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agda-spa/lean/Spa/Analysis/Forward.lean
2026-06-23 11:44:50 -05:00

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import Spa.Analysis.Forward.Lattices
import Spa.Analysis.Forward.Evaluation
import Spa.Analysis.Forward.Adapters
import Spa.Fixedpoint
namespace Spa
variable {L : Type} [Lattice L] {prog : Program} [E : StmtEvaluator L prog]
def updateVariablesForState (s : prog.State) (sv : StateVariables L prog) :
VariableValues L prog :=
(prog.code s).foldl (fun vs bs => E.eval s bs vs) (variablesAt s sv)
theorem updateVariablesForState_mono (s : prog.State) :
Monotone (updateVariablesForState (L := L) s) := fun _ _ hle =>
foldl_mono' (prog.code s) _ (E.eval_mono s ·) (variablesAt_le hle s)
def updateAll (sv : StateVariables L prog) : StateVariables L prog :=
FiniteMap.generalizedUpdate id updateVariablesForState
prog.states sv
theorem updateAll_mono : Monotone (updateAll (L := L) (prog := prog)) :=
FiniteMap.generalizedUpdate_monotone monotone_id updateVariablesForState_mono
theorem updateAll_mem_eq {s : prog.State} {vs : VariableValues L prog}
{sv : StateVariables L prog} (hmem : (s, vs) updateAll sv) :
vs = updateVariablesForState s sv :=
FiniteMap.generalizedUpdate_mem_eq (prog.states_complete s) hmem
theorem variablesAt_updateAll (s : prog.State) (sv : StateVariables L prog) :
variablesAt s (updateAll sv) = updateVariablesForState s sv :=
updateAll_mem_eq (variablesAt_mem s (updateAll sv))
variable [FiniteHeightLattice L]
def analyze (sv : StateVariables L prog) : StateVariables L prog :=
updateAll (joinAll sv)
theorem analyze_mono : Monotone (analyze (L := L) (prog := prog)) := fun _ _ hle =>
updateAll_mono (joinAll_mono hle)
variable [DecidableEq L]
variable (L prog) in
def result : StateVariables L prog :=
Fixedpoint.aFix analyze analyze_mono
variable (L prog) in
theorem result_eq : result L prog = analyze (result L prog) :=
Fixedpoint.aFix_eq analyze analyze_mono
theorem joinForKey_initialState :
joinForKey prog.initialState (result L prog) = botV L prog := by
rw [joinForKey, prog.incoming_initialState_eq_nil]
rfl
variable [I : LatticeInterpretation L] [V : ValidStmtEvaluator L prog]
omit [FiniteHeightLattice L] [DecidableEq L] in
theorem eval_fold_valid {s : prog.State} {bss : List BasicStmt}
{vs : VariableValues L prog} {ρ₁ ρ₂ : Env}
(hbss : EvalBasicStmts ρ₁ bss ρ₂) (hvs : interpV vs ρ₁) :
interpV (bss.foldl (fun vs bs => E.eval s bs vs) vs) ρ₂ := by
induction hbss generalizing vs with
| nil => exact hvs
| cons hbs _ ih => exact ih (ValidStmtEvaluator.valid hbs hvs)
omit [FiniteHeightLattice L] [DecidableEq L] in
theorem updateVariablesForState_matches {s : prog.State}
{sv : StateVariables L prog} {ρ₁ ρ₂ : Env}
(hbss : EvalBasicStmts ρ₁ (prog.code s) ρ₂)
(hvs : interpV (variablesAt s sv) ρ₁) :
interpV (updateVariablesForState s sv) ρ₂ :=
eval_fold_valid hbss hvs
omit [FiniteHeightLattice L] [DecidableEq L] in
theorem updateAll_matches {s : prog.State} {sv : StateVariables L prog}
{ρ₁ ρ₂ : Env} (hbss : EvalBasicStmts ρ₁ (prog.code s) ρ₂)
(hvs : interpV (variablesAt s sv) ρ₁) :
interpV (variablesAt s (updateAll sv)) ρ₂ := by
rw [variablesAt_updateAll]
exact updateVariablesForState_matches hbss hvs
theorem stepTrace {s₁ : prog.State} {ρ₁ ρ₂ : Env}
(hjoin : interpV (joinForKey s₁ (result L prog)) ρ₁)
(hbss : EvalBasicStmts ρ₁ (prog.code s₁) ρ₂) :
interpV (variablesAt s₁ (result L prog)) ρ₂ := by
rw [result_eq L prog]
refine updateAll_matches hbss ?_
rw [variablesAt_joinAll]
exact hjoin
theorem walkTrace {s₁ s₂ : prog.State} {ρ₁ ρ₂ : Env}
(hjoin : interpV (joinForKey s₁ (result L prog)) ρ₁)
(tr : Trace prog.graph s₁ s₂ ρ₁ ρ₂) :
interpV (variablesAt s₂ (result L prog)) ρ₂ := by
induction tr with
| single hbss => exact stepTrace hjoin hbss
| @edge _ ρ' _ i₁ i₂ _ hbss hedge _ ih =>
have hstep : interpV (variablesAt i₁ (result L prog)) ρ' :=
stepTrace hjoin hbss
have hmem : variablesAt i₁ (result L prog)
(result L prog).valuesAt (prog.incoming i₂) :=
FiniteMap.mem_valuesAt prog.states_nodup
(prog.mem_incoming_of_edge hedge) (variablesAt_mem i₁ (result L prog))
exact ih (interpV_foldr hstep hmem)
omit V in
theorem interpV_joinForKey_initialState :
interpV (joinForKey prog.initialState (result L prog)) [] := by
rw [joinForKey_initialState]
exact interpV_botV_nil
variable (L prog) in
theorem analyze_correct {ρ : Env} (hrun : EvalStmt [] prog.rootStmt ρ) :
interpV (variablesAt prog.finalState (result L prog)) ρ :=
walkTrace interpV_joinForKey_initialState (prog.trace hrun)
end Spa