[wasm] add asyncify based setjmp, fiber, register scan emulation

configure.ac: setup build tools and register objects

main.c: wrap main with rb_wasm_rt_start to handle asyncify unwinds

tool/m4/ruby_wasm_tools.m4: setup default command based on WASI_SDK_PATH
environment variable. checks wasm-opt which is used for asyncify.

tool/wasm-clangw wasm/wasm-opt: a clang wrapper which replaces real
wasm-opt with do-nothing wasm-opt to avoid misoptimization before
asyncify. asyncify is performed at POSTLINK, but clang linker driver
tries to run optimization by wasm-opt unconditionally. inlining pass
at wasm level breaks asyncify's assumption, so should not optimize
before POSTLIK.

wasm/GNUmakefile.in: wasm specific rules to compile objects

1 files changed, 36 insertions, 0 deletions

diff --git a/wasm/wasm-opt b/wasm/wasm-opt
new file mode 100755
index 0000000000..3ae21b8206
--- /dev/null
+++ b/wasm/wasm-opt
@@ -0,0 +1,36 @@
+#!/bin/sh
+# A fake wasm-opt, which does nothing at all
+# See also: tool/wasm-clangw
+
+set -e
+input=
+output=
+while [ $# -ne 0 ]; do
+  case "$1" in
+    -o)
+      shift
+      output=$1
+  ;;
+    -*)
+      # ignore other options
+  ;;
+    *)
+      input=$1
+  ;;
+  esac
+  shift
+done
+
+if [ -z "$input" ]; then
+  echo "missing input binary"
+  exit 1
+fi
+
+if [ -z "$output" ]; then
+  echo "missing output binary"
+  exit 1
+fi
+
+if [ "$input" != "$output" ]; then
+  cp "$input" "$output"
+fi