]>
Commit | Line | Data |
---|---|---|
9fa01778 | 1 | use crate::base; |
f2b60f7d | 2 | use crate::common::{self, CodegenCx}; |
dfeec247 | 3 | use crate::debuginfo; |
ba9703b0 | 4 | use crate::llvm::{self, True}; |
5e7ed085 | 5 | use crate::llvm_util; |
9fa01778 XL |
6 | use crate::type_::Type; |
7 | use crate::type_of::LayoutLlvmExt; | |
8 | use crate::value::Value; | |
6a06907d | 9 | use cstr::cstr; |
8faf50e0 | 10 | use libc::c_uint; |
dfeec247 | 11 | use rustc_codegen_ssa::traits::*; |
dfeec247 | 12 | use rustc_hir::def_id::DefId; |
ba9703b0 XL |
13 | use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; |
14 | use rustc_middle::mir::interpret::{ | |
5e7ed085 | 15 | read_target_uint, Allocation, ConstAllocation, ErrorHandled, GlobalAlloc, InitChunk, Pointer, |
94222f64 | 16 | Scalar as InterpScalar, |
ba9703b0 XL |
17 | }; |
18 | use rustc_middle::mir::mono::MonoItem; | |
c295e0f8 | 19 | use rustc_middle::ty::layout::LayoutOf; |
ba9703b0 XL |
20 | use rustc_middle::ty::{self, Instance, Ty}; |
21 | use rustc_middle::{bug, span_bug}; | |
94222f64 | 22 | use rustc_target::abi::{ |
c295e0f8 | 23 | AddressSpace, Align, HasDataLayout, Primitive, Scalar, Size, WrappingRange, |
94222f64 XL |
24 | }; |
25 | use std::ops::Range; | |
e9174d1e | 26 | |
5e7ed085 FG |
27 | pub fn const_alloc_to_llvm<'ll>(cx: &CodegenCx<'ll, '_>, alloc: ConstAllocation<'_>) -> &'ll Value { |
28 | let alloc = alloc.inner(); | |
f2b60f7d | 29 | let mut llvals = Vec::with_capacity(alloc.provenance().len() + 1); |
a1dfa0c6 XL |
30 | let dl = cx.data_layout(); |
31 | let pointer_size = dl.pointer_size.bytes() as usize; | |
32 | ||
f2b60f7d FG |
33 | // Note: this function may call `inspect_with_uninit_and_ptr_outside_interpreter`, so `range` |
34 | // must be within the bounds of `alloc` and not contain or overlap a pointer provenance. | |
94222f64 XL |
35 | fn append_chunks_of_init_and_uninit_bytes<'ll, 'a, 'b>( |
36 | llvals: &mut Vec<&'ll Value>, | |
37 | cx: &'a CodegenCx<'ll, 'b>, | |
38 | alloc: &'a Allocation, | |
39 | range: Range<usize>, | |
40 | ) { | |
5e7ed085 | 41 | let chunks = alloc |
94222f64 XL |
42 | .init_mask() |
43 | .range_as_init_chunks(Size::from_bytes(range.start), Size::from_bytes(range.end)); | |
44 | ||
45 | let chunk_to_llval = move |chunk| match chunk { | |
46 | InitChunk::Init(range) => { | |
47 | let range = (range.start.bytes() as usize)..(range.end.bytes() as usize); | |
48 | let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range); | |
49 | cx.const_bytes(bytes) | |
50 | } | |
51 | InitChunk::Uninit(range) => { | |
52 | let len = range.end.bytes() - range.start.bytes(); | |
53 | cx.const_undef(cx.type_array(cx.type_i8(), len)) | |
54 | } | |
55 | }; | |
56 | ||
5e7ed085 FG |
57 | // Generating partially-uninit consts is limited to small numbers of chunks, |
58 | // to avoid the cost of generating large complex const expressions. | |
59 | // For example, `[(u32, u8); 1024 * 1024]` contains uninit padding in each element, | |
60 | // and would result in `{ [5 x i8] zeroinitializer, [3 x i8] undef, ...repeat 1M times... }`. | |
61 | let max = if llvm_util::get_version() < (14, 0, 0) { | |
62 | // Generating partially-uninit consts inhibits optimizations in LLVM < 14. | |
63 | // See https://github.com/rust-lang/rust/issues/84565. | |
64 | 1 | |
65 | } else { | |
064997fb | 66 | cx.sess().opts.unstable_opts.uninit_const_chunk_threshold |
5e7ed085 FG |
67 | }; |
68 | let allow_uninit_chunks = chunks.clone().take(max.saturating_add(1)).count() <= max; | |
94222f64 | 69 | |
