Merge pull request #20908 from ziglang/reorg-std.debug-again

std.debug: reorg and clarify API goals

1 files changed, 2438 insertions, 0 deletions

diff --git a/lib/std/debug/SelfInfo.zig b/lib/std/debug/SelfInfo.zig
new file mode 100644
index 0000000000..c27f466fb3
--- /dev/null
+++ b/lib/std/debug/SelfInfo.zig
@@ -0,0 +1,2438 @@
+//! Cross-platform abstraction for this binary's own debug information, with a
+//! goal of minimal code bloat and compilation speed penalty.
+
+const builtin = @import("builtin");
+const native_os = builtin.os.tag;
+const native_endian = native_arch.endian();
+const native_arch = builtin.cpu.arch;
+
+const std = @import("../std.zig");
+const mem = std.mem;
+const Allocator = std.mem.Allocator;
+const windows = std.os.windows;
+const macho = std.macho;
+const fs = std.fs;
+const coff = std.coff;
+const pdb = std.pdb;
+const assert = std.debug.assert;
+const posix = std.posix;
+const elf = std.elf;
+const Dwarf = std.debug.Dwarf;
+const Pdb = std.debug.Pdb;
+const File = std.fs.File;
+const math = std.math;
+const testing = std.testing;
+const StackIterator = std.debug.StackIterator;
+const regBytes = Dwarf.abi.regBytes;
+const regValueNative = Dwarf.abi.regValueNative;
+
+const SelfInfo = @This();
+
+const root = @import("root");
+
+allocator: Allocator,
+address_map: std.AutoHashMap(usize, *Module),
+modules: if (native_os == .windows) std.ArrayListUnmanaged(WindowsModule) else void,
+
+pub const OpenError = error{
+    MissingDebugInfo,
+    UnsupportedOperatingSystem,
+} || @typeInfo(@typeInfo(@TypeOf(SelfInfo.init)).Fn.return_type.?).ErrorUnion.error_set;
+
+pub fn open(allocator: Allocator) OpenError!SelfInfo {
+    nosuspend {
+        if (builtin.strip_debug_info)
+            return error.MissingDebugInfo;
+        switch (native_os) {
+            .linux,
+            .freebsd,
+            .netbsd,
+            .dragonfly,
+            .openbsd,
+            .macos,
+            .solaris,
+            .illumos,
+            .windows,
+            => return try SelfInfo.init(allocator),
+            else => return error.UnsupportedOperatingSystem,
+        }
+    }
+}
+
+pub fn init(allocator: Allocator) !SelfInfo {
+    var debug_info: SelfInfo = .{
+        .allocator = allocator,
+        .address_map = std.AutoHashMap(usize, *Module).init(allocator),
+        .modules = if (native_os == .windows) .{} else {},
+    };
+
+    if (native_os == .windows) {
+        errdefer debug_info.modules.deinit(allocator);
+
+        const handle = windows.kernel32.CreateToolhelp32Snapshot(windows.TH32CS_SNAPMODULE | windows.TH32CS_SNAPMODULE32, 0);
+        if (handle == windows.INVALID_HANDLE_VALUE) {
+            switch (windows.GetLastError()) {
+                else => |err| return windows.unexpectedError(err),
+            }
+        }
+        defer windows.CloseHandle(handle);
+
+        var module_entry: windows.MODULEENTRY32 = undefined;
+        module_entry.dwSize = @sizeOf(windows.MODULEENTRY32);
+        if (windows.kernel32.Module32First(handle, &module_entry) == 0) {
+            return error.MissingDebugInfo;
+        }
+
+        var module_valid = true;
+        while (module_valid) {
+            const module_info = try debug_info.modules.addOne(allocator);
+            const name = allocator.dupe(u8, mem.sliceTo(&module_entry.szModule, 0)) catch &.{};
+            errdefer allocator.free(name);
+
+            module_info.* = .{
+                .base_address = @intFromPtr(module_entry.modBaseAddr),
+                .size = module_entry.modBaseSize,
+                .name = name,
+                .handle = module_entry.hModule,
+            };
+
+            module_valid = windows.kernel32.Module32Next(handle, &module_entry) == 1;
+        }
+    }
+
+    return debug_info;
+}
+
+pub fn deinit(self: *SelfInfo) void {
+    var it = self.address_map.iterator();
+    while (it.next()) |entry| {
+        const mdi = entry.value_ptr.*;
+        mdi.deinit(self.allocator);
+        self.allocator.destroy(mdi);
+    }
+    self.address_map.deinit();
+    if (native_os == .windows) {
+        for (self.modules.items) |module| {
+            self.allocator.free(module.name);
+            if (module.mapped_file) |mapped_file| mapped_file.deinit();
+        }
+        self.modules.deinit(self.allocator);
+    }
+}
+
+pub fn getModuleForAddress(self: *SelfInfo, address: usize) !*Module {
+    if (comptime builtin.target.isDarwin()) {
+        return self.lookupModuleDyld(address);
+    } else if (native_os == .windows) {
+        return self.lookupModuleWin32(address);
+    } else if (native_os == .haiku) {
+        return self.lookupModuleHaiku(address);
+    } else if (comptime builtin.target.isWasm()) {
+        return self.lookupModuleWasm(address);
+    } else {
+        return self.lookupModuleDl(address);
+    }
+}
+
+// Returns the module name for a given address.
+// This can be called when getModuleForAddress fails, so implementations should provide
+// a path that doesn't rely on any side-effects of a prior successful module lookup.
+pub fn getModuleNameForAddress(self: *SelfInfo, address: usize) ?[]const u8 {
+    if (comptime builtin.target.isDarwin()) {
+        return self.lookupModuleNameDyld(address);
+    } else if (native_os == .windows) {
+        return self.lookupModuleNameWin32(address);
+    } else if (native_os == .haiku) {
+        return null;
+    } else if (comptime builtin.target.isWasm()) {
+        return null;
+    } else {
+        return self.lookupModuleNameDl(address);
+    }
+}
+
+fn lookupModuleDyld(self: *SelfInfo, address: usize) !*Module {
+    const image_count = std.c._dyld_image_count();
+
+    var i: u32 = 0;
+    while (i < image_count) : (i += 1) {
+        const header = std.c._dyld_get_image_header(i) orelse continue;
+        const base_address = @intFromPtr(header);
+        if (address < base_address) continue;
+        const vmaddr_slide = std.c._dyld_get_image_vmaddr_slide(i);
+
+        var it = macho.LoadCommandIterator{
+            .ncmds = header.ncmds,
+            .buffer = @alignCast(@as(
+                [*]u8,
+                @ptrFromInt(@intFromPtr(header) + @sizeOf(macho.mach_header_64)),
+            )[0..header.sizeofcmds]),
+        };
+
+        var unwind_info: ?[]const u8 = null;
+        var eh_frame: ?[]const u8 = null;
+        while (it.next()) |cmd| switch (cmd.cmd()) {
+            .SEGMENT_64 => {
+                const segment_cmd = cmd.cast(macho.segment_command_64).?;
+                if (!mem.eql(u8, "__TEXT", segment_cmd.segName())) continue;
+
+                const seg_start = segment_cmd.vmaddr + vmaddr_slide;
+                const seg_end = seg_start + segment_cmd.vmsize;
+                if (address >= seg_start and address < seg_end) {
+                    if (self.address_map.get(base_address)) |obj_di| {
+                        return obj_di;
+                    }
+
+                    for (cmd.getSections()) |sect| {
+                        if (mem.eql(u8, "__unwind_info", sect.sectName())) {
+                            unwind_info = @as([*]const u8, @ptrFromInt(sect.addr + vmaddr_slide))[0..sect.size];
+                        } else if (mem.eql(u8, "__eh_frame", sect.sectName())) {
+                            eh_frame = @as([*]const u8, @ptrFromInt(sect.addr + vmaddr_slide))[0..sect.size];
+                        }
+                    }
+
+                    const obj_di = try self.allocator.create(Module);
+                    errdefer self.allocator.destroy(obj_di);
+
+                    const macho_path = mem.sliceTo(std.c._dyld_get_image_name(i), 0);
+                    const macho_file = fs.cwd().openFile(macho_path, .{}) catch |err| switch (err) {
+                        error.FileNotFound => return error.MissingDebugInfo,
+                        else => return err,
+                    };
+                    obj_di.* = try readMachODebugInfo(self.allocator, macho_file);
+                    obj_di.base_address = base_address;
+                    obj_di.vmaddr_slide = vmaddr_slide;
+                    obj_di.unwind_info = unwind_info;
+                    obj_di.eh_frame = eh_frame;
+
+                    try self.address_map.putNoClobber(base_address, obj_di);
+
+                    return obj_di;
+                }
+            },
+            else => {},
+        };
+    }
+
+    return error.MissingDebugInfo;
+}
+
+fn lookupModuleNameDyld(self: *SelfInfo, address: usize) ?[]const u8 {
+    _ = self;
+    const image_count = std.c._dyld_image_count();
+
+    var i: u32 = 0;
+    while (i < image_count) : (i += 1) {
+        const header = std.c._dyld_get_image_header(i) orelse continue;
+        const base_address = @intFromPtr(header);
+        if (address < base_address) continue;
+        const vmaddr_slide = std.c._dyld_get_image_vmaddr_slide(i);
+
+        var it = macho.LoadCommandIterator{
+            .ncmds = header.ncmds,
+            .buffer = @alignCast(@as(
+                [*]u8,
+                @ptrFromInt(@intFromPtr(header) + @sizeOf(macho.mach_header_64)),
+            )[0..header.sizeofcmds]),
+        };
+
+        while (it.next()) |cmd| switch (cmd.cmd()) {
+            .SEGMENT_64 => {
+                const segment_cmd = cmd.cast(macho.segment_command_64).?;
+                if (!mem.eql(u8, "__TEXT", segment_cmd.segName())) continue;
+
+                const original_address = address - vmaddr_slide;
+                const seg_start = segment_cmd.vmaddr;
+                const seg_end = seg_start + segment_cmd.vmsize;
+                if (original_address >= seg_start and original_address < seg_end) {
+                    return fs.path.basename(mem.sliceTo(std.c._dyld_get_image_name(i), 0));
+                }
+            },
+            else => {},
+        };
+    }
+
+    return null;
+}
+
+fn lookupModuleWin32(self: *SelfInfo, address: usize) !*Module {
+    for (self.modules.items) |*module| {
+        if (address >= module.base_address and address < module.base_address + module.size) {
+            if (self.address_map.get(module.base_address)) |obj_di| {
+                return obj_di;
+            }
+
+            const obj_di = try self.allocator.create(Module);
+            errdefer self.allocator.destroy(obj_di);
+
+            const mapped_module = @as([*]const u8, @ptrFromInt(module.base_address))[0..module.size];
+            var coff_obj = try coff.Coff.init(mapped_module, true);
+
+            // The string table is not mapped into memory by the loader, so if a section name is in the
+            // string table then we have to map the full image file from disk. This can happen when
+            // a binary is produced with -gdwarf, since the section names are longer than 8 bytes.
+            if (coff_obj.strtabRequired()) {
+                var name_buffer: [windows.PATH_MAX_WIDE + 4:0]u16 = undefined;
+                // openFileAbsoluteW requires the prefix to be present
+                @memcpy(name_buffer[0..4], &[_]u16{ '\\', '?', '?', '\\' });
+
+                const process_handle = windows.GetCurrentProcess();
+                const len = windows.kernel32.GetModuleFileNameExW(
+                    process_handle,
+                    module.handle,
+                    @ptrCast(&name_buffer[4]),
+                    windows.PATH_MAX_WIDE,
+                );
+
+                if (len == 0) return error.MissingDebugInfo;
+                const coff_file = fs.openFileAbsoluteW(name_buffer[0 .. len + 4 :0], .{}) catch |err| switch (err) {
+                    error.FileNotFound => return error.MissingDebugInfo,
+                    else => return err,
+                };
+                errdefer coff_file.close();
+
+                var section_handle: windows.HANDLE = undefined;
+                const create_section_rc = windows.ntdll.NtCreateSection(
+                    &section_handle,
+                    windows.STANDARD_RIGHTS_REQUIRED | windows.SECTION_QUERY | windows.SECTION_MAP_READ,
+                    null,
+                    null,
+                    windows.PAGE_READONLY,
+                    // The documentation states that if no AllocationAttribute is specified, then SEC_COMMIT is the default.
