Refactor Metadata (#76)

* update object model members
* update the restructured metadata module
* suggest more metadata access inlining

Author: Javad Amiri

mmtk/Cargo.toml

@@ -20,7 +20,7 @@ lazy_static = "1.1"
 # - change branch
 # - change repo name
 # But other changes including adding/removing whitespaces in commented lines may break the CI.
-mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "ad824527bc7fa87dfba66cc2cd8745ad1c331b9f" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "a288b40997e148817d5b9fed7d8b6039f8e944c7" }
 # Uncomment the following to build locally
 # mmtk = { path = "../repos/mmtk-core" }
 

mmtk/src/lib.rs

@@ -28,6 +28,7 @@ pub mod object_model;
 mod object_scanning;
 pub mod reference_glue;
 pub mod scanning;
+pub(crate) mod vm_metadata;
 
 #[repr(C)]
 pub struct NewBuffer {

mmtk/src/object_model.rs

@@ -1,5 +1,8 @@
+use std::sync::atomic::Ordering;
+
 use super::UPCALLS;
-use crate::OpenJDK;
+use crate::{vm_metadata, OpenJDK};
+use mmtk::util::metadata::{header_metadata::HeaderMetadataSpec, MetadataSpec};
 use mmtk::util::{Address, ObjectReference};
 use mmtk::vm::*;
 use mmtk::AllocationSemantics;
@@ -8,10 +11,76 @@ use mmtk::CopyContext;
 pub struct VMObjectModel {}
 
 impl ObjectModel<OpenJDK> for VMObjectModel {
-    #[cfg(target_pointer_width = "64")]
-    const GC_BYTE_OFFSET: isize = 7;
-    #[cfg(target_pointer_width = "32")]
-    const GC_BYTE_OFFSET: isize = 0;
+    // For now we use the default const from mmtk-core
+    const GLOBAL_LOG_BIT_SPEC: MetadataSpec = vm_metadata::LOGGING_SIDE_METADATA_SPEC;
+
+    const LOCAL_FORWARDING_POINTER_SPEC: MetadataSpec =
+        vm_metadata::FORWARDING_POINTER_METADATA_SPEC;
+    const LOCAL_FORWARDING_BITS_SPEC: MetadataSpec = vm_metadata::FORWARDING_BITS_METADATA_SPEC;
+    const LOCAL_MARK_BIT_SPEC: MetadataSpec = vm_metadata::MARKING_METADATA_SPEC;
+    const LOCAL_LOS_MARK_NURSERY_SPEC: MetadataSpec = vm_metadata::LOS_METADATA_SPEC;
+
+    #[inline(always)]
+    fn load_metadata(
+        metadata_spec: HeaderMetadataSpec,
+        object: ObjectReference,
+        mask: Option<usize>,
+        atomic_ordering: Option<Ordering>,
+    ) -> usize {
+        vm_metadata::load_metadata(metadata_spec, object, mask, atomic_ordering)
+    }
+
+    #[inline(always)]
+    fn store_metadata(
+        metadata_spec: HeaderMetadataSpec,
+        object: ObjectReference,
+        val: usize,
+        mask: Option<usize>,
+        atomic_ordering: Option<Ordering>,
+    ) {
+        vm_metadata::store_metadata(metadata_spec, object, val, mask, atomic_ordering);
+    }
+
+    #[inline(always)]
+    fn compare_exchange_metadata(
+        metadata_spec: HeaderMetadataSpec,
+        object: ObjectReference,
+        old_val: usize,
+        new_val: usize,
+        mask: Option<usize>,
+        success_order: Ordering,
+        failure_order: Ordering,
+    ) -> bool {
+        vm_metadata::compare_exchange_metadata(
+            metadata_spec,
+            object,
+            old_val,
+            new_val,
+            mask,
+            success_order,
+            failure_order,
+        )
+    }
+
+    #[inline(always)]
+    fn fetch_add_metadata(
+        metadata_spec: HeaderMetadataSpec,
+        object: ObjectReference,
+        val: usize,
+        order: Ordering,
+    ) -> usize {
+        vm_metadata::fetch_add_metadata(metadata_spec, object, val, order)
+    }
+
+    #[inline(always)]
+    fn fetch_sub_metadata(
+        metadata_spec: HeaderMetadataSpec,
+        object: ObjectReference,
+        val: usize,
+        order: Ordering,
+    ) -> usize {
+        vm_metadata::fetch_sub_metadata(metadata_spec, object, val, order)
+    }
 
