Commit b8c8565e93
src/link/Elf/file.zig
@@ -99,6 +99,21 @@ pub const File = union(enum) {
};
}
+ pub fn cies(file: File) []const Cie {
+ return switch (file) {
+ .zig_object => &[0]Cie{},
+ .object => |x| x.cies.items,
+ inline else => unreachable,
+ };
+ }
+
+ pub fn symbol(file: File, ind: Symbol.Index) Symbol.Index {
+ return switch (file) {
+ .zig_object => |x| x.symbol(ind),
+ inline else => |x| x.symbols.items[ind],
+ };
+ }
+
pub fn locals(file: File) []const Symbol.Index {
return switch (file) {
.linker_defined, .shared_object => &[0]Symbol.Index{},
@@ -196,6 +211,7 @@ const elf = std.elf;
const Allocator = std.mem.Allocator;
const Atom = @import("Atom.zig");
+const Cie = @import("eh_frame.zig").Cie;
const Elf = @import("../Elf.zig");
const LinkerDefined = @import("LinkerDefined.zig");
const Object = @import("Object.zig");
src/link/Elf/gc.zig
@@ -1,19 +1,27 @@
pub fn gcAtoms(elf_file: *Elf) !void {
- var roots = std.ArrayList(*Atom).init(elf_file.base.allocator);
+ const gpa = elf_file.base.allocator;
+ const num_files = elf_file.objects.items.len + @intFromBool(elf_file.zig_object_index != null);
+ var files = try std.ArrayList(File.Index).initCapacity(gpa, num_files);
+ defer files.deinit();
+ if (elf_file.zig_object_index) |index| files.appendAssumeCapacity(index);
+ for (elf_file.objects.items) |index| files.appendAssumeCapacity(index);
+
+ var roots = std.ArrayList(*Atom).init(gpa);
defer roots.deinit();
- try collectRoots(&roots, elf_file);
+ try collectRoots(&roots, files.items, elf_file);
+
mark(roots, elf_file);
- prune(elf_file);
+ prune(files.items, elf_file);
}
-fn collectRoots(roots: *std.ArrayList(*Atom), elf_file: *Elf) !void {
+fn collectRoots(roots: *std.ArrayList(*Atom), files: []const File.Index, elf_file: *Elf) !void {
if (elf_file.entry_index) |index| {
const global = elf_file.symbol(index);
try markSymbol(global, roots, elf_file);
}
- for (elf_file.objects.items) |index| {
- for (elf_file.file(index).?.object.globals()) |global_index| {
+ for (files) |index| {
+ for (elf_file.file(index).?.globals()) |global_index| {
const global = elf_file.symbol(global_index);
if (global.file(elf_file)) |file| {
if (file.index() == index and global.flags.@"export")
@@ -22,10 +30,10 @@ fn collectRoots(roots: *std.ArrayList(*Atom), elf_file: *Elf) !void {
}
}
- for (elf_file.objects.items) |index| {
- const object = elf_file.file(index).?.object;
+ for (files) |index| {
+ const file = elf_file.file(index).?;
- for (object.atoms.items) |atom_index| {
+ for (file.atoms()) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
if (!atom.flags.alive) continue;
@@ -49,9 +57,9 @@ fn collectRoots(roots: *std.ArrayList(*Atom), elf_file: *Elf) !void {
}
// Mark every atom referenced by CIE as alive.
