compiler/rustc_codegen_llvm/src/debuginfo/mod.rs

   1 #![doc = include_str!("doc.md")]
   2
   3 use rustc_codegen_ssa::mir::debuginfo::VariableKind::*;
   4
   5 use self::metadata::{file_metadata, type_metadata, TypeMap};
   6 use self::metadata::{UNKNOWN_COLUMN_NUMBER, UNKNOWN_LINE_NUMBER};
   7 use self::namespace::mangled_name_of_instance;
   8 use self::utils::{create_DIArray, is_node_local_to_unit, DIB};
   9
  10 use crate::abi::FnAbi;
  11 use crate::builder::Builder;
  12 use crate::common::CodegenCx;
  13 use crate::llvm;
  14 use crate::llvm::debuginfo::{
  15     DIArray, DIBuilder, DIFile, DIFlags, DILexicalBlock, DILocation, DISPFlags, DIScope, DIType,
  16     DIVariable,
  17 };
  18 use crate::value::Value;
  19
  20 use rustc_codegen_ssa::debuginfo::type_names;
  21 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext, VariableKind};
  22 use rustc_codegen_ssa::traits::*;
  23 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  24 use rustc_data_structures::sync::Lrc;
  25 use rustc_hir::def_id::{DefId, DefIdMap};
  26 use rustc_index::vec::IndexVec;
  27 use rustc_middle::mir;
  28 use rustc_middle::ty::layout::HasTyCtxt;
  29 use rustc_middle::ty::subst::{GenericArgKind, SubstsRef};
  30 use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TypeFoldable};
  31 use rustc_session::config::{self, DebugInfo};
  32 use rustc_span::symbol::Symbol;
  33 use rustc_span::{self, BytePos, Pos, SourceFile, SourceFileAndLine, Span};
  34 use rustc_target::abi::{LayoutOf, Primitive, Size};
  35
  36 use libc::c_uint;
  37 use smallvec::SmallVec;
  38 use std::cell::RefCell;
  39 use std::iter;
  40 use tracing::debug;
  41
  42 mod create_scope_map;
  43 pub mod gdb;
  44 pub mod metadata;
  45 mod namespace;
  46 mod utils;
  47
  48 pub use self::create_scope_map::compute_mir_scopes;
  49 pub use self::metadata::create_global_var_metadata;
  50 pub use self::metadata::extend_scope_to_file;
  51
  52 #[allow(non_upper_case_globals)]
  53 const DW_TAG_auto_variable: c_uint = 0x100;
  54 #[allow(non_upper_case_globals)]
  55 const DW_TAG_arg_variable: c_uint = 0x101;
  56
  57 /// A context object for maintaining all state needed by the debuginfo module.
  58 pub struct CrateDebugContext<'a, 'tcx> {
  59     llcontext: &'a llvm::Context,
  60     llmod: &'a llvm::Module,
  61     builder: &'a mut DIBuilder<'a>,
  62     created_files: RefCell<FxHashMap<(Option<String>, Option<String>), &'a DIFile>>,
  63     created_enum_disr_types: RefCell<FxHashMap<(DefId, Primitive), &'a DIType>>,
  64
  65     type_map: RefCell<TypeMap<'a, 'tcx>>,
  66     namespace_map: RefCell<DefIdMap<&'a DIScope>>,
  67
  68     // This collection is used to assert that composite types (structs, enums,
  69     // ...) have their members only set once:
  70     composite_types_completed: RefCell<FxHashSet<&'a DIType>>,
  71 }
  72
  73 impl Drop for CrateDebugContext<'a, 'tcx> {
  74     fn drop(&mut self) {
  75         unsafe {
  76             llvm::LLVMRustDIBuilderDispose(&mut *(self.builder as *mut _));
  77         }
  78     }
  79 }
  80
  81 impl<'a, 'tcx> CrateDebugContext<'a, 'tcx> {
  82     pub fn new(llmod: &'a llvm::Module) -> Self {
  83         debug!("CrateDebugContext::new");
  84         let builder = unsafe { llvm::LLVMRustDIBuilderCreate(llmod) };
  85         // DIBuilder inherits context from the module, so we'd better use the same one
  86         let llcontext = unsafe { llvm::LLVMGetModuleContext(llmod) };
  87         CrateDebugContext {
  88             llcontext,
  89             llmod,
  90             builder,
  91             created_files: Default::default(),
  92             created_enum_disr_types: Default::default(),
  93             type_map: Default::default(),
  94             namespace_map: RefCell::new(Default::default()),
  95             composite_types_completed: Default::default(),
  96         }
  97     }
  98 }
  99
 100 /// Creates any deferred debug metadata nodes
 101 pub fn finalize(cx: &CodegenCx<'_, '_>) {
 102     if cx.dbg_cx.is_none() {
 103         return;
 104     }
 105
 106     debug!("finalize");
 107
 108     if gdb::needs_gdb_debug_scripts_section(cx) {
 109         // Add a .debug_gdb_scripts section to this compile-unit. This will
 110         // cause GDB to try and load the gdb_load_rust_pretty_printers.py file,
 111         // which activates the Rust pretty printers for binary this section is
 112         // contained in.
