review: exec-model non-optional in link option, style improvements.

also drop the support for the old crt1.o in favor of crt1-command.o

Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>

lib/std/start.zig

@@ -16,7 +16,7 @@ const native_os = builtin.os.tag;
 
 var argc_argv_ptr: [*]usize = undefined;
 
-const start_sym_name = if (native_arch.isMIPS()) "__start" else if (builtin.wasi_exec_model == .reactor) "_initialize" else "_start";
+const start_sym_name = if (native_arch.isMIPS()) "__start" else "_start";
 
 comptime {
     // No matter what, we import the root file, so that any export, test, comptime
@@ -65,7 +65,8 @@ comptime {
             } else if (native_os == .uefi) {
                 if (!@hasDecl(root, "EfiMain")) @export(EfiMain, .{ .name = "EfiMain" });
             } else if (native_arch.isWasm()) {
-                if (!@hasDecl(root, start_sym_name)) @export(wasm_start, .{ .name = start_sym_name });
+                const wasm_start_sym = if (builtin.wasi_exec_model == .reactor) "_initialize" else "_start";
+                if (!@hasDecl(root, start_sym_name)) @export(wasm_start, .{ .name = wasm_start_sym });
             } else if (native_os != .other and native_os != .freestanding) {
                 if (!@hasDecl(root, start_sym_name)) @export(_start, .{ .name = start_sym_name });
             }

src/Compilation.zig

@@ -787,6 +787,9 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
 
     const needs_c_symbols = !options.skip_linker_dependencies and is_exe_or_dyn_lib;
 
+    // WASI-only. Resolve the optinal exec-model option, defaults to command.
+    const wasi_exec_model = if (options.target.os.tag != .wasi) undefined else options.wasi_exec_model orelse .command;
+
     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().
@@ -1344,7 +1347,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .disable_lld_caching = options.disable_lld_caching,
             .subsystem = options.subsystem,
             .is_test = options.is_test,
-            .wasi_exec_model = options.wasi_exec_model,
+            .wasi_exec_model = wasi_exec_model,
         });
         errdefer bin_file.destroy();
         comp.* = .{
@@ -1446,7 +1449,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
                 });
             }
             comp.work_queue.writeAssumeCapacity(&[_]Job{
-                .{ .wasi_libc_crt_file = wasi_libc.getExecModelCRTFIle(options.wasi_exec_model) },
+                .{ .wasi_libc_crt_file = wasi_libc.getExecModelCrtFIle(wasi_exec_model) },
                 .{ .wasi_libc_crt_file = .libc_a },
             });
         }
@@ -3638,14 +3641,13 @@ pub fn generateBuiltinZigSource(comp: *Compilation, allocator: *Allocator) Alloc
         std.zig.fmtId(@tagName(comp.bin_file.options.machine_code_model)),
     });
 
-    const wasi_exec_model_fmt = if (comp.bin_file.options.wasi_exec_model) |model|
-        std.zig.fmtId(@tagName(model))
-    else
-        std.zig.fmtId(@tagName(std.builtin.WasiExecModel.command));
-    try buffer.writer().print(
-        \\pub const wasi_exec_model = std.builtin.WasiExecModel.{};
-        \\
-    , .{wasi_exec_model_fmt});
+    if (comp.getTarget().os.tag == .wasi) {
+        const wasi_exec_model_fmt = std.zig.fmtId(@tagName(comp.bin_file.options.wasi_exec_model));
+        try buffer.writer().print(
+            \\pub const wasi_exec_model = std.builtin.WasiExecModel.{};
+            \\
+        , .{wasi_exec_model_fmt});
+    }
 
     if (comp.bin_file.options.is_test) {
         try buffer.appendSlice(

src/link.zig

@@ -119,7 +119,7 @@ pub const Options = struct {
     libc_installation: ?*const LibCInstallation,
 
     /// WASI-only. Type of WASI execution model ("command" or "reactor").
-    wasi_exec_model: ?std.builtin.WasiExecModel,
+    wasi_exec_model: std.builtin.WasiExecModel = undefined,
 
     pub fn effectiveOutputMode(options: Options) std.builtin.OutputMode {
         return if (options.use_lld) .Obj else options.output_mode;

src/link/Wasm.zig

@@ -682,8 +682,7 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
             // before corrupting globals. See https://github.com/ziglang/zig/issues/4496
             try argv.append("--stack-first");
 
