src/librustc/middle/trans/inline.rs

   1 // Copyright 2012 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::trans::base::{push_ctxt, trans_item, get_item_val, trans_fn};
  15 use middle::trans::common::*;
  16 use middle::ty;
  17
  18 use syntax::ast;
  19 use syntax::ast_util::{local_def, PostExpansionMethod};
  20 use syntax::ast_util;
  21
  22 pub fn maybe_instantiate_inline(ccx: &CrateContext, fn_id: ast::DefId)
  23     -> ast::DefId {
  24     let _icx = push_ctxt("maybe_instantiate_inline");
  25     match ccx.external().borrow().find(&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 local_def(node_id);
  31         }
  32         Some(&None) => {
  33             return fn_id; // 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             |a,b,c,d| astencode::decode_inlined_item(a, b, c, d));
  44     return match csearch_result {
  45         csearch::not_found => {
  46             ccx.external().borrow_mut().insert(fn_id, None);
  47             fn_id
  48         }
  49         csearch::found(ast::IIItem(item)) => {
  50             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
  51             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
  52
  53             ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
  54             trans_item(ccx, &*item);
  55
  56             let linkage = match item.node {
  57                 ast::ItemFn(_, _, _, ref generics, _) => {
  58                     if generics.is_type_parameterized() {
  59                         // Generics have no symbol, so they can't be given any
  60                         // linkage.
  61                         None
  62                     } else {
  63                         if ccx.sess().opts.cg.codegen_units == 1 {
  64                             // We could use AvailableExternallyLinkage here,
  65                             // but InternalLinkage allows LLVM to optimize more
  66                             // aggressively (at the cost of sometimes
  67                             // duplicating code).
  68                             Some(InternalLinkage)
  69                         } else {
  70                             // With multiple compilation units, duplicated code
  71                             // is more of a problem.  Also, `codegen_units > 1`
  72                             // means the user is okay with losing some
  73                             // performance.
  74                             Some(AvailableExternallyLinkage)
  75                         }
  76                     }
  77                 }
  78                 ast::ItemStatic(_, mutbl, _) => {
  79                     if !ast_util::static_has_significant_address(mutbl, item.attrs.as_slice()) {
  80                         // Inlined static items use internal linkage when
  81                         // possible, so that LLVM will coalesce globals with
  82                         // identical initializers.  (It only does this for
  83                         // globals with unnamed_addr and either internal or
  84                         // private linkage.)
  85                         Some(InternalLinkage)
  86                     } else {
  87                         // The address is significant, so we can't create an
  88                         // internal copy of the static.  (The copy would have a
  89                         // different address from the original.)
  90                         Some(AvailableExternallyLinkage)
  91                     }
  92                 }
  93                 _ => unreachable!(),
  94             };
  95
  96             match linkage {
  97                 Some(linkage) => {
  98                     let g = get_item_val(ccx, item.id);
  99                     SetLinkage(g, linkage);
 100                 }
 101                 None => {}
 102             }
 103
 104             local_def(item.id)
 105         }
 106         csearch::found(ast::IIForeign(item)) => {
 107             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
 108             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
 109             local_def(item.id)
 110         }
 111         csearch::found_parent(parent_id, ast::IIItem(item)) => {
 112             ccx.external().borrow_mut().insert(parent_id, Some(item.id));
 113             ccx.external_srcs().borrow_mut().insert(item.id, parent_id);
 114
 115           let mut my_id = 0;
 116           match item.node {
 117             ast::ItemEnum(_, _) => {
 118               let vs_here = ty::enum_variants(ccx.tcx(), local_def(item.id));
 119               let vs_there = ty::enum_variants(ccx.tcx(), parent_id);
 120               for (here, there) in vs_here.iter().zip(vs_there.iter()) {
 121                   if there.id == fn_id { my_id = here.id.node; }
 122                   ccx.external().borrow_mut().insert(there.id, Some(here.id.node));
 123               }
 124             }
 125             ast::ItemStruct(ref struct_def, _) => {
 126               match struct_def.ctor_id {
 127                 None => {}
 128                 Some(ctor_id) => {
 129                     ccx.external().borrow_mut().insert(fn_id, Some(ctor_id));
 130                     my_id = ctor_id;
 131                 }
 132               }
 133             }
 134             _ => ccx.sess().bug("maybe_instantiate_inline: item has a \
 135                                  non-enum, non-struct parent")
 136           }
 137           trans_item(ccx, &*item);
 138           local_def(my_id)
 139         }
 140         csearch::found_parent(_, _) => {
 141             ccx.sess().bug("maybe_get_item_ast returned a found_parent \
 142              with a non-item parent");
 143         }
 144         csearch::found(ast::IITraitItem(impl_did, impl_item)) => {
 145             match impl_item {
 146                 ast::ProvidedInlinedTraitItem(mth) |
 147                 ast::RequiredInlinedTraitItem(mth) => {
 148                     ccx.external().borrow_mut().insert(fn_id, Some(mth.id));
 149                     ccx.external_srcs().borrow_mut().insert(mth.id, fn_id);
 150
 151                     ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 152                 }
 153             }
 154
 155             match impl_item {
 156                 ast::ProvidedInlinedTraitItem(mth) => {
 157                     // If this is a default method, we can't look up the
 158                     // impl type. But we aren't going to translate anyways, so
 159                     // don't.
 160                     local_def(mth.id)
 161                 }
 162                 ast::RequiredInlinedTraitItem(mth) => {
 163                     let impl_tpt = ty::lookup_item_type(ccx.tcx(), impl_did);
 164                     let unparameterized = impl_tpt.generics.types.is_empty() &&
 165                             mth.pe_generics().ty_params.is_empty();
 166
 167                     if unparameterized {
 168                         let llfn = get_item_val(ccx, mth.id);
 169                         trans_fn(ccx,
 170                                  &*mth.pe_fn_decl(),
 171                                  &*mth.pe_body(),
 172                                  llfn,
 173                                  &param_substs::empty(),
 174                                  mth.id,
 175                                  []);
 176                         // Use InternalLinkage so LLVM can optimize more
 177                         // aggressively.
 178                         SetLinkage(llfn, InternalLinkage);
 179                     }
 180                     local_def(mth.id)
 181                 }
 182             }
 183         }
 184     };
 185 }