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Merge pull request #105 from kubkon/macho-preads
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macho: reduce heap allocations
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@kubkon
kubkon authored Jan 28, 2024
2 parents 9797926 + 79640c9 commit 0ba7dac
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Showing 12 changed files with 397 additions and 283 deletions.
2 changes: 2 additions & 0 deletions build.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ pub fn build(b: *std.Build) void {
const strip = b.option(bool, "strip", "Omit debug information");
const enable_logging = b.option(bool, "log", "Whether to enable logging") orelse (mode == .Debug);
const enable_tracy = b.option([]const u8, "tracy", "Enable Tracy integration. Supply path to Tracy source");
const tracy_callstack_depth = b.option(usize, "tracy-callstack-depth", "Set Tracy callstack depth") orelse 10;

const yaml = b.dependency("zig-yaml", .{
.target = target,
Expand All @@ -37,6 +38,7 @@ pub fn build(b: *std.Build) void {
exe.root_module.addOptions("build_options", exe_opts);
exe_opts.addOption(bool, "enable_logging", enable_logging);
exe_opts.addOption(bool, "enable_tracy", enable_tracy != null);
exe_opts.addOption(usize, "tracy_callstack_depth", tracy_callstack_depth);

if (enable_tracy) |tracy_path| {
const client_cpp = fs.path.join(
Expand Down
109 changes: 41 additions & 68 deletions src/MachO.zig
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
base: Zld,
arena: std.heap.ArenaAllocator.State,
options: Options,

dyld_info_cmd: macho.dyld_info_command = .{},
Expand Down Expand Up @@ -103,7 +102,6 @@ fn createEmpty(gpa: Allocator, options: Options, thread_pool: *ThreadPool) !*Mac
.file = undefined,
.thread_pool = thread_pool,
},
.arena = std.heap.ArenaAllocator.init(gpa).state,
.options = options,
};
return self;
Expand Down Expand Up @@ -148,8 +146,6 @@ pub fn deinit(self: *MachO) void {
self.export_trie.deinit(gpa);
self.unwind_info.deinit(gpa);
self.unwind_records.deinit(gpa);

self.arena.promote(gpa).deinit();
}

pub fn flush(self: *MachO) !void {
Expand All @@ -169,8 +165,8 @@ pub fn flush(self: *MachO) !void {
try self.symbols.append(gpa, .{});
try self.symbols_extra.append(gpa, 0);

var arena_allocator = self.arena.promote(gpa);
defer self.arena = arena_allocator.state;
var arena_allocator = std.heap.ArenaAllocator.init(gpa);
defer arena_allocator.deinit();
const arena = arena_allocator.allocator();

const syslibroot = self.options.syslibroot;
Expand Down Expand Up @@ -313,7 +309,7 @@ pub fn flush(self: *MachO) !void {

var has_parse_error = false;
for (resolved_objects.items) |obj| {
self.parsePositional(arena, obj) catch |err| {
self.parsePositional(obj) catch |err| {
has_parse_error = true;
switch (err) {
error.ParseFailed => {}, // already reported
Expand Down Expand Up @@ -582,21 +578,15 @@ fn inferCpuArchAndPlatform(self: *MachO, obj: LinkObject, platforms: anytype) !v
} else null;
}

fn validateCpuArch(self: *MachO, index: File.Index) void {
const file = self.getFile(index).?;
const cputype = switch (file) {
.object => |x| x.header.?.cputype,
.dylib => |x| x.header.?.cputype,
else => unreachable,
};
fn validateCpuArch(self: *MachO, index: File.Index, cputype: macho.cpu_type_t) void {
const cpu_arch: std.Target.Cpu.Arch = switch (cputype) {
macho.CPU_TYPE_ARM64 => .aarch64,
macho.CPU_TYPE_X86_64 => .x86_64,
else => unreachable,
};
if (self.options.cpu_arch.? != cpu_arch) {
return self.base.fatal("{}: invalid architecture '{s}', expected '{s}'", .{
file.fmtPath(),
self.getFile(index).?.fmtPath(),
@tagName(cpu_arch),
@tagName(self.options.cpu_arch.?),
});
Expand Down Expand Up @@ -661,24 +651,23 @@ fn addUndefinedGlobals(self: *MachO) !void {
}
}

fn parsePositional(self: *MachO, arena: Allocator, obj: LinkObject) !void {
fn parsePositional(self: *MachO, obj: LinkObject) !void {
log.debug("parsing positional {}", .{obj});

