예제 #1
0
    public static EmscriptenDynamicLinker ConfigureEmscriptenLinkerFor(EmscriptenDynamicLinker e,
                                                                       string variation, bool enableManagedDebugger)
    {
        var linkflags = new Dictionary <string, string>
        {
            // Bee defaults to PRECISE_F32=2, which is not an interesting feature for Dots. In Dots asm.js builds, we don't
            // care about single-precision floats, but care more about code size.
            { "PRECISE_F32", "0" },
            // No exceptions machinery needed, saves code size
            { "DISABLE_EXCEPTION_CATCHING", "1" },
            //// No virtual filesystem needed, saves code size
            { "NO_FILESYSTEM", "1" },
            // Make generated builds only ever executable from web, saves code size.
            // TODO: if/when we are generating a build for node.js test harness purposes, remove this line.
            { "ENVIRONMENT", "web" },
            // In -Oz builds, Emscripten does compile time global initializer evaluation in hope that it can
            // optimize away some ctors that can be compile time executed. This does not really happen often,
            // and with MINIMAL_RUNTIME we have a better "super-constructor" approach that groups all ctors
            // together into one, and that saves more code size. Unfortunately grouping constructors is
            // not possible if EVAL_CTORS is used, so disable EVAL_CTORS to enable grouping.
            { "EVAL_CTORS", "0" },
            // We don't want malloc() failures to trigger program exit and abort handling, but instead behave
            // like C runtimes do, and make malloc() return null. This saves code size and lets our code
            // handle oom failures.
            { "ABORTING_MALLOC", "0" },
            // By default the musl C runtime used by Emscripten is POSIX errno aware. We do not care about
            // errno, so opt out from errno management to save a tiny bit of performance and code size.
            { "SUPPORT_ERRNO", "0" },
            // Safari does not support WebAssembly.instantiateStreaming(), so revert to the older
            // WebAssembly.instantiate() API. This has the drawback that WebAssembly compilation will not
            // occur while downloading the .wasm file, but enables Safari compatibility.
            { "STREAMING_WASM_COMPILATION", "0" }
        };

        if (enableManagedDebugger)
        {
            linkflags["PROXY_POSIX_SOCKETS"] = "1";
        }

        if (e.Toolchain.Architecture is AsmJsArchitecture)
        {
            linkflags["LEGACY_VM_SUPPORT"] = "1";
            e = e.WithSeparateAsm(true);
        }

        if (variation == "debug" || variation == "develop")
        {
            linkflags["ASSERTIONS"]       = "2";
            linkflags["DEMANGLE_SUPPORT"] = "1";
        }
        else
        {
            linkflags["ASSERTIONS"] = "0";
            linkflags["AGGRESSIVE_VARIABLE_ELIMINATION"] = "1";
            linkflags["ELIMINATE_DUPLICATE_FUNCTIONS"]   = "1";
        }

        if (BuildSettingsContent != null &&
            BuildSettingsContent.TryGetValue("emscriptenLinkSettings", out var emscriptenLinkSettingsToken) &&
            emscriptenLinkSettingsToken is JObject emscriptenLinkSettings)
        {
            foreach (var setting in emscriptenLinkSettings)
            {
                linkflags[setting.Key] = setting.Value.Value <string>();
            }
        }

        e = e.WithEmscriptenSettings(linkflags);
        e = e.WithNoExitRuntime(true);

        switch (variation)
        {
        case "debug":
            e = e.WithDebugLevel("3");
            e = e.WithOptLevel("0");
            e = e.WithLinkTimeOptLevel(0);
            e = e.WithEmitSymbolMap(true);
            break;

        case "develop":
            e = e.WithDebugLevel("2");
            e = e.WithOptLevel("1");
            e = e.WithLinkTimeOptLevel(0);
            e = e.WithEmitSymbolMap(false);
            break;

        case "release":
            e = e.WithDebugLevel("0");
            e = e.WithOptLevel("z");
            e = e.WithLinkTimeOptLevel(3);
            e = e.WithEmitSymbolMap(true);
            break;

        default:
            throw new ArgumentException();
        }

        e = e.WithMinimalRuntime(EmscriptenMinimalRuntimeMode.EnableDangerouslyAggressive);

        // Bee is not yet aware of the new --closure-externs (and --closure-annotations) linker flags, so add them using the generic
        // escape hatch hook.
        e = e.WithCustomFlags_workaround(new[]
        {
            "--closure-externs", BuildProgram.BeeRoot.Combine("closure_externs.js").ToString().QuoteForProcessStart()
        });

