diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/consts.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/consts.rs | 237 |
1 files changed, 231 insertions, 6 deletions
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs index 0b96b63bc85..a110ecbb75d 100644 --- a/compiler/rustc_codegen_llvm/src/consts.rs +++ b/compiler/rustc_codegen_llvm/src/consts.rs @@ -4,17 +4,19 @@ use rustc_abi::{Align, HasDataLayout, Primitive, Scalar, Size, WrappingRange}; use rustc_codegen_ssa::common; use rustc_codegen_ssa::traits::*; use rustc_hir::LangItem; +use rustc_hir::attrs::Linkage; use rustc_hir::def::DefKind; -use rustc_hir::def_id::DefId; +use rustc_hir::def_id::{DefId, LOCAL_CRATE}; use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs}; use rustc_middle::mir::interpret::{ Allocation, ConstAllocation, ErrorHandled, InitChunk, Pointer, Scalar as InterpScalar, read_target_uint, }; -use rustc_middle::mir::mono::{Linkage, MonoItem}; +use rustc_middle::mir::mono::MonoItem; use rustc_middle::ty::layout::{HasTypingEnv, LayoutOf}; use rustc_middle::ty::{self, Instance}; use rustc_middle::{bug, span_bug}; +use rustc_span::Symbol; use tracing::{debug, instrument, trace}; use crate::common::CodegenCx; @@ -191,8 +193,8 @@ fn check_and_apply_linkage<'ll, 'tcx>( // 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 real_name = + format!("_rust_extern_with_linkage_{:016x}_{sym}", cx.tcx.stable_crate_id(LOCAL_CRATE)); let g2 = cx.define_global(&real_name, llty).unwrap_or_else(|| { cx.sess().dcx().emit_fatal(SymbolAlreadyDefined { span: cx.tcx.def_span(def_id), @@ -330,6 +332,10 @@ impl<'ll> CodegenCx<'ll, '_> { } g + } else if let Some(classname) = fn_attrs.objc_class { + self.get_objc_classref(classname) + } else if let Some(methname) = fn_attrs.objc_selector { + self.get_objc_selref(methname) } else { check_and_apply_linkage(self, fn_attrs, llty, sym, def_id) }; @@ -451,6 +457,8 @@ impl<'ll> CodegenCx<'ll, '_> { self.statics_to_rauw.borrow_mut().push((g, new_g)); new_g }; + + // NOTE: Alignment from attributes has already been applied to the allocation. set_global_alignment(self, g, alloc.align); llvm::set_initializer(g, v); @@ -540,8 +548,225 @@ impl<'ll> CodegenCx<'ll, '_> { /// Add a global value to a list to be stored in the `llvm.compiler.used` variable, /// an array of ptr. - pub(crate) fn add_compiler_used_global(&mut self, global: &'ll Value) { - self.compiler_used_statics.push(global); + pub(crate) fn add_compiler_used_global(&self, global: &'ll Value) { + self.compiler_used_statics.borrow_mut().push(global); + } + + // We do our best here to match what Clang does when compiling Objective-C natively. + // See Clang's `CGObjCCommonMac::CreateCStringLiteral`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L4134 + fn define_objc_classname(&self, classname: &str) -> &'ll Value { + assert_eq!(self.objc_abi_version(), 1); + + let llval = self.null_terminate_const_bytes(classname.as_bytes()); + let llty = self.val_ty(llval); + let sym = self.generate_local_symbol_name("OBJC_CLASS_NAME_"); + let g = self.define_global(&sym, llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", sym); + }); + set_global_alignment(self, g, self.tcx.data_layout.i8_align.abi); + llvm::set_initializer(g, llval); + llvm::set_linkage(g, llvm::Linkage::PrivateLinkage); + llvm::set_section(g, c"__TEXT,__cstring,cstring_literals"); + llvm::LLVMSetGlobalConstant(g, llvm::TRUE); + llvm::LLVMSetUnnamedAddress(g, llvm::UnnamedAddr::Global); + self.add_compiler_used_global(g); + + g + } + + // We do our best here to match what Clang does when compiling Objective-C natively. + // See Clang's `ObjCNonFragileABITypesHelper`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L6052 + fn get_objc_class_t(&self) -> &'ll Type { + if let Some(class_t) = self.objc_class_t.get() { + return class_t; + } + + assert_eq!