change thir to use mir::ConstantKind instead of ty::Const

compiler/rustc_middle/src/mir/mod.rs

@@ -9,13 +9,13 @@ use crate::ty::adjustment::PointerCast;
 use crate::ty::codec::{TyDecoder, TyEncoder};
 use crate::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeVisitor};
 use crate::ty::print::{FmtPrinter, Printer};
-use crate::ty::subst::{Subst, SubstsRef};
+use crate::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use crate::ty::{self, List, Ty, TyCtxt};
 use crate::ty::{AdtDef, InstanceDef, Region, ScalarInt, UserTypeAnnotationIndex};
 
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def::{CtorKind, Namespace};
-use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
+use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::{self, GeneratorKind};
 use rustc_hir::{self as hir, HirId};
 use rustc_session::Session;
@@ -2664,6 +2664,16 @@ impl<'tcx> ConstantKind<'tcx> {
         }
     }
 
+    pub fn try_val(&self) -> Option<ConstValue<'tcx>> {
+        match self {
+            ConstantKind::Ty(c) => match c.val() {
+                ty::ConstKind::Value(v) => Some(v),
+                _ => None,
+            },
+            ConstantKind::Val(v, _) => Some(*v),
+        }
+    }
+
     #[inline]
     pub fn try_to_value(self) -> Option<interpret::ConstValue<'tcx>> {
         match self {
@@ -2692,6 +2702,32 @@ impl<'tcx> ConstantKind<'tcx> {
         self.try_to_scalar_int()?.try_into().ok()
     }
 
+    #[inline]
+    pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
+        match self {
+            Self::Ty(c) => {
+                // FIXME Need to use a different evaluation function that directly returns a `ConstValue`
+                // if evaluation succeeds and does not create a ValTree first
+                if let Some(val) = c.val().try_eval(tcx, param_env) {
+                    match val {
+                        Ok(val) => Self::Val(val, c.ty()),
+                        Err(ErrorReported) => Self::Ty(tcx.const_error(self.ty())),
+                    }
+                } else {
+                    self
+                }
+            }
+            Self::Val(_, _) => self,
+        }
+    }
+
+    #[inline]
+    /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
+    pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
+        self.try_eval_bits(tcx, param_env, ty)
+            .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
+    }
+
     #[inline]
     pub fn try_eval_bits(
         &self,
@@ -2726,25 +2762,181 @@ impl<'tcx> ConstantKind<'tcx> {
         }
     }
 
+    pub fn from_bits(
+        tcx: TyCtxt<'tcx>,
+        bits: u128,
+        param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
+    ) -> Self {
+        let size = tcx
+            .layout_of(param_env_ty)
+            .unwrap_or_else(|e| {
+                bug!("could not compute layout for {:?}: {:?}", param_env_ty.value, e)
+            })
+            .size;
+        let cv = ConstValue::Scalar(Scalar::from_uint(bits, size));
+
+        Self::Val(cv, param_env_ty.value)
+    }
+
     pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
         let cv = ConstValue::from_bool(v);
         Self::Val(cv, tcx.types.bool)
     }
 
-    pub fn from_zero_sized(ty: Ty<'tcx>) -> Self {
+    pub fn zero_sized(ty: Ty<'tcx>) -> Self {
         let cv = ConstValue::Scalar(Scalar::ZST);
         Self::Val(cv, ty)
     }
 
     pub fn from_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
         let ty = tcx.types.usize;
-        let size = tcx
-            .layout_of(ty::ParamEnv::empty().and(ty))
-            .unwrap_or_else(|e| bug!("could not compute layout for {:?}: {:?}", ty, e))
-            .size;
-        let cv = ConstValue::Scalar(Scalar::from_uint(n as u128, size));
+        Self::from_bits(tcx, n as u128, ty::ParamEnv::empty().and(ty))
+    }
 
