compiler/rustc_codegen_llvm/src/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_codegen_ssa::traits::*;
   8 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
   9 pub use rustc_middle::mir::mono::MonoItem;
  10 use rustc_middle::mir::mono::{Linkage, Visibility};
  11 use rustc_middle::ty::layout::FnAbiExt;
  12 use rustc_middle::ty::{self, Instance, TypeFoldable};
  13 use rustc_target::abi::LayoutOf;
  14 use tracing::debug;
  15
  16 impl PreDefineMethods<'tcx> for CodegenCx<'ll, 'tcx> {
  17     fn predefine_static(
  18         &self,
  19         def_id: DefId,
  20         linkage: Linkage,
  21         visibility: Visibility,
  22         symbol_name: &str,
  23     ) {
  24         let instance = Instance::mono(self.tcx, def_id);
  25         let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
  26         let llty = self.layout_of(ty).llvm_type(self);
  27
  28         let g = self.define_global(symbol_name, llty).unwrap_or_else(|| {
  29             self.sess().span_fatal(
  30                 self.tcx.def_span(def_id),
  31                 &format!("symbol `{}` is already defined", symbol_name),
  32             )
  33         });
  34
  35         unsafe {
  36             llvm::LLVMRustSetLinkage(g, base::linkage_to_llvm(linkage));
  37             llvm::LLVMRustSetVisibility(g, base::visibility_to_llvm(visibility));
  38         }
  39
  40         self.instances.borrow_mut().insert(instance, g);
  41     }
  42
  43     fn predefine_fn(
  44         &self,
  45         instance: Instance<'tcx>,
  46         linkage: Linkage,
  47         visibility: Visibility,
  48         symbol_name: &str,
  49     ) {
  50         assert!(!instance.substs.needs_infer());
  51
  52         let fn_abi = FnAbi::of_instance(self, instance, &[]);
  53         let lldecl = self.declare_fn(symbol_name, &fn_abi);
  54         unsafe { llvm::LLVMRustSetLinkage(lldecl, base::linkage_to_llvm(linkage)) };
  55         let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
  56         base::set_link_section(lldecl, &attrs);
  57         if linkage == Linkage::LinkOnceODR || linkage == Linkage::WeakODR {
  58             llvm::SetUniqueComdat(self.llmod, lldecl);
  59         }
  60
  61         // If we're compiling the compiler-builtins crate, e.g., the equivalent of
  62         // compiler-rt, then we want to implicitly compile everything with hidden
  63         // visibility as we're going to link this object all over the place but
  64         // don't want the symbols to get exported.
  65         if linkage != Linkage::Internal
  66             && linkage != Linkage::Private
  67             && self.tcx.is_compiler_builtins(LOCAL_CRATE)
  68         {
  69             unsafe {
  70                 llvm::LLVMRustSetVisibility(lldecl, llvm::Visibility::Hidden);
  71             }
  72         } else {
  73             unsafe {
  74                 llvm::LLVMRustSetVisibility(lldecl, base::visibility_to_llvm(visibility));
  75             }
  76         }
  77
  78         debug!("predefine_fn: instance = {:?}", instance);
  79
  80         attributes::from_fn_attrs(self, lldecl, instance);
  81
  82         self.instances.borrow_mut().insert(instance, lldecl);
  83     }
  84 }