diff options
Diffstat (limited to 'backend/CSE2.v')
-rw-r--r-- | backend/CSE2.v | 506 |
1 files changed, 506 insertions, 0 deletions
diff --git a/backend/CSE2.v b/backend/CSE2.v new file mode 100644 index 00000000..38a46c1b --- /dev/null +++ b/backend/CSE2.v @@ -0,0 +1,506 @@ +(* +Replace available expressions by the register containing their value. + +David Monniaux, CNRS, VERIMAG + *) + +Require Import Coqlib Maps Errors Integers Floats Lattice Kildall. +Require Import AST Linking. +Require Import Memory Registers Op RTL Maps. + +(* Static analysis *) + +Inductive sym_val : Type := +| SMove (src : reg) +| SOp (op : operation) (args : list reg) +| SLoad (chunk : memory_chunk) (addr : addressing) (args : list reg). + +Definition eq_args (x y : list reg) : { x = y } + { x <> y } := + list_eq_dec peq x y. + +Definition eq_sym_val : forall x y : sym_val, + {x = y} + { x <> y }. +Proof. + generalize eq_operation. + generalize eq_args. + generalize peq. + generalize eq_addressing. + generalize chunk_eq. + decide equality. +Defined. + +Module RELATION. + +Definition t := (PTree.t sym_val). +Definition eq (r1 r2 : t) := + forall x, (PTree.get x r1) = (PTree.get x r2). + +Definition top : t := PTree.empty sym_val. + +Lemma eq_refl: forall x, eq x x. +Proof. + unfold eq. + intros; reflexivity. +Qed. + +Lemma eq_sym: forall x y, eq x y -> eq y x. +Proof. + unfold eq. + intros; eauto. +Qed. + +Lemma eq_trans: forall x y z, eq x y -> eq y z -> eq x z. +Proof. + unfold eq. + intros; congruence. +Qed. + +Definition sym_val_beq (x y : sym_val) := + if eq_sym_val x y then true else false. + +Definition beq (r1 r2 : t) := PTree.beq sym_val_beq r1 r2. + +Lemma beq_correct: forall r1 r2, beq r1 r2 = true -> eq r1 r2. +Proof. + unfold beq, eq. intros r1 r2 EQ x. + pose proof (PTree.beq_correct sym_val_beq r1 r2) as CORRECT. + destruct CORRECT as [CORRECTF CORRECTB]. + pose proof (CORRECTF EQ x) as EQx. + clear CORRECTF CORRECTB EQ. + unfold sym_val_beq in *. + destruct (r1 ! x) as [R1x | ] in *; + destruct (r2 ! x) as [R2x | ] in *; + trivial; try contradiction. + destruct (eq_sym_val R1x R2x) in *; congruence. +Qed. + +Definition ge (r1 r2 : t) := + forall x, + match PTree.get x r1 with + | None => True + | Some v => (PTree.get x r2) = Some v + end. + +Lemma ge_refl: forall r1 r2, eq r1 r2 -> ge r1 r2. +Proof. + unfold eq, ge. + intros r1 r2 EQ x. + pose proof (EQ x) as EQx. + clear EQ. + destruct (r1 ! x). + - congruence. + - trivial. +Qed. + +Lemma ge_trans: forall x y z, ge x y -> ge y z -> ge x z. +Proof. + unfold ge. + intros r1 r2 r3 GE12 GE23 x. + pose proof (GE12 x) as GE12x; clear GE12. + pose proof (GE23 x) as GE23x; clear GE23. + destruct (r1 ! x); trivial. + destruct (r2 ! x); congruence. +Qed. + +Definition lub (r1 r2 : t) := + PTree.combine + (fun ov1 ov2 => + match ov1, ov2 with + | (Some v1), (Some v2) => + if eq_sym_val v1 v2 + then ov1 + else None + | None, _ + | _, None => None + end) + r1 r2. + +Lemma ge_lub_left: forall x y, ge (lub x y) x. +Proof. + unfold ge, lub. + intros r1 r2 x. + rewrite PTree.gcombine by reflexivity. + destruct (_ ! _); trivial. + destruct (_ ! _); trivial. + destruct (eq_sym_val _ _); trivial. +Qed. + +Lemma ge_lub_right: forall x y, ge (lub x y) y. +Proof. + unfold ge, lub. + intros r1 r2 x. + rewrite PTree.gcombine by reflexivity. + destruct (_ ! _); trivial. + destruct (_ ! _); trivial. + destruct (eq_sym_val _ _); trivial. + congruence. +Qed. + +End RELATION. + +Module Type SEMILATTICE_WITHOUT_BOTTOM. + + Parameter t: Type. + Parameter eq: t -> t -> Prop. + Axiom eq_refl: forall x, eq x x. + Axiom eq_sym: forall x y, eq x y -> eq y x. + Axiom eq_trans: forall x y z, eq x y -> eq y z -> eq x z. + Parameter beq: t -> t -> bool. + Axiom beq_correct: forall x y, beq x y = true -> eq x y. + Parameter ge: t -> t -> Prop. + Axiom ge_refl: forall x y, eq x y -> ge x y. + Axiom ge_trans: forall x y z, ge x y -> ge y z -> ge x z. + Parameter lub: t -> t -> t. + Axiom ge_lub_left: forall x y, ge (lub x y) x. + Axiom ge_lub_right: forall x y, ge (lub x y) y. + +End SEMILATTICE_WITHOUT_BOTTOM. + +Module ADD_BOTTOM(L : SEMILATTICE_WITHOUT_BOTTOM). + Definition t := option L.t. + Definition eq (a b : t) := + match a, b with + | None, None => True + | Some x, Some y => L.eq x y + | Some _, None | None, Some _ => False + end. + + Lemma eq_refl: forall x, eq x x. + Proof. + unfold eq; destruct x; trivial. + apply L.eq_refl. + Qed. + + Lemma eq_sym: forall x y, eq x y -> eq y x. + Proof. + unfold eq; destruct x; destruct y; trivial. + apply L.eq_sym. + Qed. + + Lemma eq_trans: forall x y z, eq x y -> eq y z -> eq x z. + Proof. + unfold eq; destruct x; destruct y; destruct z; trivial. + - apply L.eq_trans. + - contradiction. + Qed. + + Definition beq (x y : t) := + match x, y with + | None, None => true + | Some x, Some y => L.beq x y + | Some _, None | None, Some _ => false + end. + + Lemma beq_correct: forall x y, beq x y = true -> eq x y. + Proof. + unfold beq, eq. + destruct x; destruct y; trivial; try congruence. + apply L.beq_correct. + Qed. + + Definition ge (x y : t) := + match x, y with + | None, Some _ => False + | _, None => True + | Some a, Some b => L.ge a b + end. + + Lemma ge_refl: forall x y, eq x y -> ge x y. + Proof. + unfold eq, ge. + destruct x; destruct y; trivial. + apply L.ge_refl. + Qed. + + Lemma ge_trans: forall x y z, ge x y -> ge y z -> ge x z. + Proof. + unfold ge. + destruct x; destruct y; destruct z; trivial; try contradiction. + apply L.ge_trans. + Qed. + + Definition bot: t := None. + Lemma ge_bot: forall x, ge x bot. + Proof. + unfold ge, bot. + destruct x; trivial. + Qed. + + Definition lub (a b : t) := + match a, b with + | None, _ => b + | _, None => a + | (Some x), (Some y) => Some (L.lub x y) + end. + + Lemma ge_lub_left: forall x y, ge (lub x y) x. + Proof. + unfold ge, lub. + destruct x; destruct y; trivial. + - apply L.ge_lub_left. + - apply L.ge_refl. + apply L.eq_refl. + Qed. + + Lemma ge_lub_right: forall x y, ge (lub x y) y. + Proof. + unfold ge, lub. + destruct x; destruct y; trivial. + - apply L.ge_lub_right. + - apply L.ge_refl. + apply L.eq_refl. + Qed. +End ADD_BOTTOM. + +Module RB := ADD_BOTTOM(RELATION). +Module DS := Dataflow_Solver(RB)(NodeSetForward). + +Definition kill_sym_val (dst : reg) (sv : sym_val) := + match sv with + | SMove src => if peq dst src then true else false + | SOp op args => List.existsb (peq dst) args + | SLoad chunk addr args => List.existsb (peq dst) args + end. + +Definition kill_reg (dst : reg) (rel : RELATION.t) := + PTree.filter1 (fun x => negb (kill_sym_val dst x)) + (PTree.remove dst rel). + +Definition kill_sym_val_mem (sv: sym_val) := + match sv with + | SMove _ => false + | SOp op _ => op_depends_on_memory op + | SLoad _ _ _ => true + end. + +Definition kill_mem (rel : RELATION.t) := + PTree.filter1 (fun x => negb (kill_sym_val_mem x)) rel. + + +Definition forward_move (rel : RELATION.t) (x : reg) : reg := + match rel ! x with + | Some (SMove org) => org + | _ => x + end. + +Definition move (src dst : reg) (rel : RELATION.t) := + PTree.set dst (SMove (forward_move rel src)) (kill_reg dst rel). + +Definition find_op_fold op args (already : option reg) x sv := + match already with + | Some found => already + | None => + match sv with + | (SOp op' args') => + if (eq_operation op op') && (eq_args args args') + then Some x + else None + | _ => None + end + end. + +Definition find_op (rel : RELATION.t) (op : operation) (args : list reg) := + PTree.fold (find_op_fold op args) rel None. + +Definition find_load_fold chunk addr args (already : option reg) x sv := + match already with + | Some found => already + | None => + match sv with + | (SLoad chunk' addr' args') => + if (chunk_eq chunk chunk') && + (eq_addressing addr addr') && + (eq_args args args') + then Some x + else None + | _ => None + end + end. + +Definition find_load (rel : RELATION.t) (chunk : memory_chunk) (addr : addressing) (args : list reg) := + PTree.fold (find_load_fold chunk addr args) rel None. + +Definition oper2 (op: operation) (dst : reg) (args : list reg) + (rel : RELATION.t) := + let rel' := kill_reg dst rel in + PTree.set dst (SOp op (List.map (forward_move rel') args)) rel'. + +Definition oper1 (op: operation) (dst : reg) (args : list reg) + (rel : RELATION.t) := + if List.in_dec peq dst args + then kill_reg dst rel + else oper2 op dst args rel. + +Definition oper (op: operation) (dst : reg) (args : list reg) + (rel : RELATION.t) := + match find_op rel op (List.map (forward_move rel) args) with + | Some r => move r dst rel + | None => oper1 op dst args rel + end. + +Definition gen_oper (op: operation) (dst : reg) (args : list reg) + (rel : RELATION.t) := + match op, args with + | Omove, src::nil => move src dst rel + | _, _ => oper op dst args rel + end. + +Definition load2 (chunk: memory_chunk) (addr : addressing) + (dst : reg) (args : list reg) (rel : RELATION.t) := + let rel' := kill_reg dst rel in + PTree.set dst (SLoad chunk addr (List.map (forward_move rel') args)) rel'. + +Definition load1 (chunk: memory_chunk) (addr : addressing) + (dst : reg) (args : list reg) (rel : RELATION.t) := + if List.in_dec peq dst args + then kill_reg dst rel + else load2 chunk addr dst args rel. + +Definition load (chunk: memory_chunk) (addr : addressing) + (dst : reg) (args : list reg) (rel : RELATION.t) := + match find_load rel chunk addr (List.map (forward_move rel) args) with + | Some r => move r dst rel + | None => load1 chunk addr dst args rel + end. + +(* NO LONGER NEEDED +Fixpoint list_represents { X : Type } (l : list (positive*X)) (tr : PTree.t X) : Prop := + match l with + | nil => True + | (r,sv)::tail => (tr ! r) = Some sv /\ list_represents tail tr + end. + +Lemma elements_represent : + forall { X : Type }, + forall tr : (PTree.t X), + (list_represents (PTree.elements tr) tr). +Proof. + intros. + generalize (PTree.elements_complete tr). + generalize (PTree.elements tr). + induction l; simpl; trivial. + intro COMPLETE. + destruct a as [ r sv ]. + split. + { + apply COMPLETE. + left; reflexivity. + } + apply IHl; auto. +Qed. +*) + +Definition apply_instr