src/librustc_codegen_llvm/mono_item.rs

   1 use crate::abi::FnAbi;
   2 use crate::attributes;
   3 use crate::base;
   4 use crate::context::CodegenCx;
   5 use crate::llvm;
   6 use crate::type_of::LayoutLlvmExt;
   7 use rustc::hir::def_id::{DefId, LOCAL_CRATE};
   8 use rustc::mir::mono::{Linkage, Visibility};
   9 use rustc::ty::{TypeFoldable, Instance};
  10 use rustc::ty::layout::{FnAbiExt, LayoutOf};
  11 use rustc_codegen_ssa::traits::*;
  12 use log::debug;
  13
  14 pub use rustc::mir::mono::MonoItem;
  15
  16 impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
  17     fn predefine_static(&self,
  18                                   def_id: DefId,
  19                                   linkage: Linkage,
  20                                   visibility: Visibility,
  21                                   symbol_name: &str) {
  22         let instance = Instance::mono(self.tcx, def_id);
  23         let ty = instance.ty(self.tcx);
  24         let llty = self.layout_of(ty).llvm_type(self);
  25
  26         let g = self.define_global(symbol_name, llty).unwrap_or_else(|| {
  27             self.sess().span_fatal(self.tcx.def_span(def_id),
  28                 &format!("symbol `{}` is already defined", symbol_name))
  29         });
  30
  31         unsafe {
  32             llvm::LLVMRustSetLinkage(g, base::linkage_to_llvm(linkage));
  33             llvm::LLVMRustSetVisibility(g, base::visibility_to_llvm(visibility));
  34         }
  35
  36         self.instances.borrow_mut().insert(instance, g);
  37     }
  38
  39     fn predefine_fn(&self,
  40                     instance: Instance<'tcx>,
  41                     linkage: Linkage,
  42                     visibility: Visibility,
  43                     symbol_name: &str) {
  44         assert!(!instance.substs.needs_infer() &&
  45                 !instance.substs.has_param_types());
  46
  47         let fn_abi = FnAbi::of_instance(self, instance, &[]);
  48         let lldecl = self.declare_fn(symbol_name, &fn_abi);
  49         unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
  50         let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
  51         base::set_link_section(lldecl, &attrs);
  52         if linkage == Linkage::LinkOnceODR ||
  53             linkage == Linkage::WeakODR {
  54             llvm::SetUniqueComdat(self.llmod, lldecl);
  55         }
  56
  57         // If we're compiling the compiler-builtins crate, e.g., the equivalent of
  58         // compiler-rt, then we want to implicitly compile everything with hidden
  59         // visibility as we're going to link this object all over the place but
  60         // don't want the symbols to get exported.
  61         if linkage != Linkage::Internal && linkage != Linkage::Private &&
  62            self.tcx.is_compiler_builtins(LOCAL_CRATE) {
  63             unsafe {
  64                 llvm::LLVMRustSetVisibility(lldecl, llvm::Visibility::Hidden);
  65             }
  66         } else {
  67             unsafe {
  68                 llvm::LLVMRustSetVisibility(lldecl, base::visibility_to_llvm(visibility));
  69             }
  70         }
  71
  72         debug!("predefine_fn: instance = {:?}", instance);
  73
  74         attributes::from_fn_attrs(self, lldecl, instance, &fn_abi);
  75
  76         self.instances.borrow_mut().insert(instance, lldecl);
  77     }
  78 }