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auto merge of #14121 : luqmana/rust/option-ffi, r=alexcrichton

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This slightly adjusts the NullablePointer representation for some enums in the case where the non-nullable variant has a single field (the ptr field) to be just that, the pointer. This is in contrast to the current behaviour where we'd wrap that single pointer in a LLVM struct.

Fixes #11040 & #11303.
This commit is contained in:
bors 2014-05-18 01:16:27 -07:00
commit bf8648dbda
5 changed files with 158 additions and 59 deletions
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147
src/librustc/middle/trans/adt.rs
View file

@ -85,6 +85,18 @@ pub enum Repr {
* all start with a field for the discriminant.
*/
General(IntType, Vec<Struct>),
/**
* Two cases distinguished by a nullable pointer: the case with discriminant
* `nndiscr` must have single field which is known to be nonnull due to its type.
* The other case is known to be zero sized. Hence we represent the enum
* as simply a nullable pointer: if not null it indicates the `nndiscr` variant,
* otherwise it indicates the other case.
*/
RawNullablePointer {
pub nndiscr: Disr,
pub nnty: ty::t,
pub nullfields: Vec<ty::t>
},
/**
* Two cases distinguished by a nullable pointer: the case with discriminant
* `nndiscr` is represented by the struct `nonnull`, where the `ptrfield`th
@ -96,7 +108,7 @@ pub enum Repr {
* is represented such that `None` is a null pointer and `Some` is the
* identity function.
*/
NullablePointer {
StructWrappedNullablePointer {
pub nonnull: Struct,
pub nndiscr: Disr,
pub ptrfield: uint,
@ -200,17 +212,23 @@ fn represent_type_uncached(cx: &CrateContext, t: ty::t) -> Repr {
if cases.get(1 - discr).is_zerolen(cx) {
match cases.get(discr).find_ptr() {
Some(ptrfield) => {
return NullablePointer {
nndiscr: discr as u64,
nonnull: mk_struct(cx,
cases.get(discr)
.tys
.as_slice(),
false),
ptrfield: ptrfield,
nullfields: cases.get(1 - discr).tys
.clone()
}
let st = mk_struct(cx, cases.get(discr).tys.as_slice(),
false);
return if st.fields.len() == 1 {
RawNullablePointer {
nndiscr: discr as Disr,
nnty: *st.fields.get(0),
nullfields: cases.get(1 - discr).tys.clone()
}
} else {
StructWrappedNullablePointer {
nndiscr: discr as Disr,
nonnull: st,
ptrfield: ptrfield,
nullfields: cases.get(1 - discr).tys.clone()
}
};
}
None => { }
}
@ -413,8 +431,8 @@ pub fn incomplete_type_of(cx: &CrateContext, r: &Repr, name: &str) -> Type {
}
pub fn finish_type_of(cx: &CrateContext, r: &Repr, llty: &mut Type) {
match *r {
CEnum(..) | General(..) => { }
Univariant(ref st, _) | NullablePointer{ nonnull: ref st, .. } =>
CEnum(..) | General(..) | RawNullablePointer { .. } => { }
Univariant(ref st, _) | StructWrappedNullablePointer { nonnull: ref st, .. } =>
llty.set_struct_body(struct_llfields(cx, st, false).as_slice(),
st.packed)
}
@ -423,7 +441,8 @@ pub fn finish_type_of(cx: &CrateContext, r: &Repr, llty: &mut Type) {
fn generic_type_of(cx: &CrateContext, r: &Repr, name: Option<&str>, sizing: bool) -> Type {
match *r {
CEnum(ity, _, _) => ll_inttype(cx, ity),
Univariant(ref st, _) | NullablePointer{ nonnull: ref st, .. } => {
RawNullablePointer { nnty, .. } => type_of::sizing_type_of(cx, nnty),
Univariant(ref st, _) | StructWrappedNullablePointer { nonnull: ref st, .. } => {
match name {
None => {
Type::struct_(cx, struct_llfields(cx, st, sizing).as_slice(),
@ -495,12 +514,10 @@ fn struct_llfields(cx: &CrateContext, st: &Struct, sizing: bool) -> Vec<Type> {
pub fn trans_switch(bcx: &Block, r: &Repr, scrutinee: ValueRef)
-> (_match::branch_kind, Option<ValueRef>) {
match *r {
CEnum(..) | General(..) => {
CEnum(..) | General(..) |
RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
(_match::switch, Some(trans_get_discr(bcx, r, scrutinee, None)))
}
NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, .. } => {
(_match::switch, Some(nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee)))
}
Univariant(..) => {
(_match::single, None)
}
@ -528,8 +545,14 @@ pub fn trans_get_discr(bcx: &Block, r: &Repr, scrutinee: ValueRef, cast_to: Opti
val = C_u8(bcx.ccx(), 0);
signed = false;
}
NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, .. } => {
val = nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee);
RawNullablePointer { nndiscr, nnty, .. } => {
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
let llptrty = type_of::sizing_type_of(bcx.ccx(), nnty);
val = ICmp(bcx, cmp, Load(bcx, scrutinee), C_null(llptrty));
signed = false;
}
StructWrappedNullablePointer { nonnull: ref nonnull, nndiscr, ptrfield, .. } => {
val = struct_wrapped_nullable_bitdiscr(bcx, nonnull, nndiscr, ptrfield, scrutinee);
signed = false;
}
}
@ -539,10 +562,10 @@ pub fn trans_get_discr(bcx: &Block, r: &Repr, scrutinee: ValueRef, cast_to: Opti
}
}
fn nullable_bitdiscr(bcx: &Block, nonnull: &Struct, nndiscr: Disr, ptrfield: uint,
scrutinee: ValueRef) -> ValueRef {
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
