src/librustc_trans/trans/inline.rs

   1 // Copyright 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 llvm::{AvailableExternallyLinkage, InternalLinkage, SetLinkage};
  12 use metadata::csearch;
  13 use metadata::inline::InlinedItem;
  14 use middle::astencode;
  15 use middle::def_id::DefId;
  16 use middle::subst::Substs;
  17 use trans::base::{push_ctxt, trans_item, get_item_val, trans_fn};
  18 use trans::common::*;
  19
  20 use rustc_front::hir;
  21
  22
  23 fn instantiate_inline(ccx: &CrateContext, fn_id: DefId)
  24     -> Option<DefId> {
  25     debug!("instantiate_inline({:?})", fn_id);
  26     let _icx = push_ctxt("instantiate_inline");
  27
  28     match ccx.external().borrow().get(&fn_id) {
  29         Some(&Some(node_id)) => {
  30             // Already inline
  31             debug!("instantiate_inline({}): already inline as node id {}",
  32                    ccx.tcx().item_path_str(fn_id), node_id);
  33             return Some(DefId::local(node_id));
  34         }
  35         Some(&None) => {
  36             return None; // Not inlinable
  37         }
  38         None => {
  39             // Not seen yet
  40         }
  41     }
  42
  43     let csearch_result =
  44         csearch::maybe_get_item_ast(
  45             ccx.tcx(), fn_id,
  46             Box::new(|a,b,c,d| astencode::decode_inlined_item(a, b, c, d)));
  47
  48     let inline_id = match csearch_result {
  49         csearch::FoundAst::NotFound => {
  50             ccx.external().borrow_mut().insert(fn_id, None);
  51             return None;
  52         }
  53         csearch::FoundAst::Found(&InlinedItem::Item(ref item)) => {
  54             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
  55             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
  56
  57             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
  58             trans_item(ccx, item);
  59
  60             let linkage = match item.node {
  61                 hir::ItemFn(_, _, _, _, ref generics, _) => {
  62                     if generics.is_type_parameterized() {
  63                         // Generics have no symbol, so they can't be given any
  64                         // linkage.
  65                         None
  66                     } else {
  67                         if ccx.sess().opts.cg.codegen_units == 1 {
  68                             // We could use AvailableExternallyLinkage here,
  69                             // but InternalLinkage allows LLVM to optimize more
  70                             // aggressively (at the cost of sometimes
  71                             // duplicating code).
  72                             Some(InternalLinkage)
  73                         } else {
  74                             // With multiple compilation units, duplicated code
  75                             // is more of a problem.  Also, `codegen_units > 1`
  76                             // means the user is okay with losing some
  77                             // performance.
  78                             Some(AvailableExternallyLinkage)
  79                         }
  80                     }
  81                 }
  82                 hir::ItemConst(..) => None,
  83                 _ => unreachable!(),
  84             };
  85
  86             match linkage {
  87                 Some(linkage) => {
  88                     let g = get_item_val(ccx, item.id);
  89                     SetLinkage(g, linkage);
  90                 }
  91                 None => {}
  92             }
  93
  94             item.id
  95         }
  96         csearch::FoundAst::Found(&InlinedItem::Foreign(ref item)) => {
  97             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
  98             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
  99             item.id
 100         }
 101         csearch::FoundAst::FoundParent(parent_id, &InlinedItem::Item(ref item)) => {
 102             ccx.external().borrow_mut().insert(parent_id, Some(item.id));
 103             ccx.external_srcs().borrow_mut().insert(item.id, parent_id);
 104
 105             let mut my_id = 0;
 106             match item.node {
 107                 hir::ItemEnum(ref ast_def, _) => {
 108                     let ast_vs = &ast_def.variants;
 109                     let ty_vs = &ccx.tcx().lookup_adt_def(parent_id).variants;