 113         gdb::get_or_insert_gdb_debug_scripts_section_global(cx);
 114     }
 115
 116     unsafe {
 117         llvm::LLVMRustDIBuilderFinalize(DIB(cx));
 118         // Debuginfo generation in LLVM by default uses a higher
 119         // version of dwarf than macOS currently understands. We can
 120         // instruct LLVM to emit an older version of dwarf, however,
 121         // for macOS to understand. For more info see #11352
 122         // This can be overridden using --llvm-opts -dwarf-version,N.
 123         // Android has the same issue (#22398)
 124         if let Some(version) = cx.sess().target.dwarf_version {
 125             llvm::LLVMRustAddModuleFlag(cx.llmod, "Dwarf Version\0".as_ptr().cast(), version)
 126         }
 127
 128         // Indicate that we want CodeView debug information on MSVC
 129         if cx.sess().target.is_like_msvc {
 130             llvm::LLVMRustAddModuleFlag(cx.llmod, "CodeView\0".as_ptr().cast(), 1)
 131         }
 132
 133         // Prevent bitcode readers from deleting the debug info.
 134         let ptr = "Debug Info Version\0".as_ptr();
 135         llvm::LLVMRustAddModuleFlag(cx.llmod, ptr.cast(), llvm::LLVMRustDebugMetadataVersion());
 136     };
 137 }
 138
 139 impl DebugInfoBuilderMethods for Builder<'a, 'll, 'tcx> {
 140     // FIXME(eddyb) find a common convention for all of the debuginfo-related
 141     // names (choose between `dbg`, `debug`, `debuginfo`, `debug_info` etc.).
 142     fn dbg_var_addr(
 143         &mut self,
 144         dbg_var: &'ll DIVariable,
 145         dbg_loc: &'ll DILocation,
 146         variable_alloca: Self::Value,
 147         direct_offset: Size,
 148         indirect_offsets: &[Size],
 149     ) {
 150         // Convert the direct and indirect offsets to address ops.
 151         // FIXME(eddyb) use `const`s instead of getting the values via FFI,
 152         // the values should match the ones in the DWARF standard anyway.
 153         let op_deref = || unsafe { llvm::LLVMRustDIBuilderCreateOpDeref() };
 154         let op_plus_uconst = || unsafe { llvm::LLVMRustDIBuilderCreateOpPlusUconst() };
 155         let mut addr_ops = SmallVec::<[_; 8]>::new();
 156
 157         if direct_offset.bytes() > 0 {
 158             addr_ops.push(op_plus_uconst());
 159             addr_ops.push(direct_offset.bytes() as i64);
 160         }
 161         for &offset in indirect_offsets {
 162             addr_ops.push(op_deref());
 163             if offset.bytes() > 0 {
 164                 addr_ops.push(op_plus_uconst());
 165                 addr_ops.push(offset.bytes() as i64);
 166             }
 167         }
 168
 169         unsafe {
 170             // FIXME(eddyb) replace `llvm.dbg.declare` with `llvm.dbg.addr`.
