1 files changed, 53 insertions, 389 deletions

diff --git a/backend/Linearizeaux.ml b/backend/Linearizeaux.ml
index 3f1a8b6e..5914f6a3 100644
--- a/backend/Linearizeaux.ml
+++ b/backend/Linearizeaux.ml
@@ -126,400 +126,64 @@ let enumerate_aux_flat f reach =
  * This is a slight alteration to the above heuristic, ensuring that any
  * superblock will be contiguous in memory, while still following the original
  * heuristic
+ *
+ * Slight change: instead of taking the minimum pc of the superblock, we just take
+ * the pc of the first block.
+ * (experimentally this leads to slightly better performance..)
  *)
 
-let get_some = function
-| None -> failwith "Did not get some"
-| Some thing -> thing
-
-exception EmptyList
-
-let rec last_element = function
-  | [] -> raise EmptyList
-  | e :: [] -> e
-  | e' :: e :: l -> last_element (e::l)
-
-let print_plist l =
-  let rec f = function
-  | [] -> ()
-  | n :: l -> Printf.printf "%d, " (P.to_int n); f l
-  in begin
-    if !debug_flag then begin
-      Printf.printf "[";
-      f l;
-      Printf.printf "]"
-    end
-  end
-
-(* adapted from the above join_points function, but with PTree *)
-let get_join_points code entry =
-  let reached = ref (PTree.map (fun n i -> false) code) in
-  let reached_twice = ref (PTree.map (fun n i -> false) code) in
-  let rec traverse pc =
-    if get_some @@ PTree.get pc !reached then begin
-      if not (get_some @@ PTree.get pc !reached_twice) then
-        reached_twice := PTree.set pc true !reached_twice
-    end else begin
-      reached := PTree.set pc true !reached;
-      traverse_succs (successors_block @@ get_some @@ PTree.get pc code)
-    end
-  and traverse_succs = function
-    | [] -> ()
-    | [pc] -> traverse pc
-    | pc :: l -> traverse pc; traverse_succs l
-  in traverse entry; !reached_twice
-
-let forward_sequences code entry =
-  let visited = ref (PTree.map (fun n i -> false) code) in
-  let join_points = get_join_points code entry in
-  (* returns the list of traversed nodes, and a list of nodes to start traversing next *)
-  let rec traverse_fallthrough code node =
-    (* debug "Traversing %d..\n" (P.to_int node); *)
-    if not (get_some @@ PTree.get node !visited) then begin
-      visited := PTree.set node true !visited;
-      match PTree.get node code with
-      | None -> failwith "No such node"
-      | Some bb ->
-          let ln, rem = match (last_element bb) with
-          | Lop _ | Lload _ | Lgetstack _ | Lsetstack _ | Lstore _ | Lcall _
-          | Lbuiltin _ -> assert false
-          | Ltailcall _ | Lreturn -> begin (* debug "STOP tailcall/return\n"; *) ([], []) end
-          | Lbranch n ->
-              if get_some @@ PTree.get n join_points then ([], [n])
-              else let ln, rem = traverse_fallthrough code n in (ln, rem)
-          | Lcond (_, _, ifso, ifnot, info) -> (match info with
-            | None -> begin (* debug "STOP Lcond None\n"; *) ([], [ifso; ifnot]) end
-            | Some false ->
-                if get_some @@ PTree.get ifnot join_points then ([], [ifso; ifnot])
-                else let ln, rem = traverse_fallthrough code ifnot in (ln, [ifso] @ rem)
-            | Some true ->
-                if get_some @@ PTree.get ifso join_points then ([], [ifso; ifnot])
-                else let ln, rem = traverse_fallthrough code ifso in (ln, [ifnot] @ rem)
-            )
-          | Ljumptable(_, ln) -> begin (* debug "STOP Ljumptable\n"; *) ([], ln) end
-          in ([node] @ ln, rem)
-      end
-    else ([], [])
-  in let rec f code = function
-  | [] -> []
-  | node :: ln ->
-      let fs, rem_from_node = traverse_fallthrough code node
-      in [fs] @ ((f code rem_from_node) @ (f code ln))
-  in (f code [entry])
-
-(** Unused code
-module PInt = struct
-  type t = P.t
-  let compare x y = compare (P.to_int x) (P.to_int y)
-end
-
-module PSet = Set.Make(PInt)
-
-module LPInt = struct
-  type t = P.t list