+                    // In practice, this isn't the case and specifying 0 will result in INVALID_PARAMETER_6.
+                    windows.SEC_COMMIT,
+                    coff_file.handle,
+                );
+                if (create_section_rc != .SUCCESS) return error.MissingDebugInfo;
+                errdefer windows.CloseHandle(section_handle);
+
+                var coff_len: usize = 0;
+                var base_ptr: usize = 0;
+                const map_section_rc = windows.ntdll.NtMapViewOfSection(
+                    section_handle,
+                    process_handle,
+                    @ptrCast(&base_ptr),
+                    null,
+                    0,
+                    null,
+                    &coff_len,
+                    .ViewUnmap,
+                    0,
+                    windows.PAGE_READONLY,
+                );
+                if (map_section_rc != .SUCCESS) return error.MissingDebugInfo;
+                errdefer assert(windows.ntdll.NtUnmapViewOfSection(process_handle, @ptrFromInt(base_ptr)) == .SUCCESS);
+
+                const section_view = @as([*]const u8, @ptrFromInt(base_ptr))[0..coff_len];
+                coff_obj = try coff.Coff.init(section_view, false);
+
+                module.mapped_file = .{
+                    .file = coff_file,
+                    .section_handle = section_handle,
+                    .section_view = section_view,
+                };
+            }
+            errdefer if (module.mapped_file) |mapped_file| mapped_file.deinit();
+
+            obj_di.* = try readCoffDebugInfo(self.allocator, &coff_obj);
+            obj_di.base_address = module.base_address;
+
+            try self.address_map.putNoClobber(module.base_address, obj_di);
+            return obj_di;
+        }
+    }
+
+    return error.MissingDebugInfo;
+}
+
+fn lookupModuleNameWin32(self: *SelfInfo, address: usize) ?[]const u8 {
+    for (self.modules.items) |module| {
+        if (address >= module.base_address and address < module.base_address + module.size) {
+            return module.name;
+        }
+    }
+    return null;
+}
+
+fn lookupModuleNameDl(self: *SelfInfo, address: usize) ?[]const u8 {
+    _ = self;
+
+    var ctx: struct {
+        // Input
+        address: usize,
+        // Output
+        name: []const u8 = "",
+    } = .{ .address = address };
+    const CtxTy = @TypeOf(ctx);
+
+    if (posix.dl_iterate_phdr(&ctx, error{Found}, struct {
+        fn callback(info: *posix.dl_phdr_info, size: usize, context: *CtxTy) !void {
+            _ = size;
+            if (context.address < info.addr) return;
+            const phdrs = info.phdr[0..info.phnum];
+            for (phdrs) |*phdr| {
+                if (phdr.p_type != elf.PT_LOAD) continue;
+
+                const seg_start = info.addr +% phdr.p_vaddr;
+                const seg_end = seg_start + phdr.p_memsz;
+                if (context.address >= seg_start and context.address < seg_end) {
+                    context.name = mem.sliceTo(info.name, 0) orelse "";
+                    break;
+                }
+            } else return;
+
+            return error.Found;
+        }
+    }.callback)) {
+        return null;
+    } else |err| switch (err) {
+        error.Found => return fs.path.basename(ctx.name),
+    }
+
+    return null;
+}
+
+fn lookupModuleDl(self: *SelfInfo, address: usize) !*Module {
+    var ctx: struct {
+        // Input
+        address: usize,
+        // Output
+        base_address: usize = undefined,
+        name: []const u8 = undefined,
+        build_id: ?[]const u8 = null,
+        gnu_eh_frame: ?[]const u8 = null,
+    } = .{ .address = address };
+    const CtxTy = @TypeOf(ctx);
+
+    if (posix.dl_iterate_phdr(&ctx, error{Found}, struct {
+        fn callback(info: *posix.dl_phdr_info, size: usize, context: *CtxTy) !void {
+            _ = size;
+            // The base address is too high
+            if (context.address < info.addr)
+                return;
+
+            const phdrs = info.phdr[0..info.phnum];
+            for (phdrs) |*phdr| {
+                if (phdr.p_type != elf.PT_LOAD) continue;
+
+                // Overflowing addition is used to handle the case of VSDOs having a p_vaddr = 0xffffffffff700000
+                const seg_start = info.addr +% phdr.p_vaddr;
+                const seg_end = seg_start + phdr.p_memsz;
+                if (context.address >= seg_start and context.address < seg_end) {
+                    // Android libc uses NULL instead of an empty string to mark the
+                    // main program
+                    context.name = mem.sliceTo(info.name, 0) orelse "";
+                    context.base_address = info.addr;
+                    break;
+                }
+            } else return;
+
+            for (info.phdr[0..info.phnum]) |phdr| {
+                switch (phdr.p_type) {
+                    elf.PT_NOTE => {
+                        // Look for .note.gnu.build-id
+                        const note_bytes = @as([*]const u8, @ptrFromInt(info.addr + phdr.p_vaddr))[0..phdr.p_memsz];
+                        const name_size = mem.readInt(u32, note_bytes[0..4], native_endian);
+                        if (name_size != 4) continue;
+                        const desc_size = mem.readInt(u32, note_bytes[4..8], native_endian);
+                        const note_type = mem.readInt(u32, note_bytes[8..12], native_endian);
+                        if (note_type != elf.NT_GNU_BUILD_ID) continue;
+                        if (!mem.eql(u8, "GNU\x00", note_bytes[12..16])) continue;
+                        context.build_id = note_bytes[16..][0..desc_size];
+                    },
+                    elf.PT_GNU_EH_FRAME => {
+                        context.gnu_eh_frame = @as([*]const u8, @ptrFromInt(info.addr + phdr.p_vaddr))[0..phdr.p_memsz];
+                    },
+                    else => {},
+                }
+            }
+
+            // Stop the iteration
+            return error.Found;
+        }
+    }.callback)) {
+        return error.MissingDebugInfo;
+    } else |err| switch (err) {
+        error.Found => {},
+    }
+
+    if (self.address_map.get(ctx.base_address)) |obj_di| {
+        return obj_di;
+    }
+
+    const obj_di = try self.allocator.create(Module);
+    errdefer self.allocator.destroy(obj_di);
+
+    var sections: Dwarf.SectionArray = Dwarf.null_section_array;
+    if (ctx.gnu_eh_frame) |eh_frame_hdr| {
+        // This is a special case - pointer offsets inside .eh_frame_hdr
+        // are encoded relative to its base address, so we must use the
+        // version that is already memory mapped, and not the one that
+        // will be mapped separately from the ELF file.
+        sections[@intFromEnum(Dwarf.Section.Id.eh_frame_hdr)] = .{
+            .data = eh_frame_hdr,
+            .owned = false,
+        };
+    }
+
+    obj_di.* = try readElfDebugInfo(self.allocator, if (ctx.name.len > 0) ctx.name else null, ctx.build_id, null, &sections, null);
+    obj_di.base_address = ctx.base_address;
+
+    // Missing unwind info isn't treated as a failure, as the unwinder will fall back to FP-based unwinding
+    obj_di.dwarf.scanAllUnwindInfo(self.allocator, ctx.base_address) catch {};
+
+    try self.address_map.putNoClobber(ctx.base_address, obj_di);
+
+    return obj_di;
+}
+
+fn lookupModuleHaiku(self: *SelfInfo, address: usize) !*Module {
+    _ = self;
+    _ = address;
+    @panic("TODO implement lookup module for Haiku");
+}
+
+fn lookupModuleWasm(self: *SelfInfo, address: usize) !*Module {
+    _ = self;
+    _ = address;
+    @panic("TODO implement lookup module for Wasm");
+}
+
+pub const Module = switch (native_os) {
+    .macos, .ios, .watchos, .tvos, .visionos => struct {
+        base_address: usize,
+        vmaddr_slide: usize,
+        mapped_memory: []align(mem.page_size) const u8,
+        symbols: []const MachoSymbol,
+        strings: [:0]const u8,
+        ofiles: OFileTable,
+
+        // Backed by the in-memory sections mapped by the loader
+        unwind_info: ?[]const u8 = null,
+        eh_frame: ?[]const u8 = null,
+
+        const OFileTable = std.StringHashMap(OFileInfo);
+        const OFileInfo = struct {
+            di: Dwarf,
+            addr_table: std.StringHashMap(u64),
+        };
+
+        pub fn deinit(self: *@This(), allocator: Allocator) void {
+            var it = self.ofiles.iterator();
+            while (it.next()) |entry| {
+                const ofile = entry.value_ptr;
+                ofile.di.deinit(allocator);
+                ofile.addr_table.deinit();
+            }
+            self.ofiles.deinit();
+            allocator.free(self.symbols);
+            posix.munmap(self.mapped_memory);
+        }
+
+        fn loadOFile(self: *@This(), allocator: Allocator, o_file_path: []const u8) !*OFileInfo {
+            const o_file = try fs.cwd().openFile(o_file_path, .{});
+            const mapped_mem = try mapWholeFile(o_file);
+
+            const hdr: *const macho.mach_header_64 = @ptrCast(@alignCast(mapped_mem.ptr));
+            if (hdr.magic != std.macho.MH_MAGIC_64)
+                return error.InvalidDebugInfo;
+
+            var segcmd: ?macho.LoadCommandIterator.LoadCommand = null;
+            var symtabcmd: ?macho.symtab_command = null;
+            var it = macho.LoadCommandIterator{
+                .ncmds = hdr.ncmds,
+                .buffer = mapped_mem[@sizeOf(macho.mach_header_64)..][0..hdr.sizeofcmds],
+            };
+            while (it.next()) |cmd| switch (cmd.cmd()) {
+                .SEGMENT_64 => segcmd = cmd,
+                .SYMTAB => symtabcmd = cmd.cast(macho.symtab_command).?,
+                else => {},
+            };
+
+            if (segcmd == null or symtabcmd == null) return error.MissingDebugInfo;
+
+            // Parse symbols
+            const strtab = @as(
+                [*]const u8,
+                @ptrCast(&mapped_mem[symtabcmd.?.stroff]),
+            )[0 .. symtabcmd.?.strsize - 1 :0];
+            const symtab = @as(
+                [*]const macho.nlist_64,
+                @ptrCast(@alignCast(&mapped_mem[symtabcmd.?.symoff])),
+            )[0..symtabcmd.?.nsyms];
+
+            // TODO handle tentative (common) symbols
+            var addr_table = std.StringHashMap(u64).init(allocator);
+            try addr_table.ensureTotalCapacity(@as(u32, @intCast(symtab.len)));
+            for (symtab) |sym| {
+                if (sym.n_strx == 0) continue;
+                if (sym.undf() or sym.tentative() or sym.abs()) continue;
+                const sym_name = mem.sliceTo(strtab[sym.n_strx..], 0);
+                // TODO is it possible to have a symbol collision?
