diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/base.rs | 24 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/common.rs | 14 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/consts.rs | 226 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/context.rs | 81 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/llvm/mod.rs | 4 |
6 files changed, 342 insertions, 8 deletions
diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs index 9cc5d8dbc21..978134cc32b 100644 --- a/compiler/rustc_codegen_llvm/src/base.rs +++ b/compiler/rustc_codegen_llvm/src/base.rs @@ -109,18 +109,36 @@ pub(crate) fn compile_codegen_unit( attributes::apply_to_llfn(entry, llvm::AttributePlace::Function, &attrs); } + // Define Objective-C module info and module flags. Note, the module info will + // also be added to the `llvm.compiler.used` variable, created later. + // + // These are only necessary when we need the linker to do its Objective-C-specific + // magic. We could theoretically do it unconditionally, but at a slight cost to linker + // performance in the common case where it's unnecessary. + if !cx.objc_classrefs.borrow().is_empty() || !cx.objc_selrefs.borrow().is_empty() { + if cx.objc_abi_version() == 1 { + cx.define_objc_module_info(); + } + cx.add_objc_module_flags(); + } + // Finalize code coverage by injecting the coverage map. Note, the coverage map will // also be added to the `llvm.compiler.used` variable, created next. if cx.sess().instrument_coverage() { cx.coverageinfo_finalize(); } - // Create the llvm.used and llvm.compiler.used variables. + // Create the llvm.used variable. if !cx.used_statics.is_empty() { cx.create_used_variable_impl(c"llvm.used", &cx.used_statics); } - if !cx.compiler_used_statics.is_empty() { - cx.create_used_variable_impl(c"llvm.compiler.used", &cx.compiler_used_statics); + + // Create the llvm.compiler.used variable. + { + let compiler_used_statics = cx.compiler_used_statics.borrow(); + if !compiler_used_statics.is_empty() { + cx.create_used_variable_impl(c"llvm.compiler.used", &compiler_used_statics); + } } // Run replace-all-uses-with for statics that need it. This must diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs index 11b79a7fe68..aa2df46329f 100644 --- a/compiler/rustc_codegen_llvm/src/common.rs +++ b/compiler/rustc_codegen_llvm/src/common.rs @@ -108,6 +108,10 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> { bytes_in_context(self.llcx(), bytes) } + pub(crate) fn null_terminate_const_bytes(&self, bytes: &[u8]) -> &'ll Value { + null_terminate_bytes_in_context(self.llcx(), bytes) + } + pub(crate) fn const_get_elt(&self, v: &'ll Value, idx: u64) -> &'ll Value { unsafe { let idx = c_uint::try_from(idx).expect("LLVMGetAggregateElement index overflow"); @@ -381,6 +385,16 @@ pub(crate) fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> & } } +pub(crate) fn null_terminate_bytes_in_context<'ll>( + llcx: &'ll llvm::Context, + bytes: &[u8], +) -> &'ll Value { + unsafe { + let ptr = bytes.as_ptr() as *const c_char; + llvm::LLVMConstStringInContext2(llcx, ptr, bytes.len(), FALSE) + } +} + pub(crate) fn named_struct<'ll>(ty: &'ll Type, elts: &[&'ll Value]) -> &'ll Value { let len = c_uint::try_from(elts.len()).expect("LLVMConstStructInContext elements len overflow"); unsafe { llvm::LLVMConstNamedStruct(ty, elts.as_ptr(), len) } diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs index dc9bb743560..a110ecbb75d 100644 --- a/compiler/rustc_codegen_llvm/src/consts.rs +++ b/compiler/rustc_codegen_llvm/src/consts.rs @@ -16,6 +16,7 @@ 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; @@ -331,6 +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) }; @@ -543,8 +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); } } diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs index 5f4385c9c6a..4a8ea11a3a8 100644 --- a/compiler/rustc_codegen_llvm/src/context.rs +++ b/compiler/rustc_codegen_llvm/src/context.rs @@ -26,7 +26,7 @@ use rustc_session::config::{ BranchProtection, CFGuard, CFProtection, CrateType, DebugInfo, FunctionReturn, PAuthKey, PacRet, }; use rustc_span::source_map::Spanned; -use rustc_span::{DUMMY_SP, Span}; +use rustc_span::{DUMMY_SP, Span, Symbol}; use rustc_symbol_mangling::mangle_internal_symbol; use rustc_target::spec::{HasTargetSpec, RelocModel, SmallDataThresholdSupport, Target, TlsModel}; use smallvec::SmallVec; @@ -119,7 +119,7 @@ pub(crate) struct FullCx<'ll, 'tcx> { /// Statics that will be placed in the llvm.compiler.used variable /// See <https://llvm.org/docs/LangRef.html#the-llvm-compiler-used-global-variable> for details - pub compiler_used_statics: Vec<&'ll Value>, + pub compiler_used_statics: RefCell<Vec<&'ll Value>>, /// Mapping of non-scalar types to llvm types. pub type_lowering: RefCell<FxHashMap<(Ty<'tcx>, Option<VariantIdx>), &'ll Type>>, @@ -146,6 +146,15 @@ pub(crate) struct FullCx<'ll, 'tcx> { /// `global_asm!