1 // Copyright 2012-2014 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 use back::{abi, link};
13 use llvm::{ValueRef, CallConv, get_param};
15 use middle::weak_lang_items;
17 use trans::attributes;
18 use trans::base::{llvm_linkage_by_name, push_ctxt};
23 use trans::debuginfo::DebugLoc;
27 use trans::monomorphize;
28 use trans::type_::Type;
29 use trans::type_of::*;
31 use middle::ty::{self, Ty};
32 use middle::subst::Substs;
36 use syntax::abi::{Cdecl, Aapcs, C, Win64, Abi};
37 use syntax::abi::{RustIntrinsic, Rust, RustCall, Stdcall, Fastcall, System};
38 use syntax::codemap::Span;
39 use syntax::parse::token::{InternedString, special_idents};
42 use syntax::print::pprust;
44 ///////////////////////////////////////////////////////////////////////////
47 struct ForeignTypes<'tcx> {
48 /// Rust signature of the function
49 fn_sig: ty::FnSig<'tcx>,
51 /// Adapter object for handling native ABI rules (trust me, you
52 /// don't want to know)
55 /// LLVM types that will appear on the foreign function
59 struct LlvmSignature {
60 // LLVM versions of the types of this function's arguments.
61 llarg_tys: Vec<Type> ,
63 // LLVM version of the type that this function returns. Note that
64 // this *may not be* the declared return type of the foreign
65 // function, because the foreign function may opt to return via an
69 /// True if there is a return value (not bottom, not unit)
74 ///////////////////////////////////////////////////////////////////////////
75 // Calls to external functions
77 pub fn llvm_calling_convention(ccx: &CrateContext,
78 abi: Abi) -> CallConv {
79 match ccx.sess().target.target.adjust_abi(abi) {
81 // Intrinsics are emitted at the call site
82 ccx.sess().bug("asked to register intrinsic fn");
86 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
87 ccx.sess().unimpl("foreign functions with Rust ABI");
91 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
92 ccx.sess().unimpl("foreign functions with RustCall ABI");
95 // It's the ABI's job to select this, not us.
96 System => ccx.sess().bug("system abi should be selected elsewhere"),
98 Stdcall => llvm::X86StdcallCallConv,
99 Fastcall => llvm::X86FastcallCallConv,
100 C => llvm::CCallConv,
101 Win64 => llvm::X86_64_Win64,
103 // These API constants ought to be more specific...
104 Cdecl => llvm::CCallConv,
105 Aapcs => llvm::CCallConv,
109 pub fn register_static(ccx: &CrateContext,
110 foreign_item: &ast::ForeignItem) -> ValueRef {
111 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
112 let llty = type_of::type_of(ccx, ty);
114 let ident = link_name(foreign_item);
115 match attr::first_attr_value_str_by_name(&foreign_item.attrs,
117 // If this is a static with a linkage specified, then we need to handle
118 // it a little specially. The typesystem prevents things like &T and
119 // extern "C" fn() from being non-null, so we can't just declare a
120 // static and call it a day. Some linkages (like weak) will make it such
121 // that the static actually has a null value.
123 let linkage = match llvm_linkage_by_name(&name) {
124 Some(linkage) => linkage,
126 ccx.sess().span_fatal(foreign_item.span,
127 "invalid linkage specified");
130 let llty2 = match ty.sty {
131 ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty),
133 ccx.sess().span_fatal(foreign_item.span,
134 "must have type `*T` or `*mut T`");
138 // Declare a symbol `foo` with the desired linkage.
139 let g1 = declare::declare_global(ccx, &ident[..], llty2);
140 llvm::SetLinkage(g1, linkage);
142 // Declare an internal global `extern_with_linkage_foo` which
143 // is initialized with the address of `foo`. If `foo` is
144 // discarded during linking (for example, if `foo` has weak
145 // linkage and there are no definitions), then
146 // `extern_with_linkage_foo` will instead be initialized to
148 let mut real_name = "_rust_extern_with_linkage_".to_string();
149 real_name.push_str(&ident);
150 let g2 = declare::define_global(ccx, &real_name[..], llty).unwrap_or_else(||{
151 ccx.sess().span_fatal(foreign_item.span,
152 &format!("symbol `{}` is already defined", ident))
154 llvm::SetLinkage(g2, llvm::InternalLinkage);
155 llvm::LLVMSetInitializer(g2, g1);
