src/librustc_trans/debuginfo/mod.rs - third_party/rust - Git at Google

 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 // See doc.rs for documentation.
 mod doc;

 use self::VariableAccess::*;
 use self::VariableKind::*;

 use self::utils::{DIB, span_start, create_DIArray, is_node_local_to_unit};
 use self::namespace::mangled_name_of_instance;
 use self::type_names::compute_debuginfo_type_name;
 use self::metadata::{type_metadata, file_metadata, TypeMap};
 use self::source_loc::InternalDebugLocation::{self, UnknownLocation};

 use llvm;
 use llvm::{ModuleRef, ContextRef, ValueRef};
 use llvm::debuginfo::{DIFile, DIType, DIScope, DIBuilderRef, DISubprogram, DIArray, DIFlags};
 use rustc::hir::def_id::{DefId, CrateNum};
 use rustc::ty::subst::Substs;

 use abi::Abi;
 use common::CodegenCx;
 use builder::Builder;
 use monomorphize::Instance;
 use rustc::ty::{self, Ty};
 use rustc::mir;
 use rustc::session::config::{self, FullDebugInfo, LimitedDebugInfo, NoDebugInfo};
 use rustc::util::nodemap::{DefIdMap, FxHashMap, FxHashSet};

 use libc::c_uint;
 use std::cell::{Cell, RefCell};
 use std::ffi::CString;
 use std::ptr;

 use syntax_pos::{self, Span, Pos};
 use syntax::ast;
 use syntax::symbol::Symbol;
 use rustc::ty::layout::{self, LayoutOf};

 pub mod gdb;
 mod utils;
 mod namespace;
 mod type_names;
 pub mod metadata;
 mod create_scope_map;
 mod source_loc;

 pub use self::create_scope_map::{create_mir_scopes, MirDebugScope};
 pub use self::source_loc::start_emitting_source_locations;
 pub use self::metadata::create_global_var_metadata;
 pub use self::metadata::create_vtable_metadata;
 pub use self::metadata::extend_scope_to_file;
 pub use self::source_loc::set_source_location;

 #[allow(non_upper_case_globals)]
 const DW_TAG_auto_variable: c_uint = 0x100;
 #[allow(non_upper_case_globals)]
 const DW_TAG_arg_variable: c_uint = 0x101;

 /// A context object for maintaining all state needed by the debuginfo module.
 pub struct CrateDebugContext<'tcx> {
     llcontext: ContextRef,
     llmod: ModuleRef,
     builder: DIBuilderRef,
     created_files: RefCell<FxHashMap<(Symbol, Symbol), DIFile>>,
     created_enum_disr_types: RefCell<FxHashMap<(DefId, layout::Primitive), DIType>>,

     type_map: RefCell<TypeMap<'tcx>>,
     namespace_map: RefCell<DefIdMap<DIScope>>,

     // This collection is used to assert that composite types (structs, enums,
     // ...) have their members only set once:
     composite_types_completed: RefCell<FxHashSet<DIType>>,
 }

 impl<'tcx> CrateDebugContext<'tcx> {
     pub fn new(llmod: ModuleRef) -> CrateDebugContext<'tcx> {
         debug!("CrateDebugContext::new");
         let builder = unsafe { llvm::LLVMRustDIBuilderCreate(llmod) };
         // DIBuilder inherits context from the module, so we'd better use the same one
         let llcontext = unsafe { llvm::LLVMGetModuleContext(llmod) };
         CrateDebugContext {
             llcontext,
             llmod,
             builder,
             created_files: RefCell::new(FxHashMap()),
             created_enum_disr_types: RefCell::new(FxHashMap()),
             type_map: RefCell::new(TypeMap::new()),
             namespace_map: RefCell::new(DefIdMap()),
             composite_types_completed: RefCell::new(FxHashSet()),
         }
     }
 }

 pub enum FunctionDebugContext {
     RegularContext(FunctionDebugContextData),
     DebugInfoDisabled,
     FunctionWithoutDebugInfo,
 }

 impl FunctionDebugContext {
     pub fn get_ref<'a>(&'a self, span: Span) -> &'a FunctionDebugContextData {
         match *self {
             FunctionDebugContext::RegularContext(ref data) => data,
             FunctionDebugContext::DebugInfoDisabled => {
                 span_bug!(span, "{}", FunctionDebugContext::debuginfo_disabled_message());
             }
             FunctionDebugContext::FunctionWithoutDebugInfo => {
                 span_bug!(span, "{}", FunctionDebugContext::should_be_ignored_message());
             }
         }
     }

     fn debuginfo_disabled_message() -> &'static str {
         "debuginfo: Error trying to access FunctionDebugContext although debug info is disabled!"
     }

     fn should_be_ignored_message() -> &'static str {
         "debuginfo: Error trying to access FunctionDebugContext for function that should be \
          ignored by debug info!"
     }
 }

 pub struct FunctionDebugContextData {
     fn_metadata: DISubprogram,
     source_locations_enabled: Cell<bool>,
     pub defining_crate: CrateNum,
 }

 pub enum VariableAccess<'a> {
     // The llptr given is an alloca containing the variable's value
     DirectVariable { alloca: ValueRef },
     // The llptr given is an alloca containing the start of some pointer chain
     // leading to the variable's content.
     IndirectVariable { alloca: ValueRef, address_operations: &'a [i64] }
 }

 pub enum VariableKind {
     ArgumentVariable(usize /*index*/),
     LocalVariable,
     CapturedVariable,
 }

