Introduce Ractor mechanism for parallel execution

This commit introduces Ractor mechanism to run Ruby program in
parallel. See doc/ractor.md for more details about Ractor.
See ticket [Feature #17100] to see the implementation details
and discussions.

[Feature #17100]

This commit does not complete the implementation. You can find
many bugs on using Ractor. Also the specification will be changed
so that this feature is experimental. You will see a warning when
you make the first Ractor with `Ractor.new`.

I hope this feature can help programmers from thread-safety issues.

1 files changed, 7 insertions, 0 deletions

diff --git a/gc.h b/gc.h
index 47a4ca19a0..5d113cafce 100644
--- a/gc.h
+++ b/gc.h
@@ -16,6 +16,13 @@ NOINLINE(void rb_gc_set_stack_end(VALUE **stack_end_p));
 #define USE_CONSERVATIVE_STACK_END
 #endif
 
+#define RB_GC_SAVE_MACHINE_CONTEXT(th)				\
+    do {							\
+	FLUSH_REGISTER_WINDOWS;					\
+	setjmp((th)->ec->machine.regs);				\
+	SET_MACHINE_STACK_END(&(th)->ec->machine.stack_end);	\
+    } while (0)
+
 /* for GC debug */
 
 #ifndef RUBY_MARK_FREE_DEBUG