Rewrite build system to build everything from scratch.

This also builds a "true" thread-free llvm, and tries to otherwise
minimize LLVM changes in favour of libc changes.

.gitmodules

@@ -4,3 +4,6 @@
 [submodule "cpython"]
 	path = cpython
 	url = https://github.com/python/cpython.git
+[submodule "wasi-libc"]
+	path = wasi-libc
+	url = https://github.com/WebAssembly/wasi-libc.git

Makefile

@@ -1,61 +1,171 @@
-WASI_SDK_PREFIX ?= /opt/wasi-sdk/
-PYTHON ?= /usr/bin/env python3
+PYTHON := /usr/bin/env python3
 DIR := $(shell pwd)
-WASMTIME ?= $(shell which wasmtime)
-WASMTIME_FLAGS ?= --wasm max-wasm-stack=8388608 --dir {HOST_DIR}::{GUEST_DIR} \
-	--env {ENV_VAR_NAME}={ENV_VAR_VALUE} {PYTHON_WASM}
-
-.PHONY:
-all: test build/output.tar.br
-
-build/output.tar.br: build/output/python build/output/cpp
-	tar c -C build/output . | brotli --large_window=30 > $@
-
-build/output/python:
-	rm -rf "$@"
-	${PYTHON} cpython/Tools/wasm/wasi.py build \
-		--host-runner="${WASMTIME} run ${WASMTIME_FLAGS}" -- \
-		--prefix="${DIR}/$@" --exec-prefix="${DIR}/$@" \
-		--disable-test-modules
-	make -C cpython/cross-build/wasm32-wasi install
-
-build/libwasishim.a: wasi_shim.cpp
-	${WASI_SDK_PREFIX}/bin/clang++ -fno-exceptions -std=c++20 $< -O3 -c -o $@
-
-build/llvm-sources: llvm.patch
-	rm -rf "$@"
-	cp -r llvm "$@"
-	cd "$@" && patch -p1 < ${DIR}/llvm.patch
-
-build/llvm-build: build/llvm-sources build/libwasishim.a
-	cmake -B build/llvm-build build/llvm-sources/llvm \
-		-G Ninja -DCMAKE_BUILD_TYPE=Release \
-		-DWASI_SDK_PREFIX=${WASI_SDK_PREFIX} \
-		-DCMAKE_TOOLCHAIN_FILE=${WASI_SDK_PREFIX}/share/cmake/wasi-sdk.cmake \
-		-DLLVM_TARGETS_TO_BUILD=WebAssembly -DLLVM_ENABLE_PROJECTS="clang;lld" \
+SYSROOT := ${DIR}/build/sysroot
+WASMTIME := $(shell which wasmtime)
+CLANG_VERSION := $(shell /usr/bin/env bash ./llvm_version_major.sh llvm)
+
+OUTPUT := ${DIR}/build/output
+
+LLVM_HOST := ${DIR}/build/llvm-host
+
+WASM_CC := ${LLVM_HOST}/bin/clang
+WASM_CXX := ${LLVM_HOST}/bin/clang++
+WASM_NM := ${LLVM_HOST}/bin/llvm-nm
+WASM_AR := ${LLVM_HOST}/bin/llvm-ar
+WASM_CFLAGS := -ffile-prefix-map=${DIR}=/
+WASM_CXXFLAGS := -ffile-prefix-map=${DIR}=/
+WASM_LDFLAGS := -Wl,-z -Wl,stack-size=1048576
+MAKE := make
+
+all: ${OUTPUT}.DONE test
+
+build:
+	mkdir -p build
+
+build/llvm-host.BUILT: llvm | build
+	rsync -a --delete llvm/ build/llvm-host-src