 110                     assert_eq!(ast_vs.len(), ty_vs.len());
 111                     for (ast_v, ty_v) in ast_vs.iter().zip(ty_vs.iter()) {
 112                         if ty_v.did == fn_id { my_id = ast_v.node.id; }
 113                         ccx.external().borrow_mut().insert(ty_v.did, Some(ast_v.node.id));
 114                     }
 115                 }
 116                 hir::ItemStruct(ref struct_def, _) => {
 117                     match struct_def.ctor_id {
 118                         None => ccx.sess().bug("instantiate_inline: called on a \
 119                                                 non-tuple struct"),
 120                         Some(ctor_id) => {
 121                             ccx.external().borrow_mut().insert(fn_id, Some(ctor_id));
 122                             my_id = ctor_id;
 123                         }
 124                     }
 125                 }
 126                 _ => ccx.sess().bug("instantiate_inline: item has a \
 127                                  non-enum, non-struct parent")
 128             }
 129             trans_item(ccx, &**item);
 130             my_id
 131         }
 132         csearch::FoundAst::FoundParent(_, _) => {
 133             ccx.sess().bug("maybe_get_item_ast returned a FoundParent \
 134                             with a non-item parent");
 135         }
 136         csearch::FoundAst::Found(&InlinedItem::TraitItem(_, ref trait_item)) => {
 137             ccx.external().borrow_mut().insert(fn_id, Some(trait_item.id));
 138             ccx.external_srcs().borrow_mut().insert(trait_item.id, fn_id);
 139
 140             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 141
 142             // Associated consts already have to be evaluated in `typeck`, so
 143             // the logic to do that already exists in `middle`. In order to
 144             // reuse that code, it needs to be able to look up the traits for
 145             // inlined items.
 146             let ty_trait_item = ccx.tcx().impl_or_trait_item(fn_id).clone();
 147             ccx.tcx().impl_or_trait_items.borrow_mut()
 148                      .insert(DefId::local(trait_item.id), ty_trait_item);
 149
 150             // If this is a default method, we can't look up the
 151             // impl type. But we aren't going to translate anyways, so
 152             // don't.
 153             trait_item.id
 154         }
 155         csearch::FoundAst::Found(&InlinedItem::ImplItem(impl_did, ref impl_item)) => {
 156             ccx.external().borrow_mut().insert(fn_id, Some(impl_item.id));
 157             ccx.external_srcs().borrow_mut().insert(impl_item.id, fn_id);
 158
 159             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 160
 161             // Translate monomorphic impl methods immediately.
 162             if let hir::MethodImplItem(ref sig, ref body) = impl_item.node {
 163                 let impl_tpt = ccx.tcx().lookup_item_type(impl_did);
 164                 if impl_tpt.generics.types.is_empty() &&
 165                         sig.generics.ty_params.is_empty() {
 166                     let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
 167                     let llfn = get_item_val(ccx, impl_item.id);
 168                     trans_fn(ccx,
 169                              &sig.decl,
 170                              body,
 171                              llfn,
 172                              empty_substs,
 173                              impl_item.id,
 174                              &[]);
 175                     // See linkage comments on items.
 176                     if ccx.sess().opts.cg.codegen_units == 1 {
 177                         SetLinkage(llfn, InternalLinkage);
 178                     } else {
 179                         SetLinkage(llfn, AvailableExternallyLinkage);
 180                     }
 181                 }
 182             }
 183
 184             impl_item.id
 185         }
 186     };
 187
 188     Some(DefId::local(inline_id))
 189 }
 190
 191 pub fn get_local_instance(ccx: &CrateContext, fn_id: DefId)
 192     -> Option<DefId> {
 193     if fn_id.is_local() {
 194         Some(fn_id)
 195     } else {
 196         instantiate_inline(ccx, fn_id)
 197     }
 198 }
 199
 200 pub fn maybe_instantiate_inline(ccx: &CrateContext, fn_id: DefId) -> DefId {
 201     get_local_instance(ccx, fn_id).unwrap_or(fn_id)
 202 }