1 // Copyright 2012 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.
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.
12 use back::symbol_names;
14 use llvm::{SetUnnamedAddr};
15 use llvm::{ValueRef, True};
16 use rustc::hir::def_id::DefId;
17 use rustc::hir::map as hir_map;
18 use rustc::middle::const_val::ConstEvalErr;
19 use {debuginfo, machine};
21 use trans_item::TransItem;
22 use common::{self, CrateContext, val_ty};
24 use monomorphize::Instance;
31 use std::ffi::{CStr, CString};
35 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
37 llvm::LLVMConstPointerCast(val, ty.to_ref())
41 pub fn addr_of_mut(ccx: &CrateContext,
43 align: machine::llalign,
47 let name = ccx.generate_local_symbol_name(kind);
48 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
49 bug!("symbol `{}` is already defined", name);
51 llvm::LLVMSetInitializer(gv, cv);
52 llvm::LLVMSetAlignment(gv, align);
53 llvm::LLVMRustSetLinkage(gv, llvm::Linkage::InternalLinkage);
54 SetUnnamedAddr(gv, true);
59 pub fn addr_of(ccx: &CrateContext,
61 align: machine::llalign,
64 if let Some(&gv) = ccx.const_globals().borrow().get(&cv) {
66 // Upgrade the alignment in cases where the same constant is used with different
67 // alignment requirements
68 if align > llvm::LLVMGetAlignment(gv) {
69 llvm::LLVMSetAlignment(gv, align);
74 let gv = addr_of_mut(ccx, cv, align, kind);
76 llvm::LLVMSetGlobalConstant(gv, True);
78 ccx.const_globals().borrow_mut().insert(cv, gv);
82 pub fn get_static(ccx: &CrateContext, def_id: DefId) -> ValueRef {
83 let instance = Instance::mono(ccx.tcx(), def_id);
84 if let Some(&g) = ccx.instances().borrow().get(&instance) {
88 let ty = common::instance_ty(ccx.shared(), &instance);
89 let g = if let Some(id) = ccx.tcx().hir.as_local_node_id(def_id) {
91 let llty = type_of::type_of(ccx, ty);
92 let (g, attrs) = match ccx.tcx().hir.get(id) {
93 hir_map::NodeItem(&hir::Item {
94 ref attrs, span, node: hir::ItemStatic(..), ..
96 let sym = ccx.symbol_cache()
97 .get(TransItem::Static(id));
99 let defined_in_current_codegen_unit = ccx.codegen_unit()
101 .contains_key(&TransItem::Static(id));
102 assert!(!defined_in_current_codegen_unit);
104 if declare::get_declared_value(ccx, &sym[..]).is_some() {
105 span_bug!(span, "trans: Conflicting symbol names for static?");
108 let g = declare::define_global(ccx, &sym[..], llty).unwrap();
113 hir_map::NodeForeignItem(&hir::ForeignItem {
114 ref attrs, span, node: hir::ForeignItemStatic(..), ..
116 let sym = symbol_names::symbol_name(instance, ccx.tcx());
117 let g = if let Some(name) =
118 attr::first_attr_value_str_by_name(&attrs, "linkage") {
119 // If this is a static with a linkage specified, then we need to handle
120 // it a little specially. The typesystem prevents things like &T and
121 // extern "C" fn() from being non-null, so we can't just declare a
122 // static and call it a day. Some linkages (like weak) will make it such
123 // that the static actually has a null value.
124 let linkage = match base::llvm_linkage_by_name(&name.as_str()) {
125 Some(linkage) => linkage,
127 ccx.sess().span_fatal(span, "invalid linkage specified");
130 let llty2 = match ty.sty {
131 ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty),
133 ccx.sess().span_fatal(span, "must have type `*const T` or `*mut T`");
137 // Declare a symbol `foo` with the desired linkage.
138 let g1 = declare::declare_global(ccx, &sym, llty2);
139 llvm::LLVMRustSetLinkage(g1, linkage);
141 // Declare an internal global `extern_with_linkage_foo` which
142 // is initialized with the address of `foo`. If `foo` is
143 // discarded during linking (for example, if `foo` has weak
144 // linkage and there are no definitions), then
145 // `extern_with_linkage_foo` will instead be initialized to
147 let mut real_name = "_rust_extern_with_linkage_".to_string();
148 real_name.push_str(&sym);
149 let g2 = declare::define_global(ccx, &real_name, llty).unwrap_or_else(||{
150 ccx.sess().span_fatal(span,
151 &format!("symbol `{}` is already defined", &sym))
153 llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage);
154 llvm::LLVMSetInitializer(g2, g1);
158 // Generate an external declaration.
