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agda-spa/lean/Spa/Language.lean
Danila Fedorin b6b30958aa Add proof of reaching definition analysis
This requires a few pieces:

* Make node tags use `Fin n` intead of natural numbers. This makes
  it possible to build a finite lattice over AST nodes, and also
  ensure automatic, total indexing from CFG nodes into the AST that
  created them. For this, use the elaborator to derive the ordering
  statements etc. where possible.
* Adjust the forward framework to enable proofs that don't just state
  correctness on the environment, but also on an arbitrary additional
  state accumulated from traversing the trace.
* State the reaching definition analysis's correctness in terms
  of this new framework.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-27 18:56:59 -05:00

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import Spa.Language.Base
import Spa.Language.Semantics
import Spa.Language.Graphs
import Spa.Language.Traces
import Spa.Language.Properties
import Mathlib.Data.Finset.Sort
import Mathlib.Data.String.Basic
namespace Spa
structure Program where
rootStmt : Stmt
namespace Program
variable (p : Program)
def cfg : Graph := Graph.wrap p.rootStmt.cfg
abbrev State : Type := p.cfg.Index
def initialState : p.State := p.rootStmt.cfg.wrapInput
def finalState : p.State := p.rootStmt.cfg.wrapOutput
noncomputable def trace {ρ : Env} (h : EvalStmt [] p.rootStmt ρ) :
Trace p.cfg p.initialState p.finalState [] ρ := by
obtain i₁, h₁, i₂, h₂, tr := EndToEndTrace.wrap (Stmt.cfg_sufficient h)
rw [Graph.wrap_inputs, List.mem_singleton] at h₁
rw [Graph.wrap_outputs, List.mem_singleton] at h₂
subst h₁; subst h₂
exact tr
def vars : List String := p.rootStmt.vars.sort (· ·)
lemma vars_nodup : p.vars.Nodup := Finset.sort_nodup _ _
def states : List p.State := p.cfg.indices
lemma states_complete (s : p.State) : s p.states := p.cfg.mem_indices s
lemma states_nodup : p.states.Nodup := p.cfg.nodup_indices
def code (st : p.State) : Option BasicStmt := p.cfg.nodes st
def incoming (s : p.State) : List p.State := p.cfg.predecessors s
lemma incoming_initialState_eq_nil : p.incoming p.initialState = [] :=
Graph.wrap_predecessors_eq_nil p.rootStmt.cfg p.initialState
(by rw [Graph.wrap_inputs]; exact List.mem_singleton_self _)
lemma mem_incoming_of_edge {s₁ s₂ : p.State}
(h : (s₁, s₂) p.cfg.edges) : s₁ p.incoming s₂ :=
p.cfg.mem_predecessors_of_edge h
end Program
end Spa