Minor modifications, adding comments

bin/miniFunInterpreter.ml

@@ -58,7 +58,8 @@ let () =
       | Lexer.LexingError msg ->
         Printf.fprintf stderr "%a: %s\n" print_position lexbuf msg;
         exit (-1)
-      | Parser.Error -> Printf.fprintf stderr "%a: syntax error\n" print_position lexbuf;
+      | Parser.Error ->
+        Printf.fprintf stderr "%a: syntax error\n" print_position lexbuf;
         exit (-1)
     in
     let _ =

bin/miniImpInterpreterReg.ml

@@ -5,7 +5,7 @@ open Lexing
 (*                             Command Arguments                              *)
 
 let () =
-  Clap.description "Interpreter for MiniImp language.";
+  Clap.description "Interpreter for MiniImp language to RISC code.";
 
   let files = Clap.section ~description: "Files to consider." "FILES" in
   let values = Clap.section ~description: "Input values." "VALUES" in
@@ -36,6 +36,22 @@ let () =
       false
   in
 
+  let checkundefined = Clap.flag
+      ~description: "Optional flag for disabling the check for undefined variables."
+      ~section: values
+      ~unset_long: "undefined"
+      ~unset_short: 'u'
+      true
+  in
+
+  let optimizereg = Clap.flag
+      ~description: "Optional flag for disabling optimizing registers with liveness analysis."
+      ~section: values
+      ~unset_long: "liveness"
+      ~unset_short: 'l'
+      true
+  in
+
   let inputval = Clap.default_int
       ~description: "Optional input value to feed to the program. \
                      If not specified it is read from stdin."
@@ -85,7 +101,7 @@ let () =
       CfgRISC.convert
     in
 
-    let () = (
+    if checkundefined then (
       match DefinedVariables.compute_defined_variables return_value |>
             DefinedVariables.check_undefined_variables
       with
@@ -94,13 +110,20 @@ let () =
         Printf.printf "Error: undefined variables: %a\n"
           DefinedVariables.Variable.pplist l;
         exit (-1)
-    ) in
+    ) else ();
 
     let return_value =
+      if optimizereg then
         return_value |>
         LiveVariables.compute_live_variables |>
         LiveVariables.optimize_cfg |>
-      LiveVariables.compute_cfg |>
+        LiveVariables.compute_cfg
+      else
+        return_value
+    in
+
+    let return_value =
+      return_value |>
       ReduceRegisters.reduceregisters registers |>
       RISC.convert
     in

lib/analysis/Dataflow.ml

@@ -41,7 +41,9 @@ module Make (M: Cfg.PrintableType) (I: Cfg.PrintableType) = struct
     match Utility.equality a.internalin b.internalin,
           Utility.equality a.internalout b.internalout,
           (List.fold_left2 (fun acc (ain, aout) (bin, bout)
-                            -> acc && (Utility.equality ain bin) && (Utility.equality aout bout)
+                             -> acc &&
+                                (Utility.equality ain bin) &&
+                                (Utility.equality aout bout)
             ) true a.internalbetween b.internalbetween)
     with
     | true, true, true -> true
@@ -54,7 +56,7 @@ module Make (M: Cfg.PrintableType) (I: Cfg.PrintableType) = struct
     internalvar: internalnode Cfg.NodeMap.t;
   }
 
-  let compareinternal (a: internalnode Cfg.NodeMap.t) (b: internalnode Cfg.NodeMap.t) =
+  let compareinternal a b =
     Cfg.NodeMap.fold
       (fun node bi acc ->
          match Cfg.NodeMap.find_opt node a with
@@ -141,7 +143,9 @@ module Make (M: Cfg.PrintableType) (I: Cfg.PrintableType) = struct
 
   let fixed_point
       ?(init : (elt list -> internalnode) =
-               (fun _ -> {internalin = []; internalout = []; internalbetween = []}))
+               (fun _ -> {internalin = [];
+                          internalout = [];
+                          internalbetween = []}))
       ?(update : (t -> Cfg.Node.t -> internalnode) =
                  (fun t n -> Cfg.NodeMap.find n t.internalvar))
       (t: t)
@@ -150,7 +154,7 @@ module Make (M: Cfg.PrintableType) (I: Cfg.PrintableType) = struct
        the update function takes the node and the whole structure and is
        expected to return the updated structure for the appropriate node,
        update function is applied to the resulting structure until no change is
-       observed
+       observed with compareinternal function
     *)
     let rec helper t =
       let newt =

lib/analysis/Dataflow.mli

@@ -18,7 +18,9 @@ module type C = sig
   val from_cfg : cfgt -> t
   val to_cfg : t -> cfgt
 
