gpu-dawn: various windows support improvements

gpu-dawn/build.zig

@@ -60,8 +60,7 @@ pub const Options = struct {
     // TODO(build-system): enable on Windows if we can cross compile Vulkan
     vulkan: ?bool = null,
 
-    /// Defaults to true on Windows, Linux
-    // TODO(build-system): not respected at all currently
+    /// Defaults to true on Linux
     desktop_gl: ?bool = null,
 
     /// Defaults to true on Android, Linux, Windows, Emscripten
@@ -96,9 +95,9 @@ pub const Options = struct {
         if (options.metal == null) options.metal = tag.isDarwin();
         if (options.vulkan == null) options.vulkan = tag == .fuchsia or linux_desktop_like;
 
-        // TODO(build-system): respect these options / defaults
-        if (options.desktop_gl == null) options.desktop_gl = linux_desktop_like; // TODO(build-system): add windows
-        options.opengl_es = false;
+        // TODO(build-system): technically Dawn itself defaults desktop_gl to true on Windows.
+        if (options.desktop_gl == null) options.desktop_gl = linux_desktop_like;
+        options.opengl_es = false; // TODO(build-system): OpenGL ES
         // if (options.opengl_es == null) options.opengl_es = tag == .windows or tag == .emscripten or target.isAndroid() or linux_desktop_like;
         return options;
     }
@@ -178,6 +177,9 @@ fn linkFromSource(b: *Builder, step: *std.build.LibExeObjStep, options: Options)
 }
 
 fn ensureSubmodules(allocator: std.mem.Allocator) !void {
+    if (std.process.getEnvVarOwned(allocator, "NO_ENSURE_SUBMODULES")) |no_ensure_submodules| {
+        if (std.mem.eql(u8, no_ensure_submodules, "true")) return;
+    } else |_| {}
     const child = try std.ChildProcess.init(&.{ "git", "submodule", "update", "--init", "--recursive" }, allocator);
     child.cwd = thisDir();
     child.stderr = std.io.getStdErr();
@@ -419,7 +421,7 @@ fn buildLibDawnCommon(b: *Builder, step: *std.build.LibExeObjStep, options: Opti
     var cpp_flags = std.ArrayList([]const u8).init(b.allocator);
     cpp_flags.appendSlice(flags.items) catch unreachable;
     options.appendFlags(&cpp_flags, false, true) catch unreachable;
-    addCSourceFiles(b, lib, cpp_sources.items, cpp_flags.items);
+    lib.addCSourceFiles(cpp_sources.items, cpp_flags.items);
     return lib;
 }
 
@@ -454,7 +456,7 @@ fn buildLibDawnPlatform(b: *Builder, step: *std.build.LibExeObjStep, options: Op
         cpp_sources.append(abs_path) catch unreachable;
     }
 
-    addCSourceFiles(b, lib, cpp_sources.items, cpp_flags.items);
+    lib.addCSourceFiles(cpp_sources.items, cpp_flags.items);
     return lib;
 }
 
@@ -736,7 +738,7 @@ fn buildLibDawnNative(b: *Builder, step: *std.build.LibExeObjStep, options: Opti
     var cpp_flags = std.ArrayList([]const u8).init(b.allocator);
     cpp_flags.appendSlice(flags.items) catch unreachable;
     options.appendFlags(&cpp_flags, false, true) catch unreachable;
-    addCSourceFiles(b, lib, cpp_sources.items, cpp_flags.items);
+    lib.addCSourceFiles(cpp_sources.items, cpp_flags.items);
     return lib;
 }
 
@@ -891,7 +893,7 @@ fn buildLibTint(b: *Builder, step: *std.build.LibExeObjStep, options: Options) *
     var cpp_flags = std.ArrayList([]const u8).init(b.allocator);
     cpp_flags.appendSlice(flags.items) catch unreachable;
     options.appendFlags(&cpp_flags, false, true) catch unreachable;
-    addCSourceFiles(b, lib, cpp_sources.items, cpp_flags.items);
+    lib.addCSourceFiles(cpp_sources.items, cpp_flags.items);
     return lib;
 }
 
@@ -1024,6 +1026,7 @@ fn buildLibAbseilCpp(b: *Builder, step: *std.build.LibExeObjStep, options: Optio
         include("libs/dawn"),
         include("libs/dawn/third_party/abseil-cpp"),
     }) catch unreachable;
+    if (target.os.tag == .windows) flags.append("-DABSL_FORCE_THREAD_IDENTITY_MODE=2") catch unreachable;
 