+                addr_table.putAssumeCapacityNoClobber(sym_name, sym.n_value);
+            }
+
+            var sections: Dwarf.SectionArray = Dwarf.null_section_array;
+            if (self.eh_frame) |eh_frame| sections[@intFromEnum(Dwarf.Section.Id.eh_frame)] = .{
+                .data = eh_frame,
+                .owned = false,
+            };
+
+            for (segcmd.?.getSections()) |sect| {
+                if (!std.mem.eql(u8, "__DWARF", sect.segName())) continue;
+
+                var section_index: ?usize = null;
+                inline for (@typeInfo(Dwarf.Section.Id).Enum.fields, 0..) |section, i| {
+                    if (mem.eql(u8, "__" ++ section.name, sect.sectName())) section_index = i;
+                }
+                if (section_index == null) continue;
+
+                const section_bytes = try chopSlice(mapped_mem, sect.offset, sect.size);
+                sections[section_index.?] = .{
+                    .data = section_bytes,
+                    .virtual_address = sect.addr,
+                    .owned = false,
+                };
+            }
+
+            const missing_debug_info =
+                sections[@intFromEnum(Dwarf.Section.Id.debug_info)] == null or
+                sections[@intFromEnum(Dwarf.Section.Id.debug_abbrev)] == null or
+                sections[@intFromEnum(Dwarf.Section.Id.debug_str)] == null or
+                sections[@intFromEnum(Dwarf.Section.Id.debug_line)] == null;
+            if (missing_debug_info) return error.MissingDebugInfo;
+
+            var di = Dwarf{
+                .endian = .little,
+                .sections = sections,
+                .is_macho = true,
+            };
+
+            try Dwarf.open(&di, allocator);
+            const info = OFileInfo{
+                .di = di,
+                .addr_table = addr_table,
+            };
+
+            // Add the debug info to the cache
+            const result = try self.ofiles.getOrPut(o_file_path);
+            assert(!result.found_existing);
+            result.value_ptr.* = info;
+
+            return result.value_ptr;
+        }
+
+        pub fn getSymbolAtAddress(self: *@This(), allocator: Allocator, address: usize) !SymbolInfo {
+            nosuspend {
+                const result = try self.getOFileInfoForAddress(allocator, address);
+                if (result.symbol == null) return .{};
+
+                // Take the symbol name from the N_FUN STAB entry, we're going to
+                // use it if we fail to find the DWARF infos
+                const stab_symbol = mem.sliceTo(self.strings[result.symbol.?.strx..], 0);
+                if (result.o_file_info == null) return .{ .symbol_name = stab_symbol };
+
+                // Translate again the address, this time into an address inside the
+                // .o file
+                const relocated_address_o = result.o_file_info.?.addr_table.get(stab_symbol) orelse return .{
+                    .symbol_name = "???",
+                };
+
+                const addr_off = result.relocated_address - result.symbol.?.addr;
+                const o_file_di = &result.o_file_info.?.di;
+                if (o_file_di.findCompileUnit(relocated_address_o)) |compile_unit| {
+                    return SymbolInfo{
+                        .symbol_name = o_file_di.getSymbolName(relocated_address_o) orelse "???",
+                        .compile_unit_name = compile_unit.die.getAttrString(
+                            o_file_di,
+                            std.dwarf.AT.name,
+                            o_file_di.section(.debug_str),
+                            compile_unit.*,
+                        ) catch |err| switch (err) {
+                            error.MissingDebugInfo, error.InvalidDebugInfo => "???",
+                        },
+                        .line_info = o_file_di.getLineNumberInfo(
+                            allocator,
+                            compile_unit.*,
+                            relocated_address_o + addr_off,
+                        ) catch |err| switch (err) {
+                            error.MissingDebugInfo, error.InvalidDebugInfo => null,
+                            else => return err,
+                        },
+                    };
+                } else |err| switch (err) {
+                    error.MissingDebugInfo, error.InvalidDebugInfo => {
+                        return SymbolInfo{ .symbol_name = stab_symbol };
+                    },
+                    else => return err,
+                }
+            }
+        }
+
+        pub fn getOFileInfoForAddress(self: *@This(), allocator: Allocator, address: usize) !struct {
+            relocated_address: usize,
+            symbol: ?*const MachoSymbol = null,
+            o_file_info: ?*OFileInfo = null,
+        } {
+            nosuspend {
+                // Translate the VA into an address into this object
+                const relocated_address = address - self.vmaddr_slide;
+
+                // Find the .o file where this symbol is defined
+                const symbol = machoSearchSymbols(self.symbols, relocated_address) orelse return .{
+                    .relocated_address = relocated_address,
+                };
+
+                // Check if its debug infos are already in the cache
+                const o_file_path = mem.sliceTo(self.strings[symbol.ofile..], 0);
+                const o_file_info = self.ofiles.getPtr(o_file_path) orelse
+                    (self.loadOFile(allocator, o_file_path) catch |err| switch (err) {
+                    error.FileNotFound,
+                    error.MissingDebugInfo,
+                    error.InvalidDebugInfo,
+                    => return .{
+                        .relocated_address = relocated_address,
+                        .symbol = symbol,
+                    },
+                    else => return err,
+                });
+
+                return .{
+                    .relocated_address = relocated_address,
+                    .symbol = symbol,
+                    .o_file_info = o_file_info,
+                };
+            }
+        }
+
+        pub fn getDwarfInfoForAddress(self: *@This(), allocator: Allocator, address: usize) !?*const Dwarf {
+            return if ((try self.getOFileInfoForAddress(allocator, address)).o_file_info) |o_file_info| &o_file_info.di else null;
+        }
+    },
+    .uefi, .windows => struct {
+        base_address: usize,
+        pdb: ?Pdb = null,
+        dwarf: ?Dwarf = null,
+        coff_image_base: u64,
+
+        /// Only used if pdb is non-null
+        coff_section_headers: []coff.SectionHeader,
+
+        pub fn deinit(self: *@This(), allocator: Allocator) void {
+            if (self.dwarf) |*dwarf| {
+                dwarf.deinit(allocator);
+            }
+
+            if (self.pdb) |*p| {
+                p.deinit();
+                allocator.free(self.coff_section_headers);
+            }
+        }
+
+        fn getSymbolFromPdb(self: *@This(), relocated_address: usize) !?SymbolInfo {
+            var coff_section: *align(1) const coff.SectionHeader = undefined;
+            const mod_index = for (self.pdb.?.sect_contribs) |sect_contrib| {
+                if (sect_contrib.Section > self.coff_section_headers.len) continue;
+                // Remember that SectionContribEntry.Section is 1-based.
+                coff_section = &self.coff_section_headers[sect_contrib.Section - 1];
+
+                const vaddr_start = coff_section.virtual_address + sect_contrib.Offset;
+                const vaddr_end = vaddr_start + sect_contrib.Size;
+                if (relocated_address >= vaddr_start and relocated_address < vaddr_end) {
+                    break sect_contrib.ModuleIndex;
+                }
+            } else {
+                // we have no information to add to the address
+                return null;
+            };
+
+            const module = (try self.pdb.?.getModule(mod_index)) orelse
+                return error.InvalidDebugInfo;
+            const obj_basename = fs.path.basename(module.obj_file_name);
+
+            const symbol_name = self.pdb.?.getSymbolName(
+                module,
+                relocated_address - coff_section.virtual_address,
+            ) orelse "???";
+            const opt_line_info = try self.pdb.?.getLineNumberInfo(
+                module,
+                relocated_address - coff_section.virtual_address,
+            );
+
+            return SymbolInfo{
+                .symbol_name = symbol_name,
+                .compile_unit_name = obj_basename,
+                .line_info = opt_line_info,
+            };
+        }
+
+        pub fn getSymbolAtAddress(self: *@This(), allocator: Allocator, address: usize) !SymbolInfo {
+            // Translate the VA into an address into this object
+            const relocated_address = address - self.base_address;
+
+            if (self.pdb != null) {
+                if (try self.getSymbolFromPdb(relocated_address)) |symbol| return symbol;
+            }
+
+            if (self.dwarf) |*dwarf| {
+                const dwarf_address = relocated_address + self.coff_image_base;
+                return getSymbolFromDwarf(allocator, dwarf_address, dwarf);
+            }
+
+            return SymbolInfo{};
+        }
+
+        pub fn getDwarfInfoForAddress(self: *@This(), allocator: Allocator, address: usize) !?*const Dwarf {
+            _ = allocator;
+            _ = address;
+
+            return switch (self.debug_data) {
+                .dwarf => |*dwarf| dwarf,
+                else => null,
+            };
+        }
+    },
+    .linux, .netbsd, .freebsd, .dragonfly, .openbsd, .haiku, .solaris, .illumos => struct {
+        base_address: usize,
+        dwarf: Dwarf,
+        mapped_memory: []align(mem.page_size) const u8,
+        external_mapped_memory: ?[]align(mem.page_size) const u8,
+
+        pub fn deinit(self: *@This(), allocator: Allocator) void {
+            self.dwarf.deinit(allocator);
+            posix.munmap(self.mapped_memory);
+            if (self.external_mapped_memory) |m| posix.munmap(m);
+        }
+
+        pub fn getSymbolAtAddress(self: *@This(), allocator: Allocator, address: usize) !SymbolInfo {
+            // Translate the VA into an address into this object
+            const relocated_address = address - self.base_address;
+            return getSymbolFromDwarf(allocator, relocated_address, &self.dwarf);
+        }
+
+        pub fn getDwarfInfoForAddress(self: *@This(), allocator: Allocator, address: usize) !?*const Dwarf {
+            _ = allocator;
+            _ = address;
+            return &self.dwarf;
+        }
+    },
+    .wasi, .emscripten => struct {
+        pub fn deinit(self: *@This(), allocator: Allocator) void {
+            _ = self;
+            _ = allocator;
+        }
+
+        pub fn getSymbolAtAddress(self: *@This(), allocator: Allocator, address: usize) !SymbolInfo {
+            _ = self;
+            _ = allocator;
+            _ = address;
+            return SymbolInfo{};
+        }
+
+        pub fn getDwarfInfoForAddress(self: *@This(), allocator: Allocator, address: usize) !?*const Dwarf {
+            _ = self;
+            _ = allocator;
+            _ = address;
+            return null;
+        }
+    },
+    else => Dwarf,
+};
+
+/// How is this different than `Module` when the host is Windows?
+/// Why are both stored in the `SelfInfo` struct?
+/// Boy, it sure would be nice if someone added documentation comments for this
+/// struct explaining it.
+pub const WindowsModule = struct {
+    base_address: usize,
+    size: u32,
+    name: []const u8,
+    handle: windows.HMODULE,
+
+    // Set when the image file needed to be mapped from disk
+    mapped_file: ?struct {
+        file: File,
+        section_handle: windows.HANDLE,
+        section_view: []const u8,
+
+        pub fn deinit(self: @This()) void {
+            const process_handle = windows.GetCurrentProcess();
+            assert(windows.ntdll.NtUnmapViewOfSection(process_handle, @constCast(@ptrCast(self.section_view.ptr))) == .SUCCESS);
+            windows.CloseHandle(self.section_handle);
+            self.file.close();
+        }
+    } = null,
+};
+
+/// This takes ownership of macho_file: users of this function should not close
+/// it themselves, even on error.
+/// TODO it's weird to take ownership even on error, rework this code.
+fn readMachODebugInfo(allocator: Allocator, macho_file: File) !Module {
+    const mapped_mem = try mapWholeFile(macho_file);
+
+    const hdr: *const macho.mach_header_64 = @ptrCast(@alignCast(mapped_mem.ptr));
+    if (hdr.magic != macho.MH_MAGIC_64)
+        return error.InvalidDebugInfo;
+
+    var it = macho.LoadCommandIterator{
+        .ncmds = hdr.ncmds,
+        .buffer = mapped_mem[@sizeOf(macho.mach_header_64)..][0..hdr.sizeofcmds],
+    };
+    const symtab = while (it.next()) |cmd| switch (cmd.cmd()) {
+        .SYMTAB => break cmd.cast(macho.symtab_command).?,
+        else => {},
+    } else return error.MissingDebugInfo;
+
+    const syms = @as(
+        [*]const macho.nlist_64,
+        @ptrCast(@alignCast(&mapped_mem[symtab.symoff])),
+    )[0..symtab.nsyms];
+    const strings = mapped_mem[symtab.stroff..][0 .. symtab.strsize - 1 :0];
+
+    const symbols_buf = try allocator.alloc(MachoSymbol, syms.len);
+
+    var ofile: u32 = undefined;
+    var last_sym: MachoSymbol = undefined;
+    var symbol_index: usize = 0;
+    var state: enum {
+        init,
+        oso_open,
+        oso_close,
+        bnsym,
+        fun_strx,
+        fun_size,
+        ensym,
+    } = .init;
+
+    for (syms) |*sym| {
+        if (!sym.stab()) continue;
+
+        // TODO handle globals N_GSYM, and statics N_STSYM
+        switch (sym.n_type) {
+            macho.N_OSO => {
+                switch (state) {
+                    .init, .oso_close => {
+                        state = .oso_open;
+                        ofile = sym.n_strx;
+                    },
+                    else => return error.InvalidDebugInfo,
+                }
+            },
+            macho.N_BNSYM => {
+                switch (state) {
+                    .oso_open, .ensym => {
+                        state = .bnsym;
+                        last_sym = .{
+                            .strx = 0,
+                            .addr = sym.n_value,
+                            .size = 0,
+                            .ofile = ofile,
+                        };
+                    },
+                    else => return error.InvalidDebugInfo,
+                }
+            },
+            macho.N_FUN => {
+                switch (state) {
+                    .bnsym => {
+                        state = .fun_strx;
+                        last_sym.strx = sym.n_strx;
+                    },
+                    .fun_strx => {
+                        state = .fun_size;
+                        last_sym.size = @as(u32, @intCast(sym.n_value));
+                    },
+                    else => return error.InvalidDebugInfo,
+                }
+            },
+            macho.N_ENSYM => {
+                switch (state) {
+                    .fun_size => {
+                        state = .ensym;
+                        symbols_buf[symbol_index] = last_sym;
+                        symbol_index += 1;
+                    },
+                    else => return error.InvalidDebugInfo,
+                }
+            },
+            macho.N_SO => {
+                switch (state) {
+                    .init, .oso_close => {},
+                    .oso_open, .ensym => {
+                        state = .oso_close;
+                    },
+                    else => return error.InvalidDebugInfo,
+                }
+            },
+            else => {},
+        }
+    }
+
+    switch (state) {
+        .init => return error.MissingDebugInfo,
+        .oso_close => {},
+        else => return error.InvalidDebugInfo,
+    }
+
+    const symbols = try allocator.realloc(symbols_buf, symbol_index);
+
+    // Even though lld emits symbols in ascending order, this debug code
+    // should work for programs linked in any valid way.