-        Self::Val(cv, ty)
+    #[instrument(skip(tcx), level = "debug")]
+    pub fn try_eval_lit_or_param(
+        tcx: TyCtxt<'tcx>,
+        ty: Ty<'tcx>,
+        expr: &'tcx hir::Expr<'tcx>,
+    ) -> Option<Self> {
+        // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
+        // currently have to be wrapped in curly brackets, so it's necessary to special-case.
+        let expr = match &expr.kind {
+            hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
+                block.expr.as_ref().unwrap()
+            }
+            _ => expr,
+        };
+
+        let lit_input = match expr.kind {
+            hir::ExprKind::Lit(ref lit) => {
+                Some(interpret::LitToConstInput { lit: &lit.node, ty, neg: false })
+            }
+            hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
+                hir::ExprKind::Lit(ref lit) => {
+                    Some(interpret::LitToConstInput { lit: &lit.node, ty, neg: true })
+                }
+                _ => None,
+            },
+            _ => None,
+        };
+
+        if let Some(lit_input) = lit_input {
+            // If an error occurred, ignore that it's a literal and leave reporting the error up to
+            // mir.
+            match tcx.at(expr.span).lit_to_mir_constant(lit_input) {
+                Ok(c) => return Some(c),
+                Err(e) => {
+                    tcx.sess.delay_span_bug(
+                        expr.span,
+                        &format!("Const::from_anon_const: couldn't lit_to_const {:?}", e),
+                    );
+                }
+            }
+        }
+        use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
+        match expr.kind {
+            ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
+                // Find the name and index of the const parameter by indexing the generics of
+                // the parent item and construct a `ParamConst`.
+                let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+                let item_id = tcx.hir().get_parent_node(hir_id);
+                let item_def_id = tcx.hir().local_def_id(item_id);
+                let generics = tcx.generics_of(item_def_id.to_def_id());
+                let index = generics.param_def_id_to_index[&def_id];
+                let name = tcx.hir().name(hir_id);
+                let ty_const = tcx.mk_const(ty::ConstS {
+                    val: ty::ConstKind::Param(ty::ParamConst::new(index, name)),
+                    ty,
+                });
+
+                Some(Self::Ty(ty_const))
+            }
+            _ => None,
+        }
+    }
+
+    #[instrument(skip(tcx), level = "debug")]
+    pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
+        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+
+        let body_id = match tcx.hir().get(hir_id) {
+            hir::Node::AnonConst(ac) => ac.body,
+            _ => span_bug!(
+                tcx.def_span(def_id.to_def_id()),
+                "from_inline_const can only process anonymous constants"
+            ),
+        };
+
+        let expr = &tcx.hir().body(body_id).value;
+
+        let ty = tcx.typeck(def_id).node_type(hir_id);
+
+        let ret = match Self::try_eval_lit_or_param(tcx, ty, expr) {
+            Some(v) => v,
+            None => {
+                let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
+                let parent_substs =
+                    tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
+                let substs = ty::InlineConstSubsts::new(
+                    tcx,
+                    ty::InlineConstSubstsParts { parent_substs, ty },
+                )
+                .substs;
+                let ty_const = tcx.mk_const(ty::ConstS {
+                    val: ty::ConstKind::Unevaluated(ty::Unevaluated {
+                        def: ty::WithOptConstParam::unknown(def_id).to_global(),
+                        substs,
+                        promoted: None,
+                    }),
+                    ty,
+                });
+
+                Self::Ty(ty_const)
+            }
+        };
+        debug_assert!(!ret.has_free_regions());
+        ret
+    }
+
+    /// Literals are converted to `ConstantKindVal`, const generic parameters are eagerly
+    /// converted to a constant, everything else becomes `Unevaluated`.
+    pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
+        Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id))
+    }
+
+    #[instrument(skip(tcx), level = "debug")]
+    fn from_opt_const_arg_anon_const(
+        tcx: TyCtxt<'tcx>,
+        def: ty::WithOptConstParam<LocalDefId>,
+    ) -> Self {
+        let body_id = match tcx.hir().get_by_def_id(def.did) {
+            hir::Node::AnonConst(ac) => ac.body,
+            _ => span_bug!(
+                tcx.def_span(def.did.to_def_id()),
+                "from_anon_const can only process anonymous constants"
+            ),
+        };
+
+        let expr = &tcx.hir().body(body_id).value;
+        debug!(?expr);
+
+        let ty = tcx.type_of(def.def_id_for_type_of());
+
+        match Self::try_eval_lit_or_param(tcx, ty, expr) {
+            Some(v) => v,
+            None => {
+                let ty_const = tcx.mk_const(ty::ConstS {
+                    val: ty::ConstKind::Unevaluated(ty::Unevaluated {
+                        def: def.to_global(),
+                        substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
+                        promoted: None,
+                    }),
+                    ty,
+                });
+                Self::Ty(ty_const)
+            }
+        }
     }
 }
 

compiler/rustc_middle/src/mir/query.rs

@@ -1,6 +1,6 @@
 //! Values computed by queries that use MIR.
 
