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 use glue;
  14
  15 use rustc::hir::def_id::DefId;
  16 use rustc::middle::lang_items::DropInPlaceFnLangItem;
  17 use rustc::traits;
  18 use rustc::ty::adjustment::CustomCoerceUnsized;
  19 use rustc::ty::subst::{Kind, Subst, Substs};
  20 use rustc::ty::{self, Ty, TyCtxt};
  21
  22 use syntax::codemap::DUMMY_SP;
  23
  24 pub use rustc::ty::Instance;
  25
  26 fn fn_once_adapter_instance<'a, 'tcx>(
  27     tcx: TyCtxt<'a, 'tcx, 'tcx>,
  28     closure_did: DefId,
  29     substs: ty::ClosureSubsts<'tcx>,
  30     ) -> Instance<'tcx> {
  31     debug!("fn_once_adapter_shim({:?}, {:?})",
  32            closure_did,
  33            substs);
  34     let fn_once = tcx.lang_items().fn_once_trait().unwrap();
  35     let call_once = tcx.associated_items(fn_once)
  36         .find(|it| it.kind == ty::AssociatedKind::Method)
  37         .unwrap().def_id;
  38     let def = ty::InstanceDef::ClosureOnceShim { call_once };
  39
  40     let self_ty = tcx.mk_closure_from_closure_substs(
  41         closure_did, substs);
  42
  43     let sig = tcx.fn_sig(closure_did).subst(tcx, substs.substs);
  44     let sig = tcx.erase_late_bound_regions_and_normalize(&sig);
  45     assert_eq!(sig.inputs().len(), 1);
  46     let substs = tcx.mk_substs([
  47         Kind::from(self_ty),
  48         Kind::from(sig.inputs()[0]),
  49     ].iter().cloned());
  50
  51     debug!("fn_once_adapter_shim: self_ty={:?} sig={:?}", self_ty, sig);
  52     Instance { def, substs }
  53 }
  54
  55 fn needs_fn_once_adapter_shim(actual_closure_kind: ty::ClosureKind,
  56                               trait_closure_kind: ty::ClosureKind)
  57                               -> Result<bool, ()>
  58 {
  59     match (actual_closure_kind, trait_closure_kind) {
  60         (ty::ClosureKind::Fn, ty::ClosureKind::Fn) |
  61         (ty::ClosureKind::FnMut, ty::ClosureKind::FnMut) |
  62         (ty::ClosureKind::FnOnce, ty::ClosureKind::FnOnce) => {
  63             // No adapter needed.
  64            Ok(false)
  65         }
  66         (ty::ClosureKind::Fn, ty::ClosureKind::FnMut) => {
  67             // The closure fn `llfn` is a `fn(&self, ...)`.  We want a
  68             // `fn(&mut self, ...)`. In fact, at trans time, these are
  69             // basically the same thing, so we can just return llfn.
  70             Ok(false)
  71         }
  72         (ty::ClosureKind::Fn, ty::ClosureKind::FnOnce) |
  73         (ty::ClosureKind::FnMut, ty::ClosureKind::FnOnce) => {
  74             // The closure fn `llfn` is a `fn(&self, ...)` or `fn(&mut
  75             // self, ...)`.  We want a `fn(self, ...)`. We can produce
  76             // this by doing something like:
  77             //
  78             //     fn call_once(self, ...) { call_mut(&self, ...) }
  79             //     fn call_once(mut self, ...) { call_mut(&mut self, ...) }
  80             //
  81             // These are both the same at trans time.
  82             Ok(true)
  83         }
  84         _ => Err(()),
  85     }
  86 }
  87
  88 pub fn resolve_closure<'a, 'tcx> (
  89     scx: &SharedCrateContext<'a, 'tcx>,
  90     def_id: DefId,
  91     substs: ty::ClosureSubsts<'tcx>,
  92     requested_kind: ty::ClosureKind)
  93     -> Instance<'tcx>
  94 {
  95     let actual_kind = scx.tcx().closure_kind(def_id);
  96
  97     match needs_fn_once_adapter_shim(actual_kind, requested_kind) {
  98         Ok(true) => fn_once_adapter_instance(scx.tcx(), def_id, substs),
  99         _ => Instance::new(def_id, substs.substs)
 100     }
 101 }
 102
 103 fn resolve_associated_item<'a, 'tcx>(
 104     scx: &SharedCrateContext<'a, 'tcx>,
 105     trait_item: &ty::AssociatedItem,
 106     trait_id: DefId,
 107     rcvr_substs: &'tcx Substs<'tcx>
 108 ) -> Instance<'tcx> {
 109     let tcx = scx.tcx();
 110     let def_id = trait_item.def_id;
 111     debug!("resolve_associated_item(trait_item={:?}, \
 112                                     trait_id={:?}, \
 113                                     rcvr_substs={:?})",
 114            def_id, trait_id, rcvr_substs);
 115
 116     let trait_ref = ty::TraitRef::from_method(tcx, trait_id, rcvr_substs);
 117     let vtbl = tcx.trans_fulfill_obligation(DUMMY_SP, ty::Binder(trait_ref));
 118
 119     // Now that we know which impl is being used, we can dispatch to
 120     // the actual function:
 121     match vtbl {
 122         traits::VtableImpl(impl_data) => {
 123             let (def_id, substs) = traits::find_associated_item(
 124                 tcx, trait_item, rcvr_substs, &impl_data);
 125             let substs = tcx.erase_regions(&substs);
 126             ty::Instance::new(def_id, substs)
 127         }
 128         traits::VtableGenerator(closure_data) => {
 129             Instance {
 130                 def: ty::InstanceDef::Item(closure_data.closure_def_id),
 131                 substs: closure_data.substs.substs
