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u128 truncation and sign extension are not just interpreter related

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oli
2020-11-04 13:41:58 +00:00
parent e67c768110
commit abacaf2aef
18 changed files with 73 additions and 89 deletions
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11
compiler/rustc_middle/src/ty/util.rs
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@@ -2,7 +2,6 @@
use crate::ich::NodeIdHashingMode;
use crate::middle::codegen_fn_attrs::CodegenFnAttrFlags;
use crate::mir::interpret::{sign_extend, truncate};
use crate::ty::fold::TypeFolder;
use crate::ty::layout::IntegerExt;
use crate::ty::query::TyCtxtAt;
@@ -38,7 +37,7 @@ impl<'tcx> fmt::Display for Discr<'tcx> {
let size = ty::tls::with(|tcx| Integer::from_attr(&tcx, SignedInt(ity)).size());
let x = self.val;
// sign extend the raw representation to be an i128
let x = sign_extend(x, size) as i128;
let x = size.sign_extend(x) as i128;
write!(fmt, "{}", x)
}
_ => write!(fmt, "{}", self.val),
@@ -47,7 +46,7 @@ impl<'tcx> fmt::Display for Discr<'tcx> {
}
fn signed_min(size: Size) -> i128 {
sign_extend(1_u128 << (size.bits() - 1), size) as i128
size.sign_extend(1_u128 << (size.bits() - 1)) as i128
}
fn signed_max(size: Size) -> i128 {
@@ -77,14 +76,14 @@ impl<'tcx> Discr<'tcx> {
let (val, oflo) = if signed {
let min = signed_min(size);
let max = signed_max(size);
let val = sign_extend(self.val, size) as i128;
let val = size.sign_extend(self.val) as i128;
assert!(n < (i128::MAX as u128));
let n = n as i128;
let oflo = val > max - n;
let val = if oflo { min + (n - (max - val) - 1) } else { val + n };
// zero the upper bits
let val = val as u128;
let val = truncate(val, size);
let val = size.truncate(val);
(val, oflo)
} else {
let max = unsigned_max(size);
@@ -650,7 +649,7 @@ impl<'tcx> ty::TyS<'tcx> {
let val = match self.kind() {
ty::Int(_) | ty::Uint(_) => {
let (size, signed) = int_size_and_signed(tcx, self);
let val = if signed { truncate(signed_min(size) as u128, size) } else { 0 };
let val = if signed { size.truncate(signed_min(size) as u128) } else { 0 };
Some(val)
}
ty::Char => Some(0),