Evaluate computed values to constants.

4 files changed, 18 insertions, 7 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/discriminant.rs b/compiler/rustc_const_eval/src/interpret/discriminant.rs
index 8dab45d65ee..fd173670374 100644
--- a/compiler/rustc_const_eval/src/interpret/discriminant.rs
+++ b/compiler/rustc_const_eval/src/interpret/discriminant.rs
@@ -1,7 +1,8 @@
 //! Functions for reading and writing discriminants of multi-variant layouts (enums and coroutines).
 
-use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout};
-use rustc_middle::{mir, ty};
+use rustc_middle::mir;
+use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt};
+use rustc_middle::ty::{self, Ty};
 use rustc_target::abi::{self, TagEncoding};
 use rustc_target::abi::{VariantIdx, Variants};
 
@@ -244,11 +245,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
     pub fn discriminant_for_variant(
         &self,
-        layout: TyAndLayout<'tcx>,
+        ty: Ty<'tcx>,
         variant: VariantIdx,
     ) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
-        let discr_layout = self.layout_of(layout.ty.discriminant_ty(*self.tcx))?;
-        let discr_value = match layout.ty.discriminant_for_variant(*self.tcx, variant) {
+        let discr_layout = self.layout_of(ty.discriminant_ty(*self.tcx))?;
+        let discr_value = match ty.discriminant_for_variant(*self.tcx, variant) {
             Some(discr) => {
                 // This type actually has discriminants.
                 assert_eq!(discr.ty, discr_layout.ty);
diff --git a/compiler/rustc_const_eval/src/interpret/intrinsics.rs b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
index c97207a61ac..c48857fcf3c 100644
--- a/compiler/rustc_const_eval/src/interpret/intrinsics.rs
+++ b/compiler/rustc_const_eval/src/interpret/intrinsics.rs
@@ -218,7 +218,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             sym::discriminant_value => {
                 let place = self.deref_pointer(&args[0])?;
                 let variant = self.read_discriminant(&place)?;
-                let discr = self.discriminant_for_variant(place.layout, variant)?;
+                let discr = self.discriminant_for_variant(place.layout.ty, variant)?;
                 self.write_immediate(*discr, dest)?;
             }
             sym::exact_div => {
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index 6716888290d..255dd1eba97 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -169,6 +169,16 @@ impl<'tcx, Prov: Provenance> ImmTy<'tcx, Prov> {
         ImmTy { imm: val.into(), layout }
     }
 
+    #[inline]
+    pub fn from_scalar_pair(a: Scalar<Prov>, b: Scalar<Prov>, layout: TyAndLayout<'tcx>) -> Self {
+        debug_assert!(
+            matches!(layout.abi, Abi::ScalarPair(..)),
+            "`ImmTy::from_scalar_pair` on non-scalar-pair layout"
+        );
+        let imm = Immediate::ScalarPair(a, b);
+        ImmTy { imm, layout }
+    }
+
     #[inline(always)]
     pub fn from_immediate(imm: Immediate<Prov>, layout: TyAndLayout<'tcx>) -> Self {
         debug_assert!(
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index 79cbda545f1..8c34d05042b 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -297,7 +297,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             Discriminant(place) => {
                 let op = self.eval_place_to_op(place, None)?;
                 let variant = self.read_discriminant(&op)?;
-                let discr = self.discriminant_for_variant(op.layout, variant)?;
+                let discr = self.discriminant_for_variant(op.layout.ty, variant)?;
                 self.write_immediate(*discr, &dest)?;
             }
         }