[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, 26 insertions, 0 deletions

diff --git a/wasm/machine.h b/wasm/machine.h
new file mode 100644
index 0000000000..4cf7228684
--- /dev/null
+++ b/wasm/machine.h
@@ -0,0 +1,26 @@
+#ifndef RB_WASM_SUPPORT_MACHINE_H
+#define RB_WASM_SUPPORT_MACHINE_H
+
+// Function pointer used as scan callbacks
+typedef void (*rb_wasm_scan_func)(void*, void*);
+
+// Scan WebAssembly locals in the all call stack (like registers) spilled by Asyncify
+// Used by conservative GC
+void rb_wasm_scan_locals(rb_wasm_scan_func scan);
+
+// Scan userland C-stack memory space in WebAssembly. Used by conservative GC
+#define rb_wasm_scan_stack(scan) _rb_wasm_scan_stack((scan), rb_wasm_get_stack_pointer())
+void _rb_wasm_scan_stack(rb_wasm_scan_func scan, void *current);
+
+
+// Get the current stack pointer
+void *rb_wasm_get_stack_pointer(void);
+
+// Set the current stack pointer
+void rb_wasm_set_stack_pointer(void *sp);
+
+// Returns the Asyncify buffer of next rewinding if unwound for spilling locals.
+// Used by the top level Asyncify handling in wasm/runtime.c
+void *rb_wasm_handle_scan_unwind(void);
+
+#endif