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librustc: Implement a Pod kind for types that can be memcpy'd. #10924

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merged 4 commits into from
Dec 17, 2013
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librustc: Implement a Pod kind for types that can be memcpy'd. #10924

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caf34b4
librustc: Implement a `Pod` kind for types that can be `memcpy`'d.
pcwalton Dec 11, 2013
e7fbc1f
libstd: Implement the new `Cell`.
pcwalton Dec 11, 2013
36990df
test: Add a test that POD types can be implicitly copied.
pcwalton Dec 12, 2013
8657017
doc: Update the documentation to describe the `Pod` trait.
pcwalton Dec 15, 2013
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6 changes: 6 additions & 0 deletions doc/rust.md
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Expand Up @@ -3329,6 +3329,12 @@ The kinds are:
This kind includes scalars, owning pointers, owned closures, and
structural types containing only other owned types.
All `Send` types are `'static`.
`Pod`
: Types of this kind consist of "Plain Old Data"
which can be copied by simply moving bits.
All values of this kind can be implicitly copied.
This kind includes scalars and immutable references,
as well as structural types containing other `Pod` types.
`'static`
: Types of this kind do not contain any borrowed pointers;
this can be a useful guarantee for code
Expand Down
1 change: 1 addition & 0 deletions src/librustc/metadata/tyencode.rs
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Expand Up @@ -395,6 +395,7 @@ fn enc_bounds(w: @mut MemWriter, cx: @ctxt, bs: &ty::ParamBounds) {
ty::BoundFreeze => mywrite!(w, "K"),
ty::BoundStatic => mywrite!(w, "O"),
ty::BoundSized => mywrite!(w, "Z"),
ty::BoundPod => mywrite!(w, "P"),
}
}

Expand Down
100 changes: 52 additions & 48 deletions src/librustc/middle/lang_items.rs
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Expand Up @@ -23,7 +23,7 @@
use driver::session::Session;
use metadata::csearch::each_lang_item;
use metadata::cstore::iter_crate_data;
use middle::ty::{BuiltinBound, BoundFreeze, BoundSend, BoundSized};
use middle::ty::{BuiltinBound, BoundFreeze, BoundPod, BoundSend, BoundSized};
use syntax::ast;
use syntax::ast_util::local_def;
use syntax::attr::AttrMetaMethods;
Expand Down Expand Up @@ -83,6 +83,8 @@ impl LanguageItems {
Some(BoundSend)
} else if Some(id) == self.sized_trait() {
Some(BoundSized)
} else if Some(id) == self.pod_trait() {
Some(BoundPod)
} else {
None
}
Expand Down Expand Up @@ -206,56 +208,58 @@ pub fn collect_language_items(crate: &ast::Crate,
}

lets_do_this! {
There are 41 lang items.
There are 42 lang items.

// ID, Variant name, Name, Method name;
0, FreezeTraitLangItem, "freeze", freeze_trait;
1, SendTraitLangItem, "send", send_trait;
2, SizedTraitLangItem, "sized", sized_trait;

3, DropTraitLangItem, "drop", drop_trait;

4, AddTraitLangItem, "add", add_trait;
5, SubTraitLangItem, "sub", sub_trait;
6, MulTraitLangItem, "mul", mul_trait;
7, DivTraitLangItem, "div", div_trait;
8, RemTraitLangItem, "rem", rem_trait;
9, NegTraitLangItem, "neg", neg_trait;
10, NotTraitLangItem, "not", not_trait;
11, BitXorTraitLangItem, "bitxor", bitxor_trait;
12, BitAndTraitLangItem, "bitand", bitand_trait;
13, BitOrTraitLangItem, "bitor", bitor_trait;
14, ShlTraitLangItem, "shl", shl_trait;
15, ShrTraitLangItem, "shr", shr_trait;
16, IndexTraitLangItem, "index", index_trait;

17, EqTraitLangItem, "eq", eq_trait;
18, OrdTraitLangItem, "ord", ord_trait;

