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 lib::llvm::{llvm, ValueRef, True};
20 use middle::lang_items::{FreeFnLangItem, ExchangeFreeFnLangItem};
21 use middle::trans::adt;
22 use middle::trans::base::*;
23 use middle::trans::build::*;
24 use middle::trans::callee;
25 use middle::trans::cleanup;
26 use middle::trans::cleanup::CleanupMethods;
27 use middle::trans::common::*;
28 use middle::trans::expr;
29 use middle::trans::machine::*;
30 use middle::trans::reflect;
31 use middle::trans::tvec;
32 use middle::trans::type_::Type;
33 use middle::trans::type_of::{type_of, sizing_type_of};
35 use util::ppaux::ty_to_short_str;
38 use arena::TypedArena;
39 use std::c_str::ToCStr;
41 use std::libc::c_uint;
43 use syntax::parse::token;
45 pub fn trans_free<'a>(cx: &'a Block<'a>, v: ValueRef) -> &'a Block<'a> {
46 let _icx = push_ctxt("trans_free");
47 callee::trans_lang_call(cx,
48 langcall(cx, None, "", FreeFnLangItem),
49 [PointerCast(cx, v, Type::i8p(cx.ccx()))],
50 Some(expr::Ignore)).bcx
53 pub fn trans_exchange_free<'a>(cx: &'a Block<'a>, v: ValueRef)
55 let _icx = push_ctxt("trans_exchange_free");
56 callee::trans_lang_call(cx,
57 langcall(cx, None, "", ExchangeFreeFnLangItem),
58 [PointerCast(cx, v, Type::i8p(cx.ccx()))],
59 Some(expr::Ignore)).bcx
62 pub fn take_ty<'a>(bcx: &'a Block<'a>, v: ValueRef, t: ty::t)
64 // NB: v is an *alias* of type t here, not a direct value.
65 let _icx = push_ctxt("take_ty");
66 match ty::get(t).sty {
67 ty::ty_box(_) => incr_refcnt_of_boxed(bcx, v),
68 _ if ty::type_is_structural(t)
69 && ty::type_needs_drop(bcx.tcx(), t) => {
70 iter_structural_ty(bcx, v, t, take_ty)
76 fn get_drop_glue_type(ccx: &CrateContext, t: ty::t) -> ty::t {
78 if !ty::type_needs_drop(tcx, t) {
81 match ty::get(t).sty {
82 ty::ty_box(typ) if !ty::type_needs_drop(tcx, typ) =>
83 ty::mk_box(tcx, ty::mk_i8()),
85 ty::ty_uniq(typ) if !ty::type_needs_drop(tcx, typ) => {
86 let llty = sizing_type_of(ccx, typ);
87 // Unique boxes do not allocate for zero-size types. The standard library may assume
88 // that `free` is never called on the pointer returned for `~ZeroSizeType`.
89 if llsize_of_alloc(ccx, llty) == 0 {
92 ty::mk_uniq(tcx, ty::mk_i8())
96 ty::ty_vec(mt, ty::vstore_uniq) if !ty::type_needs_drop(tcx, mt.ty) =>
97 ty::mk_uniq(tcx, ty::mk_i8()),
103 pub fn drop_ty<'a>(bcx: &'a Block<'a>, v: ValueRef, t: ty::t)
105 // NB: v is an *alias* of type t here, not a direct value.