+    // This sort is so that we can binary search later.
+    mem.sort(MachoSymbol, symbols, {}, MachoSymbol.addressLessThan);
+
+    return .{
+        .base_address = undefined,
+        .vmaddr_slide = undefined,
+        .mapped_memory = mapped_mem,
+        .ofiles = Module.OFileTable.init(allocator),
+        .symbols = symbols,
+        .strings = strings,
+    };
+}
+
+fn readCoffDebugInfo(allocator: Allocator, coff_obj: *coff.Coff) !Module {
+    nosuspend {
+        var di: Module = .{
+            .base_address = undefined,
+            .coff_image_base = coff_obj.getImageBase(),
+            .coff_section_headers = undefined,
+        };
+
+        if (coff_obj.getSectionByName(".debug_info")) |_| {
+            // This coff file has embedded DWARF debug info
+            var sections: Dwarf.SectionArray = Dwarf.null_section_array;
+            errdefer for (sections) |section| if (section) |s| if (s.owned) allocator.free(s.data);
+
+            inline for (@typeInfo(Dwarf.Section.Id).Enum.fields, 0..) |section, i| {
+                sections[i] = if (coff_obj.getSectionByName("." ++ section.name)) |section_header| blk: {
+                    break :blk .{
+                        .data = try coff_obj.getSectionDataAlloc(section_header, allocator),
+                        .virtual_address = section_header.virtual_address,
+                        .owned = true,
+                    };
+                } else null;
+            }
+
+            var dwarf = Dwarf{
+                .endian = native_endian,
+                .sections = sections,
+                .is_macho = false,
+            };
+
+            try Dwarf.open(&dwarf, allocator);
+            di.dwarf = dwarf;
+        }
+
+        const raw_path = try coff_obj.getPdbPath() orelse return di;
+        const path = blk: {
+            if (fs.path.isAbsolute(raw_path)) {
+                break :blk raw_path;
+            } else {
+                const self_dir = try fs.selfExeDirPathAlloc(allocator);
+                defer allocator.free(self_dir);
+                break :blk try fs.path.join(allocator, &.{ self_dir, raw_path });
+            }
+        };
+        defer if (path.ptr != raw_path.ptr) allocator.free(path);
+
+        di.pdb = Pdb.init(allocator, path) catch |err| switch (err) {
+            error.FileNotFound, error.IsDir => {
+                if (di.dwarf == null) return error.MissingDebugInfo;
+                return di;
+            },
+            else => return err,
+        };
+        try di.pdb.?.parseInfoStream();
+        try di.pdb.?.parseDbiStream();
+
+        if (!mem.eql(u8, &coff_obj.guid, &di.pdb.?.guid) or coff_obj.age != di.pdb.?.age)
+            return error.InvalidDebugInfo;
+
+        // Only used by the pdb path
+        di.coff_section_headers = try coff_obj.getSectionHeadersAlloc(allocator);
+        errdefer allocator.free(di.coff_section_headers);
+
+        return di;
+    }
+}
+
+/// Reads debug info from an ELF file, or the current binary if none in specified.
+/// If the required sections aren't present but a reference to external debug info is,
+/// then this this function will recurse to attempt to load the debug sections from
+/// an external file.
+pub fn readElfDebugInfo(
+    allocator: Allocator,
+    elf_filename: ?[]const u8,
+    build_id: ?[]const u8,
+    expected_crc: ?u32,
+    parent_sections: *Dwarf.SectionArray,
+    parent_mapped_mem: ?[]align(mem.page_size) const u8,
+) !Module {
+    nosuspend {
+        const elf_file = (if (elf_filename) |filename| blk: {
+            break :blk fs.cwd().openFile(filename, .{});
+        } else fs.openSelfExe(.{})) catch |err| switch (err) {
+            error.FileNotFound => return error.MissingDebugInfo,
+            else => return err,
+        };
+
+        const mapped_mem = try mapWholeFile(elf_file);
+        if (expected_crc) |crc| if (crc != std.hash.crc.Crc32.hash(mapped_mem)) return error.InvalidDebugInfo;
+
+        const hdr: *const elf.Ehdr = @ptrCast(&mapped_mem[0]);
+        if (!mem.eql(u8, hdr.e_ident[0..4], elf.MAGIC)) return error.InvalidElfMagic;
+        if (hdr.e_ident[elf.EI_VERSION] != 1) return error.InvalidElfVersion;
+
+        const endian: std.builtin.Endian = switch (hdr.e_ident[elf.EI_DATA]) {
+            elf.ELFDATA2LSB => .little,
+            elf.ELFDATA2MSB => .big,
+            else => return error.InvalidElfEndian,
+        };
+        assert(endian == native_endian); // this is our own debug info
+
+        const shoff = hdr.e_shoff;
+        const str_section_off = shoff + @as(u64, hdr.e_shentsize) * @as(u64, hdr.e_shstrndx);
+        const str_shdr: *const elf.Shdr = @ptrCast(@alignCast(&mapped_mem[math.cast(usize, str_section_off) orelse return error.Overflow]));
+        const header_strings = mapped_mem[str_shdr.sh_offset..][0..str_shdr.sh_size];
+        const shdrs = @as(
+            [*]const elf.Shdr,
+            @ptrCast(@alignCast(&mapped_mem[shoff])),
+        )[0..hdr.e_shnum];
+
+        var sections: Dwarf.SectionArray = Dwarf.null_section_array;
+
+        // Combine section list. This takes ownership over any owned sections from the parent scope.
+        for (parent_sections, &sections) |*parent, *section| {
+            if (parent.*) |*p| {
+                section.* = p.*;
+                p.owned = false;
+            }
+        }
+        errdefer for (sections) |section| if (section) |s| if (s.owned) allocator.free(s.data);
+
+        var separate_debug_filename: ?[]const u8 = null;
+        var separate_debug_crc: ?u32 = null;
+
+        for (shdrs) |*shdr| {
+            if (shdr.sh_type == elf.SHT_NULL or shdr.sh_type == elf.SHT_NOBITS) continue;
+            const name = mem.sliceTo(header_strings[shdr.sh_name..], 0);
+
+            if (mem.eql(u8, name, ".gnu_debuglink")) {
+                const gnu_debuglink = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
+                const debug_filename = mem.sliceTo(@as([*:0]const u8, @ptrCast(gnu_debuglink.ptr)), 0);
+                const crc_offset = mem.alignForward(usize, @intFromPtr(&debug_filename[debug_filename.len]) + 1, 4) - @intFromPtr(gnu_debuglink.ptr);
+                const crc_bytes = gnu_debuglink[crc_offset..][0..4];
+                separate_debug_crc = mem.readInt(u32, crc_bytes, native_endian);
+                separate_debug_filename = debug_filename;
+                continue;
+            }
+
+            var section_index: ?usize = null;
+            inline for (@typeInfo(Dwarf.Section.Id).Enum.fields, 0..) |section, i| {
+                if (mem.eql(u8, "." ++ section.name, name)) section_index = i;
+            }
+            if (section_index == null) continue;
+            if (sections[section_index.?] != null) continue;
+
+            const section_bytes = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
+            sections[section_index.?] = if ((shdr.sh_flags & elf.SHF_COMPRESSED) > 0) blk: {
+                var section_stream = std.io.fixedBufferStream(section_bytes);
+                var section_reader = section_stream.reader();
+                const chdr = section_reader.readStruct(elf.Chdr) catch continue;
+                if (chdr.ch_type != .ZLIB) continue;
+
+                var zlib_stream = std.compress.zlib.decompressor(section_stream.reader());
+
+                const decompressed_section = try allocator.alloc(u8, chdr.ch_size);
+                errdefer allocator.free(decompressed_section);
+
+                const read = zlib_stream.reader().readAll(decompressed_section) catch continue;
+                assert(read == decompressed_section.len);
+
+                break :blk .{
+                    .data = decompressed_section,
+                    .virtual_address = shdr.sh_addr,
+                    .owned = true,
+                };
+            } else .{
+                .data = section_bytes,
+                .virtual_address = shdr.sh_addr,
+                .owned = false,
+            };
+        }
+
+        const missing_debug_info =
+            sections[@intFromEnum(Dwarf.Section.Id.debug_info)] == null or
+            sections[@intFromEnum(Dwarf.Section.Id.debug_abbrev)] == null or
+            sections[@intFromEnum(Dwarf.Section.Id.debug_str)] == null or
+            sections[@intFromEnum(Dwarf.Section.Id.debug_line)] == null;
+
+        // Attempt to load debug info from an external file
+        // See: https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html
+        if (missing_debug_info) {
+
+            // Only allow one level of debug info nesting
+            if (parent_mapped_mem) |_| {
+                return error.MissingDebugInfo;
+            }
+
+            const global_debug_directories = [_][]const u8{
+                "/usr/lib/debug",
+            };
+
+            // <global debug directory>/.build-id/<2-character id prefix>/<id remainder>.debug
+            if (build_id) |id| blk: {
+                if (id.len < 3) break :blk;
+
+                // Either md5 (16 bytes) or sha1 (20 bytes) are used here in practice
+                const extension = ".debug";
+                var id_prefix_buf: [2]u8 = undefined;
+                var filename_buf: [38 + extension.len]u8 = undefined;
+
+                _ = std.fmt.bufPrint(&id_prefix_buf, "{s}", .{std.fmt.fmtSliceHexLower(id[0..1])}) catch unreachable;
+                const filename = std.fmt.bufPrint(
+                    &filename_buf,
+                    "{s}" ++ extension,
+                    .{std.fmt.fmtSliceHexLower(id[1..])},
+                ) catch break :blk;
+
+                for (global_debug_directories) |global_directory| {
+                    const path = try fs.path.join(allocator, &.{ global_directory, ".build-id", &id_prefix_buf, filename });
+                    defer allocator.free(path);
+
+                    return readElfDebugInfo(allocator, path, null, separate_debug_crc, &sections, mapped_mem) catch continue;
+                }
+            }
+
+            // use the path from .gnu_debuglink, in the same search order as gdb
+            if (separate_debug_filename) |separate_filename| blk: {
+                if (elf_filename != null and mem.eql(u8, elf_filename.?, separate_filename)) return error.MissingDebugInfo;
+
+                // <cwd>/<gnu_debuglink>
+                if (readElfDebugInfo(allocator, separate_filename, null, separate_debug_crc, &sections, mapped_mem)) |debug_info| return debug_info else |_| {}
+
+                // <cwd>/.debug/<gnu_debuglink>
+                {
+                    const path = try fs.path.join(allocator, &.{ ".debug", separate_filename });
+                    defer allocator.free(path);
+
+                    if (readElfDebugInfo(allocator, path, null, separate_debug_crc, &sections, mapped_mem)) |debug_info| return debug_info else |_| {}
+                }
+
+                var cwd_buf: [fs.max_path_bytes]u8 = undefined;
+                const cwd_path = posix.realpath(".", &cwd_buf) catch break :blk;
+
+                // <global debug directory>/<absolute folder of current binary>/<gnu_debuglink>
+                for (global_debug_directories) |global_directory| {
+                    const path = try fs.path.join(allocator, &.{ global_directory, cwd_path, separate_filename });
+                    defer allocator.free(path);
+                    if (readElfDebugInfo(allocator, path, null, separate_debug_crc, &sections, mapped_mem)) |debug_info| return debug_info else |_| {}
+                }
+            }
+
+            return error.MissingDebugInfo;
+        }
+
+        var di = Dwarf{
+            .endian = endian,
+            .sections = sections,
+            .is_macho = false,
+        };
+
+        try Dwarf.open(&di, allocator);
+
+        return .{
+            .base_address = undefined,
+            .dwarf = di,
+            .mapped_memory = parent_mapped_mem orelse mapped_mem,
+            .external_mapped_memory = if (parent_mapped_mem != null) mapped_mem else null,
+        };
+    }
+}
+
+const MachoSymbol = struct {
+    strx: u32,
+    addr: u64,
+    size: u32,
+    ofile: u32,
+
+    /// Returns the address from the macho file
+    fn address(self: MachoSymbol) u64 {
+        return self.addr;
+    }
+
+    fn addressLessThan(context: void, lhs: MachoSymbol, rhs: MachoSymbol) bool {
+        _ = context;
+        return lhs.addr < rhs.addr;
+    }
+};
+
+/// Takes ownership of file, even on error.
