stage2: rip out multi-compilation-unit compiler-rt

After doing performance testing, it seems that multi-compilation-unit
compiler-rt did not bring the performance improvements that we expected
it to. The idea is that it makes linking faster, however, it incurred a
cost in the frontend that was not offset by any gains in linking.

Furthermore, the single-object compiler-rt (with -ffunction-sections and
--gc-sections) ends up being fewer bytes on disk and so it's actually
the same or faster linking speed than the multi-compilation-unit
version.

So we are planning to keep using single-compilation-unit compiler-rt for
the foreseeable future, but may experiment with this again in the
future, in which case this commit can be reverted.

2 files changed, 10 insertions, 450 deletions

diff --git a/src/Compilation.zig b/src/Compilation.zig
index 89e54b598f..2646da2f6f 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -23,7 +23,6 @@ const mingw = @import("mingw.zig");
 const libunwind = @import("libunwind.zig");
 const libcxx = @import("libcxx.zig");
 const wasi_libc = @import("wasi_libc.zig");
-const compiler_rt = @import("compiler_rt.zig");
 const fatal = @import("main.zig").fatal;
 const clangMain = @import("main.zig").clangMain;
 const Module = @import("Module.zig");
@@ -2745,10 +2744,6 @@ pub fn performAllTheWork(
     var embed_file_prog_node = main_progress_node.start("Detect @embedFile updates", comp.embed_file_work_queue.count);
     defer embed_file_prog_node.end();
 
-    // +1 for the link step
-    var compiler_rt_prog_node = main_progress_node.start("compiler_rt", compiler_rt.sources.len + 1);
-    defer compiler_rt_prog_node.end();
-
     comp.work_queue_wait_group.reset();
     defer comp.work_queue_wait_group.wait();
 
@@ -2796,28 +2791,6 @@ pub fn performAllTheWork(
                 comp, c_object, &c_obj_prog_node, &comp.work_queue_wait_group,
             });
         }
-
-        if (comp.job_queued_compiler_rt_lib) {
-            comp.job_queued_compiler_rt_lib = false;
-
-            // I have disabled the multi-threaded compiler-rt for now until
-            // the threading deadlock is resolved.
-            if (use_stage1 or true) {
-                // stage1 LLVM backend uses the global context and thus cannot be used in
-                // a multi-threaded context.
-                buildCompilerRtOneShot(comp, .Lib, &comp.compiler_rt_lib);
-            } else {
-                comp.work_queue_wait_group.start();
-                try comp.thread_pool.spawn(workerBuildCompilerRtLib, .{
-                    comp, &compiler_rt_prog_node, &comp.work_queue_wait_group,
-                });
-            }
-        }
-
-        if (comp.job_queued_compiler_rt_obj) {
-            comp.job_queued_compiler_rt_obj = false;
-            buildCompilerRtOneShot(comp, .Obj, &comp.compiler_rt_obj);
-        }
     }
 
     if (!use_stage1) {
@@ -2862,6 +2835,16 @@ pub fn performAllTheWork(
         }
         break;
     }
+
+    if (comp.job_queued_compiler_rt_lib) {
+        comp.job_queued_compiler_rt_lib = false;
+        buildCompilerRtOneShot(comp, .Lib, &comp.compiler_rt_lib);
+    }
+
+    if (comp.job_queued_compiler_rt_obj) {
+        comp.job_queued_compiler_rt_obj = false;
+        buildCompilerRtOneShot(comp, .Obj, &comp.compiler_rt_obj);
+    }
 }
 
 fn processOneJob(comp: *Compilation, job: Job) !void {
@@ -3534,23 +3517,6 @@ fn buildCompilerRtOneShot(
     };
 }
 
