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Properly set EMAR for Interprocedural Optimization #14

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Properly set EMAR for Interprocedural Optimization #14

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4e52174
Properly set EMAR for Interprocedural Optimization
Skylion007 May 18, 2021
4bce5da
Adds `-flto`
Skylion007 May 18, 2021
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8 changes: 6 additions & 2 deletions generic/Emscripten-wasm.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,10 @@ set(CMAKE_CXX_COMPILER "${EMSCRIPTEN_PREFIX}/em++${EMCC_SUFFIX}")
# and doing it everywhere.
set(CMAKE_AR "${EMSCRIPTEN_PREFIX}/emar${EMCC_SUFFIX}" CACHE PATH "Path to Emscripten ar")
set(CMAKE_RANLIB "${EMSCRIPTEN_PREFIX}/emranlib${EMCC_SUFFIX}" CACHE PATH "Path to Emscripten ranlib")
set(CMAKE_C_COMPILER_AR "${CMAKE_AR}")
set(CMAKE_CXX_COMPILER_AR "${CMAKE_AR}")
set(CMAKE_C_COMPILER_RANLIB "${CMAKE_RANLIB}")
set(CMAKE_CXX_COMPILER_RANLIB "${CMAKE_RANLIB}")
Comment on lines +60 to +63
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I would have suspected that CMake initializes these automatically based on CMAKE_AR and CMAKE_RANLIB right after the toolchain file, but I assume that is not the case?

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@Squareys I wish. Emscriptem's toolchain does properly handle it, but Magnum's doesn't sadly.


set(CMAKE_FIND_ROOT_PATH ${CMAKE_FIND_ROOT_PATH}
"${EMSCRIPTEN_TOOLCHAIN_PATH}"
Expand All @@ -76,5 +80,5 @@ set(CMAKE_SYSTEM_PREFIX_PATH ${CMAKE_FIND_ROOT_PATH})
cmake_minimum_required(VERSION 3.7)
set(CMAKE_CXX_FLAGS_INIT "-s WASM=1")
set(CMAKE_EXE_LINKER_FLAGS_INIT "-s WASM=1")
set(CMAKE_CXX_FLAGS_RELEASE_INIT "-DNDEBUG -O3")
set(CMAKE_EXE_LINKER_FLAGS_RELEASE_INIT "-O3 --llvm-lto 1")
set(CMAKE_CXX_FLAGS_RELEASE_INIT "-DNDEBUG -O3 -flto")
set(CMAKE_EXE_LINKER_FLAGS_RELEASE_INIT "-O3 --llvm-lto 1 -flto")
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@mosra For your reference, here's the documentation for that: https://emscripten.org/docs/compiling/WebAssembly.html#backends

--llvm-lto 1 is for the deprecated fastcomp backend (removed in emsc 2.0.0), -flto(=full|thin) is the new way of achieving link-time optimization

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Ah, found #13, so you are already aware

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@Squareys Yeah, unfortunately @mosra mentioned we need to support the fastcomp backend. Do you know an easy to way to check if we are using fastcomp or the more modern clang?

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Also I was having trouble with the default build running into issues with ThinLTO. @Squareys have you gotten ThinLTO working with build? I got complaints from the wasm-ld.