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);
}
