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
pub use Integer::*;
pub use Primitive::*;

use crate::json::{Json, ToJson};

use std::fmt;
use std::ops::Deref;

use rustc_macros::HashStable_Generic;

pub mod call;

pub use rustc_abi::*;

impl ToJson for Endian {
    fn to_json(&self) -> Json {
        self.as_str().to_json()
    }
}

/// The layout of a type, alongside the type itself.
/// Provides various type traversal APIs (e.g., recursing into fields).
///
/// Note that the layout is NOT guaranteed to always be identical
/// to that obtained from `layout_of(ty)`, as we need to produce
/// layouts for which Rust types do not exist, such as enum variants
/// or synthetic fields of enums (i.e., discriminants) and fat pointers.
#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable_Generic)]
pub struct TyAndLayout<'a, Ty> {
    pub ty: Ty,
    pub layout: Layout<'a>,
}

impl<'a, Ty: fmt::Display> fmt::Debug for TyAndLayout<'a, Ty> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        // Print the type in a readable way, not its debug representation.
        f.debug_struct("TyAndLayout")
            .field("ty", &format_args!("{}", self.ty))
            .field("layout", &self.layout)
            .finish()
    }
}

impl<'a, Ty> Deref for TyAndLayout<'a, Ty> {
    type Target = &'a LayoutS;
    fn deref(&self) -> &&'a LayoutS {
        &self.layout.0.0
    }
}

/// Trait that needs to be implemented by the higher-level type representation
/// (e.g. `rustc_middle::ty::Ty`), to provide `rustc_target::abi` functionality.
pub trait TyAbiInterface<'a, C>: Sized + std::fmt::Debug {
    fn ty_and_layout_for_variant(
        this: TyAndLayout<'a, Self>,
        cx: &C,
        variant_index: VariantIdx,
    ) -> TyAndLayout<'a, Self>;
    fn ty_and_layout_field(this: TyAndLayout<'a, Self>, cx: &C, i: usize) -> TyAndLayout<'a, Self>;
    fn ty_and_layout_pointee_info_at(
        this: TyAndLayout<'a, Self>,
        cx: &C,
        offset: Size,
    ) -> Option<PointeeInfo>;
    fn is_adt(this: TyAndLayout<'a, Self>) -> bool;
    fn is_never(this: TyAndLayout<'a, Self>) -> bool;
    fn is_tuple(this: TyAndLayout<'a, Self>) -> bool;
    fn is_unit(this: TyAndLayout<'a, Self>) -> bool;
    fn is_transparent(this: TyAndLayout<'a, Self>) -> bool;
}

impl<'a, Ty> TyAndLayout<'a, Ty> {
    pub fn for_variant<C>(self, cx: &C, variant_index: VariantIdx) -> Self
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::ty_and_layout_for_variant(self, cx, variant_index)
    }

    pub fn field<C>(self, cx: &C, i: usize) -> Self
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::ty_and_layout_field(self, cx, i)
    }

    pub fn pointee_info_at<C>(self, cx: &C, offset: Size) -> Option<PointeeInfo>
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::ty_and_layout_pointee_info_at(self, cx, offset)
    }

    pub fn is_single_fp_element<C>(self, cx: &C) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
        C: HasDataLayout,
    {
        match self.abi {
            Abi::Scalar(scalar) => matches!(scalar.primitive(), F32 | F64),
            Abi::Aggregate { .. } => {
                if self.fields.count() == 1 && self.fields.offset(0).bytes() == 0 {
                    self.field(cx, 0).is_single_fp_element(cx)
                } else {
                    false
                }
            }
            _ => false,
        }
    }

    pub fn is_adt<C>(self) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::is_adt(self)
    }

    pub fn is_never<C>(self) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::is_never(self)
    }

    pub fn is_tuple<C>(self) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::is_tuple(self)
    }

    pub fn is_unit<C>(self) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::is_unit(self)
    }

    pub fn is_transparent<C>(self) -> bool
    where
        Ty: TyAbiInterface<'a, C>,
    {
        Ty::is_transparent(self)
    }

    pub fn offset_of_subfield<C>(self, cx: &C, indices: impl Iterator<Item = usize>) -> Size
    where
        Ty: TyAbiInterface<'a, C>,
    {
        let mut layout = self;
        let mut offset = Size::ZERO;

        for index in indices {
            offset += layout.fields.offset(index);
            layout = layout.field(cx, index);
            assert!(
                layout.is_sized(),
                "offset of unsized field (type {:?}) cannot be computed statically",
                layout.ty
            );
        }

        offset
    }

    /// Finds the one field that is not a 1-ZST.
    /// Returns `None` if there are multiple non-1-ZST fields or only 1-ZST-fields.
    pub fn non_1zst_field<C>(&self, cx: &C) -> Option<(usize, Self)>
    where
        Ty: TyAbiInterface<'a, C> + Copy,
    {
        let mut found = None;
        for field_idx in 0..self.fields.count() {
            let field = self.field(cx, field_idx);
            if field.is_1zst() {
                continue;
            }
            if found.is_some() {
                // More than one non-1-ZST field.
                return None;
            }
            found = Some((field_idx, field));
        }
        found
    }
}