159 None => // Generate an external declaration.
160 declare::declare_global(ccx, &ident[..], llty),
164 // only use this for foreign function ABIs and glue, use `get_extern_rust_fn` for Rust functions
165 pub fn get_extern_fn(ccx: &CrateContext,
166 externs: &mut ExternMap,
172 match externs.get(name) {
173 Some(n) => return *n,
176 let f = declare::declare_fn(ccx, name, cc, ty, ty::FnConverging(output));
177 externs.insert(name.to_string(), f);
181 /// Registers a foreign function found in a library. Just adds a LLVM global.
182 pub fn register_foreign_item_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
183 abi: Abi, fty: Ty<'tcx>,
184 name: &str) -> ValueRef {
185 debug!("register_foreign_item_fn(abi={:?}, \
192 let cc = llvm_calling_convention(ccx, abi);
194 // Register the function as a C extern fn
195 let tys = foreign_types_for_fn_ty(ccx, fty);
197 // Make sure the calling convention is right for variadic functions
198 // (should've been caught if not in typeck)
199 if tys.fn_sig.variadic {
200 assert!(cc == llvm::CCallConv);
203 // Create the LLVM value for the C extern fn
204 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
206 let llfn = get_extern_fn(ccx, &mut *ccx.externs().borrow_mut(), name, cc, llfn_ty, fty);
207 add_argument_attributes(&tys, llfn);
211 /// Prepares a call to a native function. This requires adapting
212 /// from the Rust argument passing rules to the native rules.
216 /// - `callee_ty`: Rust type for the function we are calling
217 /// - `llfn`: the function pointer we are calling
218 /// - `llretptr`: where to store the return value of the function
219 /// - `llargs_rust`: a list of the argument values, prepared
220 /// as they would be if calling a Rust function
221 /// - `passed_arg_tys`: Rust type for the arguments. Normally we
222 /// can derive these from callee_ty but in the case of variadic
223 /// functions passed_arg_tys will include the Rust type of all
224 /// the arguments including the ones not specified in the fn's signature.
225 pub fn trans_native_call<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
229 llargs_rust: &[ValueRef],
230 passed_arg_tys: Vec<Ty<'tcx>>,
231 call_debug_loc: DebugLoc)
236 debug!("trans_native_call(callee_ty={:?}, \
240 ccx.tn().val_to_string(llfn),
241 ccx.tn().val_to_string(llretptr));
243 let (fn_abi, fn_sig) = match callee_ty.sty {
244 ty::TyBareFn(_, ref fn_ty) => (fn_ty.abi, &fn_ty.sig),
245 _ => ccx.sess().bug("trans_native_call called on non-function type")
247 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
248 let llsig = foreign_signature(ccx, &fn_sig, &passed_arg_tys[..]);
249 let fn_type = cabi::compute_abi_info(ccx,
254 let arg_tys: &[cabi::ArgType] = &fn_type.arg_tys;
256 let mut llargs_foreign = Vec::new();
258 // If the foreign ABI expects return value by pointer, supply the
259 // pointer that Rust gave us. Sometimes we have to bitcast
260 // because foreign fns return slightly different (but equivalent)
261 // views on the same type (e.g., i64 in place of {i32,i32}).
262 if fn_type.ret_ty.is_indirect() {
263 match fn_type.ret_ty.cast {
266 BitCast(bcx, llretptr, ty.ptr_to());
267 llargs_foreign.push(llcastedretptr);
270 llargs_foreign.push(llretptr);
276 for (i, arg_ty) in arg_tys.iter().enumerate() {
277 let mut llarg_rust = llargs_rust[i + offset];
279 if arg_ty.is_ignore() {
283 // Does Rust pass this argument by pointer?
284 let rust_indirect = type_of::arg_is_indirect(ccx, passed_arg_tys[i]);
286 debug!("argument {}, llarg_rust={}, rust_indirect={}, arg_ty={}",
288 ccx.tn().val_to_string(llarg_rust),
290 ccx.tn().type_to_string(arg_ty.ty));
292 // Ensure that we always have the Rust value indirectly,
293 // because it makes bitcasting easier.