5e7ed085 | 70 | if allow_uninit_chunks { |
94222f64 XL |
71 | llvals.extend(chunks.map(chunk_to_llval)); |
72 | } else { | |
5e7ed085 FG |
73 | // If this allocation contains any uninit bytes, codegen as if it was initialized |
74 | // (using some arbitrary value for uninit bytes). | |
75 | let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range); | |
76 | llvals.push(cx.const_bytes(bytes)); | |
94222f64 XL |
77 | } |
78 | } | |
79 | ||
a1dfa0c6 | 80 | let mut next_offset = 0; |
f2b60f7d | 81 | for &(offset, alloc_id) in alloc.provenance().iter() { |
a1dfa0c6 XL |
82 | let offset = offset.bytes(); |
83 | assert_eq!(offset as usize as u64, offset); | |
84 | let offset = offset as usize; | |
85 | if offset > next_offset { | |
f2b60f7d | 86 | // This `inspect` is okay since we have checked that there is no provenance, it |
e1599b0c | 87 | // is within the bounds of the allocation, and it doesn't affect interpreter execution |
94222f64 XL |
88 | // (we inspect the result after interpreter execution). |
89 | append_chunks_of_init_and_uninit_bytes(&mut llvals, cx, alloc, next_offset..offset); | |
a1dfa0c6 XL |
90 | } |
91 | let ptr_offset = read_target_uint( | |
92 | dl.endian, | |
e1599b0c XL |
93 | // This `inspect` is okay since it is within the bounds of the allocation, it doesn't |
94 | // affect interpreter execution (we inspect the result after interpreter execution), | |
f2b60f7d | 95 | // and we properly interpret the provenance as a relocation pointer offset. |
3dfed10e | 96 | alloc.inspect_with_uninit_and_ptr_outside_interpreter(offset..(offset + pointer_size)), |
dfeec247 XL |
97 | ) |
98 | .expect("const_alloc_to_llvm: could not read relocation pointer") | |
99 | as u64; | |
3dfed10e XL |
100 | |
101 | let address_space = match cx.tcx.global_alloc(alloc_id) { | |
102 | GlobalAlloc::Function(..) => cx.data_layout().instruction_address_space, | |
064997fb FG |
103 | GlobalAlloc::Static(..) | GlobalAlloc::Memory(..) | GlobalAlloc::VTable(..) => { |
104 | AddressSpace::DATA | |
105 | } | |
3dfed10e XL |
106 | }; |
107 | ||
a1dfa0c6 | 108 | llvals.push(cx.scalar_to_backend( |
136023e0 XL |
109 | InterpScalar::from_pointer( |
110 | Pointer::new(alloc_id, Size::from_bytes(ptr_offset)), | |
111 | &cx.tcx, | |
112 | ), | |
04454e1e FG |
113 | Scalar::Initialized { |
114 | value: Primitive::Pointer, | |
115 | valid_range: WrappingRange::full(dl.pointer_size), | |
116 | }, | |
3dfed10e | 117 | cx.type_i8p_ext(address_space), |
a1dfa0c6 XL |
118 | )); |
119 | next_offset = offset + pointer_size; | |
1a4d82fc | 120 | } |
e1599b0c XL |
121 | if alloc.len() >= next_offset { |
122 | let range = next_offset..alloc.len(); | |
f2b60f7d | 123 | // This `inspect` is okay since we have check that it is after all provenance, it is |
e1599b0c | 124 | // within the bounds of the allocation, and it doesn't affect interpreter execution (we |
94222f64 XL |
125 | // inspect the result after interpreter execution). |
126 | append_chunks_of_init_and_uninit_bytes(&mut llvals, cx, alloc, range); | |
a1dfa0c6 XL |
127 | } |
128 | ||
129 | cx.const_struct(&llvals, true) | |
1a4d82fc JJ |
130 | } |
131 | ||
a2a8927a | 132 | pub fn codegen_static_initializer<'ll, 'tcx>( |
a1dfa0c6 XL |
133 | cx: &CodegenCx<'ll, 'tcx>, |
134 | def_id: DefId, | |
5e7ed085 | 135 | ) -> Result<(&'ll Value, ConstAllocation<'tcx>), ErrorHandled> { |
1b1a35ee | 136 | let alloc = cx.tcx.eval_static_initializer(def_id)?; |
a1dfa0c6 | 137 | Ok((const_alloc_to_llvm(cx, alloc), alloc)) |
3b2f2976 XL |
138 | } |
139 | ||
