src/librustc_trans/monomorphize.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use abi::Abi;
  12 use common::*;
  13
  14 use rustc::hir::def_id::DefId;
  15 use rustc::middle::lang_items::DropInPlaceFnLangItem;
  16 use rustc::traits;
  17 use rustc::ty::adjustment::CustomCoerceUnsized;
  18 use rustc::ty::subst::{Kind, Subst, Substs};
  19 use rustc::ty::{self, Ty, TyCtxt};
  20
  21 use syntax::codemap::DUMMY_SP;
  22
  23 pub use rustc::ty::Instance;
  24
  25 fn fn_once_adapter_instance<'a, 'tcx>(
  26     tcx: TyCtxt<'a, 'tcx, 'tcx>,
  27     closure_did: DefId,
  28     substs: ty::ClosureSubsts<'tcx>,
  29     ) -> Instance<'tcx> {
  30     debug!("fn_once_adapter_shim({:?}, {:?})",
  31            closure_did,
  32            substs);
  33     let fn_once = tcx.lang_items().fn_once_trait().unwrap();
  34     let call_once = tcx.associated_items(fn_once)
  35         .find(|it| it.kind == ty::AssociatedKind::Method)
  36         .unwrap().def_id;
  37     let def = ty::InstanceDef::ClosureOnceShim { call_once };
  38
  39     let self_ty = tcx.mk_closure_from_closure_substs(
  40         closure_did, substs);
  41
  42     let sig = tcx.fn_sig(closure_did).subst(tcx, substs.substs);
  43     let sig = tcx.erase_late_bound_regions_and_normalize(&sig);
  44     assert_eq!(sig.inputs().len(), 1);
  45     let substs = tcx.mk_substs([
  46         Kind::from(self_ty),
  47         Kind::from(sig.inputs()[0]),
  48     ].iter().cloned());
  49
  50     debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
  51     Instance { def, substs }
  52 }
  53
  54 fn needs_fn_once_adapter_shim(actual_closure_kind: ty::ClosureKind,
  55                               trait_closure_kind: ty::ClosureKind)
  56                               -> Result<bool, ()>
  57 {
  58     match (actual_closure_kind, trait_closure_kind) {
  59         (ty::ClosureKind::Fn, ty::ClosureKind::Fn) |
  60         (ty::ClosureKind::FnMut, ty::ClosureKind::FnMut) |
  61         (ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => {
  62             // No adapter needed.
  63            Ok(false)
  64         }
  65         (ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => {
  66             // The closure fn `llfn` is a `fn(&self, ...)`.  We want a
  67             // `fn(&mut self, ...)`. In fact, at trans time, these are
  68             // basically the same thing, so we can just return llfn.
  69             Ok(false)
  70         }
  71         (ty::ClosureKind::Fn, ty::ClosureKind::FnOnce) |
  72         (ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => {
  73             // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
  74             // self, ...)`.  We want a `fn(self, ...)`. We can produce
  75             // this by doing something like:
  76             //
  77             //     fn call_once(self, ...) { call_mut(&self, ...) }
  78             //     fn call_once(mut self, ...) { call_mut(&mut self, ...) }
  79             //
  80             // These are both the same at trans time.
  81             Ok(true)
  82         }
  83         _ => Err(()),
  84     }
  85 }
  86
  87 pub fn resolve_closure<'a, 'tcx> (
  88     scx: &SharedCrateContext<'a, 'tcx>,
  89     def_id: DefId,
  90     substs: ty::ClosureSubsts<'tcx>,
  91     requested_kind: ty::ClosureKind)
  92     -> Instance<'tcx>
  93 {
  94     let actual_kind = scx.tcx().closure_kind(def_id);
  95
  96     match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
  97         Ok(true) => fn_once_adapter_instance(scx.tcx(), def_id, substs),
  98         _ => Instance::new(def_id, substs.substs)
  99     }
 100 }
 101
 102 fn resolve_associated_item<'a, 'tcx>(
 103     scx: &SharedCrateContext<'a, 'tcx>,
 104     trait_item: &ty::AssociatedItem,
 105     trait_id: DefId,
 106     rcvr_substs: &'tcx Substs<'tcx>
 107 ) -> Instance<'tcx> {
 108     let tcx = scx.tcx();
 109     let def_id = trait_item.def_id;
 110     debug!("resolve_associated_item(trait_item={:?}, \
 111                                     trait_id={:?}, \
 112                                     rcvr_substs={:?})",
 113            def_id, trait_id, rcvr_substs);
 114
 115     let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
 116     let vtbl = tcx.trans_fulfill_obligation(DUMMY_SP, ty::Binder(trait_ref));
 117
 118     // Now that we know which impl is being used, we can dispatch to
 119     // the actual function:
 120     match vtbl {
 121         traits::VtableImpl(impl_data) => {
 122             let (def_id, substs) = traits::find_associated_item(
 123                 tcx, trait_item, rcvr_substs, &impl_data);
 124             let substs = tcx.erase_regions(&substs);
 125             ty::Instance::new(def_id, substs)
 126         }
 127         traits::VtableGenerator(closure_data) => {
 128             Instance {
 129                 def: ty::InstanceDef::Item(closure_data.closure_def_id),
 130                 substs: closure_data.substs.substs
 131             }
 132         }
 133         traits::VtableClosure(closure_data) => {
 134             let trait_closure_kind = tcx.lang_items().fn_trait_kind(trait_id).unwrap();
 135             resolve_closure(scx, closure_data.closure_def_id, closure_data.substs,
 136                             trait_closure_kind)
 137         }
 138         traits::VtableFnPointer(ref data) => {
 139             Instance {
 140                 def: ty::InstanceDef::FnPtrShim(trait_item.def_id, data.fn_ty),
 141                 substs: rcvr_substs
 142             }
 143         }
 144         traits::VtableObject(ref data) => {
 145             let index = tcx.get_vtable_index_of_object_method(data, def_id);
 146             Instance {
 147                 def: ty::InstanceDef::Virtual(def_id, index),
 148                 substs: rcvr_substs
 149             }
 150         }
 151         traits::VtableBuiltin(..) if Some(trait_id) == tcx.lang_items().clone_trait() => {
 152             Instance {
 153                 def: ty::InstanceDef::CloneShim(def_id, trait_ref.self_ty()),
 154                 substs: rcvr_substs
 155             }
 156         }
 157         _ => {
 158             bug!("static call to invalid vtable: {:?}", vtbl)
 159         }
 160     }
 161 }
 162
 163 /// The point where linking happens. Resolve a (def_id, substs)
 164 /// pair to an instance.
