cc,wasi: include emulated libs in WASI libc and refactor WASI libc handling

src/Compilation.zig

@@ -203,8 +203,8 @@ const Job = union(enum) {
     /// needed when not linking libc and using LLVM for code generation because it generates
     /// calls to, for example, memcpy and memset.
     zig_libc: void,
-    /// WASI libc sysroot
-    wasi_libc_sysroot: void,
+    /// one of WASI libc static objects
+    wasi_libc_crt_file: wasi_libc.CRTFile,
 
     /// Use stage1 C++ code to compile zig code into an object file.
     stage1_module: void,
@@ -279,7 +279,7 @@ pub const MiscTask = enum {
     libcxx,
     libcxxabi,
     libtsan,
-    wasi_libc_sysroot,
+    wasi_libc_crt_file,
     compiler_rt,
     libssp,
     zig_libc,
@@ -646,6 +646,12 @@ pub const InitOptions = struct {
     framework_dirs: []const []const u8 = &[0][]const u8{},
     frameworks: []const []const u8 = &[0][]const u8{},
     system_libs: []const []const u8 = &[0][]const u8{},
+    /// These correspond to the WASI libc emulated subcomponents including:
+    /// * process clocks
+    /// * getpid
+    /// * mman
+    /// * signal
+    wasi_emulated_libs: []const wasi_libc.CRTFile = &[0]wasi_libc.CRTFile{},
     link_libc: bool = false,
     link_libcpp: bool = false,
     link_libunwind: bool = false,
@@ -1286,6 +1292,7 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
             .framework_dirs = options.framework_dirs,
             .system_libs = system_libs,
             .syslibroot = darwin_options.syslibroot,
+            .wasi_emulated_libs = options.wasi_emulated_libs,
             .lib_dirs = options.lib_dirs,
             .rpath_list = options.rpath_list,
             .strip = strip,
@@ -1426,8 +1433,19 @@ pub fn create(gpa: *Allocator, options: InitOptions) !*Compilation {
                 },
             });
         }
-        if (comp.wantBuildWasiLibcSysrootFromSource()) {
-            try comp.work_queue.write(&[_]Job{.{ .wasi_libc_sysroot = {} }});
+        if (comp.wantBuildWasiLibcFromSource()) {
+            const wasi_emulated_libs = comp.bin_file.options.wasi_emulated_libs;
+            try comp.work_queue.ensureUnusedCapacity(wasi_emulated_libs.len + 2); // worst-case we need all components
+            for (wasi_emulated_libs) |crt_file| {
+                comp.work_queue.writeItemAssumeCapacity(.{
+                    .wasi_libc_crt_file = crt_file,
+                });
+            }
+            // TODO add logic deciding which crt1 we want here.
+            comp.work_queue.writeAssumeCapacity(&[_]Job{
+                .{ .wasi_libc_crt_file = .crt1_o },
+                .{ .wasi_libc_crt_file = .libc_a },
+            });
         }
         if (comp.wantBuildMinGWFromSource()) {
             const static_lib_jobs = [_]Job{
@@ -2169,12 +2187,12 @@ pub fn performAllTheWork(self: *Compilation) error{ TimerUnsupported, OutOfMemor
                 );
             };
         },
-        .wasi_libc_sysroot => {
-            wasi_libc.buildWasiLibcSysroot(self) catch |err| {
+        .wasi_libc_crt_file => |crt_file| {
+            wasi_libc.buildCRTFile(self, crt_file) catch |err| {
                 // TODO Surface more error details.
                 try self.setMiscFailure(
-                    .wasi_libc_sysroot,
-                    "unable to build WASI libc sysroot: {s}",
+                    .wasi_libc_crt_file,
+                    "unable to build WASI libc CRT file: {s}",
                     .{@errorName(err)},
                 );
             };
@@ -3303,7 +3321,7 @@ pub fn get_libc_crt_file(comp: *Compilation, arena: *Allocator, basename: []cons
     if (comp.wantBuildGLibCFromSource() or
         comp.wantBuildMuslFromSource() or
         comp.wantBuildMinGWFromSource() or
-        comp.wantBuildWasiLibcSysrootFromSource())
+        comp.wantBuildWasiLibcFromSource())
     {
         return comp.crt_files.get(basename).?.full_object_path;
     }
@@ -3343,8 +3361,9 @@ fn wantBuildMuslFromSource(comp: Compilation) bool {
         !comp.getTarget().isWasm();
 }
 
-fn wantBuildWasiLibcSysrootFromSource(comp: Compilation) bool {
-    return comp.wantBuildLibCFromSource() and comp.getTarget().isWasm();
+fn wantBuildWasiLibcFromSource(comp: Compilation) bool {
+    return comp.wantBuildLibCFromSource() and comp.getTarget().isWasm() and
+        comp.getTarget().os.tag == .wasi;
 }
 
 fn wantBuildMinGWFromSource(comp: Compilation) bool {

src/link.zig

@@ -13,6 +13,7 @@ const Type = @import("type.zig").Type;
 const Cache = @import("Cache.zig");
 const build_options = @import("build_options");
 const LibCInstallation = @import("libc_installation.zig").LibCInstallation;
+const wasi_libc = @import("wasi_libc.zig");
 
 pub const producer_string = if (std.builtin.is_test) "zig test" else "zig " ++ build_options.version;
 
