1 // Copyright 2012 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.
12 * Handles translation of callees as well as other call-related
13 * things. Callees are a superset of normal rust values and sometimes
14 * have different representations. In particular, top-level fn items
15 * and methods are represented as just a fn ptr and not a full
19 use arena::TypedArena;
23 use lib::llvm::ValueRef;
25 use metadata::csearch;
28 use middle::subst::{Subst, VecPerParamSpace};
29 use middle::trans::base;
30 use middle::trans::base::*;
31 use middle::trans::build::*;
32 use middle::trans::callee;
33 use middle::trans::cleanup;
34 use middle::trans::cleanup::CleanupMethods;
35 use middle::trans::common;
36 use middle::trans::common::*;
37 use middle::trans::datum::*;
38 use middle::trans::datum::{Datum, KindOps};
39 use middle::trans::expr;
40 use middle::trans::glue;
41 use middle::trans::inline;
42 use middle::trans::foreign;
43 use middle::trans::meth;
44 use middle::trans::monomorphize;
45 use middle::trans::type_::Type;
46 use middle::trans::type_of;
49 use middle::typeck::coherence::make_substs_for_receiver_types;
50 use middle::typeck::MethodCall;
51 use util::ppaux::Repr;
55 use synabi = syntax::abi;
58 pub struct MethodData {
64 Closure(Datum<Lvalue>),
66 // Represents a (possibly monomorphized) top-level fn item or method
67 // item. Note that this is just the fn-ptr and is not a Rust closure
68 // value (which is a pair).
69 Fn(/* llfn */ ValueRef),
71 TraitMethod(MethodData)
74 pub struct Callee<'a> {
75 pub bcx: &'a Block<'a>,
79 fn trans<'a>(bcx: &'a Block<'a>, expr: &ast::Expr) -> Callee<'a> {
80 let _icx = push_ctxt("trans_callee");
81 debug!("callee::trans(expr={})", expr.repr(bcx.tcx()));
83 // pick out special kinds of expressions that can be called:
86 return trans_def(bcx, bcx.def(expr.id), expr);
91 // any other expressions are closures:
92 return datum_callee(bcx, expr);
94 fn datum_callee<'a>(bcx: &'a Block<'a>, expr: &ast::Expr) -> Callee<'a> {
95 let DatumBlock {bcx: mut bcx, datum} = expr::trans(bcx, expr);
96 match ty::get(datum.ty).sty {
97 ty::ty_bare_fn(..) => {
98 let llval = datum.to_llscalarish(bcx);
99 return Callee {bcx: bcx, data: Fn(llval)};
101 ty::ty_closure(..) => {
102 let datum = unpack_datum!(
103 bcx, datum.to_lvalue_datum(bcx, "callee", expr.id));
104 return Callee {bcx: bcx, data: Closure(datum)};
107 bcx.tcx().sess.span_bug(
109 format!("type of callee is neither bare-fn nor closure: \
111 bcx.ty_to_str(datum.ty)).as_slice());
116 fn fn_callee<'a>(bcx: &'a Block<'a>, llfn: ValueRef) -> Callee<'a> {
117 return Callee {bcx: bcx, data: Fn(llfn)};
120 fn trans_def<'a>(bcx: &'a Block<'a>, def: def::Def, ref_expr: &ast::Expr)
124 def::DefStaticMethod(did, def::FromImpl(_), _) => {
125 fn_callee(bcx, trans_fn_ref(bcx, did, ExprId(ref_expr.id)))
127 def::DefStaticMethod(impl_did,
128 def::FromTrait(trait_did),
130 fn_callee(bcx, meth::trans_static_method_callee(bcx, impl_did,
134 def::DefVariant(tid, vid, _) => {
135 // nullary variants are not callable
136 assert!(ty::enum_variant_with_id(bcx.tcx(),
138 vid).args.len() > 0u);
139 fn_callee(bcx, trans_fn_ref(bcx, vid, ExprId(ref_expr.id)))
141 def::DefStruct(def_id) => {
142 fn_callee(bcx, trans_fn_ref(bcx, def_id, ExprId(ref_expr.id)))
147 def::DefBinding(..) |
148 def::DefUpvar(..) => {
149 datum_callee(bcx, ref_expr)
151 def::DefMod(..) | def::DefForeignMod(..) | def::DefTrait(..) |
152 def::DefTy(..) | def::DefPrimTy(..) |
153 def::DefUse(..) | def::DefTyParamBinder(..) |
154 def::DefRegion(..) | def::DefLabel(..) | def::DefTyParam(..) |
155 def::DefSelfTy(..) | def::DefMethod(..) => {
156 bcx.tcx().sess.span_bug(
158 format!("cannot translate def {:?} \
159 to a callable thing!", def).as_slice());
165 pub fn trans_fn_ref(bcx: &Block, def_id: ast::DefId, node: ExprOrMethodCall) -> ValueRef {
167 * Translates a reference (with id `ref_id`) to the fn/method
168 * with id `def_id` into a function pointer. This may require
169 * monomorphization or inlining.
