| // Copyright 2012-2013 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. |
| |
| //! |
| // |
| // Code relating to drop glue. |
| |
| use std; |
| |
| use llvm; |
| use llvm::{ValueRef, get_param}; |
| use middle::lang_items::ExchangeFreeFnLangItem; |
| use rustc::ty::subst::{Substs}; |
| use rustc::traits; |
| use rustc::ty::{self, Ty, TyCtxt, TypeFoldable}; |
| use adt; |
| use adt::GetDtorType; // for tcx.dtor_type() |
| use base::*; |
| use build::*; |
| use callee::{Callee, ArgVals}; |
| use cleanup; |
| use cleanup::CleanupMethods; |
| use common::*; |
| use debuginfo::DebugLoc; |
| use expr; |
| use machine::*; |
| use monomorphize; |
| use trans_item::TransItem; |
| use type_of::{type_of, sizing_type_of, align_of}; |
| use type_::Type; |
| use value::Value; |
| |
| use arena::TypedArena; |
| use syntax_pos::DUMMY_SP; |
| |
| pub fn trans_exchange_free_dyn<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| v: ValueRef, |
| size: ValueRef, |
| align: ValueRef, |
| debug_loc: DebugLoc) |
| -> Block<'blk, 'tcx> { |
| let _icx = push_ctxt("trans_exchange_free"); |
| |
| let def_id = langcall(bcx.tcx(), None, "", ExchangeFreeFnLangItem); |
| let args = [PointerCast(bcx, v, Type::i8p(bcx.ccx())), size, align]; |
| Callee::def(bcx.ccx(), def_id, bcx.tcx().mk_substs(Substs::empty())) |
| .call(bcx, debug_loc, ArgVals(&args), None).bcx |
| } |
| |
| pub fn trans_exchange_free<'blk, 'tcx>(cx: Block<'blk, 'tcx>, |
| v: ValueRef, |
| size: u64, |
| align: u32, |
| debug_loc: DebugLoc) |
| -> Block<'blk, 'tcx> { |
| trans_exchange_free_dyn(cx, |
| v, |
| C_uint(cx.ccx(), size), |
| C_uint(cx.ccx(), align), |
| debug_loc) |
| } |
| |
| pub fn trans_exchange_free_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| ptr: ValueRef, |
| content_ty: Ty<'tcx>, |
| debug_loc: DebugLoc) |
| -> Block<'blk, 'tcx> { |
| assert!(type_is_sized(bcx.ccx().tcx(), 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); |
| trans_exchange_free(bcx, ptr, content_size, content_align, debug_loc) |
| } else { |
| bcx |
| } |
| } |
| |
| pub fn type_needs_drop<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| ty: Ty<'tcx>) -> bool { |
| tcx.type_needs_drop_given_env(ty, &tcx.empty_parameter_environment()) |
| } |
| |
| pub fn get_drop_glue_type<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, |
| t: Ty<'tcx>) -> Ty<'tcx> { |
| assert!(t.is_normalized_for_trans()); |
| |
| // Even if there is no dtor for t, there might be one deeper down and we |
| // might need to pass in the vtable ptr. |
| if !type_is_sized(tcx, t) { |
| return t; |
| } |
| |
| // FIXME (#22815): note that type_needs_drop conservatively |
| // approximates in some cases and may say a type expression |
| // requires drop glue when it actually does not. |
| // |
| // (In this case it is not clear whether any harm is done, i.e. |
| // erroneously returning `t` in some cases where we could have |
| // returned `tcx.types.i8` does not appear unsound. The impact on |
| // code quality is unknown at this time.) |
| |
| if !type_needs_drop(tcx, t) { |
| return tcx.types.i8; |
| } |
| match t.sty { |
| ty::TyBox(typ) if !type_needs_drop(tcx, typ) |
| && type_is_sized(tcx, typ) => { |
| tcx.normalizing_infer_ctxt(traits::ProjectionMode::Any).enter(|infcx| { |
| let layout = t.layout(&infcx).unwrap(); |
| if layout.size(&tcx.data_layout).bytes() == 0 { |
| // `Box<ZeroSizeType>` does not allocate. |
| tcx.types.i8 |
| } else { |
| t |
