Manually inline rb_tr_gc_guard() in its only usage

Author: eregon

lib/cext/include/ruby/ruby.h

@@ -562,7 +562,8 @@ bool RB_TYPE_P(VALUE value, int type);
 #ifdef __GNUC__
 #define RB_GC_GUARD(v) \
     (*__extension__ ({ \
-	volatile VALUE *rb_gc_guarded_ptr = rb_tr_gc_guard(&v);   \
+	polyglot_invoke(RUBY_CEXT, "rb_tr_gc_guard", v); \
+	volatile VALUE *rb_gc_guarded_ptr = &v; \
 	rb_gc_guarded_ptr; \
     }))
 #elif defined _MSC_VER

lib/cext/include/truffleruby/truffleruby-pre.h

@@ -52,13 +52,6 @@ extern void* (*rb_tr_unwrap)(VALUE obj);
 extern VALUE (*rb_tr_wrap)(void *obj);
 extern VALUE (*rb_tr_longwrap)(long obj);
 
-// Needed for GC guarding
-
-ALWAYS_INLINE(static VALUE* rb_tr_gc_guard(VALUE *ptr));
-static inline VALUE* rb_tr_gc_guard(VALUE *ptr) {
-  polyglot_invoke(RUBY_CEXT, "rb_tr_gc_guard", *ptr);
-  return ptr;
-}
 
 #define RB_NIL_P(value) ((int)polyglot_as_boolean(polyglot_invoke(rb_tr_cext, "RB_NIL_P", value)))