-  val fixed_point : ?init:(elt list -> internalnode) -> ?update:(t -> Cfg.Node.t -> internalnode) -> t -> t
+  val fixed_point :
+    ?init:(elt list -> internalnode) ->
+    ?update:(t -> Cfg.Node.t -> internalnode) -> t -> t
 
   val pp : out_channel -> t -> unit
 end

lib/miniFun/Lexer.mll

@@ -81,6 +81,7 @@ rule read = parse
               (lexbuf.Lexing.lex_curr_p.Lexing.pos_lnum)
               (lexbuf.Lexing.lex_curr_p.Lexing.pos_lnum)
            ))}
+
 and comments level = parse
   | "*)"    {if level = 0
              then read lexbuf

lib/miniFun/Parser.mly

@@ -24,7 +24,6 @@
 %start prg
 
 (* associativity in order of precedence *)
-/*%right rightlowest */
 %left lowest
 %right TYPEFUNCTION
 %left COMMA
@@ -35,7 +34,7 @@
 %left CMP CMPLESS CMPLESSEQ CMPGREATER CMPGREATEREQ
 %left PLUS MINUS
 %left TIMES DIVISION MODULO
-%left POWER
+%right POWER
 %right BNOT RAND
 %left FIRST SECOND
 %left LAMBDA

lib/miniImp/CfgImp.ml

@@ -25,7 +25,6 @@ module SimpleStatements = struct
     | SimpleDivision of simpleArithmetic * simpleArithmetic
     | SimpleModulo of simpleArithmetic * simpleArithmetic
     | SimplePower of simpleArithmetic * simpleArithmetic
-    | SimplePowerMod of simpleArithmetic * simpleArithmetic * simpleArithmetic
     | SimpleRand of simpleArithmetic
 
   let pp (ppf: out_channel) (c: t) : unit =
@@ -55,7 +54,6 @@ module SimpleStatements = struct
       | SimpleDivision (a1, a2) -> Printf.fprintf ppf "{%a / %a}" helper_a a1 helper_a a2
       | SimpleModulo (a1, a2) -> Printf.fprintf ppf "{%a %% %a}" helper_a a1 helper_a a2
       | SimplePower (a1, a2) -> Printf.fprintf ppf "{%a ^ %a}" helper_a a1 helper_a a2
-      | SimplePowerMod (a1, a2, a3) -> Printf.fprintf ppf "{powmod %a %a %a}" helper_a a1 helper_a a2 helper_a a3
       | SimpleRand (a) -> Printf.fprintf ppf "{rand %a}" helper_a a
     in
     helper_c ppf c
@@ -69,18 +67,19 @@ module SSCfg = Cfg.Make(SimpleStatements)
 let rec convert_c (prevcfg: SSCfg.t) (prg: Types.c_exp) : SSCfg.t =
   let open SimpleStatements in
   match prg with
-  | Skip ->
+  | Skip -> (* we preserve the skips *)
     prevcfg |> SSCfg.addToLastNode SimpleSkip
 
-  | Assignment (x, a) ->
+  | Assignment (x, a) -> (* we simply add the assignment to the terminal node *)
     prevcfg |> SSCfg.addToLastNode (SimpleAssignment (x, convert_a a))
 
-  | Sequence (c1, c2) ->
+  | Sequence (c1, c2) -> (* we first convert the first sequence, then the second
+                            using the previous as prevcfg *)
     let cfg1 = convert_c prevcfg c1 in
     let cfg2 = convert_c cfg1 c2 in
     cfg2
 
-  | If (b, c1, c2) ->
+  | If (b, c1, c2) -> (* constructs two branches with a two new nodes *)
     let convertedb = convert_b b in
     let cfg1 = convert_c SSCfg.empty c1 in
     let cfg2 = convert_c SSCfg.empty c2 in
@@ -93,7 +92,7 @@ let rec convert_c (prevcfg: SSCfg.t) (prg: Types.c_exp) : SSCfg.t =
                 NodeMap.add_to_list entrynode (SimpleGuard convertedb) |>
                 NodeMap.add_to_list exitnode (SimpleSkip) }
 
