ports/unix: Add build-wasi.sh script.

For now, mainly for documentation purpose.
As you can see, this involves a lot of experimental things.

Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>

ports/unix/build-wasi.sh

@@ -0,0 +1,70 @@
+#! /bin/sh
+
+# prerequisites
+#
+# https://github.com/WebAssembly/wasi-libc/pull/467
+# https://github.com/WebAssembly/wasi-libc/pull/473
+# https://github.com/WebAssembly/binaryen/pull/6294
+# https://github.com/WebAssembly/binaryen/pull/6259
+#
+# WASI_SDK: wasi-sdk 21.0
+# WASM_OPT: binaryen wasm-opt built with the above patches
+# WASI_SYSROOT: wasi-libc built with the above patches
+# ../../../micropython-ulab: check out https://github.com/v923z/micropython-ulab
+
+WASI_SDK=${WASI_SDK:-/opt/wasi-sdk-21.0}
+WASI_SYSROOT=${WASI_SYSROOT:-${HOME}/git/wasi-libc/sysroot}
+BINARYEN_BIN=${BINARYEN_BIN:-${HOME}/git/wasm/binaryen/b/bin}
+WASM_OPT=${WASM_OPT:-${BINARYEN_BIN}/wasm-opt}
+
+# MICROPY_PY_THREAD: GC uses signals, which is not available on wasi.
+
+# the following things seem building well. i disabled them just because
+# i was not intererested in them.
+# MICROPY_VFS_FAT
+# MICROPY_VFS_LFS1
+# MICROPY_VFS_LFS2
+
+# micropython-ulab was added just as an example of user C module.
+# you can remove it if you don't use it.
+
+CFLAGS="-D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL -D_WASI_EMULATED_MMAN -mllvm -wasm-enable-sjlj" \
+LDFLAGS="-lwasi-emulated-process-clocks -lwasi-emulated-signal -lwasi-emulated-mman" \
+make \
+CC="${WASI_SDK}/bin/clang --sysroot=${WASI_SYSROOT}" \
+LD="${WASI_SDK}/bin/wasm-ld" \
+STRIP="${WASI_SDK}/bin/strip" \
+SIZE="${WASI_SDK}/bin/size" \
+UNAME_S=wasi \
+MICROPY_PY_FFI=0 \
+MICROPY_PY_THREAD=0 \
+MICROPY_PY_SOCKET=0 \
+MICROPY_PY_SSL=0 \
+MICROPY_PY_BTREE=0 \
+MICROPY_PY_TERMIOS=0 \
+MICROPY_USE_READLINE=0 \
+MICROPY_VFS_FAT=0 \
+MICROPY_VFS_LFS1=0 \
+MICROPY_VFS_LFS2=0 \
+USER_C_MODULES=../../../micropython-ulab \
+"$@"
+
+PROG=build-standard/micropython
+
+# We doesn't have a way to scan GC roots like WASM locals.
+# Hopefully --spill-pointers can workaround it.
+${WASM_OPT} \
+--spill-pointers \
+-o ${PROG}.spilled ${PROG}
+
+# LLVM still uses the older version of EH proposal.
+# Convert to the latest version of EH proposal.
+${WASM_OPT} \
+--translate-to-new-eh --enable-exception-handling \
+-o ${PROG}.spilled.neweh ${PROG}.spilled
+
+# now you can run it with EH-enabled runtimes.
+# eg.  (using the latest EH)
+# toywasm --wasi build-standard/micropython.spilled.neweh
+# eg.  (using the old EH)
+# iwasm build-standard/micropython.spilled