 /// Create any deferred debug metadata nodes
 pub fn finalize(cx: &CodegenCx) {
     if cx.dbg_cx.is_none() {
         return;
     }

     debug!("finalize");

     if gdb::needs_gdb_debug_scripts_section(cx) {
         // Add a .debug_gdb_scripts section to this compile-unit. This will
         // cause GDB to try and load the gdb_load_rust_pretty_printers.py file,
         // which activates the Rust pretty printers for binary this section is
         // contained in.
         gdb::get_or_insert_gdb_debug_scripts_section_global(cx);
     }

     unsafe {
         llvm::LLVMRustDIBuilderFinalize(DIB(cx));
         llvm::LLVMRustDIBuilderDispose(DIB(cx));
         // Debuginfo generation in LLVM by default uses a higher
         // version of dwarf than macOS currently understands. We can
         // instruct LLVM to emit an older version of dwarf, however,
         // for macOS to understand. For more info see #11352
         // This can be overridden using --llvm-opts -dwarf-version,N.
         // Android has the same issue (#22398)
         if cx.sess().target.target.options.is_like_osx ||
            cx.sess().target.target.options.is_like_android {
             llvm::LLVMRustAddModuleFlag(cx.llmod,
                                         "Dwarf Version\0".as_ptr() as *const _,
                                         2)
         }

         // Indicate that we want CodeView debug information on MSVC
         if cx.sess().target.target.options.is_like_msvc {
             llvm::LLVMRustAddModuleFlag(cx.llmod,
                                         "CodeView\0".as_ptr() as *const _,
                                         1)
         }

         // Prevent bitcode readers from deleting the debug info.
         let ptr = "Debug Info Version\0".as_ptr();
         llvm::LLVMRustAddModuleFlag(cx.llmod, ptr as *const _,
                                     llvm::LLVMRustDebugMetadataVersion());
     };
 }

 /// Creates the function-specific debug context.
 ///
 /// Returns the FunctionDebugContext for the function which holds state needed
 /// for debug info creation. The function may also return another variant of the
 /// FunctionDebugContext enum which indicates why no debuginfo should be created
 /// for the function.
 pub fn create_function_debug_context<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                                instance: Instance<'tcx>,
                                                sig: ty::FnSig<'tcx>,
                                                llfn: ValueRef,
                                                mir: &mir::Mir) -> FunctionDebugContext {
     if cx.sess().opts.debuginfo == NoDebugInfo {
         return FunctionDebugContext::DebugInfoDisabled;
     }

     for attr in instance.def.attrs(cx.tcx).iter() {
         if attr.check_name("no_debug") {
             return FunctionDebugContext::FunctionWithoutDebugInfo;
         }
     }

     let containing_scope = get_containing_scope(cx, instance);
     let span = mir.span;

     // This can be the case for functions inlined from another crate
     if span == syntax_pos::DUMMY_SP {
         // FIXME(simulacrum): Probably can't happen; remove.
         return FunctionDebugContext::FunctionWithoutDebugInfo;
     }

     let def_id = instance.def_id();
     let loc = span_start(cx, span);
     let file_metadata = file_metadata(cx, &loc.file.name, def_id.krate);

     let function_type_metadata = unsafe {
         let fn_signature = get_function_signature(cx, sig);
         llvm::LLVMRustDIBuilderCreateSubroutineType(DIB(cx), file_metadata, fn_signature)
     };

     // Find the enclosing function, in case this is a closure.
     let def_key = cx.tcx.def_key(def_id);
     let mut name = def_key.disambiguated_data.data.to_string();

     let enclosing_fn_def_id = cx.tcx.closure_base_def_id(def_id);

     // Get_template_parameters() will append a `<...>` clause to the function
     // name if necessary.
     let generics = cx.tcx.generics_of(enclosing_fn_def_id);
     let substs = instance.substs.truncate_to(cx.tcx, generics);
     let template_parameters = get_template_parameters(cx,
                                                       &generics,
                                                       substs,
                                                       file_metadata,
                                                       &mut name);