297 type_of::type_of(ccx, passed_arg_tys[i]),
299 if type_is_fat_ptr(ccx.tcx(), passed_arg_tys[i]) {
300 Store(bcx, llargs_rust[i + offset], expr::get_dataptr(bcx, scratch));
301 Store(bcx, llargs_rust[i + offset + 1], expr::get_len(bcx, scratch));
304 base::store_ty(bcx, llarg_rust, scratch, passed_arg_tys[i]);
306 llarg_rust = scratch;
309 debug!("llarg_rust={} (after indirection)",
310 ccx.tn().val_to_string(llarg_rust));
312 // Check whether we need to do any casting
314 Some(ty) => llarg_rust = BitCast(bcx, llarg_rust, ty.ptr_to()),
318 debug!("llarg_rust={} (after casting)",
319 ccx.tn().val_to_string(llarg_rust));
321 // Finally, load the value if needed for the foreign ABI
322 let foreign_indirect = arg_ty.is_indirect();
323 let llarg_foreign = if foreign_indirect {
326 if passed_arg_tys[i].is_bool() {
327 let val = LoadRangeAssert(bcx, llarg_rust, 0, 2, llvm::False);
328 Trunc(bcx, val, Type::i1(bcx.ccx()))
330 Load(bcx, llarg_rust)
334 debug!("argument {}, llarg_foreign={}",
335 i, ccx.tn().val_to_string(llarg_foreign));
337 // fill padding with undef value
339 Some(ty) => llargs_foreign.push(C_undef(ty)),
342 llargs_foreign.push(llarg_foreign);
345 let cc = llvm_calling_convention(ccx, fn_abi);
347 // A function pointer is called without the declaration available, so we have to apply
348 // any attributes with ABI implications directly to the call instruction.
349 let mut attrs = llvm::AttrBuilder::new();
351 // Add attributes that are always applicable, independent of the concrete foreign ABI
352 if fn_type.ret_ty.is_indirect() {
353 let llret_sz = machine::llsize_of_real(ccx, fn_type.ret_ty.ty);
355 // The outptr can be noalias and nocapture because it's entirely
356 // invisible to the program. We also know it's nonnull as well
357 // as how many bytes we can dereference
358 attrs.arg(1, llvm::Attribute::NoAlias)
359 .arg(1, llvm::Attribute::NoCapture)
360 .arg(1, llvm::DereferenceableAttribute(llret_sz));
363 // Add attributes that depend on the concrete foreign ABI
364 let mut arg_idx = if fn_type.ret_ty.is_indirect() { 1 } else { 0 };
365 match fn_type.ret_ty.attr {
366 Some(attr) => { attrs.arg(arg_idx, attr); },
371 for arg_ty in &fn_type.arg_tys {
372 if arg_ty.is_ignore() {
376 if arg_ty.pad.is_some() { arg_idx += 1; }
378 if let Some(attr) = arg_ty.attr {
379 attrs.arg(arg_idx, attr);
385 let llforeign_retval = CallWithConv(bcx,
392 // If the function we just called does not use an outpointer,
393 // store the result into the rust outpointer. Cast the outpointer
394 // type to match because some ABIs will use a different type than
395 // the Rust type. e.g., a {u32,u32} struct could be returned as
397 if llsig.ret_def && !fn_type.ret_ty.is_indirect() {
398 let llrust_ret_ty = llsig.llret_ty;
399 let llforeign_ret_ty = match fn_type.ret_ty.cast {
401 None => fn_type.ret_ty.ty
404 debug!("llretptr={}", ccx.tn().val_to_string(llretptr));
405 debug!("llforeign_retval={}", ccx.tn().val_to_string(llforeign_retval));
406 debug!("llrust_ret_ty={}", ccx.tn().type_to_string(llrust_ret_ty));
407 debug!("llforeign_ret_ty={}", ccx.tn().type_to_string(llforeign_ret_ty));
409 if llrust_ret_ty == llforeign_ret_ty {
410 match fn_sig.output {
411 ty::FnConverging(result_ty) => {
412 base::store_ty(bcx, llforeign_retval, llretptr, result_ty)
414 ty::FnDiverging => {}
417 // The actual return type is a struct, but the ABI
418 // adaptation code has cast it into some scalar type. The
419 // code that follows is the only reliable way I have
420 // found to do a transform like i64 -> {i32,i32}.