 171             llvm::LLVMRustDIBuilderInsertDeclareAtEnd(
 172                 DIB(self.cx()),
 173                 variable_alloca,
 174                 dbg_var,
 175                 addr_ops.as_ptr(),
 176                 addr_ops.len() as c_uint,
 177                 dbg_loc,
 178                 self.llbb(),
 179             );
 180         }
 181     }
 182
 183     fn set_dbg_loc(&mut self, dbg_loc: &'ll DILocation) {
 184         unsafe {
 185             let dbg_loc_as_llval = llvm::LLVMRustMetadataAsValue(self.cx().llcx, dbg_loc);
 186             llvm::LLVMSetCurrentDebugLocation(self.llbuilder, dbg_loc_as_llval);
 187         }
 188     }
 189
 190     fn insert_reference_to_gdb_debug_scripts_section_global(&mut self) {
 191         gdb::insert_reference_to_gdb_debug_scripts_section_global(self)
 192     }
 193
 194     fn set_var_name(&mut self, value: &'ll Value, name: &str) {
 195         // Avoid wasting time if LLVM value names aren't even enabled.
 196         if self.sess().fewer_names() {
 197             return;
 198         }
 199
 200         // Only function parameters and instructions are local to a function,
 201         // don't change the name of anything else (e.g. globals).
 202         let param_or_inst = unsafe {
 203             llvm::LLVMIsAArgument(value).is_some() || llvm::LLVMIsAInstruction(value).is_some()
 204         };
 205         if !param_or_inst {
 206             return;
 207         }
 208
 209         // Avoid replacing the name if it already exists.
 210         // While we could combine the names somehow, it'd
 211         // get noisy quick, and the usefulness is dubious.
 212         if llvm::get_value_name(value).is_empty() {
 213             llvm::set_value_name(value, name.as_bytes());
 214         }
 215     }
 216 }
 217
 218 /// A source code location used to generate debug information.
 219 // FIXME(eddyb) rename this to better indicate it's a duplicate of
 220 // `rustc_span::Loc` rather than `DILocation`, perhaps by making
 221 // `lookup_char_pos` return the right information instead.
 222 pub struct DebugLoc {
 223     /// Information about the original source file.
 224     pub file: Lrc<SourceFile>,
 225     /// The (1-based) line number.
 226     pub line: u32,
 227     /// The (1-based) column number.
 228     pub col: u32,
 229 }
 230
 231 impl CodegenCx<'ll, '_> {
 232     /// Looks up debug source information about a `BytePos`.
 233     // FIXME(eddyb) rename this to better indicate it's a duplicate of
 234     // `lookup_char_pos` rather than `dbg_loc`, perhaps by making
 235     // `lookup_char_pos` return the right information instead.
 236     pub fn lookup_debug_loc(&self, pos: BytePos) -> DebugLoc {
 237         let (file, line, col) = match self.sess().source_map().lookup_line(pos) {
 238             Ok(SourceFileAndLine { sf: file, line }) => {
 239                 let line_pos = file.line_begin_pos(pos);
 240
 241                 // Use 1-based indexing.
 242                 let line = (line + 1) as u32;
 243                 let col = (pos - line_pos).to_u32() + 1;
 244
 245                 (file, line, col)
 246             }
 247             Err(file) => (file, UNKNOWN_LINE_NUMBER, UNKNOWN_COLUMN_NUMBER),
 248         };
 249
 250         // For MSVC, omit the column number.
 251         // Otherwise, emit it. This mimics clang behaviour.
 252         // See discussion in https://github.com/rust-lang/rust/issues/42921
 253         if self.sess().target.is_like_msvc {
 254             DebugLoc { file, line, col: UNKNOWN_COLUMN_NUMBER }
 255         } else {
 256             DebugLoc { file, line, col }
 257         }
 258     }
 259 }
 260
 261 impl DebugInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> {
 262     fn create_function_debug_context(
 263         &self,
 264         instance: Instance<'tcx>,
 265         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
 266         llfn: &'ll Value,
 267         mir: &mir::Body<'tcx>,
 268     ) -> Option<FunctionDebugContext<&'ll DIScope, &'ll DILocation>> {
 269         if self.sess().opts.debuginfo == DebugInfo::None {
 270             return None;
 271         }
 272
 273         // Initialize fn debug context (including scopes).
 274         // FIXME(eddyb) figure out a way to not need `Option` for `dbg_scope`.
 275         let empty_scope = DebugScope {
 276             dbg_scope: None,
 277             inlined_at: None,
 278             file_start_pos: BytePos(0),
 279             file_end_pos: BytePos(0),
 280         };
 281         let mut fn_debug_context =
 282             FunctionDebugContext { scopes: IndexVec::from_elem(empty_scope, &mir.source_scopes) };
 283
 284         // Fill in all the scopes, with the information from the MIR body.