if (try self.parseObject(arena, obj)) return;
if (try self.parseArchive(arena, obj)) return;
if (try self.parseDylib(arena, obj, true)) |_| return;
if (try self.parseObject(obj)) return;
if (try self.parseArchive(obj)) return;
if (try self.parseDylib(obj, true)) |_| return;
if (try self.parseTbd(obj, true)) |_| return;

self.base.fatal("unknown filetype for positional argument: '{s}'", .{obj.path});
}

fn parseObject(self: *MachO, arena: Allocator, obj: LinkObject) !bool {
fn parseObject(self: *MachO, obj: LinkObject) !bool {
const tracy = trace(@src());
defer tracy.end();

const gpa = self.base.allocator;
const file = try std.fs.cwd().openFile(obj.path, .{});
defer file.close();

const header = file.reader().readStruct(macho.mach_header_64) catch return false;
try file.seekTo(0);
Expand All @@ -689,55 +678,47 @@ fn parseObject(self: *MachO, arena: Allocator, obj: LinkObject) !bool {
const stat = file.stat() catch break :mtime 0;
break :mtime @as(u64, @intCast(@divFloor(stat.mtime, 1_000_000_000)));
};
const data = try file.readToEndAlloc(arena, std.math.maxInt(u32));

const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
self.files.set(index, .{ .object = .{
.path = obj.path,
.data = data,
.path = try gpa.dupe(u8, obj.path),
.file = file,
.index = index,
.mtime = mtime,
} });
const object = &self.files.items(.data)[index].object;
try object.parse(self);
try self.objects.append(gpa, index);
self.validateCpuArch(index);
self.validateCpuArch(index, header.cputype);
self.validatePlatform(index);

return true;
}

fn parseArchive(self: *MachO, arena: Allocator, obj: LinkObject) !bool {
fn parseArchive(self: *MachO, obj: LinkObject) !bool {
const tracy = trace(@src());
defer tracy.end();

const gpa = self.base.allocator;

const file = try std.fs.cwd().openFile(obj.path, .{});
defer file.close();

var offset: u64 = 0;
var size: u64 = (try file.stat()).size;
if (fat.isFatLibrary(file)) {
const fat_arch = self.parseFatLibrary(obj.path, file) catch |err| switch (err) {
const fat_arch: ?fat.Arch = if (fat.isFatLibrary(file)) blk: {
break :blk self.parseFatLibrary(obj.path, file) catch |err| switch (err) {
error.NoArchSpecified, error.MissingArch => return false,
else => |e| return e,
};
offset = fat_arch.offset;
size = fat_arch.size;
try file.seekTo(offset);
}
} else null;
const offset = if (fat_arch) |ar| ar.offset else 0;
try file.seekTo(offset);

const magic = file.reader().readBytesNoEof(Archive.SARMAG) catch return false;
if (!mem.eql(u8, &magic, Archive.ARMAG)) return false;
try file.seekTo(0);

const data = try arena.alloc(u8, size - Archive.SARMAG);
const nread = try file.readAll(data);
if (nread != size - Archive.SARMAG) return error.InputOutput;

var archive = Archive{ .path = obj.path, .data = data };
var archive = Archive{};
defer archive.deinit(gpa);
try archive.parse(arena, self);
try archive.parse(self, obj.path, file, fat_arch);

var has_parse_error = false;
for (archive.objects.items) |extracted| {
Expand All @@ -757,7 +738,7 @@ fn parseArchive(self: *MachO, arena: Allocator, obj: LinkObject) !bool {
};
try self.objects.append(gpa, index);
// TODO this should come before reporting any parse errors
self.validateCpuArch(index);
self.validateCpuArch(index, object.header.?.cputype);
self.validatePlatform(index);

// Finally, we do a post-parse check for -ObjC to see if we need to force load this member
Expand Down Expand Up @@ -795,7 +776,7 @@ const DylibOpts = struct {
reexport: bool = false,
};

fn parseDylib(self: *MachO, arena: Allocator, obj: LinkObject, explicit: bool) anyerror!?File.Index {
fn parseDylib(self: *MachO, obj: LinkObject, explicit: bool) anyerror!?File.Index {
const tracy = trace(@src());
defer tracy.end();