     // Get the linkage_name, which is just the symbol name
     let linkage_name = mangled_name_of_instance(cx, instance);

     let scope_line = span_start(cx, span).line;

     let local_id = cx.tcx.hir.as_local_node_id(instance.def_id());
     let is_local_to_unit = local_id.map_or(false, |id| is_node_local_to_unit(cx, id));

     let function_name = CString::new(name).unwrap();
     let linkage_name = CString::new(linkage_name.to_string()).unwrap();

     let mut flags = DIFlags::FlagPrototyped;
     match *cx.sess().entry_fn.borrow() {
         Some((id, _)) => {
             if local_id == Some(id) {
                 flags = flags | DIFlags::FlagMainSubprogram;
             }
         }
         None => {}
     };

     let fn_metadata = unsafe {
         llvm::LLVMRustDIBuilderCreateFunction(
             DIB(cx),
             containing_scope,
             function_name.as_ptr(),
             linkage_name.as_ptr(),
             file_metadata,
             loc.line as c_uint,
             function_type_metadata,
             is_local_to_unit,
             true,
             scope_line as c_uint,
             flags,
             cx.sess().opts.optimize != config::OptLevel::No,
             llfn,
             template_parameters,
             ptr::null_mut())
     };

     // Initialize fn debug context (including scope map and namespace map)
     let fn_debug_context = FunctionDebugContextData {
         fn_metadata,
         source_locations_enabled: Cell::new(false),
         defining_crate: def_id.krate,
     };

     return FunctionDebugContext::RegularContext(fn_debug_context);

     fn get_function_signature<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                         sig: ty::FnSig<'tcx>) -> DIArray {
         if cx.sess().opts.debuginfo == LimitedDebugInfo {
             return create_DIArray(DIB(cx), &[]);
         }

         let mut signature = Vec::with_capacity(sig.inputs().len() + 1);

         // Return type -- llvm::DIBuilder wants this at index 0
         signature.push(match sig.output().sty {
             ty::TyTuple(ref tys, _) if tys.is_empty() => ptr::null_mut(),
             _ => type_metadata(cx, sig.output(), syntax_pos::DUMMY_SP)
         });

         let inputs = if sig.abi == Abi::RustCall {
             &sig.inputs()[..sig.inputs().len() - 1]
         } else {
             sig.inputs()
         };

         // Arguments types
         if cx.sess().target.target.options.is_like_msvc {
             // FIXME(#42800):
             // There is a bug in MSDIA that leads to a crash when it encounters
             // a fixed-size array of `u8` or something zero-sized in a
             // function-type (see #40477).
             // As a workaround, we replace those fixed-size arrays with a
             // pointer-type. So a function `fn foo(a: u8, b: [u8; 4])` would
             // appear as `fn foo(a: u8, b: *const u8)` in debuginfo,
             // and a function `fn bar(x: [(); 7])` as `fn bar(x: *const ())`.
             // This transformed type is wrong, but these function types are
             // already inaccurate due to ABI adjustments (see #42800).
             signature.extend(inputs.iter().map(|&t| {
                 let t = match t.sty {
                     ty::TyArray(ct, _)
                         if (ct == cx.tcx.types.u8) || cx.layout_of(ct).is_zst() => {
                         cx.tcx.mk_imm_ptr(ct)
                     }
                     _ => t
                 };
                 type_metadata(cx, t, syntax_pos::DUMMY_SP)
             }));
         } else {
             signature.extend(inputs.iter().map(|t| {
                 type_metadata(cx, t, syntax_pos::DUMMY_SP)
             }));
         }

         if sig.abi == Abi::RustCall && !sig.inputs().is_empty() {
             if let ty::TyTuple(args, _) = sig.inputs()[sig.inputs().len() - 1].sty {
                 for &argument_type in args {
                     signature.push(type_metadata(cx, argument_type, syntax_pos::DUMMY_SP));
                 }
             }
         }

         return create_DIArray(DIB(cx), &signature[..]);
     }

     fn get_template_parameters<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                          generics: &ty::Generics,
                                          substs: &Substs<'tcx>,
                                          file_metadata: DIFile,
                                          name_to_append_suffix_to: &mut String)
                                          -> DIArray
     {
         if substs.types().next().is_none() {
             return create_DIArray(DIB(cx), &[]);
         }

         name_to_append_suffix_to.push('<');
         for (i, actual_type) in substs.types().enumerate() {
             if i != 0 {
                 name_to_append_suffix_to.push_str(",");
             }

             let actual_type = cx.tcx.fully_normalize_associated_types_in(&actual_type);
             // Add actual type name to <...> clause of function name
             let actual_type_name = compute_debuginfo_type_name(cx,
                                                                actual_type,
                                                                true);
             name_to_append_suffix_to.push_str(&actual_type_name[..]);
         }
         name_to_append_suffix_to.push('>');

