From a84909c1e78aef244385b46db080bf78ce548881 Mon Sep 17 00:00:00 2001 From: Camille GILLOT Date: Sat, 14 Jan 2023 22:23:49 +0000 Subject: [PATCH] Enforce VarDebugInfo::Place in MIR validation. --- .../rustc_codegen_ssa/src/mir/debuginfo.rs | 14 +++--- .../src/transform/validate.rs | 43 +++++++++++++++++-- compiler/rustc_middle/src/mir/mod.rs | 24 ++++++++--- 3 files changed, 65 insertions(+), 16 deletions(-) diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs index d15774696a52b..8549abd6e390c 100644 --- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs +++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs @@ -165,11 +165,15 @@ fn calculate_debuginfo_offset< mir::ProjectionElem::Downcast(_, variant) => { place = place.downcast(bx, variant); } - _ => span_bug!( - var.source_info.span, - "unsupported var debuginfo place `{:?}`", - mir::Place { local, projection: var.projection }, - ), + _ => { + // Sanity check for `can_use_in_debuginfo`. + debug_assert!(!elem.can_use_in_debuginfo()); + span_bug!( + var.source_info.span, + "unsupported var debuginfo place `{:?}`", + mir::Place { local, projection: var.projection }, + ) + } } } diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs index 2be385d551e8a..5d7c0faf8517a 100644 --- a/compiler/rustc_const_eval/src/transform/validate.rs +++ b/compiler/rustc_const_eval/src/transform/validate.rs @@ -5,13 +5,12 @@ use rustc_index::bit_set::BitSet; use rustc_index::vec::IndexVec; use rustc_infer::traits::Reveal; use rustc_middle::mir::interpret::Scalar; -use rustc_middle::mir::visit::NonUseContext::VarDebugInfo; -use rustc_middle::mir::visit::{PlaceContext, Visitor}; +use rustc_middle::mir::visit::{NonUseContext, PlaceContext, Visitor}; use rustc_middle::mir::{ traversal, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping, Local, Location, MirPass, MirPhase, NonDivergingIntrinsic, Operand, Place, PlaceElem, PlaceRef, ProjectionElem, RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind, Terminator, - TerminatorKind, UnOp, START_BLOCK, + TerminatorKind, UnOp, VarDebugInfo, VarDebugInfoContents, START_BLOCK, }; use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt}; use rustc_mir_dataflow::impls::MaybeStorageLive; @@ -419,13 +418,49 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> { self.super_projection_elem(local, proj_base, elem, context, location); } + fn visit_var_debug_info(&mut self, debuginfo: &VarDebugInfo<'tcx>) { + let check_place = |place: Place<'_>| { + if place.projection.iter().any(|p| !p.can_use_in_debuginfo()) { + self.fail( + START_BLOCK.start_location(), + format!("illegal place {:?} in debuginfo for {:?}", place, debuginfo.name), + ); + } + }; + match debuginfo.value { + VarDebugInfoContents::Const(_) => {} + VarDebugInfoContents::Place(place) => check_place(place), + VarDebugInfoContents::Composite { ty, ref fragments } => { + for f in fragments { + check_place(f.contents); + if ty.is_union() || ty.is_enum() { + self.fail( + START_BLOCK.start_location(), + format!("invalid type {:?} for composite debuginfo", ty), + ); + } + if f.projection.iter().any(|p| !matches!(p, PlaceElem::Field(..))) { + self.fail( + START_BLOCK.start_location(), + format!( + "illegal projection {:?} in debuginfo for {:?}", + f.projection, debuginfo.name + ), + ); + } + } + } + } + self.super_var_debug_info(debuginfo); + } + fn visit_place(&mut self, place: &Place<'tcx>, cntxt: PlaceContext, location: Location) { // Set off any `bug!`s in the type computation code let _ = place.ty(&self.body.local_decls, self.tcx); if self.mir_phase >= MirPhase::Runtime(RuntimePhase::Initial) && place.projection.len() > 1 - && cntxt != PlaceContext::NonUse(VarDebugInfo) + && cntxt != PlaceContext::NonUse(NonUseContext::VarDebugInfo) && place.projection[1..].contains(&ProjectionElem::Deref) { self.fail(location, format!("{:?}, has deref at the wrong place", place)); diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs index 9c575f6eb9fd0..9604fb5743d37 100644 --- a/compiler/rustc_middle/src/mir/mod.rs +++ b/compiler/rustc_middle/src/mir/mod.rs @@ -1029,8 +1029,7 @@ impl<'tcx> LocalDecl<'tcx> { #[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)] pub enum VarDebugInfoContents<'tcx> { - /// NOTE(eddyb) There's an unenforced invariant that this `Place` is - /// based on a `Local`, not a `Static`, and contains no indexing. + /// This `Place` only contains projection which satisfy `can_use_in_debuginfo`. Place(Place<'tcx>), Const(Constant<'tcx>), /// The user variable's data is split across several fragments, @@ -1040,6 +1039,7 @@ pub enum VarDebugInfoContents<'tcx> { /// the underlying debuginfo feature this relies on. Composite { /// Type of the original user variable. + /// This cannot contain a union or an enum. ty: Ty<'tcx>, /// All the parts of the original user variable, which ended /// up in disjoint places, due to optimizations. @@ -1068,17 +1068,16 @@ pub struct VarDebugInfoFragment<'tcx> { /// Where in the composite user variable this fragment is, /// represented as a "projection" into the composite variable. /// At lower levels, this corresponds to a byte/bit range. - // NOTE(eddyb) there's an unenforced invariant that this contains - // only `Field`s, and not into `enum` variants or `union`s. - // FIXME(eddyb) support this for `enum`s by either using DWARF's + /// + /// This can only contain `PlaceElem::Field`. + // FIXME support this for `enum`s by either using DWARF's // more advanced control-flow features (unsupported by LLVM?) // to match on the discriminant, or by using custom type debuginfo // with non-overlapping variants for the composite variable. pub projection: Vec>, /// Where the data for this fragment can be found. - // NOTE(eddyb) There's an unenforced invariant that this `Place` is - // contains no indexing (with a non-constant index). + /// This `Place` only contains projection which satisfy `can_use_in_debuginfo`. pub contents: Place<'tcx>, } @@ -1515,6 +1514,17 @@ impl ProjectionElem { pub fn is_field_to(&self, f: Field) -> bool { matches!(*self, Self::Field(x, _) if x == f) } + + /// Returns `true` if this is accepted inside `VarDebugInfoContents::Place`. + pub fn can_use_in_debuginfo(&self) -> bool { + match self { + Self::Deref | Self::Downcast(_, _) | Self::Field(_, _) => true, + Self::ConstantIndex { .. } + | Self::Index(_) + | Self::OpaqueCast(_) + | Self::Subslice { .. } => false, + } + } } /// Alias for projections as they appear in `UserTypeProjection`, where we