- for (object.cies.items) |cie| {
+ for (file.cies()) |cie| {
for (cie.relocs(elf_file)) |rel| {
- const sym = elf_file.symbol(object.symbols.items[rel.r_sym()]);
+ const sym = elf_file.symbol(file.symbol(rel.r_sym()));
try markSymbol(sym, roots, elf_file);
}
}
@@ -73,11 +81,11 @@ fn markLive(atom: *Atom, elf_file: *Elf) void {
if (@import("build_options").enable_logging) track_live_level.incr();
assert(atom.flags.visited);
- const object = atom.file(elf_file).?.object;
+ const file = atom.file(elf_file).?;
for (atom.fdes(elf_file)) |fde| {
for (fde.relocs(elf_file)[1..]) |rel| {
- const target_sym = elf_file.symbol(object.symbols.items[rel.r_sym()]);
+ const target_sym = elf_file.symbol(file.symbol(rel.r_sym()));
const target_atom = target_sym.atom(elf_file) orelse continue;
target_atom.flags.alive = true;
gc_track_live_log.debug("{}marking live atom({d})", .{ track_live_level, target_atom.atom_index });
@@ -86,7 +94,7 @@ fn markLive(atom: *Atom, elf_file: *Elf) void {
}
for (atom.relocs(elf_file)) |rel| {
- const target_sym = elf_file.symbol(object.symbols.items[rel.r_sym()]);
+ const target_sym = elf_file.symbol(file.symbol(rel.r_sym()));
const target_atom = target_sym.atom(elf_file) orelse continue;
target_atom.flags.alive = true;
gc_track_live_log.debug("{}marking live atom({d})", .{ track_live_level, target_atom.atom_index });
@@ -101,9 +109,9 @@ fn mark(roots: std.ArrayList(*Atom), elf_file: *Elf) void {
}
}
-fn prune(elf_file: *Elf) void {
- for (elf_file.objects.items) |index| {
- for (elf_file.file(index).?.object.atoms.items) |atom_index| {
+fn prune(files: []const File.Index, elf_file: *Elf) void {
+ for (files) |index| {
+ for (elf_file.file(index).?.atoms()) |atom_index| {
const atom = elf_file.atom(atom_index) orelse continue;
if (atom.flags.alive and !atom.flags.visited) {
atom.flags.alive = false;
@@ -158,4 +166,5 @@ const mem = std.mem;
const Allocator = mem.Allocator;
const Atom = @import("Atom.zig");
const Elf = @import("../Elf.zig");
+const File = @import("file.zig").File;
const Symbol = @import("Symbol.zig");
test/link/elf.zig
@@ -6,9 +6,13 @@ pub fn build(b: *Build) void {
const elf_step = b.step("test-elf", "Run ELF tests");
b.default_step = elf_step;
- const musl_target = CrossTarget{
+ const default_target = CrossTarget{
.cpu_arch = .x86_64, // TODO relax this once ELF linker is able to handle other archs
.os_tag = .linux,
+ };
+ const musl_target = CrossTarget{
+ .cpu_arch = .x86_64,
+ .os_tag = .linux,
.abi = .musl,
};
const glibc_target = CrossTarget{
@@ -18,7 +22,8 @@ pub fn build(b: *Build) void {
};
// Exercise linker with self-hosted backend (no LLVM)
- elf_step.dependOn(testLinkingZig(b, .{ .use_llvm = false }));
+ elf_step.dependOn(testGcSectionsZig(b, .{ .use_llvm = false, .target = default_target }));
+ elf_step.dependOn(testLinkingZig(b, .{ .use_llvm = false, .target = default_target }));
elf_step.dependOn(testImportingDataDynamic(b, .{ .use_llvm = false, .target = glibc_target }));
elf_step.dependOn(testImportingDataStatic(b, .{ .use_llvm = false, .target = musl_target }));
@@ -876,6 +881,110 @@ fn testGcSections(b: *Build, opts: Options) *Step {
return test_step;
}
+fn testGcSectionsZig(b: *Build, opts: Options) *Step {
+ const test_step = addTestStep(b, "gc-sections-zig", opts);
+
+ const obj = addObject(b, "obj", .{
+ .target = opts.target,
+ .use_llvm = true,
+ .use_lld = true,
+ });
+ addCSourceBytes(obj,
+ \\int live_var1 = 1;
+ \\int live_var2 = 2;
+ \\int dead_var1 = 3;
+ \\int dead_var2 = 4;