         // Again, only create type information if full debuginfo is enabled
         let template_params: Vec<_> = if cx.sess().opts.debuginfo == FullDebugInfo {
             let names = get_type_parameter_names(cx, generics);
             substs.types().zip(names).map(|(ty, name)| {
                 let actual_type = cx.tcx.fully_normalize_associated_types_in(&ty);
                 let actual_type_metadata = type_metadata(cx, actual_type, syntax_pos::DUMMY_SP);
                 let name = CString::new(name.as_str().as_bytes()).unwrap();
                 unsafe {
                     llvm::LLVMRustDIBuilderCreateTemplateTypeParameter(
                         DIB(cx),
                         ptr::null_mut(),
                         name.as_ptr(),
                         actual_type_metadata,
                         file_metadata,
                         0,
                         0)
                 }
             }).collect()
         } else {
             vec![]
         };

         return create_DIArray(DIB(cx), &template_params[..]);
     }

     fn get_type_parameter_names(cx: &CodegenCx, generics: &ty::Generics) -> Vec<ast::Name> {
         let mut names = generics.parent.map_or(vec![], |def_id| {
             get_type_parameter_names(cx, cx.tcx.generics_of(def_id))
         });
         names.extend(generics.types.iter().map(|param| param.name));
         names
     }

     fn get_containing_scope<'cx, 'tcx>(cx: &CodegenCx<'cx, 'tcx>,
                                         instance: Instance<'tcx>)
                                         -> DIScope {
         // First, let's see if this is a method within an inherent impl. Because
         // if yes, we want to make the result subroutine DIE a child of the
         // subroutine's self-type.
         let self_type = cx.tcx.impl_of_method(instance.def_id()).and_then(|impl_def_id| {
             // If the method does *not* belong to a trait, proceed
             if cx.tcx.trait_id_of_impl(impl_def_id).is_none() {
                 let impl_self_ty = cx.tcx.trans_impl_self_ty(impl_def_id, instance.substs);

                 // Only "class" methods are generally understood by LLVM,
                 // so avoid methods on other types (e.g. `<*mut T>::null`).
                 match impl_self_ty.sty {
                     ty::TyAdt(def, ..) if !def.is_box() => {
                         Some(type_metadata(cx, impl_self_ty, syntax_pos::DUMMY_SP))
                     }
                     _ => None
                 }
             } else {
                 // For trait method impls we still use the "parallel namespace"
                 // strategy
                 None
             }
         });

         self_type.unwrap_or_else(|| {
             namespace::item_namespace(cx, DefId {
                 krate: instance.def_id().krate,
                 index: cx.tcx
                          .def_key(instance.def_id())
                          .parent
                          .expect("get_containing_scope: missing parent?")
             })
         })
     }
 }

 pub fn declare_local<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
                                dbg_context: &FunctionDebugContext,
                                variable_name: ast::Name,
                                variable_type: Ty<'tcx>,
                                scope_metadata: DIScope,
                                variable_access: VariableAccess,
                                variable_kind: VariableKind,
                                span: Span) {
     let cx = bx.cx;

     let file = span_start(cx, span).file;
     let file_metadata = file_metadata(cx,
                                       &file.name,
                                       dbg_context.get_ref(span).defining_crate);

     let loc = span_start(cx, span);
     let type_metadata = type_metadata(cx, variable_type, span);

     let (argument_index, dwarf_tag) = match variable_kind {
         ArgumentVariable(index) => (index as c_uint, DW_TAG_arg_variable),
         LocalVariable    |
         CapturedVariable => (0, DW_TAG_auto_variable)
     };
     let align = cx.align_of(variable_type);

     let name = CString::new(variable_name.as_str().as_bytes()).unwrap();
     match (variable_access, &[][..]) {
         (DirectVariable { alloca }, address_operations) |
         (IndirectVariable {alloca, address_operations}, _) => {
             let metadata = unsafe {
                 llvm::LLVMRustDIBuilderCreateVariable(
                     DIB(cx),
                     dwarf_tag,
                     scope_metadata,
                     name.as_ptr(),
                     file_metadata,
                     loc.line as c_uint,
                     type_metadata,
                     cx.sess().opts.optimize != config::OptLevel::No,
                     DIFlags::FlagZero,
                     argument_index,
                     align.abi() as u32,
                 )
             };
             source_loc::set_debug_location(bx,
                 InternalDebugLocation::new(scope_metadata, loc.line, loc.col.to_usize()));
             unsafe {
                 let debug_loc = llvm::LLVMGetCurrentDebugLocation(bx.llbuilder);
                 let instr = llvm::LLVMRustDIBuilderInsertDeclareAtEnd(
                     DIB(cx),
                     alloca,
                     metadata,
                     address_operations.as_ptr(),
                     address_operations.len() as c_uint,
                     debug_loc,
                     bx.llbb());

                 llvm::LLVMSetInstDebugLocation(bx.llbuilder, instr);
             }
         }
     }