19, StrEqFnLangItem, "str_eq", str_eq_fn;
20, UniqStrEqFnLangItem, "uniq_str_eq", uniq_str_eq_fn;
21, FailFnLangItem, "fail_", fail_fn;
22, FailBoundsCheckFnLangItem, "fail_bounds_check", fail_bounds_check_fn;
23, ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn;
24, ClosureExchangeMallocFnLangItem, "closure_exchange_malloc", closure_exchange_malloc_fn;
25, ExchangeFreeFnLangItem, "exchange_free", exchange_free_fn;
26, MallocFnLangItem, "malloc", malloc_fn;
27, FreeFnLangItem, "free", free_fn;
28, BorrowAsImmFnLangItem, "borrow_as_imm", borrow_as_imm_fn;
29, BorrowAsMutFnLangItem, "borrow_as_mut", borrow_as_mut_fn;
30, ReturnToMutFnLangItem, "return_to_mut", return_to_mut_fn;
31, CheckNotBorrowedFnLangItem, "check_not_borrowed", check_not_borrowed_fn;
32, StrDupUniqFnLangItem, "strdup_uniq", strdup_uniq_fn;
33, RecordBorrowFnLangItem, "record_borrow", record_borrow_fn;
34, UnrecordBorrowFnLangItem, "unrecord_borrow", unrecord_borrow_fn;

35, StartFnLangItem, "start", start_fn;

36, TyDescStructLangItem, "ty_desc", ty_desc;
37, TyVisitorTraitLangItem, "ty_visitor", ty_visitor;
38, OpaqueStructLangItem, "opaque", opaque;

39, EventLoopFactoryLangItem, "event_loop_factory", event_loop_factory;

40, TypeIdLangItem, "type_id", type_id;
3, PodTraitLangItem, "pod", pod_trait;

4, DropTraitLangItem, "drop", drop_trait;

5, AddTraitLangItem, "add", add_trait;
6, SubTraitLangItem, "sub", sub_trait;
7, MulTraitLangItem, "mul", mul_trait;
8, DivTraitLangItem, "div", div_trait;
9, RemTraitLangItem, "rem", rem_trait;
10, NegTraitLangItem, "neg", neg_trait;
11, NotTraitLangItem, "not", not_trait;
12, BitXorTraitLangItem, "bitxor", bitxor_trait;
13, BitAndTraitLangItem, "bitand", bitand_trait;
14, BitOrTraitLangItem, "bitor", bitor_trait;
15, ShlTraitLangItem, "shl", shl_trait;
16, ShrTraitLangItem, "shr", shr_trait;
17, IndexTraitLangItem, "index", index_trait;

18, EqTraitLangItem, "eq", eq_trait;
19, OrdTraitLangItem, "ord", ord_trait;

20, StrEqFnLangItem, "str_eq", str_eq_fn;
21, UniqStrEqFnLangItem, "uniq_str_eq", uniq_str_eq_fn;
22, FailFnLangItem, "fail_", fail_fn;
23, FailBoundsCheckFnLangItem, "fail_bounds_check", fail_bounds_check_fn;
24, ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn;
25, ClosureExchangeMallocFnLangItem, "closure_exchange_malloc", closure_exchange_malloc_fn;
26, ExchangeFreeFnLangItem, "exchange_free", exchange_free_fn;
27, MallocFnLangItem, "malloc", malloc_fn;
28, FreeFnLangItem, "free", free_fn;
29, BorrowAsImmFnLangItem, "borrow_as_imm", borrow_as_imm_fn;
30, BorrowAsMutFnLangItem, "borrow_as_mut", borrow_as_mut_fn;
31, ReturnToMutFnLangItem, "return_to_mut", return_to_mut_fn;
32, CheckNotBorrowedFnLangItem, "check_not_borrowed", check_not_borrowed_fn;
33, StrDupUniqFnLangItem, "strdup_uniq", strdup_uniq_fn;
34, RecordBorrowFnLangItem, "record_borrow", record_borrow_fn;
35, UnrecordBorrowFnLangItem, "unrecord_borrow", unrecord_borrow_fn;

36, StartFnLangItem, "start", start_fn;

37, TyDescStructLangItem, "ty_desc", ty_desc;
38, TyVisitorTraitLangItem, "ty_visitor", ty_visitor;
39, OpaqueStructLangItem, "opaque", opaque;

40, EventLoopFactoryLangItem, "event_loop_factory", event_loop_factory;

41, TypeIdLangItem, "type_id", type_id;
}

45 changes: 36 additions & 9 deletions src/librustc/middle/ty.rs
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Expand Up @@ -737,6 +737,7 @@ pub enum BuiltinBound {
BoundSend,
BoundFreeze,
BoundSized,
BoundPod,
}

pub fn EmptyBuiltinBounds() -> BuiltinBounds {
Expand Down Expand Up @@ -1805,6 +1806,9 @@ def_type_content_sets!(
// Things that prevent values from being considered sized
Nonsized = 0b0000__00000000__0001,

// Things that make values considered not POD (same as `Moves`)
Nonpod = 0b0000__00001111__0000,