a2a8927a | 140 | fn set_global_alignment<'ll>(cx: &CodegenCx<'ll, '_>, gv: &'ll Value, mut align: Align) { |
ea8adc8c XL |
141 | // The target may require greater alignment for globals than the type does. |
142 | // Note: GCC and Clang also allow `__attribute__((aligned))` on variables, | |
143 | // which can force it to be smaller. Rust doesn't support this yet. | |
29967ef6 | 144 | if let Some(min) = cx.sess().target.min_global_align { |
a1dfa0c6 | 145 | match Align::from_bits(min) { |
ff7c6d11 | 146 | Ok(min) => align = align.max(min), |
ea8adc8c | 147 | Err(err) => { |
2c00a5a8 | 148 | cx.sess().err(&format!("invalid minimum global alignment: {}", err)); |
ea8adc8c XL |
149 | } |
150 | } | |
151 | } | |
152 | unsafe { | |
a1dfa0c6 | 153 | llvm::LLVMSetAlignment(gv, align.bytes() as u32); |
ea8adc8c XL |
154 | } |
155 | } | |
156 | ||
a2a8927a | 157 | fn check_and_apply_linkage<'ll, 'tcx>( |
b7449926 | 158 | cx: &CodegenCx<'ll, 'tcx>, |
8faf50e0 XL |
159 | attrs: &CodegenFnAttrs, |
160 | ty: Ty<'tcx>, | |
3dfed10e | 161 | sym: &str, |
f2b60f7d | 162 | def_id: DefId, |
b7449926 | 163 | ) -> &'ll Value { |
8faf50e0 XL |
164 | let llty = cx.layout_of(ty).llvm_type(cx); |
165 | if let Some(linkage) = attrs.linkage { | |
166 | debug!("get_static: sym={} linkage={:?}", sym, linkage); | |
167 | ||
168 | // If this is a static with a linkage specified, then we need to handle | |
169 | // it a little specially. The typesystem prevents things like &T and | |
170 | // extern "C" fn() from being non-null, so we can't just declare a | |
171 | // static and call it a day. Some linkages (like weak) will make it such | |
172 | // that the static actually has a null value. | |
1b1a35ee | 173 | let llty2 = if let ty::RawPtr(ref mt) = ty.kind() { |
0bf4aa26 XL |
174 | cx.layout_of(mt.ty).llvm_type(cx) |
175 | } else { | |
dc9dc135 | 176 | cx.sess().span_fatal( |
f2b60f7d | 177 | cx.tcx.def_span(def_id), |
dfeec247 XL |
178 | "must have type `*const T` or `*mut T` due to `#[linkage]` attribute", |
179 | ) | |
8faf50e0 XL |
180 | }; |
181 | unsafe { | |
182 | // Declare a symbol `foo` with the desired linkage. | |
c295e0f8 | 183 | let g1 = cx.declare_global(sym, llty2); |
8faf50e0 XL |
184 | llvm::LLVMRustSetLinkage(g1, base::linkage_to_llvm(linkage)); |
185 | ||
186 | // Declare an internal global `extern_with_linkage_foo` which | |
187 | // is initialized with the address of `foo`. If `foo` is | |
188 | // discarded during linking (for example, if `foo` has weak | |
189 | // linkage and there are no definitions), then | |
190 | // `extern_with_linkage_foo` will instead be initialized to | |
191 | // zero. | |
192 | let mut real_name = "_rust_extern_with_linkage_".to_string(); | |
c295e0f8 | 193 | real_name.push_str(sym); |
dfeec247 | 194 | let g2 = cx.define_global(&real_name, llty).unwrap_or_else(|| { |
29967ef6 | 195 | cx.sess().span_fatal( |
f2b60f7d | 196 | cx.tcx.def_span(def_id), |
29967ef6 XL |
197 | &format!("symbol `{}` is already defined", &sym), |
198 | ) | |
8faf50e0 XL |
199 | }); |
200 | llvm::LLVMRustSetLinkage(g2, llvm::Linkage::InternalLinkage); | |
201 | llvm::LLVMSetInitializer(g2, g1); | |
202 | g2 | |
203 | } | |
f2b60f7d FG |
204 | } else if cx.tcx.sess.target.arch == "x86" && |
205 | let Some(dllimport) = common::get_dllimport(cx.tcx, def_id, sym) | |
206 | { | |
207 | cx.declare_global(&common::i686_decorated_name(&dllimport, common::is_mingw_gnu_toolchain(&cx.tcx.sess.target), true), llty) | |
8faf50e0 XL |
208 | } else { |
209 | // Generate an external declaration. | |
210 | // FIXME(nagisa): investigate whether it can be changed into define_global | |
