| use gccjit::{GlobalKind, LValue, RValue, ToRValue, Type}; |
| use rustc_codegen_ssa::traits::{BaseTypeMethods, ConstMethods, DerivedTypeMethods, StaticMethods}; |
| use rustc_hir as hir; |
| use rustc_hir::Node; |
| use rustc_middle::{bug, span_bug}; |
| use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; |
| use rustc_middle::mir::mono::MonoItem; |
| use rustc_middle::ty::{self, Instance, Ty}; |
| use rustc_middle::ty::layout::LayoutOf; |
| use rustc_middle::mir::interpret::{self, ConstAllocation, ErrorHandled, Scalar as InterpScalar, read_target_uint}; |
| use rustc_span::Span; |
| use rustc_span::def_id::DefId; |
| use rustc_target::abi::{self, Align, HasDataLayout, Primitive, Size, WrappingRange}; |
| |
| use crate::base; |
| use crate::context::CodegenCx; |
| use crate::errors::LinkageConstOrMutType; |
| use crate::type_of::LayoutGccExt; |
| |
| impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> { |
| pub fn const_bitcast(&self, value: RValue<'gcc>, typ: Type<'gcc>) -> RValue<'gcc> { |
| if value.get_type() == self.bool_type.make_pointer() { |
| if let Some(pointee) = typ.get_pointee() { |
| if pointee.dyncast_vector().is_some() { |
| panic!() |
| } |
| } |
| } |
| // NOTE: since bitcast makes a value non-constant, don't bitcast if not necessary as some |
| // SIMD builtins require a constant value. |
| self.bitcast_if_needed(value, typ) |
| } |
| } |
| |
| impl<'gcc, 'tcx> StaticMethods for CodegenCx<'gcc, 'tcx> { |
| fn static_addr_of(&self, cv: RValue<'gcc>, align: Align, kind: Option<&str>) -> RValue<'gcc> { |
| // TODO(antoyo): implement a proper rvalue comparison in libgccjit instead of doing the |
| // following: |
| for (value, variable) in &*self.const_globals.borrow() { |
| if format!("{:?}", value) == format!("{:?}", cv) { |
| if let Some(global_variable) = self.global_lvalues.borrow().get(variable) { |
| let alignment = align.bits() as i32; |
| if alignment > global_variable.get_alignment() { |
| global_variable.set_alignment(alignment); |
| } |
| } |
| return *variable; |
| } |
| } |
| let global_value = self.static_addr_of_mut(cv, align, kind); |
| #[cfg(feature = "master")] |
| self.global_lvalues.borrow().get(&global_value) |
| .expect("`static_addr_of_mut` did not add the global to `self.global_lvalues`") |
| .global_set_readonly(); |
| self.const_globals.borrow_mut().insert(cv, global_value); |
| global_value |
| } |
| |
| fn codegen_static(&self, def_id: DefId, is_mutable: bool) { |
| let attrs = self.tcx.codegen_fn_attrs(def_id); |
| |
| let value = |
| match codegen_static_initializer(&self, def_id) { |
| Ok((value, _)) => value, |
| // Error has already been reported |
| Err(_) => return, |
| }; |
| |
| let global = self.get_static(def_id); |
| |
| // 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 val_llty = self.val_ty(value); |
| let value = |
| if val_llty == self.type_i1() { |
| unimplemented!(); |
| } |
| else { |
| value |
| }; |
| |
| let instance = Instance::mono(self.tcx, def_id); |
| let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all()); |
| let gcc_type = self.layout_of(ty).gcc_type(self, true); |
| |
| // TODO(antoyo): set alignment. |
| |
| let value = self.bitcast_if_needed(value, gcc_type); |
| global.global_set_initializer_rvalue(value); |
| |
| // As an optimization, all shared statics which do not have interior |
| // mutability are placed into read-only memory. |
| if !is_mutable { |
| if self.type_is_freeze(ty) { |
| #[cfg(feature = "master")] |
| global.global_set_readonly(); |
| } |
| } |
| |
| if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) { |
| // Do not allow LLVM to change the alignment of a TLS on macOS. |
| // |
| // By default a global's alignment can be freely increased. |
| // This allows LLVM to generate more performant instructions |
| // e.g., using load-aligned into a SIMD register. |
| // |
| // However, on macOS 10.10 or below, the dynamic linker does not |
| // respect any alignment given on the TLS (radar 24221680). |
| // This will violate the alignment assumption, and causing segfault at runtime. |
| // |
| // This bug is very easy to trigger. In `println!` and `panic!`, |
| // the `LOCAL_STDOUT`/`LOCAL_STDERR` handles are stored in a TLS, |
| // which the values would be `mem::replace`d on initialization. |
| // The implementation of `mem::replace` will use SIMD |
| // whenever the size is 32 bytes or higher. LLVM notices SIMD is used |
| // and tries to align `LOCAL_STDOUT`/`LOCAL_STDERR` to a 32-byte boundary, |
| // which macOS's dyld disregarded and causing crashes |
| // (see issues #51794, #51758, #50867, #48866 and #44056). |
| // |
| // To workaround the bug, we trick LLVM into not increasing |
| // the global's alignment by explicitly assigning a section to it |