        // TODO: Remove this line once Bee fix is in to support SystemLibrary() objects on web builds. Then restore
        // the line Libraries.Add(c => c.ToolChain.Platform is WebGLPlatform, new SystemLibrary("GL")); at the top of this file
        e = e.WithCustomFlags_workaround(new[] { "-lGL" });

        e = e.WithMemoryInitFile(e.Toolchain.Architecture is AsmJsArchitecture || RunInBackgroundWorker);

        if (RunInBackgroundWorker)
        {
            // Specify Emscripten -s USE_PTHREADS=1 at compile time, so that C++ code that is compiled will have
            // the __EMSCRIPTEN_PTHREADS__ preprocessor #define available to it to detect if code will be compiled
            // single- or multithreaded.
            e = e.WithCustomFlags_workaround(new[] { "-s USE_PTHREADS=1 " });
        }

        // Enables async requests for web IO and Disabling IndexDB support as this is not fully implemented yet in emscripten
        // Using custom flags as there appears to be no standard way to set the option in bee and passing the flags to the linker settings
        // normally will cause bee to error
        e = e.WithCustomFlags_workaround(new[] { "-s FETCH=1 -s FETCH_SUPPORT_INDEXEDDB=0" });

        return(e);
    }
    public static EmscriptenDynamicLinker ConfigureEmscriptenLinkerFor(EmscriptenDynamicLinker e,
                                                                       string variation, bool enableManagedDebugger)
    {
        bool runInBackgroundWorker = RunInBackgroundWorker || enableManagedDebugger;
        bool enableMultithreading  = EnableMultithreading || runInBackgroundWorker;

        var linkflags = new Dictionary <string, string>
        {
            // Bee defaults to PRECISE_F32=2, which is not an interesting feature for Dots. In Dots asm.js builds, we don't
            // care about single-precision floats, but care more about code size.
            { "PRECISE_F32", "0" },
            // No virtual filesystem needed, saves code size
            { "NO_FILESYSTEM", "1" },
            // Generate runtime code only for executing in web browser (and in a Web Worker if debugging)
            { "ENVIRONMENT", enableMultithreading ? "web,worker" : "web" },
            // Proxy all posix sockets calls to a sockets thread when managed debugging is enabled
            { "PROXY_POSIX_SOCKETS", enableManagedDebugger ? "1" : "0" },
            // No exceptions machinery needed when not debugging, saves code size
            { "DISABLE_EXCEPTION_CATCHING", enableManagedDebugger ? "0" : "1" },
            // In -Oz builds, Emscripten does compile time global initializer evaluation in hope that it can
            // optimize away some ctors that can be compile time executed. This does not really happen often,
            // and with MINIMAL_RUNTIME we have a better "super-constructor" approach that groups all ctors
            // together into one, and that saves more code size. Unfortunately grouping constructors is
            // not possible if EVAL_CTORS is used, so disable EVAL_CTORS to enable grouping.
            { "EVAL_CTORS", "0" },
            // By default the musl C runtime used by Emscripten is POSIX errno aware. We do not care about
            // errno, so opt out from errno management to save a tiny bit of performance and code size.
            { "SUPPORT_ERRNO", "0" },
            // IndexedDB not currently working with Fetch when MINIMAL_RUNTIME is used. (We don't need
            // it anyways as long as our content sizes are nice and small. Revisit when we have 50MB+
            // asset package files)
            { "FETCH_SUPPORT_INDEXEDDB", "0" },
            // We only utilize asynchronous Fetches, so do not need a dedicated Fetch Worker for sync fetches
            // on the background.
            { "USE_FETCH_WORKER", "0" },
            // Initial heap size is defined by TOTAL_MEMORY, but also enable the heap to grow at runtime with
            // ALLOW_MEMORY_GROWTH flag.
            { "ALLOW_MEMORY_GROWTH", "1" },
            // Remove support for OES_texture_half_float and OES_texture_half_float_linear extensions if
            // they are broken. See https://bugs.webkit.org/show_bug.cgi?id=183321,
            // https://bugs.webkit.org/show_bug.cgi?id=169999,
            // https://stackoverflow.com/questions/54248633/cannot-create-half-float-oes-texture-from-uint16array-on-ipad
            { "GL_DISABLE_HALF_FLOAT_EXTENSION_IF_BROKEN", "1" },
            // Use emmalloc_memalign to allocate VM GC memory with BDWGC so that the managed heap
            // uses the same allcoator as everything else.
            { "MALLOC", "emmalloc" },
        };

        if (enableMultithreading)
        {
            e = e.WithMultithreading_Linker(EmscriptenMultithreadingMode.Enabled);
        }

        if (runInBackgroundWorker)
        {
            // WebGL rendering will run in a background thread - proxy GL over to the main thread.
            linkflags["OFFSCREEN_FRAMEBUFFER"] = "1";