fn struct_wrapped_nullable_bitdiscr(bcx: &Block, nonnull: &Struct, nndiscr: Disr, ptrfield: uint,
scrutinee: ValueRef) -> ValueRef {
let llptr = Load(bcx, GEPi(bcx, scrutinee, [0, ptrfield]));
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
let llptrty = type_of::type_of(bcx.ccx(), *nonnull.fields.get(ptrfield));
ICmp(bcx, cmp, llptr, C_null(llptrty))
}
@ -590,7 +613,8 @@ pub fn trans_case<'a>(bcx: &'a Block<'a>, r: &Repr, discr: Disr)
Univariant(..) => {
bcx.ccx().sess().bug("no cases for univariants or structs")
}
NullablePointer{ .. } => {
RawNullablePointer { .. } |
StructWrappedNullablePointer { .. } => {
assert!(discr == 0 || discr == 1);
_match::single_result(Result::new(bcx, C_i1(bcx.ccx(), discr != 0)))
}
@ -621,7 +645,13 @@ pub fn trans_start_init(bcx: &Block, r: &Repr, val: ValueRef, discr: Disr) {
Univariant(..) => {
assert_eq!(discr, 0);
}
NullablePointer{ nonnull: ref nonnull, nndiscr, ptrfield, .. } => {
RawNullablePointer { nndiscr, nnty, ..} => {
if discr != nndiscr {
let llptrty = type_of::sizing_type_of(bcx.ccx(), nnty);
Store(bcx, C_null(llptrty), val)
}
}
StructWrappedNullablePointer { nonnull: ref nonnull, nndiscr, ptrfield, .. } => {
if discr != nndiscr {
let llptrptr = GEPi(bcx, val, [0, ptrfield]);
let llptrty = type_of::type_of(bcx.ccx(),
@ -651,8 +681,11 @@ pub fn num_args(r: &Repr, discr: Disr) -> uint {
st.fields.len() - (if dtor { 1 } else { 0 })
}
General(_, ref cases) => cases.get(discr as uint).fields.len() - 1,
NullablePointer{ nonnull: ref nonnull, nndiscr,
nullfields: ref nullfields, .. } => {
RawNullablePointer { nndiscr, ref nullfields, .. } => {
if discr == nndiscr { 1 } else { nullfields.len() }
}
StructWrappedNullablePointer { nonnull: ref nonnull, nndiscr,
nullfields: ref nullfields, .. } => {
if discr == nndiscr { nonnull.fields.len() } else { nullfields.len() }
}
}
@ -675,19 +708,25 @@ pub fn trans_field_ptr(bcx: &Block, r: &Repr, val: ValueRef, discr: Disr,
General(_, ref cases) => {
struct_field_ptr(bcx, cases.get(discr as uint), val, ix + 1, true)
}
NullablePointer{ nonnull: ref nonnull, nullfields: ref nullfields,
nndiscr, .. } => {
if discr == nndiscr {
struct_field_ptr(bcx, nonnull, val, ix, false)
} else {
// The unit-like case might have a nonzero number of unit-like fields.
// (e.g., Result or Either with () as one side.)
let ty = type_of::type_of(bcx.ccx(), *nullfields.get(ix));
assert_eq!(machine::llsize_of_alloc(bcx.ccx(), ty), 0);
// The contents of memory at this pointer can't matter, but use
// the value that's "reasonable" in case of pointer comparison.
PointerCast(bcx, val, ty.ptr_to())
}
RawNullablePointer { nndiscr, ref nullfields, .. } |
StructWrappedNullablePointer { nndiscr, ref nullfields, .. } if discr != nndiscr => {
// The unit-like case might have a nonzero number of unit-like fields.
// (e.d., Result of Either with (), as one side.)
let ty = type_of::type_of(bcx.ccx(), *nullfields.get(ix));
assert_eq!(machine::llsize_of_alloc(bcx.ccx(), ty), 0);
// The contents of memory at this pointer can't matter, but use
// the value that's "reasonable" in case of pointer comparision.
PointerCast(bcx, val, ty.ptr_to())
}
RawNullablePointer { nndiscr, nnty, .. } => {
assert_eq!(ix, 0);
assert_eq!(discr, nndiscr);
let ty = type_of::type_of(bcx.ccx(), nnty);
PointerCast(bcx, val, ty.ptr_to())
}
StructWrappedNullablePointer { ref nonnull, nndiscr, .. } => {
assert_eq!(discr, nndiscr);
struct_field_ptr(bcx, nonnull, val, ix, false)
}
}
}
@ -759,7 +798,15 @@ pub fn trans_const(ccx: &CrateContext, r: &Repr, discr: Disr,
let contents = build_const_struct(ccx, st, vals);
C_struct(ccx, contents.as_slice(), st.packed)
}
NullablePointer{ nonnull: ref nonnull, nndiscr, .. } => {
RawNullablePointer { nndiscr, nnty, .. } => {
if discr == nndiscr {
assert_eq!(vals.len(), 1);
vals[0]
} else {
C_null(type_of::sizing_type_of(ccx, nnty))
}
}
StructWrappedNullablePointer { nonnull: ref nonnull, nndiscr, .. } => {
if discr == nndiscr {
C_struct(ccx, build_const_struct(ccx,
nonnull,
@ -867,7 +914,15 @@ pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef)
}
}
Univariant(..) => 0,
NullablePointer{ nndiscr, ptrfield, .. } => {
RawNullablePointer { nndiscr, .. } => {
if is_null(val) {
/* subtraction as uint is ok because nndiscr is either 0 or 1 */
(1 - nndiscr) as Disr
} else {
nndiscr
}
}
StructWrappedNullablePointer { nndiscr, ptrfield, .. } => {
if is_null(const_struct_field(ccx, val, ptrfield)) {
/* subtraction as uint is ok because nndiscr is either 0 or 1 */
(1 - nndiscr) as Disr
@ -891,7 +946,11 @@ pub fn const_get_field(ccx: &CrateContext, r: &Repr, val: ValueRef,
CEnum(..) => ccx.sess().bug("element access in C-like enum const"),
Univariant(..) => const_struct_field(ccx, val, ix),
General(..) => const_struct_field(ccx, val, ix + 1),
NullablePointer{ .. } => const_struct_field(ccx, val, ix)
RawNullablePointer { .. } => {
assert_eq!(ix, 0);
val
}
StructWrappedNullablePointer{ .. } => const_struct_field(ccx, val, ix)
}
}

