Auto merge of rust-lang#118015 - celinval:smir-place-ty, r=compiler-errors

Add place.ty() and Ty build from a kind to smir

Add a method to retrieve the type of a place and a few utility functions needed to build the projection type. I decided to return a result to avoid panicking if the user passes invalid inputs, such as wrong list of locals.

r? `@spastorino`

Author: bors

compiler/rustc_smir/src/rustc_internal/internal.rs

@@ -9,8 +9,8 @@ use rustc_middle::ty::{self as rustc_ty, Ty as InternalTy};
 use rustc_span::Symbol;
 use stable_mir::mir::mono::{Instance, MonoItem, StaticDef};
 use stable_mir::ty::{
-    Binder, BoundRegionKind, BoundTyKind, BoundVariableKind, ClosureKind, Const, GenericArgKind,
-    GenericArgs, Region, TraitRef, Ty,
+    AdtDef, Binder, BoundRegionKind, BoundTyKind, BoundVariableKind, ClosureKind, Const, FloatTy,
+    GenericArgKind, GenericArgs, IntTy, Region, RigidTy, TraitRef, Ty, UintTy,
 };
 use stable_mir::{AllocId, CrateItem, DefId};
 
@@ -63,6 +63,82 @@ impl<'tcx> RustcInternal<'tcx> for Ty {
     }
 }
 
+impl<'tcx> RustcInternal<'tcx> for RigidTy {
+    type T = rustc_ty::TyKind<'tcx>;
+
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            RigidTy::Bool => rustc_ty::TyKind::Bool,
+            RigidTy::Char => rustc_ty::TyKind::Char,
+            RigidTy::Int(int_ty) => rustc_ty::TyKind::Int(int_ty.internal(tables)),
+            RigidTy::Uint(uint_ty) => rustc_ty::TyKind::Uint(uint_ty.internal(tables)),
+            RigidTy::Float(float_ty) => rustc_ty::TyKind::Float(float_ty.internal(tables)),
+            RigidTy::Never => rustc_ty::TyKind::Never,
+            RigidTy::Array(ty, cnst) => {
+                rustc_ty::TyKind::Array(ty.internal(tables), ty_const(cnst, tables))
+            }
+            RigidTy::Adt(def, args) => {
+                rustc_ty::TyKind::Adt(def.internal(tables), args.internal(tables))
+            }
+            RigidTy::Str => rustc_ty::TyKind::Str,
+            RigidTy::Slice(ty) => rustc_ty::TyKind::Slice(ty.internal(tables)),
+            RigidTy::RawPtr(..)
+            | RigidTy::Ref(..)
+            | RigidTy::Foreign(_)
+            | RigidTy::FnDef(_, _)
+            | RigidTy::FnPtr(_)
+            | RigidTy::Closure(..)
+            | RigidTy::Coroutine(..)
+            | RigidTy::CoroutineWitness(..)
+            | RigidTy::Dynamic(..)
+            | RigidTy::Tuple(..) => {
+                todo!()
+            }
+        }
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for IntTy {
+    type T = rustc_ty::IntTy;
+
+    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            IntTy::Isize => rustc_ty::IntTy::Isize,
+            IntTy::I8 => rustc_ty::IntTy::I8,
+            IntTy::I16 => rustc_ty::IntTy::I16,
+            IntTy::I32 => rustc_ty::IntTy::I32,
+            IntTy::I64 => rustc_ty::IntTy::I64,
+            IntTy::I128 => rustc_ty::IntTy::I128,
+        }
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for UintTy {
+    type T = rustc_ty::UintTy;
+
+    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            UintTy::Usize => rustc_ty::UintTy::Usize,
+            UintTy::U8 => rustc_ty::UintTy::U8,
+            UintTy::U16 => rustc_ty::UintTy::U16,
+            UintTy::U32 => rustc_ty::UintTy::U32,
+            UintTy::U64 => rustc_ty::UintTy::U64,
+            UintTy::U128 => rustc_ty::UintTy::U128,
+        }
+    }
+}
+
+impl<'tcx> RustcInternal<'tcx> for FloatTy {
+    type T = rustc_ty::FloatTy;
+
+    fn internal(&self, _tables: &mut Tables<'tcx>) -> Self::T {
+        match self {
+            FloatTy::F32 => rustc_ty::FloatTy::F32,
+            FloatTy::F64 => rustc_ty::FloatTy::F64,
+        }
+    }
+}
+
 fn ty_const<'tcx>(constant: &Const, tables: &mut Tables<'tcx>) -> rustc_ty::Const<'tcx> {
     match constant.internal(tables) {
         rustc_middle::mir::Const::Ty(c) => c,
@@ -183,6 +259,13 @@ impl<'tcx> RustcInternal<'tcx> for ClosureKind {
     }
 }
 
