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