rework the bundle compiler-rt feature

 * it is now -fcompiler-rt and -fno-compiler-rt to override the (quite
   reasonable) default of bundling compiler-rt only for executables and
   dynamic libraries.
   - the build.zig API is still called bundle_compiler_rt however it is
     now an optional bool instead of a bool. leaving it as `null` means
     to use the compiler default.
 * renamed some internal identifiers to make the source more readable
 * additionally support -fcompiler-rt when doing build-obj for ELF files
   since that target already supports linking multiple objects into one.
   - includes an error message when attempting this for non-ELF. in the
     future this could additionally be supported with a more advanced
     implementation that does not rely on the linker.
 * properly populate the linker cache hash

5 files changed, 79 insertions, 56 deletions

diff --git a/lib/std/build.zig b/lib/std/build.zig
index 69af052e2a..c8439ca20a 100644
--- a/lib/std/build.zig
+++ b/lib/std/build.zig
@@ -1216,7 +1216,7 @@ pub const LibExeObjStep = struct {
     emit_bin: bool = true,
     emit_docs: bool = false,
     emit_h: bool = false,
-    bundle_compiler_rt: bool,
+    bundle_compiler_rt: ?bool = null,
     disable_stack_probing: bool,
     disable_sanitize_c: bool,
     rdynamic: bool,
@@ -1395,7 +1395,6 @@ pub const LibExeObjStep = struct {
             .exec_cmd_args = null,
             .name_prefix = "",
             .filter = null,
-            .bundle_compiler_rt = false,
             .disable_stack_probing = false,
             .disable_sanitize_c = false,
             .rdynamic = false,
@@ -2120,8 +2119,12 @@ pub const LibExeObjStep = struct {
         if (self.is_dynamic) {
             try zig_args.append("-dynamic");
         }
-        if (self.bundle_compiler_rt) {
-            try zig_args.append("--bundle-compiler-rt");
+        if (self.bundle_compiler_rt) |x| {
+            if (x) {
+                try zig_args.append("-fcompiler-rt");
+            } else {
+                try zig_args.append("-fno-compiler-rt");
+            }
         }
         if (self.disable_stack_probing) {
             try zig_args.append("-fno-stack-check");
diff --git a/src/Compilation.zig b/src/Compilation.zig
index fe67cf31b7..b7660718de 100644
--- a/src/Compilation.zig
+++ b/src/Compilation.zig
@@ -167,9 +167,7 @@ const Job = union(enum) {
     libcxx: void,
     libcxxabi: void,
     libssp: void,
-    /// needed when producing a dynamic library or executable
-    libcompiler_rt: void,
-    /// needed when producing a static library with bundle-compiler-rt
+    compiler_rt_lib: void,
     compiler_rt_obj: void,
     /// needed when not linking libc and using LLVM for code generation because it generates
     /// calls to, for example, memcpy and memset.
@@ -355,6 +353,7 @@ pub const InitOptions = struct {
     want_sanitize_c: ?bool = null,
     want_stack_check: ?bool = null,
     want_valgrind: ?bool = null,
+    want_compiler_rt: ?bool = null,
     use_llvm: ?bool = null,
     use_lld: ?bool = null,
     use_clang: ?bool = null,
@@ -392,7 +391,6 @@ pub const InitOptions = struct {
     parent_compilation_link_libc: bool = false,
     stack_size_override: ?u64 = null,
     image_base_override: ?u64 = null,
-    bundle_compiler_rt: bool = false,
     self_exe_path: ?[]const u8 = null,
     version: ?std.builtin.Version = null,
     libc_installation: ?*const LibCInstallation = null,
@@ -410,15 +408,14 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
         .Obj, .Exe => false,
         .Lib => (options.link_mode orelse .Static) == .Dynamic,
     };
-    const is_static_lib = switch (options.output_mode) {
-        .Obj, .Exe => false,
-        .Lib => (options.link_mode orelse .Static) == .Static,
-    };
     const is_exe_or_dyn_lib = switch (options.output_mode) {
         .Obj => false,
         .Lib => is_dyn_lib,
         .Exe => true,
     };
+    const needs_c_symbols = !options.is_compiler_rt_or_libc and
+        (is_exe_or_dyn_lib or (options.target.isWasm() and options.output_mode != .Obj));
+
     const comp: *Compilation = comp: {
         // For allocations that have the same lifetime as Compilation. This arena is used only during this
         // initialization and then is freed in deinit().
@@ -595,6 +592,8 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             break :b options.want_valgrind orelse (options.optimize_mode == .Debug);
         };
 