+impl<'tcx> RustcInternal<'tcx> for AdtDef {
+    type T = rustc_ty::AdtDef<'tcx>;
+    fn internal(&self, tables: &mut Tables<'tcx>) -> Self::T {
+        tables.tcx.adt_def(self.0.internal(&mut *tables))
+    }
+}
+
 impl<'tcx, T> RustcInternal<'tcx> for &T
 where
     T: RustcInternal<'tcx>,

compiler/rustc_smir/src/rustc_smir/mod.rs

@@ -14,7 +14,7 @@ use rustc_hir::def::DefKind;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{alloc_range, AllocId};
 use rustc_middle::mir::mono::MonoItem;
-use rustc_middle::ty::{self, Instance, ParamEnv, Ty, TyCtxt, Variance};
+use rustc_middle::ty::{self, Instance, ParamEnv, ScalarInt, Ty, TyCtxt, Variance};
 use rustc_span::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_target::abi::FieldIdx;
 use stable_mir::mir::mono::InstanceDef;
@@ -24,7 +24,7 @@ use stable_mir::ty::{
     FloatTy, FnDef, GenericArgs, GenericParamDef, IntTy, LineInfo, Movability, RigidTy, Span,
     TyKind, UintTy,
 };
-use stable_mir::{self, opaque, Context, CrateItem, Filename, ItemKind};
+use stable_mir::{self, opaque, Context, CrateItem, Error, Filename, ItemKind};
 use std::cell::RefCell;
 use tracing::debug;
 
@@ -91,13 +91,14 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         new_item_kind(tables.tcx.def_kind(tables[item.0]))
     }
 
+    fn is_foreign_item(&self, item: CrateItem) -> bool {
+        let tables = self.0.borrow();
+        tables.tcx.is_foreign_item(tables[item.0])
+    }
+
     fn adt_kind(&self, def: AdtDef) -> AdtKind {
         let mut tables = self.0.borrow_mut();
-        let ty = tables.tcx.type_of(def.0.internal(&mut *tables)).instantiate_identity().kind();
-        let ty::TyKind::Adt(def, _) = ty else {
-            panic!("Expected an ADT definition, but found: {ty:?}")
-        };
-        def.adt_kind().stable(&mut *tables)
+        def.internal(&mut *tables).adt_kind().stable(&mut *tables)
     }
 
     fn def_ty(&self, item: stable_mir::DefId) -> stable_mir::ty::Ty {
@@ -302,6 +303,37 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
         let closure_kind = kind.internal(&mut *tables);
         Instance::resolve_closure(tables.tcx, def_id, args_ref, closure_kind).stable(&mut *tables)
     }
+
+    fn adt_is_box(&self, def: AdtDef) -> bool {
+        let mut tables = self.0.borrow_mut();
+        def.internal(&mut *tables).is_box()
+    }
+
+    fn eval_target_usize(&self, cnst: &Const) -> Result<u64, Error> {
+        let mut tables = self.0.borrow_mut();
+        let mir_const = cnst.internal(&mut *tables);
+        mir_const
+            .try_eval_target_usize(tables.tcx, ParamEnv::empty())
+            .ok_or_else(|| Error::new(format!("Const `{cnst:?}` cannot be encoded as u64")))
+    }
+
+    fn usize_to_const(&self, val: u64) -> Result<Const, Error> {
+        let mut tables = self.0.borrow_mut();
+        let ty = tables.tcx.types.usize;
+        let size = tables.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap().size;
+
+        let scalar = ScalarInt::try_from_uint(val, size).ok_or_else(|| {
+            Error::new(format!("Value overflow: cannot convert `{val}` to usize."))
+        })?;
+        Ok(ty::Const::new_value(tables.tcx, ty::ValTree::from_scalar_int(scalar), ty)
+            .stable(&mut *tables))
+    }
+
+    fn new_rigid_ty(&self, kind: RigidTy) -> stable_mir::ty::Ty {
+        let mut tables = self.0.borrow_mut();
+        let internal_kind = kind.internal(&mut *tables);
+        tables.tcx.mk_ty_from_kind(internal_kind).stable(&mut *tables)
+    }
 }
 
