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thestingerthestinger
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remove reference counting headers from ~
Unique pointers and vectors currently contain a reference counting header when containing a managed pointer. This `{ ref_count, type_desc, prev, next }` header is not necessary and not a sensible foundation for tracing. It adds needless complexity to library code and is responsible for breakage in places where the branch has been left out. The `borrow_offset` field can now be removed from `TyDesc` along with the associated handling in the compiler. Closes #9510 Closes #11533
1 parent 9075025 commit 0e885e4

22 files changed

+152
-148
lines changed

‎src/librustc/middle/trans/_match.rs

Lines changed: 2 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1584,14 +1584,9 @@ fn compile_submatch_continue<'r,
15841584
}
15851585

15861586
if any_uniq_pat(m, col) {
1587-
let pat_ty = node_id_type(bcx, pat_id);
15881587
let llbox = Load(bcx, val);
1589-
let unboxed = match ty::get(pat_ty).sty {
1590-
ty::ty_uniq(..) if !ty::type_contents(bcx.tcx(), pat_ty).owns_managed() => llbox,
1591-
_ => GEPi(bcx, llbox, [0u, abi::box_field_body])
1592-
};
15931588
compile_submatch(bcx, enter_uniq(bcx, dm, m, col, val),
1594-
vec::append(~[unboxed], vals_left), chk);
1589+
vec::append(~[llbox], vals_left), chk);
15951590
return;
15961591
}
15971592

@@ -2231,13 +2226,8 @@ fn bind_irrefutable_pat<'a>(
22312226
}
22322227
}
22332228
ast::PatUniq(inner) => {
2234-
let pat_ty = node_id_type(bcx, pat.id);
22352229
let llbox = Load(bcx, val);
2236-
let unboxed = match ty::get(pat_ty).sty {
2237-
ty::ty_uniq(..) if !ty::type_contents(bcx.tcx(), pat_ty).owns_managed() => llbox,
2238-
_ => GEPi(bcx, llbox, [0u, abi::box_field_body])
2239-
};
2240-
bcx = bind_irrefutable_pat(bcx, inner, unboxed, binding_mode);
2230+
bcx = bind_irrefutable_pat(bcx, inner, llbox, binding_mode);
22412231
}
22422232
ast::PatRegion(inner) => {
22432233
let loaded_val = Load(bcx, val);

‎src/librustc/middle/trans/base.rs

Lines changed: 2 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -358,7 +358,7 @@ pub fn malloc_raw_dyn<'a>(
358358
} else {
359359
// we treat ~fn, @fn and @[] as @ here, which isn't ideal
360360
let langcall = match heap {
361-
heap_managed | heap_managed_unique => {
361+
heap_managed => {
362362
require_alloc_fn(bcx, t, MallocFnLangItem)
363363
}
364364
heap_exchange_closure => {
@@ -382,9 +382,7 @@ pub fn malloc_raw_dyn<'a>(
382382
langcall,
383383
[tydesc, size],
384384
None);
385-
let r = rslt(r.bcx, PointerCast(r.bcx, r.val, llty));
386-
maybe_set_managed_unique_rc(r.bcx, r.val, heap);
387-
r
385+
rslt(r.bcx, PointerCast(r.bcx, r.val, llty))
388386
}
389387
}
390388

@@ -431,27 +429,6 @@ pub fn malloc_general<'a>(bcx: &'a Block, t: ty::t, heap: heap)
431429
malloc_general_dyn(bcx, t, heap, llsize_of(bcx.ccx(), ty))
432430
}
433431

434-
pub fn heap_for_unique(bcx: &Block, t: ty::t) -> heap {
435-
if ty::type_contents(bcx.tcx(), t).owns_managed() {
436-
heap_managed_unique
437-
} else {
438-
heap_exchange
439-
}
440-
}
441-
442-
pub fn maybe_set_managed_unique_rc(bcx: &Block, bx: ValueRef, heap: heap) {
443-
assert!(heap != heap_exchange);
444-
if heap == heap_managed_unique {
445-
// In cases where we are looking at a unique-typed allocation in the
446-
// managed heap (thus have refcount 1 from the managed allocator),
447-
// such as a ~(@foo) or such. These need to have their refcount forced
448-
// to -2 so the annihilator ignores them.
449-
let rc = GEPi(bcx, bx, [0u, abi::box_field_refcnt]);
450-
let rc_val = C_int(bcx.ccx(), -2);
451-
Store(bcx, rc_val, rc);
452-
}
453-
}
454-
455432
// Type descriptor and type glue stuff
456433