| } |
| }) |
| } |
| _ => t |
| } |
| } |
| |
| pub fn drop_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| v: ValueRef, |
| t: Ty<'tcx>, |
| debug_loc: DebugLoc) -> Block<'blk, 'tcx> { |
| drop_ty_core(bcx, v, t, debug_loc, false, None) |
| } |
| |
| pub fn drop_ty_core<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| v: ValueRef, |
| t: Ty<'tcx>, |
| debug_loc: DebugLoc, |
| skip_dtor: bool, |
| drop_hint: Option<cleanup::DropHintValue>) |
| -> Block<'blk, 'tcx> { |
| // NB: v is an *alias* of type t here, not a direct value. |
| debug!("drop_ty_core(t={:?}, skip_dtor={} drop_hint={:?})", t, skip_dtor, drop_hint); |
| let _icx = push_ctxt("drop_ty"); |
| let mut bcx = bcx; |
| if bcx.fcx.type_needs_drop(t) { |
| let ccx = bcx.ccx(); |
| let g = if skip_dtor { |
| DropGlueKind::TyContents(t) |
| } else { |
| DropGlueKind::Ty(t) |
| }; |
| let glue = get_drop_glue_core(ccx, g); |
| let glue_type = get_drop_glue_type(ccx.tcx(), t); |
| let ptr = if glue_type != t { |
| PointerCast(bcx, v, type_of(ccx, glue_type).ptr_to()) |
| } else { |
| v |
| }; |
| |
| match drop_hint { |
| Some(drop_hint) => { |
| let hint_val = load_ty(bcx, drop_hint.value(), bcx.tcx().types.u8); |
| let moved_val = |
| C_integral(Type::i8(bcx.ccx()), adt::DTOR_MOVED_HINT as u64, false); |
| let may_need_drop = |
| ICmp(bcx, llvm::IntNE, hint_val, moved_val, DebugLoc::None); |
| bcx = with_cond(bcx, may_need_drop, |cx| { |
| Call(cx, glue, &[ptr], debug_loc); |
| cx |
| }) |
| } |
| None => { |
| // No drop-hint ==> call standard drop glue |
| Call(bcx, glue, &[ptr], debug_loc); |
| } |
| } |
| } |
| bcx |
| } |
| |
| pub fn drop_ty_immediate<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| v: ValueRef, |
| t: Ty<'tcx>, |
| debug_loc: DebugLoc, |
| skip_dtor: bool) |
| -> Block<'blk, 'tcx> { |
| let _icx = push_ctxt("drop_ty_immediate"); |
| let vp = alloc_ty(bcx, t, ""); |
| call_lifetime_start(bcx, vp); |
| store_ty(bcx, v, vp, t); |
| let bcx = drop_ty_core(bcx, vp, t, debug_loc, skip_dtor, None); |
| call_lifetime_end(bcx, vp); |
| bcx |
| } |
| |
| pub fn get_drop_glue<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> ValueRef { |
| get_drop_glue_core(ccx, DropGlueKind::Ty(t)) |
| } |
| |
| #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
| pub enum DropGlueKind<'tcx> { |
| /// The normal path; runs the dtor, and then recurs on the contents |
| Ty(Ty<'tcx>), |
| /// Skips the dtor, if any, for ty; drops the contents directly. |
| /// Note that the dtor is only skipped at the most *shallow* |
| /// level, namely, an `impl Drop for Ty` itself. So, for example, |
| /// if Ty is Newtype(S) then only the Drop impl for Newtype itself |
| /// will be skipped, while the Drop impl for S, if any, will be |
| /// invoked. |
| TyContents(Ty<'tcx>), |
| } |
| |
| impl<'tcx> DropGlueKind<'tcx> { |
| pub fn ty(&self) -> Ty<'tcx> { |
| match *self { DropGlueKind::Ty(t) | DropGlueKind::TyContents(t) => t } |
| } |
| |
| pub fn map_ty<F>(&self, mut f: F) -> DropGlueKind<'tcx> where F: FnMut(Ty<'tcx>) -> Ty<'tcx> |
| { |
| match *self { |
| DropGlueKind::Ty(t) => DropGlueKind::Ty(f(t)), |
| DropGlueKind::TyContents(t) => DropGlueKind::TyContents(f(t)), |
| } |
| } |
| } |
| |
| fn get_drop_glue_core<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, |
| g: DropGlueKind<'tcx>) -> ValueRef { |
| let g = g.map_ty(|t| get_drop_glue_type(ccx.tcx(), t)); |
| match ccx.drop_glues().borrow().get(&g) { |