172 let _icx = push_ctxt("trans_fn_ref");
174 let substs = node_id_substs(bcx, node);
175 let vtable_key = match node {
176 ExprId(id) => MethodCall::expr(id),
177 MethodCall(method_call) => method_call
179 let vtables = node_vtables(bcx, vtable_key);
180 debug!("trans_fn_ref(def_id={}, node={:?}, substs={}, vtables={})",
181 def_id.repr(bcx.tcx()),
183 substs.repr(bcx.tcx()),
184 vtables.repr(bcx.tcx()));
185 trans_fn_ref_with_vtables(bcx, def_id, node, substs, vtables)
188 fn trans_fn_ref_with_vtables_to_callee<'a>(bcx: &'a Block<'a>,
191 substs: subst::Substs,
192 vtables: typeck::vtable_res)
195 data: Fn(trans_fn_ref_with_vtables(bcx, def_id, ExprId(ref_id),
199 fn resolve_default_method_vtables(bcx: &Block,
201 substs: &subst::Substs,
202 impl_vtables: typeck::vtable_res)
203 -> typeck::vtable_res
205 // Get the vtables that the impl implements the trait at
206 let impl_res = ty::lookup_impl_vtables(bcx.tcx(), impl_id);
208 // Build up a param_substs that we are going to resolve the
209 // trait_vtables under.
210 let param_substs = param_substs {
211 substs: (*substs).clone(),
212 vtables: impl_vtables.clone()
215 let mut param_vtables = resolve_vtables_under_param_substs(
216 bcx.tcx(), ¶m_substs, &impl_res);
218 // Now we pull any vtables for parameters on the actual method.
220 .get_mut_vec(subst::FnSpace)
222 impl_vtables.get_vec(subst::FnSpace).as_slice());
227 /// Translates the adapter that deconstructs a `Box<Trait>` object into
228 /// `Trait` so that a by-value self method can be called.
229 pub fn trans_unboxing_shim(bcx: &Block,
230 llshimmedfn: ValueRef,
232 method_id: ast::DefId,
233 substs: subst::Substs)
235 let _icx = push_ctxt("trans_unboxing_shim");
239 // Transform the self type to `Box<self_type>`.
240 let self_type = *method.fty.sig.inputs.get(0);
241 let boxed_self_type = ty::mk_uniq(tcx, self_type);
242 let boxed_function_type = ty::FnSig {
243 binder_id: method.fty.sig.binder_id,
244 inputs: method.fty.sig.inputs.iter().enumerate().map(|(i, typ)| {
251 output: method.fty.sig.output,
254 let boxed_function_type = ty::BareFnTy {
255 fn_style: method.fty.fn_style,
257 sig: boxed_function_type,
259 let boxed_function_type =
260 ty::mk_bare_fn(tcx, boxed_function_type).subst(tcx, &substs);
262 ty::mk_bare_fn(tcx, method.fty.clone()).subst(tcx, &substs);
264 let function_name = ty::with_path(tcx, method_id, |path| {
265 link::mangle_internal_name_by_path_and_seq(path, "unboxing_shim")
267 let llfn = decl_internal_rust_fn(ccx,
269 function_name.as_slice());
271 let block_arena = TypedArena::new();
272 let empty_param_substs = param_substs::empty();
273 let return_type = ty::ty_fn_ret(boxed_function_type);
274 let fcx = new_fn_ctxt(ccx,
282 init_function(&fcx, false, return_type);
284 // Create the substituted versions of the self type.
