1 // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 // Code relating to taking, dropping, etc as well as type descriptors.
18 use llvm::{ValueRef, True, get_param};
20 use middle::lang_items::ExchangeFreeFnLangItem;
22 use middle::subst::{Subst, Substs};
28 use trans::cleanup::CleanupMethods;
34 use trans::machine::*;
36 use trans::type_::Type;
37 use trans::type_of::{type_of, sizing_type_of, align_of};
38 use middle::ty::{self, Ty};
39 use util::ppaux::{ty_to_short_str, Repr};
42 use arena::TypedArena;
44 use std::ffi::CString;
46 use syntax::parse::token;
48 pub fn trans_exchange_free_dyn<'blk, 'tcx>(cx: Block<'blk, 'tcx>, v: ValueRef,
49 size: ValueRef, align: ValueRef)
50 -> Block<'blk, 'tcx> {
51 let _icx = push_ctxt("trans_exchange_free");
53 callee::trans_lang_call(cx,
54 langcall(cx, None, "", ExchangeFreeFnLangItem),
55 &[PointerCast(cx, v, Type::i8p(ccx)), size, align],
56 Some(expr::Ignore)).bcx
59 pub fn trans_exchange_free<'blk, 'tcx>(cx: Block<'blk, 'tcx>, v: ValueRef,
60 size: u64, align: u32) -> Block<'blk, 'tcx> {
61 trans_exchange_free_dyn(cx, v, C_uint(cx.ccx(), size),
62 C_uint(cx.ccx(), align))
65 pub fn trans_exchange_free_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ptr: ValueRef,
66 content_ty: Ty<'tcx>) -> Block<'blk, 'tcx> {
67 assert!(type_is_sized(bcx.ccx().tcx(), content_ty));
68 let sizing_type = sizing_type_of(bcx.ccx(), content_ty);
69 let content_size = llsize_of_alloc(bcx.ccx(), sizing_type);
71 // `Box<ZeroSizeType>` does not allocate.
72 if content_size != 0 {
73 let content_align = align_of(bcx.ccx(), content_ty);
74 trans_exchange_free(bcx, ptr, content_size, content_align)
80 pub fn get_drop_glue_type<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
81 t: Ty<'tcx>) -> Ty<'tcx> {
83 // Even if there is no dtor for t, there might be one deeper down and we
84 // might need to pass in the vtable ptr.
85 if !type_is_sized(tcx, t) {
88 if !type_needs_drop(tcx, t) {
92 ty::ty_uniq(typ) if !type_needs_drop(tcx, typ)
93 && type_is_sized(tcx, typ) => {
94 let llty = sizing_type_of(ccx, typ);
95 // `Box<ZeroSizeType>` does not allocate.
96 if llsize_of_alloc(ccx, llty) == 0 {
106 pub fn drop_ty<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
109 source_location: Option<NodeInfo>)
110 -> Block<'blk, 'tcx> {
111 // NB: v is an *alias* of type t here, not a direct value.
112 debug!("drop_ty(t={})", t.repr(bcx.tcx()));
113 let _icx = push_ctxt("drop_ty");
114 if type_needs_drop(bcx.tcx(), t) {
116 let glue = get_drop_glue(ccx, t);
117 let glue_type = get_drop_glue_type(ccx, t);
118 let ptr = if glue_type != t {
119 PointerCast(bcx, v, type_of(ccx, glue_type).ptr_to())
124 match source_location {
125 Some(sl) => debuginfo::set_source_location(bcx.fcx, sl.id, sl.span),
126 None => debuginfo::clear_source_location(bcx.fcx)
129 Call(bcx, glue, &[ptr], None);
134 pub fn drop_ty_immediate<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
137 source_location: Option<NodeInfo>)
138 -> Block<'blk, 'tcx> {
139 let _icx = push_ctxt("drop_ty_immediate");
140 let vp = alloca(bcx, type_of(bcx.ccx(), t), "");
141 store_ty(bcx, v, vp, t);
142 drop_ty(bcx, vp, t, source_location)
145 pub fn get_drop_glue<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> ValueRef {
146 debug!("make drop glue for {}", ppaux::ty_to_string(ccx.tcx(), t));
147 let t = get_drop_glue_type(ccx, t);
148 debug!("drop glue type {}", ppaux::ty_to_string(ccx.tcx(), t));
149 match ccx.drop_glues().borrow().get(&t) {
150 Some(&glue) => return glue,
154 let llty = if type_is_sized(ccx.tcx(), t) {
155 type_of(ccx, t).ptr_to()
157 type_of(ccx, ty::mk_uniq(ccx.tcx(), t)).ptr_to()
160 let llfnty = Type::glue_fn(ccx, llty);
162 let (glue, new_sym) = match ccx.available_drop_glues().borrow().get(&t) {
164 let glue = decl_cdecl_fn(ccx, &old_sym[], llfnty, ty::mk_nil(ccx.tcx()));
168 let (sym, glue) = declare_generic_glue(ccx, t, llfnty, "drop");
173 ccx.drop_glues().borrow_mut().insert(t, glue);
175 // To avoid infinite recursion, don't `make_drop_glue` until after we've
176 // added the entry to the `drop_glues` cache.
