105 lines
3.4 KiB
Rust
105 lines
3.4 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use llvm::ValueRef;
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use rustc::traits;
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use callee;
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use common::*;
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use builder::Builder;
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use consts;
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use machine;
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use monomorphize;
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use type_::Type;
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use value::Value;
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use rustc::ty;
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#[derive(Copy, Clone, Debug)]
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pub struct VirtualIndex(usize);
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pub const DESTRUCTOR: VirtualIndex = VirtualIndex(0);
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pub const SIZE: VirtualIndex = VirtualIndex(1);
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pub const ALIGN: VirtualIndex = VirtualIndex(2);
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impl<'a, 'tcx> VirtualIndex {
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pub fn from_index(index: usize) -> Self {
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VirtualIndex(index + 3)
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}
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pub fn get_fn(self, bcx: &Builder<'a, 'tcx>, llvtable: ValueRef) -> ValueRef {
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// Load the data pointer from the object.
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debug!("get_fn({:?}, {:?})", Value(llvtable), self);
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let ptr = bcx.load_nonnull(bcx.gepi(llvtable, &[self.0]), None);
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// Vtable loads are invariant
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bcx.set_invariant_load(ptr);
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ptr
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}
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pub fn get_usize(self, bcx: &Builder<'a, 'tcx>, llvtable: ValueRef) -> ValueRef {
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// Load the data pointer from the object.
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debug!("get_int({:?}, {:?})", Value(llvtable), self);
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let llvtable = bcx.pointercast(llvtable, Type::int(bcx.ccx).ptr_to());
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let ptr = bcx.load(bcx.gepi(llvtable, &[self.0]), None);
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// Vtable loads are invariant
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bcx.set_invariant_load(ptr);
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ptr
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}
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}
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/// Creates a dynamic vtable for the given type and vtable origin.
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/// This is used only for objects.
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///
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/// The vtables are cached instead of created on every call.
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///
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/// The `trait_ref` encodes the erased self type. Hence if we are
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/// making an object `Foo<Trait>` from a value of type `Foo<T>`, then
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/// `trait_ref` would map `T:Trait`.
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pub fn get_vtable<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
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ty: ty::Ty<'tcx>,
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trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>)
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-> ValueRef
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{
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let tcx = ccx.tcx();
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debug!("get_vtable(ty={:?}, trait_ref={:?})", ty, trait_ref);
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// Check the cache.
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if let Some(&val) = ccx.vtables().borrow().get(&(ty, trait_ref)) {
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return val;
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}
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// Not in the cache. Build it.
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let nullptr = C_null(Type::nil(ccx).ptr_to());
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let mut components: Vec<_> = [
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callee::get_fn(ccx, monomorphize::resolve_drop_in_place(ccx.shared(), ty)),
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C_uint(ccx, ccx.size_of(ty)),
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C_uint(ccx, ccx.align_of(ty))
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].iter().cloned().collect();
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if let Some(trait_ref) = trait_ref {
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let trait_ref = trait_ref.with_self_ty(tcx, ty);
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let methods = traits::get_vtable_methods(tcx, trait_ref).map(|opt_mth| {
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opt_mth.map_or(nullptr, |(def_id, substs)| {
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callee::resolve_and_get_fn(ccx, def_id, substs)
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})
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});
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components.extend(methods);
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}
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let vtable_const = C_struct(ccx, &components, false);
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let align = machine::llalign_of_pref(ccx, val_ty(vtable_const));
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let vtable = consts::addr_of(ccx, vtable_const, align, "vtable");
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ccx.vtables().borrow_mut().insert((ty, trait_ref), vtable);
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vtable
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}
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