beamr 0.4.6

A Rust runtime with the BEAM's execution model, targeting Gleam
Documentation 
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

//! Map runtime helpers callable from JIT-generated code.

use crate::gc;
use crate::process::Process;
use crate::term::Term;
use crate::term::boxed::{Map, write_map};
use crate::term::compare;

use super::ir_exceptions::JitReturn;
use super::runtime::process_from_abi;

pub(crate) extern "C" fn jit_map_new(
    process: *mut Process,
    source: u64,
    pairs: *const u64,
    pair_count: u64,
) -> u64 {
    let Some(process) = process_from_abi(process) else {
        return 0;
    };
    map_update(process, Term::from_raw(source), pairs, pair_count, false)
}

pub(crate) extern "C" fn jit_map_update(
    process: *mut Process,
    source: u64,
    pairs: *const u64,
    pair_count: u64,
) -> u64 {
    let Some(process) = process_from_abi(process) else {
        return 0;
    };
    map_update(process, Term::from_raw(source), pairs, pair_count, true)
}

pub(crate) extern "C" fn jit_map_get(map: u64, key: u64) -> JitReturn {
    let Some(map) = Map::new(Term::from_raw(map)) else {
        return map_get_return(0, 0);
    };
    map.get(Term::from_raw(key)).map_or_else(
        || map_get_return(0, 0),
        |value| map_get_return(1, value.raw()),
    )
}

pub(crate) extern "C" fn jit_map_has_key(map: u64, key: u64) -> u8 {
    Map::new(Term::from_raw(map))
        .and_then(|map| map.get(Term::from_raw(key)))
        .map_or(0, |_| 1)
}

fn map_update(
    process: &mut Process,
    source: Term,
    pairs: *const u64,
    pair_count: u64,
    exact: bool,
) -> u64 {
    let Some(source_map) = Map::new(source) else {
        return 0;
    };
    let Some(updates) = map_pair_terms(pairs, pair_count) else {
        return 0;
    };
    let Some(mut entries) = map_entries(source_map) else {
        return 0;
    };
    if exact
        && updates.iter().any(|(key, _value)| {
            entries
                .iter()
                .all(|(existing_key, _value)| *existing_key != *key)
        })
    {
        return 0;
    }
    for (key, value) in updates {
        if let Some((_existing_key, existing_value)) = entries
            .iter_mut()
            .find(|(existing_key, _value)| *existing_key == key)
        {
            *existing_value = value;
        } else {
            entries.push((key, value));
        }
    }
    entries.sort_by(|(left, _), (right, _)| compare::raw_cmp(*left, *right));
    write_map_entries(process, &entries).map_or(0, Term::raw)
}

fn map_pair_terms(pairs: *const u64, pair_count: u64) -> Option<Vec<(Term, Term)>> {
    let pair_count = usize::try_from(pair_count).ok()?;
    let term_count = pair_count.checked_mul(2)?;
    if term_count > 0 && pairs.is_null() {
        return None;
    }
    let raw_pairs = if term_count == 0 {
        &[]
    } else {
        // SAFETY: Generated code passes a stack slot containing exactly
        // `pair_count * 2` raw term words for the duration of this helper call.
        unsafe { std::slice::from_raw_parts(pairs, term_count) }
    };
    Some(
        raw_pairs
            .chunks_exact(2)
            .map(|pair| (Term::from_raw(pair[0]), Term::from_raw(pair[1])))
            .collect(),
    )
}

const fn map_get_return(status: u8, value: u64) -> JitReturn {
    JitReturn {
        status,
        _padding: [0; 7],
        value,
    }
}

fn map_entries(map: Map) -> Option<Vec<(Term, Term)>> {
    let mut entries = Vec::with_capacity(map.len());
    for index in 0..map.len() {
        entries.push((map.key(index)?, map.value(index)?));
    }
    Some(entries)
}

fn write_map_entries(process: &mut Process, entries: &[(Term, Term)]) -> Option<Term> {
    let words = map_word_count(entries.len())?;
    let keys = entries.iter().map(|(key, _value)| *key).collect::<Vec<_>>();
    let values = entries
        .iter()
        .map(|(_key, value)| *value)
        .collect::<Vec<_>>();
    if gc::ensure_space(process, words, 256).is_err() {
        return None;
    }
    let heap = process.heap_mut().alloc_slice(words).ok()?;
    write_map(heap, &keys, &values)
}

fn map_word_count(entries: usize) -> Option<usize> {
    entries.checked_mul(2)?.checked_add(2)
}