use a more efficient vtable representation

[TyDesc, ... methods] -> [destructor, ... methods]

Author: thestinger

src/librustc/middle/trans/glue.rs

@@ -367,17 +367,9 @@ fn make_drop_glue<'a>(bcx: &'a Block<'a>, v0: ValueRef, t: ty::t) -> &'a Block<'
             let lluniquevalue = GEPi(bcx, v0, [0, abi::trt_field_box]);
             // Only drop the value when it is non-null
             with_cond(bcx, IsNotNull(bcx, Load(bcx, lluniquevalue)), |bcx| {
-                let llvtable = Load(bcx, GEPi(bcx, v0, [0, abi::trt_field_vtable]));
-
-                // Cast the vtable to a pointer to a pointer to a tydesc.
-                let llvtable = PointerCast(bcx, llvtable,
-                                           ccx.tydesc_type.ptr_to().ptr_to());
-                let lltydesc = Load(bcx, llvtable);
-                call_tydesc_glue_full(bcx,
-                                      lluniquevalue,
-                                      lltydesc,
-                                      abi::tydesc_field_drop_glue,
-                                      None);
+                let lldtor_ptr = Load(bcx, GEPi(bcx, v0, [0, abi::trt_field_vtable]));
+                let lldtor = Load(bcx, lldtor_ptr);
+                Call(bcx, lldtor, [PointerCast(bcx, lluniquevalue, Type::i8p())], []);
                 bcx
             })
         }

src/librustc/middle/trans/meth.rs

@@ -498,7 +498,7 @@ pub fn make_vtable(ccx: &CrateContext,
     unsafe {
         let _icx = push_ctxt("meth::make_vtable");
 
-        let mut components = ~[ tydesc.tydesc ];
+        let mut components = ~[tydesc.drop_glue.get().unwrap()];
         for &ptr in ptrs.iter() {
             components.push(ptr)
         }

src/librustc/middle/trans/type_.rs

@@ -180,7 +180,7 @@ impl Type {
     }
 
     pub fn vtable() -> Type {
-        Type::array(&Type::i8().ptr_to(), 1)
+        Type::array(&Type::i8p().ptr_to(), 1)
     }
 
     pub fn generic_glue_fn(cx: &CrateContext) -> Type {
@@ -246,13 +246,13 @@ impl Type {
     }
 
     pub fn opaque_trait(ctx: &CrateContext, store: ty::TraitStore) -> Type {
-        let tydesc_ptr = ctx.tydesc_type.ptr_to();
+        let vtable = Type::glue_fn(Type::i8p()).ptr_to().ptr_to();
         let box_ty = match store {
             ty::BoxTraitStore => Type::at_box(ctx, Type::i8()),
             ty::UniqTraitStore => Type::i8(),
             ty::RegionTraitStore(..) => Type::i8()
         };
-        Type::struct_([tydesc_ptr, box_ty.ptr_to()], false)
+        Type::struct_([vtable, box_ty.ptr_to()], false)
     }
 
     pub fn kind(&self) -> TypeKind {