src/librustc/middle/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::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 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().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 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             |a,b,c,d| astencode::decode_inlined_item(a, b, c, d));
  44
  45     let inline_def = match csearch_result {
  46         csearch::not_found => {
  47             ccx.external().borrow_mut().insert(fn_id, None);
  48             return None;
  49         }
  50         csearch::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::ItemStatic(_, mutbl, _) => {
  80                     if !ast_util::static_has_significant_address(mutbl, item.attrs.as_slice()) {
  81                         // Inlined static items use internal linkage when
  82                         // possible, so that LLVM will coalesce globals with
  83                         // identical initializers.  (It only does this for
  84                         // globals with unnamed_addr and either internal or
  85                         // private linkage.)
  86                         Some(InternalLinkage)
  87                     } else {
  88                         // The address is significant, so we can't create an
  89                         // internal copy of the static.  (The copy would have a
  90                         // different address from the original.)
  91                         Some(AvailableExternallyLinkage)
  92                     }
  93                 }
  94                 _ => unreachable!(),
  95             };
  96
  97             match linkage {
  98                 Some(linkage) => {
  99                     let g = get_item_val(ccx, item.id);
 100                     SetLinkage(g, linkage);
 101                 }
 102                 None => {}
 103             }
 104
 105             local_def(item.id)
 106         }
 107         csearch::found(&ast::IIForeign(ref item)) => {
 108             ccx.external().borrow_mut().insert(fn_id, Some(item.id));
 109             ccx.external_srcs().borrow_mut().insert(item.id, fn_id);
 110             local_def(item.id)
 111         }
 112         csearch::found_parent(parent_id, &ast::IIItem(ref item)) => {
 113             ccx.external().borrow_mut().insert(parent_id, Some(item.id));
 114             ccx.external_srcs().borrow_mut().insert(item.id, parent_id);
 115
 116           let mut my_id = 0;
 117           match item.node {
 118             ast::ItemEnum(_, _) => {
 119               let vs_here = ty::enum_variants(ccx.tcx(), local_def(item.id));
 120               let vs_there = ty::enum_variants(ccx.tcx(), parent_id);
 121               for (here, there) in vs_here.iter().zip(vs_there.iter()) {
 122                   if there.id == fn_id { my_id = here.id.node; }
 123                   ccx.external().borrow_mut().insert(there.id, Some(here.id.node));
 124               }
 125             }
 126             ast::ItemStruct(ref struct_def, _) => {
 127               match struct_def.ctor_id {
 128                 None => {}
 129                 Some(ctor_id) => {
 130                     ccx.external().borrow_mut().insert(fn_id, Some(ctor_id));
 131                     my_id = ctor_id;
 132                 }
 133               }
 134             }
 135             _ => ccx.sess().bug("maybe_instantiate_inline: item has a \
 136                                  non-enum, non-struct parent")
 137           }
 138           trans_item(ccx, &**item);
 139           local_def(my_id)
 140         }
 141         csearch::found_parent(_, _) => {
 142             ccx.sess().bug("maybe_get_item_ast returned a found_parent \
 143              with a non-item parent");
 144         }
 145         csearch::found(&ast::IITraitItem(_, ref trait_item)) => {
 146             match *trait_item {
 147                 ast::RequiredMethod(_) => ccx.sess().bug("found RequiredMethod IITraitItem"),
 148                 ast::ProvidedMethod(ref mth) => {
 149                     ccx.external().borrow_mut().insert(fn_id, Some(mth.id));
 150                     ccx.external_srcs().borrow_mut().insert(mth.id, fn_id);
 151
 152                     ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 153
 154                     // If this is a default method, we can't look up the
 155                     // impl type. But we aren't going to translate anyways, so
 156                     // don't.
 157                     local_def(mth.id)
 158                 }
 159             }
 160         }
 161         csearch::found(&ast::IIImplItem(impl_did, ref impl_item)) => {
 162             match *impl_item {
 163                 ast::MethodImplItem(ref mth) => {
 164                     ccx.external().borrow_mut().insert(fn_id, Some(mth.id));
 165                     ccx.external_srcs().borrow_mut().insert(mth.id, fn_id);
 166
 167                     ccx.stats().n_inlines.set(ccx.stats().n_inlines.get() + 1);
 168
 169                     let impl_tpt = ty::lookup_item_type(ccx.tcx(), impl_did);
 170                     let unparameterized = impl_tpt.generics.types.is_empty() &&
 171                             mth.pe_generics().ty_params.is_empty();
 172
 173                     if unparameterized {
 174                         let llfn = get_item_val(ccx, mth.id);
 175                         trans_fn(ccx,
 176                                  &*mth.pe_fn_decl(),
 177                                  &*mth.pe_body(),
 178                                  llfn,
 179                                  &param_substs::empty(),
 180                                  mth.id,
 181                                  []);
 182                         // Use InternalLinkage so LLVM can optimize more
 183                         // aggressively.
 184                         SetLinkage(llfn, InternalLinkage);
 185                     }
 186                     local_def(mth.id)
 187                 }
 188             }
 189         }
 190     };
 191
 192     return Some(inline_def);
 193 }
 194
 195 pub fn get_local_instance(ccx: &CrateContext, fn_id: ast::DefId)
 196     -> Option<ast::DefId> {
 197     if fn_id.krate == ast::LOCAL_CRATE {
 198         Some(fn_id)
 199     } else {
 200         instantiate_inline(ccx, fn_id)
 201     }
 202 }
 203
 204 pub fn maybe_instantiate_inline(ccx: &CrateContext, fn_id: ast::DefId) -> ast::DefId {
 205     get_local_instance(ccx, fn_id).unwrap_or(fn_id)
 206 }