c295e0f8 | 211 | cx.declare_global(sym, llty) |
8faf50e0 XL |
212 | } |
213 | } | |
214 | ||
a2a8927a | 215 | pub fn ptrcast<'ll>(val: &'ll Value, ty: &'ll Type) -> &'ll Value { |
dfeec247 | 216 | unsafe { llvm::LLVMConstPointerCast(val, ty) } |
a1dfa0c6 | 217 | } |
c1a9b12d | 218 | |
a2a8927a | 219 | impl<'ll> CodegenCx<'ll, '_> { |
923072b8 | 220 | pub(crate) fn const_bitcast(&self, val: &'ll Value, ty: &'ll Type) -> &'ll Value { |
dfeec247 | 221 | unsafe { llvm::LLVMConstBitCast(val, ty) } |
a1dfa0c6 | 222 | } |
c1a9b12d | 223 | |
923072b8 | 224 | pub(crate) fn static_addr_of_mut( |
a1dfa0c6 XL |
225 | &self, |
226 | cv: &'ll Value, | |
227 | align: Align, | |
228 | kind: Option<&str>, | |
229 | ) -> &'ll Value { | |
230 | unsafe { | |
231 | let gv = match kind { | |
232 | Some(kind) if !self.tcx.sess.fewer_names() => { | |
233 | let name = self.generate_local_symbol_name(kind); | |
a2a8927a | 234 | let gv = self.define_global(&name, self.val_ty(cv)).unwrap_or_else(|| { |
dfeec247 | 235 | bug!("symbol `{}` is already defined", name); |
a1dfa0c6 XL |
236 | }); |
237 | llvm::LLVMRustSetLinkage(gv, llvm::Linkage::PrivateLinkage); | |
238 | gv | |
dfeec247 | 239 | } |
a1dfa0c6 XL |
240 | _ => self.define_private_global(self.val_ty(cv)), |
241 | }; | |
242 | llvm::LLVMSetInitializer(gv, cv); | |
c295e0f8 | 243 | set_global_alignment(self, gv, align); |
ba9703b0 | 244 | llvm::SetUnnamedAddress(gv, llvm::UnnamedAddr::Global); |
a1dfa0c6 XL |
245 | gv |
246 | } | |
247 | } | |
8faf50e0 | 248 | |
923072b8 | 249 | pub(crate) fn get_static(&self, def_id: DefId) -> &'ll Value { |
a1dfa0c6 XL |
250 | let instance = Instance::mono(self.tcx, def_id); |
251 | if let Some(&g) = self.instances.borrow().get(&instance) { | |
252 | return g; | |
253 | } | |
254 | ||
dfeec247 XL |
255 | let defined_in_current_codegen_unit = |
256 | self.codegen_unit.items().contains_key(&MonoItem::Static(def_id)); | |
257 | assert!( | |
258 | !defined_in_current_codegen_unit, | |
259 | "consts::get_static() should always hit the cache for \ | |
a1dfa0c6 | 260 | statics defined in the same CGU, but did not for `{:?}`", |
dfeec247 XL |
261 | def_id |
262 | ); | |
a1dfa0c6 | 263 | |
3dfed10e | 264 | let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all()); |
e74abb32 | 265 | let sym = self.tcx.symbol_name(instance).name; |
5869c6ff | 266 | let fn_attrs = self.tcx.codegen_fn_attrs(def_id); |
a1dfa0c6 | 267 | |
5869c6ff | 268 | debug!("get_static: sym={} instance={:?} fn_attrs={:?}", sym, instance, fn_attrs); |
a1dfa0c6 | 269 | |
5869c6ff | 270 | let g = if def_id.is_local() && !self.tcx.is_foreign_item(def_id) { |
a1dfa0c6 | 271 | let llty = self.layout_of(ty).llvm_type(self); |
5869c6ff XL |
272 | if let Some(g) = self.get_declared_value(sym) { |
273 | if self.val_ty(g) != self.type_ptr_to(llty) { | |
274 | span_bug!(self.tcx.def_span(def_id), "Conflicting types for static"); | |
a1dfa0c6 | 275 | } |
5869c6ff | 276 | } |
a1dfa0c6 | 277 | |
5869c6ff | 278 | let g = self.declare_global(sym, llty); |
a1dfa0c6 | 279 | |
5869c6ff XL |
280 | if !self.tcx.is_reachable_non_generic(def_id) { |
281 | unsafe { | |
282 | llvm::LLVMRustSetVisibility(g, llvm::Visibility::Hidden); | |
a1dfa0c6 XL |
283 | } |
284 | } | |
c1a9b12d | 285 | |
9e0c209e | 286 | g |
c1a9b12d | 287 | } else { |
c295e0f8 | 288 | check_and_apply_linkage(self, fn_attrs, ty, sym, def_id) |
5869c6ff | 289 | }; |
a1dfa0c6 | 290 | |
5869c6ff XL |
291 | // Thread-local statics in some other crate need to *always* be linked |