457434
pub fn get_tydesc_simple(ccx: &CrateContext, t: ty::t) -> ValueRef {

‎src/librustc/middle/trans/closure.rs

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -150,14 +150,6 @@ pub fn mk_closure_tys(tcx: ty::ctxt,
150150
return cdata_ty;
151151
}
152152

153-
fn heap_for_unique_closure(bcx: &Block, t: ty::t) -> heap {
154-
if ty::type_contents(bcx.tcx(), t).owns_managed() {
155-
heap_managed_unique
156-
} else {
157-
heap_exchange_closure
158-
}
159-
}
160-
161153
pub fn allocate_cbox<'a>(
162154
bcx: &'a Block<'a>,
163155
sigil: ast::Sigil,
@@ -173,7 +165,7 @@ pub fn allocate_cbox<'a>(
173165
tcx.sess.bug("trying to trans allocation of @fn")
174166
}
175167
ast::OwnedSigil => {
176-
malloc_raw(bcx, cdata_ty, heap_for_unique_closure(bcx, cdata_ty))
168+
malloc_raw(bcx, cdata_ty, heap_exchange_closure)
177169
}
178170
ast::BorrowedSigil => {
179171
let cbox_ty = tuplify_box_ty(tcx, cdata_ty);

‎src/librustc/middle/trans/common.rs

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -316,7 +316,6 @@ pub fn warn_not_to_commit(ccx: &CrateContext, msg: &str) {
316316
#[deriving(Eq)]
317317
pub enum heap {
318318
heap_managed,
319-
heap_managed_unique,
320319
heap_exchange,
321320
heap_exchange_closure
322321
}
@@ -498,7 +497,7 @@ pub fn add_clean_temp_mem_in_scope_(bcx: &Block, scope_id: Option<ast::NodeId>,
498497

499498
pub fn add_clean_free(cx: &Block, ptr: ValueRef, heap: heap) {
500499
let free_fn = match heap {
501-
heap_managed | heap_managed_unique => {
500+
heap_managed => {
502501
@GCHeapFreeingCleanupFunction {
503502
ptr: ptr,
504503
} as @CleanupFunction

‎src/librustc/middle/trans/datum.rs

Lines changed: 1 addition & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -570,19 +570,14 @@ impl Datum {
570570
let (content_ty, header) = match ty::get(self.ty).sty {
571571
ty::ty_box(typ) => (typ, true),
572572
ty::ty_uniq(typ) => (typ, false),
573-
ty::ty_vec(_, ty::vstore_uniq) | ty::ty_str(ty::vstore_uniq) => {
574-
let unit_ty = ty::sequence_element_type(bcx.tcx(), self.ty);
575-
let unboxed_vec_ty = ty::mk_mut_unboxed_vec(bcx.tcx(), unit_ty);
576-
(unboxed_vec_ty, true)
577-
}
578573
_ => {
579574
bcx.tcx().sess.bug(format!(
580575
"box_body() invoked on non-box type {}",
581576
ty_to_str(bcx.tcx(), self.ty)));
582577
}
583578
};
584579

585-
if !header && !ty::type_contents(bcx.tcx(), content_ty).owns_managed() {
580+
if !header {
586581
let ptr = self.to_value_llval(bcx);
587582
let ty = type_of::type_of(bcx.ccx(), content_ty);
588583
let body = PointerCast(bcx, ptr, ty.ptr_to());