| Some(&(glue, _)) => return glue, |
| None => { |
| debug!("Could not find drop glue for {:?} -- {} -- {}. \ |
| Falling back to on-demand instantiation.", |
| g, |
| TransItem::DropGlue(g).to_raw_string(), |
| ccx.codegen_unit().name()); |
| |
| ccx.stats().n_fallback_instantiations.set(ccx.stats() |
| .n_fallback_instantiations |
| .get() + 1); |
| } |
| } |
| |
| // FIXME: #34151 |
| // Normally, getting here would indicate a bug in trans::collector, |
| // since it seems to have missed a translation item. When we are |
| // translating with non-MIR-based trans, however, the results of the |
| // collector are not entirely reliable since it bases its analysis |
| // on MIR. Thus, we'll instantiate the missing function on demand in |
| // this codegen unit, so that things keep working. |
| |
| TransItem::DropGlue(g).predefine(ccx, llvm::InternalLinkage); |
| TransItem::DropGlue(g).define(ccx); |
| |
| // Now that we made sure that the glue function is in ccx.drop_glues, |
| // give it another try |
| get_drop_glue_core(ccx, g) |
| } |
| |
| pub fn implement_drop_glue<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, |
| g: DropGlueKind<'tcx>) { |
| let tcx = ccx.tcx(); |
| assert_eq!(g.ty(), get_drop_glue_type(tcx, g.ty())); |
| let (llfn, fn_ty) = ccx.drop_glues().borrow().get(&g).unwrap().clone(); |
| |
| let (arena, fcx): (TypedArena<_>, FunctionContext); |
| arena = TypedArena::new(); |
| fcx = FunctionContext::new(ccx, llfn, fn_ty, None, &arena); |
| |
| let bcx = fcx.init(false, None); |
| |
| ccx.stats().n_glues_created.set(ccx.stats().n_glues_created.get() + 1); |
| // All glue functions take values passed *by alias*; this is a |
| // requirement since in many contexts glue is invoked indirectly and |
| // the caller has no idea if it's dealing with something that can be |
| // passed by value. |
| // |
| // llfn is expected be declared to take a parameter of the appropriate |
| // type, so we don't need to explicitly cast the function parameter. |
| |
| let bcx = make_drop_glue(bcx, get_param(llfn, 0), g); |
| fcx.finish(bcx, DebugLoc::None); |
| } |
| |
| |
| fn trans_struct_drop_flag<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>, |
| t: Ty<'tcx>, |
| struct_data: ValueRef) |
| -> Block<'blk, 'tcx> { |
| assert!(type_is_sized(bcx.tcx(), t), "Precondition: caller must ensure t is sized"); |
| |
| let repr = adt::represent_type(bcx.ccx(), t); |
| let drop_flag = unpack_datum!(bcx, adt::trans_drop_flag_ptr(bcx, &repr, struct_data)); |
| let loaded = load_ty(bcx, drop_flag.val, bcx.tcx().dtor_type()); |
| let drop_flag_llty = type_of(bcx.fcx.ccx, bcx.tcx().dtor_type()); |
| let init_val = C_integral(drop_flag_llty, adt::DTOR_NEEDED as u64, false); |
| |
| let bcx = if !bcx.ccx().check_drop_flag_for_sanity() { |
| bcx |
| } else { |
| let drop_flag_llty = type_of(bcx.fcx.ccx, bcx.tcx().dtor_type()); |
| let done_val = C_integral(drop_flag_llty, adt::DTOR_DONE as u64, false); |
| let not_init = ICmp(bcx, llvm::IntNE, loaded, init_val, DebugLoc::None); |
| let not_done = ICmp(bcx, llvm::IntNE, loaded, done_val, DebugLoc::None); |
| let drop_flag_neither_initialized_nor_cleared = |
| And(bcx, not_init, not_done, DebugLoc::None); |
| with_cond(bcx, drop_flag_neither_initialized_nor_cleared, |cx| { |
| let llfn = cx.ccx().get_intrinsic(&("llvm.debugtrap")); |
| Call(cx, llfn, &[], DebugLoc::None); |
| cx |
| }) |
| }; |
| |
| let drop_flag_dtor_needed = ICmp(bcx, llvm::IntEQ, loaded, init_val, DebugLoc::None); |
