// Copyright 2012 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. /*! * Handles translation of callees as well as other call-related * things. Callees are a superset of normal rust values and sometimes * have different representations. In particular, top-level fn items * and methods are represented as just a fn ptr and not a full * closure. */ use std::vec; use back::abi; use driver::session; use lib::llvm::ValueRef; use lib::llvm::llvm; use metadata::csearch; use middle::trans::base; use middle::trans::base::*; use middle::trans::build::*; use middle::trans::callee; use middle::trans::closure; use middle::trans::common; use middle::trans::common::*; use middle::trans::datum::*; use middle::trans::datum::Datum; use middle::trans::expr; use middle::trans::glue; use middle::trans::inline; use middle::trans::meth; use middle::trans::monomorphize; use middle::trans::type_of; use middle::ty; use middle::subst::Subst; use middle::typeck; use middle::typeck::coherence::make_substs_for_receiver_types; use util::ppaux::Repr; use middle::trans::type_::Type; use syntax::ast; use syntax::ast_map; use syntax::visit; // Represents a (possibly monomorphized) top-level fn item or method // item. Note that this is just the fn-ptr and is not a Rust closure // value (which is a pair). pub struct FnData { llfn: ValueRef, } pub struct MethodData { llfn: ValueRef, llself: ValueRef, temp_cleanup: Option, self_ty: ty::t, self_mode: ty::SelfMode, } pub enum CalleeData { Closure(Datum), Fn(FnData), Method(MethodData) } pub struct Callee { bcx: block, data: CalleeData } pub fn trans(bcx: block, expr: @ast::expr) -> Callee { let _icx = push_ctxt("trans_callee"); debug!("callee::trans(expr=%s)", expr.repr(bcx.tcx())); // pick out special kinds of expressions that can be called: match expr.node { ast::expr_path(_) => { return trans_def(bcx, bcx.def(expr.id), expr); } _ => {} } // any other expressions are closures: return datum_callee(bcx, expr); fn datum_callee(bcx: block, expr: @ast::expr) -> Callee { let DatumBlock {bcx, datum} = expr::trans_to_datum(bcx, expr); match ty::get(datum.ty).sty { ty::ty_bare_fn(*) => { let llval = datum.to_appropriate_llval(bcx); return Callee {bcx: bcx, data: Fn(FnData {llfn: llval})}; } ty::ty_closure(*) => { return Callee {bcx: bcx, data: Closure(datum)}; } _ => { bcx.tcx().sess.span_bug( expr.span, fmt!("Type of callee is neither bare-fn nor closure: %s", bcx.ty_to_str(datum.ty))); } } } fn fn_callee(bcx: block, fd: FnData) -> Callee { return Callee {bcx: bcx, data: Fn(fd)}; } fn trans_def(bcx: block, def: ast::def, ref_expr: @ast::expr) -> Callee { match def { ast::def_fn(did, _) | ast::def_static_method(did, None, _) => { fn_callee(bcx, trans_fn_ref(bcx, did, ref_expr.id)) } ast::def_static_method(impl_did, Some(trait_did), _) => { fn_callee(bcx, meth::trans_static_method_callee(bcx, impl_did, trait_did, ref_expr.id)) } ast::def_variant(tid, vid) => { // nullary variants are not callable assert!(ty::enum_variant_with_id(bcx.tcx(), tid, vid).args.len() > 0u); fn_callee(bcx, trans_fn_ref(bcx, vid, ref_expr.id)) } ast::def_struct(def_id) => { fn_callee(bcx, trans_fn_ref(bcx, def_id, ref_expr.id)) } ast::def_arg(*) | ast::def_local(*) | ast::def_binding(*) | ast::def_upvar(*) | ast::def_self(*) => { datum_callee(bcx, ref_expr) } ast::def_mod(*) | ast::def_foreign_mod(*) | ast::def_trait(*) | ast::def_static(*) | ast::def_ty(*) | ast::def_prim_ty(*) | ast::def_use(*) | ast::def_typaram_binder(*) | ast::def_region(*) | ast::def_label(*) | ast::def_ty_param(*) | ast::def_self_ty(*) | ast::def_method(*) => { bcx.tcx().sess.span_bug( ref_expr.span, fmt!