179 ccx.available_drop_glues().borrow_mut().insert(t, sym);
180 // We're creating a new drop glue, so also generate a body.
181 make_generic_glue(ccx, t, glue, make_drop_glue, "drop");
189 fn trans_struct_drop_flag<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
192 dtor_did: ast::DefId,
193 class_did: ast::DefId,
194 substs: &subst::Substs<'tcx>)
195 -> Block<'blk, 'tcx> {
196 let repr = adt::represent_type(bcx.ccx(), t);
197 let struct_data = if type_is_sized(bcx.tcx(), t) {
200 let llval = GEPi(bcx, v0, &[0, abi::FAT_PTR_ADDR]);
203 let drop_flag = unpack_datum!(bcx, adt::trans_drop_flag_ptr(bcx, &*repr, struct_data));
204 with_cond(bcx, load_ty(bcx, drop_flag.val, bcx.tcx().types.bool), |cx| {
205 trans_struct_drop(cx, t, v0, dtor_did, class_did, substs)
209 fn trans_struct_drop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
212 dtor_did: ast::DefId,
213 class_did: ast::DefId,
214 substs: &subst::Substs<'tcx>)
217 let repr = adt::represent_type(bcx.ccx(), t);
219 // Find and call the actual destructor
220 let dtor_addr = get_res_dtor(bcx.ccx(), dtor_did, t,
223 // The first argument is the "self" argument for drop
224 let params = unsafe {
225 let ty = Type::from_ref(llvm::LLVMTypeOf(dtor_addr));
226 ty.element_type().func_params()
229 let fty = ty::lookup_item_type(bcx.tcx(), dtor_did).ty.subst(bcx.tcx(), substs);
230 let self_ty = match fty.sty {
231 ty::ty_bare_fn(_, ref f) => {
232 let sig = ty::erase_late_bound_regions(bcx.tcx(), &f.sig);
233 assert!(sig.inputs.len() == 1);
236 _ => bcx.sess().bug(&format!("Expected function type, found {}",
237 bcx.ty_to_string(fty))[])
240 let (struct_data, info) = if type_is_sized(bcx.tcx(), t) {
243 let data = GEPi(bcx, v0, &[0, abi::FAT_PTR_ADDR]);
244 let info = GEPi(bcx, v0, &[0, abi::FAT_PTR_EXTRA]);
245 (Load(bcx, data), Some(Load(bcx, info)))
248 adt::fold_variants(bcx, &*repr, struct_data, |variant_cx, st, value| {
249 // Be sure to put all of the fields into a scope so we can use an invoke
250 // instruction to call the user destructor but still call the field
251 // destructors if the user destructor panics.
252 let field_scope = variant_cx.fcx.push_custom_cleanup_scope();
254 // Class dtors have no explicit args, so the params should
255 // just consist of the environment (self).
256 assert_eq!(params.len(), 1);
257 let self_arg = if type_is_fat_ptr(bcx.tcx(), self_ty) {
258 // The dtor expects a fat pointer, so make one, even if we have to fake it.
259 let boxed_ty = ty::mk_open(bcx.tcx(), t);
260 let scratch = datum::rvalue_scratch_datum(bcx, boxed_ty, "__fat_ptr_drop_self");
261 Store(bcx, value, GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_ADDR]));
263 // If we just had a thin pointer, make a fat pointer by sticking
264 // null where we put the unsizing info. This works because t
265 // is a sized type, so we will only unpack the fat pointer, never
266 // use the fake info.
267 info.unwrap_or(C_null(Type::i8p(bcx.ccx()))),
268 GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_EXTRA]));
269 PointerCast(variant_cx, scratch.val, params[0])
271 PointerCast(variant_cx, value, params[0])
273 let args = vec!(self_arg);
275 // Add all the fields as a value which needs to be cleaned at the end of
276 // this scope. Iterate in reverse order so a Drop impl doesn't reverse
277 // the order in which fields get dropped.