-  let rec compare x y =
-    match x with
-    | [] -> ( match y with
-      | [] -> 0
-      | _ -> 1 )
-    | e :: l -> match y with
-      | [] -> -1
-      | e' :: l' ->
-          let e_cmp = PInt.compare e e' in
-          if e_cmp == 0 then compare l l' else e_cmp
-end
-
-module LPSet = Set.Make(LPInt)
-
-let iter_lpset f s = Seq.iter f (LPSet.to_seq s)
-
-let first_of = function
-  | [] -> None
-  | e :: l -> Some e
-
-let rec last_of = function
-  | [] -> None
-  | e :: l -> (match l with [] -> Some e | e :: l -> last_of l)
-
-let can_be_merged code s s' =
-  let last_s = get_some @@ last_of s in
-  let first_s' = get_some @@ first_of s' in
-  match get_some @@ PTree.get last_s code with
-  | Lop _ | Lload _ | Lgetstack _ | Lsetstack _ | Lstore _ | Lcall _
-  | Lbuiltin _ | Ltailcall _ | Lreturn -> false
-  | Lbranch n -> n == first_s'
-  | Lcond (_, _, ifso, ifnot, info) -> (match info with
-    | None -> false
-    | Some false -> ifnot == first_s'
-    | Some true -> failwith "Inconsistency detected - ifnot is not the preferred branch")
-  | Ljumptable (_, ln) ->
-      match ln with
-      | [] -> false
-      | n :: ln -> n == first_s'
-
-let merge s s' = Some s
-
-let try_merge code (fs: (BinNums.positive list) list) =
-  let seqs = ref (LPSet.of_list fs) in
-  let oldLength = ref (LPSet.cardinal !seqs) in
-  let continue = ref true in
-  let found = ref false in
-  while !continue do
-    begin
-      found := false;
-      iter_lpset (fun s ->
-        if !found then ()
-        else iter_lpset (fun s' ->
-          if (!found || s == s') then ()
-          else if (can_be_merged code s s') then
-            begin
-              seqs := LPSet.remove s !seqs;
-              seqs := LPSet.remove s' !seqs;
-              seqs := LPSet.add (get_some (merge s s')) !seqs;
-              found := true;
-            end
-          else ()
-        ) !seqs
-      ) !seqs;
-      if !oldLength == LPSet.cardinal !seqs then
-        continue := false
-      else
-        oldLength := LPSet.cardinal !seqs
-    end
-  done;
-  !seqs
-*)
-
-(** Code adapted from Duplicateaux.get_loop_headers
-  *
-  * Getting loop branches with a DFS visit :
-  * Each node is either Unvisited, Visited, or Processed
-  * pre-order: node becomes Processed
-  * post-order: node becomes Visited
-  *
-  * If we come accross an edge to a Processed node, it's a loop!
-  *)
-type pos = BinNums.positive
-
-module PP = struct
-  type t = pos * pos
-  let compare a b =
-    let ax, ay = a in
-    let bx, by = b in
-    let dx = compare ax bx in
-    if (dx == 0) then compare ay by
-    else dx
-end
-
-module PPMap = Map.Make(PP)
-
-type vstate = Unvisited | Processed | Visited
-
-let get_loop_edges code entry =
-  let visited = ref (PTree.map (fun n i -> Unvisited) code) in
-  let is_loop_edge = ref PPMap.empty
-  in let rec dfs_visit code from = function
-  | [] -> ()
-  | node :: ln ->
-      match (get_some @@ PTree.get node !visited) with
-      | Visited -> ()
-      | Processed -> begin
-          let from_node = get_some from in
-          is_loop_edge := PPMap.add (from_node, node) true !is_loop_edge;
-          visited := PTree.set node Visited !visited
-        end
-      | Unvisited -> begin
-          visited := PTree.set node Processed !visited;
-          let bb = get_some @@ PTree.get node code in
-          let next_visits = (match (last_element bb) with
-          | Lop _ | Lload _ | Lgetstack _ | Lsetstack _ | Lstore _ | Lcall _
-          | Lbuiltin _ -> assert false
-          | Ltailcall _ | Lreturn -> []
-          | Lbranch n -> [n]
-          | Lcond (_, _, ifso, ifnot, _) -> [ifso; ifnot]
-          | Ljumptable(_, ln) -> ln
-          ) in dfs_visit code (Some node) next_visits;
-          visited := PTree.set node Visited !visited;
-          dfs_visit code from ln
-        end
-  in begin
-    dfs_visit code None [entry];
-    !is_loop_edge
-  end
-
