// Copyright 2012 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use llvm; use llvm::{SetUnnamedAddr}; use llvm::{ValueRef, True}; use rustc::hir::def_id::DefId; use rustc::hir::map as hir_map; use debuginfo; use base; use monomorphize::MonoItem; use common::{CodegenCx, val_ty}; use declare; use monomorphize::Instance; use type_::Type; use type_of::LayoutLlvmExt; use rustc::ty; use rustc::ty::layout::{Align, LayoutOf}; use rustc::hir; use std::ffi::{CStr, CString}; use syntax::ast; use syntax::attr; pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef { unsafe { llvm::LLVMConstPointerCast(val, ty.to_ref()) } } pub fn bitcast(val: ValueRef, ty: Type) -> ValueRef { unsafe { llvm::LLVMConstBitCast(val, ty.to_ref()) } } fn set_global_alignment(cx: &CodegenCx, gv: ValueRef, mut align: Align) { // The target may require greater alignment for globals than the type does. // Note: GCC and Clang also allow `__attribute__((aligned))` on variables, // which can force it to be smaller. Rust doesn't support this yet. if let Some(min) = cx.sess().target.target.options.min_global_align { match ty::layout::Align::from_bits(min, min) { Ok(min) => align = align.max(min), Err(err) => { cx.sess().err(&format!("invalid minimum global alignment: {}", err)); } } } unsafe { llvm::LLVMSetAlignment(gv, align.abi() as u32); } } pub fn addr_of_mut(cx: &CodegenCx, cv: ValueRef, align: Align, kind: &str) -> ValueRef { unsafe { let name = cx.generate_local_symbol_name(kind); let gv = declare::define_global(cx, &name[..], val_ty(cv)).unwrap_or_else(||{ bug!("symbol `{}` is already defined", name); }); llvm::LLVMSetInitializer(gv, cv); set_global_alignment(cx, gv, align); llvm::LLVMRustSetLinkage(gv, llvm::Linkage::PrivateLinkage); SetUnnamedAddr(gv, true); gv } } pub fn addr_of(cx: &CodegenCx, cv: ValueRef, align: Align, kind: &str) -> ValueRef { if let Some(&gv) = cx.const_globals.borrow().get(&cv) { unsafe { // Upgrade the alignment in cases where the same constant is used with different // alignment requirements let llalign = align.abi() as u32; if llalign > llvm::LLVMGetAlignment(gv) { llvm::LLVMSetAlignment(gv, llalign); } } return gv; } let gv = addr_of_mut(cx, cv, align, kind); unsafe { llvm::LLVMSetGlobalConstant(gv, True); } cx.const_globals.borrow_mut().insert(cv, gv); gv } pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef { let instance = Instance::mono(cx.tcx, def_id); if let Some(&g) = cx.instances.borrow().get(&instance) { return g; } let defined_in_current_codegen_unit = cx.codegen_unit .items() .contains_key(&MonoItem::Static(def_id)); assert!(!defined_in_current_codegen_unit, "consts::get_static() should always hit the cache for \ statics defined in the same CGU, but did not for `{:?}`", def_id); let ty = instance.ty(cx.tcx); let sym = cx.tcx.symbol_name(instance); let g = if let Some(id) = cx.tcx.hir.as_local_node_id(def_id) { let llty = cx.layout_of(ty).llvm_type(cx); let (g, attrs) = match cx.tcx.hir.get(id) { hir_map::NodeItem(&hir::Item { ref attrs, span, node: hir::ItemStatic(..), .. }) => { if declare::get_declared_value(cx, &sym[..]).is_some() { span_bug!(span, "trans: Conflicting symbol names for static?"); } let g = declare::define_global(cx, &sym[..], llty).unwrap(); if !cx.tcx.is_reachable_non_generic(def_id) { unsafe { llvm::LLVMRustSetVisibility(g, llvm::Visibility::Hidden); } } (g, attrs) } hir_map::NodeForeignItem(&hir::ForeignItem { ref attrs, span, node: hir::ForeignItemStatic(..), .. }) => { let g = if let Some(linkage) = cx.tcx.trans_fn_attrs(def_id).linkage { // If this is a static with a linkage specified, then we need to handle // it a little specially. The typesystem prevents things like &T and // extern "C" fn() from being non-null, so we can't just declare a // static and call it a day. Some linkages (like weak) will make it such // that the static actually has a null value. let llty2 = match ty.sty { ty::TyRawPtr(ref mt) => cx.layout_of(mt.ty).llvm_type(cx), _ => { cx.sess().span_fatal(span, "must have type `*const T` or `*mut T`"); } }; unsafe { // Declare a symbol `foo` with the desired linkage. let g1 = declare::declare_global(cx, &sym, llty2); llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage)); // Declare an internal global `extern_with_linkage_foo` which // is initialized with the address of `foo`. If `foo` is // discarded during linking (for example, if `foo` has weak // linkage and there are no definitions), then // `extern_with_linkage_foo` will instead be initialized to // zero. let mut real_name = "_rust_extern_with_linkage_".to_string(); real_name.push_str(&sym); let g2 = declare::define_global(cx, &real_name, llty).unwrap_or_else(||{ cx.sess().span_fatal(span, &format!