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Simplify lit_to_mir_constant a bit

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This commit is contained in:
bjorn3 2025-03-12 13:39:26 +01:00
parent c58c06a6f5
commit 8dc0c0ece9
1 changed files with 11 additions and 16 deletions
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27
compiler/rustc_mir_build/src/builder/expr/as_constant.rs
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@ -105,23 +105,19 @@ fn lit_to_mir_constant<'tcx>(tcx: TyCtxt<'tcx>, lit_input: LitToConstInput<'tcx>
return Const::Ty(Ty::new_error(tcx, guar), ty::Const::new_error(tcx, guar));
}
let trunc = |n, width: ty::UintTy| {
let width = width
.normalize(tcx.data_layout.pointer_size.bits().try_into().unwrap())
.bit_width()
.unwrap();
let width = Size::from_bits(width);
let lit_ty = match *ty.kind() {
ty::Pat(base, _) => base,
_ => ty,
};
let trunc = |n| {
let width = lit_ty.primitive_size(tcx);
trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
let result = width.truncate(n);
trace!("trunc result: {}", result);
ConstValue::Scalar(Scalar::from_uint(result, width))
};
let lit_ty = match *ty.kind() {
ty::Pat(base, _) => base,
_ => ty,
};
let value = match (lit, lit_ty.kind()) {
(ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
let s = s.as_str();
@ -149,11 +145,10 @@ fn lit_to_mir_constant<'tcx>(tcx: TyCtxt<'tcx>, lit_input: LitToConstInput<'tcx>
(ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
}
(ast::LitKind::Int(n, _), ty::Uint(ui)) if !neg => trunc(n.get(), *ui),
(ast::LitKind::Int(n, _), ty::Int(i)) => trunc(
if neg { (n.get() as i128).overflowing_neg().0 as u128 } else { n.get() },
i.to_unsigned(),
),
(ast::LitKind::Int(n, _), ty::Uint(_)) if !neg => trunc(n.get()),
(ast::LitKind::Int(n, _), ty::Int(_)) => {
trunc(if neg { (n.get() as i128).overflowing_neg().0 as u128 } else { n.get() })
}
(ast::LitKind::Float(n, _), ty::Float(fty)) => {
parse_float_into_constval(*n, *fty, neg).unwrap()
}