 165 pub fn resolve<'a, 'tcx>(
 166     scx: &SharedCrateContext<'a, 'tcx>,
 167     def_id: DefId,
 168     substs: &'tcx Substs<'tcx>
 169 ) -> Instance<'tcx> {
 170     debug!("resolve(def_id={:?}, substs={:?})",
 171            def_id, substs);
 172     let result = if let Some(trait_def_id) = scx.tcx().trait_of_item(def_id) {
 173         debug!(" => associated item, attempting to find impl");
 174         let item = scx.tcx().associated_item(def_id);
 175         resolve_associated_item(scx, &item, trait_def_id, substs)
 176     } else {
 177         let item_type = def_ty(scx, def_id, substs);
 178         let def = match item_type.sty {
 179             ty::TyFnDef(..) if {
 180                     let f = item_type.fn_sig(scx.tcx());
 181                     f.abi() == Abi::RustIntrinsic ||
 182                     f.abi() == Abi::PlatformIntrinsic
 183                 } =>
 184             {
 185                 debug!(" => intrinsic");
 186                 ty::InstanceDef::Intrinsic(def_id)
 187             }
 188             _ => {
 189                 if Some(def_id) == scx.tcx().lang_items().drop_in_place_fn() {
 190                     let ty = substs.type_at(0);
 191                     if scx.type_needs_drop(ty) {
 192                         debug!(" => nontrivial drop glue");
 193                         ty::InstanceDef::DropGlue(def_id, Some(ty))
 194                     } else {
 195                         debug!(" => trivial drop glue");
 196                         ty::InstanceDef::DropGlue(def_id, None)
 197                     }
 198                 } else {
 199                     debug!(" => free item");
 200                     ty::InstanceDef::Item(def_id)
 201                 }
 202             }
 203         };
 204         Instance { def, substs }
 205     };
 206     debug!("resolve(def_id={:?}, substs={:?}) = {}",
 207            def_id, substs, result);
 208     result
 209 }
 210
 211 pub fn resolve_drop_in_place<'a, 'tcx>(
 212     scx: &SharedCrateContext<'a, 'tcx>,
 213     ty: Ty<'tcx>)
 214     -> ty::Instance<'tcx>
 215 {
 216     let def_id = scx.tcx().require_lang_item(DropInPlaceFnLangItem);
 217     let substs = scx.tcx().intern_substs(&[Kind::from(ty)]);
 218     resolve(scx, def_id, substs)
 219 }
 220
 221 pub fn custom_coerce_unsize_info<'scx, 'tcx>(scx: &SharedCrateContext<'scx, 'tcx>,
 222                                              source_ty: Ty<'tcx>,
 223                                              target_ty: Ty<'tcx>)
 224                                              -> CustomCoerceUnsized {
 225     let trait_ref = ty::Binder(ty::TraitRef {
 226         def_id: scx.tcx().lang_items().coerce_unsized_trait().unwrap(),
 227         substs: scx.tcx().mk_substs_trait(source_ty, &[target_ty])
 228     });
 229
 230     match scx.tcx().trans_fulfill_obligation(DUMMY_SP, trait_ref) {
 231         traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => {
 232             scx.tcx().coerce_unsized_info(impl_def_id).custom_kind.unwrap()
 233         }
 234         vtable => {
 235             bug!("invalid CoerceUnsized vtable: {:?}", vtable);
 236         }
 237     }
 238 }
 239
 240 /// Returns the normalized type of a struct field
 241 pub fn field_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 242                           param_substs: &Substs<'tcx>,
 243                           f: &'tcx ty::FieldDef)
 244                           -> Ty<'tcx>
 245 {
 246     tcx.normalize_associated_type(&f.ty(tcx, param_substs))
 247 }
 248