-let ppmap_is_true pp ppmap = PPMap.mem pp ppmap && PPMap.find pp ppmap
-
-module Int = struct
-  type t = int
-  let compare x y = compare x y
-end
-
-module ISet = Set.Make(Int)
-
-let print_iset s = begin
-  if !debug_flag then begin
-    Printf.printf "{";
-    ISet.iter (fun e -> Printf.printf "%d, " e) s;
-    Printf.printf "}"
-  end
-end
-
-let print_depmap dm = begin
-  if !debug_flag then begin
-    Printf.printf "[|";
-    Array.iter (fun s -> print_iset s; Printf.printf ", ") dm;
-    Printf.printf "|]\n"
-  end
-end
-
-let construct_depmap code entry fs =
-  let is_loop_edge = get_loop_edges code entry in
-  let visited = ref (PTree.map (fun n i -> false) code) in
-  let depmap = Array.map (fun e -> ISet.empty) fs in
-  let find_index_of_node n =
-    let index = ref 0 in
-    begin
-      Array.iteri (fun i s ->
-        match List.find_opt (fun e -> e == n) s with
-        | Some _ -> index := i
-        | None -> ()
-      ) fs;
-      !index
-    end
-  in let check_and_update_depmap from target =
-    (* debug "From %d to %d\n" (P.to_int from) (P.to_int target); *)
-    if not (ppmap_is_true (from, target) is_loop_edge) then
-      let in_index_fs = find_index_of_node from in
-      let out_index_fs = find_index_of_node target in
-      if out_index_fs != in_index_fs then
-        depmap.(out_index_fs) <- ISet.add in_index_fs depmap.(out_index_fs)
-      else ()
-    else ()
-  in let rec dfs_visit code = function
-  | [] -> ()
-  | node :: ln ->
-      begin
-        match (get_some @@ PTree.get node !visited) with
-        | true -> ()
-        | false -> begin
-            visited := PTree.set node true !visited;
-            let bb = get_some @@ PTree.get node code in
-            let next_visits =
-              match (last_element bb) with
-              | Ltailcall _ | Lreturn -> []
-              | Lbranch n -> (check_and_update_depmap node n; [n])
-              | Lcond (_, _, ifso, ifnot, _) -> begin
-                  check_and_update_depmap node ifso;
-                  check_and_update_depmap node ifnot;
-                  [ifso; ifnot]
-                end
-              | Ljumptable(_, ln) -> begin
-                  List.iter (fun n -> check_and_update_depmap node n) ln;
-                  ln
-                end
-              (* end of bblocks should not be another value than one of the above *)
-              | _ -> failwith "last_element gave an invalid output"
-            in dfs_visit code next_visits
-          end;
-        dfs_visit code ln
-      end
-  in begin
-    dfs_visit code [entry];
-    depmap
-  end
-
-let print_sequence s =
-  if !debug_flag then begin
-    Printf.printf "[";
-    List.iter (fun n -> Printf.printf "%d, " (P.to_int n)) s;
-    Printf.printf "]\n"
-  end
-
-let print_ssequence ofs =
-  if !debug_flag then begin
-    Printf.printf "[";
-    List.iter (fun s -> print_sequence s) ofs;
-    Printf.printf "]\n"
-  end
-
-let order_sequences code entry fs =
-  let fs_a = Array.of_list fs in
-  let depmap = construct_depmap code entry fs_a in
-  let fs_evaluated = Array.map (fun e -> false) fs_a in
-  let ordered_fs = ref [] in
-  let evaluate s_id =
-    begin
-      assert (not fs_evaluated.(s_id));
-      ordered_fs := fs_a.(s_id) :: !ordered_fs;
-      fs_evaluated.(s_id) <- true;
-      (* debug "++++++\n";
-      debug "Scheduling %d\n" s_id;
-      debug "Initial depmap: "; print_depmap depmap; *)
-      Array.iteri (fun i deps ->
-        depmap.(i) <- ISet.remove s_id deps
-      ) depmap;
-      (* debug "Final depmap: "; print_depmap depmap; *)
+let super_blocks f joins =
+  let blocks = ref [] in
+  let visited = ref IntSet.empty in
+  (* start_block:
+       pc is the function entry point
+          or a join point
+          or the successor of a conditional test *)
+  let rec start_block pc =
+    let npc = P.to_int pc in
+    if not (IntSet.mem npc !visited) then begin
