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generalize truncate and sign_extend to take a Size

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This commit is contained in:
Ralf Jung 2018-08-14 20:38:30 +02:00
parent ad2de8b4ee
commit 7483ea8176
2 changed files with 10 additions and 9 deletions
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5
src/librustc_mir/hair/pattern/mod.rs
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@ -1085,8 +1085,9 @@ pub fn compare_const_vals<'a, 'tcx>(
},
ty::TyInt(_) => {
let layout = tcx.layout_of(ty).ok()?;
let a = interpret::sign_extend(a, layout);
let b = interpret::sign_extend(b, layout);
assert!(layout.abi.is_signed());
let a = interpret::sign_extend(a, layout.size);
let b = interpret::sign_extend(b, layout.size);
Some((a as i128).cmp(&(b as i128)))
},
_ => Some(a.cmp(&b)),

14
src/librustc_mir/interpret/eval_context.rs
View File

@ -1020,11 +1020,12 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M
}
pub fn sign_extend(&self, value: u128, ty: TyLayout<'_>) -> u128 {
super::sign_extend(value, ty)
assert!(ty.abi.is_signed());
super::sign_extend(value, ty.size)
}
pub fn truncate(&self, value: u128, ty: TyLayout<'_>) -> u128 {
super::truncate(value, ty)
super::truncate(value, ty.size)
}
fn dump_field_name(&self, s: &mut String, ty: Ty<'tcx>, i: usize, variant: usize) -> ::std::fmt::Result {
@ -1095,9 +1096,8 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M
}
}
pub fn sign_extend(value: u128, layout: TyLayout<'_>) -> u128 {
let size = layout.size.bits();
assert!(layout.abi.is_signed());
pub fn sign_extend(value: u128, size: Size) -> u128 {
let size = size.bits();
// sign extend
let shift = 128 - size;
// shift the unsigned value to the left
@ -1105,8 +1105,8 @@ pub fn sign_extend(value: u128, layout: TyLayout<'_>) -> u128 {
(((value << shift) as i128) >> shift) as u128
}
pub fn truncate(value: u128, layout: TyLayout<'_>) -> u128 {
let size = layout.size.bits();
pub fn truncate(value: u128, size: Size) -> u128 {
let size = size.bits();
let shift = 128 - size;
// truncate (shift left to drop out leftover values, shift right to fill with zeroes)
(value << shift) >> shift