106 let _icx = push_ctxt("drop_ty");
108 if ty::type_needs_drop(bcx.tcx(), t) {
109 let glue = get_drop_glue(ccx, t);
110 let glue_type = get_drop_glue_type(ccx, t);
111 let ptr = if glue_type != t {
112 PointerCast(bcx, v, type_of(ccx, glue_type).ptr_to())
116 Call(bcx, glue, [ptr], []);
121 pub fn drop_ty_immediate<'a>(bcx: &'a Block<'a>, v: ValueRef, t: ty::t)
123 let _icx = push_ctxt("drop_ty_immediate");
124 let vp = alloca(bcx, type_of(bcx.ccx(), t), "");
129 pub fn get_drop_glue(ccx: &CrateContext, t: ty::t) -> ValueRef {
130 let t = get_drop_glue_type(ccx, t);
131 match ccx.drop_glues.borrow().find(&t) {
132 Some(&glue) => return glue,
136 let llfnty = Type::glue_fn(ccx, type_of(ccx, t).ptr_to());
137 let glue = declare_generic_glue(ccx, t, llfnty, "drop");
139 ccx.drop_glues.borrow_mut().insert(t, glue);
141 make_generic_glue(ccx, t, glue, make_drop_glue, "drop");
146 pub fn lazily_emit_visit_glue(ccx: &CrateContext, ti: @tydesc_info) {
147 let _icx = push_ctxt("lazily_emit_visit_glue");
149 let llfnty = Type::glue_fn(ccx, type_of(ccx, ti.ty).ptr_to());
151 match ti.visit_glue.get() {
154 debug!("+++ lazily_emit_tydesc_glue VISIT {}", ppaux::ty_to_str(ccx.tcx(), ti.ty));
155 let glue_fn = declare_generic_glue(ccx, ti.ty, llfnty, "visit");
156 ti.visit_glue.set(Some(glue_fn));
157 make_generic_glue(ccx, ti.ty, glue_fn, make_visit_glue, "visit");
158 debug!("--- lazily_emit_tydesc_glue VISIT {}", ppaux::ty_to_str(ccx.tcx(), ti.ty));
163 // See [Note-arg-mode]
164 pub fn call_visit_glue(bcx: &Block, v: ValueRef, tydesc: ValueRef,
165 static_ti: Option<@tydesc_info>) {
166 let _icx = push_ctxt("call_tydesc_glue_full");
168 // NB: Don't short-circuit even if this block is unreachable because
169 // GC-based cleanup needs to the see that the roots are live.
170 if bcx.unreachable.get() && !ccx.sess().no_landing_pads() { return; }
172 let static_glue_fn = match static_ti {
175 lazily_emit_visit_glue(ccx, sti);
180 // When static type info is available, avoid casting to a generic pointer.
181 let llrawptr = if static_glue_fn.is_none() {
182 PointerCast(bcx, v, Type::i8p(ccx))
188 match static_glue_fn {
190 // Select out the glue function to call from the tydesc
191 let llfnptr = GEPi(bcx, tydesc, [0u, abi::tydesc_field_visit_glue]);
198 Call(bcx, llfn, [llrawptr], []);
201 fn make_visit_glue<'a>(bcx: &'a Block<'a>, v: ValueRef, t: ty::t)
203 let _icx = push_ctxt("make_visit_glue");
205 let (visitor_trait, object_ty) = match ty::visitor_object_ty(bcx.tcx(),
209 bcx.tcx().sess.fatal(s);
212 let v = PointerCast(bcx, v, type_of(bcx.ccx(), object_ty).ptr_to());
213 bcx = reflect::emit_calls_to_trait_visit_ty(bcx, t, v, visitor_trait.def_id);
217 fn trans_struct_drop_flag<'a>(bcx: &'a Block<'a>,
220 dtor_did: ast::DefId,
221 class_did: ast::DefId,
224 let repr = adt::represent_type(bcx.ccx(), t);
225 let drop_flag = adt::trans_drop_flag_ptr(bcx, repr, v0);
226 with_cond(bcx, IsNotNull(bcx, Load(bcx, drop_flag)), |cx| {
227 trans_struct_drop(cx, t, v0, dtor_did, class_did, substs)
231 fn trans_struct_drop<'a>(bcx: &'a Block<'a>,
234 dtor_did: ast::DefId,
235 class_did: ast::DefId,
238 let repr = adt::represent_type(bcx.ccx(), t);
240 // Find and call the actual destructor
241 let dtor_addr = get_res_dtor(bcx.ccx(), dtor_did,
242 class_did, substs.tps.as_slice());
244 // The second argument is the "self" argument for drop
245 let params = unsafe {
246 let ty = Type::from_ref(llvm::LLVMTypeOf(dtor_addr));
247 ty.element_type().func_params()
250 // Class dtors have no explicit args, so the params should
251 // just consist of the environment (self)
252 assert_eq!(params.len(), 1);
254 // Be sure to put all of the fields into a scope so we can use an invoke
255 // instruction to call the user destructor but still call the field
256 // destructors if the user destructor fails.