-  | While (b, c) ->
+  | While (b, c) -> (* constructs a loop, needs three new nodes *)
     let convertedb = convert_b b in
     let cfg = convert_c SSCfg.empty c in
     let cfginitial = Option.get cfg.initial in
@@ -124,7 +123,8 @@ let rec convert_c (prevcfg: SSCfg.t) (prg: Types.c_exp) : SSCfg.t =
                 NodeMap.add_to_list exitnode (SimpleSkip)
     } |> SSCfg.concat prevcfg
 
-  | For (assignment, guard, increment, body) ->
+  | For (assignment, guard, increment, body) -> (* constructs a loop, needs
+                                                   two new nodes *)
     let cfgassignment = convert_c SSCfg.empty assignment in
     let convertedguard = convert_b guard in
     let cfgincrement = convert_c SSCfg.empty increment in

lib/miniImp/CfgImp.mli

@@ -24,7 +24,6 @@ module SimpleStatements : sig
     | SimpleDivision of simpleArithmetic * simpleArithmetic
     | SimpleModulo of simpleArithmetic * simpleArithmetic
     | SimplePower of simpleArithmetic * simpleArithmetic
-    | SimplePowerMod of simpleArithmetic * simpleArithmetic * simpleArithmetic
     | SimpleRand of simpleArithmetic
 
   val pp : out_channel -> t -> unit

lib/miniImp/CfgRISC.ml

@@ -706,9 +706,6 @@ and c_ss_sa
           (convertedcode @ [BRegOp (Pow, partialresreg1, partialresreg2, register)], m)
         )
     )
-  | SimplePowerMod (_a1, _a2, _a3) -> (
-      failwith "not implemented"
-    )
   | SimpleRand (a) -> (
       let partialresreg, m, _partialresvar = RegisterMap.get_fresh_register m in
       let convertedcode, m = c_ss_sa a m convertedcode partialresreg in

lib/miniImp/Parser.mly

@@ -32,7 +32,7 @@
 %left DIVISION
 %left MODULO
 %left TIMES
-%left POWER
+%right POWER
 %left DO
 
 %%

lib/miniImp/RISCSemantics.ml

@@ -19,6 +19,8 @@ module RISCArchitecture = struct
 end
 
 let convert (prg: RISC.RISCAssembly.t) : RISC.RISCAssembly.risci list CodeMap.t =
+  (* takes as input a sequence of RISC commands and computes a map to the right
+     labels for easier execution *)
   let rec helper
       (prg: RISC.RISCAssembly.risci list)
       (current: RISC.RISCAssembly.risci list)
@@ -98,7 +100,8 @@ let reduce_instructions (prg: RISCArchitecture.t) (lo: string list) : int =
           None -> prg (* should never happen *)
         | Some i ->
           if i + 1 < (List.length lo) then
-            helper prg (CodeMap.find (List.nth lo (i+1)) prg.code) (List.nth lo (i+1))
+            helper
+              prg (CodeMap.find (List.nth lo (i+1)) prg.code) (List.nth lo (i+1))
           else
             prg
       )
@@ -109,32 +112,45 @@ let reduce_instructions (prg: RISCArchitecture.t) (lo: string list) : int =
             (RegisterMap.find {index = r1.index} prg.registers)
             (RegisterMap.find {index = r2.index} prg.registers)
         in
-        helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+        helper { prg with
+                 registers = RegisterMap.add {index = r3.index} n prg.registers }
+          tl current_label
       )
     | BImmOp (biop, r1, i, r3) :: tl -> (
         let n = (match_operator_i biop)
             (RegisterMap.find {index = r1.index} prg.registers)
             i
         in
-        helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+        helper { prg with
+                 registers = RegisterMap.add {index = r3.index} n prg.registers }
+          tl current_label
       )
     | URegOp (urop, r1, r3) :: tl -> (
         match urop with
         | Copy -> (
             let n = RegisterMap.find {index = r1.index} prg.registers in
-            helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+            helper { prg with
+                     registers =
+                       RegisterMap.add {index = r3.index} n prg.registers }
+              tl current_label
           )
         | Not -> (
             let n = Utility.int_not
                 (RegisterMap.find {index = r1.index} prg.registers)
             in
-            helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+            helper { prg with
+                     registers =
+                       RegisterMap.add {index = r3.index} n prg.registers }
+              tl current_label
           )
         | Rand -> (
             let n = Random.int
                 (RegisterMap.find {index = r1.index} prg.registers)
             in
-            helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+            helper { prg with
+                     registers =
+                       RegisterMap.add {index = r3.index} n prg.registers }
+              tl current_label
           )
       )
     | Load (r1, r3) :: tl -> (
@@ -143,12 +159,16 @@ let reduce_instructions (prg: RISCArchitecture.t) (lo: string list) : int =
             (RegisterMap.find {index = r1.index} prg.registers)
             prg.memory
         in
-        helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+        helper { prg with
+                 registers = RegisterMap.add {index = r3.index} n prg.registers }
+          tl current_label
       )
     | LoadI (i, r3) :: tl -> (
         let n = i
         in
-        helper {prg with registers = RegisterMap.add {index = r3.index} n prg.registers} tl current_label
+        helper { prg with
+                 registers = RegisterMap.add {index = r3.index} n prg.registers }
+          tl current_label
       )
     | Store (r1, r3) :: tl -> (
         let n = RegisterMap.find {index = r1.index} prg.registers in
@@ -166,12 +186,17 @@ let reduce_instructions (prg: RISCArchitecture.t) (lo: string list) : int =
       )
     | Label _ :: tl -> helper prg tl current_label
   in
-  RegisterMap.find
+  match
+    RegisterMap.find_opt
       prg.outputreg
       (helper prg (CodeMap.find "main" prg.code) "main").registers
+  with
+    Some x -> x
+  | None -> failwith "Output register not found"
 