| with_cond(bcx, drop_flag_dtor_needed, |cx| { |
| trans_struct_drop(cx, t, struct_data) |
| }) |
| } |
| fn trans_struct_drop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, |
| t: Ty<'tcx>, |
| v0: ValueRef) |
| -> Block<'blk, 'tcx> |
| { |
| debug!("trans_struct_drop t: {}", t); |
| let tcx = bcx.tcx(); |
| let mut bcx = bcx; |
| |
| let def = t.ty_adt_def().unwrap(); |
| |
| // Be sure to put the contents into a scope so we can use an invoke |
| // instruction to call the user destructor but still call the field |
| // destructors if the user destructor panics. |
| // |
| // FIXME (#14875) panic-in-drop semantics might be unsupported; we |
| // might well consider changing below to more direct code. |
| let contents_scope = bcx.fcx.push_custom_cleanup_scope(); |
| |
| // Issue #23611: schedule cleanup of contents, re-inspecting the |
| // discriminant (if any) in case of variant swap in drop code. |
| bcx.fcx.schedule_drop_adt_contents(cleanup::CustomScope(contents_scope), v0, t); |
| |
| let (sized_args, unsized_args); |
| let args: &[ValueRef] = if type_is_sized(tcx, t) { |
| sized_args = [v0]; |
| &sized_args |
| } else { |
| unsized_args = [Load(bcx, expr::get_dataptr(bcx, v0)), Load(bcx, expr::get_meta(bcx, v0))]; |
| &unsized_args |
| }; |
| |
| let trait_ref = ty::Binder(ty::TraitRef { |
| def_id: tcx.lang_items.drop_trait().unwrap(), |
| substs: tcx.mk_substs(Substs::empty().with_self_ty(t)) |
| }); |
| let vtbl = match fulfill_obligation(bcx.ccx().shared(), DUMMY_SP, trait_ref) { |
| traits::VtableImpl(data) => data, |
| _ => bug!("dtor for {:?} is not an impl???", t) |
| }; |
| let dtor_did = def.destructor().unwrap(); |
| bcx = Callee::def(bcx.ccx(), dtor_did, vtbl.substs) |
| .call(bcx, DebugLoc::None, ArgVals(args), None).bcx; |
| |
| bcx.fcx.pop_and_trans_custom_cleanup_scope(bcx, contents_scope) |
| } |
| |
| pub fn size_and_align_of_dst<'blk, 'tcx>(bcx: &BlockAndBuilder<'blk, 'tcx>, |
| t: Ty<'tcx>, info: ValueRef) |
| -> (ValueRef, ValueRef) { |
| debug!("calculate size of DST: {}; with lost info: {:?}", |
| t, Value(info)); |
| if type_is_sized(bcx.tcx(), t) { |
| let sizing_type = sizing_type_of(bcx.ccx(), t); |
| let size = llsize_of_alloc(bcx.ccx(), sizing_type); |
| let align = align_of(bcx.ccx(), t); |
| debug!("size_and_align_of_dst t={} info={:?} size: {} align: {}", |
| t, Value(info), size, align); |
| let size = C_uint(bcx.ccx(), size); |
| let align = C_uint(bcx.ccx(), align); |
| return (size, align); |
| } |
| if bcx.is_unreachable() { |
| let llty = Type::int(bcx.ccx()); |
| return (C_undef(llty), C_undef(llty)); |
| } |
| match t.sty { |
| ty::TyStruct(def, substs) => { |
| let ccx = bcx.ccx(); |
| // First get the size of all statically known fields. |
| // Don't use type_of::sizing_type_of because that expects t to be sized. |
| assert!(!t.is_simd()); |
| let repr = adt::represent_type(ccx, t); |
| let sizing_type = adt::sizing_type_context_of(ccx, &repr, true); |
| debug!("DST {} sizing_type: {:?}", t, sizing_type); |
| let sized_size = llsize_of_alloc(ccx, sizing_type.prefix()); |
| let sized_align = llalign_of_min(ccx, sizing_type.prefix()); |
| debug!("DST {} statically sized prefix size: {} align: {}", |
| t, sized_size, sized_align); |
| let sized_size = C_uint(ccx, sized_size); |
| let sized_align = C_uint(ccx, sized_align); |
| |
| // Recurse to get the size of the dynamically sized field (must be |