+      visited := IntSet.add npc !visited;
+      in_block [] npc pc
     end
-  in let choose_best_of candidates =
-    let current_best_id = ref None in
-    let current_best_score = ref None in
-    begin
-      List.iter (fun id ->
-        match !current_best_id with
-        | None -> begin
-            current_best_id := Some id;
-            match fs_a.(id) with
-            | [] -> current_best_score := None
-            | n::l -> current_best_score := Some (P.to_int n)
-          end
-        | Some b -> begin
-            match fs_a.(id) with
-            | [] -> ()
-            | n::l -> let nscore = P.to_int n in
-              match !current_best_score with
-              | None -> (current_best_id := Some id; current_best_score := Some nscore)
-              | Some bs -> if nscore > bs then (current_best_id := Some id; current_best_score := Some nscore)
+  (* in_block: add pc to block and check successors *)
+  and in_block blk minpc pc =
+    let blk = pc :: blk in
+    match PTree.get pc f.fn_code with
+    | None -> assert false
+    | Some b ->
+       let rec do_instr_list = function
+       | [] -> assert false
+       | Lbranch s :: _ -> next_in_block blk minpc s
+       | Ltailcall (sig0, ros) :: _ -> end_block blk minpc
+       | Lcond (cond, args, ifso, ifnot, pred) :: _ -> begin
+            match pred with
+            | None -> (end_block blk minpc; start_block ifso; start_block ifnot)
+            | Some true -> (next_in_block blk minpc ifso; start_block ifnot)
+            | Some false -> (next_in_block blk minpc ifnot; start_block ifso)
           end
-      ) candidates;
-      !current_best_id
-    end
-  in let select_next () =
-    let candidates = ref [] in
-    begin
-      Array.iteri (fun i deps ->
-        begin
-          (* debug "Deps of %d: " i; print_iset deps; debug "\n"; *)
-          (* FIXME - if we keep it that way (no dependency check), remove all the unneeded stuff *)
-          if ((* deps == ISet.empty && *) not fs_evaluated.(i)) then
-            candidates := i :: !candidates
-        end
-      ) depmap;
-      if not (List.length !candidates > 0) then begin
-        Array.iteri (fun i deps ->
-          if (not fs_evaluated.(i)) then candidates := i :: !candidates
-        ) depmap;
-      end;
-      get_some (choose_best_of !candidates)
-    end
-  in begin
-    debug "-------------------------------\n";
-    debug "depmap: "; print_depmap depmap;
-    debug "forward sequences identified: "; print_ssequence fs;
-    while List.length !ordered_fs != List.length fs do
-      let next_id = select_next () in
-      evaluate next_id
-    done;
-    debug "forward sequences ordered: "; print_ssequence (List.rev (!ordered_fs));
-    List.rev (!ordered_fs)
-  end
+       | Ljumptable(arg, tbl) :: _ ->
+             end_block blk minpc; List.iter start_block tbl
+       | Lreturn :: _ -> end_block blk minpc
+       | instr :: b' -> do_instr_list b' in
+       do_instr_list b
+  (* next_in_block: check if join point and either extend block
+     or start block *)
+  and next_in_block blk minpc pc =
+    let npc = P.to_int pc in
+    if IntSet.mem npc joins
+    then (end_block blk minpc; start_block pc)
+    else in_block blk minpc pc
+  (* end_block: record block that we just discovered *)
+  and end_block blk minpc =
+    blocks := (minpc, List.rev blk) :: !blocks
+  in
+    start_block f.fn_entrypoint; !blocks
+
+(* Build the enumeration *)
 
-let enumerate_aux_trace f reach =
-  let code = f.fn_code in
-  let entry = f.fn_entrypoint in
-  let fs = forward_sequences code entry in
-  let ofs = order_sequences code entry fs in
-  List.flatten ofs
+let enumerate_aux_sb f reach =
+  flatten_blocks (super_blocks f (join_points f))
 
 let enumerate_aux f reach =
-  if !Clflags.option_ftracelinearize then enumerate_aux_trace f reach
+  if !Clflags.option_ftracelinearize then enumerate_aux_sb f reach
   else enumerate_aux_flat f reach