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[diderot] Annotation of /trunk/src/compiler/simplify/simplify.sml
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Annotation of /trunk/src/compiler/simplify/simplify.sml

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1 : jhr 171 (* simplify.sml
2 :     *
3 :     * COPYRIGHT (c) 2010 The Diderot Project (http://diderot.cs.uchicago.edu)
4 :     * All rights reserved.
5 :     *
6 :     * Simplify the AST representation.
7 :     *)
8 :    
9 :     structure Simplify : sig
10 :    
11 :     val transform : AST.program -> Simple.program
12 :    
13 :     end = struct
14 :    
15 :     structure Ty = Types
16 :     structure S = Simple
17 :    
18 :     local
19 :     val tempName = Atom.atom "_t"
20 :     in
21 :     fun newTemp ty = Var.new (tempName, AST.LocalVar, ty)
22 :     end
23 :    
24 :     (* make a block out of a list of statements that are in reverse order *)
25 :     fun mkBlock stms = let
26 :     fun flatten [] = []
27 :     | flatten (S.S_Block stms :: r) = stms @ flatten r
28 :     | flatten (stm :: r) = stm :: flatten r
29 :     in
30 :     S.S_Block(flatten (List.rev stms))
31 :     end
32 :    
33 :     fun transform (AST.Program dcls) = let
34 :     val globals = ref []
35 :     val globalInit = ref []
36 :     val actors = ref []
37 :     fun simplifyDecl dcl = (case dcl
38 :     of AST.D_Input(x, NONE) => globals := x :: !globals
39 :     | AST.D_Input(x, SOME e) => let
40 :     val (stms, e') = simplifyExp (e, [])
41 :     in
42 :     (* FIXME: note that we should add code to check for the input value overriding the default value *)
43 :     globals := x :: !globals;
44 :     globalInit := S.S_Assign(x, e') :: (stms @ !globalInit)
45 :     end
46 :     | AST.D_Var(AST.VD_Decl(x, e)) => let
47 :     val (stms, e') = simplifyExp (e, [])
48 :     in
49 :     globals := x :: !globals;
50 :     globalInit := S.S_Assign(x, e') :: (stms @ !globalInit)
51 :     end
52 :     | AST.D_Actor info => actors := simplifyActor info :: !actors
53 :     | AST.D_InitialArray(e, iters) => () (* FIXME *)
54 :     | AST.D_InitialCollection(e, iters) => () (* FIXME *)
55 :     (* end case *))
56 :     in
57 :     List.app simplifyDecl dcls;
58 :     S.Prog{
59 :     globals = List.rev(!globals),
60 :     globalInit = mkBlock (!globalInit),
61 :     actors = List.rev(!actors)
62 :     }
63 :     end
64 :    
65 :     and simplifyActor {name, params, state, methods} = let
66 :     fun simplifyState ([], xs, stms) = (List.rev xs, mkBlock stms)
67 :     | simplifyState (AST.VD_Decl(x, e) :: r, xs, stms) = let
68 :     val (stms, e') = simplifyExp (e, stms)
69 :     in
70 :     simplifyState (r, x::xs, S.S_Assign(x, e') :: stms)
71 :     end
72 :     val (xs, stm) = simplifyState (state, [], [])
73 :     in
74 :     S.Actor{
75 :     params = params,
76 :     state = xs, stateInit = stm,
77 :     methods = List.map simplifyMethod methods
78 :     }
79 :     end
80 :    
81 :     and simplifyMethod (AST.M_Method(name, body)) =
82 :     S.M_Method(name, simplifyBlock body)
83 :    
84 :     (* simplify a statement into a single statement (i.e., a block if it expands into more
85 :     * than one new statement.
86 :     *)
87 :     and simplifyBlock stm = mkBlock (simplifyStmt (stm, []))
88 :    
89 :     and simplifyStmt (stm, stms) = (case stm
90 :     of AST.S_Block body => let
91 :     fun simplify ([], stms) = stms
92 :     | simplify (stm::r, stms) = simplify (r, simplifyStmt (stm, stms))
93 :     in
94 :     simplify (body, stms)
95 :     end
96 :     | AST.S_Decl(AST.VD_Decl(x, e)) => let
97 :     val (stms, e') = simplifyExp (e, stms)
98 :     in
99 :     S.S_Assign(x, e') :: stms
100 :     end
101 :     | AST.S_IfThenElse(e, s1, s2) => let
102 :     val (stms, x) = simplifyExpToVar (e, stms)
103 :     val s1 = simplifyBlock s1
104 :     val s2 = simplifyBlock s2
105 :     in
106 :     S.S_IfThenElse(x, s1, s2) :: stms
107 :     end
108 :     | AST.S_Assign(x, e) => let
109 :     val (stms, e') = simplifyExp (e, stms)
110 :     in
111 :     S.S_Assign(x, e') :: stms
112 :     end
113 :     | AST.S_New(name, args) => let
114 :     val (stms, xs) = simplifyExpsToVars (args, stms)
115 :     in
116 :     S.S_New(name, xs) :: stms
117 :     end
118 :     | AST.S_Die => S.S_Die :: stms
119 :     | AST.S_Stabilize => S.S_Stabilize :: stms
120 :     (* end case *))
121 :    
122 :     and simplifyExp (exp, stms) = (
123 :     case exp
124 :     of AST.E_Var x => (stms, S.E_Var x)
125 :     | AST.E_Lit lit => (stms, S.E_Lit lit)
126 :     | AST.E_Tuple es => raise Fail "E_Tuple not yet implemented"
127 :     | AST.E_Apply(f, tyArgs, args, ty) => let
128 :     val (stms, xs) = simplifyExpsToVars (args, stms)
129 :     in
130 :     (stms, S.E_Apply(f, tyArgs, xs, ty))
131 :     end
132 :     | AST.E_Cons es => let
133 :     val (stms, xs) = simplifyExpsToVars (es, stms)
134 :     in
135 :     (stms, S.E_Cons xs)
136 :     end
137 :     | AST.E_Cond(e1, e2, e3) => let
138 :     (* a conditional expression gets turned into an if-then-else statememt *)
139 :     val result = newTemp Ty.T_Bool
140 :     val (stms, x) = simplifyExpToVar (e1, stms)
141 :     fun simplifyBranch e = let
142 :     val (stms, e) = simplifyExp (e, [])
143 :     in
144 :     mkBlock (S.S_Assign(result, e)::stms)
145 :     end
146 :     val s1 = simplifyBranch e1
147 :     val s2 = simplifyBranch e2
148 :     in
149 :     (S.S_IfThenElse(x, s1, s2) :: stms, S.E_Var result)
150 :     end
151 :     (* end case *))
152 :    
153 :     and simplifyExpToVar (exp, stms) = let
154 :     val (stms, e) = simplifyExp (exp, stms)
155 :     in
156 :     case e
157 :     of S.E_Var x => (stms, x)
158 :     | _ => let
159 :     val x = newTemp (S.typeOf e)
160 :     in
161 :     (S.S_Assign(x, e)::stms, x)
162 :     end
163 :     (* end case *)
164 :     end
165 :    
166 :     and simplifyExpsToVars (exps, stms) = let
167 :     fun f ([], xs, stms) = (stms, List.rev xs)
168 :     | f (e::es, xs, stms) = let
169 :     val (stms, x) = simplifyExpToVar (e, stms)
170 :     in
171 :     f (es, x::xs, stms)
172 :     end
173 :     in
174 :     f (exps, [], stms)
175 :     end
176 :    
177 :     end

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