("Cannot translate def %? \ to a callable thing!", def)); } } } } pub fn trans_fn_ref_to_callee(bcx: block, def_id: ast::def_id, ref_id: ast::node_id) -> Callee { Callee {bcx: bcx, data: Fn(trans_fn_ref(bcx, def_id, ref_id))} } pub fn trans_fn_ref(bcx: block, def_id: ast::def_id, ref_id: ast::node_id) -> FnData { /*! * * Translates a reference (with id `ref_id`) to the fn/method * with id `def_id` into a function pointer. This may require * monomorphization or inlining. */ let _icx = push_ctxt("trans_fn_ref"); let type_params = node_id_type_params(bcx, ref_id); let vtables = node_vtables(bcx, ref_id); debug!("trans_fn_ref(def_id=%s, ref_id=%?, type_params=%s, vtables=%s)", def_id.repr(bcx.tcx()), ref_id, type_params.repr(bcx.tcx()), vtables.repr(bcx.tcx())); trans_fn_ref_with_vtables(bcx, def_id, ref_id, type_params, vtables) } pub fn trans_fn_ref_with_vtables_to_callee( bcx: block, def_id: ast::def_id, ref_id: ast::node_id, type_params: &[ty::t], vtables: Option) -> Callee { Callee {bcx: bcx, data: Fn(trans_fn_ref_with_vtables(bcx, def_id, ref_id, type_params, vtables))} } fn get_impl_resolutions(bcx: block, impl_id: ast::def_id) -> typeck::vtable_res { if impl_id.crate == ast::local_crate { bcx.ccx().maps.vtable_map.get_copy(&impl_id.node) } else { // XXX: This is a temporary hack to work around not properly // exporting information about resolutions for impls. // This doesn't actually work if the trait has param bounds, // but it does allow us to survive the case when it does not. let trait_ref = ty::impl_trait_ref(bcx.tcx(), impl_id).get(); @vec::from_elem(trait_ref.substs.tps.len(), @~[]) } } fn resolve_default_method_vtables(bcx: block, impl_id: ast::def_id, method: &ty::Method, substs: &ty::substs, impl_vtables: Option) -> typeck::vtable_res { // Get the vtables that the impl implements the trait at let trait_vtables = get_impl_resolutions(bcx, impl_id); // Build up a param_substs that we are going to resolve the // trait_vtables under. let param_substs = Some(@param_substs { tys: copy substs.tps, self_ty: substs.self_ty, vtables: impl_vtables, self_vtable: None }); let trait_vtables_fixed = resolve_vtables_under_param_substs( bcx.tcx(), param_substs, trait_vtables); // Now we pull any vtables for parameters on the actual method. let num_method_vtables = method.generics.type_param_defs.len(); let method_vtables = match impl_vtables { Some(vtables) => { let num_impl_type_parameters = vtables.len() - num_method_vtables; vtables.tailn(num_impl_type_parameters).to_owned() }, None => vec::from_elem(num_method_vtables, @~[]) }; @(*trait_vtables_fixed + method_vtables) } pub fn trans_fn_ref_with_vtables( bcx: block, // def_id: ast::def_id, // def id of fn ref_id: ast::node_id, // node id of use of fn; may be zero if N/A type_params: &[ty::t], // values for fn's ty params vtables: Option) // vtables for the call -> FnData { //! // // Translates a reference to a fn/method item, monomorphizing and // inlining as it goes. // // # Parameters // // - `bcx`: the current block where the reference to the fn occurs // - `def_id`: def id of the fn or method item being referenced // - `ref_id`: node id of the reference to the fn/method, if applicable. // This parameter may be zero; but, if so, the resulting value may not // have the right type, so it must be cast before being used. // - `type_params`: values for each of the fn/method's type parameters // - `vtables`: values for each bound on each of the type parameters let _icx = push_ctxt("trans_fn_ref_with_vtables"); let ccx = bcx.ccx(); let tcx = ccx.tcx; debug!