     match variable_kind {
         ArgumentVariable(_) | CapturedVariable => {
             assert!(!dbg_context.get_ref(span).source_locations_enabled.get());
             source_loc::set_debug_location(bx, UnknownLocation);
         }
         _ => { /* nothing to do */ }
     }
 }
	// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	// See doc.rs for documentation.
	mod doc;

	use self::VariableAccess::*;
	use self::VariableKind::*;

	use self::utils::{DIB, span_start, create_DIArray, is_node_local_to_unit};
	use self::namespace::mangled_name_of_instance;
	use self::type_names::compute_debuginfo_type_name;
	use self::metadata::{type_metadata, file_metadata, TypeMap};
	use self::source_loc::InternalDebugLocation::{self, UnknownLocation};

	use llvm;
	use llvm::{ModuleRef, ContextRef, ValueRef};
	use llvm::debuginfo::{DIFile, DIType, DIScope, DIBuilderRef, DISubprogram, DIArray, DIFlags};
	use rustc::hir::def_id::{DefId, CrateNum};
	use rustc::ty::subst::Substs;

	use abi::Abi;
	use common::CodegenCx;
	use builder::Builder;
	use monomorphize::Instance;
	use rustc::ty::{self, Ty};
	use rustc::mir;
	use rustc::session::config::{self, FullDebugInfo, LimitedDebugInfo, NoDebugInfo};
	use rustc::util::nodemap::{DefIdMap, FxHashMap, FxHashSet};

	use libc::c_uint;
	use std::cell::{Cell, RefCell};
	use std::ffi::CString;
	use std::ptr;

	use syntax_pos::{self, Span, Pos};
	use syntax::ast;
	use syntax::symbol::Symbol;
	use rustc::ty::layout::{self, LayoutOf};

	pub mod gdb;
	mod utils;
	mod namespace;
	mod type_names;
	pub mod metadata;
	mod create_scope_map;
	mod source_loc;

	pub use self::create_scope_map::{create_mir_scopes, MirDebugScope};
	pub use self::source_loc::start_emitting_source_locations;
	pub use self::metadata::create_global_var_metadata;
	pub use self::metadata::create_vtable_metadata;
	pub use self::metadata::extend_scope_to_file;
	pub use self::source_loc::set_source_location;

	#[allow(non_upper_case_globals)]
	const DW_TAG_auto_variable: c_uint = 0x100;
	#[allow(non_upper_case_globals)]
	const DW_TAG_arg_variable: c_uint = 0x101;

	/// A context object for maintaining all state needed by the debuginfo module.
	pub struct CrateDebugContext<'tcx> {
	llcontext: ContextRef,
	llmod: ModuleRef,
	builder: DIBuilderRef,
	created_files: RefCell<FxHashMap<(Symbol, Symbol), DIFile>>,
	created_enum_disr_types: RefCell<FxHashMap<(DefId, layout::Primitive), DIType>>,

	type_map: RefCell<TypeMap<'tcx>>,
	namespace_map: RefCell<DefIdMap<DIScope>>,

	// This collection is used to assert that composite types (structs, enums,
	// ...) have their members only set once:
	composite_types_completed: RefCell<FxHashSet<DIType>>,
	}

	impl<'tcx> CrateDebugContext<'tcx> {
	pub fn new(llmod: ModuleRef) -> CrateDebugContext<'tcx> {
	debug!("CrateDebugContext::new");
	let builder = unsafe { llvm::LLVMRustDIBuilderCreate(llmod) };
	// DIBuilder inherits context from the module, so we'd better use the same one
	let llcontext = unsafe { llvm::LLVMGetModuleContext(llmod) };
	CrateDebugContext {
	llcontext,
	llmod,
	builder,
	created_files: RefCell::new(FxHashMap()),
	created_enum_disr_types: RefCell::new(FxHashMap()),
	type_map: RefCell::new(TypeMap::new()),
	namespace_map: RefCell::new(DefIdMap()),
	composite_types_completed: RefCell::new(FxHashSet()),
	}
	}
	}

	pub enum FunctionDebugContext {
	RegularContext(FunctionDebugContextData),
	DebugInfoDisabled,
	FunctionWithoutDebugInfo,
	}

	impl FunctionDebugContext {
	pub fn get_ref<'a>(&'a self, span: Span) -> &'a FunctionDebugContextData {
	match *self {
	FunctionDebugContext::RegularContext(ref data) => data,
	FunctionDebugContext::DebugInfoDisabled => {
	span_bug!(span, "{}", FunctionDebugContext::debuginfo_disabled_message());
	}
	FunctionDebugContext::FunctionWithoutDebugInfo => {
	span_bug!(span, "{}", FunctionDebugContext::should_be_ignored_message());
	}
	}
	}

	fn debuginfo_disabled_message() -> &'static str {
	"debuginfo: Error trying to access FunctionDebugContext although debug info is disabled!"
	}

