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