257 let field_scope = bcx.fcx.push_custom_cleanup_scope();
259 let self_arg = PointerCast(bcx, v0, *params.get(0));
260 let args = vec!(self_arg);
262 // Add all the fields as a value which needs to be cleaned at the end of
264 let field_tys = ty::struct_fields(bcx.tcx(), class_did, substs);
265 for (i, fld) in field_tys.iter().enumerate() {
266 let llfld_a = adt::trans_field_ptr(bcx, repr, v0, 0, i);
267 bcx.fcx.schedule_drop_mem(cleanup::CustomScope(field_scope),
272 let (_, bcx) = invoke(bcx, dtor_addr, args, [], None);
274 bcx.fcx.pop_and_trans_custom_cleanup_scope(bcx, field_scope)
277 fn make_drop_glue<'a>(bcx: &'a Block<'a>, v0: ValueRef, t: ty::t) -> &'a Block<'a> {
278 // NB: v0 is an *alias* of type t here, not a direct value.
279 let _icx = push_ctxt("make_drop_glue");
280 match ty::get(t).sty {
281 ty::ty_box(body_ty) => {
282 decr_refcnt_maybe_free(bcx, v0, body_ty)
284 ty::ty_uniq(content_ty) => {
285 let llbox = Load(bcx, v0);
286 let not_null = IsNotNull(bcx, llbox);
287 with_cond(bcx, not_null, |bcx| {
288 let bcx = drop_ty(bcx, llbox, content_ty);
289 trans_exchange_free(bcx, llbox)
292 ty::ty_vec(_, ty::vstore_uniq) | ty::ty_str(ty::vstore_uniq) => {
293 make_drop_glue(bcx, v0, tvec::expand_boxed_vec_ty(bcx.tcx(), t))
295 ty::ty_unboxed_vec(_) => {
296 tvec::make_drop_glue_unboxed(bcx, v0, t)
298 ty::ty_struct(did, ref substs) => {
300 match ty::ty_dtor(tcx, did) {
301 ty::TraitDtor(dtor, true) => {
302 trans_struct_drop_flag(bcx, t, v0, dtor, did, substs)
304 ty::TraitDtor(dtor, false) => {
305 trans_struct_drop(bcx, t, v0, dtor, did, substs)
308 // No dtor? Just the default case
309 iter_structural_ty(bcx, v0, t, drop_ty)
313 ty::ty_trait(~ty::TyTrait { store: ty::UniqTraitStore, .. }) => {
314 let lluniquevalue = GEPi(bcx, v0, [0, abi::trt_field_box]);
315 // Only drop the value when it is non-null
316 with_cond(bcx, IsNotNull(bcx, Load(bcx, lluniquevalue)), |bcx| {
317 let dtor_ptr = Load(bcx, GEPi(bcx, v0, [0, abi::trt_field_vtable]));
318 let dtor = Load(bcx, dtor_ptr);
319 Call(bcx, dtor, [PointerCast(bcx, lluniquevalue, Type::i8p(bcx.ccx()))], []);
