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compiler: Rework LTO settings for some Zig-provided libraries.

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* compiler-rt and mingw32 have both run into LLD bugs, and LLVM disables LTO for
  its compiler-rt, so disable LTO for these.
* While we haven't run into any bugs in it, LLVM disables LTO for its libtsan,
  so follow suit just to be safe.
* Allow LTO for libfuzzer as LLVM does.
This commit is contained in:
Alex Rønne Petersen 2025-01-25 14:47:14 +01:00
parent afe2fed34d
commit 1e8b82f6b4
No known key found for this signature in database
3 changed files with 19 additions and 4 deletions
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19
src/Compilation.zig
View File

@ -3695,15 +3695,19 @@ fn performAllTheWorkInner(
// In case it failed last time, try again. `clearMiscFailures` was already
// called at the start of `update`.
if (comp.queued_jobs.compiler_rt_lib and comp.compiler_rt_lib == null) {
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "compiler_rt.zig", .compiler_rt, .Lib, &comp.compiler_rt_lib, main_progress_node });
// LLVM disables LTO for its compiler-rt and we've had various issues with LTO of our
// compiler-rt due to LLD bugs as well, e.g.:
//
// https://github.com/llvm/llvm-project/issues/43698#issuecomment-2542660611
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "compiler_rt.zig", .compiler_rt, .Lib, false, &comp.compiler_rt_lib, main_progress_node });
}
if (comp.queued_jobs.compiler_rt_obj and comp.compiler_rt_obj == null) {
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "compiler_rt.zig", .compiler_rt, .Obj, &comp.compiler_rt_obj, main_progress_node });
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "compiler_rt.zig", .compiler_rt, .Obj, false, &comp.compiler_rt_obj, main_progress_node });
}
if (comp.queued_jobs.fuzzer_lib and comp.fuzzer_lib == null) {
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "fuzzer.zig", .libfuzzer, .Lib, &comp.fuzzer_lib, main_progress_node });
comp.link_task_wait_group.spawnManager(buildRt, .{ comp, "fuzzer.zig", .libfuzzer, .Lib, true, &comp.fuzzer_lib, main_progress_node });
}
if (comp.queued_jobs.glibc_shared_objects) {
@ -4635,12 +4639,14 @@ fn buildRt(
root_source_name: []const u8,
misc_task: MiscTask,
output_mode: std.builtin.OutputMode,
allow_lto: bool,
out: *?CrtFile,
prog_node: std.Progress.Node,
) void {
comp.buildOutputFromZig(
root_source_name,
output_mode,
allow_lto,
out,
misc_task,
prog_node,
@ -4748,6 +4754,7 @@ fn buildZigLibc(comp: *Compilation, prog_node: std.Progress.Node) void {
comp.buildOutputFromZig(
"c.zig",
.Lib,
true,
&comp.libc_static_lib,
.zig_libc,
prog_node,
@ -6453,6 +6460,7 @@ fn buildOutputFromZig(
comp: *Compilation,
src_basename: []const u8,
output_mode: std.builtin.OutputMode,
allow_lto: bool,
out: *?CrtFile,
misc_task_tag: MiscTask,
prog_node: std.Progress.Node,
@ -6481,6 +6489,7 @@ fn buildOutputFromZig(
.root_strip = strip,
.link_libc = comp.config.link_libc,
.any_unwind_tables = comp.root_mod.unwind_tables != .none,
.lto = if (allow_lto) comp.config.lto else .none,
});
const root_mod = try Package.Module.create(arena, .{
@ -6581,6 +6590,8 @@ pub const CrtFileOptions = struct {
unwind_tables: ?std.builtin.UnwindTables = null,
pic: ?bool = null,
no_builtin: ?bool = null,
allow_lto: bool = true,
};
pub fn build_crt_file(
@ -6619,7 +6630,7 @@ pub fn build_crt_file(
.link_libc = false,
.any_unwind_tables = options.unwind_tables != .none,
.lto = switch (output_mode) {
.Lib => comp.config.lto,
.Lib => if (options.allow_lto) comp.config.lto else .none,
.Obj, .Exe => .none,
},
});

2
src/libtsan.zig
View File

@ -65,6 +65,8 @@ pub fn buildTsan(comp: *Compilation, prog_node: std.Progress.Node) BuildError!vo
.root_strip = strip,
.link_libc = true,
.link_libcpp = link_libcpp,
// LLVM disables LTO for its libtsan.
.lto = .none,
}) catch |err| {
comp.setMiscFailure(
.libtsan,

2
src/mingw.zig
View File

@ -175,6 +175,8 @@ pub fn buildCrtFile(comp: *Compilation, crt_file: CrtFile, prog_node: std.Progre
return comp.build_crt_file("mingw32", .Lib, .@"mingw-w64 mingw32.lib", prog_node, c_source_files.items, .{
.unwind_tables = unwind_tables,
// https://github.com/llvm/llvm-project/issues/43698#issuecomment-2542660611
.allow_lto = false,
});
},
}