Tweaked Emscripten build flags to make WASM smaller

- Defined the compile/link flags as variables and reuse them
- Enabled LTO
- Forced -Os, since build type MinSizeRel doesn't seem to do anything
- Changed build type to Release, since the debug symbols add ~50MB to
  the .wasm files

C/tests/cmake/platform_emscripten.cmake

@@ -10,15 +10,12 @@ function(setup_build)
 
     target_compile_options(
         C4Tests PRIVATE
-        "-pthread"
-        "-fwasm-exceptions"
+        ${EMSCRIPTEN_COMPILE_FLAGS}
     )
 
     target_link_options(
         C4Tests PRIVATE
-        "-pthread"
-        "-fwasm-exceptions"
-        "-lembind"
+        ${EMSCRIPTEN_LINK_FLAGS}
         "SHELL:-s EXIT_RUNTIME=1"
         "SHELL:-s PTHREAD_POOL_SIZE=24"
         "SHELL:-s ALLOW_MEMORY_GROWTH=1"

CMakeLists.txt

@@ -150,7 +150,7 @@ elseif("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
     include("${PROJECT_SOURCE_DIR}/cmake/platform_linux_desktop.cmake")
 else()
     message(FATAL_ERROR "Unable to determine a supported platform from ${CMAKE_SYSTEM_NAME}")
-endif(MSVC)
+endif()
 
 check_threading()
 setup_globals()

LiteCore/tests/cmake/platform_emscripten.cmake

@@ -7,15 +7,12 @@ function(setup_build)
 
     target_compile_options(
         CppTests PRIVATE
-        "-pthread"
-        "-fwasm-exceptions"
+        ${EMSCRIPTEN_COMPILE_FLAGS}
     )
 
     target_link_options(
         CppTests PRIVATE
-        "-pthread"
-        "-fwasm-exceptions"
-        "-lembind"
+        ${EMSCRIPTEN_LINK_FLAGS}
         "SHELL:-s EXIT_RUNTIME=1"
         "SHELL:-s PTHREAD_POOL_SIZE=24"
         "SHELL:-s ALLOW_MEMORY_GROWTH=1"

Xcode/LiteCore.xcodeproj/project.pbxproj

@@ -1179,6 +1179,10 @@
 		275FF6661E42A90C005F90DD /* QueryParserTables.hh */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = QueryParserTables.hh; sourceTree = "<group>"; };
 		275FF6D11E4947E1005F90DD /* c4BaseTest.cc */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = c4BaseTest.cc; sourceTree = "<group>"; };
 		2760FBC826210AA0000F34C5 /* CollectionImpl.hh */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = CollectionImpl.hh; sourceTree = "<group>"; };
+		27614AA12C1CDCCB0065FBB5 /* cmake */ = {isa = PBXFileReference; lastKnownFileType = folder; name = cmake; path = ../cmake; sourceTree = "<group>"; };
+		27614AA52C1CDCEA0065FBB5 /* cmake */ = {isa = PBXFileReference; lastKnownFileType = folder; path = cmake; sourceTree = "<group>"; };
+		27614AA62C1CDD110065FBB5 /* cmake */ = {isa = PBXFileReference; lastKnownFileType = folder; path = cmake; sourceTree = "<group>"; };
+		27614AA72C1CDDB00065FBB5 /* cmake */ = {isa = PBXFileReference; lastKnownFileType = folder; path = cmake; sourceTree = "<group>"; };
 		2761F3EE1EE9CC58006D4BB8 /* CookieStore.cc */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = CookieStore.cc; sourceTree = "<group>"; };
 		2761F3EF1EE9CC58006D4BB8 /* CookieStore.hh */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = CookieStore.hh; sourceTree = "<group>"; };
 		2761F3F61EEA00C3006D4BB8 /* CookieStoreTest.cc */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; path = CookieStoreTest.cc; sourceTree = "<group>"; };
@@ -1915,6 +1919,7 @@
 				2708FE591CF4D0450022F721 /* LiteCoreTest.hh */,
 				274D040A1BA75E1C00FF7C35 /* main.cpp */,
 				2750735A1F4B5ECC003D2CCE /* CMakeLists.txt */,
+				27614AA72C1CDDB00065FBB5 /* cmake */,
 				2719253B23970F4E0053DDA6 /* replacedb */,
 			);
 			name = "C++ Tests";
@@ -2101,6 +2106,7 @@
 			children = (
 				2744B329241854F2005A194D /* README.md */,
 				2744B30C241854F2005A194D /* CMakeLists.txt */,
+				27614AA62C1CDD110065FBB5 /* cmake */,
 				2744B317241854F2005A194D /* BLIPConnection.hh */,
 				2744B319241854F2005A194D /* BLIP.hh */,
 				2744B31C241854F2005A194D /* MessageBuilder.hh */,
@@ -2234,6 +2240,7 @@
 				2783DF981D27436700F84E6E /* c4ThreadingTest.cc */,
 				2700BB612170117F00797537 /* EE */,
 				275073591F4B5E66003D2CCE /* CMakeLists.txt */,
+				27614AA52C1CDCEA0065FBB5 /* cmake */,
 				2719253323970C7F0053DDA6 /* data */,
 			);
 			path = tests;
@@ -2260,6 +2267,7 @@
 			children = (
 				273AD3CF18F4B23A007D8C23 /* README.md */,
 				275073581F4B5E13003D2CCE /* CMakeLists.txt */,
+				27614AA12C1CDCCB0065FBB5 /* cmake */,
 				2757DE551B9FC34E002EE261 /* API */,
 				2745B7CA26825F970012A17A /* docs */,
 				27E4871019217187007D8940 /* LiteCore */,