292 | // against in a thread-local fashion, so we need to be sure to apply the | |
293 | // thread-local attribute locally if it was present remotely. If we | |
294 | // don't do this then linker errors can be generated where the linker | |
295 | // complains that one object files has a thread local version of the | |
296 | // symbol and another one doesn't. | |
297 | if fn_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) { | |
298 | llvm::set_thread_local_mode(g, self.tls_model); | |
299 | } | |
a1dfa0c6 | 300 | |
5869c6ff | 301 | if !def_id.is_local() { |
dfeec247 | 302 | let needs_dll_storage_attr = self.use_dll_storage_attrs && !self.tcx.is_foreign_item(def_id) && |
a1dfa0c6 XL |
303 | // ThinLTO can't handle this workaround in all cases, so we don't |
304 | // emit the attrs. Instead we make them unnecessary by disallowing | |
9fa01778 XL |
305 | // dynamic linking when linker plugin based LTO is enabled. |
306 | !self.tcx.sess.opts.cg.linker_plugin_lto.enabled(); | |
a1dfa0c6 XL |
307 | |
308 | // If this assertion triggers, there's something wrong with commandline | |
309 | // argument validation. | |
dfeec247 XL |
310 | debug_assert!( |
311 | !(self.tcx.sess.opts.cg.linker_plugin_lto.enabled() | |
29967ef6 | 312 | && self.tcx.sess.target.is_like_windows |
dfeec247 XL |
313 | && self.tcx.sess.opts.cg.prefer_dynamic) |
314 | ); | |
a1dfa0c6 XL |
315 | |
316 | if needs_dll_storage_attr { | |
0731742a | 317 | // This item is external but not foreign, i.e., it originates from an external Rust |
a1dfa0c6 XL |
318 | // crate. Since we don't know whether this crate will be linked dynamically or |
319 | // statically in the final application, we always mark such symbols as 'dllimport'. | |
320 | // If final linkage happens to be static, we rely on compiler-emitted __imp_ stubs | |
321 | // to make things work. | |
322 | // | |
323 | // However, in some scenarios we defer emission of statics to downstream | |
324 | // crates, so there are cases where a static with an upstream DefId | |
325 | // is actually present in the current crate. We can find out via the | |
326 | // is_codegened_item query. | |
327 | if !self.tcx.is_codegened_item(def_id) { | |
328 | unsafe { | |
329 | llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport); | |
330 | } | |
331 | } | |
332 | } | |
5869c6ff | 333 | } |
a1dfa0c6 XL |
334 | |
335 | if self.use_dll_storage_attrs && self.tcx.is_dllimport_foreign_item(def_id) { | |
336 | // For foreign (native) libs we know the exact storage type to use. | |
337 | unsafe { | |
338 | llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport); | |
1a4d82fc JJ |
339 | } |
340 | } | |
c1a9b12d | 341 | |
17df50a5 XL |
342 | unsafe { |
343 | if self.should_assume_dso_local(g, true) { | |
344 | llvm::LLVMRustSetDSOLocal(g, true); | |
345 | } | |
346 | } | |
347 | ||
a1dfa0c6 XL |
348 | self.instances.borrow_mut().insert(instance, g); |
349 | g | |
350 | } | |
351 | } | |
352 | ||
a2a8927a | 353 | impl<'ll> StaticMethods for CodegenCx<'ll, '_> { |
dfeec247 | 354 | fn static_addr_of(&self, cv: &'ll Value, align: Align, kind: Option<&str>) -> &'ll Value { |
a1dfa0c6 XL |
355 | if let Some(&gv) = self.const_globals.borrow().get(&cv) { |
356 | unsafe { | |
357 | // Upgrade the alignment in cases where the same constant is used with different | |
358 | // alignment requirements | |
359 | let llalign = align.bytes() as u32; | |
360 | if llalign > llvm::LLVMGetAlignment(gv) { | |
361 | llvm::LLVMSetAlignment(gv, llalign); | |
362 | } | |
94b46f34 | 363 | } |
a1dfa0c6 XL |
364 | return gv; |
