bjoernager/rust
bjoernager/rust
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This commit is contained in:
varkor 2018-05-23 21:16:07 +01:00
parent a9f2c5a7b2
commit effb3d05a0
1 changed files with 17 additions and 11 deletions
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28
src/librustc_mir/hair/pattern/_match.rs
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@ -470,20 +470,21 @@ fn all_constructors<'a, 'tcx: 'a>(cx: &mut MatchCheckCtxt<'a, 'tcx>,
]
}
ty::TyInt(_) if exhaustive_integer_patterns => {
let size = cx.tcx.layout_of(ty::ParamEnv::reveal_all().and(pcx.ty))
// FIXME(49937): refactor these bit manipulations into interpret.
let bits = cx.tcx.layout_of(ty::ParamEnv::reveal_all().and(pcx.ty))
.unwrap().size.bits() as u128;
let min = (1u128 << (size - 1)).wrapping_neg();
let max = (1u128 << (size - 1)).wrapping_sub(1);
let min = 1u128 << (bits - 1);
let max = (1u128 << (bits - 1)) - 1;
value_constructors = true;
vec![ConstantRange(ty::Const::from_bits(cx.tcx, min as u128, pcx.ty),
ty::Const::from_bits(cx.tcx, max as u128, pcx.ty),
RangeEnd::Included)]
}
ty::TyUint(_) if exhaustive_integer_patterns => {
let size = cx.tcx.layout_of(ty::ParamEnv::reveal_all().and(pcx.ty))
// FIXME(49937): refactor these bit manipulations into interpret.
let bits = cx.tcx.layout_of(ty::ParamEnv::reveal_all().and(pcx.ty))
.unwrap().size.bits() as u32;
let shift = 1u128.overflowing_shl(size);
let max = shift.0.wrapping_sub(1 + (shift.1 as u128));
let max = (!0u128).wrapping_shr(128 - bits);
value_constructors = true;
vec![ConstantRange(ty::Const::from_bits(cx.tcx, 0u128, pcx.ty),
ty::Const::from_bits(cx.tcx, max as u128, pcx.ty),
@ -603,8 +604,12 @@ fn max_slice_length<'p, 'a: 'p, 'tcx: 'a, I>(
}
/// An inclusive interval, used for precise integer exhaustiveness checking.
/// `Interval`s always store a contiguous range of integers. That means that
/// signed integers are offset (see `offset_sign`) by their minimum value.
/// `Interval`s always store a contiguous range of integers. This means that
/// signed values are encoded by offsetting them such that `0` represents the
/// minimum value for the integer, regardless of sign.
/// For example, the range `-128...127` is encoded as `0...255`.
/// This makes comparisons and arithmetic on interval endpoints much more
/// straightforward. See `offset_sign` for the conversion technique.
struct Interval<'tcx> {
pub range: RangeInclusive<u128>,
pub ty: Ty<'tcx>,
@ -661,10 +666,11 @@ impl<'tcx> Interval<'tcx> {
let (lo, hi) = range.into_inner();
match ty.sty {
ty::TyInt(_) => {
let size = tcx.layout_of(ty::ParamEnv::reveal_all().and(ty))
// FIXME(49937): refactor these bit manipulations into interpret.
let bits = tcx.layout_of(ty::ParamEnv::reveal_all().and(ty))
.unwrap().size.bits() as u128;
let min = (1u128 << (size - 1)).wrapping_neg();
let shift = 1u128.overflowing_shl(size as u32);
let min = 1u128 << (bits - 1);
let shift = 1u128.overflowing_shl(bits as u32);
let mask = shift.0.wrapping_sub(1 + (shift.1 as u128));
if encode {
let offset = |x: u128| x.wrapping_sub(min) & mask;