	fn should_be_ignored_message() -> &'static str {
	"debuginfo: Error trying to access FunctionDebugContext for function that should be \
	ignored by debug info!"
	}
	}

	pub struct FunctionDebugContextData {
	fn_metadata: DISubprogram,
	source_locations_enabled: Cell<bool>,
	pub defining_crate: CrateNum,
	}

	pub enum VariableAccess<'a> {
	// The llptr given is an alloca containing the variable's value
	DirectVariable { alloca: ValueRef },
	// The llptr given is an alloca containing the start of some pointer chain
	// leading to the variable's content.
	IndirectVariable { alloca: ValueRef, address_operations: &'a [i64] }
	}

	pub enum VariableKind {
	ArgumentVariable(usize /index/),
	LocalVariable,
	CapturedVariable,
	}

	/// Create any deferred debug metadata nodes
	pub fn finalize(cx: &CodegenCx) {
	if cx.dbg_cx.is_none() {
	return;
	}

	debug!("finalize");

	if gdb::needs_gdb_debug_scripts_section(cx) {
	// Add a .debug_gdb_scripts section to this compile-unit. This will
	// cause GDB to try and load the gdb_load_rust_pretty_printers.py file,
	// which activates the Rust pretty printers for binary this section is
	// contained in.
	gdb::get_or_insert_gdb_debug_scripts_section_global(cx);
	}

	unsafe {
	llvm::LLVMRustDIBuilderFinalize(DIB(cx));
	llvm::LLVMRustDIBuilderDispose(DIB(cx));
	// Debuginfo generation in LLVM by default uses a higher
	// version of dwarf than macOS currently understands. We can
	// instruct LLVM to emit an older version of dwarf, however,
	// for macOS to understand. For more info see #11352
	// This can be overridden using --llvm-opts -dwarf-version,N.
	// Android has the same issue (#22398)
	if cx.sess().target.target.options.is_like_osx \|\|
	cx.sess().target.target.options.is_like_android {
	llvm::LLVMRustAddModuleFlag(cx.llmod,
	"Dwarf Version\0".as_ptr() as *const _,
	2)
	}

	// Indicate that we want CodeView debug information on MSVC
	if cx.sess().target.target.options.is_like_msvc {
	llvm::LLVMRustAddModuleFlag(cx.llmod,
	"CodeView\0".as_ptr() as *const _,
	1)
	}

	// Prevent bitcode readers from deleting the debug info.
	let ptr = "Debug Info Version\0".as_ptr();
	llvm::LLVMRustAddModuleFlag(cx.llmod, ptr as *const _,
	llvm::LLVMRustDebugMetadataVersion());
	};
	}

	/// Creates the function-specific debug context.
	///
	/// Returns the FunctionDebugContext for the function which holds state needed
	/// for debug info creation. The function may also return another variant of the
	/// FunctionDebugContext enum which indicates why no debuginfo should be created
	/// for the function.
	pub fn create_function_debug_context<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
	instance: Instance<'tcx>,
	sig: ty::FnSig<'tcx>,
	llfn: ValueRef,
	mir: &mir::Mir) -> FunctionDebugContext {
	if cx.sess().opts.debuginfo == NoDebugInfo {
	return FunctionDebugContext::DebugInfoDisabled;
	}

	for attr in instance.def.attrs(cx.tcx).iter() {
	if attr.check_name("no_debug") {
	return FunctionDebugContext::FunctionWithoutDebugInfo;
	}
	}

	let containing_scope = get_containing_scope(cx, instance);
	let span = mir.span;

	// This can be the case for functions inlined from another crate
	if span == syntax_pos::DUMMY_SP {
	// FIXME(simulacrum): Probably can't happen; remove.
	return FunctionDebugContext::FunctionWithoutDebugInfo;
	}

	let def_id = instance.def_id();
	let loc = span_start(cx, span);
	let file_metadata = file_metadata(cx, &loc.file.name, def_id.krate);

	let function_type_metadata = unsafe {
	let fn_signature = get_function_signature(cx, sig);
	llvm::LLVMRustDIBuilderCreateSubroutineType(DIB(cx), file_metadata, fn_signature)
	};

	// Find the enclosing function, in case this is a closure.
	let def_key = cx.tcx.def_key(def_id);
	let mut name = def_key.disambiguated_data.data.to_string();

	let enclosing_fn_def_id = cx.tcx.closure_base_def_id(def_id);

	// Get_template_parameters() will append a `<...>` clause to the function
	// name if necessary.
	let generics = cx.tcx.generics_of(enclosing_fn_def_id);
	let substs = instance.substs.truncate_to(cx.tcx, generics);
	let template_parameters = get_template_parameters(cx,
	&generics,
	substs,
	file_metadata,
	&mut name);