-use crate::mir::{Body, Promoted};
+use crate::mir::{self, Body, Promoted};
 use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt};
 use rustc_data_structures::stable_map::FxHashMap;
 use rustc_data_structures::vec_map::VecMap;
@@ -421,6 +421,13 @@ pub struct DestructuredConst<'tcx> {
     pub fields: &'tcx [ty::Const<'tcx>],
 }
 
+/// The constituent parts of an ADT or array.
+#[derive(Copy, Clone, Debug, HashStable)]
+pub struct DestructuredMirConstant<'tcx> {
+    pub variant: Option<VariantIdx>,
+    pub fields: &'tcx [mir::ConstantKind<'tcx>],
+}
+
 /// Coverage information summarized from a MIR if instrumented for source code coverage (see
 /// compiler option `-Cinstrument-coverage`). This information is generated by the
 /// `InstrumentCoverage` MIR pass and can be retrieved via the `coverageinfo` query.

compiler/rustc_middle/src/query/mod.rs

@@ -940,6 +940,13 @@ rustc_queries! {
         remap_env_constness
     }
 
+    /// Destructure an `mir::ConstantKind` ADT or array into its variant index
+    /// and its field values.
+    query destructure_mir_constant(key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>) -> mir::DestructuredMirConstant<'tcx> {
+        desc { "destructure mir constant"}
+        remap_env_constness
+    }
+
     /// Dereference a constant reference or raw pointer and turn the result into a constant
     /// again.
     query deref_const(
@@ -949,6 +956,15 @@ rustc_queries! {
         remap_env_constness
     }
 
+    /// Dereference a constant reference or raw pointer and turn the result into a constant
+    /// again.
+    query deref_mir_constant(
+        key: ty::ParamEnvAnd<'tcx, mir::ConstantKind<'tcx>>
+    ) -> mir::ConstantKind<'tcx> {
+        desc { "deref constant" }
+        remap_env_constness
+    }
+
     query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> ConstValue<'tcx> {
         desc { "get a &core::panic::Location referring to a span" }
     }
@@ -960,6 +976,10 @@ rustc_queries! {
         desc { "converting literal to const" }
     }
 
+    query lit_to_mir_constant(key: LitToConstInput<'tcx>) -> Result<mir::ConstantKind<'tcx>, LitToConstError> {
+        desc { "converting literal to mir constant" }
+    }
+
     query check_match(key: DefId) {
         desc { |tcx| "match-checking `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }

compiler/rustc_middle/src/thir.rs

@@ -19,11 +19,11 @@ use rustc_middle::infer::canonical::Canonical;
 use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::AllocId;
 use rustc_middle::mir::{
-    BinOp, BorrowKind, FakeReadCause, Field, Mutability, UnOp, UserTypeProjection,
+    self, BinOp, BorrowKind, FakeReadCause, Field, Mutability, UnOp, UserTypeProjection,
 };
 use rustc_middle::ty::adjustment::PointerCast;
 use rustc_middle::ty::subst::SubstsRef;
-use rustc_middle::ty::{self, AdtDef, Const, Ty, UpvarSubsts, UserType};
+use rustc_middle::ty::{self, AdtDef, Ty, UpvarSubsts, UserType};
 use rustc_middle::ty::{
     CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
 };
@@ -193,7 +193,7 @@ pub enum StmtKind<'tcx> {
 
 // `Expr` is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(Expr<'_>, 104);
+rustc_data_structures::static_assert_size!(Expr<'_>, 144);
 
 /// A THIR expression.
 #[derive(Debug, HashStable)]
@@ -375,7 +375,7 @@ pub enum ExprKind<'tcx> {
     /// An array literal constructed from one repeated element, e.g. `[1; 5]`.
     Repeat {
         value: ExprId,
-        count: Const<'tcx>,
+        count: ty::Const<'tcx>,
     },
     /// An array, e.g. `[a, b, c, d]`.
     Array {
@@ -522,7 +522,7 @@ pub enum InlineAsmOperand<'tcx> {
         out_expr: Option<ExprId>,
     },
     Const {
-        value: Const<'tcx>,
+        value: mir::ConstantKind<'tcx>,
         span: Span,
     },
     SymFn {
@@ -661,7 +661,7 @@ pub enum PatKind<'tcx> {
     /// * Opaque constants, that must not be matched structurally. So anything that does not derive
     ///   `PartialEq` and `Eq`.
     Constant {
-        value: ty::Const<'tcx>,
+        value: mir::ConstantKind<'tcx>,
     },
 