278 for (i, ty) in st.fields.iter().enumerate().rev() {
279 let llfld_a = adt::struct_field_ptr(variant_cx, &*st, value, i, false);
281 let val = if type_is_sized(bcx.tcx(), *ty) {
284 let boxed_ty = ty::mk_open(bcx.tcx(), *ty);
285 let scratch = datum::rvalue_scratch_datum(bcx, boxed_ty, "__fat_ptr_drop_field");
286 Store(bcx, llfld_a, GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_ADDR]));
287 Store(bcx, info.unwrap(), GEPi(bcx, scratch.val, &[0, abi::FAT_PTR_EXTRA]));
290 variant_cx.fcx.schedule_drop_mem(cleanup::CustomScope(field_scope),
294 let dtor_ty = ty::mk_ctor_fn(bcx.tcx(),
296 &[get_drop_glue_type(bcx.ccx(), t)],
297 ty::mk_nil(bcx.tcx()));
298 let (_, variant_cx) = invoke(variant_cx, dtor_addr, &args[], dtor_ty, None);
300 variant_cx.fcx.pop_and_trans_custom_cleanup_scope(variant_cx, field_scope);
305 fn size_and_align_of_dst<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, t: Ty<'tcx>, info: ValueRef)
306 -> (ValueRef, ValueRef) {
307 debug!("calculate size of DST: {}; with lost info: {}",
308 bcx.ty_to_string(t), bcx.val_to_string(info));
309 if type_is_sized(bcx.tcx(), t) {
310 let sizing_type = sizing_type_of(bcx.ccx(), t);
311 let size = C_uint(bcx.ccx(), llsize_of_alloc(bcx.ccx(), sizing_type));
312 let align = C_uint(bcx.ccx(), align_of(bcx.ccx(), t));
313 return (size, align);
316 ty::ty_struct(id, substs) => {
318 // First get the size of all statically known fields.
319 // Don't use type_of::sizing_type_of because that expects t to be sized.
320 assert!(!ty::type_is_simd(bcx.tcx(), t));
321 let repr = adt::represent_type(ccx, t);
322 let sizing_type = adt::sizing_type_of(ccx, &*repr, true);
323 let sized_size = C_uint(ccx, llsize_of_alloc(ccx, sizing_type));
324 let sized_align = C_uint(ccx, llalign_of_min(ccx, sizing_type));
326 // Recurse to get the size of the dynamically sized field (must be
328 let fields = ty::struct_fields(bcx.tcx(), id, substs);
329 let last_field = fields[fields.len()-1];
330 let field_ty = last_field.mt.ty;
331 let (unsized_size, unsized_align) = size_and_align_of_dst(bcx, field_ty, info);
333 // Return the sum of sizes and max of aligns.
334 let size = Add(bcx, sized_size, unsized_size);
335 let align = Select(bcx,
336 ICmp(bcx, llvm::IntULT, sized_align, unsized_align),
341 ty::ty_trait(..) => {
342 // info points to the vtable and the second entry in the vtable is the
343 // dynamic size of the object.
344 let info = PointerCast(bcx, info, Type::int(bcx.ccx()).ptr_to());
345 let size_ptr = GEPi(bcx, info, &[1u]);
346 let align_ptr = GEPi(bcx, info, &[2u]);
347 (Load(bcx, size_ptr), Load(bcx, align_ptr))
349 ty::ty_vec(unit_ty, None) => {
350 // The info in this case is the length of the vec, so the size is that
351 // times the unit size.
352 let llunit_ty = sizing_type_of(bcx.ccx(), unit_ty);
353 let unit_size = llsize_of_alloc(bcx.ccx(), llunit_ty);
354 (Mul(bcx, info, C_uint(bcx.ccx(), unit_size)), C_uint(bcx.ccx(), 8u))
356 _ => bcx.sess().bug(&format!("Unexpected unsized type, found {}",
357 bcx.ty_to_string(t))[])
361 fn make_drop_glue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, v0: ValueRef, t: Ty<'tcx>)
362 -> Block<'blk, 'tcx> {
363 // NB: v0 is an *alias* of type t here, not a direct value.