+/// TODO it's weird to take ownership even on error, rework this code.
+fn mapWholeFile(file: File) ![]align(mem.page_size) const u8 {
+    nosuspend {
+        defer file.close();
+
+        const file_len = math.cast(usize, try file.getEndPos()) orelse math.maxInt(usize);
+        const mapped_mem = try posix.mmap(
+            null,
+            file_len,
+            posix.PROT.READ,
+            .{ .TYPE = .SHARED },
+            file.handle,
+            0,
+        );
+        errdefer posix.munmap(mapped_mem);
+
+        return mapped_mem;
+    }
+}
+
+fn chopSlice(ptr: []const u8, offset: u64, size: u64) error{Overflow}![]const u8 {
+    const start = math.cast(usize, offset) orelse return error.Overflow;
+    const end = start + (math.cast(usize, size) orelse return error.Overflow);
+    return ptr[start..end];
+}
+
+pub const SymbolInfo = struct {
+    symbol_name: []const u8 = "???",
+    compile_unit_name: []const u8 = "???",
+    line_info: ?std.debug.SourceLocation = null,
+
+    pub fn deinit(self: SymbolInfo, allocator: Allocator) void {
+        if (self.line_info) |li| allocator.free(li.file_name);
+    }
+};
+
+fn machoSearchSymbols(symbols: []const MachoSymbol, address: usize) ?*const MachoSymbol {
+    var min: usize = 0;
+    var max: usize = symbols.len - 1;
+    while (min < max) {
+        const mid = min + (max - min) / 2;
+        const curr = &symbols[mid];
+        const next = &symbols[mid + 1];
+        if (address >= next.address()) {
+            min = mid + 1;
+        } else if (address < curr.address()) {
+            max = mid;
+        } else {
+            return curr;
+        }
+    }
+
+    const max_sym = &symbols[symbols.len - 1];
+    if (address >= max_sym.address())
+        return max_sym;
+
+    return null;
+}
+
+test machoSearchSymbols {
+    const symbols = [_]MachoSymbol{
+        .{ .addr = 100, .strx = undefined, .size = undefined, .ofile = undefined },
+        .{ .addr = 200, .strx = undefined, .size = undefined, .ofile = undefined },
+        .{ .addr = 300, .strx = undefined, .size = undefined, .ofile = undefined },
+    };
+
+    try testing.expectEqual(null, machoSearchSymbols(&symbols, 0));
+    try testing.expectEqual(null, machoSearchSymbols(&symbols, 99));
+    try testing.expectEqual(&symbols[0], machoSearchSymbols(&symbols, 100).?);
+    try testing.expectEqual(&symbols[0], machoSearchSymbols(&symbols, 150).?);
+    try testing.expectEqual(&symbols[0], machoSearchSymbols(&symbols, 199).?);
+
+    try testing.expectEqual(&symbols[1], machoSearchSymbols(&symbols, 200).?);
+    try testing.expectEqual(&symbols[1], machoSearchSymbols(&symbols, 250).?);
+    try testing.expectEqual(&symbols[1], machoSearchSymbols(&symbols, 299).?);
+
+    try testing.expectEqual(&symbols[2], machoSearchSymbols(&symbols, 300).?);
+    try testing.expectEqual(&symbols[2], machoSearchSymbols(&symbols, 301).?);
+    try testing.expectEqual(&symbols[2], machoSearchSymbols(&symbols, 5000).?);
+}
+
+fn getSymbolFromDwarf(allocator: Allocator, address: u64, di: *Dwarf) !SymbolInfo {
+    if (nosuspend di.findCompileUnit(address)) |compile_unit| {
+        return SymbolInfo{
+            .symbol_name = nosuspend di.getSymbolName(address) orelse "???",
+            .compile_unit_name = compile_unit.die.getAttrString(di, std.dwarf.AT.name, di.section(.debug_str), compile_unit.*) catch |err| switch (err) {
+                error.MissingDebugInfo, error.InvalidDebugInfo => "???",
+            },
+            .line_info = nosuspend di.getLineNumberInfo(allocator, compile_unit.*, address) catch |err| switch (err) {
+                error.MissingDebugInfo, error.InvalidDebugInfo => null,
+                else => return err,
+            },
+        };
+    } else |err| switch (err) {
+        error.MissingDebugInfo, error.InvalidDebugInfo => {
+            return SymbolInfo{};
+        },
+        else => return err,
+    }
+}
+
+/// Unwind a frame using MachO compact unwind info (from __unwind_info).
+/// If the compact encoding can't encode a way to unwind a frame, it will
+/// defer unwinding to DWARF, in which case `.eh_frame` will be used if available.
+pub fn unwindFrameMachO(
+    context: *UnwindContext,
+    ma: *std.debug.MemoryAccessor,
+    unwind_info: []const u8,
+    eh_frame: ?[]const u8,
+    module_base_address: usize,
+) !usize {
+    const header = std.mem.bytesAsValue(
+        macho.unwind_info_section_header,
+        unwind_info[0..@sizeOf(macho.unwind_info_section_header)],
+    );
+    const indices = std.mem.bytesAsSlice(
+        macho.unwind_info_section_header_index_entry,
+        unwind_info[header.indexSectionOffset..][0 .. header.indexCount * @sizeOf(macho.unwind_info_section_header_index_entry)],
+    );
+    if (indices.len == 0) return error.MissingUnwindInfo;
+
+    const mapped_pc = context.pc - module_base_address;
+    const second_level_index = blk: {
+        var left: usize = 0;
+        var len: usize = indices.len;
+
+        while (len > 1) {
+            const mid = left + len / 2;
+            const offset = indices[mid].functionOffset;
+            if (mapped_pc < offset) {
+                len /= 2;
+            } else {
+                left = mid;
+                if (mapped_pc == offset) break;
+                len -= len / 2;
+            }
+        }
+
+        // Last index is a sentinel containing the highest address as its functionOffset
+        if (indices[left].secondLevelPagesSectionOffset == 0) return error.MissingUnwindInfo;
+        break :blk &indices[left];
+    };
+
+    const common_encodings = std.mem.bytesAsSlice(
+        macho.compact_unwind_encoding_t,
+        unwind_info[header.commonEncodingsArraySectionOffset..][0 .. header.commonEncodingsArrayCount * @sizeOf(macho.compact_unwind_encoding_t)],
+    );
+
+    const start_offset = second_level_index.secondLevelPagesSectionOffset;
+    const kind = std.mem.bytesAsValue(
+        macho.UNWIND_SECOND_LEVEL,
+        unwind_info[start_offset..][0..@sizeOf(macho.UNWIND_SECOND_LEVEL)],
+    );
+
+    const entry: struct {
+        function_offset: usize,
+        raw_encoding: u32,
+    } = switch (kind.*) {
+        .REGULAR => blk: {
+            const page_header = std.mem.bytesAsValue(
+                macho.unwind_info_regular_second_level_page_header,
+                unwind_info[start_offset..][0..@sizeOf(macho.unwind_info_regular_second_level_page_header)],
+            );
+
+            const entries = std.mem.bytesAsSlice(
+                macho.unwind_info_regular_second_level_entry,
+                unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(macho.unwind_info_regular_second_level_entry)],
+            );
+            if (entries.len == 0) return error.InvalidUnwindInfo;
+
+            var left: usize = 0;
+            var len: usize = entries.len;
+            while (len > 1) {
+                const mid = left + len / 2;
+                const offset = entries[mid].functionOffset;
+                if (mapped_pc < offset) {
+                    len /= 2;
+                } else {
+                    left = mid;
+                    if (mapped_pc == offset) break;
+                    len -= len / 2;
+                }
+            }
+
+            break :blk .{
+                .function_offset = entries[left].functionOffset,
+                .raw_encoding = entries[left].encoding,
+            };
+        },
+        .COMPRESSED => blk: {
+            const page_header = std.mem.bytesAsValue(
+                macho.unwind_info_compressed_second_level_page_header,
+                unwind_info[start_offset..][0..@sizeOf(macho.unwind_info_compressed_second_level_page_header)],
+            );
+
+            const entries = std.mem.bytesAsSlice(
+                macho.UnwindInfoCompressedEntry,
+                unwind_info[start_offset + page_header.entryPageOffset ..][0 .. page_header.entryCount * @sizeOf(macho.UnwindInfoCompressedEntry)],
+            );
+            if (entries.len == 0) return error.InvalidUnwindInfo;
+
+            var left: usize = 0;
+            var len: usize = entries.len;
+            while (len > 1) {
+                const mid = left + len / 2;
+                const offset = second_level_index.functionOffset + entries[mid].funcOffset;
+                if (mapped_pc < offset) {
+                    len /= 2;
+                } else {
+                    left = mid;
+                    if (mapped_pc == offset) break;
+                    len -= len / 2;
+                }
+            }
+
+            const entry = entries[left];
+            const function_offset = second_level_index.functionOffset + entry.funcOffset;
+            if (entry.encodingIndex < header.commonEncodingsArrayCount) {
+                if (entry.encodingIndex >= common_encodings.len) return error.InvalidUnwindInfo;
+                break :blk .{
+                    .function_offset = function_offset,
+                    .raw_encoding = common_encodings[entry.encodingIndex],
+                };
+            } else {
+                const local_index = try math.sub(
+                    u8,
+                    entry.encodingIndex,
+                    math.cast(u8, header.commonEncodingsArrayCount) orelse return error.InvalidUnwindInfo,
+                );
+                const local_encodings = std.mem.bytesAsSlice(
+                    macho.compact_unwind_encoding_t,
+                    unwind_info[start_offset + page_header.encodingsPageOffset ..][0 .. page_header.encodingsCount * @sizeOf(macho.compact_unwind_encoding_t)],
+                );
+                if (local_index >= local_encodings.len) return error.InvalidUnwindInfo;
+                break :blk .{
+                    .function_offset = function_offset,
+                    .raw_encoding = local_encodings[local_index],
+                };
+            }
+        },
+        else => return error.InvalidUnwindInfo,
+    };
+
+    if (entry.raw_encoding == 0) return error.NoUnwindInfo;
+    const reg_context = Dwarf.abi.RegisterContext{
+        .eh_frame = false,
+        .is_macho = true,
+    };
+
+    const encoding: macho.CompactUnwindEncoding = @bitCast(entry.raw_encoding);
+    const new_ip = switch (builtin.cpu.arch) {
+        .x86_64 => switch (encoding.mode.x86_64) {
+            .OLD => return error.UnimplementedUnwindEncoding,
+            .RBP_FRAME => blk: {
+                const regs: [5]u3 = .{
+                    encoding.value.x86_64.frame.reg0,
+                    encoding.value.x86_64.frame.reg1,
+                    encoding.value.x86_64.frame.reg2,
+                    encoding.value.x86_64.frame.reg3,
+                    encoding.value.x86_64.frame.reg4,
+                };
+
+                const frame_offset = encoding.value.x86_64.frame.frame_offset * @sizeOf(usize);
+                var max_reg: usize = 0;
+                inline for (regs, 0..) |reg, i| {
+                    if (reg > 0) max_reg = i;
+                }
+
+                const fp = (try regValueNative(context.thread_context, fpRegNum(reg_context), reg_context)).*;
+                const new_sp = fp + 2 * @sizeOf(usize);
+
+                // Verify the stack range we're about to read register values from
+                if (ma.load(usize, new_sp) == null or ma.load(usize, fp - frame_offset + max_reg * @sizeOf(usize)) == null) return error.InvalidUnwindInfo;
+
+                const ip_ptr = fp + @sizeOf(usize);
+                const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
+                const new_fp = @as(*const usize, @ptrFromInt(fp)).*;
+
+                (try regValueNative(context.thread_context, fpRegNum(reg_context), reg_context)).* = new_fp;
+                (try regValueNative(context.thread_context, spRegNum(reg_context), reg_context)).* = new_sp;
+                (try regValueNative(context.thread_context, ip_reg_num, reg_context)).* = new_ip;
+
+                for (regs, 0..) |reg, i| {
+                    if (reg == 0) continue;
+                    const addr = fp - frame_offset + i * @sizeOf(usize);
+                    const reg_number = try Dwarf.compactUnwindToDwarfRegNumber(reg);
+                    (try regValueNative(context.thread_context, reg_number, reg_context)).* = @as(*const usize, @ptrFromInt(addr)).*;
+                }
+
+                break :blk new_ip;
+            },
+            .STACK_IMMD,
+            .STACK_IND,
+            => blk: {
+                const sp = (try regValueNative(context.thread_context, spRegNum(reg_context), reg_context)).*;
+                const stack_size = if (encoding.mode.x86_64 == .STACK_IMMD)
+                    @as(usize, encoding.value.x86_64.frameless.stack.direct.stack_size) * @sizeOf(usize)
+                else stack_size: {
+                    // In .STACK_IND, the stack size is inferred from the subq instruction at the beginning of the function.
