build(docker): use emulated pthreads

Until wasmtime supports threads in its C-API.

src/docker/itk-wasm-base/Dockerfile

@@ -43,6 +43,10 @@ RUN . /itk_wasm_env_vars.sh && sed -i -e "/^set(DCMTK_GIT_REPOSITORY/c\set(DCMTK
 RUN . /itk_wasm_env_vars.sh && sed -i -e "/^set(DCMTK_GIT_TAG/c\set(DCMTK_GIT_TAG \"${ITK_WASM_DCMTK_GIT_TAG}\")" \
     /ITK/Modules/ThirdParty/DCMTK/DCMTKGitTag.cmake
 
+# Current overwrite for the dockcross image to use emulated threads.
+# This can be removed after wasmtime supports threads in its C-API.
+COPY clang-wasi-threads-sysroot.sh clang++-wasi-threads-sysroot.sh /usr/local/bin/
+
 ARG CMAKE_BUILD_TYPE=Release
 
 ARG LDFLAGS

src/docker/itk-wasm-base/build.sh

@@ -31,14 +31,14 @@ done
 set -- "${newparams[@]}"  # overwrites the original positional params
 
 # Note: also need to set in wasi-sdk-pthread-itkwasm.cmake
-wasi_ld_flags="-flto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double"
-wasi_c_flags="-flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL"
+wasi_ld_flags="-D_WASI_EMULATED_PTHREAD -flto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double"
+wasi_c_flags="-lwasi-emulated-pthread -flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL"
 
 emscripten_debug_ld_flags="-fno-lto -s ALLOW_MEMORY_GROWTH=1 -s MAXIMUM_MEMORY=4GB"
 emscripten_debug_c_flags="-fno-lto -Wno-warn-absolute-paths"
 
-wasi_debug_ld_flags="-fno-lto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double"
-wasi_debug_c_flags="-fno-lto -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL"
+wasi_debug_ld_flags="-D_WASI_EMULATED_PTHREAD -fno-lto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double"
+wasi_debug_c_flags="-lwasi-emulated-pthread -fno-lto -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL"
 
 $exe $build_cmd $tag_flag quay.io/itkwasm/emscripten-base:latest-$host_arch \
         --build-arg IMAGE=quay.io/itkwasm/emscripten-base \

src/docker/itk-wasm-base/clang++-wasi-threads-sysroot.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env sh
+
+exec ${WASI_SDK_PATH}/bin/clang++ --target=wasm32-wasi-threads --sysroot=${WASI_SYSROOT} "$@"

src/docker/itk-wasm-base/clang-wasi-threads-sysroot.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env sh
+
+exec ${WASI_SDK_PATH}/bin/clang --target=wasm32-wasi-threads --sysroot=${WASI_SYSROOT} "$@"

src/docker/itk-wasm-base/wasi-sdk-pthread-itkwasm.cmake

@@ -4,15 +4,15 @@ set(CMAKE_SYSTEM_NAME WASI)
 set(CMAKE_SYSTEM_VERSION 1)
 set(CMAKE_SYSTEM_PROCESSOR wasm32)
 set(triple wasm32-wasi-threads)
-set(CMAKE_C_FLAGS "-pthread -matomics -mbulk-memory -flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL ${CMAKE_C_FLAGS}")
+set(CMAKE_C_FLAGS "-D_WASI_EMULATED_PTHREAD -mbulk-memory -flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL ${CMAKE_C_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} ${CMAKE_CXX_FLAGS}")
 # wasi-threads requires --import-memory.
 # wasi requires --export-memory.
 # (--export-memory is implicit unless --import-memory is given)
-set(CMAKE_EXE_LINKER_FLAGS "-Wl,--import-memory ${CMAKE_EXE_LINKER_FLAGS}")
+# set(CMAKE_EXE_LINKER_FLAGS "-Wl,--import-memory ${CMAKE_EXE_LINKER_FLAGS}")
 set(CMAKE_EXE_LINKER_FLAGS "-Wl,--export-memory ${CMAKE_EXE_LINKER_FLAGS}")
 # ITK-Wasm
-set(CMAKE_EXE_LINKER_FLAGS "-Wl,--initial-memory=8388608,--max-memory=4294967296,--shared-memory -flto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double ${CMAKE_EXE_LINKER_FLAGS}")
+set(CMAKE_EXE_LINKER_FLAGS "-lwasi-emulated-pthread -flto -lwasi-emulated-process-clocks -lwasi-emulated-signal -lc-printscan-long-double ${CMAKE_EXE_LINKER_FLAGS}")
 
 if(WIN32)
 	set(WASI_HOST_EXE_SUFFIX ".exe")