ZJIT: Add a VALUE#write_barrier helper method to deduplicate logic

Author: eregon

zjit/src/cruby.rs

@@ -681,6 +681,14 @@ impl VALUE {
         let k: isize = item.wrapping_add(item.wrapping_add(1));
         VALUE(k as usize)
     }
+
+    /// Call the write barrier after separately writing val to self.
+    pub fn write_barrier(self, val: VALUE) {
+        // rb_gc_writebarrier() asserts it is not called with a special constant
+        if !val.special_const_p() {
+            unsafe { rb_gc_writebarrier(self, val) };
+        }
+    }
 }
 
 pub type IseqParameters = rb_iseq_constant_body_rb_iseq_parameters;

zjit/src/gc.rs

@@ -183,9 +183,7 @@ pub fn append_gc_offsets(iseq: IseqPtr, mut version: IseqVersionRef, offsets: &V
         let value_ptr = value_ptr as *const VALUE;
         unsafe {
             let object = value_ptr.read_unaligned();
-            if !object.special_const_p() {
-                rb_gc_writebarrier(iseq.into(), object);
-            }
+            VALUE::from(iseq).write_barrier(object);
         }
     }
 }

zjit/src/profile.rs

@@ -124,9 +124,7 @@ fn profile_operands(profiler: &mut Profiler, profile: &mut IseqProfile, n: usize
         // TODO(max): Handle GC-hidden classes like Array, Hash, etc and make them look normal or
         // drop them or something
         let ty = ProfiledType::new(obj);
-        if !ty.class().special_const_p() {
-            unsafe { rb_gc_writebarrier(profiler.iseq.into(), ty.class()) };
-        }
+        VALUE::from(profiler.iseq).write_barrier(ty.class());
         profile_type.observe(ty);
     }
 }
@@ -140,9 +138,7 @@ fn profile_self(profiler: &mut Profiler, profile: &mut IseqProfile) {
     // TODO(max): Handle GC-hidden classes like Array, Hash, etc and make them look normal or
     // drop them or something
     let ty = ProfiledType::new(obj);
-    if !ty.class().special_const_p() {
-        unsafe { rb_gc_writebarrier(profiler.iseq.into(), ty.class()) };
-    }
+    VALUE::from(profiler.iseq).write_barrier(ty.class());
     types[0].observe(ty);
 }
 
@@ -153,9 +149,7 @@ fn profile_block_handler(profiler: &mut Profiler, profile: &mut IseqProfile) {
     }
     let obj = profiler.peek_at_block_handler();
     let ty = ProfiledType::object(obj);
-    if !ty.class().special_const_p() {
-        unsafe { rb_gc_writebarrier(profiler.iseq.into(), ty.class()) };
-    }
+    VALUE::from(profiler.iseq).write_barrier(ty.class());
     types[0].observe(ty);
 }