 pub(crate) struct TablesWrapper<'tcx>(pub(crate) RefCell<Tables<'tcx>>);

compiler/stable_mir/src/error.rs

@@ -8,6 +8,11 @@ use std::convert::From;
 use std::fmt::{Debug, Display, Formatter};
 use std::{error, fmt};
 
+macro_rules! error {
+     ($fmt: literal $(,)?) => { Error(format!($fmt)) };
+     ($fmt: literal, $($arg:tt)*) => { Error(format!($fmt, $($arg:tt)*)) };
+ }
+
 /// An error type used to represent an error that has already been reported by the compiler.
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub enum CompilerError<T> {
@@ -24,10 +29,10 @@ pub enum CompilerError<T> {
 
 /// A generic error to represent an API request that cannot be fulfilled.
 #[derive(Debug)]
-pub struct Error(String);
+pub struct Error(pub(crate) String);
 
 impl Error {
-    pub(crate) fn new(msg: String) -> Self {
+    pub fn new(msg: String) -> Self {
         Self(msg)
     }
 }

compiler/stable_mir/src/lib.rs

@@ -31,17 +31,18 @@ use self::ty::{
 #[macro_use]
 extern crate scoped_tls;
 
+#[macro_use]
 pub mod error;
 pub mod mir;
 pub mod ty;
 pub mod visitor;
 
 use crate::mir::pretty::function_name;
 use crate::mir::Mutability;
-use crate::ty::{AdtDef, AdtKind, ClosureDef, ClosureKind};
+use crate::ty::{AdtDef, AdtKind, ClosureDef, ClosureKind, Const, RigidTy};
 pub use error::*;
 use mir::mono::Instance;
-use ty::{Const, FnDef, GenericArgs};
+use ty::{FnDef, GenericArgs};
 
 /// Use String for now but we should replace it.
 pub type Symbol = String;
@@ -224,9 +225,24 @@ pub trait Context {
     /// Returns the `kind` of given `DefId`
     fn item_kind(&self, item: CrateItem) -> ItemKind;
 
+    /// Returns whether this is a foreign item.
+    fn is_foreign_item(&self, item: CrateItem) -> bool;
+
     /// Returns the kind of a given algebraic data type
     fn adt_kind(&self, def: AdtDef) -> AdtKind;
 
+    /// Returns if the ADT is a box.
+    fn adt_is_box(&self, def: AdtDef) -> bool;
+
+    /// Evaluate constant as a target usize.
+    fn eval_target_usize(&self, cnst: &Const) -> Result<u64, Error>;
+
+    /// Create a target usize constant for the given value.
+    fn usize_to_const(&self, val: u64) -> Result<Const, Error>;
+
+    /// Create a new type from the given kind.
+    fn new_rigid_ty(&self, kind: RigidTy) -> Ty;
+
     /// Returns the type of given crate item.
     fn def_ty(&self, item: DefId) -> Ty;
 

compiler/stable_mir/src/mir/body.rs

@@ -1,8 +1,10 @@
 use crate::mir::pretty::{function_body, pretty_statement};
-use crate::ty::{AdtDef, ClosureDef, Const, CoroutineDef, GenericArgs, Movability, Region, Ty};
-use crate::Opaque;
-use crate::Span;
+use crate::ty::{
+    AdtDef, ClosureDef, Const, CoroutineDef, GenericArgs, Movability, Region, RigidTy, Ty, TyKind,
+};
+use crate::{Error, Opaque, Span};
 use std::io;
+
 /// The SMIR representation of a single function.
 #[derive(Clone, Debug)]
 pub struct Body {
@@ -561,7 +563,7 @@ pub struct SwitchTarget {
     pub target: usize,
 }
 