+                    const sub_offset_addr =
+                        module_base_address +
+                        entry.function_offset +
+                        encoding.value.x86_64.frameless.stack.indirect.sub_offset;
+                    if (ma.load(usize, sub_offset_addr) == null) return error.InvalidUnwindInfo;
+
+                    // `sub_offset_addr` points to the offset of the literal within the instruction
+                    const sub_operand = @as(*align(1) const u32, @ptrFromInt(sub_offset_addr)).*;
+                    break :stack_size sub_operand + @sizeOf(usize) * @as(usize, encoding.value.x86_64.frameless.stack.indirect.stack_adjust);
+                };
+
+                // Decode the Lehmer-coded sequence of registers.
+                // For a description of the encoding see lib/libc/include/any-macos.13-any/mach-o/compact_unwind_encoding.h
+
+                // Decode the variable-based permutation number into its digits. Each digit represents
+                // an index into the list of register numbers that weren't yet used in the sequence at
+                // the time the digit was added.
+                const reg_count = encoding.value.x86_64.frameless.stack_reg_count;
+                const ip_ptr = if (reg_count > 0) reg_blk: {
+                    var digits: [6]u3 = undefined;
+                    var accumulator: usize = encoding.value.x86_64.frameless.stack_reg_permutation;
+                    var base: usize = 2;
+                    for (0..reg_count) |i| {
+                        const div = accumulator / base;
+                        digits[digits.len - 1 - i] = @intCast(accumulator - base * div);
+                        accumulator = div;
+                        base += 1;
+                    }
+
+                    const reg_numbers = [_]u3{ 1, 2, 3, 4, 5, 6 };
+                    var registers: [reg_numbers.len]u3 = undefined;
+                    var used_indices = [_]bool{false} ** reg_numbers.len;
+                    for (digits[digits.len - reg_count ..], 0..) |target_unused_index, i| {
+                        var unused_count: u8 = 0;
+                        const unused_index = for (used_indices, 0..) |used, index| {
+                            if (!used) {
+                                if (target_unused_index == unused_count) break index;
+                                unused_count += 1;
+                            }
+                        } else unreachable;
+
+                        registers[i] = reg_numbers[unused_index];
+                        used_indices[unused_index] = true;
+                    }
+
+                    var reg_addr = sp + stack_size - @sizeOf(usize) * @as(usize, reg_count + 1);
+                    if (ma.load(usize, reg_addr) == null) return error.InvalidUnwindInfo;
+                    for (0..reg_count) |i| {
+                        const reg_number = try Dwarf.compactUnwindToDwarfRegNumber(registers[i]);
+                        (try regValueNative(context.thread_context, reg_number, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
+                        reg_addr += @sizeOf(usize);
+                    }
+
+                    break :reg_blk reg_addr;
+                } else sp + stack_size - @sizeOf(usize);
+
+                const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
+                const new_sp = ip_ptr + @sizeOf(usize);
+                if (ma.load(usize, new_sp) == null) return error.InvalidUnwindInfo;
+
+                (try regValueNative(context.thread_context, spRegNum(reg_context), reg_context)).* = new_sp;
+                (try regValueNative(context.thread_context, ip_reg_num, reg_context)).* = new_ip;
+
+                break :blk new_ip;
+            },
+            .DWARF => {
+                return unwindFrameMachODwarf(context, ma, eh_frame orelse return error.MissingEhFrame, @intCast(encoding.value.x86_64.dwarf));
+            },
+        },
+        .aarch64 => switch (encoding.mode.arm64) {
+            .OLD => return error.UnimplementedUnwindEncoding,
+            .FRAMELESS => blk: {
+                const sp = (try regValueNative(context.thread_context, spRegNum(reg_context), reg_context)).*;
+                const new_sp = sp + encoding.value.arm64.frameless.stack_size * 16;
+                const new_ip = (try regValueNative(context.thread_context, 30, reg_context)).*;
+                if (ma.load(usize, new_sp) == null) return error.InvalidUnwindInfo;
+                (try regValueNative(context.thread_context, spRegNum(reg_context), reg_context)).* = new_sp;
+                break :blk new_ip;
+            },
+            .DWARF => {
+                return unwindFrameMachODwarf(context, ma, eh_frame orelse return error.MissingEhFrame, @intCast(encoding.value.arm64.dwarf));
+            },
+            .FRAME => blk: {
+                const fp = (try regValueNative(context.thread_context, fpRegNum(reg_context), reg_context)).*;
+                const new_sp = fp + 16;
+                const ip_ptr = fp + @sizeOf(usize);
+
+                const num_restored_pairs: usize =
+                    @popCount(@as(u5, @bitCast(encoding.value.arm64.frame.x_reg_pairs))) +
+                    @popCount(@as(u4, @bitCast(encoding.value.arm64.frame.d_reg_pairs)));
+                const min_reg_addr = fp - num_restored_pairs * 2 * @sizeOf(usize);
+
+                if (ma.load(usize, new_sp) == null or ma.load(usize, min_reg_addr) == null) return error.InvalidUnwindInfo;
+
+                var reg_addr = fp - @sizeOf(usize);
+                inline for (@typeInfo(@TypeOf(encoding.value.arm64.frame.x_reg_pairs)).Struct.fields, 0..) |field, i| {
+                    if (@field(encoding.value.arm64.frame.x_reg_pairs, field.name) != 0) {
+                        (try regValueNative(context.thread_context, 19 + i, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
+                        reg_addr += @sizeOf(usize);
+                        (try regValueNative(context.thread_context, 20 + i, reg_context)).* = @as(*const usize, @ptrFromInt(reg_addr)).*;
+                        reg_addr += @sizeOf(usize);
+                    }
+                }
+
+                inline for (@typeInfo(@TypeOf(encoding.value.arm64.frame.d_reg_pairs)).Struct.fields, 0..) |field, i| {
+                    if (@field(encoding.value.arm64.frame.d_reg_pairs, field.name) != 0) {
+                        // Only the lower half of the 128-bit V registers are restored during unwinding
+                        @memcpy(
+                            try regBytes(context.thread_context, 64 + 8 + i, context.reg_context),
+                            std.mem.asBytes(@as(*const usize, @ptrFromInt(reg_addr))),
+                        );
+                        reg_addr += @sizeOf(usize);
+                        @memcpy(
+                            try regBytes(context.thread_context, 64 + 9 + i, context.reg_context),
+                            std.mem.asBytes(@as(*const usize, @ptrFromInt(reg_addr))),
+                        );
+                        reg_addr += @sizeOf(usize);
+                    }
+                }
+
+                const new_ip = @as(*const usize, @ptrFromInt(ip_ptr)).*;
+                const new_fp = @as(*const usize, @ptrFromInt(fp)).*;
+
+                (try regValueNative(context.thread_context, fpRegNum(reg_context), reg_context)).* = new_fp;
+                (try regValueNative(context.thread_context, ip_reg_num, reg_context)).* = new_ip;
+
+                break :blk new_ip;
+            },
+        },
+        else => return error.UnimplementedArch,
+    };
+
+    context.pc = stripInstructionPtrAuthCode(new_ip);
+    if (context.pc > 0) context.pc -= 1;
+    return new_ip;
+}
+
+pub const UnwindContext = struct {
+    allocator: Allocator,
+    cfa: ?usize,
+    pc: usize,
+    thread_context: *std.debug.ThreadContext,
+    reg_context: Dwarf.abi.RegisterContext,
+    vm: VirtualMachine,
+    stack_machine: Dwarf.expression.StackMachine(.{ .call_frame_context = true }),
+
+    pub fn init(
+        allocator: Allocator,
+        thread_context: *std.debug.ThreadContext,
+    ) !UnwindContext {
+        comptime assert(supports_unwinding);
+
+        const pc = stripInstructionPtrAuthCode(
+            (try regValueNative(thread_context, ip_reg_num, null)).*,
+        );
+
+        const context_copy = try allocator.create(std.debug.ThreadContext);
+        std.debug.copyContext(thread_context, context_copy);
+
+        return .{
+            .allocator = allocator,
+            .cfa = null,
+            .pc = pc,
+            .thread_context = context_copy,
+            .reg_context = undefined,
+            .vm = .{},
+            .stack_machine = .{},
+        };
+    }
+
+    pub fn deinit(self: *UnwindContext) void {
+        self.vm.deinit(self.allocator);
+        self.stack_machine.deinit(self.allocator);
+        self.allocator.destroy(self.thread_context);
+        self.* = undefined;
+    }
+
+    pub fn getFp(self: *const UnwindContext) !usize {
+        return (try regValueNative(self.thread_context, fpRegNum(self.reg_context), self.reg_context)).*;
+    }
+};
+
+/// Some platforms use pointer authentication - the upper bits of instruction pointers contain a signature.
+/// This function clears these signature bits to make the pointer usable.
+pub inline fn stripInstructionPtrAuthCode(ptr: usize) usize {
+    if (native_arch == .aarch64) {
+        // `hint 0x07` maps to `xpaclri` (or `nop` if the hardware doesn't support it)
+        // The save / restore is because `xpaclri` operates on x30 (LR)
+        return asm (
+            \\mov x16, x30
+            \\mov x30, x15
+            \\hint 0x07
+            \\mov x15, x30
+            \\mov x30, x16
+            : [ret] "={x15}" (-> usize),
+            : [ptr] "{x15}" (ptr),
+            : "x16"
+        );
+    }
+
+    return ptr;
+}
+
+/// Unwind a stack frame using DWARF unwinding info, updating the register context.
+///
+/// If `.eh_frame_hdr` is available, it will be used to binary search for the FDE.
