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Make trans::adt know that some structs are unsized

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This commit is contained in:
Nick Cameron 2014-11-04 11:37:18 +13:00
parent ceeac26de8
commit 04dd61d1ec
3 changed files with 23 additions and 27 deletions
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45
src/librustc/middle/trans/adt.rs
View File

@ -49,6 +49,7 @@ use std::num::Int;
use std::rc::Rc;
use llvm::{ValueRef, True, IntEQ, IntNE};
use back::abi::slice_elt_base;
use middle::subst;
use middle::subst::Subst;
use middle::trans::_match;
@ -235,7 +236,7 @@ fn represent_type_uncached(cx: &CrateContext, t: ty::t) -> Repr {
if cases[1 - discr].is_zerolen(cx, t) {
let st = mk_struct(cx, cases[discr].tys.as_slice(),
false, t);
match cases[discr].find_ptr() {
match cases[discr].find_ptr(cx) {
Some(ThinPointer(_)) if st.fields.len() == 1 => {
return RawNullablePointer {
nndiscr: discr as Disr,
@ -290,7 +291,7 @@ struct Case {
#[deriving(Eq, PartialEq, Show)]
pub enum PointerField {
ThinPointer(uint),
FatPointer(uint, uint)
FatPointer(uint)
}
impl Case {
@ -298,31 +299,22 @@ impl Case {
mk_struct(cx, self.tys.as_slice(), false, scapegoat).size == 0
}
fn find_ptr(&self) -> Option<PointerField> {
use back::abi::{fn_field_code, slice_elt_base, trt_field_box};
fn find_ptr(&self, cx: &CrateContext) -> Option<PointerField> {
for (i, &ty) in self.tys.iter().enumerate() {
match ty::get(ty).sty {
// &T/&mut T could either be a thin or fat pointer depending on T
ty::ty_rptr(_, ty::mt { ty, .. }) => match ty::get(ty).sty {
// &T/&mut T/Box<T> could either be a thin or fat pointer depending on T
ty::ty_rptr(_, ty::mt { ty, .. }) | ty::ty_uniq(ty) => match ty::get(ty).sty {
// &[T] and &str are a pointer and length pair
ty::ty_vec(_, None) | ty::ty_str => return Some(FatPointer(i, slice_elt_base)),
ty::ty_vec(_, None) | ty::ty_str => return Some(FatPointer(i)),
// &Trait/&mut Trait are a pair of pointers: the actual object and a vtable
ty::ty_trait(..) => return Some(FatPointer(i, trt_field_box)),
// &Trait is a pair of pointers: the actual object and a vtable
ty::ty_trait(..) => return Some(FatPointer(i)),
// Any other &T/&mut T is just a pointer
_ => return Some(ThinPointer(i))
},
ty::ty_struct(..) if !ty::type_is_sized(cx.tcx(), ty) => {
return Some(FatPointer(i))
}
// Box<T> could either be a thin or fat pointer depending on T
ty::ty_uniq(t) => match ty::get(t).sty {
ty::ty_vec(_, None) => return Some(FatPointer(i, slice_elt_base)),
// Box<Trait> is a pair of pointers: the actual object and a vtable
ty::ty_trait(..) => return Some(FatPointer(i, trt_field_box)),
// Any other Box<T> is just a pointer
// Any other &T is just a pointer
_ => return Some(ThinPointer(i))
},
@ -330,7 +322,7 @@ impl Case {
ty::ty_bare_fn(..) => return Some(ThinPointer(i)),
// Closures are a pair of pointers: the code and environment
ty::ty_closure(..) => return Some(FatPointer(i, fn_field_code)),
ty::ty_closure(..) => return Some(FatPointer(i)),
// Anything else is not a pointer
_ => continue
@ -636,6 +628,7 @@ pub fn trans_get_discr(bcx: Block, r: &Repr, scrutinee: ValueRef, cast_to: Optio
-> ValueRef {
let signed;
let val;
debug!("trans_get_discr r: {}", r);
match *r {
CEnum(ity, min, max) => {
val = load_discr(bcx, ity, scrutinee, min, max);
@ -671,7 +664,7 @@ fn struct_wrapped_nullable_bitdiscr(bcx: Block, nndiscr: Disr, ptrfield: Pointer
scrutinee: ValueRef) -> ValueRef {
let llptrptr = match ptrfield {
ThinPointer(field) => GEPi(bcx, scrutinee, [0, field]),
FatPointer(field, pair) => GEPi(bcx, scrutinee, [0, field, pair])
FatPointer(field) => GEPi(bcx, scrutinee, [0, field, slice_elt_base])
};
let llptr = Load(bcx, llptrptr);
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
@ -767,8 +760,8 @@ pub fn trans_set_discr(bcx: Block, r: &Repr, val: ValueRef, discr: Disr) {
ThinPointer(field) =>
(GEPi(bcx, val, [0, field]),
type_of::type_of(bcx.ccx(), nonnull.fields[field])),
FatPointer(field, pair) => {
let v = GEPi(bcx, val, [0, field, pair]);
FatPointer(field) => {
let v = GEPi(bcx, val, [0, field, slice_elt_base]);
(v, val_ty(v).element_type())
}
};
@ -1102,7 +1095,7 @@ pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef)
StructWrappedNullablePointer { nndiscr, ptrfield, .. } => {
let (idx, sub_idx) = match ptrfield {
ThinPointer(field) => (field, None),
FatPointer(field, pair) => (field, Some(pair))
FatPointer(field) => (field, Some(slice_elt_base))
};
if is_null(const_struct_field(ccx, val, idx, sub_idx)) {
/* subtraction as uint is ok because nndiscr is either 0 or 1 */

2
src/librustc/middle/trans/debuginfo.rs
View File

@ -2255,7 +2255,7 @@ impl EnumMemberDescriptionFactory {
let null_variant_name = token::get_name((*self.variants)[null_variant_index].name);
let discrfield = match ptrfield {
adt::ThinPointer(field) => format!("{}", field),
adt::FatPointer(field, pair) => format!("{}${}", field, pair)
adt::FatPointer(field) => format!("{}", field)
};
let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
discrfield,

3
src/librustc_back/abi.rs
View File

@ -14,6 +14,9 @@ pub const box_field_refcnt: uint = 0u;
pub const box_field_drop_glue: uint = 1u;
pub const box_field_body: uint = 4u;
// FIXME(18590) although we have three different layouts here, the compiler relies on
// them being the same. We should replace them with one set of constants.
// The two halves of a closure: code and environment.
pub const fn_field_code: uint = 0u;
pub const fn_field_box: uint = 1u;