+        const include_compiler_rt = options.want_compiler_rt orelse needs_c_symbols;
+
         const single_threaded = options.single_threaded or target_util.isSingleThreaded(options.target);
 
         const llvm_cpu_features: ?[*:0]const u8 = if (build_options.have_llvm and use_llvm) blk: {
@@ -831,7 +830,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .z_defs = options.linker_z_defs,
             .stack_size_override = options.stack_size_override,
             .image_base_override = options.image_base_override,
-            .bundle_compiler_rt = options.bundle_compiler_rt,
+            .include_compiler_rt = include_compiler_rt,
             .linker_script = options.linker_script,
             .version_script = options.version_script,
             .gc_sections = options.linker_gc_sections,
@@ -978,24 +977,31 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             try comp.work_queue.writeItem(.libcxxabi);
         }
 
-        const needs_libc = is_exe_or_dyn_lib or
-            (comp.getTarget().isWasm() and comp.bin_file.options.output_mode != .Obj);
-        const needs_compiler_rt = options.bundle_compiler_rt or needs_libc;
-
-        if (needs_compiler_rt and build_options.is_stage1) {
-            if (is_static_lib) {
-                try comp.work_queue.writeItem(.{ .compiler_rt_obj = {} });
-            } else {
-                try comp.work_queue.writeItem(.{ .libcompiler_rt = {} });
-            }
-        }
-        if (needs_libc and build_options.is_stage1) {
-            // MinGW provides no libssp, use our own implementation.
-            if (comp.getTarget().isMinGW()) {
-                try comp.work_queue.writeItem(.{ .libssp = {} });
+        // The `is_stage1` condition is here only because stage2 cannot yet build compiler-rt.
+        // Once it is capable this condition should be removed.
+        if (build_options.is_stage1) {
+            if (comp.bin_file.options.include_compiler_rt) {
+                if (is_exe_or_dyn_lib) {
+                    try comp.work_queue.writeItem(.{ .compiler_rt_lib = {} });
+                } else {
+                    try comp.work_queue.writeItem(.{ .compiler_rt_obj = {} });
+                    if (comp.bin_file.options.object_format != .elf) {
+                        // For ELF we can rely on using -r to link multiple objects together into one,
+                        // but to truly support `build-obj -fcompiler-rt` will require virtually
+                        // injecting `_ = @import("compiler_rt.zig")` into the root source file of
+                        // the compilation.
+                        fatal("Embedding compiler-rt into non-ELF objects is not yet implemented.", .{});
+                    }
+                }
             }
-            if (!comp.bin_file.options.link_libc) {
-                try comp.work_queue.writeItem(.{ .zig_libc = {} });
+            if (needs_c_symbols) {
+                // MinGW provides no libssp, use our own implementation.
+                if (comp.getTarget().isMinGW()) {
+                    try comp.work_queue.writeItem(.{ .libssp = {} });
+                }
+                if (!comp.bin_file.options.link_libc) {
+                    try comp.work_queue.writeItem(.{ .zig_libc = {} });
+                }
             }
         }
     }
@@ -1393,26 +1399,26 @@ pub fn performAllTheWork(self: *Compilation) error{ TimerUnsupported, OutOfMemor
                 fatal("unable to build libcxxabi: {}", .{@errorName(err)});
             };
         },
-        .libcompiler_rt => {
-            self.buildStaticLibFromZig("compiler_rt.zig", &self.compiler_rt_static_lib) catch |err| {
+        .compiler_rt_lib => {
+            self.buildOutputFromZig("compiler_rt.zig", .Lib, &self.compiler_rt_static_lib) catch |err| {
                 // TODO Expose this as a normal compile error rather than crashing here.
-                fatal("unable to build compiler_rt: {}", .{@errorName(err)});
+                fatal("unable to build compiler_rt: {s}", .{@errorName(err)});
             };
         },
         .compiler_rt_obj => {
             self.buildOutputFromZig("compiler_rt.zig", .Obj, &self.compiler_rt_obj) catch |err| {
                 // TODO Expose this as a normal compile error rather than crashing here.
-                fatal("unable to build compiler_rt: {}", .{@errorName(err)});
+                fatal("unable to build compiler_rt: {s}", .{@errorName(err)});
             };
         },
         .libssp => {
-            self.buildStaticLibFromZig("ssp.zig", &self.libssp_static_lib) catch |err| {
+            self.buildOutputFromZig("ssp.zig", .Lib, &self.libssp_static_lib) catch |err| {
                 // TODO Expose this as a normal compile error rather than crashing here.
                 fatal("unable to build libssp: {}", .{@errorName(err)});
             };
         },
         .zig_libc => {
-            self.buildStaticLibFromZig("c.zig", &self.libc_static_lib) catch |err| {
+            self.buildOutputFromZig("c.zig", .Lib, &self.libc_static_lib) catch |err| {
                 // TODO Expose this as a normal compile error rather than crashing here.
                 fatal("unable to build zig's multitarget libc: {}", .{@errorName(err)});
             };
@@ -2670,10 +2676,6 @@ fn buildOutputFromZig(
     };
 }
 
