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             let node_def_id = ccx.tcx().map.local_def_id(node_id);
  34             return Some(node_def_id);
  35         }
  36         Some(&None) => {
  37             return None; // Not inlinable
  38         }
  39         None => {
  40             // Not seen yet
  41         }
  42     }
  43
  44     let csearch_result =
  45         csearch::maybe_get_item_ast(
  46             ccx.tcx(), fn_id,
  47             Box::new(astencode::decode_inlined_item));
  48
  49     let inline_id = match csearch_result {
  50         csearch::FoundAst::NotFound => {
  51             ccx.external().borrow_mut().insert(fn_id, None);
  52             return None;
  53         }
  54         csearch::FoundAst::Found(&InlinedItem::Item(ref item)) => {
  55             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
  56             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
  57
  58             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
  59             trans_item(ccx, item);
  60
  61             let linkage = match item.node {
  62                 hir::ItemFn(_, _, _, _, ref generics, _) => {
  63                     if generics.is_type_parameterized() {
  64                         // Generics have no symbol, so they can't be given any
  65                         // linkage.
  66                         None
  67                     } else {
  68                         if ccx.sess().opts.cg.codegen_units == 1 {
  69                             // We could use AvailableExternallyLinkage here,
  70                             // but InternalLinkage allows LLVM to optimize more
  71                             // aggressively (at the cost of sometimes
  72                             // duplicating code).
  73                             Some(InternalLinkage)
  74                         } else {
  75                             // With multiple compilation units, duplicated code
  76                             // is more of a problem.  Also, `codegen_units > 1`
  77                             // means the user is okay with losing some
  78                             // performance.
  79                             Some(AvailableExternallyLinkage)
  80                         }
  81                     }
  82                 }
  83                 hir::ItemConst(..) => None,
  84                 _ => unreachable!(),
  85             };
  86
  87             match linkage {
  88                 Some(linkage) => {
  89                     let g = get_item_val(ccx, item.id);
  90                     SetLinkage(g, linkage);
  91                 }
  92                 None => {}
  93             }
  94
  95             item.id
  96         }
  97         csearch::FoundAst::Found(&InlinedItem::Foreign(ref item)) => {
  98             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
  99             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
 100             item.id
 101         }
 102         csearch::FoundAst::FoundParent(parent_id, &InlinedItem::Item(ref item)) => {
 103             ccx.external().borrow_mut().insert(parent_id, Some(item.id));
 104             ccx.external_srcs().borrow_mut().insert(item.id, parent_id);
 105
 106             let mut my_id = 0;
 107             match item.node {
 108                 hir::ItemEnum(ref ast_def, _) => {
 109                     let ast_vs = &ast_def.variants;
 110                     let ty_vs = &ccx.tcx().lookup_adt_def(parent_id).variants;
 111                     assert_eq!(ast_vs.len(), ty_vs.len());
 112                     for (ast_v, ty_v) in ast_vs.iter().zip(ty_vs.iter()) {
 113                         if ty_v.did == fn_id { my_id = ast_v.node.data.id; }
 114                         ccx.external().borrow_mut().insert(ty_v.did, Some(ast_v.node.data.id));
 115                     }
 116                 }
 117                 hir::ItemStruct(ref struct_def, _) => {
 118                     if struct_def.is_struct() {
 119                         ccx.sess().bug("instantiate_inline: called on a \
 120                                                                  non-tuple struct")
 121                     } else {
 122                         ccx.external().borrow_mut().insert(fn_id, Some(struct_def.id));
 123                         my_id = struct_def.id;
 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             let trait_item_def_id = ccx.tcx().map.local_def_id(trait_item.id);
 148             ccx.tcx().impl_or_trait_items.borrow_mut()
 149                      .insert(trait_item_def_id, ty_trait_item);
 150
 151             // If this is a default method, we can't look up the
 152             // impl type. But we aren't going to translate anyways, so
 153             // don't.
 154             trait_item.id
 155         }
 156         csearch::FoundAst::Found(&InlinedItem::ImplItem(impl_did, ref impl_item)) => {
 157             ccx.external().borrow_mut().insert(fn_id, Some(impl_item.id));
 158             ccx.external_srcs().borrow_mut().insert(impl_item.id, fn_id);
 159
 160             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 161
 162             // Translate monomorphic impl methods immediately.
 163             if let hir::MethodImplItem(ref sig, ref body) = impl_item.node {
 164                 let impl_tpt = ccx.tcx().lookup_item_type(impl_did);
 165                 if impl_tpt.generics.types.is_empty() &&
 166                         sig.generics.ty_params.is_empty() {
 167                     let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
 168                     let llfn = get_item_val(ccx, impl_item.id);
 169                     trans_fn(ccx,
 170                              &sig.decl,
 171                              body,
 172                              llfn,
 173                              empty_substs,
 174                              impl_item.id,
 175                              &[]);
 176                     // See linkage comments on items.
 177                     if ccx.sess().opts.cg.codegen_units == 1 {
 178                         SetLinkage(llfn, InternalLinkage);
 179                     } else {
 180                         SetLinkage(llfn, AvailableExternallyLinkage);
 181                     }
 182                 }
 183             }
 184
 185             impl_item.id
 186         }
 187     };
 188
 189     let inline_def_id = ccx.tcx().map.local_def_id(inline_id);
 190     Some(inline_def_id)
 191 }
 192
 193 pub fn get_local_instance(ccx: &CrateContext, fn_id: DefId)
 194     -> Option<DefId> {
 195     if let Some(_) = ccx.tcx().map.as_local_node_id(fn_id) {
 196         Some(fn_id)
 197     } else {
 198         instantiate_inline(ccx, fn_id)
 199     }
 200 }
 201
 202 pub fn maybe_instantiate_inline(ccx: &CrateContext, fn_id: DefId) -> DefId {
 203     get_local_instance(ccx, fn_id).unwrap_or(fn_id)
 204 }