use crate::traits::*; use rustc_index::vec::IndexVec; use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags; use rustc_middle::mir; use rustc_middle::ty; use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf}; use rustc_session::config::DebugInfo; use rustc_span::symbol::{kw, Symbol}; use rustc_span::{BytePos, Span}; use rustc_target::abi::Abi; use rustc_target::abi::Size; use super::operand::{OperandRef, OperandValue}; use super::place::PlaceRef; use super::{FunctionCx, LocalRef}; pub struct FunctionDebugContext { pub scopes: IndexVec>, } #[derive(Copy, Clone)] pub enum VariableKind { ArgumentVariable(usize /*index*/), LocalVariable, } /// Like `mir::VarDebugInfo`, but within a `mir::Local`. #[derive(Copy, Clone)] pub struct PerLocalVarDebugInfo<'tcx, D> { pub name: Symbol, pub source_info: mir::SourceInfo, /// `DIVariable` returned by `create_dbg_var`. pub dbg_var: Option, /// `.place.projection` from `mir::VarDebugInfo`. pub projection: &'tcx ty::List>, } #[derive(Clone, Copy, Debug)] pub struct DebugScope { pub dbg_scope: S, /// Call site location, if this scope was inlined from another function. pub inlined_at: Option, // Start and end offsets of the file to which this DIScope belongs. // These are used to quickly determine whether some span refers to the same file. pub file_start_pos: BytePos, pub file_end_pos: BytePos, } impl<'tcx, S: Copy, L: Copy> DebugScope { /// DILocations inherit source file name from the parent DIScope. Due to macro expansions /// it may so happen that the current span belongs to a different file than the DIScope /// corresponding to span's containing source scope. If so, we need to create a DIScope /// "extension" into that file. pub fn adjust_dbg_scope_for_span>( &self, cx: &Cx, span: Span, ) -> S { let pos = span.lo(); if pos < self.file_start_pos || pos >= self.file_end_pos { let sm = cx.sess().source_map(); cx.extend_scope_to_file(self.dbg_scope, &sm.lookup_char_pos(pos).file) } else { self.dbg_scope } } } impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { pub fn set_debug_loc(&self, bx: &mut Bx, source_info: mir::SourceInfo) { bx.set_span(source_info.span); if let Some(dbg_loc) = self.dbg_loc(source_info) { bx.set_dbg_loc(dbg_loc); } } fn dbg_loc(&self, source_info: mir::SourceInfo) -> Option { let (dbg_scope, inlined_at, span) = self.adjusted_span_and_dbg_scope(source_info)?; Some(self.cx.dbg_loc(dbg_scope, inlined_at, span)) } fn adjusted_span_and_dbg_scope( &self, source_info: mir::SourceInfo, ) -> Option<(Bx::DIScope, Option, Span)> { let span = self.adjust_span_for_debugging(source_info.span); let scope = &self.debug_context.as_ref()?.scopes[source_info.scope]; Some((scope.adjust_dbg_scope_for_span(self.cx, span), scope.inlined_at, span)) } /// In order to have a good line stepping behavior in debugger, we overwrite debug /// locations of macro expansions with that of the outermost expansion site (when the macro is /// annotated with `#[collapse_debuginfo]` or when `-Zdebug-macros` is provided). fn adjust_span_for_debugging(&self, mut span: Span) -> Span { // Bail out if debug info emission is not enabled. if self.debug_context.is_none() { return span; } if self.cx.tcx().should_collapse_debuginfo(span) { // Walk up the macro expansion chain until we reach a non-expanded span. // We also stop at the function body level because no line stepping can occur // at the level above that. // Use span of the outermost expansion site, while keeping the original lexical scope. span = rustc_span::hygiene::walk_chain(span, self.mir.span.ctxt()); } span } fn spill_operand_to_stack( operand: &OperandRef<'tcx, Bx::Value>, name: Option, bx: &mut Bx, ) -> PlaceRef<'tcx, Bx::Value> { // "Spill" the value onto the stack, for debuginfo, // without forcing non-debuginfo uses of the local // to also load from the stack every single time. // FIXME(#68817) use `llvm.dbg.value` instead, // at least for the cases which LLVM handles correctly. let spill_slot = PlaceRef::alloca(bx, operand.layout); if let Some(name) = name { bx.set_var_name(spill_slot.llval, &(name + ".dbg.spill")); } operand.val.store(bx, spill_slot); spill_slot } /// Apply debuginfo and/or name, after creating the `alloca` for a local, /// or initializing the local with an operand (whichever applies). pub fn debug_introduce_local(&self, bx: &mut Bx, local: mir::Local) { let full_debug_info = bx.sess().opts.debuginfo == DebugInfo::Full; // FIXME(eddyb) maybe name the return place as `_0` or `return`? if local == mir::RETURN_PLACE && !self.mir.local_decls[mir::RETURN_PLACE].is_user_variable() { return; } let vars = match &self.per_local_var_debug_info { Some(per_local) => &per_local[local], None => return, }; let whole_local_var = vars.iter().find(|var| var.projection.is_empty()).copied(); let has_proj = || vars.iter().any(|var| !var.projection.is_empty()); let fallback_var = if self.mir.local_kind(local) == mir::LocalKind::Arg { let arg_index = local.index() - 1; // Add debuginfo even to unnamed arguments. // FIXME(eddyb) is this really needed? if arg_index == 0 && has_proj() { // Hide closure environments from debuginfo. // FIXME(eddyb) shouldn't `ArgumentVariable` indices // be offset to account for the hidden environment? None } else if whole_local_var.is_some() { // No need to make up anything, there is a `mir::VarDebugInfo` // covering the whole local. // FIXME(eddyb) take `whole_local_var.source_info.scope` into // account, just in case it doesn't use `ArgumentVariable` // (after #67586 gets fixed). None } else { let name = kw::Empty; let decl = &self.mir.local_decls[local]; let dbg_var = if full_debug_info { self.adjusted_span_and_dbg_scope(decl.source_info).map( |(dbg_scope, _, span)| { // FIXME(eddyb) is this `+ 1` needed at all? let kind = VariableKind::ArgumentVariable(arg_index + 1); let arg_ty = self.monomorphize(decl.ty); self.cx.create_dbg_var(name, arg_ty, dbg_scope, kind, span) }, ) } else { None }; Some(PerLocalVarDebugInfo { name, source_info: decl.source_info, dbg_var, projection: ty::List::empty(), }) } } else { None }; let local_ref = &self.locals[local]; let name = if bx.sess().fewer_names() { None } else { Some(match whole_local_var.or(fallback_var) { Some(var) if var.name != kw::Empty => var.name.to_string(), _ => format!("{:?}", local), }) }; if let Some(name) = &name { match local_ref { LocalRef::Place(place) | LocalRef::UnsizedPlace(place) => { bx.set_var_name(place.llval, name); } LocalRef::Operand(Some(operand)) => match operand.val { OperandValue::Ref(x, ..) | OperandValue::Immediate(x) => { bx.set_var_name(x, name); } OperandValue::Pair(a, b) => { // FIXME(eddyb) these are scalar components, // maybe extract the high-level fields? bx.set_var_name(a, &(name.clone() + ".0")); bx.set_var_name(b, &(name.clone() + ".1")); } }, LocalRef::Operand(None) => {} } } if !full_debug_info || vars.is_empty() && fallback_var.is_none() { return; } let base = match local_ref { LocalRef::Operand(None) => return, LocalRef::Operand(Some(operand)) => { // Don't spill operands onto the stack in naked functions. // See: https://github.com/rust-lang/rust/issues/42779 let attrs = bx.tcx().codegen_fn_attrs(self.instance.def_id()); if attrs.flags.contains(CodegenFnAttrFlags::NAKED) { return; } Self::spill_operand_to_stack(operand, name, bx) } LocalRef::Place(place) => *place, // FIXME(eddyb) add debuginfo for unsized places too. LocalRef::UnsizedPlace(_) => return, }; let vars = vars.iter().copied().chain(fallback_var); for var in vars { let Some(dbg_var) = var.dbg_var else { continue }; let Some(dbg_loc) = self.dbg_loc(var.source_info) else { continue }; let mut direct_offset = Size::ZERO; // FIXME(eddyb) use smallvec here. let mut indirect_offsets = vec![]; let mut place = base; for elem in &var.projection[..] { match *elem { mir::ProjectionElem::Deref => { indirect_offsets.push(Size::ZERO); place = bx.load_operand(place).deref(bx.cx()); } mir::ProjectionElem::Field(field, _) => { let i = field.index(); let offset = indirect_offsets.last_mut().unwrap_or(&mut direct_offset); *offset += place.layout.fields.offset(i); place = place.project_field(bx, i); } mir::ProjectionElem::Downcast(_, variant) => { place = place.project_downcast(bx, variant); } _ => span_bug!( var.source_info.span, "unsupported var debuginfo place `{:?