1 pub use crate::debug::transform::transform_dwarf;
2 use crate::debug::ModuleMemoryOffset;
3 use crate::CompiledFunctions;
4 use cranelift_codegen::ir::Endianness;
5 use cranelift_codegen::isa::{unwind::UnwindInfo, TargetIsa};
6 use cranelift_entity::EntityRef;
7 use gimli::write::{Address, Dwarf, EndianVec, FrameTable, Result, Sections, Writer};
8 use gimli::{RunTimeEndian, SectionId};
9 use wasmtime_environ::DebugInfoData;
10 
11 #[allow(missing_docs)]
12 pub struct DwarfSection {
13     pub name: &'static str,
14     pub body: Vec<u8>,
15     pub relocs: Vec<DwarfSectionReloc>,
16 }
17 
18 #[allow(missing_docs)]
19 #[derive(Clone)]
20 pub struct DwarfSectionReloc {
21     pub target: DwarfSectionRelocTarget,
22     pub offset: u32,
23     pub addend: i32,
24     pub size: u8,
25 }
26 
27 #[allow(missing_docs)]
28 #[derive(Clone)]
29 pub enum DwarfSectionRelocTarget {
30     Func(usize),
31     Section(&'static str),
32 }
33 
34 fn emit_dwarf_sections(
35     isa: &dyn TargetIsa,
36     mut dwarf: Dwarf,
37     frames: Option<FrameTable>,
38 ) -> anyhow::Result<Vec<DwarfSection>> {
39     let endian = match isa.endianness() {
40         Endianness::Little => RunTimeEndian::Little,
41         Endianness::Big => RunTimeEndian::Big,
42     };
43     let writer = WriterRelocate {
44         relocs: Vec::new(),
45         writer: EndianVec::new(endian),
46     };
47     let mut sections = Sections::new(writer);
48     dwarf.write(&mut sections)?;
49     if let Some(frames) = frames {
50         frames.write_debug_frame(&mut sections.debug_frame)?;
51     }
52 
53     let mut result = Vec::new();
54     sections.for_each_mut(|id, s| -> anyhow::Result<()> {
55         let name = id.name();
56         let body = s.writer.take();
57         let mut relocs = vec![];
58         ::std::mem::swap(&mut relocs, &mut s.relocs);
59         result.push(DwarfSection { name, body, relocs });
60         Ok(())
61     })?;
62 
63     Ok(result)
64 }
65 
66 #[derive(Clone)]
67 pub struct WriterRelocate {
68     relocs: Vec<DwarfSectionReloc>,
69     writer: EndianVec<RunTimeEndian>,
70 }
71 
72 impl Writer for WriterRelocate {
73     type Endian = RunTimeEndian;
74 
75     fn endian(&self) -> Self::Endian {
76         self.writer.endian()
77     }
78 
79     fn len(&self) -> usize {
80         self.writer.len()
81     }
82 
83     fn write(&mut self, bytes: &[u8]) -> Result<()> {
84         self.writer.write(bytes)
85     }
86 
87     fn write_at(&mut self, offset: usize, bytes: &[u8]) -> Result<()> {
88         self.writer.write_at(offset, bytes)
89     }
90 
91     fn write_address(&mut self, address: Address, size: u8) -> Result<()> {
92         match address {
93             Address::Constant(val) => self.write_udata(val, size),
94             Address::Symbol { symbol, addend } => {
95                 let offset = self.len() as u32;
96                 self.relocs.push(DwarfSectionReloc {
97                     target: DwarfSectionRelocTarget::Func(symbol),
98                     offset,
99                     size,
100                     addend: addend as i32,
101                 });
102                 self.write_udata(addend as u64, size)
103             }
104         }
105     }
106 
107     fn write_offset(&mut self, val: usize, section: SectionId, size: u8) -> Result<()> {
108         let offset = self.len() as u32;
109         let target = DwarfSectionRelocTarget::Section(section.name());
110         self.relocs.push(DwarfSectionReloc {
111             target,
112             offset,
113             size,
114             addend: val as i32,
115         });
116         self.write_udata(val as u64, size)
117     }
118 
119     fn write_offset_at(
120         &mut self,
121         offset: usize,
122         val: usize,
123         section: SectionId,
124         size: u8,
125     ) -> Result<()> {
126         let target = DwarfSectionRelocTarget::Section(section.name());
127         self.relocs.push(DwarfSectionReloc {
128             target,
129             offset: offset as u32,
130             size,
131             addend: val as i32,
132         });
133         self.write_udata_at(offset, val as u64, size)
134     }
135 }
136 
137 fn create_frame_table<'a>(isa: &dyn TargetIsa, funcs: &CompiledFunctions) -> Option<FrameTable> {
138     let mut table = FrameTable::default();
139 
140     let cie_id = table.add_cie(isa.create_systemv_cie()?);
141 
142     for (i, f) in funcs {
143         if let Some(UnwindInfo::SystemV(info)) = &f.unwind_info {
144             table.add_fde(
145                 cie_id,
146                 info.to_fde(Address::Symbol {
147                     symbol: i.index(),
148                     addend: 0,
149                 }),
150             );
151         }
152     }
153 
154     Some(table)
155 }
156 
157 pub fn emit_dwarf<'a>(
158     isa: &dyn TargetIsa,
159     debuginfo_data: &DebugInfoData,
160     funcs: &CompiledFunctions,
161     memory_offset: &ModuleMemoryOffset,
162 ) -> anyhow::Result<Vec<DwarfSection>> {
163     let dwarf = transform_dwarf(isa, debuginfo_data, funcs, memory_offset)?;
164     let frame_table = create_frame_table(isa, funcs);
165     let sections = emit_dwarf_sections(isa, dwarf, frame_table)?;
166     Ok(sections)
167 }
168