5
src/librustc/middle/trans/debuginfo.rs
View file

@ -1675,7 +1675,10 @@ fn prepare_enum_metadata(cx: &CrateContext,
}),
}
}
adt::NullablePointer { nonnull: ref struct_def, nndiscr, .. } => {
adt::RawNullablePointer { nnty, .. } => {
FinalMetadata(type_metadata(cx, nnty, span))
}
adt::StructWrappedNullablePointer { nonnull: ref struct_def, nndiscr, .. } => {
let (metadata_stub,
variant_llvm_type,
member_description_factory) =

6
src/test/debuginfo/option-like-enum.rs
View file

@ -16,10 +16,10 @@
// gdb-command:finish
// gdb-command:print some
// gdb-check:$1 = {0x12345678}
// gdb-check:$1 = (u32 *) 0x12345678
// gdb-command:print none
// gdb-check:$2 = {0x0}
// gdb-check:$2 = (u32 *) 0x0
// gdb-command:print full
// gdb-check:$3 = {454545, 0x87654321, 9988}
@ -41,6 +41,8 @@
// contains a non-nullable pointer, then this value is used as the discriminator.
// The test cases in this file make sure that something readable is generated for
// this kind of types.
// If the non-empty variant contains a single non-nullable pointer than the whole
// item is represented as just a pointer and not wrapped in a struct.
// Unfortunately (for these test cases) the content of the non-discriminant fields
// in the null-case is not defined. So we just read the discriminator field in
// this case (by casting the value to a memory-equivalent struct).

