Compile Binaryen to WebAssembly (#2503)

This PR enables compiling Binaryen to WebAssembly when building binaryen.js. Since WebAssembly is best compiled and instantiated asynchronously in browsers, it also adds a new mechanism to tell if respectively when the module is ready by means of one of the following:

// Using a promise
const binaryen = require("binaryen");
binaryen.ready.then(() => {
  ... use normally ...
});

// Using await
const binaryen = require("binaryen");
(async () => {
  await binaryen.ready;
  ... use normally ...
})();

// Where top-level await is available
const binaryen = await require("binaryen").ready;
... use normally ...

One can also tell if Binaryen is already ready (for example when assuming it in follow-up code) by:

if (/* we already know that */ binaryen.isReady) {
  ... use normally ...
} else {
  throw Error("Binaryen is supposed to be ready here but isn't");
}

The JS test cases have been updated accordingly by wrapping everything in a test function and invoking it once ready. Documentation will have to be updated as well to cover this of course. New file size is about 2.5mb, even though the Wasm becomes inlined into the JS file which makes distribution across different environments a lot easier.

Also makes building binaryen (to either js or wasm) emit binaryen.js, and not binaryen_js.js etc.

Supersedes and thus fixes #1381
With .ready it also fixes #2452

Author: dcodeIO

.gitattributes

@@ -1 +1,2 @@
 *.sh text eol=lf
+test/binaryen.js/*.txt text eol=lf

CHANGELOG.md

@@ -32,6 +32,10 @@ Current Trunk
 - Add the ability to create multivalue Types in the C and JS APIs.
 - Remove named function types. They are replaced by `params` and `results` types
   local to each function.
+- Binaryen.js can now be compiled to Wasm using the `binaryen_wasm` target.
+  Unlike the JS variant, the Wasm variant requires asynchronously awaiting the
+  Wasm blob's instantiation and initialization before being usable, using the
+  `binaryen.ready` promise, e.g. `binaryen.ready.then(() => ...)`.
 
 v88
 ---

CMakeLists.txt

@@ -365,22 +365,40 @@ install(TARGETS wasm-reduce DESTINATION ${CMAKE_INSTALL_BINDIR})
 # binaryen.js
 #
 # Note that we can't emit binaryen.js directly, as there is libbinaryen already
-# declared earlier, so we create binaryen_js.js, which must then be copied.
+# declared earlier, so we create binaryen_wasm/js.js, which must then be copied.
+# Note that SHELL: is needed as otherwise cmake will coalesce -s link flags
+# in an incorrect way for emscripten.
 if(EMSCRIPTEN)
-  set(binaryen_js_SOURCES
+  set(binaryen_emscripten_SOURCES
     src/binaryen-c.cpp
   )
+
+  # binaryen.js WebAssembly variant
+  add_executable(binaryen_wasm
+                 ${binaryen_emscripten_SOURCES})
+  target_link_libraries(binaryen_wasm wasm asmjs emscripten-optimizer passes ir cfg support wasm)
+  target_link_libraries(binaryen_wasm "-s MODULARIZE_INSTANCE=1")
+  target_link_libraries(binaryen_wasm "-s NO_FILESYSTEM=0")
+  target_link_libraries(binaryen_wasm "-s NODERAWFS=0")
+  target_link_libraries(binaryen_wasm "-s EXPORT_NAME=Binaryen")
+  target_link_libraries(binaryen_wasm "--post-js ${CMAKE_CURRENT_SOURCE_DIR}/src/js/binaryen.js-post.js")
+  target_link_libraries(binaryen_wasm optimized "--closure 1")
+  target_link_libraries(binaryen_wasm optimized "--llvm-lto 1")
+  target_link_libraries(binaryen_wasm debug "--profiling")
+  set_property(TARGET binaryen_wasm PROPERTY CXX_STANDARD 14)
+  set_property(TARGET binaryen_wasm PROPERTY CXX_STANDARD_REQUIRED ON)
+  install(TARGETS binaryen_wasm DESTINATION ${CMAKE_INSTALL_BINDIR})
+
+  # binaryen.js JavaScript variant
   add_executable(binaryen_js
-                 ${binaryen_js_SOURCES})
+                 ${binaryen_emscripten_SOURCES})
   target_link_libraries(binaryen_js wasm asmjs emscripten-optimizer passes ir cfg support wasm)
-  # note that SHELL: is needed as otherwise cmake will coalesce -s link flags
-  # in an incorrect way for emscripten
   target_link_libraries(binaryen_js "-s WASM=0")
+  target_link_libraries(binaryen_js "-s WASM_ASYNC_COMPILATION=0")
   if(${CMAKE_CXX_COMPILER_VERSION} STREQUAL "6.0.1")
     # only valid with fastcomp and WASM=0
-    target_link_libraries(binaryen_js "-s ELIMINATE_DUPLICATE_FUNCTIONS=1")
+    target_link_libraries(binaryen_js "-s ELIMINATE_DUPLICATE_FUNCTIONS=1")	
   endif()
-  target_link_libraries(binaryen_js "-s WASM_ASYNC_COMPILATION=0")
   target_link_libraries(binaryen_js "-s MODULARIZE_INSTANCE=1")
   target_link_libraries(binaryen_js "-s NO_FILESYSTEM=0")
   target_link_libraries(binaryen_js "-s NODERAWFS=0")
@@ -393,6 +411,9 @@ if(EMSCRIPTEN)
   set_property(TARGET binaryen_js PROPERTY CXX_STANDARD 14)
   set_property(TARGET binaryen_js PROPERTY CXX_STANDARD_REQUIRED ON)
   install(TARGETS binaryen_js DESTINATION ${CMAKE_INSTALL_BINDIR})
+
+  # always emit as 'binaryen.js'
+  set_target_properties(binaryen_wasm binaryen_js PROPERTIES OUTPUT_NAME "binaryen")
 endif()
 
 # Testing

scripts/test/shared.py

@@ -184,9 +184,7 @@ def is_exe(fpath):
 WASM_METADCE = [os.path.join(options.binaryen_bin, 'wasm-metadce')]
 WASM_EMSCRIPTEN_FINALIZE = [os.path.join(options.binaryen_bin,
                                          'wasm-emscripten-finalize')]
-# Due to cmake limitations, we emit binaryen_js.js (see CMakeLists.txt
-# for why).
-BINARYEN_JS = os.path.join(options.binaryen_bin, 'binaryen_js.js')
+BINARYEN_JS = os.path.join(options.binaryen_bin, 'binaryen.js')
 
 
 def wrap_with_valgrind(cmd):