	// Get the linkage_name, which is just the symbol name
	let linkage_name = mangled_name_of_instance(cx, instance);

	let scope_line = span_start(cx, span).line;

	let local_id = cx.tcx.hir.as_local_node_id(instance.def_id());
	let is_local_to_unit = local_id.map_or(false, \|id\| is_node_local_to_unit(cx, id));

	let function_name = CString::new(name).unwrap();
	let linkage_name = CString::new(linkage_name.to_string()).unwrap();

	let mut flags = DIFlags::FlagPrototyped;
	match *cx.sess().entry_fn.borrow() {
	Some((id, _)) => {
	if local_id == Some(id) {
	flags = flags \| DIFlags::FlagMainSubprogram;
	}
	}
	None => {}
	};

	let fn_metadata = unsafe {
	llvm::LLVMRustDIBuilderCreateFunction(
	DIB(cx),
	containing_scope,
	function_name.as_ptr(),
	linkage_name.as_ptr(),
	file_metadata,
	loc.line as c_uint,
	function_type_metadata,
	is_local_to_unit,
	true,
	scope_line as c_uint,
	flags,
	cx.sess().opts.optimize != config::OptLevel::No,
	llfn,
	template_parameters,
	ptr::null_mut())
	};

	// Initialize fn debug context (including scope map and namespace map)
	let fn_debug_context = FunctionDebugContextData {
	fn_metadata,
	source_locations_enabled: Cell::new(false),
	defining_crate: def_id.krate,
	};

	return FunctionDebugContext::RegularContext(fn_debug_context);

	fn get_function_signature<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
	sig: ty::FnSig<'tcx>) -> DIArray {
	if cx.sess().opts.debuginfo == LimitedDebugInfo {
	return create_DIArray(DIB(cx), &[]);
	}

	let mut signature = Vec::with_capacity(sig.inputs().len() + 1);

	// Return type -- llvm::DIBuilder wants this at index 0
	signature.push(match sig.output().sty {
	ty::TyTuple(ref tys, _) if tys.is_empty() => ptr::null_mut(),
	_ => type_metadata(cx, sig.output(), syntax_pos::DUMMY_SP)
	});

	let inputs = if sig.abi == Abi::RustCall {
	&sig.inputs()[..sig.inputs().len() - 1]
	} else {
	sig.inputs()
	};

	// Arguments types
	if cx.sess().target.target.options.is_like_msvc {
	// FIXME(#42800):
	// There is a bug in MSDIA that leads to a crash when it encounters
	// a fixed-size array of `u8` or something zero-sized in a
	// function-type (see #40477).
	// As a workaround, we replace those fixed-size arrays with a
	// pointer-type. So a function `fn foo(a: u8, b: [u8; 4])` would
	// appear as `fn foo(a: u8, b: *const u8)` in debuginfo,
	// and a function `fn bar(x: [(); 7])` as `fn bar(x: *const ())`.
	// This transformed type is wrong, but these function types are
	// already inaccurate due to ABI adjustments (see #42800).
	signature.extend(inputs.iter().map(\|&t\| {
	let t = match t.sty {
	ty::TyArray(ct, _)
	if (ct == cx.tcx.types.u8) \|\| cx.layout_of(ct).is_zst() => {
	cx.tcx.mk_imm_ptr(ct)
	}
	_ => t
	};
	type_metadata(cx, t, syntax_pos::DUMMY_SP)
	}));
	} else {
	signature.extend(inputs.iter().map(\|t\| {
	type_metadata(cx, t, syntax_pos::DUMMY_SP)
	}));
	}

	if sig.abi == Abi::RustCall && !sig.inputs().is_empty() {
	if let ty::TyTuple(args, _) = sig.inputs()[sig.inputs().len() - 1].sty {
	for &argument_type in args {
	signature.push(type_metadata(cx, argument_type, syntax_pos::DUMMY_SP));
	}
	}
	}

	return create_DIArray(DIB(cx), &signature[..]);
	}

	fn get_template_parameters<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
	generics: &ty::Generics,
	substs: &Substs<'tcx>,
	file_metadata: DIFile,
	name_to_append_suffix_to: &mut String)
	-> DIArray
	{
	if substs.types().next().is_none() {
	return create_DIArray(DIB(cx), &[]);
	}

	name_to_append_suffix_to.push('<');
	for (i, actual_type) in substs.types().enumerate() {
	if i != 0 {
	name_to_append_suffix_to.push_str(",");
	}

	let actual_type = cx.tcx.fully_normalize_associated_types_in(&actual_type);
	// Add actual type name to <...> clause of function name
	let actual_type_name = compute_debuginfo_type_name(cx,
	actual_type,
	true);
	name_to_append_suffix_to.push_str(&actual_type_name[..]);
	}
	name_to_append_suffix_to.push('>');

