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Remove special case for Box<ZST> in trans #38574

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Merged
merged 1 commit into from
Dec 27, 2016
Merged

Remove special case for Box<ZST> in trans #38574

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1 change: 1 addition & 0 deletions src/liballoc/heap.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,7 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
}

#[cfg(not(test))]
#[cfg(stage0)]
#[lang = "exchange_free"]
#[inline]
unsafe fn exchange_free(ptr: *mut u8, old_size: usize, align: usize) {
Expand Down
1 change: 0 additions & 1 deletion src/librustc/middle/lang_items.rs
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Expand Up @@ -328,7 +328,6 @@ language_item_table! {
PanicFmtLangItem, "panic_fmt", panic_fmt;

ExchangeMallocFnLangItem, "exchange_malloc", exchange_malloc_fn;
ExchangeFreeFnLangItem, "exchange_free", exchange_free_fn;
BoxFreeFnLangItem, "box_free", box_free_fn;
StrDupUniqFnLangItem, "strdup_uniq", strdup_uniq_fn;

Expand Down
28 changes: 12 additions & 16 deletions src/librustc_trans/collector.rs
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Expand Up @@ -193,9 +193,9 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;

use rustc::hir::map as hir_map;
use rustc::hir::def_id::DefId;
use rustc::middle::lang_items::{ExchangeFreeFnLangItem, ExchangeMallocFnLangItem};
use rustc::middle::lang_items::{BoxFreeFnLangItem, ExchangeMallocFnLangItem};
use rustc::traits;
use rustc::ty::subst::{Substs, Subst};
use rustc::ty::subst::{Kind, Substs, Subst};
use rustc::ty::{self, TypeFoldable, TyCtxt};
use rustc::ty::adjustment::CustomCoerceUnsized;
use rustc::mir::{self, Location};
Expand All @@ -215,6 +215,8 @@ use util::nodemap::{FxHashSet, FxHashMap, DefIdMap};

use trans_item::{TransItem, DefPathBasedNames};

use std::iter;

#[derive(PartialEq, Eq, Hash, Clone, Copy, Debug)]
pub enum TransItemCollectionMode {
Eager,
Expand Down Expand Up @@ -723,23 +725,17 @@ fn find_drop_glue_neighbors<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>,

debug!("find_drop_glue_neighbors: {}", type_to_string(scx.tcx(), ty));

// Make sure the exchange_free_fn() lang-item gets translated if
// there is a boxed value.
if let ty::TyBox(_) = ty.sty {
let exchange_free_fn_def_id = scx.tcx()
.lang_items
.require(ExchangeFreeFnLangItem)
.unwrap_or_else(|e| scx.sess().fatal(&e));

assert!(can_have_local_instance(scx.tcx(), exchange_free_fn_def_id));
let fn_substs = scx.empty_substs_for_def_id(exchange_free_fn_def_id);
let exchange_free_fn_trans_item =
// Make sure the BoxFreeFn lang-item gets translated if there is a boxed value.
if let ty::TyBox(content_type) = ty.sty {
let def_id = scx.tcx().require_lang_item(BoxFreeFnLangItem);
assert!(can_have_local_instance(scx.tcx(), def_id));
let box_free_fn_trans_item =
create_fn_trans_item(scx,
exchange_free_fn_def_id,
fn_substs,
def_id,
scx.tcx().mk_substs(iter::once(Kind::from(content_type))),
scx.tcx().intern_substs(&[]));

output.push(exchange_free_fn_trans_item);
output.push(box_free_fn_trans_item);
}

// If the type implements Drop, also add a translation item for the
Expand Down
66 changes: 19 additions & 47 deletions src/librustc_trans/glue.rs
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Expand Up @@ -13,13 +13,15 @@
// Code relating to drop glue.