-#[derive(Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum BorrowKind {
     /// Data must be immutable and is aliasable.
     Shared,
@@ -579,14 +581,14 @@ pub enum BorrowKind {
     },
 }
 
-#[derive(Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum MutBorrowKind {
     Default,
     TwoPhaseBorrow,
     ClosureCapture,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub enum Mutability {
     Not,
     Mut,
@@ -651,10 +653,16 @@ pub enum NullOp {
 }
 
 impl Operand {
-    pub fn ty(&self, locals: &[LocalDecl]) -> Ty {
+    /// Get the type of an operand relative to the local declaration.
+    ///
+    /// In order to retrieve the correct type, the `locals` argument must match the list of all
+    /// locals from the function body where this operand originates from.
+    ///
+    /// Errors indicate a malformed operand or incompatible locals list.
+    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
         match self {
             Operand::Copy(place) | Operand::Move(place) => place.ty(locals),
-            Operand::Constant(c) => c.ty(),
+            Operand::Constant(c) => Ok(c.ty()),
         }
     }
 }
@@ -666,12 +674,57 @@ impl Constant {
 }
 
 impl Place {
-    // FIXME(klinvill): This function is expected to resolve down the chain of projections to get
-    // the type referenced at the end of it. E.g. calling `ty()` on `*(_1.f)` should end up
-    // returning the type referenced by `f`. The information needed to do this may not currently be
-    // present in Stable MIR since at least an implementation for AdtDef is probably needed.
-    pub fn ty(&self, locals: &[LocalDecl]) -> Ty {
-        let _start_ty = locals[self.local].ty;
-        todo!("Implement projection")
+    /// Resolve down the chain of projections to get the type referenced at the end of it.
+    /// E.g.:
+    /// Calling `ty()` on `var.field` should return the type of `field`.
+    ///
+    /// In order to retrieve the correct type, the `locals` argument must match the list of all
+    /// locals from the function body where this place originates from.
+    pub fn ty(&self, locals: &[LocalDecl]) -> Result<Ty, Error> {
+        let start_ty = locals[self.local].ty;
+        self.projection.iter().fold(Ok(start_ty), |place_ty, elem| {
+            let ty = place_ty?;
+            match elem {
+                ProjectionElem::Deref => Self::deref_ty(ty),
+                ProjectionElem::Field(_idx, fty) => Ok(*fty),
+                ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => {
+                    Self::index_ty(ty)
+                }
+                ProjectionElem::Subslice { from, to, from_end } => {
+                    Self::subslice_ty(ty, from, to, from_end)
+                }
+                ProjectionElem::Downcast(_) => Ok(ty),
+                ProjectionElem::OpaqueCast(ty) | ProjectionElem::Subtype(ty) => Ok(*ty),
+            }
+        })
+    }
+
+    fn index_ty(ty: Ty) -> Result<Ty, Error> {
+        ty.kind().builtin_index().ok_or_else(|| error!("Cannot index non-array type: {ty:?}"))
+    }
+
+    fn subslice_ty(ty: Ty, from: &u64, to: &u64, from_end: &bool) -> Result<Ty, Error> {
+        let ty_kind = ty.kind();
+        match ty_kind {
+            TyKind::RigidTy(RigidTy::Slice(..)) => Ok(ty),
+            TyKind::RigidTy(RigidTy::Array(inner, _)) if !from_end => Ty::try_new_array(
+                inner,
+                to.checked_sub(*from).ok_or_else(|| error!("Subslice overflow: {from}..{to}"))?,
+            ),
+            TyKind::RigidTy(RigidTy::Array(inner, size)) => {
+                let size = size.eval_target_usize()?;
+                let len = size - from - to;
+                Ty::try_new_array(inner, len)
+            }
+            _ => Err(Error(format!("Cannot subslice non-array type: `{ty_kind:?}`"))),
+        }
+    }
+
+    fn deref_ty(ty: Ty) -> Result<Ty, Error> {
+        let deref_ty = ty
+            .kind()
+            .builtin_deref(true)
+            .ok_or_else(|| error!("Cannot dereference type: {ty:?}"))?;
+        Ok(deref_ty.ty)
     }
 }