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[Emscripten port] Improve emcc flags #6349

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Merged
merged 1 commit into from
Feb 26, 2024
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[Emscripten port] Improve emcc flags #6349

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19 changes: 18 additions & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,9 @@ option(BUILD_FOR_BROWSER "Build binaryen toolchain utilities for the browser" OF
# Turn this on to use the Wasm EH feature instead of emscripten EH in the wasm/BinaryenJS builds
option(EMSCRIPTEN_ENABLE_WASM_EH "Enable Wasm EH feature in emscripten build" OFF)

# Turn this on to use pthreads feature in the wasm/BinaryenJS builds
option(EMSCRIPTEN_ENABLE_PTHREADS "Enable pthreads in emscripten build" OFF)

# For git users, attempt to generate a more useful version string
if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/.git)
find_package(Git QUIET REQUIRED)
Expand Down Expand Up @@ -342,6 +345,17 @@ if(EMSCRIPTEN)
add_compile_flag("-sDISABLE_EXCEPTION_CATCHING=0")
add_link_flag("-sDISABLE_EXCEPTION_CATCHING=0")
endif()
if(EMSCRIPTEN_ENABLE_PTHREADS)
add_compile_flag("-pthread")
add_link_flag("-pthread")
# Use mimalloc to avoid a 5x slowdown:
# https://github.com/emscripten-core/emscripten/issues/15727#issuecomment-1960295018
add_link_flag("-sMALLOC=mimalloc")
# Disable the warning on pthreads+memory growth (we are not much affected by
# it as there is little wasm-JS transfer of data, almost all work is inside
# the wasm).
add_link_flag("-Wno-pthreads-mem-growth")
endif()
# In the browser, there is no natural place to provide commandline arguments
# for a commandline tool, so let the user run the main entry point themselves
# and pass in the arguments there.
Expand All @@ -356,7 +370,6 @@ if(EMSCRIPTEN)
else()
# On Node.js, make the tools immediately usable.
add_link_flag("-sNODERAWFS")
add_link_flag("-sSINGLE_FILE")
endif()
# in opt builds, LTO helps so much (>20%) it's worth slow compile times
add_nondebug_compile_flag("-flto")
Expand Down Expand Up @@ -461,6 +474,9 @@ if(EMSCRIPTEN)
target_link_libraries(binaryen_wasm "-sFILESYSTEM")
target_link_libraries(binaryen_wasm "-sEXPORT_NAME=Binaryen")
target_link_libraries(binaryen_wasm "-sNODERAWFS=0")
# Emit a single file for convenience of people using binaryen.js as a library,
# so they only need to distribute a single file.
target_link_libraries(binaryen_wasm "-sSINGLE_FILE")
target_link_libraries(binaryen_wasm "-sEXPORT_ES6")
target_link_libraries(binaryen_wasm "-sEXPORTED_RUNTIME_METHODS=stringToUTF8OnStack,stringToAscii")
target_link_libraries(binaryen_wasm "-sEXPORTED_FUNCTIONS=_malloc,_free")
Expand Down Expand Up @@ -493,6 +509,7 @@ if(EMSCRIPTEN)
target_link_libraries(binaryen_js "-sFILESYSTEM=1")
endif()
target_link_libraries(binaryen_js "-sNODERAWFS=0")
target_link_libraries(binaryen_js "-sSINGLE_FILE")
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Why do we need to specify this twice? i.e. do we not have a place to specify flag for both _js and _wasm?

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We have some duplication here that we've never figured out a way to remove... I'm not sure if CMake has a way? We basically want to "inherit" one target from another.

target_link_libraries(binaryen_js "-sEXPORT_NAME=Binaryen")
# Currently, js_of_ocaml can only process ES5 code
if(JS_OF_OCAML)
Expand Down