323 ty::ty_closure(ref f) if f.sigil == ast::OwnedSigil => {
324 let box_cell_v = GEPi(bcx, v0, [0u, abi::fn_field_box]);
325 let env = Load(bcx, box_cell_v);
326 let env_ptr_ty = Type::at_box(bcx.ccx(), Type::i8(bcx.ccx())).ptr_to();
327 let env = PointerCast(bcx, env, env_ptr_ty);
328 with_cond(bcx, IsNotNull(bcx, env), |bcx| {
329 let dtor_ptr = GEPi(bcx, env, [0u, abi::box_field_tydesc]);
330 let dtor = Load(bcx, dtor_ptr);
331 let cdata = GEPi(bcx, env, [0u, abi::box_field_body]);
332 Call(bcx, dtor, [PointerCast(bcx, cdata, Type::i8p(bcx.ccx()))], []);
334 // Free the environment itself
335 trans_exchange_free(bcx, env)
339 if ty::type_needs_drop(bcx.tcx(), t) &&
340 ty::type_is_structural(t) {
341 iter_structural_ty(bcx, v0, t, drop_ty)
349 fn decr_refcnt_maybe_free<'a>(bcx: &'a Block<'a>,
350 box_ptr_ptr: ValueRef,
351 t: ty::t) -> &'a Block<'a> {
352 let _icx = push_ctxt("decr_refcnt_maybe_free");
356 let decr_bcx = fcx.new_temp_block("decr");
357 let free_bcx = fcx.new_temp_block("free");
358 let next_bcx = fcx.new_temp_block("next");
360 let box_ptr = Load(bcx, box_ptr_ptr);
361 let llnotnull = IsNotNull(bcx, box_ptr);
362 CondBr(bcx, llnotnull, decr_bcx.llbb, next_bcx.llbb);
364 let rc_ptr = GEPi(decr_bcx, box_ptr, [0u, abi::box_field_refcnt]);
365 let rc = Sub(decr_bcx, Load(decr_bcx, rc_ptr), C_int(ccx, 1));
366 Store(decr_bcx, rc, rc_ptr);
367 CondBr(decr_bcx, IsNull(decr_bcx, rc), free_bcx.llbb, next_bcx.llbb);
369 let v = Load(free_bcx, box_ptr_ptr);
370 let body = GEPi(free_bcx, v, [0u, abi::box_field_body]);
371 let free_bcx = drop_ty(free_bcx, body, t);
372 let free_bcx = trans_free(free_bcx, v);
373 Br(free_bcx, next_bcx.llbb);
378 fn incr_refcnt_of_boxed<'a>(bcx: &'a Block<'a>,
379 box_ptr_ptr: ValueRef) -> &'a Block<'a> {
380 let _icx = push_ctxt("incr_refcnt_of_boxed");
382 let box_ptr = Load(bcx, box_ptr_ptr);
383 let rc_ptr = GEPi(bcx, box_ptr, [0u, abi::box_field_refcnt]);
384 let rc = Load(bcx, rc_ptr);
385 let rc = Add(bcx, rc, C_int(ccx, 1));
386 Store(bcx, rc, rc_ptr);
391 // Generates the declaration for (but doesn't emit) a type descriptor.
