do the variant idx computations on the host (non-overflowing)
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 94fbd4a..9e7ae32 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -687,24 +687,22 @@
(dataful_variant.as_u32() as u128, dataful_variant)
},
Ok(raw_discr) => {
+ // We need to use machine arithmetic to get the relative variant idx.
let discr_layout = self.layout_of(discr_layout.value.to_int_ty(*self.tcx))?;
let discr_val = ImmTy::from_uint(raw_discr, discr_layout);
- // We need to use machine arithmetic.
let niche_start_val = ImmTy::from_uint(niche_start, discr_layout);
- let variants_start_val = ImmTy::from_uint(variants_start, discr_layout);
let variant_index_relative_val = self.binary_op(
mir::BinOp::Sub,
discr_val,
niche_start_val,
)?;
- let variant_index_val = self.binary_op(
- mir::BinOp::Add,
- variant_index_relative_val,
- variants_start_val,
- )?;
- let variant_index = variant_index_val
+ let variant_index_relative = variant_index_relative_val
.to_scalar()?
.assert_bits(discr_val.layout.size);
+ // Then computing the absolute variant idx should not overflow any more.
+ let variant_index = variants_start
+ .checked_add(variant_index_relative)
+ .expect("oveflow computing absolute variant idx");
// Check if this is in the range that indicates an actual discriminant.
if variants_start <= variant_index && variant_index <= variants_end {
let index = variant_index as usize;
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index 9a3d701..5f4903d 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -1060,17 +1060,15 @@
variant_index.as_usize() < dest.layout.ty.ty_adt_def().unwrap().variants.len(),
);
if variant_index != dataful_variant {
- let discr_layout = self.layout_of(discr_layout.value.to_int_ty(*self.tcx))?;
- // We need to use machine arithmetic.
let variants_start = niche_variants.start().as_u32();
- let variants_start_val = ImmTy::from_uint(variants_start, discr_layout);
+ let variant_index_relative = variant_index.as_u32()
+ .checked_sub(variants_start)
+ .expect("overflow computing relative variant idx");
+ // We need to use machine arithmetic when taking into account `niche_start`.
+ let discr_layout = self.layout_of(discr_layout.value.to_int_ty(*self.tcx))?;
let niche_start_val = ImmTy::from_uint(niche_start, discr_layout);
- let variant_index_val = ImmTy::from_uint(variant_index.as_u32(), discr_layout);
- let variant_index_relative_val = self.binary_op(
- mir::BinOp::Sub,
- variant_index_val,
- variants_start_val,
- )?;
+ let variant_index_relative_val =
+ ImmTy::from_uint(variant_index_relative, discr_layout);
let discr_val = self.binary_op(
mir::BinOp::Add,
variant_index_relative_val,
