[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, 10 insertions, 1 deletions

diff --git a/main.c b/main.c
index d81cfce879..03dd5a4443 100644
--- a/main.c
+++ b/main.c
@@ -31,7 +31,7 @@
 #endif
 
 int
-main(int argc, char **argv)
+rb_main(int argc, char **argv)
 {
 #ifdef RUBY_DEBUG_ENV
     ruby_set_debug_option(getenv("RUBY_DEBUG"));
@@ -47,3 +47,12 @@ main(int argc, char **argv)
 	return ruby_run_node(ruby_options(argc, argv));
     }
 }
+
+int main(int argc, char **argv) {
+#if defined(__wasm__) && !defined(__EMSCRIPTEN__)
+  int rb_wasm_rt_start(int (main)(int argc, char **argv), int argc, char **argv);
+  return rb_wasm_rt_start(rb_main, argc, argv);
+#else
+  return rb_main(argc, argv);
+#endif
+}