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

5 files changed, 174 insertions, 22 deletions

diff --git a/compiler/stable_mir/src/error.rs b/compiler/stable_mir/src/error.rs
index 19910691456..1ff65717e87 100644
--- a/compiler/stable_mir/src/error.rs
+++ b/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)
     }
 }
diff --git a/compiler/stable_mir/src/lib.rs b/compiler/stable_mir/src/lib.rs
index 79102dcce35..91f1066d720 100644
--- a/compiler/stable_mir/src/lib.rs
+++ b/compiler/stable_mir/src/lib.rs
@@ -31,6 +31,7 @@ use self::ty::{
 #[macro_use]
 extern crate scoped_tls;
 
+#[macro_use]
 pub mod error;
 pub mod mir;
 pub mod ty;
@@ -38,10 +39,10 @@ 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;
 
diff --git a/compiler/stable_mir/src/mir/body.rs b/compiler/stable_mir/src/mir/body.rs
index fa58a7ffe15..8cdb054de9a 100644
--- a/compiler/stable_mir/src/mir/body.rs
+++ b/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, Span, Opaque};
 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 +674,51 @@ 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 => {
+                    let deref_ty = ty
+                        .kind()
+                        .builtin_deref(true)
+                        .ok_or_else(|| error!("Cannot dereference type: {ty:?}"))?;
+                    Ok(deref_ty.ty)
+                }
+                ProjectionElem::Field(_idx, fty) => Ok(*fty),
+                ProjectionElem::Index(_) | ProjectionElem::ConstantIndex { .. } => ty
+                    .kind()
+                    .builtin_index()
+                    .ok_or_else(|| error!("Cannot index non-array type: {ty:?}")),
+                ProjectionElem::Subslice { from, to, from_end } => {
+                    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:?}`"))),
+                    }
+                }
+                ProjectionElem::Downcast(_) => Ok(ty),
+                ProjectionElem::OpaqueCast(ty) | ProjectionElem::Subtype(ty) => Ok(*ty),
+            }
+        })
     }
 }
diff --git a/compiler/stable_mir/src/mir/mono.rs b/compiler/stable_mir/src/mir/mono.rs
index 8562bfd3905..8c43f2c4b8f 100644
--- a/compiler/stable_mir/src/mir/mono.rs
+++ b/compiler/stable_mir/src/mir/mono.rs
@@ -1,7 +1,7 @@
 use crate::mir::Body;
 use crate::ty::{ClosureDef, ClosureKind, FnDef, GenericArgs, IndexedVal, Ty};
 use crate::{with, CrateItem, DefId, Error, ItemKind, Opaque};
-use std::fmt::Debug;
+use std::fmt::{Debug, Formatter};
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum MonoItem {
@@ -10,7 +10,7 @@ pub enum MonoItem {
     GlobalAsm(Opaque),
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Instance {
     /// The type of instance.
     pub kind: InstanceKind,
@@ -83,6 +83,15 @@ impl Instance {
     }
 }
 
+impl Debug for Instance {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Instance")
+            .field("kind", &self.kind)
+            .field("def", &self.mangled_name())
+            .finish()
+    }
+}
+
 /// Try to convert a crate item into an instance.
 /// The item cannot be generic in order to be converted into an instance.
 impl TryFrom<CrateItem> for Instance {
diff --git a/compiler/stable_mir/src/ty.rs b/compiler/stable_mir/src/ty.rs
index fa932c5d81a..f0b11dce9aa 100644
--- a/compiler/stable_mir/src/ty.rs
+++ b/compiler/stable_mir/src/ty.rs
@@ -1,7 +1,7 @@
 use super::{
     mir::Safety,
     mir::{Body, Mutability},
-    with, AllocId, DefId, Symbol,
+    with, AllocId, DefId, Error, Symbol,
 };
 use crate::{Filename, Opaque};
 use std::fmt::{self, Debug, Display, Formatter};
@@ -15,6 +15,21 @@ impl Debug for Ty {
     }
 }
 
+/// Constructors for `Ty`.
+impl Ty {
+    /// Create a new type from a given kind.
+    ///
+    /// Note that not all types may be supported at this point.
+    fn from_rigid_kind(kind: RigidTy) -> Ty {
+        with(|cx| cx.new_rigid_ty(kind))
+    }
+
+    /// Create a new array type.
+    pub fn try_new_array(elem_ty: Ty, size: u64) -> Result<Ty, Error> {
+        Ok(Ty::from_rigid_kind(RigidTy::Array(elem_ty, Const::try_from_target_usize(size)?)))
+    }
+}
+
 impl Ty {
     pub fn kind(&self) -> TyKind {
         with(|context| context.ty_kind(*self))
@@ -47,6 +62,16 @@ impl Const {
     pub fn ty(&self) -> Ty {
         self.ty
     }
+
+    /// Creates an interned usize constant.
+    fn try_from_target_usize(val: u64) -> Result<Self, Error> {
+        with(|cx| cx.usize_to_const(val))
+    }
+
+    /// Try to evaluate to a target `usize`.
+    pub fn eval_target_usize(&self) -> Result<u64, Error> {
+        with(|cx| cx.eval_target_usize(self))
+    }
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -173,6 +198,38 @@ impl TyKind {
             None
         }
     }
+
+    /// Returns the type of `ty[i]` for builtin types.
+    pub fn builtin_index(&self) -> Option<Ty> {
+        match self.rigid()? {
+            RigidTy::Array(ty, _) | RigidTy::Slice(ty) => Some(*ty),
+            _ => None,
+        }
+    }
+
+    /// Returns the type and mutability of `*ty` for builtin types.
+    ///
+    /// The parameter `explicit` indicates if this is an *explicit* dereference.
+    /// Some types -- notably unsafe ptrs -- can only be dereferenced explicitly.
+    pub fn builtin_deref(&self, explicit: bool) -> Option<TypeAndMut> {
+        match self.rigid()? {
+            RigidTy::Adt(def, args) if def.is_box() => {
+                Some(TypeAndMut { ty: *args.0.first()?.ty()?, mutability: Mutability::Not })
+            }
+            RigidTy::Ref(_, ty, mutability) => {
+                Some(TypeAndMut { ty: *ty, mutability: *mutability })
+            }
+            RigidTy::RawPtr(ty, mutability) if explicit => {
+                Some(TypeAndMut { ty: *ty, mutability: *mutability })
+            }
+            _ => None,
+        }
+    }
+}
+
+pub struct TypeAndMut {
+    pub ty: Ty,
+    pub mutability: Mutability,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]
@@ -199,6 +256,12 @@ pub enum RigidTy {
     CoroutineWitness(CoroutineWitnessDef, GenericArgs),
 }
 
+impl From<RigidTy> for TyKind {
+    fn from(value: RigidTy) -> Self {
+        TyKind::RigidTy(value)
+    }
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum IntTy {
     Isize,
@@ -269,6 +332,10 @@ impl AdtDef {
     pub fn kind(&self) -> AdtKind {
         with(|cx| cx.adt_kind(*self))
     }
+
+    pub fn is_box(&self) -> bool {
+        with(|cx| cx.adt_is_box(*self))
+    }
 }
 
 impl Display for AdtKind {
@@ -363,6 +430,14 @@ impl GenericArgKind {
             _ => panic!("{self:?}"),
         }
     }
+
+    /// Return the generic argument type if applicable, otherwise return `None`.
+    pub fn ty(&self) -> Option<&Ty> {
+        match self {
+            GenericArgKind::Type(ty) => Some(ty),
+            _ => None,
+        }
+    }
 }
 
 #[derive(Clone, Debug, Eq, PartialEq)]