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Avoid redundant work for drop-glue translation items in trans::collector
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@michaelwoerister
michaelwoerister committed Jan 26, 2016
1 parent 9e96980 commit 4d074b8
Showing 1 changed file with 109 additions and 135 deletions.
244 changes: 109 additions & 135 deletions src/librustc_trans/trans/collector.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -350,14 +350,14 @@ fn collect_items_rec<'a, 'tcx: 'a>(ccx: &CrateContext<'a, 'tcx>,
let recursion_depth_reset;

match starting_point {
TransItem::DropGlue(_) |
TransItem::DropGlue(t) => {
find_drop_glue_neighbors(ccx, t, &mut neighbors);
recursion_depth_reset = None;
}
TransItem::Static(_) => {
recursion_depth_reset = None;
}
TransItem::Fn {
def_id,
substs: ref param_substs
} => {
TransItem::Fn { def_id, substs: ref param_substs } => {
// Keep track of the monomorphization recursion depth
recursion_depth_reset = Some(check_recursion_limit(ccx,
def_id,
Expand Down Expand Up @@ -531,11 +531,8 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirNeighborCollector<'a, 'tcx> {
self.param_substs,
&ty);
let ty = self.ccx.tcx().erase_regions(&ty);

create_drop_glue_trans_items(self.ccx,
ty,
self.param_substs,
&mut self.output);
let ty = glue::get_drop_glue_type(self.ccx, ty);
self.output.push(TransItem::DropGlue(ty));
}

self.super_lvalue(lvalue, context);
Expand Down Expand Up @@ -636,145 +633,124 @@ fn can_have_local_instance<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
def_id.is_local() || ccx.sess().cstore.is_item_mir_available(def_id)
}

fn create_drop_glue_trans_items<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
mono_ty: ty::Ty<'tcx>,
param_substs: &'tcx Substs<'tcx>,
output: &mut Vec<TransItem<'tcx>>)
fn find_drop_glue_neighbors<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
ty: ty::Ty<'tcx>,
output: &mut Vec<TransItem<'tcx>>)
{
visit_types_of_owned_components(ccx,
mono_ty,
&mut FnvHashSet(),
&mut |ty| {
debug!("create_drop_glue_trans_items: {}", type_to_string(ccx, ty));
// Add a translation item for the drop glue, if even this type does not
// need to be dropped (in which case it has been mapped to i8)
output.push(TransItem::DropGlue(ty));

if glue::type_needs_drop(ccx.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 = ccx.tcx()
.lang_items
.require(ExchangeFreeFnLangItem)
.expect("Could not find ExchangeFreeFnLangItem");

assert!(can_have_local_instance(ccx, exchange_free_fn_def_id));
let exchange_free_fn_trans_item =
create_fn_trans_item(ccx,
exchange_free_fn_def_id,
&Substs::trans_empty(),
param_substs);

output.push(exchange_free_fn_trans_item);
}

// If the type implements Drop, also add a translation item for the
// monomorphized Drop::drop() implementation.
let destructor_did = match ty.sty {
ty::TyStruct(def, _) |
ty::TyEnum(def, _) => def.destructor(),
_ => None
};

if let Some(destructor_did) = destructor_did {
use rustc::middle::ty::ToPolyTraitRef;
debug!("find_drop_glue_neighbors: {}", type_to_string(ccx, 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 = ccx.tcx()
.lang_items
.require(ExchangeFreeFnLangItem)
.expect("Could not find ExchangeFreeFnLangItem");

assert!(can_have_local_instance(ccx, exchange_free_fn_def_id));
let exchange_free_fn_trans_item =
create_fn_trans_item(ccx,
exchange_free_fn_def_id,
&Substs::trans_empty(),
&Substs::trans_empty());

output.push(exchange_free_fn_trans_item);
}

let drop_trait_def_id = ccx.tcx()
.lang_items
.drop_trait()
.unwrap();
// If the type implements Drop, also add a translation item for the
// monomorphized Drop::drop() implementation.
let destructor_did = match ty.sty {
ty::TyStruct(def, _) |
ty::TyEnum(def, _) => def.destructor(),
_ => None
};

let self_type_substs = ccx.tcx().mk_substs(
Substs::trans_empty().with_self_ty(ty));
if let Some(destructor_did) = destructor_did {
use rustc::middle::ty::ToPolyTraitRef;

let trait_ref = ty::TraitRef {
def_id: drop_trait_def_id,
substs: self_type_substs,
}.to_poly_trait_ref();
let drop_trait_def_id = ccx.tcx()
.lang_items
.drop_trait()
.unwrap();

let substs = match fulfill_obligation(ccx, DUMMY_SP, trait_ref) {
traits::VtableImpl(data) => data.substs,
_ => unreachable!()
};

if can_have_local_instance(ccx, destructor_did) {
let trans_item = create_fn_trans_item(ccx,
destructor_did,
ccx.tcx().mk_substs(substs),
param_substs);
output.push(trans_item);
}
}
let self_type_substs = ccx.tcx().mk_substs(
Substs::trans_empty().with_self_ty(ty));

