Rollup merge of #58569 - kenta7777:reduce-code-repetition, r=oli-obk
Reduce Some Code Repetitions like `(n << amt) >> amt`
This Pull Request is related to [#49937](https://github.com/rust-lang/rust/issues/49937).
This Pull Request has reduced repetition of `(n << amt) >> amt`.
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 7da9070..c6902dd 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -10,6 +10,7 @@
GlobalId, AllocId, InboundsCheck,
ConstValue, Pointer, Scalar,
EvalResult, EvalErrorKind,
+ sign_extend, truncate,
};
use super::{
EvalContext, Machine, AllocMap, Allocation, AllocationExtra,
@@ -633,20 +634,17 @@
Err(_) => return err!(InvalidDiscriminant(raw_discr.erase_tag())),
};
let real_discr = if discr_val.layout.ty.is_signed() {
- let i = bits_discr as i128;
// going from layout tag type to typeck discriminant type
// requires first sign extending with the layout discriminant
- let shift = 128 - discr_val.layout.size.bits();
- let sexted = (i << shift) >> shift;
+ let sexted = sign_extend(bits_discr, discr_val.layout.size) as i128;
// and then zeroing with the typeck discriminant type
let discr_ty = rval.layout.ty
.ty_adt_def().expect("tagged layout corresponds to adt")
.repr
.discr_type();
- let discr_ty = layout::Integer::from_attr(self, discr_ty);
- let shift = 128 - discr_ty.size().bits();
+ let size = layout::Integer::from_attr(self, discr_ty).size();
let truncatee = sexted as u128;
- (truncatee << shift) >> shift
+ truncate(truncatee, size)
} else {
bits_discr
};