421 // Basically we dump the data onto the stack then memcpy it.
423 // Other approaches I tried:
424 // - Casting rust ret pointer to the foreign type and using Store
425 // is (a) unsafe if size of foreign type > size of rust type and
426 // (b) runs afoul of strict aliasing rules, yielding invalid
427 // assembly under -O (specifically, the store gets removed).
428 // - Truncating foreign type to correct integral type and then
429 // bitcasting to the struct type yields invalid cast errors.
430 let llscratch = base::alloca(bcx, llforeign_ret_ty, "__cast");
431 Store(bcx, llforeign_retval, llscratch);
432 let llscratch_i8 = BitCast(bcx, llscratch, Type::i8(ccx).ptr_to());
433 let llretptr_i8 = BitCast(bcx, llretptr, Type::i8(ccx).ptr_to());
434 let llrust_size = machine::llsize_of_store(ccx, llrust_ret_ty);
435 let llforeign_align = machine::llalign_of_min(ccx, llforeign_ret_ty);
436 let llrust_align = machine::llalign_of_min(ccx, llrust_ret_ty);
437 let llalign = cmp::min(llforeign_align, llrust_align);
438 debug!("llrust_size={}", llrust_size);
439 base::call_memcpy(bcx, llretptr_i8, llscratch_i8,
440 C_uint(ccx, llrust_size), llalign as u32);
447 // feature gate SIMD types in FFI, since I (huonw) am not sure the
448 // ABIs are handled at all correctly.
449 fn gate_simd_ffi(tcx: &ty::ctxt, decl: &ast::FnDecl, ty: &ty::BareFnTy) {
450 if !tcx.sess.features.borrow().simd_ffi {
451 let check = |ast_ty: &ast::Ty, ty: ty::Ty| {
453 tcx.sess.span_err(ast_ty.span,
454 &format!("use of SIMD type `{}` in FFI is highly experimental and \
455 may result in invalid code",
456 pprust::ty_to_string(ast_ty)));
457 tcx.sess.fileline_help(ast_ty.span,
458 "add #![feature(simd_ffi)] to the crate attributes to enable");
462 for (input, ty) in decl.inputs.iter().zip(&sig.inputs) {
463 check(&*input.ty, *ty)
465 if let ast::Return(ref ty) = decl.output {
466 check(&**ty, sig.output.unwrap())
471 pub fn trans_foreign_mod(ccx: &CrateContext, foreign_mod: &ast::ForeignMod) {
472 let _icx = push_ctxt("foreign::trans_foreign_mod");
473 for foreign_item in &foreign_mod.items {
474 let lname = link_name(&**foreign_item);
476 if let ast::ForeignItemFn(ref decl, _) = foreign_item.node {
477 match foreign_mod.abi {
478 Rust | RustIntrinsic => {}
480 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
482 ty::TyBareFn(_, bft) => gate_simd_ffi(ccx.tcx(), &**decl, bft),
483 _ => ccx.tcx().sess.span_bug(foreign_item.span,
484 "foreign fn's sty isn't a bare_fn_ty?")
487 let llfn = register_foreign_item_fn(ccx, abi, ty, &lname);
488 attributes::from_fn_attrs(ccx, &foreign_item.attrs, llfn);
489 // Unlike for other items, we shouldn't call
490 // `base::update_linkage` here. Foreign items have
491 // special linkage requirements, which are handled
492 // inside `foreign::register_*`.
497 ccx.item_symbols().borrow_mut().insert(foreign_item.id,
502 ///////////////////////////////////////////////////////////////////////////
503 // Rust functions with foreign ABIs
505 // These are normal Rust functions defined with foreign ABIs. For
506 // now, and perhaps forever, we translate these using a "layer of
507 // indirection". That is, given a Rust declaration like:
509 // extern "C" fn foo(i: u32) -> u32 { ... }
511 // we will generate a function like:
515 // foo0(&r, NULL, i);
520 // void foo0(uint32_t *r, void *env, uint32_t i) { ... }
522 // Here the (internal) `foo0` function follows the Rust ABI as normal,
523 // where the `foo` function follows the C ABI. We rely on LLVM to
524 // inline the one into the other. Of course we could just generate the
525 // correct code in the first place, but this is much simpler.