+/// Otherwise, a linear scan of `.eh_frame` and `.debug_frame` is done to find the FDE.
+///
+/// `explicit_fde_offset` is for cases where the FDE offset is known, such as when __unwind_info
+/// defers unwinding to DWARF. This is an offset into the `.eh_frame` section.
+pub fn unwindFrameDwarf(
+    di: *const Dwarf,
+    context: *UnwindContext,
+    ma: *std.debug.MemoryAccessor,
+    explicit_fde_offset: ?usize,
+) !usize {
+    if (!supports_unwinding) return error.UnsupportedCpuArchitecture;
+    if (context.pc == 0) return 0;
+
+    // Find the FDE and CIE
+    var cie: Dwarf.CommonInformationEntry = undefined;
+    var fde: Dwarf.FrameDescriptionEntry = undefined;
+
+    if (explicit_fde_offset) |fde_offset| {
+        const dwarf_section: Dwarf.Section.Id = .eh_frame;
+        const frame_section = di.section(dwarf_section) orelse return error.MissingFDE;
+        if (fde_offset >= frame_section.len) return error.MissingFDE;
+
+        var fbr: std.debug.DeprecatedFixedBufferReader = .{
+            .buf = frame_section,
+            .pos = fde_offset,
+            .endian = di.endian,
+        };
+
+        const fde_entry_header = try Dwarf.EntryHeader.read(&fbr, null, dwarf_section);
+        if (fde_entry_header.type != .fde) return error.MissingFDE;
+
+        const cie_offset = fde_entry_header.type.fde;
+        try fbr.seekTo(cie_offset);
+
+        fbr.endian = native_endian;
+        const cie_entry_header = try Dwarf.EntryHeader.read(&fbr, null, dwarf_section);
+        if (cie_entry_header.type != .cie) return Dwarf.bad();
+
+        cie = try Dwarf.CommonInformationEntry.parse(
+            cie_entry_header.entry_bytes,
+            0,
+            true,
+            cie_entry_header.format,
+            dwarf_section,
+            cie_entry_header.length_offset,
+            @sizeOf(usize),
+            native_endian,
+        );
+
+        fde = try Dwarf.FrameDescriptionEntry.parse(
+            fde_entry_header.entry_bytes,
+            0,
+            true,
+            cie,
+            @sizeOf(usize),
+            native_endian,
+        );
+    } else if (di.eh_frame_hdr) |header| {
+        const eh_frame_len = if (di.section(.eh_frame)) |eh_frame| eh_frame.len else null;
+        try header.findEntry(
+            ma,
+            eh_frame_len,
+            @intFromPtr(di.section(.eh_frame_hdr).?.ptr),
+            context.pc,
+            &cie,
+            &fde,
+        );
+    } else {
+        const index = std.sort.binarySearch(Dwarf.FrameDescriptionEntry, context.pc, di.fde_list.items, {}, struct {
+            pub fn compareFn(_: void, pc: usize, mid_item: Dwarf.FrameDescriptionEntry) std.math.Order {
+                if (pc < mid_item.pc_begin) return .lt;
+
+                const range_end = mid_item.pc_begin + mid_item.pc_range;
+                if (pc < range_end) return .eq;
+
+                return .gt;
+            }
+        }.compareFn);
+
+        fde = if (index) |i| di.fde_list.items[i] else return error.MissingFDE;
+        cie = di.cie_map.get(fde.cie_length_offset) orelse return error.MissingCIE;
+    }
+
+    var expression_context: Dwarf.expression.Context = .{
+        .format = cie.format,
+        .memory_accessor = ma,
+        .compile_unit = di.findCompileUnit(fde.pc_begin) catch null,
+        .thread_context = context.thread_context,
+        .reg_context = context.reg_context,
+        .cfa = context.cfa,
+    };
+
+    context.vm.reset();
+    context.reg_context.eh_frame = cie.version != 4;
+    context.reg_context.is_macho = di.is_macho;
+
+    const row = try context.vm.runToNative(context.allocator, context.pc, cie, fde);
+    context.cfa = switch (row.cfa.rule) {
+        .val_offset => |offset| blk: {
+            const register = row.cfa.register orelse return error.InvalidCFARule;
+            const value = mem.readInt(usize, (try regBytes(context.thread_context, register, context.reg_context))[0..@sizeOf(usize)], native_endian);
+            break :blk try applyOffset(value, offset);
+        },
+        .expression => |expr| blk: {
+            context.stack_machine.reset();
+            const value = try context.stack_machine.run(
+                expr,
+                context.allocator,
+                expression_context,
+                context.cfa,
+            );
+
+            if (value) |v| {
+                if (v != .generic) return error.InvalidExpressionValue;
+                break :blk v.generic;
+            } else return error.NoExpressionValue;
+        },
+        else => return error.InvalidCFARule,
+    };
+
+    if (ma.load(usize, context.cfa.?) == null) return error.InvalidCFA;
+    expression_context.cfa = context.cfa;
+
+    // Buffering the modifications is done because copying the thread context is not portable,
+    // some implementations (ie. darwin) use internal pointers to the mcontext.
+    var arena = std.heap.ArenaAllocator.init(context.allocator);
+    defer arena.deinit();
+    const update_allocator = arena.allocator();
+
+    const RegisterUpdate = struct {
+        // Backed by thread_context
+        dest: []u8,
+        // Backed by arena
+        src: []const u8,
+        prev: ?*@This(),
+    };
+
+    var update_tail: ?*RegisterUpdate = null;
+    var has_return_address = true;
+    for (context.vm.rowColumns(row)) |column| {
+        if (column.register) |register| {
+            if (register == cie.return_address_register) {
+                has_return_address = column.rule != .undefined;
+            }
+
+            const dest = try regBytes(context.thread_context, register, context.reg_context);
+            const src = try update_allocator.alloc(u8, dest.len);
+
+            const prev = update_tail;
+            update_tail = try update_allocator.create(RegisterUpdate);
+            update_tail.?.* = .{
+                .dest = dest,
+                .src = src,
+                .prev = prev,
+            };
+
+            try column.resolveValue(
+                context,
+                expression_context,
+                ma,
+                src,
+            );
+        }
+    }
+
+    // On all implemented architectures, the CFA is defined as being the previous frame's SP
+    (try regValueNative(context.thread_context, spRegNum(context.reg_context), context.reg_context)).* = context.cfa.?;
+
+    while (update_tail) |tail| {
+        @memcpy(tail.dest, tail.src);
+        update_tail = tail.prev;
+    }
+
+    if (has_return_address) {
+        context.pc = stripInstructionPtrAuthCode(mem.readInt(usize, (try regBytes(
+            context.thread_context,
+            cie.return_address_register,
+            context.reg_context,
+        ))[0..@sizeOf(usize)], native_endian));
+    } else {
+        context.pc = 0;
+    }
+
+    (try regValueNative(context.thread_context, ip_reg_num, context.reg_context)).* = context.pc;
+
+    // The call instruction will have pushed the address of the instruction that follows the call as the return address.
+    // This next instruction may be past the end of the function if the caller was `noreturn` (ie. the last instruction in
+    // the function was the call). If we were to look up an FDE entry using the return address directly, it could end up
+    // either not finding an FDE at all, or using the next FDE in the program, producing incorrect results. To prevent this,
+    // we subtract one so that the next lookup is guaranteed to land inside the
+    //
+    // The exception to this rule is signal frames, where we return execution would be returned to the instruction
+    // that triggered the handler.
+    const return_address = context.pc;
+    if (context.pc > 0 and !cie.isSignalFrame()) context.pc -= 1;
+
+    return return_address;
+}
+
+fn fpRegNum(reg_context: Dwarf.abi.RegisterContext) u8 {
+    return Dwarf.abi.fpRegNum(native_arch, reg_context);
+}
+
+fn spRegNum(reg_context: Dwarf.abi.RegisterContext) u8 {
+    return Dwarf.abi.spRegNum(native_arch, reg_context);
+}
+
+const ip_reg_num = Dwarf.abi.ipRegNum(native_arch).?;
+
+/// Tells whether unwinding for the host is implemented.
+pub const supports_unwinding = supportsUnwinding(builtin.target);
+
+comptime {
+    if (supports_unwinding) assert(Dwarf.abi.supportsUnwinding(builtin.target));
+}
+
+/// Tells whether unwinding for this target is *implemented* here in the Zig
+/// standard library.
+///
+/// See also `Dwarf.abi.supportsUnwinding` which tells whether Dwarf supports
+/// unwinding on that target *in theory*.
+pub fn supportsUnwinding(target: std.Target) bool {
+    return switch (target.cpu.arch) {
+        .x86 => switch (target.os.tag) {
+            .linux, .netbsd, .solaris, .illumos => true,
+            else => false,
+        },
+        .x86_64 => switch (target.os.tag) {
+            .linux, .netbsd, .freebsd, .openbsd, .macos, .ios, .solaris, .illumos => true,
+            else => false,
+        },
+        .arm => switch (target.os.tag) {
+            .linux => true,
+            else => false,
+        },
+        .aarch64 => switch (target.os.tag) {
+            .linux, .netbsd, .freebsd, .macos, .ios => true,
+            else => false,
+        },
+        // Unwinding is possible on other targets but this implementation does
+        // not support them...yet!
+        else => false,
+    };
+}
+
+fn unwindFrameMachODwarf(
+    context: *UnwindContext,
+    ma: *std.debug.MemoryAccessor,
+    eh_frame: []const u8,
+    fde_offset: usize,
+) !usize {
+    var di: Dwarf = .{
+        .endian = native_endian,
+        .is_macho = true,
+    };
+    defer di.deinit(context.allocator);
+
+    di.sections[@intFromEnum(Dwarf.Section.Id.eh_frame)] = .{
+        .data = eh_frame,
+        .owned = false,
+    };
+
+    return unwindFrameDwarf(&di, context, ma, fde_offset);
+}
+
+/// This is a virtual machine that runs DWARF call frame instructions.
+pub const VirtualMachine = struct {
+    /// See section 6.4.1 of the DWARF5 specification for details on each
+    const RegisterRule = union(enum) {
+        // The spec says that the default rule for each column is the undefined rule.
+        // However, it also allows ABI / compiler authors to specify alternate defaults, so
+        // there is a distinction made here.
+        default: void,
+        undefined: void,
+        same_value: void,
+        // offset(N)
+        offset: i64,
+        // val_offset(N)
+        val_offset: i64,
+        // register(R)
+        register: u8,
+        // expression(E)
+        expression: []const u8,
+        // val_expression(E)
+        val_expression: []const u8,
+        // Augmenter-defined rule
+        architectural: void,
+    };
+
+    /// Each row contains unwinding rules for a set of registers.
+    pub const Row = struct {
+        /// Offset from `FrameDescriptionEntry.pc_begin`
+        offset: u64 = 0,
+        /// Special-case column that defines the CFA (Canonical Frame Address) rule.
+        /// The register field of this column defines the register that CFA is derived from.
+        cfa: Column = .{},
+        /// The register fields in these columns define the register the rule applies to.
+        columns: ColumnRange = .{},
+        /// Indicates that the next write to any column in this row needs to copy
+        /// the backing column storage first, as it may be referenced by previous rows.