-            if (self.base.options.wasi_exec_model) |exec_model| blk: {
-                if (exec_model != .reactor) break :blk;
+            if (self.base.options.wasi_exec_model == .reactor) {
                 // Reactor execution model does not have _start so lld doesn't look for it.
                 try argv.append("--no-entry");
                 // Make sure "_initialize" is exported even if this is pure Zig WASI reactor
@@ -718,7 +717,7 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
                 if (self.base.options.link_libc) {
                     try argv.append(try comp.get_libc_crt_file(
                         arena,
-                        wasi_libc.execModelCRTFileFullName(self.base.options.wasi_exec_model),
+                        wasi_libc.execModelCrtFileFullName(self.base.options.wasi_exec_model),
                     ));
                     try argv.append(try comp.get_libc_crt_file(arena, "libc.a"));
                 }

src/main.zig

@@ -1067,12 +1067,9 @@ fn buildOutputType(
                     {
                         try clang_argv.append(arg);
                     } else if (mem.startsWith(u8, arg, "-mexec-model=")) {
-                        const value = arg["-mexec-model=".len..];
-                        if (std.mem.eql(u8, value, "reactor")) {
-                            wasi_exec_model = .reactor;
-                        } else if (std.mem.eql(u8, value, "command")) {
-                            wasi_exec_model = .command;
-                        }
+                        wasi_exec_model = std.meta.stringToEnum(std.builtin.WasiExecModel, arg["-mexec-model=".len..]) orelse {
+                            fatal("expected [command|reactor] for -mexec-mode=[value], found '{s}'", .{arg["-mexec-model=".len..]});
+                        };
                     } else {
                         fatal("unrecognized parameter: '{s}'", .{arg});
                     }
@@ -1279,11 +1276,9 @@ fn buildOutputType(
                     .nostdlibinc => want_native_include_dirs = false,
                     .strip => strip = true,
                     .exec_model => {
-                        if (std.mem.eql(u8, it.only_arg, "reactor")) {
-                            wasi_exec_model = .reactor;
-                        } else if (std.mem.eql(u8, it.only_arg, "command")) {
-                            wasi_exec_model = .command;
-                        }
+                        wasi_exec_model = std.meta.stringToEnum(std.builtin.WasiExecModel, it.only_arg) orelse {
+                            fatal("expected [command|reactor] for -mexec-mode=[value], found '{s}'", .{it.only_arg});
+                        };
                     },
                 }
             }

src/wasi_libc.zig

@@ -45,19 +45,15 @@ pub fn emulatedLibCRFileLibName(crt_file: CRTFile) []const u8 {
     };
 }
 
-pub fn getExecModelCRTFIle(wasi_exec_model: ?std.builtin.WasiExecModel) CRTFile {
-    return if (wasi_exec_model) |model|
-        switch (model) {
-            .reactor => CRTFile.crt1_reactor_o,
-            .command => CRTFile.crt1_command_o,
-        }
-    else
-        CRTFile.crt1_o;
+pub fn getExecModelCrtFIle(wasi_exec_model: std.builtin.WasiExecModel) CRTFile {
+    return switch (wasi_exec_model) {
+        .reactor => CRTFile.crt1_reactor_o,
+        .command => CRTFile.crt1_command_o,
+    };
 }
 
-pub fn execModelCRTFileFullName(wasi_exec_model: ?std.builtin.WasiExecModel) []const u8 {
-    return switch (getExecModelCRTFIle(wasi_exec_model)) {
-        .crt1_o => "crt1.o",
+pub fn execModelCrtFileFullName(wasi_exec_model: std.builtin.WasiExecModel) []const u8 {
+    return switch (getExecModelCrtFIle(wasi_exec_model)) {
         .crt1_reactor_o => "crt1-reactor.o",
         .crt1_command_o => "crt1-command.o",
         else => unreachable,