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::*;
  37 pub use rustc_mir::monomorphize::item::MonoItemExt as BaseMonoItemExt;
  38
  39 pub trait MonoItemExt<'a, 'tcx>: fmt::Debug + BaseMonoItemExt<'a, 'tcx> {
  40     fn define(&self, cx: &CodegenCx<'a, 'tcx>) {
  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                 let attrs = tcx.get_attrs(def_id);
  59
  60                 consts::codegen_static(&cx, def_id, is_mutable, &attrs);
  61             }
  62             MonoItem::GlobalAsm(node_id) => {
  63                 let item = cx.tcx.hir.expect_item(node_id);
  64                 if let hir::ItemGlobalAsm(ref ga) = item.node {
  65                     asm::codegen_global_asm(cx, ga);
  66                 } else {
  67                     span_bug!(item.span, "Mismatch between hir::Item type and MonoItem type")
  68                 }
  69             }
  70             MonoItem::Fn(instance) => {
  71                 base::codegen_instance(&cx, instance);
  72             }
  73         }
  74
  75         debug!("END IMPLEMENTING '{} ({})' in cgu {}",
  76                self.to_string(cx.tcx),
  77                self.to_raw_string(),
  78                cx.codegen_unit.name());
  79     }
  80
  81     fn predefine(&self,
  82                  cx: &CodegenCx<'a, 'tcx>,
  83                  linkage: Linkage,
  84                  visibility: Visibility) {
  85         debug!("BEGIN PREDEFINING '{} ({})' in cgu {}",
  86                self.to_string(cx.tcx),
  87                self.to_raw_string(),
  88                cx.codegen_unit.name());
  89
  90         let symbol_name = self.symbol_name(cx.tcx).as_str();
  91
  92         debug!("symbol {}", &symbol_name);
  93
  94         match *self.as_mono_item() {
  95             MonoItem::Static(def_id) => {
  96                 predefine_static(cx, def_id, linkage, visibility, &symbol_name);
  97             }
  98             MonoItem::Fn(instance) => {
  99                 predefine_fn(cx, instance, linkage, visibility, &symbol_name);
 100             }
 101             MonoItem::GlobalAsm(..) => {}
 102         }
 103
 104         debug!("END PREDEFINING '{} ({})' in cgu {}",
 105                self.to_string(cx.tcx),
 106                self.to_raw_string(),
 107                cx.codegen_unit.name());
 108     }
 109
 110     fn to_raw_string(&self) -> String {
 111         match *self.as_mono_item() {
 112             MonoItem::Fn(instance) => {
 113                 format!("Fn({:?}, {})",
 114                          instance.def,
 115                          instance.substs.as_ptr() as usize)
 116             }
 117             MonoItem::Static(id) => {
 118                 format!("Static({:?})", id)
 119             }
 120             MonoItem::GlobalAsm(id) => {
 121                 format!("GlobalAsm({:?})", id)
 122             }
 123         }
 124     }
 125 }
 126
 127 impl<'a, 'tcx> MonoItemExt<'a, 'tcx> for MonoItem<'tcx> {}
 128
 129 fn predefine_static<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 130                               def_id: DefId,
 131                               linkage: Linkage,
 132                               visibility: Visibility,
 133                               symbol_name: &str) {
 134     let instance = Instance::mono(cx.tcx, def_id);
 135     let ty = instance.ty(cx.tcx);
 136     let llty = cx.layout_of(ty).llvm_type(cx);
 137
 138     let g = declare::define_global(cx, symbol_name, llty).unwrap_or_else(|| {
 139         cx.sess().span_fatal(cx.tcx.def_span(def_id),
 140             &format!("symbol `{}` is already defined", symbol_name))
 141     });
 142
 143     unsafe {
 144         llvm::LLVMRustSetLinkage(g, base::linkage_to_llvm(linkage));
 145         llvm::LLVMRustSetVisibility(g, base::visibility_to_llvm(visibility));
 146     }
 147
 148     cx.instances.borrow_mut().insert(instance, g);
 149     cx.statics.borrow_mut().insert(g, def_id);
 150 }
 151
 152 fn predefine_fn<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 153                           instance: Instance<'tcx>,
 154                           linkage: Linkage,
 155                           visibility: Visibility,
 156                           symbol_name: &str) {
 157     assert!(!instance.substs.needs_infer() &&
 158             !instance.substs.has_param_types());
 159
 160     let mono_ty = instance.ty(cx.tcx);
 161     let attrs = instance.def.attrs(cx.tcx);
 162     let lldecl = declare::declare_fn(cx, symbol_name, mono_ty);
 163     unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
 164     base::set_link_section(cx, lldecl, &attrs);
 165     if linkage == Linkage::LinkOnceODR ||
 166         linkage == Linkage::WeakODR {
 167         llvm::SetUniqueComdat(cx.llmod, lldecl);
 168     }
 169
 170     // If we're compiling the compiler-builtins crate, e.g. the equivalent of
 171     // compiler-rt, then we want to implicitly compile everything with hidden
 172     // visibility as we're going to link this object all over the place but
 173     // don't want the symbols to get exported.
 174     if linkage != Linkage::Internal && linkage != Linkage::Private &&
 175        cx.tcx.is_compiler_builtins(LOCAL_CRATE) {
 176         unsafe {
 177             llvm::LLVMRustSetVisibility(lldecl, llvm::Visibility::Hidden);
 178         }
 179     } else {
 180         unsafe {
 181             llvm::LLVMRustSetVisibility(lldecl, base::visibility_to_llvm(visibility));
 182         }
 183     }
 184
 185     debug!("predefine_fn: mono_ty = {:?} instance = {:?}", mono_ty, instance);
 186     if instance.def.is_inline(cx.tcx) {
 187         attributes::inline(lldecl, attributes::InlineAttr::Hint);
 188     }
 189     attributes::from_fn_attrs(cx, lldecl, instance.def.def_id());
 190
 191     cx.instances.borrow_mut().insert(instance, lldecl);
 192 }