instr (rel : RELATION.t) : RB.t := + match instr with + | Inop _ + | Icond _ _ _ _ + | Ijumptable _ _ => Some rel + | Istore _ _ _ _ _ => Some (kill_mem rel) + | Iop op args dst _ => Some (gen_oper op dst args rel) + | Iload trap chunk addr args dst _ => Some (load chunk addr dst args rel) + | Icall _ _ _ dst _ => Some (kill_reg dst (kill_mem rel)) + | Ibuiltin _ _ res _ => Some (RELATION.top) (* TODO (kill_builtin_res res x) *) + | Itailcall _ _ _ | Ireturn _ => RB.bot + end. + +Definition apply_instr' code (pc : node) (ro : RB.t) : RB.t := + match ro with + | None => None + | Some x => + match code ! pc with + | None => RB.bot + | Some instr => apply_instr instr x + end + end. + +Definition forward_map (f : RTL.function) := DS.fixpoint + (RTL.fn_code f) RTL.successors_instr + (apply_instr' (RTL.fn_code f)) (RTL.fn_entrypoint f) (Some RELATION.top). + +Definition forward_move_b (rb : RB.t) (x : reg) := + match rb with + | None => x + | Some rel => forward_move rel x + end. + +Definition subst_arg (fmap : option (PMap.t RB.t)) (pc : node) (x : reg) : reg := + match fmap with + | None => x + | Some inv => forward_move_b (PMap.get pc inv) x + end. + +Definition subst_args fmap pc := List.map (subst_arg fmap pc). + +(* Transform *) +Definition find_op_in_fmap fmap pc op args := + match fmap with + | None => None + | Some map => + match PMap.get pc map with + | Some rel => find_op rel op args + | None => None + end + end. + +Definition find_load_in_fmap fmap pc chunk addr args := + match fmap with + | None => None + | Some map => + match PMap.get pc map with + | Some rel => find_load rel chunk addr args + | None => None + end + end. + +Definition transf_instr (fmap : option (PMap.t RB.t)) + (pc: node) (instr: instruction) := + match instr with + | Iop op args dst s => + let args' := subst_args fmap pc args in + match find_op_in_fmap fmap pc op args' with + | None => Iop op args' dst s + | Some src => Iop Omove (src::nil) dst s + end + | Iload trap chunk addr args dst s => + let args' := subst_args fmap pc args in + match find_load_in_fmap fmap pc chunk addr args' with + | None => Iload trap chunk addr args' dst s + | Some src => Iop Omove (src::nil) dst s + end + | Istore chunk addr args src s => + Istore chunk addr (subst_args fmap pc args) src s + | Icall sig ros args dst s => + Icall sig ros (subst_args fmap pc args) dst s + | Itailcall sig ros args => + Itailcall sig ros (subst_args fmap pc args) + | Icond cond args s1 s2 => + Icond cond (subst_args fmap pc args) s1 s2 + | Ijumptable arg tbl => + Ijumptable (subst_arg fmap pc arg) tbl + | Ireturn (Some arg) => + Ireturn (Some (subst_arg fmap pc arg)) + | _ => instr + end. + +Definition transf_function (f: function) : function := + {| fn_sig := f.(fn_sig); + fn_params := f.(fn_params); + fn_stacksize := f.(fn_stacksize); + fn_code := PTree.map (transf_instr (forward_map f)) f.(fn_code); + fn_entrypoint := f.(fn_entrypoint) |}. + + +Definition transf_fundef (fd: fundef) : fundef := + AST.transf_fundef transf_function fd. + +Definition transf_program (p: program) : program := + transform_program transf_fundef p. + +Definition match_prog (p tp: RTL.program) := + match_program (fun ctx f tf => tf = transf_fundef f) eq p tp. + +Lemma transf_program_match: + forall p, match_prog p (transf_program p). +Proof. + intros. eapply match_transform_program; eauto. +Qed. |