("trans_fn_ref_with_vtables(bcx=%s, def_id=%s, ref_id=%?, \ type_params=%s, vtables=%s)", bcx.to_str(), def_id.repr(bcx.tcx()), ref_id, type_params.repr(bcx.tcx()), vtables.repr(bcx.tcx())); assert!(type_params.iter().all(|t| !ty::type_needs_infer(*t))); // Polytype of the function item (may have type params) let fn_tpt = ty::lookup_item_type(tcx, def_id); // For simplicity, we want to use the Subst trait when composing // substitutions for default methods. The subst trait does // substitutions with regions, though, so we put a dummy self // region parameter in to keep it from failing. This is a hack. let substs = ty::substs { self_r: Some(ty::re_empty), self_ty: None, tps: /*bad*/ type_params.to_owned() }; // We need to do a bunch of special handling for default methods. // We need to modify the def_id and our substs in order to monomorphize // the function. let (def_id, opt_impl_did, substs, self_vtable, vtables) = match tcx.provided_method_sources.find(&def_id) { None => (def_id, None, substs, None, vtables), Some(source) => { // There are two relevant substitutions when compiling // default methods. First, there is the substitution for // the type parameters of the impl we are using and the // method we are calling. This substitution is the substs // argument we already have. // In order to compile a default method, though, we need // to consider another substitution: the substitution for // the type parameters on trait; the impl we are using // implements the trait at some particular type // parameters, and we need to substitute for those first. // So, what we need to do is find this substitution and // compose it with the one we already have. let trait_ref = ty::impl_trait_ref(tcx, source.impl_id) .expect("could not find trait_ref for impl with \ default methods"); let method = ty::method(tcx, source.method_id); // Get all of the type params for the receiver let param_defs = method.generics.type_param_defs; let receiver_substs = type_params.initn(param_defs.len()).to_owned(); let receiver_vtables = match vtables { None => @~[], Some(call_vtables) => { @call_vtables.initn(param_defs.len()).to_owned() } }; let self_vtable = typeck::vtable_static(source.impl_id, receiver_substs, receiver_vtables); // Compute the first substitution let first_subst = make_substs_for_receiver_types( tcx, source.impl_id, trait_ref, method); // And compose them let new_substs = first_subst.subst(tcx, &substs); let vtables = resolve_default_method_vtables(bcx, source.impl_id, method, &new_substs, vtables); debug!