Change `const_field` and `const_caller_location` to return `ConstValue`...

Change `const_field` and `const_caller_location` to return `ConstValue` instead of `Const` as the type
in the returned const isn't needed.

src/librustc/query/mod.rs

@@ -517,7 +517,7 @@ fn describe_as_module(def_id: DefId, tcx: TyCtxt<'_>) -> String {
         /// Extracts a field of a (variant of a) const.
         query const_field(
             key: ty::ParamEnvAnd<'tcx, (&'tcx ty::Const<'tcx>, mir::Field)>
-        ) -> &'tcx ty::Const<'tcx> {
+        ) -> ConstValue<'tcx> {
             no_force
             desc { "extract field of const" }
         }
@@ -531,7 +531,7 @@ fn describe_as_module(def_id: DefId, tcx: TyCtxt<'_>) -> String {
             desc { "destructure constant" }
         }
 
-        query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> &'tcx ty::Const<'tcx> {
+        query const_caller_location(key: (rustc_span::Symbol, u32, u32)) -> ConstValue<'tcx> {
             no_force
             desc { "get a &core::panic::Location referring to a span" }
         }

src/librustc/ty/query/mod.rs

@@ -14,7 +14,7 @@
 use crate::middle::stability::{self, DeprecationEntry};
 use crate::mir;
 use crate::mir::interpret::GlobalId;
-use crate::mir::interpret::{ConstEvalRawResult, ConstEvalResult};
+use crate::mir::interpret::{ConstEvalRawResult, ConstEvalResult, ConstValue};
 use crate::mir::interpret::{LitToConstError, LitToConstInput};
 use crate::mir::mono::CodegenUnit;
 use crate::session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};

src/librustc_codegen_llvm/intrinsic.rs

@@ -193,8 +193,7 @@ fn codegen_intrinsic_call(
                     .tcx
                     .const_eval_instance(ty::ParamEnv::reveal_all(), instance, None)
                     .unwrap();
-                let const_ = ty::Const { val: ty::ConstKind::Value(ty_name), ty: ret_ty };
-                OperandRef::from_const(self, &const_).immediate_or_packed_pair(self)
+                OperandRef::from_const(self, ty_name, ret_ty).immediate_or_packed_pair(self)
             }
             "init" => {
                 let ty = substs.type_at(0);

src/librustc_codegen_ssa/mir/block.rs

@@ -991,7 +991,7 @@ fn get_caller_location(&mut self, bx: &mut Bx, span: Span) -> OperandRef<'tcx, B
                 caller.line as u32,
                 caller.col_display as u32 + 1,
             ));
-            OperandRef::from_const(bx, const_loc)
+            OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
         })
     }
 

src/librustc_codegen_ssa/mir/constant.rs

 use crate::mir::operand::OperandRef;
 use crate::traits::*;
 use rustc::mir;
-use rustc::mir::interpret::ErrorHandled;
+use rustc::mir::interpret::{ConstValue, ErrorHandled};
 use rustc::ty::layout::{self, HasTyCtxt};
 use rustc::ty::{self, Ty};
 use rustc_index::vec::Idx;
@@ -30,7 +30,7 @@ pub fn eval_mir_constant_to_operand(
             }
             _ => {
                 let val = self.eval_mir_constant(constant)?;
-                Ok(OperandRef::from_const(bx, &val))
+                Ok(OperandRef::from_const(bx, val.clone(), constant.literal.ty))
             }
         }
     }
@@ -38,19 +38,13 @@ pub fn eval_mir_constant_to_operand(
     pub fn eval_mir_constant(
         &mut self,
         constant: &mir::Constant<'tcx>,
-    ) -> Result<&'tcx ty::Const<'tcx>, ErrorHandled> {
+    ) -> Result<ConstValue<'tcx>, ErrorHandled> {
         match constant.literal.val {
             ty::ConstKind::Unevaluated(def_id, substs, promoted) => {
                 let substs = self.monomorphize(&substs);
                 self.cx
                     .tcx()
                     .const_eval_resolve(ty::ParamEnv::reveal_all(), def_id, substs, promoted, None)
-                    .map(|val| {
-                        self.cx.tcx().mk_const(ty::Const {
-                            val: ty::ConstKind::Value(val),
-                            ty: constant.literal.ty,
-                        })
-                    })
                     .map_err(|err| {
                         if promoted.is_none() {
                             self.cx
@@ -61,7 +55,15 @@ pub fn eval_mir_constant(
                         err
                     })
             }
-            _ => Ok(self.monomorphize(&constant.literal)),
+            ty::ConstKind::Value(value) => Ok(value),
+            _ => {
+                let const_ = self.monomorphize(&constant.literal);
+                if let ty::ConstKind::Value(value) = const_.val {
+                    Ok(value)
+                } else {
+                    bug!("encountered bad ConstKind in codegen");
+                }
+            }
         }
     }
 
