aboutsummaryrefslogtreecommitdiffstats
path: root/src/hls/IfConversion.v
blob: 1825ee713b6d2eddc381f53efcf0b4df9e1961b6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
(*
 * Vericert: Verified high-level synthesis.
 * Copyright (C) 2021 Yann Herklotz <yann@yannherklotz.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *)

Require Import compcert.common.AST.
Require Import compcert.common.Errors.
Require Import compcert.common.Globalenvs.
Require Import compcert.lib.Integers.
Require Import compcert.lib.Maps.

Require Import vericert.common.Vericertlib.
Require Import vericert.hls.Gible.
Require Import vericert.hls.GibleSeq.
Require Import vericert.hls.Predicate.
Require Import vericert.bourdoncle.Bourdoncle.

Parameter build_bourdoncle : function -> (bourdoncle * PMap.t N).

(*|
=============
If-Conversion
=============

This conversion is a verified conversion from RTLBlock back to itself, which
performs if-conversion on basic blocks to make basic blocks larger.
|*)

Definition combine_pred (p: pred_op) (optp: option pred_op) :=
  match optp with
  | Some p' => Pand p p'
  | None => p
  end.

Definition map_if_convert (p: pred_op) (i: instr) :=
  match i with
  | RBop p' op args dst => RBop (Some (combine_pred p p')) op args dst
  | RBload p' chunk addr args dst =>
    RBload (Some (combine_pred p p')) chunk addr args dst
  | RBstore p' chunk addr args src =>
    RBstore (Some (combine_pred p p')) chunk addr args src
  | RBsetpred p' c l pred =>
      RBsetpred (Some (combine_pred p p')) c l pred
  | RBexit p' cf => RBexit (Some (combine_pred p p')) cf
  | _ => i
  end.

Definition get_unconditional_exit (bb: SeqBB.t) := List.nth_error bb (length bb - 1).

Definition if_convert_block (c: code) (p: predicate) (bb: SeqBB.t) : SeqBB.t :=
  match get_unconditional_exit bb with
  | Some (RBexit None (RBcond cond args n1 n2)) =>
    match PTree.get n1 c, PTree.get n2 c with
    | Some bb1, Some bb2 =>
      let bb1' := List.map (map_if_convert (Plit (true, p))) bb1 in
      let bb2' := List.map (map_if_convert (Plit (false, p))) bb2 in
      List.concat (bb :: ((RBsetpred None cond args p) :: bb1') :: bb2' :: nil)
    | _, _ => bb
    end
  | _ => bb
  end.

Definition is_cond_cfi' (cfi: cf_instr) :=
  match cfi with
  | RBcond _ _ _ _ => true
  | _ => false
  end.

Definition is_cond_cfi (b: SeqBB.t) :=
  match get_unconditional_exit b with
  | Some (RBexit None (RBcond _ _ _ _)) => true
  | _ => false
  end.

Fixpoint any {A: Type} (f: A -> bool) (a: list A) :=
  match a with
  | x :: xs => f x || any f xs
  | nil => false
  end.

Fixpoint all {A: Type} (f: A -> bool) (a: list A) :=
  match a with
  | x :: xs => f x && all f xs
  | nil => true
  end.

Definition find_backedge (nb: node * SeqBB.t) :=
  let (n, b) := nb in
  let succs := all_successors b in
  filter (fun x => Pos.ltb n x) succs.

Definition find_all_backedges (c: code) : list node :=
  List.concat (List.map find_backedge (PTree.elements c)).

Definition has_backedge (entry: node) (be: list node) :=
  any (fun x => Pos.eqb entry x) be.

Fixpoint get_loops (b: bourdoncle): list node :=
  match b with
  | L h b' => h::(fold_right (fun a b => get_loops a ++ b) nil b')
  | I h => nil
  end.

Definition is_loop (b: list node) (n: node) :=
  any (Pos.eqb n) b.

Definition is_flat_cfi' (n: cf_instr) :=
  match n with
  | RBcond _ _ _ _ => false
  | RBjumptable _ _ => false
  | _ => true
  end.

Definition is_flat_cfi (n: SeqBB.t) :=
  (length (all_successors n) =? 1)%nat.

Definition is_flat (c: code) (succ: node) :=
  match c ! succ with
  | Some bblock => is_flat_cfi bblock
  | None => false
  end.

Definition find_blocks_with_cond ep (b: list node) (c: code) : list (node * SeqBB.t) :=
  let backedges := find_all_backedges c in
  List.filter (fun x => is_cond_cfi (snd x) &&
                        (negb (is_loop b (fst x)) || Pos.eqb (fst x) ep) &&
                        all (fun x' => is_flat c x')
                            (all_successors (snd x))
              ) (PTree.elements c).

Definition if_convert_code (p: nat * code) (nb: node * SeqBB.t) :=
  let nbb := if_convert_block (snd p) (Pos.of_nat (fst p)) (snd nb) in
  (S (fst p), PTree.set (fst nb) nbb (snd p)).

Definition transf_function (f: function) : function :=
  let (b, _) := build_bourdoncle f in
  let b' := get_loops b in
  let (_, c) := List.fold_left if_convert_code
                               (find_blocks_with_cond f.(fn_entrypoint) b' f.(fn_code))
                               (1%nat, f.(fn_code)) in
  mkfunction f.(fn_sig) f.(fn_params) f.(fn_stacksize) c f.(fn_entrypoint).

Definition transf_fundef (fd: fundef) : fundef :=
  transf_fundef transf_function fd.

Definition transf_program (p: program) : program :=
  transform_program transf_fundef p.