ruby.h: RB_GC_GUARD stronger than gcc7

* include/ruby/ruby.h (RB_GC_GUARD): prevent guarded pointer from
  optimization by using as an input to inline asm.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57619 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 7 insertions, 3 deletions

diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 6144c67234..d0651f40ac 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -536,7 +536,11 @@ static inline int rb_type(VALUE obj);
 
 #ifdef __GNUC__
 #define RB_GC_GUARD(v) \
-    (*__extension__ ({volatile VALUE *rb_gc_guarded_ptr = &(v); rb_gc_guarded_ptr;}))
+    (*__extension__ ({ \
+	volatile VALUE *rb_gc_guarded_ptr = &(v); \
+	__asm__("### RB_GC_GUARD("#v")" : : "m"(rb_gc_guarded_ptr)); \
+	rb_gc_guarded_ptr; \
+    }))
 #elif defined _MSC_VER
 #pragma optimize("", off)
 static inline volatile VALUE *rb_gc_guarded_ptr(volatile VALUE *ptr) {return ptr;}
diff --git a/marshal.c b/marshal.c
index d628daa4de..a9926acf56 100644
--- a/marshal.c
+++ b/marshal.c
@@ -1024,7 +1024,7 @@ VALUE
 rb_marshal_dump_limited(VALUE obj, VALUE port, int limit)
 {
     struct dump_arg *arg;
-    volatile VALUE wrapper; /* used to avoid memory leak in case of exception */
+    VALUE wrapper; /* used to avoid memory leak in case of exception */
 
     wrapper = TypedData_Make_Struct(rb_cData, struct dump_arg, &dump_arg_data, arg);
     arg->dest = 0;
@@ -2038,7 +2038,7 @@ rb_marshal_load_with_proc(VALUE port, VALUE proc)
 {
     int major, minor, infection = 0;
     VALUE v;
-    volatile VALUE wrapper; /* used to avoid memory leak in case of exception */
+    VALUE wrapper; /* used to avoid memory leak in case of exception */
     struct load_arg *arg;
 
     v = rb_check_string_type(port);