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
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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