+	cmake -S build/llvm-host-src/llvm -B build/llvm-host-build \
+		-DCMAKE_INSTALL_PREFIX="${DIR}/build/llvm-host" -DDEFAULT_SYSROOT=${SYSROOT} \
+		-DCMAKE_BUILD_TYPE=Release \
+		-DLLVM_TARGETS_TO_BUILD=WebAssembly -DLLVM_DEFAULT_TARGET_TRIPLE=wasm32-wasi \
+		-DLLVM_ENABLE_PROJECTS="clang;lld"
+	$(MAKE) -C build/llvm-host-build install
+	touch $@
+
+build/wasi-libc.BUILT: wasi-libc wasi-libc-polyfill.c wasi-libc.patch build/llvm-host.BUILT | build
+	rsync -a --delete wasi-libc/ build/wasi-libc
+	cd "build/wasi-libc" && patch -p1 < ${DIR}/wasi-libc.patch
+	cp wasi-libc-polyfill.c build/wasi-libc
+	$(MAKE) -C build/wasi-libc THREAD_MODEL=single \
+		CC=${WASM_CC} AR=$(WASM_AR) NM=${WASM_NM} EXTRA_CFLAGS="${WASI_CFLAGS} -O2 -DNDEBUG" \
+		INSTALL_DIR=${SYSROOT} install
+	touch $@
+
+build/llvm.SRC: llvm llvm.patch | build
+	rsync -a --delete llvm/ build/llvm-src
+	cd "build/llvm-src" && patch -p1 < ${DIR}/llvm.patch
+	touch $@
+
+build/compiler-rt-host.BUILT: build/llvm.SRC build/wasi-libc.BUILT
+	mkdir -p build/compiler-rt-build-host
+	cmake -B build/compiler-rt-build-host -S build/llvm-src/compiler-rt/lib/builtins \
+		-DWASM_PREFIX=${LLVM_HOST} -DCMAKE_TOOLCHAIN_FILE=${DIR}/cmake/toolchain.cmake \
+		-DCMAKE_C_FLAGS="-I${DIR} ${WASM_C}" \
+		-DCOMPILER_RT_BAREMETAL_BUILD=On \
+		-DCOMPILER_RT_INCLUDE_TESTS=OFF \
+		-DCOMPILER_RT_HAS_FPIC_FLAG=OFF \
+		-DCOMPILER_RT_DEFAULT_TARGET_ONLY=On \
+		-DCOMPILER_RT_OS_DIR=wasi \
+		-DCMAKE_INSTALL_PREFIX=${LLVM_HOST}/lib/clang/$(CLANG_VERSION)/
+	$(MAKE) -C build/compiler-rt-build-host install
+	touch $@ 
+
+build/compiler-rt.BUILT: build/llvm.SRC build/compiler-rt-host.BUILT
+	mkdir -p build/compiler-rt-build
+	cmake -B build/compiler-rt-build -S build/llvm-src/compiler-rt/lib/builtins \
+		-DWASM_PREFIX=${LLVM_HOST} -DCMAKE_TOOLCHAIN_FILE=${DIR}/cmake/toolchain.cmake \
+		-DCMAKE_C_FLAGS="-I${DIR} ${WASM_C}" \
+		-DCOMPILER_RT_BAREMETAL_BUILD=On \
+		-DCOMPILER_RT_INCLUDE_TESTS=OFF \
+		-DCOMPILER_RT_HAS_FPIC_FLAG=OFF \
+		-DCOMPILER_RT_DEFAULT_TARGET_ONLY=On \
+		-DCOMPILER_RT_OS_DIR=wasi \
+		-DCMAKE_INSTALL_PREFIX=${SYSROOT}/lib/clang/$(CLANG_VERSION)/
+	$(MAKE) -C build/compiler-rt-build install
+	touch $@ 
+
+build/libcxx.BUILT: build/compiler-rt.BUILT
+	mkdir -p build/libcxx-build
+	# We disable checking the C++ compiler as we are building -lc++, which is needed by the check.
+	cmake -B build/libcxx-build -S build/llvm-src/runtimes \