 285         compute_mir_scopes(
 286             self,
 287             instance,
 288             mir,
 289             self.dbg_scope_fn(instance, fn_abi, Some(llfn)),
 290             &mut fn_debug_context,
 291         );
 292
 293         Some(fn_debug_context)
 294     }
 295
 296     fn dbg_scope_fn(
 297         &self,
 298         instance: Instance<'tcx>,
 299         fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
 300         maybe_definition_llfn: Option<&'ll Value>,
 301     ) -> &'ll DIScope {
 302         let def_id = instance.def_id();
 303         let containing_scope = get_containing_scope(self, instance);
 304         let span = self.tcx.def_span(def_id);
 305         let loc = self.lookup_debug_loc(span.lo());
 306         let file_metadata = file_metadata(self, &loc.file);
 307
 308         let function_type_metadata = unsafe {
 309             let fn_signature = get_function_signature(self, fn_abi);
 310             llvm::LLVMRustDIBuilderCreateSubroutineType(DIB(self), fn_signature)
 311         };
 312
 313         let mut name = String::new();
 314         type_names::push_item_name(self.tcx(), def_id, false, &mut name);
 315
 316         // Find the enclosing function, in case this is a closure.
 317         let enclosing_fn_def_id = self.tcx().closure_base_def_id(def_id);
 318
 319         // Get_template_parameters() will append a `<...>` clause to the function
 320         // name if necessary.
 321         let generics = self.tcx().generics_of(enclosing_fn_def_id);
 322         let substs = instance.substs.truncate_to(self.tcx(), generics);
 323         let template_parameters = get_template_parameters(self, &generics, substs, &mut name);
 324
 325         let linkage_name = &mangled_name_of_instance(self, instance).name;
 326         // Omit the linkage_name if it is the same as subprogram name.
 327         let linkage_name = if &name == linkage_name { "" } else { linkage_name };
 328
 329         // FIXME(eddyb) does this need to be separate from `loc.line` for some reason?
 330         let scope_line = loc.line;
 331
 332         let mut flags = DIFlags::FlagPrototyped;
 333
 334         if fn_abi.ret.layout.abi.is_uninhabited() {
 335             flags |= DIFlags::FlagNoReturn;
 336         }
 337
 338         let mut spflags = DISPFlags::SPFlagDefinition;
 339         if is_node_local_to_unit(self, def_id) {
 340             spflags |= DISPFlags::SPFlagLocalToUnit;
 341         }
 342         if self.sess().opts.optimize != config::OptLevel::No {
 343             spflags |= DISPFlags::SPFlagOptimized;
 344         }
 345         if let Some((id, _)) = self.tcx.entry_fn(()) {
 346             if id == def_id {
 347                 spflags |= DISPFlags::SPFlagMainSubprogram;
 348             }
 349         }
 350
 351         unsafe {
 352             return llvm::LLVMRustDIBuilderCreateFunction(
 353                 DIB(self),
 354                 containing_scope,
 355                 name.as_ptr().cast(),
 356                 name.len(),
 357                 linkage_name.as_ptr().cast(),
 358                 linkage_name.len(),
 359                 file_metadata,
 360                 loc.line,
 361                 function_type_metadata,
 362                 scope_line,
 363                 flags,
 364                 spflags,
 365                 maybe_definition_llfn,
 366                 template_parameters,
 367                 None,
 368             );
 369         }
 370
 371         fn get_function_signature<'ll, 'tcx>(
 372             cx: &CodegenCx<'ll, 'tcx>,
 373             fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
 374         ) -> &'ll DIArray {
 375             if cx.sess().opts.debuginfo == DebugInfo::Limited {
 376                 return create_DIArray(DIB(cx), &[]);
 377             }
 378
 379             let mut signature = Vec::with_capacity(fn_abi.args.len() + 1);
 380
 381             // Return type -- llvm::DIBuilder wants this at index 0
 382             signature.push(if fn_abi.ret.is_ignore() {
 383                 None
 384             } else {
 385                 Some(type_metadata(cx, fn_abi.ret.layout.ty, rustc_span::DUMMY_SP))
 386             });
 387
 388             // Arguments types
 389             if cx.sess().target.is_like_msvc {
 390                 // FIXME(#42800):
 391                 // There is a bug in MSDIA that leads to a crash when it encounters
 392                 // a fixed-size array of `u8` or something zero-sized in a
 393                 // function-type (see #40477).
