rustc_codegen_ssa/
mono_item.rs

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
use rustc_hir as hir;
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::mir::mono::{Linkage, MonoItem, Visibility};
use rustc_middle::ty::Instance;
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
use rustc_middle::{span_bug, ty};
use tracing::debug;

use crate::traits::*;
use crate::{base, common};

pub trait MonoItemExt<'a, 'tcx> {
    fn define<Bx: BuilderMethods<'a, 'tcx>>(&self, cx: &'a Bx::CodegenCx);
    fn predefine<Bx: BuilderMethods<'a, 'tcx>>(
        &self,
        cx: &'a Bx::CodegenCx,
        linkage: Linkage,
        visibility: Visibility,
    );
    fn to_raw_string(&self) -> String;
}

impl<'a, 'tcx: 'a> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {
    fn define<Bx: BuilderMethods<'a, 'tcx>>(&self, cx: &'a Bx::CodegenCx) {
        debug!(
            "BEGIN IMPLEMENTING '{} ({})' in cgu {}",
            self,
            self.to_raw_string(),
            cx.codegen_unit().name()
        );

        match *self {
            MonoItem::Static(def_id) => {
                cx.codegen_static(def_id);
            }
            MonoItem::GlobalAsm(item_id) => {
                let item = cx.tcx().hir().item(item_id);
                if let hir::ItemKind::GlobalAsm(asm) = item.kind {
                    let operands: Vec<_> = asm
                        .operands
                        .iter()
                        .map(|(op, op_sp)| match *op {
                            hir::InlineAsmOperand::Const { ref anon_const } => {
                                match cx.tcx().const_eval_poly(anon_const.def_id.to_def_id()) {
                                    Ok(const_value) => {
                                        let ty = cx
                                            .tcx()
                                            .typeck_body(anon_const.body)
                                            .node_type(anon_const.hir_id);
                                        let string = common::asm_const_to_str(
                                            cx.tcx(),
                                            *op_sp,
                                            const_value,
                                            cx.layout_of(ty),
                                        );
                                        GlobalAsmOperandRef::Const { string }
                                    }
                                    Err(ErrorHandled::Reported { .. }) => {
                                        // An error has already been reported and
                                        // compilation is guaranteed to fail if execution
                                        // hits this path. So an empty string instead of
                                        // a stringified constant value will suffice.
                                        GlobalAsmOperandRef::Const { string: String::new() }
                                    }
                                    Err(ErrorHandled::TooGeneric(_)) => {
                                        span_bug!(
                                            *op_sp,
                                            "asm const cannot be resolved; too generic"
                                        )
                                    }
                                }
                            }
                            hir::InlineAsmOperand::SymFn { ref anon_const } => {
                                let ty = cx
                                    .tcx()
                                    .typeck_body(anon_const.body)
                                    .node_type(anon_const.hir_id);
                                let instance = match ty.kind() {
                                    &ty::FnDef(def_id, args) => Instance::new(def_id, args),
                                    _ => span_bug!(*op_sp, "asm sym is not a function"),
                                };

                                GlobalAsmOperandRef::SymFn { instance }
                            }
                            hir::InlineAsmOperand::SymStatic { path: _, def_id } => {
                                GlobalAsmOperandRef::SymStatic { def_id }
                            }
                            hir::InlineAsmOperand::In { .. }
                            | hir::InlineAsmOperand::Out { .. }
                            | hir::InlineAsmOperand::InOut { .. }
                            | hir::InlineAsmOperand::SplitInOut { .. }
                            | hir::InlineAsmOperand::Label { .. } => {
                                span_bug!(*op_sp, "invalid operand type for global_asm!")
                            }
                        })
                        .collect();

                    cx.codegen_global_asm(asm.template, &operands, asm.options, asm.line_spans);
                } else {
                    span_bug!(item.span, "Mismatch between hir::Item type and MonoItem type")
                }
            }
            MonoItem::Fn(instance) => {
                base::codegen_instance::<Bx>(cx, instance);
            }
        }

        debug!(
            "END IMPLEMENTING '{} ({})' in cgu {}",
            self,
            self.to_raw_string(),
            cx.codegen_unit().name()
        );
    }

    fn predefine<Bx: BuilderMethods<'a, 'tcx>>(
        &self,
        cx: &'a Bx::CodegenCx,
        linkage: Linkage,
        visibility: Visibility,
    ) {
        debug!(
            "BEGIN PREDEFINING '{} ({})' in cgu {}",
            self,
            self.to_raw_string(),
            cx.codegen_unit().name()
        );

        let symbol_name = self.symbol_name(cx.tcx()).name;

        debug!("symbol {symbol_name}");

        match *self {
            MonoItem::Static(def_id) => {
                cx.predefine_static(def_id, linkage, visibility, symbol_name);
            }
            MonoItem::Fn(instance) => {
                let attrs = cx.tcx().codegen_fn_attrs(instance.def_id());

                if attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
                    // do not define this function; it will become a global assembly block
                } else {
                    cx.predefine_fn(instance, linkage, visibility, symbol_name);
                };
            }
            MonoItem::GlobalAsm(..) => {}
        }

        debug!(
            "END PREDEFINING '{} ({})' in cgu {}",
            self,
            self.to_raw_string(),
            cx.codegen_unit().name()
        );
    }

    fn to_raw_string(&self) -> String {
        match *self {
            MonoItem::Fn(instance) => {
                format!("Fn({:?}, {})", instance.def, instance.args.as_ptr().addr())
            }
            MonoItem::Static(id) => format!("Static({id:?})"),
            MonoItem::GlobalAsm(id) => format!("GlobalAsm({id:?})"),
        }
    }
}