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