364 let _icx = push_ctxt("make_drop_glue");
366 ty::ty_uniq(content_ty) => {
367 match content_ty.sty {
368 ty::ty_vec(ty, None) => {
369 tvec::make_drop_glue_unboxed(bcx, v0, ty, true)
372 let unit_ty = ty::sequence_element_type(bcx.tcx(), content_ty);
373 tvec::make_drop_glue_unboxed(bcx, v0, unit_ty, true)
375 ty::ty_trait(..) => {
376 let lluniquevalue = GEPi(bcx, v0, &[0, abi::FAT_PTR_ADDR]);
377 // Only drop the value when it is non-null
378 let concrete_ptr = Load(bcx, lluniquevalue);
379 with_cond(bcx, IsNotNull(bcx, concrete_ptr), |bcx| {
380 let dtor_ptr = Load(bcx, GEPi(bcx, v0, &[0, abi::FAT_PTR_EXTRA]));
381 let dtor = Load(bcx, dtor_ptr);
384 &[PointerCast(bcx, lluniquevalue, Type::i8p(bcx.ccx()))],
389 ty::ty_struct(..) if !type_is_sized(bcx.tcx(), content_ty) => {
390 let llval = GEPi(bcx, v0, &[0, abi::FAT_PTR_ADDR]);
391 let llbox = Load(bcx, llval);
392 let not_null = IsNotNull(bcx, llbox);
393 with_cond(bcx, not_null, |bcx| {
394 let bcx = drop_ty(bcx, v0, content_ty, None);
395 let info = GEPi(bcx, v0, &[0, abi::FAT_PTR_EXTRA]);
396 let info = Load(bcx, info);
397 let (llsize, llalign) = size_and_align_of_dst(bcx, content_ty, info);
398 trans_exchange_free_dyn(bcx, llbox, llsize, llalign)
402 assert!(type_is_sized(bcx.tcx(), content_ty));
404 let llbox = Load(bcx, llval);
405 let not_null = IsNotNull(bcx, llbox);
406 with_cond(bcx, not_null, |bcx| {
407 let bcx = drop_ty(bcx, llbox, content_ty, None);
408 trans_exchange_free_ty(bcx, llbox, content_ty)
413 ty::ty_struct(did, substs) | ty::ty_enum(did, substs) => {
415 match ty::ty_dtor(tcx, did) {
416 ty::TraitDtor(dtor, true) => {
417 // FIXME(16758) Since the struct is unsized, it is hard to
418 // find the drop flag (which is at the end of the struct).
419 // Lets just ignore the flag and pretend everything will be
421 if type_is_sized(bcx.tcx(), t) {
422 trans_struct_drop_flag(bcx, t, v0, dtor, did, substs)
424 // Give the user a heads up that we are doing something
425 // stupid and dangerous.
426 bcx.sess().warn(&format!("Ignoring drop flag in destructor for {}\
427 because the struct is unsized. See issue\
429 bcx.ty_to_string(t))[]);
430 trans_struct_drop(bcx, t, v0, dtor, did, substs)
433 ty::TraitDtor(dtor, false) => {
434 trans_struct_drop(bcx, t, v0, dtor, did, substs)
437 // No dtor? Just the default case
438 iter_structural_ty(bcx, v0, t, |bb, vv, tt| drop_ty(bb, vv, tt, None))
442 ty::ty_unboxed_closure(..) => iter_structural_ty(bcx,
445 |bb, vv, tt| drop_ty(bb, vv, tt, None)),
446 ty::ty_trait(..) => {
447 // No need to do a null check here (as opposed to the Box<trait case
448 // above), because this happens for a trait field in an unsized
449 // struct. If anything is null, it is the whole struct and we won't
451 let lluniquevalue = GEPi(bcx, v0, &[0, abi::FAT_PTR_ADDR]);
452 let dtor_ptr = Load(bcx, GEPi(bcx, v0, &[0, abi::FAT_PTR_EXTRA]));
453 let dtor = Load(bcx, dtor_ptr);
456 &[PointerCast(bcx, Load(bcx, lluniquevalue), Type::i8p(bcx.ccx()))],
460 ty::ty_vec(ty, None) => tvec::make_drop_glue_unboxed(bcx, v0, ty, false),
462 assert!(type_is_sized(bcx.tcx(), t));
463 if type_needs_drop(bcx.tcx(), t) &&
464 ty::type_is_structural(t) {
465 iter_structural_ty(bcx, v0, t, |bb, vv, tt| drop_ty(bb, vv, tt, None))
473 // Generates the declaration for (but doesn't emit) a type descriptor.