}`", mir::Place { local, projection: var.projection }, ), } } // When targeting MSVC, create extra allocas for arguments instead of pointing multiple // dbg_var_addr() calls into the same alloca with offsets. MSVC uses CodeView records // not DWARF and LLVM doesn't support translating the resulting // [DW_OP_deref, DW_OP_plus_uconst, offset, DW_OP_deref] debug info to CodeView. // Creating extra allocas on the stack makes the resulting debug info simple enough // that LLVM can generate correct CodeView records and thus the values appear in the // debugger. (#83709) let should_create_individual_allocas = bx.cx().sess().target.is_like_msvc && self.mir.local_kind(local) == mir::LocalKind::Arg // LLVM can handle simple things but anything more complex than just a direct // offset or one indirect offset of 0 is too complex for it to generate CV records // correctly. && (direct_offset != Size::ZERO || !matches!(&indirect_offsets[..], [Size::ZERO] | [])); if should_create_individual_allocas { // Create a variable which will be a pointer to the actual value let ptr_ty = bx.tcx().mk_ty(ty::RawPtr(ty::TypeAndMut { mutbl: mir::Mutability::Mut, ty: place.layout.ty, })); let ptr_layout = bx.layout_of(ptr_ty); let alloca = PlaceRef::alloca(bx, ptr_layout); bx.set_var_name(alloca.llval, &(var.name.to_string() + ".dbg.spill")); // Write the pointer to the variable bx.store(place.llval, alloca.llval, alloca.align); // Point the debug info to `*alloca` for the current variable bx.dbg_var_addr(dbg_var, dbg_loc, alloca.llval, Size::ZERO, &[Size::ZERO]); } else { bx.dbg_var_addr(dbg_var, dbg_loc, base.llval, direct_offset, &indirect_offsets); } } } pub fn debug_introduce_locals(&self, bx: &mut Bx) { if bx.sess().opts.debuginfo == DebugInfo::Full || !bx.sess().fewer_names() { for local in self.locals.indices() { self.debug_introduce_local(bx, local); } } } /// Partition all `VarDebugInfo` in `self.mir`, by their base `Local`. pub fn compute_per_local_var_debug_info( &self, bx: &mut Bx, ) -> Option>>> { let full_debug_info = self.cx.sess().opts.debuginfo == DebugInfo::Full; let target_is_msvc = self.cx.sess().target.is_like_msvc; if !full_debug_info && self.cx.sess().fewer_names() { return None; } let mut per_local = IndexVec::from_elem(vec![], &self.mir.local_decls); for var in &self.mir.var_debug_info { let dbg_scope_and_span = if full_debug_info { self.adjusted_span_and_dbg_scope(var.source_info) } else { None }; let dbg_var = dbg_scope_and_span.map(|(dbg_scope, _, span)| { let (var_ty, var_kind) = match var.value { mir::VarDebugInfoContents::Place(place) => { let var_ty = self.monomorphized_place_ty(place.as_ref()); let var_kind = if self.mir.local_kind(place.local) == mir::LocalKind::Arg && place.projection.is_empty() && var.source_info.scope == mir::OUTERMOST_SOURCE_SCOPE { let arg_index = place.local.index() - 1; if target_is_msvc { // ScalarPair parameters are spilled to the stack so they need to // be marked as a `LocalVariable` for MSVC debuggers to visualize // their data correctly. (See #81894 & #88625) let var_ty_layout = self.cx.layout_of(var_ty); if let Abi::ScalarPair(_, _) = var_ty_layout.abi { VariableKind::LocalVariable } else { VariableKind::ArgumentVariable(arg_index + 1) } } else { // FIXME(eddyb) shouldn't `ArgumentVariable` indices be // offset in closures to account for the hidden environment? // Also, is this `+ 1` needed at all? VariableKind::ArgumentVariable(arg_index + 1) } } else { VariableKind::LocalVariable }; (var_ty, var_kind) } mir::VarDebugInfoContents::Const(c) => { let ty = self.monomorphize(c.ty()); (ty, VariableKind::LocalVariable) } }; self.cx.create_dbg_var(var.name, var_ty, dbg_scope, var_kind, span) }); match var.value { mir::VarDebugInfoContents::Place(place) => { per_local[place.local].push(PerLocalVarDebugInfo { name: var.name, source_info: var.source_info, dbg_var, projection: place.projection, }); } mir::VarDebugInfoContents::Const(c) => { if let Some(dbg_var) = dbg_var { let Some(dbg_loc) = self.dbg_loc(var.source_info) else { continue }; if let Ok(operand) = self.eval_mir_constant_to_operand(bx, &c) { let base = Self::spill_operand_to_stack( &operand, Some(var.name.to_string()), bx, ); bx.dbg_var_addr(dbg_var, dbg_loc, base.llval, Size::ZERO, &[]); } } } } } Some(per_local) } }