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cc540a7e SK |
1 | module List = ListLabels |
2 | ||
3 | module Temp = Tiger_temp | |
4 | ||
5 | type access = | |
6 | | InFrame of {offset_from_frame_pointer : int} | |
7 | | InReg of {register : Temp.Temp.t} | |
8 | ||
9 | type t = | |
10 | (* p.136 Frame.t is a data structure holding: | |
11 | * - the locations of all the formals | |
12 | * - instructions required to implement the "view shift" | |
13 | * - the number of locals allocated so far | |
14 | * - the `label` at which the function's machine code is to begin (see p.140) | |
15 | * *) | |
16 | { name : Temp.Label.t | |
17 | ; formals : access list | |
18 | ; locals_count : int | |
19 | ; instructions : unit (* TODO: instructions for view shift *) | |
20 | } | |
21 | ||
68e4b4a9 SK |
22 | let word_size_bits = 32 |
23 | let word_size_bytes = word_size_bits / 8 | |
24 | let word_size = word_size_bytes | |
25 | ||
cc540a7e SK |
26 | let name {name; _} = |
27 | name | |
28 | ||
29 | let formals {formals; _} = | |
30 | formals | |
31 | ||
32 | let alloc offset_from_frame_pointer ~escapes = | |
33 | if escapes then | |
34 | InFrame {offset_from_frame_pointer} | |
35 | else | |
36 | InReg {register = Temp.Temp.gen ()} | |
37 | ||
38 | let alloc_local _ ~escapes = | |
39 | (* FIXME: offset_from_frame_pointer. With neither mutation nor new frame? *) | |
40 | let offset_from_frame_pointer = 0 in | |
41 | alloc offset_from_frame_pointer ~escapes | |
42 | ||
43 | let make ~name ~formals = | |
44 | (* p.136: For each formal parameter, "newFrame" must calculate two things: | |
45 | * - How the parameter will be seen from inside the function | |
46 | * (in a register, or in a frame location); | |
47 | * - What instructions must be produced to implement the "view shift" | |
48 | * *) | |
49 | let formals, locals_count = | |
50 | (* TODO: What should offset increment be? Word? *) | |
51 | List.fold_left formals ~init:([], 0) ~f:(fun (formals, offset) escapes -> | |
52 | ((alloc offset ~escapes) :: formals, succ offset) | |
53 | ) | |
54 | in | |
55 | { name | |
56 | ; formals | |
57 | ; locals_count | |
58 | ; instructions = () (* TODO: instructions for view shift *) | |
59 | } |