‎src/librustc/middle/trans/debuginfo.rs

Lines changed: 2 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -2147,10 +2147,6 @@ fn type_metadata(cx: &CrateContext,
21472147
ty::vstore_fixed(len) => {
21482148
fixed_vec_metadata(cx, mt.ty, len, usage_site_span)
21492149
}
2150-
ty::vstore_uniq if ty::type_contents(cx.tcx, mt.ty).owns_managed() => {
2151-
let boxed_vec_metadata = boxed_vec_metadata(cx, mt.ty, usage_site_span);
2152-
pointer_type_metadata(cx, t, boxed_vec_metadata)
2153-
}
21542150
ty::vstore_uniq => {
21552151
let vec_metadata = vec_metadata(cx, mt.ty, usage_site_span);
21562152
pointer_type_metadata(cx, t, vec_metadata)
@@ -2165,12 +2161,8 @@ fn type_metadata(cx: &CrateContext,
21652161
}
21662162
},
21672163
ty::ty_uniq(typ) => {
2168-
if ty::type_contents(cx.tcx, typ).owns_managed() {
2169-
create_pointer_to_box_metadata(cx, t, typ)
2170-
} else {
2171-
let pointee = type_metadata(cx, typ, usage_site_span);
2172-
pointer_type_metadata(cx, t, pointee)
2173-
}
2164+
let pointee = type_metadata(cx, typ, usage_site_span);
2165+
pointer_type_metadata(cx, t, pointee)
21742166
}
21752167
ty::ty_ptr(ref mt) | ty::ty_rptr(_, ref mt) => {
21762168
let pointee = type_metadata(cx, mt.ty, usage_site_span);

‎src/librustc/middle/trans/expr.rs

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -608,16 +608,15 @@ fn trans_rvalue_datum_unadjusted<'a>(bcx: &'a Block<'a>, expr: &ast::Expr)
608608
expr, contents);
609609
}
610610
ast::ExprVstore(contents, ast::ExprVstoreUniq) => {
611-
let heap = heap_for_unique(bcx, expr_ty(bcx, contents));
612-
return tvec::trans_uniq_or_managed_vstore(bcx, heap,
611+
return tvec::trans_uniq_or_managed_vstore(bcx, heap_exchange,
613612
expr, contents);
614613
}
615614
ast::ExprBox(_, contents) => {
616615
// Special case for `~T`. (The other case, for GC, is handled in
617616
// `trans_rvalue_dps_unadjusted`.)
618617
let box_ty = expr_ty(bcx, expr);
619618
let contents_ty = expr_ty(bcx, contents);
620-
let heap = heap_for_unique(bcx, contents_ty);
619+
let heap = heap_exchange;
621620
return trans_boxed_expr(bcx, box_ty, contents, contents_ty, heap)
622621
}
623622
ast::ExprLit(lit) => {
@@ -1461,8 +1460,7 @@ fn trans_unary_datum<'a>(
14611460
trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap_managed)
14621461
}
14631462
ast::UnUniq => {
1464-
let heap = heap_for_unique(bcx, un_ty);
1465-
trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap)
1463+
trans_boxed_expr(bcx, un_ty, sub_expr, sub_ty, heap_exchange)
14661464
}
14671465
ast::UnDeref => {
14681466
bcx.sess().bug("deref expressions should have been \

‎src/librustc/middle/trans/glue.rs

Lines changed: 1 addition & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -303,11 +303,7 @@ pub fn make_free_glue<'a>(bcx: &'a Block<'a>, v: ValueRef, t: ty::t)
303303
with_cond(bcx, not_null, |bcx| {
304304
let body_datum = box_datum.box_body(bcx);
305305
let bcx = drop_ty(bcx, body_datum.to_ref_llval(bcx), body_datum.ty);
306-
if ty::type_contents(bcx.tcx(), t).owns_managed() {
307-
trans_free(bcx, box_datum.val)
308-
} else {
309-
trans_exchange_free(bcx, box_datum.val)
310-
}
306+
trans_exchange_free(bcx, box_datum.val)
311307
})
312308
}
313309
ty::ty_vec(_, ty::vstore_uniq) | ty::ty_str(ty::vstore_uniq) |
@@ -552,7 +548,6 @@ pub fn declare_tydesc(ccx: &CrateContext, t: ty::t) -> @tydesc_info {
552548

553549
let has_header = match ty::get(t).sty {
554550
ty::ty_box(..) => true,
555-
ty::ty_uniq(..) => ty::type_contents(ccx.tcx, t).owns_managed(),
556551
_ => false
557552
};
558553

