calyx_opt/passes/
dead_group_removal.rs

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
161
162
163
164
165
166
167
168
use crate::traversal::{Action, Named, VisResult, Visitor};
use calyx_ir::{self as ir, LibrarySignatures};
use std::collections::HashSet;

/// Removes unused groups and combinational groups from components.
/// A group is considered in use when it shows up in an [ir::Enable].
/// A combinational group is considered in use when it is a part of an
/// [ir::If] or [ir::While] or [ir::Invoke].
#[derive(Default)]
pub struct DeadGroupRemoval {
    used_groups: HashSet<ir::Id>,
    used_comb_groups: HashSet<ir::Id>,
}

impl DeadGroupRemoval {
    /// A function that in-place updates a Vec with the name of the parent
    /// of a port, if that port parent is a Group
    fn push_group_names(
        group_names: &mut Vec<ir::Id>,
        port: &ir::RRC<ir::Port>,
    ) {
        if let ir::PortParent::Group(group_wref) = &port.borrow().parent {
            group_names.push(group_wref.upgrade().borrow().name());
        }
    }
}

impl Named for DeadGroupRemoval {
    fn name() -> &'static str {
        "dead-group-removal"
    }

    fn description() -> &'static str {
        "removes unsed groups from components"
    }
}

impl Visitor for DeadGroupRemoval {
    fn enable(
        &mut self,
        s: &mut ir::Enable,
        _comp: &mut ir::Component,
        _sigs: &ir::LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        self.used_groups.insert(s.group.borrow().name());
        Ok(Action::Continue)
    }

    fn fsm_enable(
        &mut self,
        s: &mut calyx_ir::FSMEnable,
        _comp: &mut calyx_ir::Component,
        _sigs: &LibrarySignatures,
        _comps: &[calyx_ir::Component],
    ) -> VisResult {
        // add all groups that are assigned to / read from, by the parent FSM
        self.used_groups.extend(
            s.fsm
                .borrow()
                .get_called_port_parents(DeadGroupRemoval::push_group_names),
        );
        Ok(Action::Continue)
    }

    fn static_enable(
        &mut self,
        s: &mut ir::StaticEnable,
        _comp: &mut ir::Component,
        _sigs: &ir::LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        self.used_groups.insert(s.group.borrow().name());
        Ok(Action::Continue)
    }

    fn finish_if(
        &mut self,
        s: &mut ir::If,
        _comp: &mut ir::Component,
        _sigs: &ir::LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        if let Some(cg) = &s.cond {
            self.used_comb_groups.insert(cg.borrow().name());
        }
        Ok(Action::Continue)
    }

    fn invoke(
        &mut self,
        s: &mut ir::Invoke,
        _comp: &mut ir::Component,
        _sigs: &ir::LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        if let Some(cg) = &s.comb_group {
            self.used_comb_groups.insert(cg.borrow().name());
        }
        Ok(Action::Continue)
    }

    fn finish_while(
        &mut self,
        s: &mut ir::While,
        _comp: &mut ir::Component,
        _sigs: &ir::LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        if let Some(cg) = &s.cond {
            self.used_comb_groups.insert(cg.borrow().name());
        }
        Ok(Action::Continue)
    }

    fn finish(
        &mut self,
        comp: &mut ir::Component,
        _sigs: &LibrarySignatures,
        _comps: &[ir::Component],
    ) -> VisResult {
        // Groups that are driven by their `go` signals should not be
        // removed.
        for group in comp.get_groups().iter() {
            for assign in &group.borrow().assignments {
                let dst = assign.dst.borrow();
                if dst.is_hole() && dst.name == "go" {
                    self.used_groups.insert(dst.get_parent_name());
                }
            }
        }

        for assign in &comp.continuous_assignments {
            let dst = assign.dst.borrow();
            if dst.is_hole() && dst.name == "go" {
                self.used_groups.insert(dst.get_parent_name());
            }
        }

        for group in comp.get_static_groups().iter() {
            for assign in &group.borrow().assignments {
                let dst = assign.dst.borrow();
                if dst.is_hole() && dst.name == "go" {
                    self.used_groups.insert(dst.get_parent_name());
                }
            }
        }

        // add all groups invoked by each fsm
        for fsm in comp.get_fsms().iter() {
            self.used_groups.extend(
                fsm.borrow().get_called_port_parents(
                    DeadGroupRemoval::push_group_names,
                ),
            );
        }

        // Remove Groups that are not used
        comp.get_groups_mut()
            .retain(|g| self.used_groups.contains(&g.borrow().name()));
        comp.get_static_groups_mut()
            .retain(|g| self.used_groups.contains(&g.borrow().name()));
        comp.comb_groups
            .retain(|cg| self.used_comb_groups.contains(&cg.borrow().name()));

        Ok(Action::Stop)
    }
}