Method finish

cranelift/object/src/unwind.rs:89–134

Serialize all collected FDEs into an `.eh_frame` section on `object`. Returns without writing anything if no FDE was ever added (e.g. when the user enabled unwind info on a target that does not produce System V frames). The pointer-width unwrap is safe because [`ObjectBuilder`] has already rejected unknown architectures during construction. [`ObjectBuilder`]: crate::ObjectBuilder

(self, object: &mut Object<'static>, isa: &dyn TargetIsa)

    ///
    /// [`ObjectBuilder`]: crate::ObjectBuilder
    pub(crate) fn finish(self, object: &mut Object<'static>, isa: &dyn TargetIsa) -> Result<()> {
        let UnwindBuilder {
            section,
            frame_table,
            cie_id,
            symbols,
        } = self;
        if cie_id.is_none() {
            return Ok(());
        }
        let mut eh_frame = EhFrame(section);
        frame_table
            .write_eh_frame(&mut eh_frame)
            .map_err(|err| anyhow!("failed to write .eh_frame: {err}"))?;
        let EhFrame(EhFrameSection {
            writer,
            relocations,
        }) = eh_frame;

        let section_id = object.section_id(StandardSection::EhFrame);
        let alignment = u64::from(isa.triple().pointer_width().unwrap().bytes());
        object.append_section_data(section_id, &writer.into_vec(), alignment);

        let format = object.format();
        for reloc in relocations {
            let symbol_id = match reloc.target {
                RelocationTarget::Symbol(index) => symbols[index],
                // gimli's writer only emits section-relative relocations for
                // DWARF debug sections, never for `.eh_frame`. Skip defensively.
                RelocationTarget::Section(_) => continue,
            };
            let flags = translate_eh_pe(reloc.eh_pe, reloc.size, format)?;
            object
                .add_relocation(
                    section_id,
                    ObjectRelocation {
                        offset: reloc.offset as u64,
                        symbol: symbol_id,
                        addend: reloc.addend,
                        flags,
                    },
                )
                .map_err(|err| anyhow!("failed to record .eh_frame relocation: {err}"))?;
        }
        Ok(())
    }
}

struct EhFrameSection {