‎src/librustc/middle/trans/reflect.rs

Lines changed: 2 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -184,11 +184,7 @@ impl<'a> Reflector<'a> {
184184
ty::ty_vec(ref mt, vst) => {
185185
let (name, extra) = self.vstore_name_and_extra(t, vst);
186186
let extra = extra + self.c_mt(mt);
187-
if "uniq" == name && ty::type_contents(bcx.tcx(), t).owns_managed() {
188-
self.visit("evec_uniq_managed", extra)
189-
} else {
190-
self.visit(~"evec_" + name, extra)
191-
}
187+
self.visit(~"evec_" + name, extra)
192188
}
193189
// Should remove mt from box and uniq.
194190
ty::ty_box(typ) => {
@@ -203,11 +199,7 @@ impl<'a> Reflector<'a> {
203199
ty: typ,
204200
mutbl: ast::MutImmutable,
205201
});
206-
if ty::type_contents(bcx.tcx(), t).owns_managed() {
207-
self.visit("uniq_managed", extra)
208-
} else {
209-
self.visit("uniq", extra)
210-
}
202+
self.visit("uniq", extra)
211203
}
212204
ty::ty_ptr(ref mt) => {
213205
let extra = self.c_mt(mt);

‎src/librustc/middle/trans/tvec.rs

Lines changed: 10 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -64,7 +64,14 @@ pub fn get_alloc(bcx: &Block, vptr: ValueRef) -> ValueRef {
6464
}
6565

6666
pub fn get_bodyptr(bcx: &Block, vptr: ValueRef, t: ty::t) -> ValueRef {
67-
if ty::type_contents(bcx.tcx(), t).owns_managed() {
67+
let vt = vec_types(bcx, t);
68+
69+
let managed = match ty::get(vt.vec_ty).sty {
70+
ty::ty_str(ty::vstore_box) | ty::ty_vec(_, ty::vstore_box) => true,
71+
_ => false
72+
};
73+
74+
if managed {
6875
GEPi(bcx, vptr, [0u, abi::box_field_body])
6976
} else {
7077
vptr
@@ -106,7 +113,6 @@ pub fn alloc_raw<'a>(
106113
base::malloc_general_dyn(bcx, vecbodyty, heap, vecsize);
107114
Store(bcx, fill, GEPi(bcx, body, [0u, abi::vec_elt_fill]));
108115
Store(bcx, alloc, GEPi(bcx, body, [0u, abi::vec_elt_alloc]));
109-
base::maybe_set_managed_unique_rc(bcx, bx, heap);
110116
return rslt(bcx, bx);
111117
}
112118
}
@@ -117,7 +123,7 @@ pub fn alloc_uniq_raw<'a>(
117123
fill: ValueRef,
118124
alloc: ValueRef)
119125
-> Result<'a> {
120-
alloc_raw(bcx, unit_ty, fill, alloc, base::heap_for_unique(bcx, unit_ty))
126+
alloc_raw(bcx, unit_ty, fill, alloc, heap_exchange)
121127
}
122128

123129
pub fn alloc_vec<'a>(
@@ -350,7 +356,7 @@ pub fn trans_uniq_or_managed_vstore<'a>(
350356
}
351357
}
352358
heap_exchange_closure => fail!("vectors use exchange_alloc"),
353-
heap_managed | heap_managed_unique => {}
359+
heap_managed => {}
354360
}
355361

356362
let vt = vec_types_from_expr(bcx, vstore_expr);

‎src/librustc/middle/trans/type_.rs

Lines changed: 1 addition & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -269,10 +269,6 @@ impl Type {
269269
Type::smart_ptr(ctx, &Type::opaque())
270270
}
271271

272-
pub fn unique(ctx: &CrateContext, ty: &Type) -> Type {
273-
Type::smart_ptr(ctx, ty)
274-
}
275-
276272
pub fn opaque_cbox_ptr(cx: &CrateContext) -> Type {
277273
Type::opaque_box(cx).ptr_to()
278274
}
@@ -281,7 +277,7 @@ impl Type {
281277
let tydesc_ptr = ctx.tydesc_type.ptr_to();
282278
let box_ty = match store {
283279
ty::BoxTraitStore => Type::opaque_box(ctx),
284-
ty::UniqTraitStore => Type::unique(ctx, &Type::i8()),
280+
ty::UniqTraitStore => Type::i8(),
285281
ty::RegionTraitStore(..) => Type::i8()
286282
};
287283
Type::struct_([tydesc_ptr, box_ty.ptr_to()], false)