| // the last field). |
| let last_field = def.struct_variant().fields.last().unwrap(); |
| let field_ty = monomorphize::field_ty(bcx.tcx(), substs, last_field); |
| let (unsized_size, unsized_align) = size_and_align_of_dst(bcx, field_ty, info); |
| |
| // FIXME (#26403, #27023): We should be adding padding |
| // to `sized_size` (to accommodate the `unsized_align` |
| // required of the unsized field that follows) before |
| // summing it with `sized_size`. (Note that since #26403 |
| // is unfixed, we do not yet add the necessary padding |
| // here. But this is where the add would go.) |
| |
| // Return the sum of sizes and max of aligns. |
| let mut size = bcx.add(sized_size, unsized_size); |
| |
| // Issue #27023: If there is a drop flag, *now* we add 1 |
| // to the size. (We can do this without adding any |
| // padding because drop flags do not have any alignment |
| // constraints.) |
| if sizing_type.needs_drop_flag() { |
| size = bcx.add(size, C_uint(bcx.ccx(), 1_u64)); |
| } |
| |
| // Choose max of two known alignments (combined value must |
| // be aligned according to more restrictive of the two). |
| let align = match (const_to_opt_uint(sized_align), const_to_opt_uint(unsized_align)) { |
| (Some(sized_align), Some(unsized_align)) => { |
| // If both alignments are constant, (the sized_align should always be), then |
| // pick the correct alignment statically. |
| C_uint(ccx, std::cmp::max(sized_align, unsized_align)) |
| } |
| _ => bcx.select(bcx.icmp(llvm::IntUGT, sized_align, unsized_align), |
| sized_align, |
| unsized_align) |
| }; |
| |
| // Issue #27023: must add any necessary padding to `size` |
| // (to make it a multiple of `align`) before returning it. |
| // |
| // Namely, the returned size should be, in C notation: |
| // |
| // `size + ((size & (align-1)) ? align : 0)` |
| // |
| // emulated via the semi-standard fast bit trick: |
| // |
| // `(size + (align-1)) & -align` |
| |
| let addend = bcx.sub(align, C_uint(bcx.ccx(), 1_u64)); |
| let size = bcx.and(bcx.add(size, addend), bcx.neg(align)); |
| |
| (size, align) |
| } |
| ty::TyTrait(..) => { |
| // info points to the vtable and the second entry in the vtable is the |
| // dynamic size of the object. |
| let info = bcx.pointercast(info, Type::int(bcx.ccx()).ptr_to()); |
| let size_ptr = bcx.gepi(info, &[1]); |
| let align_ptr = bcx.gepi(info, &[2]); |
| (bcx.load(size_ptr), bcx.load(align_ptr)) |
| } |
| ty::TySlice(_) | ty::TyStr => { |
| let unit_ty = t.sequence_element_type(bcx.tcx()); |
| // The info in this case is the length of the str, so the size is that |
| // times the unit size. |
| let llunit_ty = sizing_type_of(bcx.ccx(), unit_ty); |
| let unit_align = llalign_of_min(bcx.ccx(), llunit_ty); |
| let unit_size = llsize_of_alloc(bcx.ccx(), llunit_ty); |
| (bcx.mul(info, C_uint(bcx.ccx(), unit_size)), |
| C_uint(bcx.ccx(), unit_align)) |
| } |
| _ => bug!("Unexpected unsized type, found {}", t) |
| } |
| } |
| |
| fn make_drop_glue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, v0: ValueRef, g: DropGlueKind<'tcx>) |
| -> Block<'blk, 'tcx> { |
| let t = g.ty(); |
| |
| let skip_dtor = match g { DropGlueKind::Ty(_) => false, DropGlueKind::TyContents(_) => true }; |
| // NB: v0 is an *alias* of type t here, not a direct value. |
| let _icx = push_ctxt("make_drop_glue"); |
| |
| // Only drop the value when it ... well, we used to check for |
| // non-null, (and maybe we need to continue doing so), but we now |