-fn buildStaticLibFromZig(comp: *Compilation, src_basename: []const u8, out: *?CRTFile) !void {
-    return buildOutputFromZig(comp, src_basename, .Lib, out);
-}
-
 fn updateStage1Module(comp: *Compilation, main_progress_node: *std.Progress.Node) !void {
     const tracy = trace(@src());
     defer tracy.end();
diff --git a/src/link.zig b/src/link.zig
index c24c003073..3df3727fc3 100644
--- a/src/link.zig
+++ b/src/link.zig
@@ -46,7 +46,7 @@ pub const Options = struct {
     entry_addr: ?u64 = null,
     stack_size_override: ?u64,
     image_base_override: ?u64,
-    bundle_compiler_rt: bool,
+    include_compiler_rt: bool,
     /// Set to `true` to omit debug info.
     strip: bool,
     /// If this is true then this link code is responsible for outputting an object
@@ -474,6 +474,11 @@ pub const File = struct {
             break :blk full_obj_path;
         } else null;
 
+        const compiler_rt_path: ?[]const u8 = if (base.options.include_compiler_rt)
+            comp.compiler_rt_obj.?.full_object_path
+        else
+            null;
+
         // This function follows the same pattern as link.Elf.linkWithLLD so if you want some
         // insight as to what's going on here you can read that function body which is more
         // well-commented.
@@ -490,6 +495,7 @@ pub const File = struct {
             _ = try ch.addFile(entry.key.status.success.object_path, null);
         }
         try ch.addOptionalFile(module_obj_path);
+        try ch.addOptionalFile(compiler_rt_path);
 
         // We don't actually care whether it's a cache hit or miss; we just need the digest and the lock.
         _ = try ch.hit();
@@ -519,8 +525,7 @@ pub const File = struct {
         var object_files = std.ArrayList([*:0]const u8).init(base.allocator);
         defer object_files.deinit();
 
-        try object_files.ensureCapacity(base.options.objects.len + comp.c_object_table.items().len +
-            1 + @boolToInt(base.options.bundle_compiler_rt));
+        try object_files.ensureCapacity(base.options.objects.len + comp.c_object_table.items().len + 2);
         for (base.options.objects) |obj_path| {
             object_files.appendAssumeCapacity(try arena.dupeZ(u8, obj_path));
         }
@@ -530,8 +535,8 @@ pub const File = struct {
         if (module_obj_path) |p| {
             object_files.appendAssumeCapacity(try arena.dupeZ(u8, p));
         }
-        if (base.options.bundle_compiler_rt) {
-            object_files.appendAssumeCapacity(try arena.dupeZ(u8, comp.compiler_rt_obj.?.full_object_path));
+        if (compiler_rt_path) |p| {
+            object_files.appendAssumeCapacity(try arena.dupeZ(u8, p));
         }
 
         const full_out_path = try directory.join(arena, &[_][]const u8{base.options.emit.?.sub_path});
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index 82c3df35ea..66542027e1 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -1260,6 +1260,13 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
     const gc_sections = self.base.options.gc_sections orelse !is_obj;
     const stack_size = self.base.options.stack_size_override orelse 16777216;
     const allow_shlib_undefined = self.base.options.allow_shlib_undefined orelse !self.base.options.is_native_os;
+    const compiler_rt_path: ?[]const u8 = if (self.base.options.include_compiler_rt) blk: {
+        if (is_exe_or_dyn_lib) {
+            break :blk comp.compiler_rt_static_lib.?.full_object_path;
+        } else {
+            break :blk comp.compiler_rt_obj.?.full_object_path;
+        }
+    } else null;
 
