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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211

use super::IsPass;
use serde::{Deserialize, Serialize};
/// This pass will
/// - remove all store statements which is the only one store to a variable
/// - remove the load statements to the variable
/// - replace all usage of the load results to the source of the store
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, Deserialize, Serialize)]
pub struct RemoveOnlyOnceStore;

impl IsPass for RemoveOnlyOnceStore {
    fn need(&self) -> Vec<super::Pass> {
        Vec::new()
    }

    fn invalidate(&self) -> Vec<super::Pass> {
        Vec::new()
    }

    fn run(&self, editor: &mut crate::ir::editor::Editor) {
        let mut to_remove = Vec::new();
        let mut to_rename = Vec::new();
        for variable in editor
            .binded_analyzer()
            .memory_usage()
            .memory_access_variables()
        {
            let binded_analyzer = editor.binded_analyzer();
            let memory_usage = binded_analyzer.memory_usage();
            let memory_access_info = memory_usage.memory_access_info(variable);
            // todo: it is possible that the basic block the store statement in
            // cannot dominate the block a load is in, in such cases, an error should
            // be raised instead of do this optimize work
            if memory_access_info.store.len() == 1 {
                let store_statement_index = memory_access_info.store[0].clone();
                let store_statement = editor.content[store_statement_index.clone()].as_store();
                let stored_value = store_statement.source.clone();
                for load_statement_index in &memory_access_info.load {
                    let load_statement = editor.content[load_statement_index.clone()].as_load();
                    to_remove.push(load_statement_index.clone());
                    to_rename.push((load_statement.to.clone(), stored_value.clone()));
                }
                to_remove.push(store_statement_index.clone());
                to_remove.push(memory_access_info.alloca.clone().unwrap());
            }
        }
        editor.remove_statements(to_remove);
        for (from, to) in to_rename {
            editor.rename_local(from, to);
        }
    }
}

#[cfg(test)]
mod tests {
    #![allow(clippy::borrow_interior_mutable_const)]

    use std::collections::HashSet;

    use crate::{
        ir::{
            self,
            editor::Editor,
            function::basic_block::BasicBlock,
            optimize::pass::IsPass,
            statement::{
                calculate::binary::BinaryOperation, Alloca, BinaryCalculate, IsIRStatement, Jump,
                Load, Ret, Store,
            },
            FunctionDefinition, RegisterName,
        },
        utility::data_type::{self, Type},
    };

    use super::*;

    #[test]
    fn run() {
        let function = FunctionDefinition {
            header: ir::FunctionHeader {
                name: "f".to_string(),
                parameters: Vec::new(),
                return_type: Type::None,
            },
            content: vec![
                BasicBlock {
                    name: None,
                    content: vec![
                        Alloca {
                            to: RegisterName("0".to_string()),
                            alloc_type: data_type::I32.clone(),
                        }
                        .into(),
                        Store {
                            data_type: data_type::I32.clone(),
                            source: 42.into(),
                            target: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        Alloca {
                            to: RegisterName("1".to_string()),
                            alloc_type: data_type::I32.clone(),
                        }
                        .into(),
                        Store {
                            data_type: data_type::I32.clone(),
                            source: 42.into(),
                            target: RegisterName("1".to_string()).into(),
                        }
                        .into(),
                        Jump {
                            label: "bb1".to_string(),
                        }
                        .into(),
                    ],
                },
                BasicBlock {
                    name: Some("bb1".to_string()),
                    content: vec![
                        Load {
                            to: RegisterName("2".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("0".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("2".to_string()).into(),
                            operand2: RegisterName("2".to_string()).into(),
                            to: RegisterName("3".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Load {
                            to: RegisterName("4".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("1".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("4".to_string()).into(),
                            operand2: RegisterName("2".to_string()).into(),
                            to: RegisterName("5".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Jump {
                            label: "bb2".to_string(),
                        }
                        .into(),
                    ],
                },
                BasicBlock {
                    name: Some("bb2".to_string()),
                    content: vec![
                        Store {
                            data_type: data_type::I32.clone(),
                            source: 43.into(),
                            target: RegisterName("1".to_string()).into(),
                        }
                        .into(),
                        Load {
                            to: RegisterName("6".to_string()),
                            data_type: data_type::I32.clone(),
                            from: RegisterName("1".to_string()).into(),
                        }
                        .into(),
                        BinaryCalculate {
                            operation: BinaryOperation::Add,
                            operand1: RegisterName("6".to_string()).into(),
                            operand2: RegisterName("6".to_string()).into(),
                            to: RegisterName("7".to_string()),
                            data_type: data_type::I32.clone(),
                        }
                        .into(),
                        Jump {
                            label: "bb3".to_string(),
                        }
                        .into(),
                    ],
                },
                BasicBlock {
                    name: Some("bb3".to_string()),
                    content: vec![Ret {
                        value: Some(RegisterName("7".to_string()).into()),
                    }
                    .into()],
                },
            ],
        };
        let mut editor = Editor::new(function);
        let pass = RemoveOnlyOnceStore;
        pass.run(&mut editor);
        // %0 and %2 should be optimized out
        let mut registers = HashSet::new();
        for statement in editor.content.iter() {
            if let Some((r, _)) = statement.generate_register() {
                registers.insert(r);
            }
            registers.extend(statement.use_register());
        }
        assert!(!registers.contains(&RegisterName("0".to_string())));
        assert!(registers.contains(&RegisterName("1".to_string())));
        assert!(!registers.contains(&RegisterName("2".to_string())));
        assert!(registers.contains(&RegisterName("3".to_string())));
        assert!(registers.contains(&RegisterName("4".to_string())));
        assert!(registers.contains(&RegisterName("5".to_string())));
        assert!(registers.contains(&RegisterName("6".to_string())));
        assert!(registers.contains(&RegisterName("7".to_string())));
    }
}