-fn workerBuildCompilerRtLib(
-    comp: *Compilation,
-    progress_node: *std.Progress.Node,
-    wg: *WaitGroup,
-) void {
-    defer wg.finish();
-
-    compiler_rt.buildCompilerRtLib(comp, progress_node) catch |err| switch (err) {
-        error.SubCompilationFailed => return, // error reported already
-        else => comp.lockAndSetMiscFailure(
-            .compiler_rt,
-            "unable to build compiler_rt: {s}",
-            .{@errorName(err)},
-        ),
-    };
-}
-
 fn reportRetryableCObjectError(
     comp: *Compilation,
     c_object: *CObject,
diff --git a/src/compiler_rt.zig b/src/compiler_rt.zig
deleted file mode 100644
index 185ebf6b16..0000000000
--- a/src/compiler_rt.zig
+++ /dev/null
@@ -1,406 +0,0 @@
-const std = @import("std");
-const builtin = @import("builtin");
-const build_options = @import("build_options");
-const Allocator = std.mem.Allocator;
-const assert = std.debug.assert;
-const mem = std.mem;
-const tracy = @import("tracy.zig");
-const trace = tracy.trace;
-
-const Cache = @import("Cache.zig");
-const Compilation = @import("Compilation.zig");
-const CRTFile = Compilation.CRTFile;
-const LinkObject = Compilation.LinkObject;
-const Package = @import("Package.zig");
-const WaitGroup = @import("WaitGroup.zig");
-
-pub fn buildCompilerRtLib(comp: *Compilation, progress_node: *std.Progress.Node) !void {
-    var arena_allocator = std.heap.ArenaAllocator.init(comp.gpa);
-    defer arena_allocator.deinit();
-    const arena = arena_allocator.allocator();
-
-    const target = comp.getTarget();
-
-    const root_name = "compiler_rt";
-    const basename = try std.zig.binNameAlloc(arena, .{
-        .root_name = root_name,
-        .target = target,
-        .output_mode = .Lib,
-    });
-
-    var link_objects: [sources.len]LinkObject = undefined;
-    var crt_files = [1]?CRTFile{null} ** sources.len;
-    defer deinitCrtFiles(comp, crt_files);
-
-    {
-        var wg: WaitGroup = .{};
-        defer comp.thread_pool.waitAndWork(&wg);
-
-        for (sources) |source, i| {
-            wg.start();
-            try comp.thread_pool.spawn(workerBuildObject, .{
-                comp, progress_node, &wg, source, &crt_files[i],
-            });
-        }
-    }
-
-    for (link_objects) |*link_object, i| {
-        link_object.* = .{
-            .path = crt_files[i].?.full_object_path,
-        };
-    }
-
-    var link_progress_node = progress_node.start("link", 0);
-    link_progress_node.activate();
-    defer link_progress_node.end();
-
-    // TODO: This is extracted into a local variable to work around a stage1 miscompilation.
-    const emit_bin = Compilation.EmitLoc{
-        .directory = null, // Put it in the cache directory.
-        .basename = basename,
-    };
-    const sub_compilation = try Compilation.create(comp.gpa, .{
-        .local_cache_directory = comp.global_cache_directory,
-        .global_cache_directory = comp.global_cache_directory,
-        .zig_lib_directory = comp.zig_lib_directory,
-        .cache_mode = .whole,
-        .target = target,
-        .root_name = root_name,
-        .main_pkg = null,
-        .output_mode = .Lib,
-        .link_mode = .Static,
-        .function_sections = true,
-        .thread_pool = comp.thread_pool,
-        .libc_installation = comp.bin_file.options.libc_installation,