@@ -71,21 +73,22 @@ pub fn simd_shuffle_indices(
         bx: &Bx,
         span: Span,
         ty: Ty<'tcx>,
-        constant: Result<&'tcx ty::Const<'tcx>, ErrorHandled>,
+        constant: Result<ConstValue<'tcx>, ErrorHandled>,
     ) -> (Bx::Value, Ty<'tcx>) {
         constant
-            .map(|c| {
-                let field_ty = c.ty.builtin_index().unwrap();
-                let fields = match c.ty.kind {
+            .map(|val| {
+                let field_ty = ty.builtin_index().unwrap();
+                let fields = match ty.kind {
                     ty::Array(_, n) => n.eval_usize(bx.tcx(), ty::ParamEnv::reveal_all()),
-                    _ => bug!("invalid simd shuffle type: {}", c.ty),
+                    _ => bug!("invalid simd shuffle type: {}", ty),
                 };
+                let c = bx.tcx().mk_const(ty::Const { val: ty::ConstKind::Value(val), ty });
                 let values: Vec<_> = (0..fields)
                     .map(|field| {
                         let field = bx.tcx().const_field(
                             ty::ParamEnv::reveal_all().and((&c, mir::Field::new(field as usize))),
                         );
-                        if let Some(prim) = field.val.try_to_scalar() {
+                        if let Some(prim) = field.try_to_scalar() {
                             let layout = bx.layout_of(field_ty);
                             let scalar = match layout.abi {
                                 layout::Abi::Scalar(ref x) => x,

src/librustc_codegen_ssa/mir/operand.rs

@@ -8,8 +8,8 @@
 
 use rustc::mir;
 use rustc::mir::interpret::{ConstValue, ErrorHandled, Pointer, Scalar};
-use rustc::ty;
 use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout};
+use rustc::ty::Ty;
 
 use std::fmt;
 
@@ -66,20 +66,16 @@ pub fn new_zst<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
 
     pub fn from_const<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
         bx: &mut Bx,
-        val: &ty::Const<'tcx>,
+        val: ConstValue<'tcx>,
+        ty: Ty<'tcx>,
     ) -> Self {
-        let layout = bx.layout_of(val.ty);
+        let layout = bx.layout_of(ty);
 
         if layout.is_zst() {
             return OperandRef::new_zst(bx, layout);
         }
 
-        let val_val = match val.val {
-            ty::ConstKind::Value(val_val) => val_val,
-            _ => bug!("encountered bad ConstKind in codegen"),
-        };
-
-        let val = match val_val {
+        let val = match val {
             ConstValue::Scalar(x) => {
                 let scalar = match layout.abi {
                     layout::Abi::Scalar(ref x) => x,

src/librustc_mir/const_eval.rs

@@ -26,7 +26,7 @@ pub(crate) fn const_field<'tcx>(
     variant: Option<VariantIdx>,
     field: mir::Field,
     value: &'tcx ty::Const<'tcx>,
-) -> &'tcx ty::Const<'tcx> {
+) -> ConstValue<'tcx> {
     trace!("const_field: {:?}, {:?}", field, value);
     let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
     // get the operand again
@@ -40,26 +40,19 @@ pub(crate) fn const_field<'tcx>(
     let field = ecx.operand_field(down, field.index() as u64).unwrap();
     // and finally move back to the const world, always normalizing because
     // this is not called for statics.
-    let val = op_to_const(&ecx, field);
-    tcx.mk_const(ty::Const { val: ty::ConstKind::Value(val), ty: op.layout.ty })
+    op_to_const(&ecx, field)
 }
 
 pub(crate) fn const_caller_location<'tcx>(
     tcx: TyCtxt<'tcx>,
     (file, line, col): (Symbol, u32, u32),
-) -> &'tcx ty::Const<'tcx> {
+) -> ConstValue<'tcx> {
     trace!("const_caller_location: {}:{}:{}", file, line, col);
     let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::reveal_all(), false);
 
-    let loc_ty = tcx.caller_location_ty();
     let loc_place = ecx.alloc_caller_location(file, line, col);
     intern_const_alloc_recursive(&mut ecx, InternKind::Constant, loc_place, false).unwrap();
-    let loc_const = ty::Const {
-        ty: loc_ty,
-        val: ty::ConstKind::Value(ConstValue::Scalar(loc_place.ptr.into())),
-    };
-
-    tcx.mk_const(loc_const)
+    ConstValue::Scalar(loc_place.ptr.into())
 }
 
 // this function uses `unwrap` copiously, because an already validated constant