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