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