prog}
{sv : StateVariables L prog} (h : (s, vs) joinAll fhL sv) :
vs = joinForKey fhL s sv :=
FiniteMap.generalizedUpdate_mem_eq (prog.states_complete s) h
/-- Agda: `variablesAt-joinAll`. -/
theorem variablesAt_joinAll (s : prog.State) (sv : StateVariables L prog) :
variablesAt s (joinAll fhL sv) = joinForKey fhL s sv :=
joinAll_mem_eq fhL (variablesAt_mem s (joinAll fhL sv))
/-! ### Lifting an interpretation to variable maps -/
variable (I : LatticeInterpretation L)
/-- Agda: `⟦_⟧ᵛ`. -/
def interpV (vs : VariableValues L prog) (ρ : Env) : Prop :=
(k : String) (l : L), (k, l) vs
(v : Value), Env.Mem (k, v) ρ I.interp l v
/-- Agda: `⟦⊥ᵛ⟧ᵛ∅`. -/
theorem interpV_botV_nil : interpV I (botV L prog fhL) [] := by
intro k l _ v hmem
cases hmem
/-- Agda: `⟦⟧ᵛ-⊔ᵛ-`. -/
theorem interpV_sup {vs₁ vs₂ : VariableValues L prog} {ρ : Env}
(h : interpV I vs₁ ρ interpV I vs₂ ρ) : interpV I (vs₁ vs₂) ρ := by
intro k l hmem v hv
obtain l₁, l₂, rfl, h₁, h₂ := FiniteMap.mem_sup hmem
rcases h with h | h
· exact I.interp_sup v (Or.inl (h _ _ h₁ _ hv))
· exact I.interp_sup v (Or.inr (h _ _ h₂ _ hv))
/-- Agda: `⟦⟧ᵛ-foldr`. -/
theorem interpV_foldr {vs : VariableValues L prog}
{vss : List (VariableValues L prog)} {ρ : Env}
(hvs : interpV I vs ρ) (hmem : vs vss) :
interpV I (vss.foldr (· ·) (botV L prog fhL)) ρ := by
induction vss with
| nil => cases hmem
| cons vs' vss' ih =>
rcases List.mem_cons.mp hmem with rfl | hmem'
· exact interpV_sup I (Or.inl hvs)
· exact interpV_sup I (Or.inr (ih hmem'))
end Spa