-        .emit_bin = emit_bin,
-        .optimize_mode = comp.compilerRtOptMode(),
-        .want_sanitize_c = false,
-        .want_stack_check = false,
-        .want_red_zone = comp.bin_file.options.red_zone,
-        .omit_frame_pointer = comp.bin_file.options.omit_frame_pointer,
-        .want_valgrind = false,
-        .want_tsan = false,
-        .want_pic = comp.bin_file.options.pic,
-        .want_pie = comp.bin_file.options.pie,
-        .want_lto = comp.bin_file.options.lto,
-        .emit_h = null,
-        .strip = comp.compilerRtStrip(),
-        .is_native_os = comp.bin_file.options.is_native_os,
-        .is_native_abi = comp.bin_file.options.is_native_abi,
-        .self_exe_path = comp.self_exe_path,
-        .link_objects = &link_objects,
-        .verbose_cc = comp.verbose_cc,
-        .verbose_link = comp.bin_file.options.verbose_link,
-        .verbose_air = comp.verbose_air,
-        .verbose_llvm_ir = comp.verbose_llvm_ir,
-        .verbose_cimport = comp.verbose_cimport,
-        .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
-        .clang_passthrough_mode = comp.clang_passthrough_mode,
-        .skip_linker_dependencies = true,
-        .parent_compilation_link_libc = comp.bin_file.options.link_libc,
-    });
-    defer sub_compilation.destroy();
-
-    try sub_compilation.updateSubCompilation();
-
-    assert(comp.compiler_rt_lib == null);
-    comp.compiler_rt_lib = .{
-        .full_object_path = try sub_compilation.bin_file.options.emit.?.directory.join(comp.gpa, &[_][]const u8{
-            sub_compilation.bin_file.options.emit.?.sub_path,
-        }),
-        .lock = sub_compilation.bin_file.toOwnedLock(),
-    };
-}
-
-fn deinitCrtFiles(comp: *Compilation, crt_files: [sources.len]?CRTFile) void {
-    const gpa = comp.gpa;
-
-    for (crt_files) |opt_crt_file| {
-        var crt_file = opt_crt_file orelse continue;
-        crt_file.deinit(gpa);
-    }
-}
-
-fn workerBuildObject(
-    comp: *Compilation,
-    progress_node: *std.Progress.Node,
-    wg: *WaitGroup,
-    src_basename: []const u8,
-    out: *?CRTFile,
-) void {
-    defer wg.finish();
-
-    var obj_progress_node = progress_node.start(src_basename, 0);
-    obj_progress_node.activate();
-    defer obj_progress_node.end();
-
-    buildObject(comp, src_basename, out) catch |err| switch (err) {
-        error.SubCompilationFailed => return, // error reported already
-        else => comp.lockAndSetMiscFailure(
-            .compiler_rt,
-            "unable to build compiler_rt: {s}",
-            .{@errorName(err)},
-        ),
-    };
-}
-
-fn buildObject(comp: *Compilation, src_basename: []const u8, out: *?CRTFile) !void {
-    const gpa = comp.gpa;
-
-    var root_src_path_buf: [64]u8 = undefined;
-    const root_src_path = std.fmt.bufPrint(
-        &root_src_path_buf,
-        "compiler_rt" ++ std.fs.path.sep_str ++ "{s}",
-        .{src_basename},
-    ) catch unreachable;
-
-    var main_pkg: Package = .{
-        .root_src_directory = comp.zig_lib_directory,
-        .root_src_path = root_src_path,
-    };
-    defer main_pkg.deinitTable(gpa);
-    const root_name = src_basename[0 .. src_basename.len - std.fs.path.extension(src_basename).len];
-    const target = comp.getTarget();
-    const output_mode: std.builtin.OutputMode = .Obj;