     Range(PatRange<'tcx>),
@@ -691,8 +691,8 @@ pub enum PatKind<'tcx> {
 
 #[derive(Copy, Clone, Debug, PartialEq, HashStable)]
 pub struct PatRange<'tcx> {
-    pub lo: ty::Const<'tcx>,
-    pub hi: ty::Const<'tcx>,
+    pub lo: mir::ConstantKind<'tcx>,
+    pub hi: mir::ConstantKind<'tcx>,
     pub end: RangeEnd,
 }
 

compiler/rustc_middle/src/thir/abstract_const.rs

@@ -22,7 +22,7 @@ pub enum CastKind {
 /// A node of an `AbstractConst`.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
 pub enum Node<'tcx> {
-    Leaf(ty::Const<'tcx>),
+    Leaf(mir::ConstantKind<'tcx>),
     Binop(mir::BinOp, NodeId, NodeId),
     UnaryOp(mir::UnOp, NodeId),
     FunctionCall(NodeId, &'tcx [NodeId]),

compiler/rustc_middle/src/thir/visit.rs

@@ -1,6 +1,8 @@
 use super::{
     Arm, Block, Expr, ExprKind, Guard, InlineAsmOperand, Pat, PatKind, Stmt, StmtKind, Thir,
 };
+use crate::mir::ConstantKind;
+use crate::ty::Const;
 
 pub trait Visitor<'a, 'tcx: 'a>: Sized {
     fn thir(&self) -> &'a Thir<'tcx>;
@@ -24,6 +26,8 @@ pub trait Visitor<'a, 'tcx: 'a>: Sized {
     fn visit_pat(&mut self, pat: &Pat<'tcx>) {
         walk_pat(self, pat);
     }
+
+    fn visit_constant(&mut self, _constant: ConstantKind<'tcx>) {}
 }
 
 pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Expr<'tcx>) {
@@ -90,8 +94,13 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
                 visitor.visit_expr(&visitor.thir()[value])
             }
         }
+<<<<<<< HEAD
         ConstBlock { did: _, substs: _ } => {}
         Repeat { value, count: _ } => {
+=======
+        ConstBlock { value } => visitor.visit_constant(value),
+        Repeat { value, count } => {
+>>>>>>> 6064f16d846 (change thir to use mir::ConstantKind instead of ty::Const)
             visitor.visit_expr(&visitor.thir()[value]);
         }
         Array { ref fields } | Tuple { ref fields } => {

compiler/rustc_middle/src/ty/consts/kind.rs

@@ -126,7 +126,7 @@ impl<'tcx> ConstKind<'tcx> {
     #[inline]
     /// Tries to evaluate the constant if it is `Unevaluated`. If that isn't possible or necessary
     /// return `None`.
-    pub(super) fn try_eval(
+    pub fn try_eval(
         self,
         tcx: TyCtxt<'tcx>,
         param_env: ParamEnv<'tcx>,

compiler/rustc_middle/src/ty/util.rs

@@ -662,8 +662,8 @@ impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> {
 impl<'tcx> Ty<'tcx> {
     /// Returns the maximum value for the given numeric type (including `char`s)
     /// or returns `None` if the type is not numeric.
-    pub fn numeric_max_val(self, tcx: TyCtxt<'tcx>) -> Option<Const<'tcx>> {
-        let val = match self.kind() {
+    pub fn numeric_max_val(self, tcx: TyCtxt<'tcx>) -> Option<u128> {
+        match self.kind() {
             ty::Int(_) | ty::Uint(_) => {
                 let (size, signed) = int_size_and_signed(tcx, self);
                 let val =
@@ -676,14 +676,13 @@ impl<'tcx> Ty<'tcx> {
                 ty::FloatTy::F64 => rustc_apfloat::ieee::Double::INFINITY.to_bits(),
             }),
             _ => None,
-        };
-        val.map(|v| Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self)))
+        }
     }
 
     /// Returns the minimum value for the given numeric type (including `char`s)
     /// or returns `None` if the type is not numeric.
-    pub fn numeric_min_val(self, tcx: TyCtxt<'tcx>) -> Option<Const<'tcx>> {
-        let val = match self.kind() {
+    pub fn numeric_min_val(self, tcx: TyCtxt<'tcx>) -> Option<u128> {
+        match self.kind() {
             ty::Int(_) | ty::Uint(_) => {
                 let (size, signed) = int_size_and_signed(tcx, self);
                 let val = if signed { size.truncate(size.signed_int_min() as u128) } else { 0 };
@@ -695,8 +694,7 @@ impl<'tcx> Ty<'tcx> {
                 ty::FloatTy::F64 => (-::rustc_apfloat::ieee::Double::INFINITY).to_bits(),
             }),
             _ => None,
-        };
-        val.map(|v| Const::from_bits(tcx, v, ty::ParamEnv::empty().and(self)))
+        }
     }
 
     /// Checks whether values of this type `T` are *moved* or *copied*