‎src/librustc/middle/trans/type_of.rs

Lines changed: 2 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -245,21 +245,11 @@ pub fn type_of(cx: &CrateContext, t: ty::t) -> Type {
245245
Type::smart_ptr(cx, &ty).ptr_to()
246246
}
247247
ty::ty_uniq(typ) => {
248-
let ty = type_of(cx, typ);
249-
if ty::type_contents(cx.tcx, typ).owns_managed() {
250-
Type::unique(cx, &ty).ptr_to()
251-
} else {
252-
ty.ptr_to()
253-
}
248+
type_of(cx, typ).ptr_to()
254249
}
255250
ty::ty_vec(ref mt, ty::vstore_uniq) => {
256251
let ty = type_of(cx, mt.ty);
257-
let ty = Type::vec(cx.sess.targ_cfg.arch, &ty);
258-
if ty::type_contents(cx.tcx, mt.ty).owns_managed() {
259-
Type::unique(cx, &ty).ptr_to()
260-
} else {
261-
ty.ptr_to()
262-
}
252+
Type::vec(cx.sess.targ_cfg.arch, &ty).ptr_to()
263253
}
264254
ty::ty_unboxed_vec(ref mt) => {
265255
let ty = type_of(cx, mt.ty);

‎src/libstd/rc.rs

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -230,4 +230,12 @@ mod tests {
230230
drop(x);
231231
assert!(y.upgrade().is_none());
232232
}
233+
234+
#[test]
235+
fn gc_inside() {
236+
// see issue #11532
237+
use gc::Gc;
238+
let a = Rc::new(RefCell::new(Gc::new(1)));
239+
assert!(a.borrow().try_borrow_mut().is_some());
240+
}
233241
}

‎src/libstd/reflect.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -227,6 +227,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
227227
true
228228
}
229229

230+
#[cfg(stage0)]
230231
fn visit_uniq_managed(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
231232
self.align_to::<~u8>();
232233
if ! self.inner.visit_uniq_managed(mtbl, inner) { return false; }
@@ -275,6 +276,7 @@ impl<V:TyVisitor + MovePtr> TyVisitor for MovePtrAdaptor<V> {
275276
true
276277
}
277278

279+
#[cfg(stage0)]
278280
fn visit_evec_uniq_managed(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
279281
self.align_to::<~[@u8]>();
280282
if ! self.inner.visit_evec_uniq_managed(mtbl, inner) { return false; }

‎src/libstd/repr.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -310,6 +310,7 @@ impl<'a> TyVisitor for ReprVisitor<'a> {
310310
})
311311
}
312312

313+
#[cfg(stage0)]
313314
fn visit_uniq_managed(&mut self, _mtbl: uint, inner: *TyDesc) -> bool {
314315
self.writer.write(['~' as u8]);
315316
self.get::<&raw::Box<()>>(|this, b| {
@@ -358,6 +359,7 @@ impl<'a> TyVisitor for ReprVisitor<'a> {
358359
})
359360
}
360361

362+
#[cfg(stage0)]
361363
fn visit_evec_uniq_managed(&mut self, mtbl: uint, inner: *TyDesc) -> bool {
362364
self.get::<&raw::Box<raw::Vec<()>>>(|this, b| {
363365
this.writer.write(['~' as u8]);

‎src/libstd/unstable/intrinsics.rs

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -146,6 +146,7 @@ pub trait TyVisitor {
146146

147147
fn visit_box(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
148148
fn visit_uniq(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
149+
#[cfg(stage0)]
149150
fn visit_uniq_managed(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
150151
fn visit_ptr(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
151152
fn visit_rptr(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
@@ -154,6 +155,7 @@ pub trait TyVisitor {
154155
fn visit_unboxed_vec(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
155156
fn visit_evec_box(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
156157
fn visit_evec_uniq(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
158+
#[cfg(stage0)]
157159
fn visit_evec_uniq_managed(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
158160
fn visit_evec_slice(&mut self, mtbl: uint, inner: *TyDesc) -> bool;
159161
fn visit_evec_fixed(&mut self, n: uint, sz: uint, align: uint,

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