| // must definitely check for special bit-patterns corresponding to |
| // the special dtor markings. |
| |
| let inttype = Type::int(bcx.ccx()); |
| let dropped_pattern = C_integral(inttype, adt::DTOR_DONE_U64, false); |
| |
| match t.sty { |
| ty::TyBox(content_ty) => { |
| // Support for TyBox is built-in and its drop glue is |
| // special. It may move to library and have Drop impl. As |
| // a safe-guard, assert TyBox not used with TyContents. |
| assert!(!skip_dtor); |
| if !type_is_sized(bcx.tcx(), content_ty) { |
| let llval = expr::get_dataptr(bcx, v0); |
| let llbox = Load(bcx, llval); |
| let llbox_as_usize = PtrToInt(bcx, llbox, Type::int(bcx.ccx())); |
| let drop_flag_not_dropped_already = |
| ICmp(bcx, llvm::IntNE, llbox_as_usize, dropped_pattern, DebugLoc::None); |
| with_cond(bcx, drop_flag_not_dropped_already, |bcx| { |
| let bcx = drop_ty(bcx, v0, content_ty, DebugLoc::None); |
| let info = expr::get_meta(bcx, v0); |
| let info = Load(bcx, info); |
| let (llsize, llalign) = |
| size_and_align_of_dst(&bcx.build(), content_ty, info); |
| |
| // `Box<ZeroSizeType>` does not allocate. |
| let needs_free = ICmp(bcx, |
| llvm::IntNE, |
| llsize, |
| C_uint(bcx.ccx(), 0u64), |
| DebugLoc::None); |
| with_cond(bcx, needs_free, |bcx| { |
| trans_exchange_free_dyn(bcx, llbox, llsize, llalign, DebugLoc::None) |
| }) |
| }) |
| } else { |
| let llval = v0; |
| let llbox = Load(bcx, llval); |
| let llbox_as_usize = PtrToInt(bcx, llbox, inttype); |
| let drop_flag_not_dropped_already = |
| ICmp(bcx, llvm::IntNE, llbox_as_usize, dropped_pattern, DebugLoc::None); |
| with_cond(bcx, drop_flag_not_dropped_already, |bcx| { |
| let bcx = drop_ty(bcx, llbox, content_ty, DebugLoc::None); |
| trans_exchange_free_ty(bcx, llbox, content_ty, DebugLoc::None) |
| }) |
| } |
| } |
| ty::TyStruct(def, _) | ty::TyEnum(def, _) => { |
| match (def.dtor_kind(), skip_dtor) { |
| (ty::TraitDtor(true), false) => { |
| // FIXME(16758) Since the struct is unsized, it is hard to |
| // find the drop flag (which is at the end of the struct). |
| // Lets just ignore the flag and pretend everything will be |
| // OK. |
| if type_is_sized(bcx.tcx(), t) { |
| trans_struct_drop_flag(bcx, t, v0) |
| } else { |
| // Give the user a heads up that we are doing something |
| // stupid and dangerous. |
| bcx.sess().warn(&format!("Ignoring drop flag in destructor for {} \ |
| because the struct is unsized. See issue \ |
| #16758", t)); |
| trans_struct_drop(bcx, t, v0) |
| } |
| } |
| (ty::TraitDtor(false), false) => { |
| trans_struct_drop(bcx, t, v0) |
| } |
| (ty::NoDtor, _) | (_, true) => { |
| // No dtor? Just the default case |
| iter_structural_ty(bcx, v0, t, |bb, vv, tt| drop_ty(bb, vv, tt, DebugLoc::None)) |
| } |
| } |
| } |
| ty::TyTrait(..) => { |
| // No support in vtable for distinguishing destroying with |
| // versus without calling Drop::drop. Assert caller is |
| // okay with always calling the Drop impl, if any. |
| assert!(!skip_dtor); |
| let data_ptr = expr::get_dataptr(bcx, v0); |
| let vtable_ptr = Load(bcx, expr::get_meta(bcx, v0)); |
| let dtor = Load(bcx, vtable_ptr); |
| Call(bcx, |
| dtor, |
| &[PointerCast(bcx, Load(bcx, data_ptr), Type::i8p(bcx.ccx()))], |
| DebugLoc::None); |
| bcx |
| } |
| _ => { |
| if bcx.fcx.type_needs_drop(t) { |
| iter_structural_ty(bcx, |
| v0, |
| t, |
| |bb, vv, tt| drop_ty(bb, vv, tt, DebugLoc::None)) |
| } else { |
| bcx |
| } |
| } |
| } |
| } |