392 pub fn declare_tydesc(ccx: &CrateContext, t: ty::t) -> @tydesc_info {
393 // If emit_tydescs already ran, then we shouldn't be creating any new
395 assert!(!ccx.finished_tydescs.get());
397 let llty = type_of(ccx, t);
399 if ccx.sess().count_type_sizes() {
400 println!("{}\t{}", llsize_of_real(ccx, llty),
401 ppaux::ty_to_str(ccx.tcx(), t));
404 let llsize = llsize_of(ccx, llty);
405 let llalign = llalign_of(ccx, llty);
406 let name = mangle_internal_name_by_type_and_seq(ccx, t, "tydesc");
407 debug!("+++ declare_tydesc {} {}", ppaux::ty_to_str(ccx.tcx(), t), name);
408 let gvar = name.with_c_str(|buf| {
410 llvm::LLVMAddGlobal(ccx.llmod, ccx.tydesc_type().to_ref(), buf)
413 note_unique_llvm_symbol(ccx, name);
415 let ty_name = token::intern_and_get_ident(ppaux::ty_to_str(ccx.tcx(), t));
416 let ty_name = C_str_slice(ccx, ty_name);
418 let inf = @tydesc_info {
424 visit_glue: Cell::new(None),
426 debug!("--- declare_tydesc {}", ppaux::ty_to_str(ccx.tcx(), t));
430 fn declare_generic_glue(ccx: &CrateContext, t: ty::t, llfnty: Type,
431 name: &str) -> ValueRef {
432 let _icx = push_ctxt("declare_generic_glue");
433 let fn_nm = mangle_internal_name_by_type_and_seq(ccx, t, ~"glue_" + name);
434 debug!("{} is for type {}", fn_nm, ppaux::ty_to_str(ccx.tcx(), t));
435 let llfn = decl_cdecl_fn(ccx.llmod, fn_nm, llfnty, ty::mk_nil());
436 note_unique_llvm_symbol(ccx, fn_nm);
440 fn make_generic_glue(ccx: &CrateContext,
443 helper: <'a> |&'a Block<'a>, ValueRef, ty::t|
447 let _icx = push_ctxt("make_generic_glue");
448 let glue_name = format!("glue {} {}", name, ty_to_short_str(ccx.tcx(), t));
449 let _s = StatRecorder::new(ccx, glue_name);
451 let arena = TypedArena::new();
452 let fcx = new_fn_ctxt(ccx, llfn, -1, false, ty::mk_nil(), None, None, &arena);
454 init_function(&fcx, false, ty::mk_nil(), None);
456 lib::llvm::SetLinkage(llfn, lib::llvm::InternalLinkage);
457 ccx.stats.n_glues_created.set(ccx.stats.n_glues_created.get() + 1u);
458 // All glue functions take values passed *by alias*; this is a
459 // requirement since in many contexts glue is invoked indirectly and
460 // the caller has no idea if it's dealing with something that can be
463 // llfn is expected be declared to take a parameter of the appropriate
464 // type, so we don't need to explicitly cast the function parameter.
466 let bcx = fcx.entry_bcx.get().unwrap();
467 let llrawptr0 = unsafe { llvm::LLVMGetParam(llfn, fcx.arg_pos(0) as c_uint) };
468 let bcx = helper(bcx, llrawptr0, t);
469 finish_fn(&fcx, bcx);
474 pub fn emit_tydescs(ccx: &CrateContext) {
475 let _icx = push_ctxt("emit_tydescs");
476 // As of this point, allow no more tydescs to be created.
477 ccx.finished_tydescs.set(true);
478 let glue_fn_ty = Type::generic_glue_fn(ccx).ptr_to();
479 for (_, &val) in ccx.tydescs.borrow().iter() {
482 // Each of the glue functions needs to be cast to a generic type
483 // before being put into the tydesc because we only have a singleton
484 // tydesc type. Then we'll recast each function to its real type when
486 let drop_glue = unsafe {
487 llvm::LLVMConstPointerCast(get_drop_glue(ccx, ti.ty), glue_fn_ty.to_ref())
489 ccx.stats.n_real_glues.set(ccx.stats.n_real_glues.get() + 1);
491 match ti.visit_glue.get() {
493 ccx.stats.n_null_glues.set(ccx.stats.n_null_glues.get() +
499 ccx.stats.n_real_glues.set(ccx.stats.n_real_glues.get() +
501 llvm::LLVMConstPointerCast(v, glue_fn_ty.to_ref())
506 let tydesc = C_named_struct(ccx.tydesc_type(),
509 drop_glue, // drop_glue
510 visit_glue, // visit_glue
514 let gvar = ti.tydesc;
515 llvm::LLVMSetInitializer(gvar, tydesc);
516 llvm::LLVMSetGlobalConstant(gvar, True);
517 lib::llvm::SetLinkage(gvar, lib::llvm::InternalLinkage);