285 let mut bcx = fcx.entry_bcx.borrow().clone().unwrap();
286 let arg_scope = fcx.push_custom_cleanup_scope();
287 let arg_scope_id = cleanup::CustomScope(arg_scope);
288 let boxed_arg_types = ty::ty_fn_args(boxed_function_type);
289 let boxed_self_type = *boxed_arg_types.get(0);
290 let arg_types = ty::ty_fn_args(function_type);
291 let self_type = *arg_types.get(0);
292 let boxed_self_kind = arg_kind(&fcx, boxed_self_type);
294 // Create a datum for self.
295 let llboxedself = unsafe {
296 llvm::LLVMGetParam(fcx.llfn, fcx.arg_pos(0) as u32)
298 let llboxedself = Datum::new(llboxedself,
303 llboxedself.to_lvalue_datum_in_scope(bcx,
307 // This `Load` is needed because lvalue data are always by-ref.
308 let llboxedself = Load(bcx, boxed_self.val);
310 let llself = if type_is_immediate(ccx, self_type) {
311 let llboxedself = Load(bcx, llboxedself);
312 immediate_rvalue(llboxedself, self_type)
314 let llself = rvalue_scratch_datum(bcx, self_type, "self");
315 memcpy_ty(bcx, llself.val, llboxedself, self_type);
319 // Make sure we don't free the box twice!
320 boxed_self.kind.post_store(bcx, boxed_self.val, boxed_self_type);
322 // Schedule a cleanup to free the box.
323 fcx.schedule_free_value(arg_scope_id,
325 cleanup::HeapExchange,
328 // Now call the function.
329 let mut llshimmedargs = vec!(llself.val);
330 for i in range(1, arg_types.len()) {
331 llshimmedargs.push(unsafe {
332 llvm::LLVMGetParam(fcx.llfn, fcx.arg_pos(i) as u32)
335 bcx = trans_call_inner(bcx,
341 data: Fn(llshimmedfn),
344 ArgVals(llshimmedargs.as_slice()),
345 match fcx.llretptr.get() {
347 Some(llretptr) => Some(expr::SaveIn(llretptr)),
350 bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_scope);
351 finish_fn(&fcx, bcx);
356 pub fn trans_fn_ref_with_vtables(
358 def_id: ast::DefId, // def id of fn
359 node: ExprOrMethodCall, // node id of use of fn; may be zero if N/A
360 substs: subst::Substs, // values for fn's ty params
361 vtables: typeck::vtable_res) // vtables for the call
365 * Translates a reference to a fn/method item, monomorphizing and
366 * inlining as it goes.
370 * - `bcx`: the current block where the reference to the fn occurs
371 * - `def_id`: def id of the fn or method item being referenced
372 * - `node`: node id of the reference to the fn/method, if applicable.
373 * This parameter may be zero; but, if so, the resulting value may not
374 * have the right type, so it must be cast before being used.
375 * - `substs`: values for each of the fn/method's parameters
376 * - `vtables`: values for each bound on each of the type parameters
379 let _icx = push_ctxt("trans_fn_ref_with_vtables");
383 debug!("trans_fn_ref_with_vtables(bcx={}, def_id={}, node={:?}, \
384 substs={}, vtables={})",
391 assert!(substs.types.all(|t| !ty::type_needs_infer(*t)));
393 // Polytype of the function item (may have type params)
394 let fn_tpt = ty::lookup_item_type(tcx, def_id);
396 // Load the info for the appropriate trait if necessary.
397 match ty::trait_of_method(tcx, def_id) {
400 ty::populate_implementations_for_trait_if_necessary(tcx, trait_id)
404 // We need to do a bunch of special handling for default methods.