@@ -110,6 +111,7 @@ pub const Options = struct {
     framework_dirs: []const []const u8,
     frameworks: []const []const u8,
     system_libs: std.StringArrayHashMapUnmanaged(void),
+    wasi_emulated_libs: []const wasi_libc.CRTFile,
     lib_dirs: []const []const u8,
     rpath_list: []const []const u8,
 

src/link/Wasm.zig

@@ -15,6 +15,7 @@ const codegen = @import("../codegen/wasm.zig");
 const link = @import("../link.zig");
 const trace = @import("../tracy.zig").trace;
 const build_options = @import("build_options");
+const wasi_libc = @import("../wasi_libc.zig");
 const Cache = @import("../Cache.zig");
 const TypedValue = @import("../TypedValue.zig");
 
@@ -574,7 +575,6 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
         null;
 
     const target = self.base.options.target;
-    const link_in_crt = self.base.options.link_libc and self.base.options.output_mode == .Exe;
 
     const id_symlink_basename = "lld.id";
 
@@ -653,19 +653,13 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
             try fs.cwd().copyFile(the_object_path, fs.cwd(), full_out_path, .{});
         }
     } else {
-        const is_obj = self.base.options.output_mode == .Obj;
-
         // Create an LLD command line and invoke it.
         var argv = std.ArrayList([]const u8).init(self.base.allocator);
         defer argv.deinit();
         // We will invoke ourselves as a child process to gain access to LLD.
         // This is necessary because LLD does not behave properly as a library -
         // it calls exit() and does not reset all global data between invocations.
         try argv.appendSlice(&[_][]const u8{ comp.self_exe_path.?, "wasm-ld" });
-        if (is_obj) {
-            try argv.append("-r");
-        }
-
         try argv.append("-error-limit=0");
 
         if (self.base.options.lto) {
@@ -697,16 +691,38 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation) !void {
             full_out_path,
         });
 
-        if (link_in_crt) {
-            // TODO work out if we want standard crt, a reactor or a command
-            try argv.append(try comp.get_libc_crt_file(arena, "crt.o"));
-        }
+        if (target.os.tag == .wasi) {
+            if (self.base.options.link_libc and self.base.options.output_mode == .Exe) {
+                // TODO work out if we want standard crt, a reactor or a command
+                try argv.append(try comp.get_libc_crt_file(arena, "crt1.o"));
+            }
+
+            const is_exe_or_dyn_lib = self.base.options.output_mode == .Exe or
+                (self.base.options.output_mode == .Lib and self.base.options.link_mode == .Dynamic);
+            if (is_exe_or_dyn_lib) {
+                const system_libs = self.base.options.system_libs.keys();
 
-        if (!is_obj and self.base.options.link_libc) {
-            try argv.append(try comp.get_libc_crt_file(arena, switch (self.base.options.link_mode) {
-                .Static => "libc.a",
-                .Dynamic => unreachable,
-            }));
+                for (system_libs) |link_lib| {
+                    if (mem.eql(u8, "wasi_snapshot_preview1", link_lib)) {
+                        // Any referenced symbol from this lib, will be undefined until
+                        // runtime as this lib is provided directly by the runtime.
+                        continue;
+                    }
+                    try argv.append(try std.fmt.allocPrint(arena, "-l{s}", .{link_lib}));
+                }
+
+                const wasi_emulated_libs = self.base.options.wasi_emulated_libs;
+                for (wasi_emulated_libs) |crt_file| {
+                    try argv.append(try comp.get_libc_crt_file(
+                        arena,
+                        wasi_libc.emulatedLibCRFileLibName(crt_file),
+                    ));
+                }
+
+                if (self.base.options.link_libc) {
+                    try argv.append(try comp.get_libc_crt_file(arena, "libc.a"));
+                }
+            }
         }
 
         // Positional arguments to the linker such as object files.

src/main.zig

@@ -15,6 +15,7 @@ const Package = @import("Package.zig");
 const build_options = @import("build_options");
 const introspect = @import("introspect.zig");
 const LibCInstallation = @import("libc_installation.zig").LibCInstallation;
+const wasi_libc = @import("wasi_libc.zig");
 const translate_c = @import("translate_c.zig");
 const Cache = @import("Cache.zig");
 const target_util = @import("target.zig");
@@ -616,6 +617,9 @@ fn buildOutputType(
     var system_libs = std.ArrayList([]const u8).init(gpa);
     defer system_libs.deinit();
 
+    var wasi_emulated_libs = std.ArrayList(wasi_libc.CRTFile).init(gpa);
+    defer wasi_emulated_libs.deinit();
+
     var clang_argv = std.ArrayList([]const u8).init(gpa);
     defer clang_argv.deinit();
 
@@ -1586,6 +1590,13 @@ fn buildOutputType(
             if (std.fs.path.isAbsolute(lib_name)) {
                 fatal("cannot use absolute path as a system library: {s}", .{lib_name});
             }
+            if (target_info.target.os.tag == .wasi) {
+                if (wasi_libc.getEmulatedLibCRTFile(lib_name)) |crt_file| {
+                    try wasi_emulated_libs.append(crt_file);
+                    _ = system_libs.orderedRemove(i);
+                    continue;
+                }
+            }
             i += 1;
         }
     }
@@ -1895,6 +1906,7 @@ fn buildOutputType(
         .framework_dirs = framework_dirs.items,
         .frameworks = frameworks.items,
         .system_libs = system_libs.items,
+        .wasi_emulated_libs = wasi_emulated_libs.items,
         .link_libc = link_libc,
         .link_libcpp = link_libcpp,
         .link_libunwind = link_libunwind,