(self.objc_abi_version(), 2); + + // struct _class_t { + // struct _class_t* isa; + // struct _class_t* const superclass; + // void* cache; + // IMP* vtable; + // struct class_ro_t* ro; + // } + + let class_t = self.type_named_struct("struct._class_t"); + let els = [self.type_ptr(); 5]; + let packed = false; + self.set_struct_body(class_t, &els, packed); + + self.objc_class_t.set(Some(class_t)); + class_t + } + + // We do our best here to match what Clang does when compiling Objective-C natively. We + // deduplicate references within a CGU, but we need a reference definition in each referencing + // CGU. All attempts at using external references to a single reference definition result in + // linker errors. + fn get_objc_classref(&self, classname: Symbol) -> &'ll Value { + let mut classrefs = self.objc_classrefs.borrow_mut(); + if let Some(classref) = classrefs.get(&classname).copied() { + return classref; + } + + let g = match self.objc_abi_version() { + 1 => { + // See Clang's `CGObjCMac::EmitClassRefFromId`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L5205 + let llval = self.define_objc_classname(classname.as_str()); + let llty = self.type_ptr(); + let sym = self.generate_local_symbol_name("OBJC_CLASS_REFERENCES_"); + let g = self.define_global(&sym, llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", sym); + }); + set_global_alignment(self, g, self.tcx.data_layout.pointer_align().abi); + llvm::set_initializer(g, llval); + llvm::set_linkage(g, llvm::Linkage::PrivateLinkage); + llvm::set_section(g, c"__OBJC,__cls_refs,literal_pointers,no_dead_strip"); + self.add_compiler_used_global(g); + g + } + 2 => { + // See Clang's `CGObjCNonFragileABIMac::EmitClassRefFromId`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L7423 + let llval = { + let extern_sym = format!("OBJC_CLASS_$_{}", classname.as_str()); + let extern_llty = self.get_objc_class_t(); + self.declare_global(&extern_sym, extern_llty) + }; + let llty = self.type_ptr(); + let sym = self.generate_local_symbol_name("OBJC_CLASSLIST_REFERENCES_$_"); + let g = self.define_global(&sym, llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", sym); + }); + set_global_alignment(self, g, self.tcx.data_layout.pointer_align().abi); + llvm::set_initializer(g, llval); + llvm::set_linkage(g, llvm::Linkage::InternalLinkage); + llvm::set_section(g, c"__DATA,__objc_classrefs,regular,no_dead_strip"); + self.add_compiler_used_global(g); + g + } + _ => unreachable!(), + }; + + classrefs.insert(classname, g); + g + } + + // We do our best here to match what Clang does when compiling Objective-C natively. We + // deduplicate references within a CGU, but we need a reference definition in each referencing + // CGU. All attempts at using external references to a single reference definition result in + // linker errors. + // + // Newer versions of Apple Clang generate calls to `@"objc_msgSend$methname"` selector stub + // functions. We don't currently do that. The code we generate is closer to what Apple Clang + // generates with the `-fno-objc-msgsend-selector-stubs` option. + fn get_objc_selref(&self, methname: Symbol) -> &'ll Value { + let mut selrefs = self.objc_selrefs.borrow_mut(); + if let Some(selref) = selrefs.get(&methname).copied() { + return selref; + } + + let abi_version = self.objc_abi_version(); + + // See Clang's `CGObjCCommonMac::CreateCStringLiteral`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L4134 + let methname_llval = self.null_terminate_const_bytes(methname.as_str().as_bytes()); + let methname_llty = self.val_ty(methname_llval); + let methname_sym = self.generate_local_symbol_name("OBJC_METH_VAR_NAME_"); + let methname_g = self.define_global(&methname_sym, methname_llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", methname_sym); + }); + set_global_alignment(self, methname_g, self.tcx.data_layout.i8_align.abi); + llvm::set_initializer(methname_g, methname_llval); + llvm::set_linkage(methname_g, llvm::Linkage::PrivateLinkage); + llvm::set_section( + methname_g, + match abi_version { + 1 => c"__TEXT,__cstring,cstring_literals", + 2 => c"__TEXT,__objc_methname,cstring_literals", + _ => unreachable!(), + }, + ); + llvm::LLVMSetGlobalConstant(methname_g, llvm::TRUE); + llvm::LLVMSetUnnamedAddress(methname_g, llvm::UnnamedAddr::Global); + self.add_compiler_used_global(methname_g); + + // See Clang's `CGObjCMac::EmitSelectorAddr`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L5243 + // And Clang's `CGObjCNonFragileABIMac::EmitSelectorAddr`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L7586 + let selref_llval = methname_g; + let selref_llty = self.type_ptr(); + let selref_sym = self.generate_local_symbol_name("OBJC_SELECTOR_REFERENCES_"); + let selref_g = self.define_global(&selref_sym, selref_llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", selref_sym); + }); + set_global_alignment(self, selref_g, self.tcx.data_layout.pointer_align().abi); + llvm::set_initializer(selref_g, selref_llval); + llvm::set_externally_initialized(selref_g, true); + llvm::set_linkage( + selref_g, + match abi_version { + 1 => llvm::Linkage::PrivateLinkage, + 2 => llvm::Linkage::InternalLinkage, + _ => unreachable!(), + }, + ); + llvm::set_section( + selref_g, + match abi_version { + 1 => c"__OBJC,__message_refs,literal_pointers,no_dead_strip", + 2 => c"__DATA,__objc_selrefs,literal_pointers,no_dead_strip", + _ => unreachable!(), + }, + ); + self.add_compiler_used_global(selref_g); + + selrefs.insert(methname, selref_g); + selref_g + } + + // We do our best here to match what Clang does when compiling Objective-C natively. + // See Clang's `ObjCTypesHelper`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L5936 + // And Clang's `CGObjCMac::EmitModuleInfo`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L5151 + pub(crate) fn define_objc_module_info(&mut self) { + assert_eq!(self.objc_abi_version(), 1); + + // struct _objc_module { + // long version; // Hardcoded to 7 in Clang. + // long size; // sizeof(struct _objc_module) + // char* name; // Hardcoded to classname "" in Clang. + // struct _objc_symtab* symtab; // Null without class or category definitions. + // } + + let llty = self.type_named_struct("struct._objc_module"); + let i32_llty = self.type_i32(); + let ptr_llty = self.type_ptr(); + let packed = false; + self.set_struct_body(llty, &[i32_llty, i32_llty, ptr_llty, ptr_llty], packed); + + let version = self.const_uint(i32_llty, 7); + let size = self.const_uint(i32_llty, 16); + let name = self.define_objc_classname(""); + let symtab = self.const_null(ptr_llty); + let llval = crate::common::named_struct(llty, &[version, size, name, symtab]); + + let sym = "OBJC_MODULES"; + let g = self.define_global(&sym, llty).unwrap_or_else(|| { + bug!("symbol `{}` is already defined", sym); + }); + set_global_alignment(self, g, self.tcx.data_layout.pointer_align().abi); + llvm::set_initializer(g, llval); + llvm::set_linkage(g, llvm::Linkage::PrivateLinkage); + llvm::set_section(g, c"__OBJC,__module_info,regular,no_dead_strip"); + + self.add_compiler_used_global(g); } } |