+ \\void live_fn1() {}
+ \\void live_fn2() { live_fn1(); }
+ \\void dead_fn1() {}
+ \\void dead_fn2() { dead_fn1(); }
+ , &.{});
+ obj.link_function_sections = true;
+ obj.link_data_sections = true;
+
+ {
+ const exe = addExecutable(b, "test1", opts);
+ addZigSourceBytes(exe,
+ \\const std = @import("std");
+ \\extern var live_var1: i32;
+ \\extern var live_var2: i32;
+ \\extern fn live_fn2() void;
+ \\pub fn main() void {
+ \\ const stdout = std.io.getStdOut();
+ \\ stdout.writer().print("{d} {d}\n", .{ live_var1, live_var2 }) catch unreachable;
+ \\ live_fn2();
+ \\}
+ );
+ exe.addObject(obj);
+ exe.link_gc_sections = false;
+
+ const run = addRunArtifact(exe);
+ run.expectStdOutEqual("1 2\n");
+ test_step.dependOn(&run.step);
+
+ const check = exe.checkObject();
+ check.checkInSymtab();
+ check.checkContains("live_var1");
+ check.checkInSymtab();
+ check.checkContains("live_var2");
+ check.checkInSymtab();
+ check.checkContains("dead_var1");
+ check.checkInSymtab();
+ check.checkContains("dead_var2");
+ check.checkInSymtab();
+ check.checkContains("live_fn1");
+ check.checkInSymtab();
+ check.checkContains("live_fn2");
+ check.checkInSymtab();
+ check.checkContains("dead_fn1");
+ check.checkInSymtab();
+ check.checkContains("dead_fn2");
+ test_step.dependOn(&check.step);
+ }
+
+ {
+ const exe = addExecutable(b, "test2", opts);
+ addZigSourceBytes(exe,
+ \\const std = @import("std");
+ \\extern var live_var1: i32;
+ \\extern var live_var2: i32;
+ \\extern fn live_fn2() void;
+ \\pub fn main() void {
+ \\ const stdout = std.io.getStdOut();
+ \\ stdout.writer().print("{d} {d}\n", .{ live_var1, live_var2 }) catch unreachable;
+ \\ live_fn2();
+ \\}
+ );
+ exe.addObject(obj);
+ exe.link_gc_sections = true;
+
+ const run = addRunArtifact(exe);
+ run.expectStdOutEqual("1 2\n");
+ test_step.dependOn(&run.step);
+
+ const check = exe.checkObject();
+ check.checkInSymtab();
+ check.checkContains("live_var1");
+ check.checkInSymtab();
+ check.checkContains("live_var2");
+ check.checkInSymtab();
+ check.checkNotPresent("dead_var1");
+ check.checkInSymtab();
+ check.checkNotPresent("dead_var2");
+ check.checkInSymtab();
+ check.checkContains("live_fn1");
+ check.checkInSymtab();
+ check.checkContains("live_fn2");
+ check.checkInSymtab();
+ check.checkNotPresent("dead_fn1");
+ check.checkInSymtab();
+ check.checkNotPresent("dead_fn2");
+ test_step.dependOn(&check.step);
+ }
+
+ return test_step;
+}
+
fn testHiddenWeakUndef(b: *Build, opts: Options) *Step {
const test_step = addTestStep(b, "hidden-weak-undef", opts);
@@ -3114,6 +3223,7 @@ const Options = struct {
target: CrossTarget = .{ .cpu_arch = .x86_64, .os_tag = .linux },
optimize: std.builtin.OptimizeMode = .Debug,
use_llvm: bool = true,
+ use_lld: bool = false,
};
fn addTestStep(b: *Build, comptime prefix: []const u8, opts: Options) *Step {
@@ -3134,7 +3244,7 @@ fn addExecutable(b: *Build, name: []const u8, opts: Options) *Compile {
.target = opts.target,
.optimize = opts.optimize,
.use_llvm = opts.use_llvm,
- .use_lld = false,
+ .use_lld = opts.use_lld,
});
}
@@ -3144,7 +3254,7 @@ fn addObject(b: *Build, name: []const u8, opts: Options) *Compile {
.target = opts.target,
.optimize = opts.optimize,
.use_llvm = opts.use_llvm,
- .use_lld = false,
+ .use_lld = opts.use_lld,
});
}
@@ -3164,7 +3274,7 @@ fn addSharedLibrary(b: *Build, name: []const u8, opts: Options) *Compile {
.target = opts.target,
.optimize = opts.optimize,
.use_llvm = opts.use_llvm,
- .use_lld = false,
+ .use_lld = opts.use_lld,
});
}