("symbol `{}` is already defined", &sym)) }); llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage); llvm::LLVMSetInitializer(g2, g1); g2 } } else { // Generate an external declaration. declare::declare_global(cx, &sym, llty) }; (g, attrs) } item => bug!("get_static: expected static, found {:?}", item) }; for attr in attrs { if attr.check_name("thread_local") { llvm::set_thread_local_mode(g, cx.tls_model); } } g } else { // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow? // FIXME(nagisa): investigate whether it can be changed into define_global let g = declare::declare_global(cx, &sym, cx.layout_of(ty).llvm_type(cx)); // Thread-local statics in some other crate need to *always* be linked // against in a thread-local fashion, so we need to be sure to apply the // thread-local attribute locally if it was present remotely. If we // don't do this then linker errors can be generated where the linker // complains that one object files has a thread local version of the // symbol and another one doesn't. for attr in cx.tcx.get_attrs(def_id).iter() { if attr.check_name("thread_local") { llvm::set_thread_local_mode(g, cx.tls_model); } } if cx.use_dll_storage_attrs && !cx.tcx.is_foreign_item(def_id) { // This item is external but not foreign, i.e. it originates from an external Rust // crate. Since we don't know whether this crate will be linked dynamically or // statically in the final application, we always mark such symbols as 'dllimport'. // If final linkage happens to be static, we rely on compiler-emitted __imp_ stubs to // make things work. // // However, in some scenarios we defer emission of statics to downstream // crates, so there are cases where a static with an upstream DefId // is actually present in the current crate. We can find out via the // is_translated_item query. if !cx.tcx.is_translated_item(def_id) { unsafe { llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport); } } } g }; if cx.use_dll_storage_attrs && cx.tcx.is_dllimport_foreign_item(def_id) { // For foreign (native) libs we know the exact storage type to use. unsafe { llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport); } } cx.instances.borrow_mut().insert(instance, g); cx.statics.borrow_mut().insert(g, def_id); g } pub fn trans_static<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>, def_id: DefId, is_mutable: bool, attrs: &[ast::Attribute]) { unsafe { let g = get_static(cx, def_id); let v = match ::mir::trans_static_initializer(cx, def_id) { Ok(v) => v, // Error has already been reported Err(_) => return, }; // boolean SSA values are i1, but they have to be stored in i8 slots, // otherwise some LLVM optimization passes don't work as expected let mut val_llty = val_ty(v); let v = if val_llty == Type::i1(cx) { val_llty = Type::i8(cx); llvm::LLVMConstZExt(v, val_llty.to_ref()) } else { v }; let instance = Instance::mono(cx.tcx, def_id); let ty = instance.ty(cx.tcx); let llty = cx.layout_of(ty).llvm_type(cx); let g = if val_llty == llty { g } else { // If we created the global with the wrong type, // correct the type. let empty_string = CString::new("").unwrap(); let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g)); let name_string = CString::new(name_str_ref.to_bytes()).unwrap(); llvm::LLVMSetValueName(g, empty_string.as_ptr()); let linkage = llvm::LLVMRustGetLinkage(g); let visibility = llvm::LLVMRustGetVisibility(g); let new_g = llvm::LLVMRustGetOrInsertGlobal( cx.llmod, name_string.as_ptr(), val_llty.to_ref()); llvm::LLVMRustSetLinkage(new_g, linkage); llvm::LLVMRustSetVisibility(new_g, visibility); // To avoid breaking any invariants, we leave around the old // global for the moment; we'll replace all references to it // with the new global later. (See base::trans_crate.) cx.statics_to_rauw.borrow_mut().push((g, new_g)); new_g }; set_global_alignment(cx, g, cx.align_of(ty)); llvm::LLVMSetInitializer(g, v); // As an optimization, all shared statics which do not have interior // mutability are placed into read-only memory. if !is_mutable { if cx.type_is_freeze(ty) { llvm::LLVMSetGlobalConstant(g, llvm::True); } } debuginfo::create_global_var_metadata(cx, def_id, g); if attr::contains_name(attrs, "thread_local") { llvm::set_thread_local_mode(g, cx.tls_model); } base::set_link_section(cx, g, attrs); if attr::contains_name(attrs, "used") { // This static will be stored in the llvm.used variable which is an array of i8* let cast = llvm::LLVMConstPointerCast(g, Type::i8p(cx).to_ref()); cx.used_statics.borrow_mut().push(cast); } } }