Merge pull request #1867 from zoddicus/addWebBuild

CMakeLists.txt

@@ -9,6 +9,9 @@ set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 # Adhere to GNU filesystem layout conventions
 include(GNUInstallDirs)
 
+# Needed for CMAKE_DEPENDENT_OPTION macro
+include(CMakeDependentOption)
+
 option(BUILD_SHARED_LIBS "Build Shared Libraries" OFF)
 
 set(LIB_TYPE STATIC)
@@ -28,7 +31,10 @@ option(ENABLE_GLSLANG_BINARIES "Builds glslangValidator and spirv-remap" ON)
 
 option(ENABLE_NV_EXTENSIONS "Enables support of Nvidia-specific extensions" ON)
 
-option(ENABLE_HLSL "Enables HLSL input support" ON)
+option(ENABLE_GLSLANG_WEB "Reduces glslang to minumum needed for web use" OFF)
+option(ENABLE_EMSCRIPTEN_SINGLE_FILE "If using emscripten, enables SINGLE_FILE build" OFF)
+
+CMAKE_DEPENDENT_OPTION(ENABLE_HLSL "Enables HLSL input support" ON "NOT ENABLE_GLSLANG_WEB" OFF)
 
 option(ENABLE_OPT "Enables spirv-opt capability if present" ON)
 
@@ -98,6 +104,32 @@ elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "MSVC")
     add_compile_options(/GR-) # Disable RTTI
 endif()
 
+if(ENABLE_GLSLANG_WEB)
+    if(EMSCRIPTEN)
+        add_compile_options(-Os -fno-exceptions)
+        add_compile_options("SHELL: -s WASM=1")
+        add_compile_options("SHELL: -s WASM_OBJECT_FILES=0")
+        add_link_options(-Os)
+        add_link_options("SHELL: -s FILESYSTEM=0")
+        add_link_options("SHELL: --llvm-lto 1")
+        add_link_options("SHELL: --closure 1")
+        add_link_options("SHELL: -s ENVIRONMENT=web,worker")
+        add_link_options("SHELL: -s ALLOW_MEMORY_GROWTH=1")
+
+        add_link_options("SHELL: -s MODULARIZE=1")
+        if(ENABLE_EMSCRIPTEN_SINGLE_FILE)
+            add_link_options("SHELL: -s SINGLE_FILE=1")
+        endif(ENABLE_EMSCRIPTEN_SINGLE_FILE)
+    else()
+      if(MSVC)
+        add_compile_options(/Os /GR-)
+      else()
+        add_compile_options(-Os -fno-exceptions)
+        add_link_options(-Os)
+      endif()
+    endif(EMSCRIPTEN)
+endif(ENABLE_GLSLANG_WEB)
+
 # Request C++11
 if(${CMAKE_VERSION} VERSION_LESS 3.1)
     # CMake versions before 3.1 do not understand CMAKE_CXX_STANDARD

README.md

@@ -163,6 +163,22 @@ bison --defines=MachineIndependent/glslang_tab.cpp.h
 The above command is also available in the bash script at
 `glslang/updateGrammar`.
 
+### WASM for the the Web
+
+Use the steps in [Build Steps](#build-steps), which following notes/exceptions:
+* `emsdk` needs to be present in your executable search path, *PATH* for
+  Bash-like enivironments
+  + Instructions located
+    [here](https://emscripten.org/docs/getting_started/downloads.html#sdk-download-and-install)
+* Do not checkout SPIRV-Tools into `External`
+  + Does not work correctly with emscripten out of the box and we don't want it
+    in the build anyway. *TBD* Have build ignore SPIRV-Tools for web build
+* Wrap call to `cmake` using `emconfigure` with ENABLE_GLSLANG_WEB=ON:
+  + e.g. For Linux, `emconfigure cmake -DCMAKE_BUILD_TYPE=Release
+    -DENABLE_GLSLANG_WEB=ON -DCMAKE_INSTALL_PREFIX="$(pwd)/install" ..`
+* To get a 'true' minimized build, make sure to use `brotli` to compress the .js
+  and .wasm files
+
 Testing
 -------
 

glslang/CMakeLists.txt

@@ -122,3 +122,15 @@ if(ENABLE_GLSLANG_INSTALL)
         install(FILES ${file} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/glslang/${dir})
     endforeach()
 endif(ENABLE_GLSLANG_INSTALL)
+
+if(ENABLE_GLSLANG_WEB)
+    add_executable(glslang.js glslang.js.cpp)
+    glslang_set_link_args(glslang.js)
+    target_link_libraries(glslang.js glslang SPIRV)
+    if(EMSCRIPTEN)
+        set_target_properties(glslang.js PROPERTIES
+          OUTPUT_NAME "glslang"
+          SUFFIX ".js"
+          LINK_FLAGS "--bind")
+    endif(EMSCRIPTEN)
+endif(ENABLE_GLSLANG_WEB)