+		-DCMAKE_BUILD_TYPE=Release \
+		-DCMAKE_SYSROOT=$(SYSROOT) -DCMAKE_INSTALL_PREFIX="${SYSROOT}" -DDEFAULT_SYSROOT="/" \
+		-DWASM_PREFIX=${LLVM_HOST} -DCMAKE_TOOLCHAIN_FILE=${DIR}/cmake/toolchain.cmake \
+		-DCMAKE_C_FLAGS="-I${DIR} ${WASM_C}" \
+		-DCMAKE_CXX_FLAGS="-I${DIR} ${WASM_CXXFLAGS} -fno-exceptions" \
+    -DCMAKE_POSITION_INDEPENDENT_CODE=OFF \
+		-DCMAKE_C_COMPILER_WORKS=ON \
+		-DCMAKE_CXX_COMPILER_WORKS=ON \
+		-DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" \
+    -DLIBCXX_ENABLE_THREADS:BOOL=OFF \
+    -DLIBCXX_HAS_PTHREAD_API:BOOL=OFF \
+    -DLIBCXX_HAS_EXTERNAL_THREAD_API:BOOL=OFF \
+    -DLIBCXX_HAS_WIN32_THREAD_API:BOOL=OFF \
+    -DLIBCXX_ENABLE_SHARED:BOOL=OFF \
+    -DLIBCXX_ENABLE_EXCEPTIONS:BOOL=OFF \
+    -DLIBCXX_ENABLE_ABI_LINKER_SCRIPT:BOOL=OFF \
+    -DLIBCXX_CXX_ABI=libcxxabi \
+    -DLIBCXX_HAS_MUSL_LIBC:BOOL=ON \
+    -DLIBCXX_ABI_VERSION=2 \
+    -DLIBCXXABI_ENABLE_EXCEPTIONS:BOOL=OFF \
+    -DLIBCXXABI_ENABLE_SHARED:BOOL=OFF \
+    -DLIBCXXABI_SILENT_TERMINATE:BOOL=ON \
+    -DLIBCXXABI_ENABLE_THREADS:BOOL=OFF \
+    -DLIBCXXABI_HAS_PTHREAD_API:BOOL=OFF \
+    -DLIBCXXABI_HAS_EXTERNAL_THREAD_API:BOOL=OFF \
+    -DLIBCXXABI_HAS_WIN32_THREAD_API:BOOL=OFF \
+		-DLIBCXX_LIBDIR_SUFFIX=/wasm32-wasi \
+		-DLIBCXXABI_LIBDIR_SUFFIX=/wasm32-wasi
+	$(MAKE) -C build/libcxx-build install
+	touch $@ 
+
+build/llvm.BUILT: build/llvm.SRC build/libcxx.BUILT
+	cmake -B build/llvm-build -S build/llvm-src/llvm \
+		-DCMAKE_BUILD_TYPE=Release \
+		-DCMAKE_SYSROOT=$(SYSROOT) -DCMAKE_INSTALL_PREFIX="${SYSROOT}" -DDEFAULT_SYSROOT=/ \
+		-DWASM_PREFIX=${LLVM_HOST} -DCMAKE_TOOLCHAIN_FILE=${DIR}/cmake/toolchain.cmake \
+		-DCMAKE_C_FLAGS="-I${DIR} ${WASM_C}" \
+		-DCMAKE_CXX_FLAGS="-I${DIR} ${WASM_CXXFLAGS} -fno-exceptions" \
+		-DLLVM_TARGETS_TO_BUILD=WebAssembly -DLLVM_ENABLE_PROJECTS="clang;lld;clang-tools-extra" \
 		-DLLVM_ENABLE_THREADS=OFF -DLLVM_INCLUDE_BENCHMARKS=OFF \
-		-DLLVM_DEFAULT_TARGET_TRIPLE=wasm32-wasi -DCMAKE_MODULE_PATH=${DIR}/cmake \
-		-DCMAKE_CXX_FLAGS="-I${DIR} -fno-exceptions" -DLLVM_INCLUDE_TESTS=OFF \
+		-DLLVM_DEFAULT_TARGET_TRIPLE=wasm32-wasi \
+		-DLLVM_INCLUDE_TESTS=OFF -DCLANG_PLUGIN_SUPPORT=OFF \
 		-DLLVM_BUILD_LLVM_DYLIB=OFF -DLLVM_INCLUDE_EXAMPLES=OFF -DLLVM_ENABLE_PIC=OFF \
 		-DLLVM_INCLUDE_UTILS=OFF -DLLVM_BUILD_UTILS=OFF -DLLVM_ENABLE_PLUGINS=OFF \
-		-DCLANG_PLUGIN_SUPPORT=OFF \