` needs to be able to find this new global so that it can /// compute the correct mangled symbol name to insert into the asm. pub renamed_statics: RefCell<FxHashMap<DefId, &'ll Value>>, + + /// Cached Objective-C class type + pub objc_class_t: Cell<Option<&'ll Type>>, + + /// Cache of Objective-C class references + pub objc_classrefs: RefCell<FxHashMap<Symbol, &'ll Value>>, + + /// Cache of Objective-C selector references + pub objc_selrefs: RefCell<FxHashMap<Symbol, &'ll Value>>, } fn to_llvm_tls_model(tls_model: TlsModel) -> llvm::ThreadLocalMode { @@ -615,7 +624,7 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> { const_globals: Default::default(), statics_to_rauw: RefCell::new(Vec::new()), used_statics: Vec::new(), - compiler_used_statics: Vec::new(), + compiler_used_statics: Default::default(), type_lowering: Default::default(), scalar_lltypes: Default::default(), coverage_cx, @@ -626,6 +635,9 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> { intrinsics: Default::default(), local_gen_sym_counter: Cell::new(0), renamed_statics: Default::default(), + objc_class_t: Cell::new(None), + objc_classrefs: Default::default(), + objc_selrefs: Default::default(), }, PhantomData, ) @@ -650,6 +662,69 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> { llvm::set_linkage(g, llvm::Linkage::AppendingLinkage); llvm::set_section(g, c"llvm.metadata"); } + + /// The Objective-C ABI that is used. + /// + /// This corresponds to the `-fobjc-abi-version=` flag in Clang / GCC. + pub(crate) fn objc_abi_version(&self) -> u32 { + assert!(self.tcx.sess.target.is_like_darwin); + if self.tcx.sess.target.arch == "x86" && self.tcx.sess.target.os == "macos" { + // 32-bit x86 macOS uses ABI version 1 (a.k.a. the "fragile ABI"). + 1 + } else { + // All other Darwin-like targets we support use ABI version 2 + // (a.k.a the "non-fragile ABI"). + 2 + } + } + + // We do our best here to match what Clang does when compiling Objective-C natively. + // See Clang's `CGObjCCommonMac::EmitImageInfo`: + // https://github.com/llvm/llvm-project/blob/llvmorg-20.1.8/clang/lib/CodeGen/CGObjCMac.cpp#L5085 + pub(crate) fn add_objc_module_flags(&self) { + let abi_version = self.objc_abi_version(); + + llvm::add_module_flag_u32( + self.llmod, + llvm::ModuleFlagMergeBehavior::Error, + "Objective-C Version", + abi_version, + ); + + llvm::add_module_flag_u32( + self.llmod, + llvm::ModuleFlagMergeBehavior::Error, + "Objective-C Image Info Version", + 0, + ); + + llvm::add_module_flag_str( + self.llmod, + llvm::ModuleFlagMergeBehavior::Error, + "Objective-C Image Info Section", + match abi_version { + 1 => "__OBJC,__image_info,regular", + 2 => "__DATA,__objc_imageinfo,regular,no_dead_strip", + _ => unreachable!(), + }, + ); + + if self.tcx.sess.target.env == "sim" { + llvm::add_module_flag_u32( + self.llmod, + llvm::ModuleFlagMergeBehavior::Error, + "Objective-C Is Simulated", + 1 << 5, + ); + } + + llvm::add_module_flag_u32( + self.llmod, + llvm::ModuleFlagMergeBehavior::Error, + "Objective-C Class Properties", + 1 << 6, + ); + } } impl<'ll> SimpleCx<'ll> { pub(crate) fn get_type_of_global(&self, val: &'ll Value) -> &'ll Type { diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs index 0679f55ab7f..e125aba6afc 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs @@ -1237,6 +1237,7 @@ unsafe extern "C" { pub(crate) safe fn LLVMSetGlobalConstant(GlobalVar: &Value, IsConstant: Bool); pub(crate) safe fn LLVMSetTailCall(CallInst: &Value, IsTailCall: Bool); pub(crate) safe fn LLVMSetTailCallKind(CallInst: &Value, kind: TailCallKind); + pub(crate) safe fn LLVMSetExternallyInitialized(GlobalVar: &Value, IsExtInit: Bool); // Operations on attributes pub(crate) fn LLVMCreateStringAttribute( diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs index d6974e22c85..1115d82fa85 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs @@ -258,6 +258,10 @@ pub(crate) fn set_alignment(llglobal: &Value, align: Align) { } } +pub(crate) fn set_externally_initialized(llglobal: &Value, is_ext_init: bool) { + LLVMSetExternallyInitialized(llglobal, is_ext_init.to_llvm_bool()); +} + /// Get the `name`d comdat from `llmod` and assign it to `llglobal`. /// /// Inserts the comdat into `llmod` if it does not exist. |