     // absl
     appendLangScannedSources(b, lib, options, .{
@@ -1160,7 +1163,7 @@ fn buildLibDawnUtils(b: *Builder, step: *std.build.LibExeObjStep, options: Optio
     var cpp_flags = std.ArrayList([]const u8).init(b.allocator);
     cpp_flags.appendSlice(flags.items) catch unreachable;
     options.appendFlags(&cpp_flags, false, true) catch unreachable;
-    addCSourceFiles(b, lib, cpp_sources.items, cpp_flags.items);
+    lib.addCSourceFiles(cpp_sources.items, cpp_flags.items);
     return lib;
 }
 
@@ -1172,29 +1175,6 @@ fn thisDir() []const u8 {
     return std.fs.path.dirname(@src().file) orelse ".";
 }
 
-// TODO(build-system): This and divideSources are needed to avoid Windows process creation argument
-// length limits. This should probably be fixed in Zig itself, not worked around here.
-fn addCSourceFiles(b: *Builder, step: *std.build.LibExeObjStep, sources: []const []const u8, flags: []const []const u8) void {
-    for (divideSources(b, sources) catch unreachable) |divided| step.addCSourceFiles(divided, flags);
-}
-
-fn divideSources(b: *Builder, sources: []const []const u8) ![]const []const []const u8 {
-    var divided = std.ArrayList([]const []const u8).init(b.allocator);
-    var current = std.ArrayList([]const u8).init(b.allocator);
-    var current_size: usize = 0;
-    for (sources) |src| {
-        if (current_size + src.len >= 30000) {
-            try divided.append(current.items);
-            current = std.ArrayList([]const u8).init(b.allocator);
-            current_size = 0;
-        }
-        current_size += src.len;
-        try current.append(src);
-    }
-    try divided.append(current.items);
-    return divided.items;
-}
-
 fn appendLangScannedSources(
     b: *Builder,
     step: *std.build.LibExeObjStep,
@@ -1244,7 +1224,7 @@ fn appendScannedSources(b: *Builder, step: *std.build.LibExeObjStep, args: struc
     for (args.rel_dirs) |rel_dir| {
         try scanSources(b, &sources, rel_dir, args.extensions, args.excluding, args.excluding_contains);
     }
-    addCSourceFiles(b, step, sources.items, args.flags);
+    step.addCSourceFiles(sources.items, args.flags);
 }
 
 /// Scans rel_dir for sources ending with one of the provided extensions, excluding relative paths

gpu-dawn/src/dawn/hello_triangle.zig

@@ -15,7 +15,7 @@ pub fn main() !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     var allocator = gpa.allocator();
 
-    const setup = try sample_utils.setup();
+    const setup = try sample_utils.setup(allocator);
     const queue = c.wgpuDeviceGetQueue(setup.device);
 
     var descriptor = std.mem.zeroes(c.WGPUSwapChainDescriptor);

gpu-dawn/src/dawn/sample_utils.zig

@@ -51,8 +51,17 @@ const Setup = struct {
     window: glfw.Window,
 };
 
-fn detectBackendType() c.WGPUBackendType {
-    if (std.os.getenv("WGPU_BACKEND")) |backend| {
+fn getEnvVarOwned(allocator: std.mem.Allocator, key: []const u8) error{ OutOfMemory, InvalidUtf8 }!?[]u8 {
+    return std.process.getEnvVarOwned(allocator, key) catch |err| switch (err) {
+        error.EnvironmentVariableNotFound => @as(?[]u8, null),
+        else => |e| e,
+    };
+}
+
+fn detectBackendType(allocator: std.mem.Allocator) !c.WGPUBackendType {
+    const WGPU_BACKEND = try getEnvVarOwned(allocator, "WGPU_BACKEND");
+    if (WGPU_BACKEND) |backend| {
+        defer allocator.free(backend);
         if (std.ascii.eqlIgnoreCase(backend, "opengl")) return c.WGPUBackendType_OpenGL;
         if (std.ascii.eqlIgnoreCase(backend, "opengles")) return c.WGPUBackendType_OpenGLES;
         if (std.ascii.eqlIgnoreCase(backend, "d3d11")) return c.WGPUBackendType_D3D11;
@@ -82,8 +91,8 @@ fn backendTypeString(t: c.WGPUBackendType) []const u8 {
     };
 }
 
-pub fn setup() !Setup {
-    const backend_type = detectBackendType();
+pub fn setup(allocator: std.mem.Allocator) !Setup {
+    const backend_type = try detectBackendType(allocator);
     const cmd_buf_type = CmdBufType.none;
 
     try glfw.init(.{});