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Deduplicate some code

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This commit is contained in:
Oliver Schneider 2018-02-22 09:37:20 +01:00
parent df283df887
commit 889a4ebfa9
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1 changed files with 67 additions and 73 deletions
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140
src/librustc/ty/mod.rs
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@ -1823,64 +1823,77 @@ impl<'a, 'gcx, 'tcx> AdtDef {
} }
} }
#[inline]
fn eval_explicit_discr(
&self,
tcx: TyCtxt<'a, 'gcx, 'tcx>,
expr_did: DefId,
) -> Option<Discr<'tcx>> {
let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
let repr_type = self.repr.discr_type();
let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did);
let instance = ty::Instance::new(expr_did, substs);
let cid = GlobalId {
instance,
promoted: None
};
match tcx.const_eval(param_env.and(cid)) {
Ok(&ty::Const {
val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
..
}) => {
trace!("discriminants: {} ({:?})", b, repr_type);
let ty = repr_type.to_ty(tcx);
if ty.is_signed() {
let (ty, param_env) = tcx
.lift_to_global(&(ty, param_env))
.unwrap_or_else(|| {
bug!("MIR: discriminants({:?}, {:?}) got \
type with inference types/regions",
ty, param_env);
});
let size = tcx.global_tcx()
.layout_of(param_env.and(ty))
.expect("int layout")
.size
.bits();
let val = b as i128;
// sign extend to i128
let amt = 128 - size;
let val = (val << amt) >> amt;
Some(Discr {
val: val as u128,
ty,
})
} else {
Some(Discr {
val: b,
ty,
})
}
}
_ => {
if !expr_did.is_local() {
span_bug!(tcx.def_span(expr_did),
"variant discriminant evaluation succeeded \
in its crate but failed locally");
}
None
}
}
}
#[inline] #[inline]
pub fn discriminants(&'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>) pub fn discriminants(&'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>)
-> impl Iterator<Item=Discr<'tcx>> + 'a { -> impl Iterator<Item=Discr<'tcx>> + 'a {
let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
let repr_type = self.repr.discr_type(); let repr_type = self.repr.discr_type();
let initial = repr_type.initial_discriminant(tcx.global_tcx()); let initial = repr_type.initial_discriminant(tcx.global_tcx());
let mut prev_discr = None::<Discr<'tcx>>; let mut prev_discr = None::<Discr<'tcx>>;
self.variants.iter().map(move |v| { self.variants.iter().map(move |v| {
let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
if let VariantDiscr::Explicit(expr_did) = v.discr { if let VariantDiscr::Explicit(expr_did) = v.discr {
let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did); if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
let instance = ty::Instance::new(expr_did, substs); discr = new_discr;
let cid = GlobalId {
instance,
promoted: None
};
match tcx.const_eval(param_env.and(cid)) {
Ok(&ty::Const {
val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
..
}) => {
trace!("discriminants: {} ({:?})", b, repr_type);
let ty = repr_type.to_ty(tcx);
if ty.is_signed() {
let (ty, param_env) = tcx
.lift_to_global(&(ty, param_env))
.unwrap_or_else(|| {
bug!("MIR: discriminants({:?}, {:?}) got \
type with inference types/regions",
ty, param_env);
});
let size = tcx.global_tcx()
.layout_of(param_env.and(ty))
.expect("int layout")
.size
.bits();
let val = b as i128;
// sign extend to i128
let amt = 128 - size;
let val = (val << amt) >> amt;
discr = Discr {
val: val as u128,
ty,
};
} else {
discr = Discr {
val: b,
ty,
};
}
}
_ => {
if !expr_did.is_local() {
span_bug!(tcx.def_span(expr_did),
"variant discriminant evaluation succeeded \
in its crate but failed locally");
}
}
} }
} }
prev_discr = Some(discr); prev_discr = Some(discr);
@ -1898,7 +1911,6 @@ impl<'a, 'gcx, 'tcx> AdtDef {
tcx: TyCtxt<'a, 'gcx, 'tcx>, tcx: TyCtxt<'a, 'gcx, 'tcx>,
variant_index: usize) variant_index: usize)
-> Discr<'tcx> { -> Discr<'tcx> {
let param_env = ParamEnv::empty(traits::Reveal::UserFacing);
let repr_type = self.repr.discr_type(); let repr_type = self.repr.discr_type();
let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx()); let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx());
let mut explicit_index = variant_index; let mut explicit_index = variant_index;
@ -1909,30 +1921,12 @@ impl<'a, 'gcx, 'tcx> AdtDef {
explicit_index -= distance; explicit_index -= distance;
} }
ty::VariantDiscr::Explicit(expr_did) => { ty::VariantDiscr::Explicit(expr_did) => {
let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did); match self.eval_explicit_discr(tcx, expr_did) {
let instance = ty::Instance::new(expr_did, substs); Some(discr) => {
let cid = GlobalId { explicit_value = discr;
instance,
promoted: None
};
match tcx.const_eval(param_env.and(cid)) {
Ok(&ty::Const {
val: ConstVal::Value(Value::ByVal(PrimVal::Bytes(b))),
..
}) => {
trace!("discriminants: {} ({:?})", b, repr_type);
explicit_value = Discr {
val: b,
ty: repr_type.to_ty(tcx),
};
break; break;
} },
_ => { None => {
if !expr_did.is_local() {
span_bug!(tcx.def_span(expr_did),
"variant discriminant evaluation succeeded \
in its crate but failed locally");
}
if explicit_index == 0 { if explicit_index == 0 {
break; break;
} }