| // (equivalent to automatically generating a `#[link_section]` attribute). |
| // See the comment in the `GlobalValue::canIncreaseAlignment()` function |
| // of `lib/IR/Globals.cpp` for why this works. |
| // |
| // When the alignment is not increased, the optimized `mem::replace` |
| // will use load-unaligned instructions instead, and thus avoiding the crash. |
| // |
| // We could remove this hack whenever we decide to drop macOS 10.10 support. |
| if self.tcx.sess.target.options.is_like_osx { |
| // The `inspect` method is okay here because we checked for provenance, and |
| // because we are doing this access to inspect the final interpreter state |
| // (not as part of the interpreter execution). |
| // |
| // FIXME: This check requires that the (arbitrary) value of undefined bytes |
| // happens to be zero. Instead, we should only check the value of defined bytes |
| // and set all undefined bytes to zero if this allocation is headed for the |
| // BSS. |
| unimplemented!(); |
| } |
| } |
| |
| // Wasm statics with custom link sections get special treatment as they |
| // go into custom sections of the wasm executable. |
| if self.tcx.sess.opts.target_triple.triple().starts_with("wasm32") { |
| if let Some(_section) = attrs.link_section { |
| unimplemented!(); |
| } |
| } else { |
| // TODO(antoyo): set link section. |
| } |
| |
| if attrs.flags.contains(CodegenFnAttrFlags::USED) || attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) { |
| self.add_used_global(global.to_rvalue()); |
| } |
| } |
| |
| /// Add a global value to a list to be stored in the `llvm.used` variable, an array of i8*. |
| fn add_used_global(&self, _global: RValue<'gcc>) { |
| // TODO(antoyo) |
| } |
| |
| fn add_compiler_used_global(&self, _global: RValue<'gcc>) { |
| // TODO(antoyo) |
| } |
| } |
| |
| impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> { |
| pub fn static_addr_of_mut(&self, cv: RValue<'gcc>, align: Align, kind: Option<&str>) -> RValue<'gcc> { |
| let global = |
| match kind { |
| Some(kind) if !self.tcx.sess.fewer_names() => { |
| let name = self.generate_local_symbol_name(kind); |
| // TODO(antoyo): check if it's okay that no link_section is set. |
| |
| let typ = self.val_ty(cv).get_aligned(align.bytes()); |
| let global = self.declare_private_global(&name[..], typ); |
| global |
| } |
| _ => { |
| let typ = self.val_ty(cv).get_aligned(align.bytes()); |
| let global = self.declare_unnamed_global(typ); |
| global |
| }, |
| }; |
| global.global_set_initializer_rvalue(cv); |
| // TODO(antoyo): set unnamed address. |
| let rvalue = global.get_address(None); |
| self.global_lvalues.borrow_mut().insert(rvalue, global); |
| rvalue |
| } |
| |
| pub fn get_static(&self, def_id: DefId) -> LValue<'gcc> { |
| let instance = Instance::mono(self.tcx, def_id); |
| let fn_attrs = self.tcx.codegen_fn_attrs(def_id); |
| if let Some(&global) = self.instances.borrow().get(&instance) { |
| return global; |
| } |
| |
| let defined_in_current_codegen_unit = |
| self.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(self.tcx, ty::ParamEnv::reveal_all()); |
| let sym = self.tcx.symbol_name(instance).name; |
| |
| let global = |
| if let Some(def_id) = def_id.as_local() { |
| let id = self.tcx.hir().local_def_id_to_hir_id(def_id); |
| let llty = self.layout_of(ty).gcc_type(self, true); |
| // FIXME: refactor this to work without accessing the HIR |
| let global = match self.tcx.hir().get(id) { |
| Node::Item(&hir::Item { span, kind: hir::ItemKind::Static(..), .. }) => { |
| if let Some(global) = self.get_declared_value(&sym) { |
| if self.val_ty(global) != self.type_ptr_to(llty) { |
| span_bug!(span, "Conflicting types for static"); |
| } |
| } |
| |
| let is_tls = fn_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL); |
| let global = self.declare_global( |
| &sym, |
| llty, |
| GlobalKind::Exported, |
| is_tls, |
| fn_attrs.link_section, |
| ); |
| |
| if !self.tcx.is_reachable_non_generic(def_id) { |
| // TODO(antoyo): set visibility. |
| } |
| |
| global |
| } |
| |
| Node::ForeignItem(&hir::ForeignItem { |
| span, |
| kind: hir::ForeignItemKind::Static(..), |
| .. |
| }) => { |
| let fn_attrs = self.tcx.codegen_fn_attrs(def_id); |
| check_and_apply_linkage(&self, &fn_attrs, ty, sym, span) |
| } |
| |
| item => bug!("get_static: expected static, found {:?}", item), |
| }; |
| |
| global |
| } |
| else { |
| // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow? |
| //debug!("get_static: sym={} item_attr={:?}", sym, self.tcx.item_attrs(def_id)); |
| |
| let attrs = self.tcx.codegen_fn_attrs(def_id); |
| let span = self.tcx.def_span(def_id); |
| let global = check_and_apply_linkage(&self, &attrs, ty, sym, span); |
| |
| let needs_dll_storage_attr = false; // TODO(antoyo) |
| |