365 | } | |
366 | let gv = self.static_addr_of_mut(cv, align, kind); | |
367 | unsafe { | |
368 | llvm::LLVMSetGlobalConstant(gv, True); | |
c1a9b12d | 369 | } |
a1dfa0c6 XL |
370 | self.const_globals.borrow_mut().insert(cv, gv); |
371 | gv | |
372 | } | |
5bcae85e | 373 | |
dfeec247 | 374 | fn codegen_static(&self, def_id: DefId, is_mutable: bool) { |
a1dfa0c6 XL |
375 | unsafe { |
376 | let attrs = self.tcx.codegen_fn_attrs(def_id); | |
377 | ||
5e7ed085 | 378 | let Ok((v, alloc)) = codegen_static_initializer(self, def_id) else { |
a1dfa0c6 | 379 | // Error has already been reported |
5e7ed085 | 380 | return; |
a1dfa0c6 | 381 | }; |
5e7ed085 | 382 | let alloc = alloc.inner(); |
a1dfa0c6 XL |
383 | |
384 | let g = self.get_static(def_id); | |
385 | ||
386 | // boolean SSA values are i1, but they have to be stored in i8 slots, | |
387 | // otherwise some LLVM optimization passes don't work as expected | |
388 | let mut val_llty = self.val_ty(v); | |
389 | let v = if val_llty == self.type_i1() { | |
390 | val_llty = self.type_i8(); | |
391 | llvm::LLVMConstZExt(v, val_llty) | |
392 | } else { | |
393 | v | |
394 | }; | |
395 | ||
396 | let instance = Instance::mono(self.tcx, def_id); | |
3dfed10e | 397 | let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all()); |
a1dfa0c6 XL |
398 | let llty = self.layout_of(ty).llvm_type(self); |
399 | let g = if val_llty == llty { | |
400 | g | |
401 | } else { | |
402 | // If we created the global with the wrong type, | |
403 | // correct the type. | |
60c5eb7d XL |
404 | let name = llvm::get_value_name(g).to_vec(); |
405 | llvm::set_value_name(g, b""); | |
a1dfa0c6 XL |
406 | |
407 | let linkage = llvm::LLVMRustGetLinkage(g); | |
408 | let visibility = llvm::LLVMRustGetVisibility(g); | |
409 | ||
410 | let new_g = llvm::LLVMRustGetOrInsertGlobal( | |
dfeec247 XL |
411 | self.llmod, |
412 | name.as_ptr().cast(), | |
413 | name.len(), | |
414 | val_llty, | |
415 | ); | |
a1dfa0c6 XL |
416 | |
417 | llvm::LLVMRustSetLinkage(new_g, linkage); | |
418 | llvm::LLVMRustSetVisibility(new_g, visibility); | |
419 | ||
04454e1e FG |
420 | // The old global has had its name removed but is returned by |
421 | // get_static since it is in the instance cache. Provide an | |
422 | // alternative lookup that points to the new global so that | |
423 | // global_asm! can compute the correct mangled symbol name | |
424 | // for the global. | |
425 | self.renamed_statics.borrow_mut().insert(def_id, new_g); | |
426 | ||
a1dfa0c6 XL |
427 | // To avoid breaking any invariants, we leave around the old |
428 | // global for the moment; we'll replace all references to it | |
429 | // with the new global later. (See base::codegen_backend.) | |
430 | self.statics_to_rauw.borrow_mut().push((g, new_g)); | |
431 | new_g | |
432 | }; | |
c295e0f8 | 433 | set_global_alignment(self, g, self.align_of(ty)); |
a1dfa0c6 XL |
434 | llvm::LLVMSetInitializer(g, v); |
435 | ||
17df50a5 XL |
436 | if self.should_assume_dso_local(g, true) { |
437 | llvm::LLVMRustSetDSOLocal(g, true); | |
438 | } | |
439 | ||
a1dfa0c6 XL |
440 | // As an optimization, all shared statics which do not have interior |
441 | // mutability are placed into read-only memory. | |
29967ef6 XL |
442 | if !is_mutable && self.type_is_freeze(ty) { |
443 | llvm::LLVMSetGlobalConstant(g, llvm::True); | |
a1dfa0c6 | 444 | } |
5bcae85e | 445 | |
5e7ed085 | 446 | debuginfo::build_global_var_di_node(self, def_id, g); |
a1dfa0c6 XL |
447 | |
448 | if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) { | |