-    const bin_basename = try std.zig.binNameAlloc(gpa, .{
-        .root_name = root_name,
-        .target = target,
-        .output_mode = output_mode,
-    });
-    defer gpa.free(bin_basename);
-
-    const emit_bin = Compilation.EmitLoc{
-        .directory = null, // Put it in the cache directory.
-        .basename = bin_basename,
-    };
-    const sub_compilation = try Compilation.create(gpa, .{
-        .global_cache_directory = comp.global_cache_directory,
-        .local_cache_directory = comp.global_cache_directory,
-        .zig_lib_directory = comp.zig_lib_directory,
-        .cache_mode = .whole,
-        .target = target,
-        .root_name = root_name,
-        .main_pkg = &main_pkg,
-        .output_mode = output_mode,
-        .thread_pool = comp.thread_pool,
-        .libc_installation = comp.bin_file.options.libc_installation,
-        .emit_bin = emit_bin,
-        .optimize_mode = comp.compilerRtOptMode(),
-        .link_mode = .Static,
-        .function_sections = true,
-        .want_sanitize_c = false,
-        .want_stack_check = false,
-        .want_red_zone = comp.bin_file.options.red_zone,
-        .omit_frame_pointer = comp.bin_file.options.omit_frame_pointer,
-        .want_valgrind = false,
-        .want_tsan = false,
-        .want_pic = comp.bin_file.options.pic,
-        .want_pie = comp.bin_file.options.pie,
-        .emit_h = null,
-        .strip = comp.compilerRtStrip(),
-        .is_native_os = comp.bin_file.options.is_native_os,
-        .is_native_abi = comp.bin_file.options.is_native_abi,
-        .self_exe_path = comp.self_exe_path,
-        .verbose_cc = comp.verbose_cc,
-        .verbose_link = comp.bin_file.options.verbose_link,
-        .verbose_air = comp.verbose_air,
-        .verbose_llvm_ir = comp.verbose_llvm_ir,
-        .verbose_cimport = comp.verbose_cimport,
-        .verbose_llvm_cpu_features = comp.verbose_llvm_cpu_features,
-        .clang_passthrough_mode = comp.clang_passthrough_mode,
-        .skip_linker_dependencies = true,
-        .parent_compilation_link_libc = comp.bin_file.options.link_libc,
-    });
-    defer sub_compilation.destroy();
-
-    try sub_compilation.update();
-    // Look for compilation errors in this sub_compilation.
-    var keep_errors = false;
-    var errors = try sub_compilation.getAllErrorsAlloc();
-    defer if (!keep_errors) errors.deinit(sub_compilation.gpa);
-
-    if (errors.list.len != 0) {
-        const misc_task_tag: Compilation.MiscTask = .compiler_rt;
-
-        comp.mutex.lock();
-        defer comp.mutex.unlock();
-
-        try comp.misc_failures.ensureUnusedCapacity(gpa, 1);
-        comp.misc_failures.putAssumeCapacityNoClobber(misc_task_tag, .{
-            .msg = try std.fmt.allocPrint(gpa, "sub-compilation of {s} failed", .{
-                @tagName(misc_task_tag),
-            }),
-            .children = errors,
-        });
-        keep_errors = true;
-        return error.SubCompilationFailed;
-    }
-
-    assert(out.* == null);
-    out.* = Compilation.CRTFile{
-        .full_object_path = try sub_compilation.bin_file.options.emit.?.directory.join(gpa, &[_][]const u8{
-            sub_compilation.bin_file.options.emit.?.sub_path,
-        }),
-        .lock = sub_compilation.bin_file.toOwnedLock(),