24
src/test/debuginfo/recursive-struct.rs
View file

@ -20,53 +20,53 @@
// gdb-command:print stack_unique.value
// gdb-check:$1 = 0
// gdb-command:print stack_unique.next.val->value
// gdb-command:print stack_unique.next->value
// gdb-check:$2 = 1
// gdb-command:print unique_unique->value
// gdb-check:$3 = 2
// gdb-command:print unique_unique->next.val->value
// gdb-command:print unique_unique->next->value
// gdb-check:$4 = 3
// gdb-command:print box_unique->val.value
// gdb-check:$5 = 4
// gdb-command:print box_unique->val.next.val->value
// gdb-command:print box_unique->val.next->value
// gdb-check:$6 = 5
// gdb-command:print vec_unique[0].value
// gdb-check:$7 = 6.5
// gdb-command:print vec_unique[0].next.val->value
// gdb-command:print vec_unique[0].next->value
// gdb-check:$8 = 7.5
// gdb-command:print borrowed_unique->value
// gdb-check:$9 = 8.5
// gdb-command:print borrowed_unique->next.val->value
// gdb-command:print borrowed_unique->next->value
// gdb-check:$10 = 9.5
// MANAGED
// gdb-command:print stack_managed.value
// gdb-check:$11 = 10
// gdb-command:print stack_managed.next.val->val.value
// gdb-command:print stack_managed.next.val->value
// gdb-check:$12 = 11
// gdb-command:print unique_managed->value
// gdb-check:$13 = 12
// gdb-command:print unique_managed->next.val->val.value
// gdb-command:print unique_managed->next.val->value
// gdb-check:$14 = 13
// gdb-command:print box_managed->val.value
// gdb-command:print box_managed.val->value
// gdb-check:$15 = 14
// gdb-command:print box_managed->val.next.val->val.value
// gdb-command:print box_managed->val->next.val->value
// gdb-check:$16 = 15
// gdb-command:print vec_managed[0].value
// gdb-check:$17 = 16.5
// gdb-command:print vec_managed[0].next.val->val.value
// gdb-command:print vec_managed[0].next.val->value
// gdb-check:$18 = 17.5
// gdb-command:print borrowed_managed->value
// gdb-check:$19 = 18.5
// gdb-command:print borrowed_managed->next.val->val.value
// gdb-command:print borrowed_managed->next.val->value
// gdb-check:$20 = 19.5
// LONG CYCLE
@ -97,7 +97,7 @@
// gdb-command:print (*****long_cycle_w_anonymous_types).value
// gdb-check:$31 = 30
// gdb-command:print (*****((*****long_cycle_w_anonymous_types).next.val)).value
// gdb-command:print (*****((*****long_cycle_w_anonymous_types).next)).value
// gdb-check:$32 = 31
// gdb-command:continue

35
src/test/run-pass/nullable-pointer-ffi-compat.rs Normal file
View file

@ -0,0 +1,35 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// #11303, #11040:
// This would previously crash on i686 linux due to abi differences
// between returning an Option<T> and T, where T is a non nullable
// pointer.
// If we have an enum with two variants such that one is zero sized
// and the other contains a nonnullable pointer, we don't use a
// separate discriminant. Instead we use that pointer field to differentiate
// between the 2 cases.
// Also, if the variant with the nonnullable pointer has no other fields
// then we simply express the enum as just a pointer and not wrap it
// in a struct.
use std::mem;
#[inline(never)]
extern "C" fn foo<'a>(x: &'a int) -> Option<&'a int> { Some(x) }
static FOO: int = 0xDEADBEE;
pub fn main() {
unsafe {
let f: extern "C" fn<'a>(&'a int) -> &'a int = mem::transmute(foo);
assert_eq!(*f(&FOO), FOO);
}
}