449 | llvm::set_thread_local_mode(g, self.tls_model); | |
450 | ||
451 | // Do not allow LLVM to change the alignment of a TLS on macOS. | |
452 | // | |
453 | // By default a global's alignment can be freely increased. | |
454 | // This allows LLVM to generate more performant instructions | |
0731742a | 455 | // e.g., using load-aligned into a SIMD register. |
a1dfa0c6 XL |
456 | // |
457 | // However, on macOS 10.10 or below, the dynamic linker does not | |
458 | // respect any alignment given on the TLS (radar 24221680). | |
459 | // This will violate the alignment assumption, and causing segfault at runtime. | |
460 | // | |
461 | // This bug is very easy to trigger. In `println!` and `panic!`, | |
462 | // the `LOCAL_STDOUT`/`LOCAL_STDERR` handles are stored in a TLS, | |
463 | // which the values would be `mem::replace`d on initialization. | |
464 | // The implementation of `mem::replace` will use SIMD | |
465 | // whenever the size is 32 bytes or higher. LLVM notices SIMD is used | |
466 | // and tries to align `LOCAL_STDOUT`/`LOCAL_STDERR` to a 32-byte boundary, | |
467 | // which macOS's dyld disregarded and causing crashes | |
468 | // (see issues #51794, #51758, #50867, #48866 and #44056). | |
469 | // | |
470 | // To workaround the bug, we trick LLVM into not increasing | |
471 | // the global's alignment by explicitly assigning a section to it | |
472 | // (equivalent to automatically generating a `#[link_section]` attribute). | |
473 | // See the comment in the `GlobalValue::canIncreaseAlignment()` function | |
474 | // of `lib/IR/Globals.cpp` for why this works. | |
475 | // | |
476 | // When the alignment is not increased, the optimized `mem::replace` | |
477 | // will use load-unaligned instructions instead, and thus avoiding the crash. | |
478 | // | |
479 | // We could remove this hack whenever we decide to drop macOS 10.10 support. | |
29967ef6 | 480 | if self.tcx.sess.target.is_like_osx { |
f2b60f7d | 481 | // The `inspect` method is okay here because we checked for provenance, and |
ba9703b0 XL |
482 | // because we are doing this access to inspect the final interpreter state |
483 | // (not as part of the interpreter execution). | |
484 | // | |
485 | // FIXME: This check requires that the (arbitrary) value of undefined bytes | |
486 | // happens to be zero. Instead, we should only check the value of defined bytes | |
487 | // and set all undefined bytes to zero if this allocation is headed for the | |
488 | // BSS. | |
f2b60f7d | 489 | let all_bytes_are_zero = alloc.provenance().is_empty() |
ba9703b0 | 490 | && alloc |
3dfed10e | 491 | .inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len()) |
e1599b0c | 492 | .iter() |
ba9703b0 XL |
493 | .all(|&byte| byte == 0); |
494 | ||
495 | let sect_name = if all_bytes_are_zero { | |
6a06907d | 496 | cstr!("__DATA,__thread_bss") |
a1dfa0c6 | 497 | } else { |
6a06907d | 498 | cstr!("__DATA,__thread_data") |
a1dfa0c6 XL |
499 | }; |
500 | llvm::LLVMSetSection(g, sect_name.as_ptr()); | |
501 | } | |
502 | } | |
503 | ||
a1dfa0c6 XL |
504 | // Wasm statics with custom link sections get special treatment as they |
505 | // go into custom sections of the wasm executable. | |
3c0e092e | 506 | if self.tcx.sess.target.is_like_wasm { |
a1dfa0c6 XL |
507 | if let Some(section) = attrs.link_section { |
508 | let section = llvm::LLVMMDStringInContext( | |
509 | self.llcx, | |
e74abb32 | 510 | section.as_str().as_ptr().cast(), |
a1dfa0c6 XL |
511 | section.as_str().len() as c_uint, |
512 | ); | |
f2b60f7d | 513 | assert!(alloc.provenance().is_empty()); |