build_cmake/scripts/build_wasm_EE.sh

@@ -15,5 +15,5 @@ cd $SCRIPT_DIR/..
 mkdir -p wasm_EE
 cd wasm_EE
 
-emcmake cmake -DBUILD_ENTERPRISE=ON -DCMAKE_BUILD_TYPE=RelWithDebInfo ../..
+emcmake cmake -DBUILD_ENTERPRISE=ON -DCMAKE_BUILD_TYPE=Release ../..
 emmake make -j

cmake/platform_emscripten.cmake

@@ -4,10 +4,16 @@ macro(check_threading)
     message(STATUS "No threading checks needed for Emscripten")
 endmacro()
 
+set(EMSCRIPTEN_COMPILE_FLAGS "-pthread" "-fwasm-exceptions" "-Os")
+set(EMSCRIPTEN_LINK_FLAGS    "-pthread" "-fwasm-exceptions" "-lembind")
+
 function(setup_globals)
     setup_globals_unix()
 
-    set(EMSCRIPTEN_COMPILE_FLAGS "-pthread -fwasm-exceptions")
+    #if(NOT DISABLE_LTO_BUILD)
+        set(EMSCRIPTEN_COMPILE_FLAGS ${EMSCRIPTEN_COMPILE_FLAGS} "-flto" PARENT_SCOPE)
+        set(EMSCRIPTEN_LINK_FLAGS    ${EMSCRIPTEN_LINK_FLAGS}    "-flto" PARENT_SCOPE)
+    #endif()
 endfunction()
 
 function(set_litecore_source)
@@ -35,12 +41,11 @@ function(setup_litecore_build)
         LiteCore/Unix
     )
 
+    message(STATUS "Emscripten flags are ${EMSCRIPTEN_COMPILE_FLAGS}")
     foreach(platform LiteCoreObjects LiteCoreUnitTesting BLIPObjects CouchbaseSqlite3 SQLite3_UnicodeSN)
         target_compile_options(
             ${platform} PRIVATE
-            #${EMSCRIPTEN_COMPILE_FLAGS}
-            "-pthread"
-            "-fwasm-exceptions"
+            ${EMSCRIPTEN_COMPILE_FLAGS}
         )
     endforeach()