// Bits to set when a managed value is encountered
//
// [1] Do not set the bits TC::OwnsManaged or
Expand All @@ -1828,6 +1832,7 @@ impl TypeContents {
BoundFreeze => self.is_freezable(cx),
BoundSend => self.is_sendable(cx),
BoundSized => self.is_sized(cx),
BoundPod => self.is_pod(cx),
}
}

Expand Down Expand Up @@ -1859,6 +1864,10 @@ impl TypeContents {
!self.intersects(TC::Nonsized)
}

pub fn is_pod(&self, _: ctxt) -> bool {
!self.intersects(TC::Nonpod)
}

pub fn moves_by_default(&self, _: ctxt) -> bool {
self.intersects(TC::Moves)
}
Expand All @@ -1876,15 +1885,32 @@ impl TypeContents {
*self & (TC::OwnsAll | TC::ReachesAll))
}

pub fn other_pointer(&self, bits: TypeContents) -> TypeContents {
pub fn reference(&self, bits: TypeContents) -> TypeContents {
/*!
* Includes only those bits that still apply
* when indirected through a non-owning pointer (`&`, `@`)
* when indirected through a reference (`&`)
*/
bits | (
*self & TC::ReachesAll)
}

pub fn managed_pointer(&self) -> TypeContents {
/*!
* Includes only those bits that still apply
* when indirected through a managed pointer (`@`)
*/
TC::Managed | (
*self & TC::ReachesAll)
}

pub fn unsafe_pointer(&self) -> TypeContents {
/*!
* Includes only those bits that still apply
* when indirected through an unsafe pointer (`*`)
*/
*self & TC::ReachesAll
}

pub fn union<T>(v: &[T], f: |&T| -> TypeContents) -> TypeContents {
v.iter().fold(TC::None, |tc, t| tc | f(t))
}
Expand Down Expand Up @@ -1994,19 +2020,19 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
}

ty_box(mt) => {
tc_mt(cx, mt, cache).other_pointer(TC::Managed)
tc_mt(cx, mt, cache).managed_pointer()
}

ty_trait(_, _, store, mutbl, bounds) => {
object_contents(cx, store, mutbl, bounds)
}

ty_ptr(ref mt) => {
tc_ty(cx, mt.ty, cache).other_pointer(TC::None)
tc_ty(cx, mt.ty, cache).unsafe_pointer()
}

ty_rptr(r, ref mt) => {
tc_ty(cx, mt.ty, cache).other_pointer(
tc_ty(cx, mt.ty, cache).reference(
borrowed_contents(r, mt.mutbl))
}

Expand All @@ -2019,11 +2045,11 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
}

ty_evec(mt, vstore_box) => {
tc_mt(cx, mt, cache).other_pointer(TC::Managed)
tc_mt(cx, mt, cache).managed_pointer()
}

ty_evec(ref mt, vstore_slice(r)) => {
tc_ty(cx, mt.ty, cache).other_pointer(
tc_ty(cx, mt.ty, cache).reference(
borrowed_contents(r, mt.mutbl))
}

Expand Down Expand Up @@ -2193,10 +2219,10 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
contents.owned_pointer()
}
BoxTraitStore => {
contents.other_pointer(TC::Managed)
contents.managed_pointer()
}
RegionTraitStore(r) => {
contents.other_pointer(borrowed_contents(r, mutbl))
contents.reference(borrowed_contents(r, mutbl))
}
}
}
Expand All @@ -2213,6 +2239,7 @@ pub fn type_contents(cx: ctxt, ty: t) -> TypeContents {
BoundSend => TC::Nonsendable,
BoundFreeze => TC::Nonfreezable,
BoundSized => TC::Nonsized,
BoundPod => TC::Nonpod,
};
});
return tc;
Expand Down
2 changes: 2 additions & 0 deletions src/librustc/util/ppaux.rs
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Expand Up @@ -639,6 +639,7 @@ impl Repr for ty::ParamBounds {
ty::BoundSend => ~"Send",
ty::BoundFreeze => ~"Freeze",
ty::BoundSized => ~"Sized",
ty::BoundPod => ~"Pod",
});
}
for t in self.trait_bounds.iter() {
Expand Down Expand Up @@ -926,6 +927,7 @@ impl UserString for ty::BuiltinBound {
ty::BoundSend => ~"Send",
ty::BoundFreeze => ~"Freeze",
ty::BoundSized => ~"Sized",
ty::BoundPod => ~"Pod",
}
}
}
Expand Down
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