e1599b0c | 514 | |
f2b60f7d | 515 | // The `inspect` method is okay here because we checked for provenance, and |
e1599b0c XL |
516 | // because we are doing this access to inspect the final interpreter state (not |
517 | // as part of the interpreter execution). | |
dfeec247 | 518 | let bytes = |
3dfed10e | 519 | alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len()); |
a1dfa0c6 XL |
520 | let alloc = llvm::LLVMMDStringInContext( |
521 | self.llcx, | |
e74abb32 | 522 | bytes.as_ptr().cast(), |
e1599b0c | 523 | bytes.len() as c_uint, |
a1dfa0c6 XL |
524 | ); |
525 | let data = [section, alloc]; | |
526 | let meta = llvm::LLVMMDNodeInContext(self.llcx, data.as_ptr(), 2); | |
527 | llvm::LLVMAddNamedMetadataOperand( | |
528 | self.llmod, | |
e74abb32 | 529 | "wasm.custom_sections\0".as_ptr().cast(), |
a1dfa0c6 XL |
530 | meta, |
531 | ); | |
532 | } | |
533 | } else { | |
c295e0f8 | 534 | base::set_link_section(g, attrs); |
8faf50e0 | 535 | } |
8faf50e0 | 536 | |
a1dfa0c6 | 537 | if attrs.flags.contains(CodegenFnAttrFlags::USED) { |
5099ac24 FG |
538 | // `USED` and `USED_LINKER` can't be used together. |
539 | assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)); | |
540 | ||
94222f64 XL |
541 | // The semantics of #[used] in Rust only require the symbol to make it into the |
542 | // object file. It is explicitly allowed for the linker to strip the symbol if it | |
064997fb FG |
543 | // is dead, which means we are allowed use `llvm.compiler.used` instead of |
544 | // `llvm.used` here. | |
545 | // | |
94222f64 XL |
546 | // Additionally, https://reviews.llvm.org/D97448 in LLVM 13 started emitting unique |
547 | // sections with SHF_GNU_RETAIN flag for llvm.used symbols, which may trigger bugs | |
064997fb FG |
548 | // in the handling of `.init_array` (the static constructor list) in versions of |
549 | // the gold linker (prior to the one released with binutils 2.36). | |
550 | // | |
551 | // That said, we only ever emit these when compiling for ELF targets, unless | |
552 | // `#[used(compiler)]` is explicitly requested. This is to avoid similar breakage | |
553 | // on other targets, in particular MachO targets have *their* static constructor | |
554 | // lists broken if `llvm.compiler.used` is emitted rather than llvm.used. However, | |
555 | // that check happens when assigning the `CodegenFnAttrFlags` in `rustc_typeck`, | |
556 | // so we don't need to take care of it here. | |
94222f64 | 557 | self.add_compiler_used_global(g); |
a1dfa0c6 | 558 | } |
5099ac24 FG |
559 | if attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) { |
560 | // `USED` and `USED_LINKER` can't be used together. | |
561 | assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED)); | |
562 | ||
563 | self.add_used_global(g); | |
564 | } | |
cc61c64b | 565 | } |
1a4d82fc | 566 | } |
3dfed10e XL |
567 | |
568 | /// Add a global value to a list to be stored in the `llvm.used` variable, an array of i8*. | |
569 | fn add_used_global(&self, global: &'ll Value) { | |
570 | let cast = unsafe { llvm::LLVMConstPointerCast(global, self.type_i8p()) }; | |
571 | self.used_statics.borrow_mut().push(cast); | |
572 | } | |
94222f64 XL |
573 | |
574 | /// Add a global value to a list to be stored in the `llvm.compiler.used` variable, | |
575 | /// an array of i8*. | |
576 | fn add_compiler_used_global(&self, global: &'ll Value) { | |
577 | let cast = unsafe { llvm::LLVMConstPointerCast(global, self.type_i8p()) }; | |
578 | self.compiler_used_statics.borrow_mut().push(cast); | |
579 | } | |
1a4d82fc | 580 | } |