            // Enable the main() thread to launch in a Web Worker instead of the main browser thread.
            linkflags["PROXY_TO_PTHREAD"] = "1";
        }

        if (enableManagedDebugger)
        {
            e = e.WithCustomFlags_workaround(new[] { "-lwebsocket.js" });
        }

        if (e.Toolchain.Architecture is AsmJsArchitecture)
        {
            // Target the oldest of browsers when building to JavaScript.
            linkflags["LEGACY_VM_SUPPORT"] = "1";

            // In old fastcomp backend, we can separate the unreadable .asm.js content to its own .asm.js file.
            // In new LLVM backend, it is currently always separated if -s WASM=2 is set, or embedded inline
            // if -s WASM=0 is set, so this option does not apply there.
            if (!UseWasmBackend)
            {
                e = e.WithSeparateAsm(true);
            }
        }

        if (variation == "debug" || variation == "develop")
        {
            linkflags["ASSERTIONS"]       = "1";
            linkflags["DEMANGLE_SUPPORT"] = "1";
        }
        else
        {
            linkflags["ASSERTIONS"] = "0";
            linkflags["AGGRESSIVE_VARIABLE_ELIMINATION"] = "1";
            if (!UseWasmBackend) // This optimization pass only exists for the old fastcomp backend.
            {
                linkflags["ELIMINATE_DUPLICATE_FUNCTIONS"] = "1";
            }
        }

        e = e.WithEmscriptenSettings(linkflags);
        e = e.WithNoExitRuntime(true);

        switch (variation)
        {
        case "debug":
            e = e.WithDebugLevel("3");      // Preserve JS whitespace, function names, and LLVM debug info
            e = e.WithOptLevel("1");        // -O0 generates too much code from IL2CPP, must apply optimizations.
            e = e.WithLinkTimeOptLevel(0);
            e = e.WithEmitSymbolMap(false); // At -g3 no name minification occurs -> no symbols present
            e = e.WithCustomFlags_workaround(new[] {
                "-fno-inline"               // Disable inlining in debug builds for easier stepping through code.
            });
            break;

        case "develop":
            e = e.WithDebugLevel("2");     // Preserve JS whitespace and function names
            e = e.WithOptLevel("1");
            e = e.WithLinkTimeOptLevel(0);
            e = e.WithEmitSymbolMap(false);     // At -g2 no name minification occurs -> no symbols present
            break;

        case "release":
            e = e.WithDebugLevel("0");
            e = e.WithOptLevel("z");
            if (UseWasmBackend)
            {
                // Wasm backend uses the general LLVM/GCC -flto flag to enable LTO.
                e = e.WithCustomFlags_workaround(new[]
                {
                    "-flto"
                });
            }
            else
            {
                // Old fastcomp backend uses its own --llvm-lto <x> flag.
                e = e.WithLinkTimeOptLevel(3);
            }
            e = e.WithEmitSymbolMap(false);     // TODO: re-enable this after Emscripten update
            break;

        default:
            throw new ArgumentException();
        }

        e = e.WithMinimalRuntime(EmscriptenMinimalRuntimeMode.EnableDangerouslyAggressive);

        if (variation == "release" && EnableClosureCompiler)
        {
            // Inject -g1 (preserve whitespace) to Emscripten build so that error messages from Closure will be readable and not minified.
            // Closure will kill this whitespace as part of its minification.
            // TODO: Remove this the next time we update Emscripten (https://github.com/emscripten-core/emscripten/pull/12726)
            e = e.WithDebugLevel("1");

            e = e.WithCustomFlags_workaround(new[]
            {
                "--closure-args", ("--platform native --externs " + BuildProgram.BeeRoot.Combine("closure_externs.js").ToString()).QuoteForProcessStart(),
                "--closure", "1",
                "-s", "CLOSURE_WARNINGS=warn"
            });
        }

        // TODO: Remove this line once Bee fix is in to support SystemLibrary() objects on web builds. Then restore
        // the line Libraries.Add(c => c.ToolChain.Platform is WebGLPlatform, new SystemLibrary("GL")); at the top of this file
        e = e.WithCustomFlags_workaround(new[] { "-lGL" });

        // Target the Emscripten Fetch API for network requests.
        e = e.WithCustomFlags_workaround(new[] { "-s FETCH=1" });

        e = e.WithMemoryInitFile(e.Toolchain.Architecture is AsmJsArchitecture || (enableMultithreading && !UseWasmBackend));

        if (UseWasmBackend && e.Toolchain.Architecture is AsmJsArchitecture)
        {
            // Work around Binaryen multithreading bug: using more than 1 core is slower than using a single core!
            // TODO: Remove this after Emscripten update, where the issue has been fixed.
            // BUG: this does not actually work. Emcc is not a child of the Bee build process.
            // Switch to use something else.
            // Environment.SetEnvironmentVariable("BINARYEN_CORES", "1");
        }

        return(e);
    }