405 // We need to modify the def_id and our substs in order to monomorphize
407 let (is_default, def_id, substs, vtables) =
408 match ty::provided_source(tcx, def_id) {
409 None => (false, def_id, substs, vtables),
411 // There are two relevant substitutions when compiling
412 // default methods. First, there is the substitution for
413 // the type parameters of the impl we are using and the
414 // method we are calling. This substitution is the substs
415 // argument we already have.
416 // In order to compile a default method, though, we need
417 // to consider another substitution: the substitution for
418 // the type parameters on trait; the impl we are using
419 // implements the trait at some particular type
420 // parameters, and we need to substitute for those first.
421 // So, what we need to do is find this substitution and
422 // compose it with the one we already have.
424 let impl_id = ty::method(tcx, def_id).container_id();
425 let method = ty::method(tcx, source_id);
426 let trait_ref = ty::impl_trait_ref(tcx, impl_id)
427 .expect("could not find trait_ref for impl with \
430 // Compute the first substitution
431 let first_subst = make_substs_for_receiver_types(
432 tcx, &*trait_ref, &*method);
435 let new_substs = first_subst.subst(tcx, &substs);
437 debug!("trans_fn_with_vtables - default method: \
438 substs = {}, trait_subst = {}, \
439 first_subst = {}, new_subst = {}, \
441 substs.repr(tcx), trait_ref.substs.repr(tcx),
442 first_subst.repr(tcx), new_substs.repr(tcx),
446 resolve_default_method_vtables(bcx, impl_id, &substs, vtables);
448 debug!("trans_fn_with_vtables - default method: \
450 param_vtables.repr(tcx));
452 (true, source_id, new_substs, param_vtables)
456 // Check whether this fn has an inlined copy and, if so, redirect
457 // def_id to the local id of the inlined copy.
459 if def_id.krate != ast::LOCAL_CRATE {
460 inline::maybe_instantiate_inline(ccx, def_id)
466 // We must monomorphise if the fn has type parameters, is a rust
467 // intrinsic, or is a default method. In particular, if we see an
468 // intrinsic that is inlined from a different crate, we want to reemit the
469 // intrinsic instead of trying to call it in the other crate.
470 let must_monomorphise = if !substs.types.is_empty() || is_default {
472 } else if def_id.krate == ast::LOCAL_CRATE {
473 let map_node = session::expect(
475 tcx.map.find(def_id.node),
476 || "local item should be in ast map".to_string());
479 ast_map::NodeForeignItem(_) => {
480 tcx.map.get_foreign_abi(def_id.node) == synabi::RustIntrinsic
488 // Create a monomorphic version of generic functions
489 if must_monomorphise {
490 // Should be either intra-crate or inlined.
491 assert_eq!(def_id.krate, ast::LOCAL_CRATE);
493 let opt_ref_id = match node {
494 ExprId(id) => if id != 0 { Some(id) } else { None },
495 MethodCall(_) => None,
498 let (val, must_cast) =
499 monomorphize::monomorphic_fn(ccx, def_id, &substs,
500 vtables, opt_ref_id);
502 if must_cast && node != ExprId(0) {
503 // Monotype of the REFERENCE to the function (type params
505 let ref_ty = match node {
506 ExprId(id) => node_id_type(bcx, id),
507 MethodCall(method_call) => {
508 let t = bcx.tcx().method_map.borrow().get(&method_call).ty;
509 monomorphize_type(bcx, t)
514 bcx, val, type_of::type_of_fn_from_ty(ccx, ref_ty).ptr_to());
519 // Find the actual function pointer.
521 if def_id.krate == ast::LOCAL_CRATE {
522 // Internal reference.
523 get_item_val(ccx, def_id.node)
525 // External reference.
526 trans_external_path(ccx, def_id, fn_tpt.ty)
530 // This is subtle and surprising, but sometimes we have to bitcast
531 // the resulting fn pointer. The reason has to do with external
532 // functions. If you have two crates that both bind the same C
533 // library, they may not use precisely the same types: for
534 // example, they will probably each declare their own structs,
535 // which are distinct types from LLVM's point of view (nominal
538 // Now, if those two crates are linked into an application, and
539 // they contain inlined code, you can wind up with a situation
540 // where both of those functions wind up being loaded into this
541 // application simultaneously. In that case, the same function
542 // (from LLVM's point of view) requires two types. But of course
543 // LLVM won't allow one function to have two types.