-    };
-}
-
-pub const sources = &[_][]const u8{
-    "absvdi2.zig",
-    "absvsi2.zig",
-    "absvti2.zig",
-    "adddf3.zig",
-    "addo.zig",
-    "addsf3.zig",
-    "addtf3.zig",
-    "addxf3.zig",
-    "arm.zig",
-    "atomics.zig",
-    "aulldiv.zig",
-    "aullrem.zig",
-    "bswap.zig",
-    "ceil.zig",
-    "clear_cache.zig",
-    "cmp.zig",
-    "cmpdf2.zig",
-    "cmpsf2.zig",
-    "cmptf2.zig",
-    "cmpxf2.zig",
-    "cos.zig",
-    "count0bits.zig",
-    "divdf3.zig",
-    "divsf3.zig",
-    "divtf3.zig",
-    "divti3.zig",
-    "divxf3.zig",
-    "emutls.zig",
-    "exp.zig",
-    "exp2.zig",
-    "extenddftf2.zig",
-    "extenddfxf2.zig",
-    "extendhfsf2.zig",
-    "extendhftf2.zig",
-    "extendhfxf2.zig",
-    "extendsfdf2.zig",
-    "extendsftf2.zig",
-    "extendsfxf2.zig",
-    "extendxftf2.zig",
-    "fabs.zig",
-    "fixdfdi.zig",
-    "fixdfsi.zig",
-    "fixdfti.zig",
-    "fixhfdi.zig",
-    "fixhfsi.zig",
-    "fixhfti.zig",
-    "fixsfdi.zig",
-    "fixsfsi.zig",
-    "fixsfti.zig",
-    "fixtfdi.zig",
-    "fixtfsi.zig",
-    "fixtfti.zig",
-    "fixunsdfdi.zig",
-    "fixunsdfsi.zig",
-    "fixunsdfti.zig",
-    "fixunshfdi.zig",
-    "fixunshfsi.zig",
-    "fixunshfti.zig",
-    "fixunssfdi.zig",
-    "fixunssfsi.zig",
-    "fixunssfti.zig",
-    "fixunstfdi.zig",
-    "fixunstfsi.zig",
-    "fixunstfti.zig",
-    "fixunsxfdi.zig",
-    "fixunsxfsi.zig",
-    "fixunsxfti.zig",
-    "fixxfdi.zig",
-    "fixxfsi.zig",
-    "fixxfti.zig",
-    "floatdidf.zig",
-    "floatdihf.zig",
-    "floatdisf.zig",
-    "floatditf.zig",
-    "floatdixf.zig",
-    "floatsidf.zig",
-    "floatsihf.zig",
-    "floatsisf.zig",
-    "floatsitf.zig",
-    "floatsixf.zig",
-    "floattidf.zig",
-    "floattihf.zig",
-    "floattisf.zig",
-    "floattitf.zig",
-    "floattixf.zig",
-    "floatundidf.zig",
-    "floatundihf.zig",
-    "floatundisf.zig",
-    "floatunditf.zig",
-    "floatundixf.zig",
-    "floatunsidf.zig",
-    "floatunsihf.zig",
-    "floatunsisf.zig",
-    "floatunsitf.zig",
-    "floatunsixf.zig",
-    "floatuntidf.zig",
-    "floatuntihf.zig",
-    "floatuntisf.zig",
-    "floatuntitf.zig",
-    "floatuntixf.zig",
-    "floor.zig",
-    "fma.zig",
-    "fmax.zig",
-    "fmin.zig",
-    "fmod.zig",
-    "gedf2.zig",
-    "gesf2.zig",
-    "getf2.zig",
-    "gexf2.zig",
-    "int.zig",
-    "log.zig",
-    "log10.zig",
-    "log2.zig",
-    "modti3.zig",
-    "muldf3.zig",
-    "muldi3.zig",
-    "mulf3.zig",
-    "mulo.zig",
-    "mulsf3.zig",
-    "multf3.zig",
-    "multi3.zig",
-    "mulxf3.zig",
-    "negXf2.zig",
-    "negXi2.zig",
-    "negv.zig",
-    "os_version_check.zig",
-    "parity.zig",
-    "popcount.zig",
-    "round.zig",
-    "shift.zig",
-    "sin.zig",
-    "sincos.zig",
-    "sqrt.zig",
-    "stack_probe.zig",
-    "subdf3.zig",
-    "subo.zig",
-    "subsf3.zig",
-    "subtf3.zig",
-    "subxf3.zig",
-    "tan.zig",
-    "trunc.zig",
-    "truncdfhf2.zig",
-    "truncdfsf2.zig",
-    "truncsfhf2.zig",
-    "trunctfdf2.zig",
-    "trunctfhf2.zig",
-    "trunctfsf2.zig",
-    "trunctfxf2.zig",
-    "truncxfdf2.zig",
-    "truncxfhf2.zig",
-    "truncxfsf2.zig",
-    "udivmodti4.zig",
-    "udivti3.zig",
-    "umodti3.zig",
-    "unorddf2.zig",
-    "unordsf2.zig",
-    "unordtf2.zig",
-};