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