     #[inline]
     fn copy(

mmtk/src/vm_metadata/constants.rs

@@ -0,0 +1,61 @@
+pub(super) use mmtk::util::constants::LOG_BITS_IN_WORD;
+use mmtk::util::metadata::header_metadata::HeaderMetadataSpec;
+#[cfg(target_pointer_width = "32")]
+use mmtk::util::metadata::metadata_bytes_per_chunk;
+use mmtk::util::metadata::side_metadata::{SideMetadataSpec, GLOBAL_SIDE_METADATA_BASE_ADDRESS};
+use mmtk::util::metadata::MetadataSpec;
+
+#[cfg(target_pointer_width = "64")]
+pub(crate) const FORWARDING_BITS_OFFSET: usize = 56;
+#[cfg(target_pointer_width = "32")]
+pub(crate) const FORWARDING_BITS_OFFSET: usize = 0;
+
+pub(crate) const FORWARDING_POINTER_OFFSET: usize = 0;
+
+// Global MetadataSpecs - Start
+
+/// Global logging bit metadata spec
+/// 1 bit per object
+pub(crate) const LOGGING_SIDE_METADATA_SPEC: MetadataSpec =
+    MetadataSpec::OnSide(SideMetadataSpec {
+        is_global: true,
+        offset: GLOBAL_SIDE_METADATA_BASE_ADDRESS.as_usize(),
+        log_num_of_bits: 0,
+        log_min_obj_size: 3,
+    });
+
+// Global MetadataSpecs - End
+
+// PolicySpecific MetadataSpecs - Start
+
+/// PolicySpecific forwarding pointer metadata spec
+/// 1 word per object
+pub(crate) const FORWARDING_POINTER_METADATA_SPEC: MetadataSpec =
+    MetadataSpec::InHeader(HeaderMetadataSpec {
+        bit_offset: FORWARDING_POINTER_OFFSET as isize,
+        num_of_bits: 1 << LOG_BITS_IN_WORD,
+    });
+
+/// PolicySpecific object forwarding status metadata spec
+/// 2 bits per object
+pub(crate) const FORWARDING_BITS_METADATA_SPEC: MetadataSpec =
+    MetadataSpec::InHeader(HeaderMetadataSpec {
+        bit_offset: FORWARDING_BITS_OFFSET as isize,
+        num_of_bits: 2,
+    });
+
+/// PolicySpecific mark bit metadata spec
+/// 1 bit per object
+pub(crate) const MARKING_METADATA_SPEC: MetadataSpec = MetadataSpec::InHeader(HeaderMetadataSpec {
+    bit_offset: FORWARDING_BITS_OFFSET as isize,
+    num_of_bits: 1,
+});
+
+/// PolicySpecific mark-and-nursery bits metadata spec
+/// 2-bits per object
+pub(crate) const LOS_METADATA_SPEC: MetadataSpec = MetadataSpec::InHeader(HeaderMetadataSpec {
+    bit_offset: FORWARDING_BITS_OFFSET as isize,
+    num_of_bits: 2,
+});
+
+// PolicySpecific MetadataSpecs - End

mmtk/src/vm_metadata/global.rs

@@ -0,0 +1,75 @@
+use mmtk::util::{metadata as mmtk_meta, ObjectReference};
+use std::sync::atomic::Ordering;
+
+/// This function implements the `load_metadata` method from the `ObjectModel` trait.
+#[inline(always)]
+pub(crate) fn load_metadata(
+    metadata_spec: mmtk_meta::header_metadata::HeaderMetadataSpec,
+    object: ObjectReference,
+    optional_mask: Option<usize>,
+    atomic_ordering: Option<Ordering>,
+) -> usize {
+    mmtk_meta::header_metadata::load_metadata(metadata_spec, object, optional_mask, atomic_ordering)
+}
+
+/// This function implements the `store_metadata` method from the `ObjectModel` trait.
+#[inline(always)]
+pub(crate) fn store_metadata(
+    metadata_spec: mmtk_meta::header_metadata::HeaderMetadataSpec,
+    object: ObjectReference,
+    val: usize,
+    optional_mask: Option<usize>,
+    atomic_ordering: Option<Ordering>,
+) {
+    mmtk_meta::header_metadata::store_metadata(
+        metadata_spec,
+        object,
+        val,
+        optional_mask,
+        atomic_ordering,
+    )
+}
+
+/// This function implements the `compare_exchange_metadata` method from the `ObjectModel` trait.
+#[inline(always)]
+pub(crate) fn compare_exchange_metadata(
+    metadata_spec: mmtk_meta::header_metadata::HeaderMetadataSpec,
+    object: ObjectReference,
+    old_metadata: usize,
+    new_metadata: usize,
+    optional_mask: Option<usize>,
+    success_order: Ordering,
+    failure_order: Ordering,
+) -> bool {
+    mmtk_meta::header_metadata::compare_exchange_metadata(
+        metadata_spec,
+        object,
+        old_metadata,
+        new_metadata,
+        optional_mask,
+        success_order,
+        failure_order,
+    )
+}
+
+/// This function implements the `fetch_add_metadata` method from the `ObjectModel` trait.
+#[inline(always)]
+pub(crate) fn fetch_add_metadata(
+    metadata_spec: mmtk_meta::header_metadata::HeaderMetadataSpec,
+    object: ObjectReference,
+    val: usize,
+    order: Ordering,
+) -> usize {
+    mmtk_meta::header_metadata::fetch_add_metadata(metadata_spec, object, val, order)
+}
+
+/// This function implements the `fetch_sub_metadata` method from the `ObjectModel` trait.
+#[inline(always)]
+pub(crate) fn fetch_sub_metadata(
+    metadata_spec: mmtk_meta::header_metadata::HeaderMetadataSpec,
+    object: ObjectReference,
+    val: usize,
+    order: Ordering,
+) -> usize {
+    mmtk_meta::header_metadata::fetch_sub_metadata(metadata_spec, object, val, order)
+}

mmtk/src/vm_metadata/mod.rs

@@ -0,0 +1,5 @@
+mod constants;
+mod global;
+
+pub(crate) use self::constants::*;
+pub(crate) use self::global::*;