("trans_fn_with_vtables - default method: \ substs = %s, trait_subst = %s, \ first_subst = %s, new_subst = %s, \ self_vtable = %s, vtables = %s", substs.repr(tcx), trait_ref.substs.repr(tcx), first_subst.repr(tcx), new_substs.repr(tcx), self_vtable.repr(tcx), vtables.repr(tcx)); (source.method_id, Some(source.impl_id), new_substs, Some(self_vtable), Some(vtables)) } }; // Check whether this fn has an inlined copy and, if so, redirect // def_id to the local id of the inlined copy. let def_id = { if def_id.crate != ast::local_crate { inline::maybe_instantiate_inline(ccx, def_id) } else { def_id } }; // We must monomorphise if the fn has type parameters, is a rust // intrinsic, or is a default method. In particular, if we see an // intrinsic that is inlined from a different crate, we want to reemit the // intrinsic instead of trying to call it in the other crate. let must_monomorphise; if type_params.len() > 0 || opt_impl_did.is_some() { must_monomorphise = true; } else if def_id.crate == ast::local_crate { let map_node = session::expect( ccx.sess, ccx.tcx.items.find(&def_id.node), || fmt!("local item should be in ast map")); match *map_node { ast_map::node_foreign_item(_, abis, _, _) => { must_monomorphise = abis.is_intrinsic() } _ => { must_monomorphise = false; } } } else { must_monomorphise = false; } // Create a monomorphic verison of generic functions if must_monomorphise { // Should be either intra-crate or inlined. assert_eq!(def_id.crate, ast::local_crate); let (val, must_cast) = monomorphize::monomorphic_fn(ccx, def_id, &substs, vtables, self_vtable, opt_impl_did, Some(ref_id)); let mut val = val; if must_cast && ref_id != 0 { // Monotype of the REFERENCE to the function (type params // are subst'd) let ref_ty = common::node_id_type(bcx, ref_id); val = PointerCast( bcx, val, type_of::type_of_fn_from_ty(ccx, ref_ty).ptr_to()); } return FnData {llfn: val}; } // Find the actual function pointer. let val = { if def_id.crate == ast::local_crate { // Internal reference. get_item_val(ccx, def_id.node) } else { // External reference. trans_external_path(ccx, def_id, fn_tpt.ty) } }; return FnData {llfn: val}; } // ______________________________________________________________________ // Translating calls pub fn trans_call(in_cx: block, call_ex: @ast::expr, f: @ast::expr, args: CallArgs, id: ast::node_id, dest: expr::Dest) -> block { let _icx = push_ctxt("trans_call"); trans_call_inner(in_cx, call_ex.info(), expr_ty(in_cx, f), node_id_type(in_cx, id), |cx| trans(cx, f), args, Some(dest), DontAutorefArg).bcx } pub fn trans_method_call(in_cx: block, call_ex: @ast::expr, callee_id: ast::node_id, rcvr: @ast::expr, args: CallArgs, dest: expr::Dest) -> block { let _icx = push_ctxt("trans_method_call"); debug!("trans_method_call(call_ex=%s, rcvr=%s)", call_ex.repr(in_cx.tcx()), rcvr.repr(in_cx.tcx())); trans_call_inner( in_cx, call_ex.info(), node_id_type(in_cx, callee_id), expr_ty(in_cx, call_ex), |cx| { match cx.ccx().maps.method_map.find_copy(&call_ex.id) { Some(origin) => { debug!("origin for %s: %s", call_ex.repr(in_cx.tcx()), origin.repr(in_cx.tcx())); meth::trans_method_callee(cx, callee_id, rcvr, origin) } None => { cx.tcx().sess.span_bug(call_ex.span, "method call expr wasn't in method map") } } }, args, Some(dest), DontAutorefArg).bcx } pub fn trans_lang_call(bcx: block, did: ast::def_id, args: &[ValueRef], dest: Option) -> Result { let fty = if did.crate == ast::local_crate { ty::node_id_to_type(bcx.ccx().tcx, did.node) } else { csearch::get_type(bcx.ccx().tcx, did).ty }; let rty = ty::ty_fn_ret(fty); callee::trans_call_inner(bcx, None, fty, rty, |bcx| { trans_fn_ref_with_vtables_to_callee(bcx, did, 