true
} else {
false
}
});
let trait_ref = ty::TraitRef {
def_id: drop_trait_def_id,
substs: self_type_substs,
}.to_poly_trait_ref();

fn visit_types_of_owned_components<'a, 'tcx, F>(ccx: &CrateContext<'a, 'tcx>,
ty: ty::Ty<'tcx>,
visited: &mut FnvHashSet<ty::Ty<'tcx>>,
mut f: &mut F)
where F: FnMut(ty::Ty<'tcx>) -> bool
{
let ty = glue::get_drop_glue_type(ccx, ty);
let substs = match fulfill_obligation(ccx, DUMMY_SP, trait_ref) {
traits::VtableImpl(data) => data.substs,
_ => unreachable!()
};

if !visited.insert(ty) {
return;
if can_have_local_instance(ccx, destructor_did) {
let trans_item = create_fn_trans_item(ccx,
destructor_did,
ccx.tcx().mk_substs(substs),
&Substs::trans_empty());
output.push(trans_item);
}
}

if !f(ty) {
// Don't recurse further
return;
// Finally add the types of nested values
match ty.sty {
ty::TyBool |
ty::TyChar |
ty::TyInt(_) |
ty::TyUint(_) |
ty::TyStr |
ty::TyFloat(_) |
ty::TyRawPtr(_) |
ty::TyRef(..) |
ty::TyBareFn(..) |
ty::TySlice(_) |
ty::TyTrait(_) => {
/* nothing to do */
}

match ty.sty {
ty::TyBool |
ty::TyChar |
ty::TyInt(_) |
ty::TyUint(_) |
ty::TyStr |
ty::TyFloat(_) |
ty::TyRawPtr(_) |
ty::TyRef(..) |
ty::TyBareFn(..) |
ty::TySlice(_) |
ty::TyTrait(_) => {
/* nothing to do */
}
ty::TyStruct(ref adt_def, substs) |
ty::TyEnum(ref adt_def, substs) => {
for field in adt_def.all_fields() {
let field_type = monomorphize::apply_param_substs(ccx.tcx(),
substs,
&field.unsubst_ty());
visit_types_of_owned_components(ccx, field_type, visited, f);
ty::TyStruct(ref adt_def, substs) |
ty::TyEnum(ref adt_def, substs) => {
for field in adt_def.all_fields() {
let field_type = monomorphize::apply_param_substs(ccx.tcx(),
substs,
&field.unsubst_ty());
let field_type = glue::get_drop_glue_type(ccx, field_type);

if glue::type_needs_drop(ccx.tcx(), field_type) {
output.push(TransItem::DropGlue(field_type));
}
}
ty::TyClosure(_, ref substs) => {
for upvar_ty in &substs.upvar_tys {
visit_types_of_owned_components(ccx, upvar_ty, visited, f);
}
ty::TyClosure(_, ref substs) => {
for upvar_ty in &substs.upvar_tys {
let upvar_ty = glue::get_drop_glue_type(ccx, upvar_ty);
if glue::type_needs_drop(ccx.tcx(), upvar_ty) {
output.push(TransItem::DropGlue(upvar_ty));
}
}
ty::TyBox(inner_type) |
ty::TyArray(inner_type, _) => {
visit_types_of_owned_components(ccx, inner_type, visited, f);
}
ty::TyBox(inner_type) |
ty::TyArray(inner_type, _) => {
let inner_type = glue::get_drop_glue_type(ccx, inner_type);
if glue::type_needs_drop(ccx.tcx(), inner_type) {
output.push(TransItem::DropGlue(inner_type));
}
ty::TyTuple(ref args) => {
for arg in args {
visit_types_of_owned_components(ccx, arg, visited, f);
}
ty::TyTuple(ref args) => {
for arg in args {
let arg = glue::get_drop_glue_type(ccx, arg);
if glue::type_needs_drop(ccx.tcx(), arg) {
output.push(TransItem::DropGlue(arg));
}
}
ty::TyProjection(_) |
ty::TyParam(_) |
ty::TyInfer(_) |
ty::TyError => {
ccx.sess().bug("encountered unexpected type");
}
}
ty::TyProjection(_) |
ty::TyParam(_) |
ty::TyInfer(_) |
ty::TyError => {
ccx.sess().bug("encountered unexpected type");
}
}
}
Expand Down Expand Up @@ -1086,10 +1062,8 @@ impl<'b, 'a, 'v> hir_visit::Visitor<'v> for RootCollector<'b, 'a, 'v> {
self.ccx.tcx().map.local_def_id(item.id),
None));

create_drop_glue_trans_items(self.ccx,
ty,
self.trans_empty_substs,
self.output);
let ty = glue::get_drop_glue_type(self.ccx, ty);
self.output.push(TransItem::DropGlue(ty));
}
}
}
Expand Down

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