+        copy_on_write: bool = false,
+    };
+
+    pub const Column = struct {
+        register: ?u8 = null,
+        rule: RegisterRule = .{ .default = {} },
+
+        /// Resolves the register rule and places the result into `out` (see regBytes)
+        pub fn resolveValue(
+            self: Column,
+            context: *SelfInfo.UnwindContext,
+            expression_context: std.debug.Dwarf.expression.Context,
+            ma: *std.debug.MemoryAccessor,
+            out: []u8,
+        ) !void {
+            switch (self.rule) {
+                .default => {
+                    const register = self.register orelse return error.InvalidRegister;
+                    try getRegDefaultValue(register, context, out);
+                },
+                .undefined => {
+                    @memset(out, undefined);
+                },
+                .same_value => {
+                    // TODO: This copy could be eliminated if callers always copy the state then call this function to update it
+                    const register = self.register orelse return error.InvalidRegister;
+                    const src = try regBytes(context.thread_context, register, context.reg_context);
+                    if (src.len != out.len) return error.RegisterSizeMismatch;
+                    @memcpy(out, src);
+                },
+                .offset => |offset| {
+                    if (context.cfa) |cfa| {
+                        const addr = try applyOffset(cfa, offset);
+                        if (ma.load(usize, addr) == null) return error.InvalidAddress;
+                        const ptr: *const usize = @ptrFromInt(addr);
+                        mem.writeInt(usize, out[0..@sizeOf(usize)], ptr.*, native_endian);
+                    } else return error.InvalidCFA;
+                },
+                .val_offset => |offset| {
+                    if (context.cfa) |cfa| {
+                        mem.writeInt(usize, out[0..@sizeOf(usize)], try applyOffset(cfa, offset), native_endian);
+                    } else return error.InvalidCFA;
+                },
+                .register => |register| {
+                    const src = try regBytes(context.thread_context, register, context.reg_context);
+                    if (src.len != out.len) return error.RegisterSizeMismatch;
+                    @memcpy(out, try regBytes(context.thread_context, register, context.reg_context));
+                },
+                .expression => |expression| {
+                    context.stack_machine.reset();
+                    const value = try context.stack_machine.run(expression, context.allocator, expression_context, context.cfa.?);
+                    const addr = if (value) |v| blk: {
+                        if (v != .generic) return error.InvalidExpressionValue;
+                        break :blk v.generic;
+                    } else return error.NoExpressionValue;
+
+                    if (ma.load(usize, addr) == null) return error.InvalidExpressionAddress;
+                    const ptr: *usize = @ptrFromInt(addr);
+                    mem.writeInt(usize, out[0..@sizeOf(usize)], ptr.*, native_endian);
+                },
+                .val_expression => |expression| {
+                    context.stack_machine.reset();
+                    const value = try context.stack_machine.run(expression, context.allocator, expression_context, context.cfa.?);
+                    if (value) |v| {
+                        if (v != .generic) return error.InvalidExpressionValue;
+                        mem.writeInt(usize, out[0..@sizeOf(usize)], v.generic, native_endian);
+                    } else return error.NoExpressionValue;
+                },
+                .architectural => return error.UnimplementedRegisterRule,
+            }
+        }
+    };
+
+    const ColumnRange = struct {
+        /// Index into `columns` of the first column in this row.
+        start: usize = undefined,
+        len: u8 = 0,
+    };
+
+    columns: std.ArrayListUnmanaged(Column) = .{},
+    stack: std.ArrayListUnmanaged(ColumnRange) = .{},
+    current_row: Row = .{},
+
+    /// The result of executing the CIE's initial_instructions
+    cie_row: ?Row = null,
+
+    pub fn deinit(self: *VirtualMachine, allocator: std.mem.Allocator) void {
+        self.stack.deinit(allocator);
+        self.columns.deinit(allocator);
+        self.* = undefined;
+    }
+
+    pub fn reset(self: *VirtualMachine) void {
+        self.stack.clearRetainingCapacity();
+        self.columns.clearRetainingCapacity();
+        self.current_row = .{};
+        self.cie_row = null;
+    }
+
+    /// Return a slice backed by the row's non-CFA columns
+    pub fn rowColumns(self: VirtualMachine, row: Row) []Column {
+        if (row.columns.len == 0) return &.{};
+        return self.columns.items[row.columns.start..][0..row.columns.len];
+    }
+
+    /// Either retrieves or adds a column for `register` (non-CFA) in the current row.
+    fn getOrAddColumn(self: *VirtualMachine, allocator: std.mem.Allocator, register: u8) !*Column {
+        for (self.rowColumns(self.current_row)) |*c| {
+            if (c.register == register) return c;
+        }
+
+        if (self.current_row.columns.len == 0) {
+            self.current_row.columns.start = self.columns.items.len;
+        }
+        self.current_row.columns.len += 1;
+
+        const column = try self.columns.addOne(allocator);
+        column.* = .{
+            .register = register,
+        };
+
+        return column;
+    }
+
+    /// Runs the CIE instructions, then the FDE instructions. Execution halts
+    /// once the row that corresponds to `pc` is known, and the row is returned.
+    pub fn runTo(
+        self: *VirtualMachine,
+        allocator: std.mem.Allocator,
+        pc: u64,
+        cie: std.debug.Dwarf.CommonInformationEntry,
+        fde: std.debug.Dwarf.FrameDescriptionEntry,
+        addr_size_bytes: u8,
+        endian: std.builtin.Endian,
+    ) !Row {
+        assert(self.cie_row == null);
+        if (pc < fde.pc_begin or pc >= fde.pc_begin + fde.pc_range) return error.AddressOutOfRange;
+
+        var prev_row: Row = self.current_row;
+
+        var cie_stream = std.io.fixedBufferStream(cie.initial_instructions);
+        var fde_stream = std.io.fixedBufferStream(fde.instructions);
+        var streams = [_]*std.io.FixedBufferStream([]const u8){
+            &cie_stream,
+            &fde_stream,
+        };
+
+        for (&streams, 0..) |stream, i| {
+            while (stream.pos < stream.buffer.len) {
+                const instruction = try std.debug.Dwarf.call_frame.Instruction.read(stream, addr_size_bytes, endian);
+                prev_row = try self.step(allocator, cie, i == 0, instruction);
+                if (pc < fde.pc_begin + self.current_row.offset) return prev_row;
+            }
+        }
+
+        return self.current_row;
+    }
+
+    pub fn runToNative(
+        self: *VirtualMachine,
+        allocator: std.mem.Allocator,
+        pc: u64,
+        cie: std.debug.Dwarf.CommonInformationEntry,
+        fde: std.debug.Dwarf.FrameDescriptionEntry,
+    ) !Row {
+        return self.runTo(allocator, pc, cie, fde, @sizeOf(usize), native_endian);
+    }
+
+    fn resolveCopyOnWrite(self: *VirtualMachine, allocator: std.mem.Allocator) !void {
+        if (!self.current_row.copy_on_write) return;
+
+        const new_start = self.columns.items.len;
+        if (self.current_row.columns.len > 0) {
+            try self.columns.ensureUnusedCapacity(allocator, self.current_row.columns.len);
+            self.columns.appendSliceAssumeCapacity(self.rowColumns(self.current_row));
+            self.current_row.columns.start = new_start;
+        }
+    }
+
+    /// Executes a single instruction.
+    /// If this instruction is from the CIE, `is_initial` should be set.
+    /// Returns the value of `current_row` before executing this instruction.
+    pub fn step(
+        self: *VirtualMachine,
+        allocator: std.mem.Allocator,
+        cie: std.debug.Dwarf.CommonInformationEntry,
+        is_initial: bool,
+        instruction: Dwarf.call_frame.Instruction,
+    ) !Row {
+        // CIE instructions must be run before FDE instructions
+        assert(!is_initial or self.cie_row == null);
+        if (!is_initial and self.cie_row == null) {
+            self.cie_row = self.current_row;
+            self.current_row.copy_on_write = true;
+        }
+
+        const prev_row = self.current_row;
+        switch (instruction) {
+            .set_loc => |i| {
+                if (i.address <= self.current_row.offset) return error.InvalidOperation;
+                // TODO: Check cie.segment_selector_size != 0 for DWARFV4
+                self.current_row.offset = i.address;
+            },
+            inline .advance_loc,
+            .advance_loc1,
+            .advance_loc2,
+            .advance_loc4,
+            => |i| {
+                self.current_row.offset += i.delta * cie.code_alignment_factor;
+                self.current_row.copy_on_write = true;
+            },
+            inline .offset,
+            .offset_extended,
+            .offset_extended_sf,
+            => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{ .offset = @as(i64, @intCast(i.offset)) * cie.data_alignment_factor };
+            },
+            inline .restore,
+            .restore_extended,
+            => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                if (self.cie_row) |cie_row| {
+                    const column = try self.getOrAddColumn(allocator, i.register);
+                    column.rule = for (self.rowColumns(cie_row)) |cie_column| {
+                        if (cie_column.register == i.register) break cie_column.rule;
+                    } else .{ .default = {} };
+                } else return error.InvalidOperation;
+            },
+            .nop => {},
+            .undefined => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{ .undefined = {} };
+            },
+            .same_value => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{ .same_value = {} };
+            },
+            .register => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{ .register = i.target_register };
+            },
+            .remember_state => {
+                try self.stack.append(allocator, self.current_row.columns);
+                self.current_row.copy_on_write = true;
+            },
+            .restore_state => {
+                const restored_columns = self.stack.popOrNull() orelse return error.InvalidOperation;
+                self.columns.shrinkRetainingCapacity(self.columns.items.len - self.current_row.columns.len);
+                try self.columns.ensureUnusedCapacity(allocator, restored_columns.len);
+
+                self.current_row.columns.start = self.columns.items.len;
+                self.current_row.columns.len = restored_columns.len;
+                self.columns.appendSliceAssumeCapacity(self.columns.items[restored_columns.start..][0..restored_columns.len]);
+            },
+            .def_cfa => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                self.current_row.cfa = .{
+                    .register = i.register,
+                    .rule = .{ .val_offset = @intCast(i.offset) },
+                };
+            },
+            .def_cfa_sf => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                self.current_row.cfa = .{
+                    .register = i.register,
+                    .rule = .{ .val_offset = i.offset * cie.data_alignment_factor },
+                };
+            },
+            .def_cfa_register => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                if (self.current_row.cfa.register == null or self.current_row.cfa.rule != .val_offset) return error.InvalidOperation;
+                self.current_row.cfa.register = i.register;
+            },
+            .def_cfa_offset => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                if (self.current_row.cfa.register == null or self.current_row.cfa.rule != .val_offset) return error.InvalidOperation;
+                self.current_row.cfa.rule = .{
+                    .val_offset = @intCast(i.offset),
+                };
+            },
+            .def_cfa_offset_sf => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                if (self.current_row.cfa.register == null or self.current_row.cfa.rule != .val_offset) return error.InvalidOperation;
+                self.current_row.cfa.rule = .{
+                    .val_offset = i.offset * cie.data_alignment_factor,
+                };
+            },
+            .def_cfa_expression => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                self.current_row.cfa.register = undefined;
+                self.current_row.cfa.rule = .{
+                    .expression = i.block,
+                };
+            },
+            .expression => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{
+                    .expression = i.block,
+                };
+            },
+            .val_offset => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{
+                    .val_offset = @as(i64, @intCast(i.offset)) * cie.data_alignment_factor,
+                };
+            },
+            .val_offset_sf => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{
+                    .val_offset = i.offset * cie.data_alignment_factor,
+                };
+            },
+            .val_expression => |i| {
+                try self.resolveCopyOnWrite(allocator);
+                const column = try self.getOrAddColumn(allocator, i.register);
+                column.rule = .{
+                    .val_expression = i.block,
+                };
+            },
+        }
+
+        return prev_row;
+    }
+};
+
+/// Returns the ABI-defined default value this register has in the unwinding table
+/// before running any of the CIE instructions. The DWARF spec defines these as having
+/// the .undefined rule by default, but allows ABI authors to override that.
+fn getRegDefaultValue(reg_number: u8, context: *UnwindContext, out: []u8) !void {
+    switch (builtin.cpu.arch) {
+        .aarch64 => {
+            // Callee-saved registers are initialized as if they had the .same_value rule
+            if (reg_number >= 19 and reg_number <= 28) {
+                const src = try regBytes(context.thread_context, reg_number, context.reg_context);
+                if (src.len != out.len) return error.RegisterSizeMismatch;
+                @memcpy(out, src);
+                return;
+            }
+        },
+        else => {},
+    }
+
+    @memset(out, undefined);
+}
+
+/// Since register rules are applied (usually) during a panic,
+/// checked addition / subtraction is used so that we can return
+/// an error and fall back to FP-based unwinding.
+fn applyOffset(base: usize, offset: i64) !usize {
+    return if (offset >= 0)
+        try std.math.add(usize, base, @as(usize, @intCast(offset)))
+    else
+        try std.math.sub(usize, base, @as(usize, @intCast(-offset)));
+}