 
 let reduce (prg: RISC.RISCAssembly.t) : int =
+  (* takes assembly and execute it *)
   reduce_instructions
     {code = convert prg;
      registers = (

lib/miniImp/definedVariables.ml

@@ -191,6 +191,7 @@ let update (t: DVCfg.t) (node: Cfg.Node.t) : DVCfg.internalnode =
 
 
 let compute_defined_variables (cfg: RISCCfg.t) : DVCfg.t =
+  (* creates the DVCfg structure and finds the fixed point *)
   let all_variables = List.fold_left
       (fun acc (_, code) ->
          Utility.unique_union acc (variables_all code))
@@ -208,6 +209,7 @@ let compute_defined_variables (cfg: RISCCfg.t) : DVCfg.t =
 
 
 let check_undefined_variables (dvcfg: DVCfg.t) : Variable.t list option =
+  (* returns all undefined variables previously computed *)
   let helper (node: Cfg.Node.t) (dvcfg: DVCfg.t) : Variable.t list option =
     let code = match Cfg.NodeMap.find_opt node dvcfg.t.content with
         None -> []
@@ -257,4 +259,5 @@ let check_undefined_variables (dvcfg: DVCfg.t) : Variable.t list option =
 
 
 let compute_cfg (dvcfg: DVCfg.t) : RISCCfg.t =
+  (* no change to the cfg so returned as is *)
   DVCfg.to_cfg dvcfg

lib/miniImp/liveVariables.ml

@@ -238,14 +238,14 @@ let optimize_cfg (t: DVCfg.t) : DVCfg.t =
     (newassignments, newt)
   in
 
-  (* --------- *)
+  (* ------------------- *)
 
   let assignments = VariableMap.empty in
 
   let a, newt =
     Cfg.NodeSet.fold (* for each node we replace all the variables with the
                         optimized ones *)
-      (fun node (ass, t) -> aux ass t node)
+      (fun node (assign, t) -> aux assign t node)
       t.t.nodes
       (assignments, t)
   in

lib/miniImp/reduceRegisters.ml

@@ -18,7 +18,8 @@ module RISCCfg = CfgRISC.RISCCfg
 module VariableMap = Map.Make(Variable)
 
 let variables_frequency (instr : RISCCfg.elt) : (Variable.t * int) list =
-  let add_one = (fun x -> match x with None -> Some 1 | Some x -> Some (x + 1)) in
+  let add_one = (fun x -> match x with None -> Some 1 | Some x -> Some (x + 1))
+  in
 
   let helper (acc: int VariableMap.t) (instr: RISCCfg.elt) : int VariableMap.t =
     match instr with
@@ -40,7 +41,9 @@ let variables_frequency (instr : RISCCfg.elt) : (Variable.t * int) list =
 
