1 files changed, 93 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/vtable.rs b/compiler/rustc_codegen_cranelift/src/vtable.rs
new file mode 100644
index 00000000000..f04fb82de8c
--- /dev/null
+++ b/compiler/rustc_codegen_cranelift/src/vtable.rs
@@ -0,0 +1,93 @@
+//! Codegen vtables and vtable accesses.
+//!
+//! See `rustc_codegen_ssa/src/meth.rs` for reference.
+
+use crate::constant::data_id_for_alloc_id;
+use crate::prelude::*;
+
+pub(crate) fn vtable_memflags() -> MemFlags {
+    let mut flags = MemFlags::trusted(); // A vtable access is always aligned and will never trap.
+    flags.set_readonly(); // A vtable is always read-only.
+    flags
+}
+
+pub(crate) fn drop_fn_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
+    let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
+    fx.bcx.ins().load(
+        fx.pointer_type,
+        vtable_memflags(),
+        vtable,
+        (ty::COMMON_VTABLE_ENTRIES_DROPINPLACE * usize_size) as i32,
+    )
+}
+
+pub(crate) fn size_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
+    let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
+    fx.bcx.ins().load(
+        fx.pointer_type,
+        vtable_memflags(),
+        vtable,
+        (ty::COMMON_VTABLE_ENTRIES_SIZE * usize_size) as i32,
+    )
+}
+
+pub(crate) fn min_align_of_obj(fx: &mut FunctionCx<'_, '_, '_>, vtable: Value) -> Value {
+    let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
+    fx.bcx.ins().load(
+        fx.pointer_type,
+        vtable_memflags(),
+        vtable,
+        (ty::COMMON_VTABLE_ENTRIES_ALIGN * usize_size) as i32,
+    )
+}
+
+pub(crate) fn get_ptr_and_method_ref<'tcx>(
+    fx: &mut FunctionCx<'_, '_, 'tcx>,
+    arg: CValue<'tcx>,
+    idx: usize,
+) -> (Pointer, Value) {
+    let (ptr, vtable) = 'block: {
+        if let ty::Ref(_, ty, _) = arg.layout().ty.kind() {
+            if ty.is_dyn_star() {
+                let inner_layout = fx.layout_of(arg.layout().ty.builtin_deref(true).unwrap().ty);
+                let dyn_star = CPlace::for_ptr(Pointer::new(arg.load_scalar(fx)), inner_layout);
+                let ptr = dyn_star.place_field(fx, mir::Field::new(0)).to_ptr();
+                let vtable =
+                    dyn_star.place_field(fx, mir::Field::new(1)).to_cvalue(fx).load_scalar(fx);
+                break 'block (ptr, vtable);
+            }
+        }
+
+        if let Abi::ScalarPair(_, _) = arg.layout().abi {
+            let (ptr, vtable) = arg.load_scalar_pair(fx);
+            (Pointer::new(ptr), vtable)
+        } else {
+            let (ptr, vtable) = arg.try_to_ptr().unwrap();
+            (ptr, vtable.unwrap())
+        }
+    };
+
+    let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes();
+    let func_ref = fx.bcx.ins().load(
+        fx.pointer_type,
+        vtable_memflags(),
+        vtable,
+        (idx * usize_size as usize) as i32,
+    );
+    (ptr, func_ref)
+}
+
+pub(crate) fn get_vtable<'tcx>(
+    fx: &mut FunctionCx<'_, '_, 'tcx>,
+    ty: Ty<'tcx>,
+    trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
+) -> Value {
+    let alloc_id = fx.tcx.vtable_allocation((ty, trait_ref));
+    let data_id =
+        data_id_for_alloc_id(&mut fx.constants_cx, &mut *fx.module, alloc_id, Mutability::Not);
+    let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
+    if fx.clif_comments.enabled() {
+        fx.add_comment(local_data_id, format!("vtable: {:?}", alloc_id));
+    }
+    fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
+}