 394                 // As a workaround, we replace those fixed-size arrays with a
 395                 // pointer-type. So a function `fn foo(a: u8, b: [u8; 4])` would
 396                 // appear as `fn foo(a: u8, b: *const u8)` in debuginfo,
 397                 // and a function `fn bar(x: [(); 7])` as `fn bar(x: *const ())`.
 398                 // This transformed type is wrong, but these function types are
 399                 // already inaccurate due to ABI adjustments (see #42800).
 400                 signature.extend(fn_abi.args.iter().map(|arg| {
 401                     let t = arg.layout.ty;
 402                     let t = match t.kind() {
 403                         ty::Array(ct, _)
 404                             if (*ct == cx.tcx.types.u8) || cx.layout_of(ct).is_zst() =>
 405                         {
 406                             cx.tcx.mk_imm_ptr(ct)
 407                         }
 408                         _ => t,
 409                     };
 410                     Some(type_metadata(cx, t, rustc_span::DUMMY_SP))
 411                 }));
 412             } else {
 413                 signature.extend(
 414                     fn_abi
 415                         .args
 416                         .iter()
 417                         .map(|arg| Some(type_metadata(cx, arg.layout.ty, rustc_span::DUMMY_SP))),
 418                 );
 419             }
 420
 421             create_DIArray(DIB(cx), &signature[..])
 422         }
 423
 424         fn get_template_parameters<'ll, 'tcx>(
 425             cx: &CodegenCx<'ll, 'tcx>,
 426             generics: &ty::Generics,
 427             substs: SubstsRef<'tcx>,
 428             name_to_append_suffix_to: &mut String,
 429         ) -> &'ll DIArray {
 430             type_names::push_generic_params(
 431                 cx.tcx,
 432                 cx.tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), substs),
 433                 name_to_append_suffix_to,
 434             );
 435
 436             if substs.types().next().is_none() {
 437                 return create_DIArray(DIB(cx), &[]);
 438             }
 439
 440             // Again, only create type information if full debuginfo is enabled
 441             let template_params: Vec<_> = if cx.sess().opts.debuginfo == DebugInfo::Full {
 442                 let names = get_parameter_names(cx, generics);
 443                 iter::zip(substs, names)
 444                     .filter_map(|(kind, name)| {
 445                         if let GenericArgKind::Type(ty) = kind.unpack() {
 446                             let actual_type =
 447                                 cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), ty);
 448                             let actual_type_metadata =
 449                                 type_metadata(cx, actual_type, rustc_span::DUMMY_SP);
 450                             let name = name.as_str();
 451                             Some(unsafe {
 452                                 Some(llvm::LLVMRustDIBuilderCreateTemplateTypeParameter(
 453                                     DIB(cx),
 454                                     None,
 455                                     name.as_ptr().cast(),
 456                                     name.len(),
 457                                     actual_type_metadata,
 458                                 ))
 459                             })
 460                         } else {
 461                             None
 462                         }
 463                     })
 464                     .collect()
 465             } else {
 466                 vec![]
 467             };
 468
 469             create_DIArray(DIB(cx), &template_params[..])
 470         }
 471
 472         fn get_parameter_names(cx: &CodegenCx<'_, '_>, generics: &ty::Generics) -> Vec<Symbol> {
 473             let mut names = generics.parent.map_or_else(Vec::new, |def_id| {
 474                 get_parameter_names(cx, cx.tcx.generics_of(def_id))
 475             });
 476             names.extend(generics.params.iter().map(|param| param.name));
 477             names
 478         }
 479
 480         fn get_containing_scope<'ll, 'tcx>(
 481             cx: &CodegenCx<'ll, 'tcx>,
 482             instance: Instance<'tcx>,
 483         ) -> &'ll DIScope {
 484             // First, let's see if this is a method within an inherent impl. Because
 485             // if yes, we want to make the result subroutine DIE a child of the
 486             // subroutine's self-type.