| // If this assertion triggers, there's something wrong with commandline |
| // argument validation. |
| debug_assert!( |
| !(self.tcx.sess.opts.cg.linker_plugin_lto.enabled() |
| && self.tcx.sess.target.options.is_like_msvc |
| && self.tcx.sess.opts.cg.prefer_dynamic) |
| ); |
| |
| if needs_dll_storage_attr { |
| // 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_codegened_item query. |
| if !self.tcx.is_codegened_item(def_id) { |
| unimplemented!(); |
| } |
| } |
| global |
| }; |
| |
| // TODO(antoyo): set dll storage class. |
| |
| self.instances.borrow_mut().insert(instance, global); |
| global |
| } |
| } |
| |
| pub fn const_alloc_to_gcc<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, alloc: ConstAllocation<'tcx>) -> RValue<'gcc> { |
| let alloc = alloc.inner(); |
| let mut llvals = Vec::with_capacity(alloc.provenance().len() + 1); |
| let dl = cx.data_layout(); |
| let pointer_size = dl.pointer_size.bytes() as usize; |
| |
| let mut next_offset = 0; |
| for &(offset, alloc_id) in alloc.provenance().iter() { |
| let offset = offset.bytes(); |
| assert_eq!(offset as usize as u64, offset); |
| let offset = offset as usize; |
| if offset > next_offset { |
| // This `inspect` is okay since we have checked that it is not within a pointer with provenance, it |
| // is within the bounds of the allocation, and it doesn't affect interpreter execution |
| // (we inspect the result after interpreter execution). Any undef byte is replaced with |
| // some arbitrary byte value. |
| // |
| // FIXME: relay undef bytes to codegen as undef const bytes |
| let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(next_offset..offset); |
| llvals.push(cx.const_bytes(bytes)); |
| } |
| let ptr_offset = |
| read_target_uint( dl.endian, |
| // This `inspect` is okay since it is within the bounds of the allocation, it doesn't |
| // affect interpreter execution (we inspect the result after interpreter execution), |
| // and we properly interpret the provenance as a relocation pointer offset. |
| alloc.inspect_with_uninit_and_ptr_outside_interpreter(offset..(offset + pointer_size)), |
| ) |
| .expect("const_alloc_to_llvm: could not read relocation pointer") |
| as u64; |
| llvals.push(cx.scalar_to_backend( |
| InterpScalar::from_pointer( |
| interpret::Pointer::new(alloc_id, Size::from_bytes(ptr_offset)), |
| &cx.tcx, |
| ), |
| abi::Scalar::Initialized { value: Primitive::Pointer, valid_range: WrappingRange::full(dl.pointer_size) }, |
| cx.type_i8p(), |
| )); |
| next_offset = offset + pointer_size; |
| } |
| if alloc.len() >= next_offset { |
| let range = next_offset..alloc.len(); |
| // This `inspect` is okay since we have check that it is after all provenance, it is |
| // within the bounds of the allocation, and it doesn't affect interpreter execution (we |
| // inspect the result after interpreter execution). Any undef byte is replaced with some |
| // arbitrary byte value. |
| // |
| // FIXME: relay undef bytes to codegen as undef const bytes |
| let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range); |
| llvals.push(cx.const_bytes(bytes)); |
| } |
| |
| cx.const_struct(&llvals, true) |
| } |
| |
| pub fn codegen_static_initializer<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, def_id: DefId) -> Result<(RValue<'gcc>, ConstAllocation<'tcx>), ErrorHandled> { |
| let alloc = cx.tcx.eval_static_initializer(def_id)?; |
| Ok((const_alloc_to_gcc(cx, alloc), alloc)) |
| } |
| |
| fn check_and_apply_linkage<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, attrs: &CodegenFnAttrs, ty: Ty<'tcx>, sym: &str, span: Span) -> LValue<'gcc> { |
| let is_tls = attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL); |
| let llty = cx.layout_of(ty).gcc_type(cx, true); |
| if let Some(linkage) = attrs.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 = |
| if let ty::RawPtr(ref mt) = ty.kind() { |
| cx.layout_of(mt.ty).gcc_type(cx, true) |
| } |
| else { |
| cx.sess().emit_fatal(LinkageConstOrMutType { span: span }) |
| }; |
| // Declare a symbol `foo` with the desired linkage. |
| let global1 = cx.declare_global_with_linkage(&sym, llty2, base::global_linkage_to_gcc(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 global2 = cx.define_global(&real_name, llty, is_tls, attrs.link_section); |
| // TODO(antoyo): set linkage. |
| global2.global_set_initializer_rvalue(global1.get_address(None)); |
| // TODO(antoyo): use global_set_initializer() when it will work. |
| global2 |
| } |
| else { |
| // Generate an external declaration. |
| // FIXME(nagisa): investigate whether it can be changed into define_global |
| |
| // 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. |
| cx.declare_global(&sym, llty, GlobalKind::Imported, is_tls, attrs.link_section) |
| } |
| } |