474 pub fn declare_tydesc<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>)
475 -> tydesc_info<'tcx> {
476 // If emit_tydescs already ran, then we shouldn't be creating any new
478 assert!(!ccx.finished_tydescs().get());
480 let llty = type_of(ccx, t);
482 if ccx.sess().count_type_sizes() {
483 println!("{}\t{}", llsize_of_real(ccx, llty),
484 ppaux::ty_to_string(ccx.tcx(), t));
487 let llsize = llsize_of(ccx, llty);
488 let llalign = llalign_of(ccx, llty);
489 let name = mangle_internal_name_by_type_and_seq(ccx, t, "tydesc");
490 debug!("+++ declare_tydesc {} {}", ppaux::ty_to_string(ccx.tcx(), t), name);
491 let buf = CString::from_slice(name.as_bytes());
493 llvm::LLVMAddGlobal(ccx.llmod(), ccx.tydesc_type().to_ref(),
496 note_unique_llvm_symbol(ccx, name);
498 let ty_name = token::intern_and_get_ident(
499 &ppaux::ty_to_string(ccx.tcx(), t)[]);
500 let ty_name = C_str_slice(ccx, ty_name);
502 debug!("--- declare_tydesc {}", ppaux::ty_to_string(ccx.tcx(), t));
512 fn declare_generic_glue<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>,
513 llfnty: Type, name: &str) -> (String, ValueRef) {
514 let _icx = push_ctxt("declare_generic_glue");
515 let fn_nm = mangle_internal_name_by_type_and_seq(
518 &format!("glue_{}", name)[]);
519 let llfn = decl_cdecl_fn(ccx, &fn_nm[], llfnty, ty::mk_nil(ccx.tcx()));
520 note_unique_llvm_symbol(ccx, fn_nm.clone());
521 return (fn_nm, llfn);
524 fn make_generic_glue<'a, 'tcx, F>(ccx: &CrateContext<'a, 'tcx>,
530 F: for<'blk> FnOnce(Block<'blk, 'tcx>, ValueRef, Ty<'tcx>) -> Block<'blk, 'tcx>,
532 let _icx = push_ctxt("make_generic_glue");
533 let glue_name = format!("glue {} {}", name, ty_to_short_str(ccx.tcx(), t));
534 let _s = StatRecorder::new(ccx, glue_name);
536 let arena = TypedArena::new();
537 let empty_param_substs = Substs::trans_empty();
538 let fcx = new_fn_ctxt(ccx, llfn, ast::DUMMY_NODE_ID, false,
539 ty::FnConverging(ty::mk_nil(ccx.tcx())),
540 &empty_param_substs, None, &arena);
542 let bcx = init_function(&fcx, false, ty::FnConverging(ty::mk_nil(ccx.tcx())));
544 update_linkage(ccx, llfn, None, OriginalTranslation);
546 ccx.stats().n_glues_created.set(ccx.stats().n_glues_created.get() + 1u);
547 // All glue functions take values passed *by alias*; this is a
548 // requirement since in many contexts glue is invoked indirectly and
549 // the caller has no idea if it's dealing with something that can be
552 // llfn is expected be declared to take a parameter of the appropriate
553 // type, so we don't need to explicitly cast the function parameter.
555 let llrawptr0 = get_param(llfn, fcx.arg_pos(0) as c_uint);
556 let bcx = helper(bcx, llrawptr0, t);
557 finish_fn(&fcx, bcx, ty::FnConverging(ty::mk_nil(ccx.tcx())));
562 pub fn emit_tydescs(ccx: &CrateContext) {
563 let _icx = push_ctxt("emit_tydescs");
564 // As of this point, allow no more tydescs to be created.
565 ccx.finished_tydescs().set(true);
566 let glue_fn_ty = Type::generic_glue_fn(ccx).ptr_to();
567 for (_, ti) in ccx.tydescs().borrow().iter() {
568 // Each of the glue functions needs to be cast to a generic type
569 // before being put into the tydesc because we only have a singleton
570 // tydesc type. Then we'll recast each function to its real type when
572 let drop_glue = consts::ptrcast(get_drop_glue(ccx, ti.ty), glue_fn_ty);
573 ccx.stats().n_real_glues.set(ccx.stats().n_real_glues.get() + 1);
575 let tydesc = C_named_struct(ccx.tydesc_type(),
578 drop_glue, // drop_glue
582 let gvar = ti.tydesc;
583 llvm::LLVMSetInitializer(gvar, tydesc);
584 llvm::LLVMSetGlobalConstant(gvar, True);
585 llvm::SetLinkage(gvar, llvm::InternalLinkage);