0, [], None) }, ArgVals(args), dest, DontAutorefArg) } pub fn trans_lang_call_with_type_params(bcx: block, did: ast::def_id, args: &[ValueRef], type_params: &[ty::t], dest: expr::Dest) -> block { let fty; if did.crate == ast::local_crate { fty = ty::node_id_to_type(bcx.tcx(), did.node); } else { fty = csearch::get_type(bcx.tcx(), did).ty; } let rty = ty::ty_fn_ret(fty); return callee::trans_call_inner( bcx, None, fty, rty, |bcx| { let callee = trans_fn_ref_with_vtables_to_callee(bcx, did, 0, type_params, None); let new_llval; match callee.data { Fn(fn_data) => { let substituted = ty::subst_tps(callee.bcx.tcx(), type_params, None, fty); let llfnty = type_of::type_of(callee.bcx.ccx(), substituted); new_llval = PointerCast(callee.bcx, fn_data.llfn, llfnty); } _ => fail!() } Callee { bcx: callee.bcx, data: Fn(FnData { llfn: new_llval }) } }, ArgVals(args), Some(dest), DontAutorefArg).bcx; } pub fn body_contains_ret(body: &ast::blk) -> bool { let cx = @mut false; visit::visit_block(body, (cx, visit::mk_vt(@visit::Visitor { visit_item: |_i, (_cx, _v)| { }, visit_expr: |e: @ast::expr, (cx, v): (@mut bool, visit::vt<@mut bool>)| { if !*cx { match e.node { ast::expr_ret(_) => *cx = true, _ => visit::visit_expr(e, (cx, v)), } } }, ..*visit::default_visitor() }))); *cx } // See [Note-arg-mode] pub fn trans_call_inner(in_cx: block, call_info: Option, fn_expr_ty: ty::t, ret_ty: ty::t, get_callee: &fn(block) -> Callee, args: CallArgs, dest: Option, autoref_arg: AutorefArg) -> Result { do base::with_scope_result(in_cx, call_info, "call") |cx| { let ret_in_loop = match args { ArgExprs(args) => { args.len() > 0u && match args.last().node { ast::expr_loop_body(@ast::expr { node: ast::expr_fn_block(_, ref body), _ }) => body_contains_ret(body), _ => false } } _ => false }; let callee = get_callee(cx); let mut bcx = callee.bcx; let ccx = cx.ccx(); let ret_flag = if ret_in_loop { let flag = alloca(bcx, Type::bool(), "__ret_flag"); Store(bcx, C_bool(false), flag); Some(flag) } else { None }; let (llfn, llenv) = unsafe { match callee.data { Fn(d) => { (d.llfn, llvm::LLVMGetUndef(Type::opaque_box(ccx).ptr_to().to_ref())) } Method(d) => { // Weird but true: we pass self in the *environment* slot! (d.llfn, d.llself) } Closure(d) => { // Closures are represented as (llfn, llclosure) pair: // load the requisite values out. let pair = d.to_ref_llval(bcx); let llfn = GEPi(bcx, pair, [0u, abi::fn_field_code]); let llfn = Load(bcx, llfn); let llenv = GEPi(bcx, pair, [0u, abi::fn_field_box]); let llenv = Load(bcx, llenv); (llfn, llenv) } } }; let llretslot = trans_ret_slot(bcx, fn_expr_ty, dest); let mut llargs = ~[]; if !ty::type_is_immediate(bcx.tcx(), ret_ty) { llargs.push(llretslot); } llargs.push(llenv); bcx = trans_args(bcx, args, fn_expr_ty, ret_flag, autoref_arg, &mut llargs); // Now that the arguments have finished evaluating, we need to revoke // the cleanup for the self argument match callee.data { Method(d) => { for d.temp_cleanup.iter().advance |&v| { revoke_clean(bcx, v); } } _ => {} } // Uncomment this to debug calls. /* io::println(fmt!("calling: %s", bcx.val_to_str(llfn))); for llargs.iter().advance |llarg| { io::println(fmt!("arg: %s", bcx.val_to_str(*llarg))); } io::println("---"); */ // If the block is terminated, then one or more of the args // has type _|_. Since that means it diverges, the code for // the call itself is unreachable. let (llresult, new_bcx) = base::invoke(bcx, llfn, llargs); bcx = new_bcx; match dest { None => { assert!