545 // What we currently do, therefore, is declare the function with
546 // one of the two types (whichever happens to come first) and then
547 // bitcast as needed when the function is referenced to make sure
548 // it has the type we expect.
550 // This can occur on either a crate-local or crate-external
551 // reference. It also occurs when testing libcore and in some
552 // other weird situations. Annoying.
553 let llty = type_of::type_of_fn_from_ty(ccx, fn_tpt.ty);
554 let llptrty = llty.ptr_to();
555 if val_ty(val) != llptrty {
556 val = BitCast(bcx, val, llptrty);
562 // ______________________________________________________________________
565 pub fn trans_call<'a>(
566 in_cx: &'a Block<'a>,
572 let _icx = push_ctxt("trans_call");
573 trans_call_inner(in_cx,
574 Some(common::expr_info(call_ex)),
576 |cx, _| trans(cx, f),
581 pub fn trans_method_call<'a>(
588 let _icx = push_ctxt("trans_method_call");
589 debug!("trans_method_call(call_ex={})", call_ex.repr(bcx.tcx()));
590 let method_call = MethodCall::expr(call_ex.id);
591 let method_ty = bcx.tcx().method_map.borrow().get(&method_call).ty;
594 Some(common::expr_info(call_ex)),
595 monomorphize_type(bcx, method_ty),
596 |cx, arg_cleanup_scope| {
597 meth::trans_method_callee(cx, method_call, Some(rcvr), arg_cleanup_scope)
603 pub fn trans_lang_call<'a>(
607 dest: Option<expr::Dest>)
609 let fty = if did.krate == ast::LOCAL_CRATE {
610 ty::node_id_to_type(bcx.tcx(), did.node)
612 csearch::get_type(bcx.tcx(), did).ty
614 callee::trans_call_inner(bcx,
618 trans_fn_ref_with_vtables_to_callee(bcx,
621 subst::Substs::empty(),
622 VecPerParamSpace::empty())
628 pub fn trans_call_inner<'a>(
630 call_info: Option<NodeInfo>,
632 get_callee: |bcx: &'a Block<'a>,
633 arg_cleanup_scope: cleanup::ScopeId|
636 dest: Option<expr::Dest>)
639 * This behemoth of a function translates function calls.
640 * Unfortunately, in order to generate more efficient LLVM
641 * output at -O0, it has quite a complex signature (refactoring
642 * this into two functions seems like a good idea).
644 * In particular, for lang items, it is invoked with a dest of
645 * None, and in that case the return value contains the result of
646 * the fn. The lang item must not return a structural type or else
647 * all heck breaks loose.
649 * For non-lang items, `dest` is always Some, and hence the result
650 * is written into memory somewhere. Nonetheless we return the
651 * actual return value of the function.
654 // Introduce a temporary cleanup scope that will contain cleanups
655 // for the arguments while they are being evaluated. The purpose
656 // this cleanup is to ensure that, should a failure occur while
657 // evaluating argument N, the values for arguments 0...N-1 are all
658 // cleaned up. If no failure occurs, the values are handed off to
659 // the callee, and hence none of the cleanups in this temporary
660 // scope will ever execute.
663 let arg_cleanup_scope = fcx.push_custom_cleanup_scope();
665 let callee = get_callee(bcx, cleanup::CustomScope(arg_cleanup_scope));
666 let mut bcx = callee.bcx;
668 let (llfn, llenv, llself) = match callee.data {
673 (d.llfn, None, Some(d.llself))
676 // Closures are represented as (llfn, llclosure) pair:
677 // load the requisite values out.
678 let pair = d.to_llref();
679 let llfn = GEPi(bcx, pair, [0u, abi::fn_field_code]);
680 let llfn = Load(bcx, llfn);
681 let llenv = GEPi(bcx, pair, [0u, abi::fn_field_box]);
682 let llenv = Load(bcx, llenv);
683 (llfn, Some(llenv), None)
687 let (abi, ret_ty) = match ty::get(callee_ty).sty {
688 ty::ty_bare_fn(ref f) => (f.abi, f.sig.output),
689 ty::ty_closure(ref f) => (synabi::Rust, f.sig.output),
690 _ => fail!("expected bare rust fn or closure in trans_call_inner")
692 let is_rust_fn = abi == synabi::Rust || abi == synabi::RustIntrinsic;
694 // Generate a location to store the result. If the user does
695 // not care about the result, just make a stack slot.
