src/librustc_codegen_llvm/mono_item.rs

   1 // Copyright 2016 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 //! Walks the crate looking for items/impl-items/trait-items that have
  12 //! either a `rustc_symbol_name` or `rustc_item_path` attribute and
  13 //! generates an error giving, respectively, the symbol name or
  14 //! item-path. This is used for unit testing the code that generates
  15 //! paths etc in all kinds of annoying scenarios.
  16
  17 use asm;
  18 use attributes;
  19 use base;
  20 use consts;
  21 use context::CodegenCx;
  22 use declare;
  23 use llvm;
  24 use monomorphize::Instance;
  25 use type_of::LayoutLlvmExt;
  26 use rustc::hir;
  27 use rustc::hir::def::Def;
  28 use rustc::hir::def_id::DefId;
  29 use rustc::mir::mono::{Linkage, Visibility};
  30 use rustc::ty::TypeFoldable;
  31 use rustc::ty::layout::LayoutOf;
  32 use syntax::attr;
  33 use std::fmt;
  34
  35 pub use rustc::mir::mono::MonoItem;
  36
  37 pub use rustc_mir::monomorphize::item::*;
  38 pub use rustc_mir::monomorphize::item::MonoItemExt as BaseMonoItemExt;
  39
  40 pub trait MonoItemExt<'a, 'tcx>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> {
  41     fn define(&self, cx: &CodegenCx<'a, 'tcx>) {
  42         debug!("BEGIN IMPLEMENTING '{} ({})' in cgu {}",
  43                self.to_string(cx.tcx),
  44                self.to_raw_string(),
  45                cx.codegen_unit.name());
  46
  47         match *self.as_mono_item() {
  48             MonoItem::Static(def_id) => {
  49                 let tcx = cx.tcx;
  50                 let is_mutable = match tcx.describe_def(def_id) {
  51                     Some(Def::Static(_, is_mutable)) => is_mutable,
  52                     Some(other) => {
  53                         bug!("Expected Def::Static, found {:?}", other)
  54                     }
  55                     None => {
  56                         bug!("Expected Def::Static for {:?}, found nothing", def_id)
  57                     }
  58                 };
  59                 let attrs = tcx.get_attrs(def_id);
  60
  61                 consts::codegen_static(&cx, def_id, is_mutable, &attrs);
  62             }
  63             MonoItem::GlobalAsm(node_id) => {
  64                 let item = cx.tcx.hir.expect_item(node_id);
  65                 if let hir::ItemGlobalAsm(ref ga) = item.node {
  66                     asm::codegen_global_asm(cx, ga);
  67                 } else {
  68                     span_bug!(item.span, "Mismatch between hir::Item type and MonoItem type")
  69                 }
  70             }
  71             MonoItem::Fn(instance) => {
  72                 base::codegen_instance(&cx, instance);
  73             }
  74         }
  75
  76         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
  77                self.to_string(cx.tcx),
  78                self.to_raw_string(),
  79                cx.codegen_unit.name());
  80     }
  81
  82     fn predefine(&self,
  83                  cx: &CodegenCx<'a, 'tcx>,
  84                  linkage: Linkage,
  85                  visibility: Visibility) {
  86         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
  87                self.to_string(cx.tcx),
  88                self.to_raw_string(),
  89                cx.codegen_unit.name());
  90
  91         let symbol_name = self.symbol_name(cx.tcx).as_str();
  92
  93         debug!("symbol {}", &symbol_name);
  94
  95         match *self.as_mono_item() {
  96             MonoItem::Static(def_id) => {
  97                 predefine_static(cx, def_id, linkage, visibility, &symbol_name);
  98             }
  99             MonoItem::Fn(instance) => {
 100                 predefine_fn(cx, instance, linkage, visibility, &symbol_name);
 101             }
 102             MonoItem::GlobalAsm(..) => {}
 103         }
 104
 105         debug!("END PREDEFINING '{} ({})' in cgu {}",
 106                self.to_string(cx.tcx),
 107                self.to_raw_string(),
 108                cx.codegen_unit.name());
 109     }
 110
 111     fn to_raw_string(&self) -> String {
 112         match *self.as_mono_item() {
 113             MonoItem::Fn(instance) => {
 114                 format!("Fn({:?}, {})",
 115                          instance.def,
 116                          instance.substs.as_ptr() as usize)
 117             }
 118             MonoItem::Static(id) => {
 119                 format!("Static({:?})", id)
 120             }
 121             MonoItem::GlobalAsm(id) => {
 122                 format!("GlobalAsm({:?})", id)
 123             }
 124         }
 125     }
 126 }
 127
 128 impl<'a, 'tcx> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {}
 129
 130 fn predefine_static<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 131                               def_id: DefId,
 132                               linkage: Linkage,
 133                               visibility: Visibility,
 134                               symbol_name: &str) {
 135     let instance = Instance::mono(cx.tcx, def_id);
 136     let ty = instance.ty(cx.tcx);
 137     let llty = cx.layout_of(ty).llvm_type(cx);
 138
 139     let g = declare::define_global(cx, symbol_name, llty).unwrap_or_else(|| {
 140         cx.sess().span_fatal(cx.tcx.def_span(def_id),
 141             &format!("symbol `{}` is already defined", symbol_name))
 142     });
 143
 144     unsafe {
 145         llvm::LLVMRustSetLinkage(g, base::linkage_to_llvm(linkage));
 146         llvm::LLVMRustSetVisibility(g, base::visibility_to_llvm(visibility));
 147     }
 148
 149     cx.instances.borrow_mut().insert(instance, g);
 150     cx.statics.borrow_mut().insert(g, def_id);
 151 }
 152
 153 fn predefine_fn<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 154                           instance: Instance<'tcx>,
 155                           linkage: Linkage,
 156                           visibility: Visibility,
 157                           symbol_name: &str) {
 158     assert!(!instance.substs.needs_infer() &&
 159             !instance.substs.has_param_types());
 160
 161     let mono_ty = instance.ty(cx.tcx);
 162     let attrs = instance.def.attrs(cx.tcx);
 163     let lldecl = declare::declare_fn(cx, symbol_name, mono_ty);
 164     unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
 165     base::set_link_section(cx, lldecl, &attrs);
 166     if linkage == Linkage::LinkOnceODR ||
 167         linkage == Linkage::WeakODR {
 168         llvm::SetUniqueComdat(cx.llmod, lldecl);
 169     }
 170
 171     // If we're compiling the compiler-builtins crate, e.g. the equivalent of
 172     // compiler-rt, then we want to implicitly compile everything with hidden
 173     // visibility as we're going to link this object all over the place but
 174     // don't want the symbols to get exported.
 175     if linkage != Linkage::Internal && linkage != Linkage::Private &&
 176        attr::contains_name(cx.tcx.hir.krate_attrs(), "compiler_builtins") {
 177         unsafe {
 178             llvm::LLVMRustSetVisibility(lldecl, llvm::Visibility::Hidden);
 179         }
 180     } else {
 181         unsafe {
 182             llvm::LLVMRustSetVisibility(lldecl, base::visibility_to_llvm(visibility));
 183         }
 184     }
 185
 186     debug!("predefine_fn: mono_ty = {:?} instance = {:?}", mono_ty, instance);
 187     if instance.def.is_inline(cx.tcx) {
 188         attributes::inline(lldecl, attributes::InlineAttr::Hint);
 189     }
 190     attributes::from_fn_attrs(cx, lldecl, instance.def.def_id());
 191
 192     cx.instances.borrow_mut().insert(instance, lldecl);
 193 }