-		-DCMAKE_EXE_LINKER_FLAGS="-Wl,-z -Wl,stack-size=1048576 -lwasishim -L${DIR}/build"
-	ninja -C build/llvm-build
-
-
-build/output/cpp: build/llvm-build
-	rm -rf "$@"
-	mkdir -p $@/root
-	cp -Lr ${WASI_SDK_PREFIX}/share/wasi-sysroot/* $@/root/
-	cp -L ${WASI_SDK_PREFIX}/lib/clang/*/lib/wasi/libclang_rt.* $@/root/lib/wasm32-wasi/
-	rm -rf $@/root/share/wasm32-wasi-threads $@/root/lib/wasm32-wasi-threads
-	cp -Lr $</lib/clang/18/include $@/root/clang-include
-	cp -Lr $</bin/clang-18 $@/clang
-	cp -Lr $</bin/lld $@/wasm-ld
-
-.PHONY:
-test: | build/output/python build/output/cpp
+		-DCMAKE_EXE_LINKER_FLAGS="${WASM_LDFLAGS}"
+	$(MAKE) -C build/llvm-build install
+	touch "$@"
+
+# Technically, this only needs wasi-libc, but errors get hidden otherwise.
+build/python.BUILT: build/wasi-libc.BUILT build/llvm.BUILT
+	rsync -a --delete cpython/ build/cpython
+	mkdir -p build/cpython/host-build
+	cd build/cpython/host-build && ../configure --prefix=${DIR}/build/cpython/install --disable-test-modules
+	$(MAKE) -C build/cpython/host-build
+	mkdir -p build/cpython/wasm-build
+	cd build/cpython/wasm-build && \
+		../configure --target wasm32-wasi --host wasm32-wasi --build=$(shell $(CC) -dumpmachine) \
+		--with-build-python=${DIR}/build/cpython/host-build/python \
+		CC=${WASM_CC} AR=$(WASM_AR) NM=${WASM_NM} CFLAGS=${WASM_CFLAGS} \
+		--prefix=${DIR}/build/sysroot --with-lto=full \
+		--enable-wasm-pthreads=no --disable-test-modules \
+		CONFIG_SITE=${DIR}/cpython-config-override
+	$(MAKE) -C build/cpython/wasm-build install
+	touch "$@"
+
+${OUTPUT}/cpp.COPIED: build/llvm.BUILT build/python.BUILT
+	mkdir -p ${OUTPUT}/cpp/{bin,lib,include}
+	rsync -avL ${SYSROOT}/bin/clang++ ${SYSROOT}/bin/wasm-ld ${OUTPUT}/cpp/bin/
+	rsync -avL ${SYSROOT}/lib/clang ${SYSROOT}/lib/wasm32-wasi ${OUTPUT}/cpp/lib/
+	rsync -avL ${SYSROOT}/include/c++ ${SYSROOT}/include/wasm32-wasi ${OUTPUT}/cpp/include/
+	touch "$@"
+
+${OUTPUT}/python.COPIED: build/llvm.BUILT build/python.BUILT
+	mkdir -p ${OUTPUT}/python/{bin,lib,include}
+	rsync -avL ${SYSROOT}/bin/python3.13.wasm ${OUTPUT}/python/bin/
+	rsync -avL ${SYSROOT}/lib/libpython3.13.a ${SYSROOT}/lib/python3.13 --exclude python3.13/config-3.13-wasm32-wasi ${OUTPUT}/python/lib/
+	rsync -avL ${SYSROOT}/include/python3.13 ${OUTPUT}/python/include/
+	touch "$@"
+
+test: test.sh ${OUTPUT}/cpp.COPIED ${OUTPUT}/python.COPIED
 	./test.sh
 