696 let opt_llretslot = match dest {
698 assert!(!type_of::return_uses_outptr(ccx, ret_ty));
701 Some(expr::SaveIn(dst)) => Some(dst),
702 Some(expr::Ignore) => {
703 if !type_is_zero_size(ccx, ret_ty) {
704 Some(alloc_ty(bcx, ret_ty, "__llret"))
706 let llty = type_of::type_of(ccx, ret_ty);
707 Some(C_undef(llty.ptr_to()))
712 let mut llresult = unsafe {
713 llvm::LLVMGetUndef(Type::nil(ccx).ptr_to().to_ref())
716 // The code below invokes the function, using either the Rust
717 // conventions (if it is a rust fn) or the native conventions
718 // (otherwise). The important part is that, when all is sad
719 // and done, either the return value of the function will have been
720 // written in opt_llretslot (if it is Some) or `llresult` will be
721 // set appropriately (otherwise).
723 let mut llargs = Vec::new();
725 // Push the out-pointer if we use an out-pointer for this
726 // return type, otherwise push "undef".
727 if type_of::return_uses_outptr(ccx, ret_ty) {
728 llargs.push(opt_llretslot.unwrap());
731 // Push the environment (or a trait object's self).
732 match (llenv, llself) {
733 (Some(llenv), None) => {
736 (None, Some(llself)) => llargs.push(llself),
740 // Push the arguments.
741 bcx = trans_args(bcx, args, callee_ty, &mut llargs,
742 cleanup::CustomScope(arg_cleanup_scope),
745 fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
747 // Invoke the actual rust fn and update bcx/llresult.
748 let (llret, b) = base::invoke(bcx,
756 // If the Rust convention for this type is return via
757 // the return value, copy it into llretslot.
758 match opt_llretslot {
760 if !type_of::return_uses_outptr(bcx.ccx(), ret_ty) &&
761 !type_is_zero_size(bcx.ccx(), ret_ty)
763 Store(bcx, llret, llretslot);
769 // Lang items are the only case where dest is None, and
770 // they are always Rust fns.
771 assert!(dest.is_some());
773 let mut llargs = Vec::new();
774 let arg_tys = match args {
775 ArgExprs(a) => a.iter().map(|x| expr_ty(bcx, &**x)).collect(),
776 _ => fail!("expected arg exprs.")
778 bcx = trans_args(bcx, args, callee_ty, &mut llargs,
779 cleanup::CustomScope(arg_cleanup_scope), false);
780 fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
781 bcx = foreign::trans_native_call(bcx, callee_ty,
782 llfn, opt_llretslot.unwrap(),
783 llargs.as_slice(), arg_tys);
786 // If the caller doesn't care about the result of this fn call,
787 // drop the temporary slot we made.
790 assert!(!type_of::return_uses_outptr(bcx.ccx(), ret_ty));
792 Some(expr::Ignore) => {
793 // drop the value if it is not being saved.
794 bcx = glue::drop_ty(bcx, opt_llretslot.unwrap(), ret_ty);
796 Some(expr::SaveIn(_)) => { }
799 if ty::type_is_bot(ret_ty) {
803 Result::new(bcx, llresult)
806 pub enum CallArgs<'a> {
807 // Supply value of arguments as a list of expressions that must be
808 // translated. This is used in the common case of `foo(bar, qux)`.
809 ArgExprs(&'a [Gc<ast::Expr>]),
811 // Supply value of arguments as a list of LLVM value refs; frequently
812 // used with lang items and so forth, when the argument is an internal
814 ArgVals(&'a [ValueRef]),
816 // For overloaded operators: `(lhs, Option(rhs, rhs_id))`. `lhs`
817 // is the left-hand-side and `rhs/rhs_id` is the datum/expr-id of
818 // the right-hand-side (if any).