Expand All @@ -809,42 +790,34 @@ fn parseDylib(self: *MachO, arena: Allocator, obj: LinkObject, explicit: bool) a
const file = try std.fs.cwd().openFile(obj.path, .{});
defer file.close();

var offset: u64 = 0;
var size: u64 = (try file.stat()).size;
if (fat.isFatLibrary(file)) {
const fat_arch = self.parseFatLibrary(obj.path, file) catch |err| switch (err) {
const fat_arch = if (fat.isFatLibrary(file)) blk: {
break :blk self.parseFatLibrary(obj.path, file) catch |err| switch (err) {
error.NoArchSpecified, error.MissingArch => return null,
else => |e| return e,
};
offset = fat_arch.offset;
size = fat_arch.size;
try file.seekTo(offset);
}
} else null;
const offset = if (fat_arch) |ar| ar.offset else 0;
try file.seekTo(offset);

const header = file.reader().readStruct(macho.mach_header_64) catch return null;
try file.seekTo(offset);

if (header.filetype != macho.MH_DYLIB) return null;

const data = try arena.alloc(u8, size);
const nread = try file.readAll(data);
if (nread != size) return error.InputOutput;

const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
self.files.set(index, .{ .dylib = .{
.path = obj.path,
.data = data,
.index = index,
.needed = obj.needed,
.weak = obj.weak,
.reexport = obj.reexport,
.explicit = explicit,
} });
const dylib = &self.files.items(.data)[index].dylib;
try dylib.parse(self);
try dylib.parse(self, file, fat_arch);

try self.dylibs.append(gpa, index);
self.validateCpuArch(index);
self.validateCpuArch(index, header.cputype);
self.validatePlatform(index);

return index;
Expand All @@ -871,7 +844,6 @@ fn parseTbd(self: *MachO, obj: LinkObject, explicit: bool) anyerror!?File.Index
const index = @as(File.Index, @intCast(try self.files.addOne(gpa)));
self.files.set(index, .{ .dylib = .{
.path = obj.path,
.data = &[0]u8{},
.index = index,
.needed = obj.needed,
.weak = obj.weak,
Expand Down Expand Up @@ -999,7 +971,7 @@ fn parseDependentDylibs(
.weak = is_weak,
};
const file_index = file_index: {
if (try self.parseDylib(arena, link_obj, false)) |file| break :file_index file;
if (try self.parseDylib(link_obj, false)) |file| break :file_index file;
if (try self.parseTbd(link_obj, false)) |file| break :file_index file;
break :file_index @as(File.Index, 0);
};
Expand Down Expand Up @@ -1057,6 +1029,8 @@ pub fn resolveSymbols(self: *MachO) !void {
const index = self.objects.items[i];
if (!self.getFile(index).?.object.alive) {
_ = self.objects.orderedRemove(i);
self.files.items(.data)[index].object.deinit(self.base.allocator);
self.files.set(index, .null);
} else i += 1;
}

Expand Down Expand Up @@ -1109,6 +1083,8 @@ fn deadStripDylibs(self: *MachO) void {
const index = self.dylibs.items[i];
if (!self.getFile(index).?.dylib.isAlive(self)) {
_ = self.dylibs.orderedRemove(i);
self.files.items(.data)[index].dylib.deinit(self.base.allocator);
self.files.set(index, .null);
} else i += 1;
}
}
Expand Down Expand Up @@ -1248,18 +1224,13 @@ fn createObjcSections(self: *MachO) !void {
}

for (objc_msgsend_syms.keys()) |sym_index| {
const internal = self.getInternalObject().?;
const sym = self.getSymbol(sym_index);
sym.value = 0;
sym.atom = 0;
sym.nlist_idx = 0;
sym.file = self.internal_object_index.?;
sym.flags = .{};
_ = try internal.addSymbol(sym.getName(self), self);
sym.visibility = .hidden;
const object = self.getInternalObject().?;
const name = eatPrefix(sym.getName(self), "_objc_msgSend$").?;
const selrefs_index = try object.addObjcMsgsendSections(name, self);
const selrefs_index = try internal.addObjcMsgsendSections(name, self);
try sym.addExtra(.{ .objc_selrefs = selrefs_index }, self);
try object.symbols.append(gpa, sym_index);
}
}

Expand Down Expand Up @@ -2145,6 +2116,7 @@ fn writeAtoms(self: *MachO) !void {
const atom = self.getAtom(atom_index).?;
assert(atom.flags.alive);
const off = atom.value - header.addr;
try atom.getCode(self, buffer[off..][0..atom.size]);
atom.resolveRelocs(self, buffer[off..][0..atom.size]) catch |err| switch (err) {
error.ResolveFailed => has_resolve_error = true,
else => |e| return e,
Expand Down Expand Up @@ -2892,6 +2864,7 @@ pub fn getOrCreateGlobal(self: *MachO, off: u32) !GetOrCreateGlobalResult {
if (!gop.found_existing) {
const index = try self.addSymbol();
const global = self.getSymbol(index);
global.flags.global = true;
global.name = off;
gop.value_ptr.* = index;
}
Expand Down
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