+%.tar.br: %.COPIED
+	tar c -C $* . | brotli --large_window=30 > $@
+
+${OUTPUT}.DONE: ${OUTPUT}/cpp.tar.br ${OUTPUT}/python.tar.br
+
 clean:
 	rm -rf build/ cpython/cross-build
+
+.PHONY: all test clean

cmake/Platform/WASI.cmake

@@ -1,4 +1,2 @@
 set(WASI 1)
-
-# This is a lie, but llvm needs it.
-set(UNIX 1)
+set(TARGET_SUPPORTS_SHARED_LIBS FALSE)

cmake/toolchain.cmake

@@ -0,0 +1,24 @@
+# Inspired by wasi-sdk's toolchain file
+cmake_minimum_required(VERSION 3.4.0)
+
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}")
+
+set(CMAKE_SYSTEM_NAME WASI)
+set(CMAKE_SYSTEM_VERSION 1)
+set(CMAKE_SYSTEM_PROCESSOR wasm32)
+
+set(triple wasm32-wasi)
+
+set(CMAKE_C_COMPILER ${WASM_PREFIX}/bin/clang)
+set(CMAKE_CXX_COMPILER ${WASM_PREFIX}/bin/clang++)
+set(CMAKE_ASM_COMPILER ${WASM_PREFIX}/bin/clang)
+set(CMAKE_AR ${WASM_PREFIX}/bin/llvm-ar)
+set(CMAKE_RANLIB ${WASM_PREFIX}/bin/llvm-ranlib)
+set(CMAKE_C_COMPILER_TARGET ${triple})
+set(CMAKE_CXX_COMPILER_TARGET ${triple})
+set(CMAKE_ASM_COMPILER_TARGET ${triple})
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

cpython-config-override

@@ -0,0 +1,45 @@
+# config.site override for cross compiling to wasm32-wasi platform,
+# forked from the one written by Christian Heimes <[email protected]>
+
+# cannot be detected in cross builds
+ac_cv_buggy_getaddrinfo=no
+
+# WASI has no /dev/pt*
+ac_cv_file__dev_ptmx=no
+ac_cv_file__dev_ptc=no
+
+# get/setrlimit are not supported
+ac_cv_header_sys_resource_h=no
+
+# undefined symbols / unsupported features
+ac_cv_func_eventfd=no
+
+# WASI SDK 15.0 has no pipe syscall.
+ac_cv_func_pipe=no
+
+# WASI SDK 15.0 cannot create fifos and special files.
+ac_cv_func_mkfifo=no
+ac_cv_func_mkfifoat=no
+ac_cv_func_mknod=no
+ac_cv_func_mknodat=no
+ac_cv_func_makedev=no
+
+# fdopendir() fails on SDK 15.0,
+# OSError: [Errno 28] Invalid argument: '.'
+ac_cv_func_fdopendir=no
+
+# WASI sockets are limited to operations on given socket fd and inet sockets.
+# Disable AF_UNIX and AF_PACKET support, see socketmodule.h.
+ac_cv_header_sys_un_h=no
+ac_cv_header_netpacket_packet_h=no
+
+# disable accept for WASM runtimes without sock_accept
+#ac_cv_func_accept=no
+#ac_cv_func_accept4=no
+
+# Disable int-conversion for wask-sdk as it triggers an error from version 17.
+ac_cv_disable_int_conversion=yes
+
+
+# Disable dlopen
+ac_cv_func_dlopen=no