159 declare::declare_global(ccx, &sym, llty)
165 item => bug!("get_static: expected static, found {:?}", item)
169 if attr.check_name("thread_local") {
170 llvm::set_thread_local(g, true);
176 let sym = symbol_names::symbol_name(instance, ccx.tcx());
178 // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
179 // FIXME(nagisa): investigate whether it can be changed into define_global
180 let g = declare::declare_global(ccx, &sym, type_of::type_of(ccx, ty));
181 // Thread-local statics in some other crate need to *always* be linked
182 // against in a thread-local fashion, so we need to be sure to apply the
183 // thread-local attribute locally if it was present remotely. If we
184 // don't do this then linker errors can be generated where the linker
185 // complains that one object files has a thread local version of the
186 // symbol and another one doesn't.
187 for attr in ccx.tcx().get_attrs(def_id).iter() {
188 if attr.check_name("thread_local") {
189 llvm::set_thread_local(g, true);
192 if ccx.use_dll_storage_attrs() && !ccx.sess().cstore.is_foreign_item(def_id) {
193 // This item is external but not foreign, i.e. it originates from an external Rust
194 // crate. Since we don't know whether this crate will be linked dynamically or
195 // statically in the final application, we always mark such symbols as 'dllimport'.
196 // If final linkage happens to be static, we rely on compiler-emitted __imp_ stubs to
199 llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
205 if ccx.use_dll_storage_attrs() && ccx.sess().cstore.is_dllimport_foreign_item(def_id) {
206 // For foreign (native) libs we know the exact storage type to use.
208 llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
211 ccx.instances().borrow_mut().insert(instance, g);
212 ccx.statics().borrow_mut().insert(g, def_id);
216 pub fn trans_static<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
219 attrs: &[ast::Attribute])
220 -> Result<ValueRef, ConstEvalErr<'tcx>> {
222 let def_id = ccx.tcx().hir.local_def_id(id);
223 let g = get_static(ccx, def_id);
225 let v = ::mir::trans_static_initializer(ccx, def_id)?;
227 // boolean SSA values are i1, but they have to be stored in i8 slots,
228 // otherwise some LLVM optimization passes don't work as expected
229 let mut val_llty = val_ty(v);
230 let v = if val_llty == Type::i1(ccx) {
231 val_llty = Type::i8(ccx);
232 llvm::LLVMConstZExt(v, val_llty.to_ref())
237 let instance = Instance::mono(ccx.tcx(), def_id);
238 let ty = common::instance_ty(ccx.shared(), &instance);
239 let llty = type_of::type_of(ccx, ty);
240 let g = if val_llty == llty {
243 // If we created the global with the wrong type,
245 let empty_string = CString::new("").unwrap();
246 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
247 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
248 llvm::LLVMSetValueName(g, empty_string.as_ptr());
249 let new_g = llvm::LLVMRustGetOrInsertGlobal(
250 ccx.llmod(), name_string.as_ptr(), val_llty.to_ref());
251 // To avoid breaking any invariants, we leave around the old
252 // global for the moment; we'll replace all references to it
253 // with the new global later. (See base::trans_crate.)
254 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
257 llvm::LLVMSetAlignment(g, ccx.align_of(ty));
258 llvm::LLVMSetInitializer(g, v);
260 // As an optimization, all shared statics which do not have interior
261 // mutability are placed into read-only memory.
262 if m != hir::MutMutable {
263 if ccx.shared().type_is_freeze(ty) {
264 llvm::LLVMSetGlobalConstant(g, llvm::True);
268 debuginfo::create_global_var_metadata(ccx, id, g);
270 if attr::contains_name(attrs,
272 llvm::set_thread_local(g, true);
275 base::set_link_section(ccx, g, attrs);
277 if attr::contains_name(attrs, "used") {
278 // This static will be stored in the llvm.used variable which is an array of i8*
279 let cast = llvm::LLVMConstPointerCast(g, Type::i8p(ccx).to_ref());
280 ccx.used_statics().borrow_mut().push(cast);