use std;
use std::iter;

use llvm;
use llvm::{ValueRef, get_param};
use middle::lang_items::ExchangeFreeFnLangItem;
use middle::lang_items::BoxFreeFnLangItem;
use rustc::ty::subst::{Substs};
use rustc::traits;
use rustc::ty::{self, AdtKind, Ty, TypeFoldable};
use rustc::ty::subst::Kind;
use adt::{self, MaybeSizedValue};
use base::*;
use callee::Callee;
Expand All @@ -36,38 +38,22 @@ use cleanup::CleanupScope;

use syntax_pos::DUMMY_SP;

pub fn trans_exchange_free_dyn<'a, 'tcx>(
pub fn trans_exchange_free_ty<'a, 'tcx>(
bcx: &BlockAndBuilder<'a, 'tcx>,
v: ValueRef,
size: ValueRef,
align: ValueRef
ptr: MaybeSizedValue,
content_ty: Ty<'tcx>
) {
let def_id = langcall(bcx.tcx(), None, "", ExchangeFreeFnLangItem);
let args = [bcx.pointercast(v, Type::i8p(bcx.ccx)), size, align];
let callee = Callee::def(bcx.ccx, def_id, bcx.tcx().intern_substs(&[]));
let def_id = langcall(bcx.tcx(), None, "", BoxFreeFnLangItem);
let substs = bcx.tcx().mk_substs(iter::once(Kind::from(content_ty)));
let callee = Callee::def(bcx.ccx, def_id, substs);

let ccx = bcx.ccx;
let fn_ty = callee.direct_fn_type(ccx, &[]);
let fn_ty = callee.direct_fn_type(bcx.ccx, &[]);

let llret = bcx.call(callee.reify(ccx), &args[..], None);
let llret = bcx.call(callee.reify(bcx.ccx),
&[ptr.value, ptr.meta][..1 + ptr.has_meta() as usize], None);
fn_ty.apply_attrs_callsite(llret);
}

pub fn trans_exchange_free_ty<'a, 'tcx>(
bcx: &BlockAndBuilder<'a, 'tcx>, ptr: ValueRef, content_ty: Ty<'tcx>
) {
assert!(bcx.ccx.shared().type_is_sized(content_ty));
let sizing_type = sizing_type_of(bcx.ccx, content_ty);
let content_size = llsize_of_alloc(bcx.ccx, sizing_type);

// `Box<ZeroSizeType>` does not allocate.
if content_size != 0 {
let content_align = align_of(bcx.ccx, content_ty);
let ccx = bcx.ccx;
trans_exchange_free_dyn(bcx, ptr, C_uint(ccx, content_size), C_uint(ccx, content_align));
}
}

pub fn get_drop_glue_type<'a, 'tcx>(scx: &SharedCrateContext<'a, 'tcx>, t: Ty<'tcx>) -> Ty<'tcx> {
assert!(t.is_normalized_for_trans());

Expand Down Expand Up @@ -224,30 +210,16 @@ pub fn implement_drop_glue<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, g: DropGlueKi
// special. It may move to library and have Drop impl. As
// a safe-guard, assert TyBox not used with TyContents.
assert!(!skip_dtor);
if !bcx.ccx.shared().type_is_sized(content_ty) {
let ptr = if !bcx.ccx.shared().type_is_sized(content_ty) {
let llbox = bcx.load(get_dataptr(&bcx, ptr.value));
let info = bcx.load(get_meta(&bcx, ptr.value));
drop_ty(&bcx, MaybeSizedValue::unsized_(llbox, info), content_ty);
let (llsize, llalign) = size_and_align_of_dst(&bcx, content_ty, info);

// `Box<ZeroSizeType>` does not allocate.
let needs_free = bcx.icmp(llvm::IntNE, llsize, C_uint(bcx.ccx, 0u64));
if const_to_opt_uint(needs_free) == Some(0) {
bcx
} else {
let next_cx = bcx.fcx().build_new_block("next");
let cond_cx = bcx.fcx().build_new_block("cond");
bcx.cond_br(needs_free, cond_cx.llbb(), next_cx.llbb());
trans_exchange_free_dyn(&cond_cx, llbox, llsize, llalign);
cond_cx.br(next_cx.llbb());
next_cx
}
MaybeSizedValue::unsized_(llbox, info)
} else {
let llbox = bcx.load(ptr.value);
drop_ty(&bcx, MaybeSizedValue::sized(llbox), content_ty);
trans_exchange_free_ty(&bcx, llbox, content_ty);
bcx
}
MaybeSizedValue::sized(bcx.load(ptr.value))
};
drop_ty(&bcx, ptr, content_ty);
trans_exchange_free_ty(&bcx, ptr, content_ty);
bcx
}
ty::TyDynamic(..) => {
// No support in vtable for distinguishing destroying with
Expand Down