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