(ty::type_is_immediate(bcx.tcx(), ret_ty)) } Some(expr::Ignore) => { // drop the value if it is not being saved. if ty::type_needs_drop(bcx.tcx(), ret_ty) { if ty::type_is_immediate(bcx.tcx(), ret_ty) { let llscratchptr = alloc_ty(bcx, ret_ty, "__ret"); Store(bcx, llresult, llscratchptr); bcx = glue::drop_ty(bcx, llscratchptr, ret_ty); } else { bcx = glue::drop_ty(bcx, llretslot, ret_ty); } } } Some(expr::SaveIn(lldest)) => { // If this is an immediate, store into the result location. // (If this was not an immediate, the result will already be // directly written into the output slot.) if ty::type_is_immediate(bcx.tcx(), ret_ty) { Store(bcx, llresult, lldest); } } } if ty::type_is_bot(ret_ty) { Unreachable(bcx); } else if ret_in_loop { let ret_flag_result = bool_to_i1(bcx, Load(bcx, ret_flag.get())); bcx = do with_cond(bcx, ret_flag_result) |bcx| { { let r = (copy bcx.fcx.loop_ret); for r.iter().advance |&(flagptr, _)| { Store(bcx, C_bool(true), flagptr); Store(bcx, C_bool(false), bcx.fcx.llretptr.get()); } } base::cleanup_and_leave(bcx, None, Some(bcx.fcx.get_llreturn())); Unreachable(bcx); bcx } } rslt(bcx, llresult) } } pub enum CallArgs<'self> { ArgExprs(&'self [@ast::expr]), ArgVals(&'self [ValueRef]) } pub fn trans_ret_slot(bcx: block, fn_ty: ty::t, dest: Option) -> ValueRef { let retty = ty::ty_fn_ret(fn_ty); match dest { Some(expr::SaveIn(dst)) => dst, _ => { if ty::type_is_immediate(bcx.tcx(), retty) { unsafe { llvm::LLVMGetUndef(Type::nil().ptr_to().to_ref()) } } else { alloc_ty(bcx, retty, "__trans_ret_slot") } } } } pub fn trans_args(cx: block, args: CallArgs, fn_ty: ty::t, ret_flag: Option, autoref_arg: AutorefArg, llargs: &mut ~[ValueRef]) -> block { let _icx = push_ctxt("trans_args"); let mut temp_cleanups = ~[]; let arg_tys = ty::ty_fn_args(fn_ty); let mut bcx = cx; // First we figure out the caller's view of the types of the arguments. // This will be needed if this is a generic call, because the callee has // to cast her view of the arguments to the caller's view. match args { ArgExprs(arg_exprs) => { let last = arg_exprs.len() - 1u; for arg_exprs.iter().enumerate().advance |(i, arg_expr)| { let arg_val = unpack_result!(bcx, { trans_arg_expr(bcx, arg_tys[i], ty::ByCopy, *arg_expr, &mut temp_cleanups, if i == last { ret_flag } else { None }, autoref_arg) }); llargs.push(arg_val); } } ArgVals(vs) => { llargs.push_all(vs); } } // now that all arguments have been successfully built, we can revoke any // temporary cleanups, as they are only needed if argument construction // should fail (for example, cleanup of copy mode args). for temp_cleanups.iter().advance |c| { revoke_clean(bcx, *c) } bcx } pub enum AutorefArg { DontAutorefArg, DoAutorefArg } // temp_cleanups: cleanups that should run only if failure occurs before the // call takes place: pub fn trans_arg_expr(bcx: block, formal_arg_ty: ty::t, self_mode: ty::SelfMode, arg_expr: @ast::expr, temp_cleanups: &mut ~[ValueRef], ret_flag: Option, autoref_arg: AutorefArg) -> Result { let _icx = push_ctxt("trans_arg_expr"); let ccx = bcx.ccx(); debug!