   helper VariableMap.empty instr |> VariableMap.to_list
 
-let variables_all_frequency (instructions : RISCCfg.elt list) : (Variable.t * int) list =
+(* computes syntactic frequency of all variables in the code *)
+let variables_all_frequency (instructions : RISCCfg.elt list)
+  : (Variable.t * int) list =
   List.fold_left
     ( fun (acc: int VariableMap.t) (instr: RISCCfg.elt) ->
         VariableMap.union
@@ -50,16 +53,20 @@ let variables_all_frequency (instructions : RISCCfg.elt list) : (Variable.t * in
 
 
 let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
-  (if n < 4 then (failwith "ReduceRegisters: number of registers too small") else ());
+  (if n < 4 then (
+      failwith "ReduceRegisters: number of registers too small"
+    ) else ());
 
   (* we get all the variables with associated frequency (only syntactic use) *)
   let all_variables = List.fold_left
       (fun acc (_, code) ->
-         Utility.unique_union_assoc (fun _n x y -> x + y) acc (variables_all_frequency code))
+         Utility.unique_union_assoc
+           (fun _n x y -> x + y) acc (variables_all_frequency code))
       []
       (Cfg.NodeMap.to_list cfg.content)
   in
 
+  (* add one to in and out variables *)
   let all_variables =
     match cfg.inputOutputVar with
     | None -> all_variables
@@ -80,6 +87,8 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
     )
   in
 
+  (* replace each operation with a list of operations that have the new
+     registers or load from memory *)
   let replaceregisters
       (remappedregisters: Variable.t VariableMap.t)
       (memorymap: int VariableMap.t)
@@ -143,7 +152,10 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
              BRegOp (brop, tmpreg1, tmpreg2, tmpreg2);
              LoadI (m3, tmpreg1);
              Store (tmpreg2, tmpreg1)]
-          | _ -> [BRegOp (brop, {index = r1.index}, {index = r2.index}, {index = r3.index})]
+          | _ -> [BRegOp (brop,
+                          {index = r1.index},
+                          {index = r2.index},
+                          {index = r3.index})]
         )
       | BImmOp (biop, r1, i, r3) -> (
           match ( VariableMap.find_opt r1.index remappedregisters,
@@ -237,8 +249,8 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
                            " registers have no binding.")
         )
       | Store (r1, r3) -> (
-          (* we want to maybe store an address in memory (very confusing, don't
+          (* we want to maybe store an address in memory (very confusing,
-             think can happen) *)
+             but maybe possible) *)
           match ( VariableMap.find_opt r1.index remappedregisters,
                   VariableMap.find_opt r3.index remappedregisters,
                   VariableMap.find_opt r1.index memorymap,
@@ -269,6 +281,8 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
   in
 
 
+  (* partition the variables into two sets, most frequent and least frequent
+     then apply the transformation *)
   let aux (cfg: RISCCfg.t) (all_variables: (string * int) list) =
     (* we keep the first two variables free for immediate use *)
     let most_frequent, least_frequent =
@@ -298,8 +312,13 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
     let newcfg = {
       cfg with
       content = Cfg.NodeMap.map
-          (fun x -> replaceregisters most_frequent_mapping least_frequent_mapping ["1"; "2"] x)
+          ( fun x ->
-          cfg.content}
+              replaceregisters
+                most_frequent_mapping
+                least_frequent_mapping
+                ["1"; "2"]
+                x
+          ) cfg.content}
     in
 
     match newcfg.inputOutputVar with
@@ -417,7 +436,6 @@ let reduceregisters (n: int) (cfg: RISCCfg.t) : RISCCfg.t =
       )
   in
 
-
   ( if List.length all_variables <= n
     then cfg
     else aux cfg all_variables )

lib/miniImp/replacePowerMod.ml

@@ -1,10 +1,8 @@
 let rewrite_instructions (prg: Types.p_exp) : Types.p_exp =
   (* function takes a program and replaces all occurrences of powermod with
      simpler instructions *)
-  let i, o, prg = (
+
-    match prg with
+  let Main (i, o, prg) = prg in
-    | Main (i, o, exp) -> i, o, exp
-  ) in
 
   let rec contains_rewrite (prg: Types.c_exp) : Types.a_exp option =
     (* if the ast contains powermod anywhere returns the powermod, otherwise