 132             }
 133         }
 134         traits::VtableClosure(closure_data) => {
 135             let trait_closure_kind = tcx.lang_items().fn_trait_kind(trait_id).unwrap();
 136             resolve_closure(scx, closure_data.closure_def_id, closure_data.substs,
 137                             trait_closure_kind)
 138         }
 139         traits::VtableFnPointer(ref data) => {
 140             Instance {
 141                 def: ty::InstanceDef::FnPtrShim(trait_item.def_id, data.fn_ty),
 142                 substs: rcvr_substs
 143             }
 144         }
 145         traits::VtableObject(ref data) => {
 146             let index = tcx.get_vtable_index_of_object_method(data, def_id);
 147             Instance {
 148                 def: ty::InstanceDef::Virtual(def_id, index),
 149                 substs: rcvr_substs
 150             }
 151         }
 152         traits::VtableBuiltin(..) if Some(trait_id) == tcx.lang_items().clone_trait() => {
 153             Instance {
 154                 def: ty::InstanceDef::CloneShim(def_id, trait_ref.self_ty()),
 155                 substs: rcvr_substs
 156             }
 157         }
 158         _ => {
 159             bug!("static call to invalid vtable: {:?}", vtbl)
 160         }
 161     }
 162 }
 163
 164 /// The point where linking happens. Resolve a (def_id, substs)
 165 /// pair to an instance.
 166 pub fn resolve<'a, 'tcx>(
 167     scx: &SharedCrateContext<'a, 'tcx>,
 168     def_id: DefId,
 169     substs: &'tcx Substs<'tcx>
 170 ) -> Instance<'tcx> {
 171     debug!("resolve(def_id={:?}, substs={:?})",
 172            def_id, substs);
 173     let result = if let Some(trait_def_id) = scx.tcx().trait_of_item(def_id) {
 174         debug!(" => associated item, attempting to find impl");
 175         let item = scx.tcx().associated_item(def_id);
 176         resolve_associated_item(scx, &item, trait_def_id, substs)
 177     } else {
 178         let item_type = def_ty(scx, def_id, substs);
 179         let def = match item_type.sty {
 180             ty::TyFnDef(..) if {
 181                     let f = item_type.fn_sig(scx.tcx());
 182                     f.abi() == Abi::RustIntrinsic ||
 183                     f.abi() == Abi::PlatformIntrinsic
 184                 } =>
 185             {
 186                 debug!(" => intrinsic");
 187                 ty::InstanceDef::Intrinsic(def_id)
 188             }
 189             _ => {
 190                 if Some(def_id) == scx.tcx().lang_items().drop_in_place_fn() {
 191                     let ty = substs.type_at(0);
 192                     if glue::needs_drop_glue(scx, ty) {
 193                         debug!(" => nontrivial drop glue");
 194                         ty::InstanceDef::DropGlue(def_id, Some(ty))
 195                     } else {
 196                         debug!(" => trivial drop glue");
 197                         ty::InstanceDef::DropGlue(def_id, None)
 198                     }
 199                 } else {
 200                     debug!(" => free item");
 201                     ty::InstanceDef::Item(def_id)
 202                 }
 203             }
 204         };
 205         Instance { def, substs }
 206     };
 207     debug!("resolve(def_id={:?}, substs={:?}) = {}",
 208            def_id, substs, result);
 209     result
 210 }
 211
 212 pub fn resolve_drop_in_place<'a, 'tcx>(
 213     scx: &SharedCrateContext<'a, 'tcx>,
 214     ty: Ty<'tcx>)
 215     -> ty::Instance<'tcx>
 216 {
 217     let def_id = scx.tcx().require_lang_item(DropInPlaceFnLangItem);
 218     let substs = scx.tcx().intern_substs(&[Kind::from(ty)]);
 219     resolve(scx, def_id, substs)
 220 }
 221
 222 pub fn custom_coerce_unsize_info<'scx, 'tcx>(scx: &SharedCrateContext<'scx, 'tcx>,
 223                                              source_ty: Ty<'tcx>,
 224                                              target_ty: Ty<'tcx>)
 225                                              -> CustomCoerceUnsized {
 226     let trait_ref = ty::Binder(ty::TraitRef {
 227         def_id: scx.tcx().lang_items().coerce_unsized_trait().unwrap(),
 228         substs: scx.tcx().mk_substs_trait(source_ty, &[target_ty])
 229     });
 230
 231     match scx.tcx().trans_fulfill_obligation(DUMMY_SP, trait_ref) {
 232         traits::VtableImpl(traits::VtableImplData { impl_def_id, .. }) => {
 233             scx.tcx().coerce_unsized_info(impl_def_id).custom_kind.unwrap()
 234         }
 235         vtable => {
 236             bug!("invalid CoerceUnsized vtable: {:?}", vtable);
 237         }
 238     }
 239 }
 240
 241 /// Returns the normalized type of a struct field
 242 pub fn field_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 243                           param_substs: &Substs<'tcx>,
 244                           f: &'tcx ty::FieldDef)
 245                           -> Ty<'tcx>
 246 {
 247     tcx.normalize_associated_type(&f.ty(tcx, param_substs))
 248 }
 249