wasmi 0.38.0

WebAssembly interpreter
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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162

use super::{Executor, InstructionPtr};
use crate::{
    core::UntypedVal,
    engine::{
        bytecode::{AnyConst32, Const32, Instruction, Reg},
        utils::unreachable_unchecked,
    },
};

impl<'engine> Executor<'engine> {
    /// Fetches two [`Reg`]s.
    fn fetch_register_2(&self) -> (Reg, Reg) {
        let mut addr: InstructionPtr = self.ip;
        addr.add(1);
        match *addr.get() {
            Instruction::Register2 { regs: [reg0, reg1] } => (reg0, reg1),
            unexpected => {
                // Safety: Wasmi translation guarantees that [`Instruction::Register2`] exists.
                unsafe {
                    unreachable_unchecked!(
                        "expected `Instruction::Register2` but found {unexpected:?}"
                    )
                }
            }
        }
    }

    /// Fetches a [`Reg`] and a 32-bit immediate value of type `T`.
    fn fetch_register_and_imm32<T>(&self) -> (Reg, T)
    where
        T: From<AnyConst32>,
    {
        let mut addr: InstructionPtr = self.ip;
        addr.add(1);
        match *addr.get() {
            Instruction::RegisterAndImm32 { reg, imm } => (reg, T::from(imm)),
            unexpected => {
                // Safety: Wasmi translation guarantees that [`Instruction::RegisterAndImm32`] exists.
                unsafe {
                    unreachable_unchecked!(
                        "expected `Instruction::RegisterAndImm32` but found {unexpected:?}"
                    )
                }
            }
        }
    }

    /// Executes a `select` instruction generically.
    fn execute_select_impl<L, R>(
        &mut self,
        result: Reg,
        condition: Reg,
        lhs: impl FnOnce(&Self) -> L,
        rhs: impl FnOnce(&Self) -> R,
    ) where
        L: Into<UntypedVal>,
        R: Into<UntypedVal>,
    {
        let condition: bool = self.get_register_as(condition);
        let selected = match condition {
            true => lhs(self).into(),
            false => rhs(self).into(),
        };
        self.set_register(result, selected);
        self.next_instr_at(2);
    }

    /// Executes an [`Instruction::Select`].
    pub fn execute_select(&mut self, result: Reg, lhs: Reg) {
        let (condition, rhs) = self.fetch_register_2();
        self.execute_select_impl(
            result,
            condition,
            |this| this.get_register(lhs),
            |this| this.get_register(rhs),
        )
    }

    /// Executes an [`Instruction::SelectImm32Rhs`].
    pub fn execute_select_imm32_rhs(&mut self, result: Reg, lhs: Reg) {
        let (condition, rhs) = self.fetch_register_and_imm32::<AnyConst32>();
        self.execute_select_impl(
            result,
            condition,
            |this: &Executor<'engine>| this.get_register(lhs),
            |_| u32::from(rhs),
        )
    }

    /// Executes an [`Instruction::SelectImm32Lhs`].
    pub fn execute_select_imm32_lhs(&mut self, result: Reg, lhs: AnyConst32) {
        let (condition, rhs) = self.fetch_register_2();
        self.execute_select_impl(
            result,
            condition,
            |_| u32::from(lhs),
            |this| this.get_register(rhs),
        )
    }

    /// Executes an [`Instruction::SelectImm32`].
    pub fn execute_select_imm32(&mut self, result: Reg, lhs: AnyConst32) {
        let (condition, rhs) = self.fetch_register_and_imm32::<AnyConst32>();
        self.execute_select_impl(result, condition, |_| u32::from(lhs), |_| u32::from(rhs))
    }

    /// Executes an [`Instruction::SelectI64Imm32Rhs`].
    pub fn execute_select_i64imm32_rhs(&mut self, result: Reg, lhs: Reg) {
        let (condition, rhs) = self.fetch_register_and_imm32::<i32>();
        self.execute_select_impl(
            result,
            condition,
            |this| this.get_register(lhs),
            |_| i64::from(rhs),
        )
    }

    /// Executes an [`Instruction::SelectI64Imm32Lhs`].
    pub fn execute_select_i64imm32_lhs(&mut self, result: Reg, lhs: Const32<i64>) {
        let (condition, rhs) = self.fetch_register_2();
        self.execute_select_impl(
            result,
            condition,
            |_| i64::from(lhs),
            |this| this.get_register(rhs),
        )
    }

    /// Executes an [`Instruction::SelectI64Imm32`].
    pub fn execute_select_i64imm32(&mut self, result: Reg, lhs: Const32<i64>) {
        let (condition, rhs) = self.fetch_register_and_imm32::<i32>();
        self.execute_select_impl(result, condition, |_| i64::from(lhs), |_| i64::from(rhs))
    }

    /// Executes an [`Instruction::SelectF64Imm32Rhs`].
    pub fn execute_select_f64imm32_rhs(&mut self, result: Reg, lhs: Reg) {
        let (condition, rhs) = self.fetch_register_and_imm32::<f32>();
        self.execute_select_impl(
            result,
            condition,
            |this| this.get_register(lhs),
            |_| f64::from(rhs),
        )
    }

    /// Executes an [`Instruction::SelectF64Imm32Lhs`].
    pub fn execute_select_f64imm32_lhs(&mut self, result: Reg, lhs: Const32<f64>) {
        let (condition, rhs) = self.fetch_register_2();
        self.execute_select_impl(
            result,
            condition,
            |_| f64::from(lhs),
            |this| this.get_register(rhs),
        )
    }

    /// Executes an [`Instruction::SelectF64Imm32`].
    pub fn execute_select_f64imm32(&mut self, result: Reg, lhs: Const32<f64>) {
        let (condition, rhs) = self.fetch_register_and_imm32::<f32>();
        self.execute_select_impl(result, condition, |_| f64::from(lhs), |_| f64::from(rhs))
    }
}