	// Again, only create type information if full debuginfo is enabled
	let template_params: Vec<_> = if cx.sess().opts.debuginfo == FullDebugInfo {
	let names = get_type_parameter_names(cx, generics);
	substs.types().zip(names).map(\|(ty, name)\| {
	let actual_type = cx.tcx.fully_normalize_associated_types_in(&ty);
	let actual_type_metadata = type_metadata(cx, actual_type, syntax_pos::DUMMY_SP);
	let name = CString::new(name.as_str().as_bytes()).unwrap();
	unsafe {
	llvm::LLVMRustDIBuilderCreateTemplateTypeParameter(
	DIB(cx),
	ptr::null_mut(),
	name.as_ptr(),
	actual_type_metadata,
	file_metadata,
	0,
	0)
	}
	}).collect()
	} else {
	vec![]
	};

	return create_DIArray(DIB(cx), &template_params[..]);
	}

	fn get_type_parameter_names(cx: &CodegenCx, generics: &ty::Generics) -> Vec<ast::Name> {
	let mut names = generics.parent.map_or(vec![], \|def_id\| {
	get_type_parameter_names(cx, cx.tcx.generics_of(def_id))
	});
	names.extend(generics.types.iter().map(\|param\| param.name));
	names
	}

	fn get_containing_scope<'cx, 'tcx>(cx: &CodegenCx<'cx, 'tcx>,
	instance: Instance<'tcx>)
	-> DIScope {
	// First, let's see if this is a method within an inherent impl. Because
	// if yes, we want to make the result subroutine DIE a child of the
	// subroutine's self-type.
	let self_type = cx.tcx.impl_of_method(instance.def_id()).and_then(\|impl_def_id\| {
	// If the method does not belong to a trait, proceed
	if cx.tcx.trait_id_of_impl(impl_def_id).is_none() {
	let impl_self_ty = cx.tcx.trans_impl_self_ty(impl_def_id, instance.substs);

	// Only "class" methods are generally understood by LLVM,
	// so avoid methods on other types (e.g. `<*mut T>::null`).
	match impl_self_ty.sty {
	ty::TyAdt(def, ..) if !def.is_box() => {
	Some(type_metadata(cx, impl_self_ty, syntax_pos::DUMMY_SP))
	}
	_ => None
	}
	} else {
	// For trait method impls we still use the "parallel namespace"
	// strategy
	None
	}
	});

	self_type.unwrap_or_else(\|\| {
	namespace::item_namespace(cx, DefId {
	krate: instance.def_id().krate,
	index: cx.tcx
	.def_key(instance.def_id())
	.parent
	.expect("get_containing_scope: missing parent?")
	})
	})
	}
	}

	pub fn declare_local<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
	dbg_context: &FunctionDebugContext,
	variable_name: ast::Name,
	variable_type: Ty<'tcx>,
	scope_metadata: DIScope,
	variable_access: VariableAccess,
	variable_kind: VariableKind,
	span: Span) {
	let cx = bx.cx;

	let file = span_start(cx, span).file;
	let file_metadata = file_metadata(cx,
	&file.name,
	dbg_context.get_ref(span).defining_crate);

	let loc = span_start(cx, span);
	let type_metadata = type_metadata(cx, variable_type, span);

	let (argument_index, dwarf_tag) = match variable_kind {
	ArgumentVariable(index) => (index as c_uint, DW_TAG_arg_variable),
	LocalVariable \|
	CapturedVariable => (0, DW_TAG_auto_variable)
	};
	let align = cx.align_of(variable_type);

	let name = CString::new(variable_name.as_str().as_bytes()).unwrap();
	match (variable_access, &[][..]) {
	(DirectVariable { alloca }, address_operations) \|
	(IndirectVariable {alloca, address_operations}, _) => {
	let metadata = unsafe {
	llvm::LLVMRustDIBuilderCreateVariable(
	DIB(cx),
	dwarf_tag,
	scope_metadata,
	name.as_ptr(),
	file_metadata,
	loc.line as c_uint,
	type_metadata,
	cx.sess().opts.optimize != config::OptLevel::No,
	DIFlags::FlagZero,
	argument_index,
	align.abi() as u32,
	)
	};
	source_loc::set_debug_location(bx,
	InternalDebugLocation::new(scope_metadata, loc.line, loc.col.to_usize()));
	unsafe {
	let debug_loc = llvm::LLVMGetCurrentDebugLocation(bx.llbuilder);
	let instr = llvm::LLVMRustDIBuilderInsertDeclareAtEnd(
	DIB(cx),
	alloca,
	metadata,
	address_operations.as_ptr(),
	address_operations.len() as c_uint,
	debug_loc,
	bx.llbb());

	llvm::LLVMSetInstDebugLocation(bx.llbuilder, instr);
	}
	}
	}

	match variable_kind {
	ArgumentVariable(_) \| CapturedVariable => {
	assert!(!dbg_context.get_ref(span).source_locations_enabled.get());
	source_loc::set_debug_location(bx, UnknownLocation);
	}
	_ => { /* nothing to do */ }
	}
	}