     // Here we want to determine whether we can save time by not invoking LLD when the
     // output is unchanged. None of the linker options or the object files that are being
@@ -1289,6 +1296,8 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
             _ = try man.addFile(entry.key.status.success.object_path, null);
         }
         try man.addOptionalFile(module_obj_path);
+        try man.addOptionalFile(compiler_rt_path);
+
         // We can skip hashing libc and libc++ components that we are in charge of building from Zig
         // installation sources because they are always a product of the compiler version + target information.
         man.hash.add(stack_size);
@@ -1531,12 +1540,14 @@ fn linkWithLLD(self: *Elf, comp: *Compilation) !void {
         try argv.append(p);
     }
 
-    // compiler-rt and libc
-    if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc) {
-        if (!self.base.options.link_libc) {
-            try argv.append(comp.libc_static_lib.?.full_object_path);
-        }
-        try argv.append(comp.compiler_rt_static_lib.?.full_object_path);
+    // libc
+    if (is_exe_or_dyn_lib and !self.base.options.is_compiler_rt_or_libc and !self.base.options.link_libc) {
+        try argv.append(comp.libc_static_lib.?.full_object_path);
+    }
+
+    // compiler-rt
+    if (compiler_rt_path) |p| {
+        try argv.append(p);
     }
 
     // Shared libraries.
diff --git a/src/main.zig b/src/main.zig
index 76e49cde2e..5e406152d3 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -314,7 +314,7 @@ const usage_build_generic =
     \\  -fno-soname                    (Linux) Disable emitting a SONAME
     \\  -fLLD                          Force using LLD as the linker
     \\  -fno-LLD                       Prevent using LLD as the linker
-    \\  -fcompiler-rt                  Always including compiler-rt symbols in output
+    \\  -fcompiler-rt                  Always include compiler-rt symbols in output
     \\  -fno-compiler-rt               Prevent including compiler-rt symbols in output
     \\  -rdynamic                      Add all symbols to the dynamic symbol table
     \\  -rpath [path]                  Add directory to the runtime library search path
@@ -480,6 +480,7 @@ fn buildOutputType(
     var want_sanitize_c: ?bool = null;
     var want_stack_check: ?bool = null;
     var want_valgrind: ?bool = null;
+    var want_compiler_rt: ?bool = null;
     var rdynamic: bool = false;
     var linker_script: ?[]const u8 = null;
     var version_script: ?[]const u8 = null;
@@ -492,7 +493,6 @@ fn buildOutputType(
     var test_evented_io = false;
     var stack_size_override: ?u64 = null;
     var image_base_override: ?u64 = null;
-    var bundle_compiler_rt = false;
     var use_llvm: ?bool = null;
     var use_lld: ?bool = null;
     var use_clang: ?bool = null;
@@ -797,8 +797,10 @@ fn buildOutputType(
                         if (i + 1 >= args.len) fatal("expected parameter after {}", .{arg});
                         i += 1;
                         override_lib_dir = args[i];
-                    } else if (mem.eql(u8, arg, "--bundle-compiler-rt")) {
-                        bundle_compiler_rt = true;
+                    } else if (mem.eql(u8, arg, "-fcompiler-rt")) {
+                        want_compiler_rt = true;
+                    } else if (mem.eql(u8, arg, "-fno-compiler-rt")) {
+                        want_compiler_rt = false;
                     } else if (mem.eql(u8, arg, "-feach-lib-rpath")) {
                         each_lib_rpath = true;
                     } else if (mem.eql(u8, arg, "-fno-each-lib-rpath")) {
@@ -1693,6 +1695,7 @@ fn buildOutputType(
         .want_sanitize_c = want_sanitize_c,
         .want_stack_check = want_stack_check,
         .want_valgrind = want_valgrind,
+        .want_compiler_rt = want_compiler_rt,
         .use_llvm = use_llvm,
         .use_lld = use_lld,
         .use_clang = use_clang,
@@ -1710,7 +1713,6 @@ fn buildOutputType(
         .link_emit_relocs = link_emit_relocs,
         .stack_size_override = stack_size_override,
         .image_base_override = image_base_override,
-        .bundle_compiler_rt = bundle_compiler_rt,
         .strip = strip,
         .single_threaded = single_threaded,
         .function_sections = function_sections,