 487             let self_type = cx.tcx.impl_of_method(instance.def_id()).and_then(|impl_def_id| {
 488                 // If the method does *not* belong to a trait, proceed
 489                 if cx.tcx.trait_id_of_impl(impl_def_id).is_none() {
 490                     let impl_self_ty = cx.tcx.subst_and_normalize_erasing_regions(
 491                         instance.substs,
 492                         ty::ParamEnv::reveal_all(),
 493                         cx.tcx.type_of(impl_def_id),
 494                     );
 495
 496                     // Only "class" methods are generally understood by LLVM,
 497                     // so avoid methods on other types (e.g., `<*mut T>::null`).
 498                     match impl_self_ty.kind() {
 499                         ty::Adt(def, ..) if !def.is_box() => {
 500                             // Again, only create type information if full debuginfo is enabled
 501                             if cx.sess().opts.debuginfo == DebugInfo::Full
 502                                 && !impl_self_ty.needs_subst()
 503                             {
 504                                 Some(type_metadata(cx, impl_self_ty, rustc_span::DUMMY_SP))
 505                             } else {
 506                                 Some(namespace::item_namespace(cx, def.did))
 507                             }
 508                         }
 509                         _ => None,
 510                     }
 511                 } else {
 512                     // For trait method impls we still use the "parallel namespace"
 513                     // strategy
 514                     None
 515                 }
 516             });
 517
 518             self_type.unwrap_or_else(|| {
 519                 namespace::item_namespace(
 520                     cx,
 521                     DefId {
 522                         krate: instance.def_id().krate,
 523                         index: cx
 524                             .tcx
 525                             .def_key(instance.def_id())
 526                             .parent
 527                             .expect("get_containing_scope: missing parent?"),
 528                     },
 529                 )
 530             })
 531         }
 532     }
 533
 534     fn dbg_loc(
 535         &self,
 536         scope: &'ll DIScope,
 537         inlined_at: Option<&'ll DILocation>,
 538         span: Span,
 539     ) -> &'ll DILocation {
 540         let DebugLoc { line, col, .. } = self.lookup_debug_loc(span.lo());
 541
 542         unsafe { llvm::LLVMRustDIBuilderCreateDebugLocation(line, col, scope, inlined_at) }
 543     }
 544
 545     fn create_vtable_metadata(&self, ty: Ty<'tcx>, vtable: Self::Value) {
 546         metadata::create_vtable_metadata(self, ty, vtable)
 547     }
 548
 549     fn extend_scope_to_file(
 550         &self,
 551         scope_metadata: &'ll DIScope,
 552         file: &rustc_span::SourceFile,
 553     ) -> &'ll DILexicalBlock {
 554         metadata::extend_scope_to_file(&self, scope_metadata, file)
 555     }
 556
 557     fn debuginfo_finalize(&self) {
 558         finalize(self)
 559     }
 560
 561     // FIXME(eddyb) find a common convention for all of the debuginfo-related
 562     // names (choose between `dbg`, `debug`, `debuginfo`, `debug_info` etc.).
 563     fn create_dbg_var(
 564         &self,
 565         variable_name: Symbol,
 566         variable_type: Ty<'tcx>,
 567         scope_metadata: &'ll DIScope,
 568         variable_kind: VariableKind,
 569         span: Span,
 570     ) -> &'ll DIVariable {
 571         let loc = self.lookup_debug_loc(span.lo());
 572         let file_metadata = file_metadata(self, &loc.file);
 573
 574         let type_metadata = type_metadata(self, variable_type, span);
 575
 576         let (argument_index, dwarf_tag) = match variable_kind {
 577             ArgumentVariable(index) => (index as c_uint, DW_TAG_arg_variable),
 578             LocalVariable => (0, DW_TAG_auto_variable),
 579         };
 580         let align = self.align_of(variable_type);
 581
 582         let name = variable_name.as_str();
 583         unsafe {
 584             llvm::LLVMRustDIBuilderCreateVariable(
 585                 DIB(self),
 586                 dwarf_tag,
 587                 scope_metadata,
 588                 name.as_ptr().cast(),
 589                 name.len(),
 590                 file_metadata,
 591                 loc.line,
 592                 type_metadata,
 593                 true,
 594                 DIFlags::FlagZero,
 595                 argument_index,
 596                 align.bytes() as u32,
 597             )
 598         }
 599     }
 600 }