("trans_arg_expr(formal_arg_ty=(%s), self_mode=%?, arg_expr=%s, \ ret_flag=%?)", formal_arg_ty.repr(bcx.tcx()), self_mode, arg_expr.repr(bcx.tcx()), ret_flag.map(|v| bcx.val_to_str(*v))); // translate the arg expr to a datum let arg_datumblock = match ret_flag { None => expr::trans_to_datum(bcx, arg_expr), // If there is a ret_flag, this *must* be a loop body Some(_) => { match arg_expr.node { ast::expr_loop_body( blk @ @ast::expr { node: ast::expr_fn_block(ref decl, ref body), _ }) => { let scratch_ty = expr_ty(bcx, arg_expr); let scratch = alloc_ty(bcx, scratch_ty, "__ret_flag"); let arg_ty = expr_ty(bcx, arg_expr); let sigil = ty::ty_closure_sigil(arg_ty); let bcx = closure::trans_expr_fn( bcx, sigil, decl, body, arg_expr.id, blk.id, Some(ret_flag), expr::SaveIn(scratch)); DatumBlock {bcx: bcx, datum: Datum {val: scratch, ty: scratch_ty, mode: ByRef(RevokeClean)}} } _ => { bcx.sess().impossible_case( arg_expr.span, "ret_flag with non-loop-body expr"); } } } }; let arg_datum = arg_datumblock.datum; let bcx = arg_datumblock.bcx; debug!(" arg datum: %s", arg_datum.to_str(bcx.ccx())); let mut val; if ty::type_is_bot(arg_datum.ty) { // For values of type _|_, we generate an // "undef" value, as such a value should never // be inspected. It's important for the value // to have type lldestty (the callee's expected type). let llformal_arg_ty = type_of::type_of(ccx, formal_arg_ty); unsafe { val = llvm::LLVMGetUndef(llformal_arg_ty.to_ref()); } } else { // FIXME(#3548) use the adjustments table match autoref_arg { DoAutorefArg => { val = arg_datum.to_ref_llval(bcx); } DontAutorefArg => { match self_mode { ty::ByRef => { // This assertion should really be valid, but because // the explicit self code currently passes by-ref, it // does not hold. // //assert !bcx.ccx().maps.moves_map.contains_key( // &arg_expr.id); debug!("by ref arg with type %s, storing to scratch", bcx.ty_to_str(arg_datum.ty)); let scratch = scratch_datum(bcx, arg_datum.ty, "__self", false); arg_datum.store_to_datum(bcx, INIT, scratch); // Technically, ownership of val passes to the callee. // However, we must cleanup should we fail before the // callee is actually invoked. scratch.add_clean(bcx); temp_cleanups.push(scratch.val); val = scratch.to_ref_llval(bcx); } ty::ByCopy => { if ty::type_needs_drop(bcx.tcx(), arg_datum.ty) || arg_datum.appropriate_mode(bcx.tcx()).is_by_ref() { debug!("by copy arg with type %s, storing to scratch", bcx.ty_to_str(arg_datum.ty)); let scratch = scratch_datum(bcx, arg_datum.ty, "__arg", false); arg_datum.store_to_datum(bcx, INIT, scratch); // Technically, ownership of val passes to the callee. // However, we must cleanup should we fail before the // callee is actually invoked. scratch.add_clean(bcx); temp_cleanups.push(scratch.val); match scratch.appropriate_mode(bcx.tcx()) { ByValue => val = Load(bcx, scratch.val), ByRef(_) => val = scratch.val, } } else { debug!("by copy arg with type %s", bcx.ty_to_str(arg_datum.ty)); match arg_datum.mode { ByRef(_) => val = Load(bcx, arg_datum.val), ByValue => val = arg_datum.val, } } } } } } if formal_arg_ty != arg_datum.ty { // this could happen due to e.g. subtyping let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, &formal_arg_ty); debug!("casting actual type (%s) to match formal (%s)", bcx.val_to_str(val), bcx.llty_str(llformal_arg_ty)); val = PointerCast(bcx, val, llformal_arg_ty); } } debug!("--- trans_arg_expr passing %s", bcx.val_to_str(val)); return rslt(bcx, val); }