padlock_source/
concurrency.rs

1// padlock-source/src/concurrency.rs
2//
3// Heuristic pass: annotate field AccessPatterns based on known concurrency
4// type names in Rust, C++, and Go.
5
6use padlock_core::ir::{AccessPattern, StructLayout};
7
8use crate::SourceLanguage;
9
10/// Update `AccessPattern` for fields whose type names suggest concurrent access.
11///
12/// This is a best-effort heuristic: it matches well-known synchronisation
13/// wrapper names (`Mutex<T>`, `std::atomic<T>`, `sync.Mutex`, etc.) found in
14/// the `TypeInfo` name of each field.
15pub fn annotate_concurrency(layout: &mut StructLayout, language: &SourceLanguage) {
16    for field in &mut layout.fields {
17        let ty_name = match &field.ty {
18            padlock_core::ir::TypeInfo::Primitive { name, .. }
19            | padlock_core::ir::TypeInfo::Opaque { name, .. } => name.clone(),
20            _ => continue,
21        };
22
23        if is_concurrent_type(&ty_name, language) {
24            let is_atomic = is_atomic_type(&ty_name, language);
25            if matches!(field.access, AccessPattern::Unknown) {
26                // Use the field name as the guard so that two concurrent fields
27                // with different names on the same cache line are flagged as
28                // false-sharing candidates (different guards → different data).
29                field.access = AccessPattern::Concurrent {
30                    guard: Some(field.name.clone()),
31                    is_atomic,
32                };
33            }
34        } else if is_read_mostly_type(&ty_name, language)
35            && matches!(field.access, AccessPattern::Unknown)
36        {
37            field.access = AccessPattern::ReadMostly;
38        }
39    }
40}
41
42/// Returns `true` if any field has a `Concurrent` access pattern.
43pub fn has_concurrent_fields(layout: &StructLayout) -> bool {
44    layout
45        .fields
46        .iter()
47        .any(|f| matches!(f.access, AccessPattern::Concurrent { .. }))
48}
49
50fn is_concurrent_type(name: &str, lang: &SourceLanguage) -> bool {
51    match lang {
52        SourceLanguage::Rust => {
53            name.starts_with("Mutex")
54                || name.starts_with("RwLock")
55                || name.starts_with("Arc")
56                || name.contains("Atomic")
57                || name.starts_with("Condvar")
58                || name.starts_with("Once")
59        }
60        SourceLanguage::C | SourceLanguage::Cpp => {
61            name.contains("mutex")
62                || name.contains("atomic")
63                || name.contains("spinlock")
64                || name.contains("critical_section")
65                || name.contains("pthread_mutex")
66        }
67        SourceLanguage::Go => {
68            name == "sync.Mutex"
69                || name == "sync.RWMutex"
70                || name == "Mutex"
71                || name == "RWMutex"
72                || name.contains("atomic")
73        }
74        SourceLanguage::Zig => {
75            name.contains("Mutex")
76                || name.contains("RwLock")
77                || name.contains("atomic.Value")
78                || name.contains("Atomic")
79        }
80    }
81}
82
83fn is_atomic_type(name: &str, lang: &SourceLanguage) -> bool {
84    match lang {
85        SourceLanguage::Rust => name.contains("Atomic"),
86        SourceLanguage::C | SourceLanguage::Cpp => name.contains("atomic"),
87        SourceLanguage::Go => name.contains("atomic"),
88        SourceLanguage::Zig => name.contains("atomic.Value") || name.contains("Atomic"),
89    }
90}
91
92fn is_read_mostly_type(name: &str, lang: &SourceLanguage) -> bool {
93    match lang {
94        SourceLanguage::Rust => name.starts_with("RwLock"),
95        SourceLanguage::C | SourceLanguage::Cpp => {
96            name.contains("rwlock") || name.contains("shared_mutex")
97        }
98        SourceLanguage::Go => name == "sync.RWMutex" || name == "RWMutex",
99        SourceLanguage::Zig => name.contains("RwLock"),
100    }
101}
102
103// ── tests ─────────────────────────────────────────────────────────────────────
104
105#[cfg(test)]
106mod tests {
107    use super::*;
108    use padlock_core::arch::X86_64_SYSV;
109    use padlock_core::ir::{AccessPattern, Field, StructLayout, TypeInfo};
110
111    fn field_with_type(name: &str, ty_name: &str) -> Field {
112        Field {
113            name: name.into(),
114            ty: TypeInfo::Primitive {
115                name: ty_name.into(),
116                size: 8,
117                align: 8,
118            },
119            offset: 0,
120            size: 8,
121            align: 8,
122            source_file: None,
123            source_line: None,
124            access: AccessPattern::Unknown,
125        }
126    }
127
128    fn layout_with_fields(fields: Vec<Field>) -> StructLayout {
129        StructLayout {
130            name: "T".into(),
131            total_size: 64,
132            align: 8,
133            fields,
134            source_file: None,
135            source_line: None,
136            arch: &X86_64_SYSV,
137            is_packed: false,
138            is_union: false,
139            is_repr_rust: false,
140        }
141    }
142
143    #[test]
144    fn rust_mutex_field_is_annotated() {
145        let mut layout = layout_with_fields(vec![field_with_type("counter", "Mutex")]);
146        annotate_concurrency(&mut layout, &SourceLanguage::Rust);
147        assert!(matches!(
148            layout.fields[0].access,
149            AccessPattern::Concurrent { .. }
150        ));
151    }
152
153    #[test]
154    fn rust_atomic_is_atomic() {
155        let mut layout = layout_with_fields(vec![field_with_type("count", "AtomicU64")]);
156        annotate_concurrency(&mut layout, &SourceLanguage::Rust);
157        if let AccessPattern::Concurrent { is_atomic, .. } = &layout.fields[0].access {
158            assert!(is_atomic);
159        } else {
160            panic!("expected Concurrent");
161        }
162    }
163
164    #[test]
165    fn cpp_mutex_annotated() {
166        let mut layout = layout_with_fields(vec![field_with_type("mu", "std::mutex")]);
167        annotate_concurrency(&mut layout, &SourceLanguage::Cpp);
168        assert!(has_concurrent_fields(&layout));
169    }
170
171    #[test]
172    fn unknown_field_stays_unknown() {
173        let mut layout = layout_with_fields(vec![field_with_type("x", "int")]);
174        annotate_concurrency(&mut layout, &SourceLanguage::C);
175        assert!(matches!(layout.fields[0].access, AccessPattern::Unknown));
176    }
177
178    #[test]
179    fn has_concurrent_fields_false_when_none() {
180        let layout = layout_with_fields(vec![field_with_type("x", "int")]);
181        assert!(!has_concurrent_fields(&layout));
182    }
183}
padlock_source/concurrency.rs

padlock_source/
concurrency.rs