819 ArgOverloadedOp(Datum<Expr>, Option<(Datum<Expr>, ast::NodeId)>),
822 fn trans_args<'a>(cx: &'a Block<'a>,
825 llargs: &mut Vec<ValueRef> ,
826 arg_cleanup_scope: cleanup::ScopeId,
829 let _icx = push_ctxt("trans_args");
830 let arg_tys = ty::ty_fn_args(fn_ty);
831 let variadic = ty::fn_is_variadic(fn_ty);
835 // First we figure out the caller's view of the types of the arguments.
836 // This will be needed if this is a generic call, because the callee has
837 // to cast her view of the arguments to the caller's view.
839 ArgExprs(arg_exprs) => {
840 let num_formal_args = arg_tys.len();
841 for (i, arg_expr) in arg_exprs.iter().enumerate() {
842 if i == 0 && ignore_self {
845 let arg_ty = if i >= num_formal_args {
847 expr_ty_adjusted(cx, &**arg_expr)
852 let arg_datum = unpack_datum!(bcx, expr::trans(bcx, &**arg_expr));
853 llargs.push(unpack_result!(bcx, {
854 trans_arg_datum(bcx, arg_ty, arg_datum,
860 ArgOverloadedOp(lhs, rhs) => {
863 llargs.push(unpack_result!(bcx, {
864 trans_arg_datum(bcx, *arg_tys.get(0), lhs,
870 Some((rhs, rhs_id)) => {
871 assert_eq!(arg_tys.len(), 2);
873 llargs.push(unpack_result!(bcx, {
874 trans_arg_datum(bcx, *arg_tys.get(1), rhs,
876 DoAutorefArg(rhs_id))
879 None => assert_eq!(arg_tys.len(), 1)
890 pub enum AutorefArg {
892 DoAutorefArg(ast::NodeId)
895 pub fn trans_arg_datum<'a>(
897 formal_arg_ty: ty::t,
898 arg_datum: Datum<Expr>,
899 arg_cleanup_scope: cleanup::ScopeId,
900 autoref_arg: AutorefArg)
902 let _icx = push_ctxt("trans_arg_datum");
906 debug!("trans_arg_datum({})",
907 formal_arg_ty.repr(bcx.tcx()));
909 let arg_datum_ty = arg_datum.ty;
911 debug!(" arg datum: {}", arg_datum.to_str(bcx.ccx()));
914 if ty::type_is_bot(arg_datum_ty) {
915 // For values of type _|_, we generate an
916 // "undef" value, as such a value should never
917 // be inspected. It's important for the value
918 // to have type lldestty (the callee's expected type).
919 let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, formal_arg_ty);
921 val = llvm::LLVMGetUndef(llformal_arg_ty.to_ref());
924 // FIXME(#3548) use the adjustments table
926 DoAutorefArg(arg_id) => {
927 // We will pass argument by reference
928 // We want an lvalue, so that we can pass by reference and
929 let arg_datum = unpack_datum!(
930 bcx, arg_datum.to_lvalue_datum(bcx, "arg", arg_id));
934 // Make this an rvalue, since we are going to be
935 // passing ownership.
936 let arg_datum = unpack_datum!(
937 bcx, arg_datum.to_rvalue_datum(bcx, "arg"));
939 // Now that arg_datum is owned, get it into the appropriate
940 // mode (ref vs value).
941 let arg_datum = unpack_datum!(
942 bcx, arg_datum.to_appropriate_datum(bcx));
944 // Technically, ownership of val passes to the callee.
945 // However, we must cleanup should we fail before the
946 // callee is actually invoked.
947 val = arg_datum.add_clean(bcx.fcx, arg_cleanup_scope);
951 if formal_arg_ty != arg_datum_ty {
952 // this could happen due to e.g. subtyping
953 let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, formal_arg_ty);
954 debug!("casting actual type ({}) to match formal ({})",
955 bcx.val_to_str(val), bcx.llty_str(llformal_arg_ty));
956 val = PointerCast(bcx, val, llformal_arg_ty);
960 debug!("--- trans_arg_datum passing {}", bcx.val_to_str(val));
961 Result::new(bcx, val)