527 pub fn decl_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
531 let tys = foreign_types_for_fn_ty(ccx, t);
532 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
533 let cconv = match t.sty {
534 ty::TyBareFn(_, ref fn_ty) => {
535 llvm_calling_convention(ccx, fn_ty.abi)
537 _ => panic!("expected bare fn in decl_rust_fn_with_foreign_abi")
539 let llfn = declare::declare_fn(ccx, name, cconv, llfn_ty,
540 ty::FnConverging(ccx.tcx().mk_nil()));
541 add_argument_attributes(&tys, llfn);
542 debug!("decl_rust_fn_with_foreign_abi(llfn_ty={}, llfn={})",
543 ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
547 pub fn register_rust_fn_with_foreign_abi(ccx: &CrateContext,
550 node_id: ast::NodeId)
552 let _icx = push_ctxt("foreign::register_foreign_fn");
554 let tys = foreign_types_for_id(ccx, node_id);
555 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
556 let t = ccx.tcx().node_id_to_type(node_id);
557 let cconv = match t.sty {
558 ty::TyBareFn(_, ref fn_ty) => {
559 llvm_calling_convention(ccx, fn_ty.abi)
561 _ => panic!("expected bare fn in register_rust_fn_with_foreign_abi")
563 let llfn = base::register_fn_llvmty(ccx, sp, sym, node_id, cconv, llfn_ty);
564 add_argument_attributes(&tys, llfn);
565 debug!("register_rust_fn_with_foreign_abi(node_id={}, llfn_ty={}, llfn={})",
566 node_id, ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
570 pub fn trans_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
573 attrs: &[ast::Attribute],
575 param_substs: &'tcx Substs<'tcx>,
577 hash: Option<&str>) {
578 let _icx = push_ctxt("foreign::build_foreign_fn");
580 let fnty = ccx.tcx().node_id_to_type(id);
581 let mty = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &fnty);
582 let tys = foreign_types_for_fn_ty(ccx, mty);
584 unsafe { // unsafe because we call LLVM operations
585 // Build up the Rust function (`foo0` above).
586 let llrustfn = build_rust_fn(ccx, decl, body, param_substs, attrs, id, hash);
588 // Build up the foreign wrapper (`foo` above).
589 return build_wrap_fn(ccx, llrustfn, llwrapfn, &tys, mty);
592 fn build_rust_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
595 param_substs: &'tcx Substs<'tcx>,
596 attrs: &[ast::Attribute],
601 let _icx = push_ctxt("foreign::foreign::build_rust_fn");
603 let t = tcx.node_id_to_type(id);
604 let t = monomorphize::apply_param_substs(tcx, param_substs, &t);
606 let ps = ccx.tcx().map.with_path(id, |path| {
607 let abi = Some(ast_map::PathName(special_idents::clownshoe_abi.name));
608 link::mangle(path.chain(abi), hash)
611 // Compute the type that the function would have if it were just a
612 // normal Rust function. This will be the type of the wrappee fn.
614 ty::TyBareFn(_, ref f) => {
615 assert!(f.abi != Rust && f.abi != RustIntrinsic);
618 ccx.sess().bug(&format!("build_rust_fn: extern fn {} has ty {:?}, \
619 expected a bare fn ty",
620 ccx.tcx().map.path_to_string(id),
625 debug!("build_rust_fn: path={} id={} t={:?}",
626 ccx.tcx().map.path_to_string(id),
629 let llfn = declare::define_internal_rust_fn(ccx, &ps, t);
630 attributes::from_fn_attrs(ccx, attrs, llfn);
631 base::trans_fn(ccx, decl, body, llfn, param_substs, id, &[]);
635 unsafe fn build_wrap_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
638 tys: &ForeignTypes<'tcx>,
640 let _icx = push_ctxt(
641 "foreign::trans_rust_fn_with_foreign_abi::build_wrap_fn");
643 debug!("build_wrap_fn(llrustfn={}, llwrapfn={}, t={:?})",
644 ccx.tn().val_to_string(llrustfn),
645 ccx.tn().val_to_string(llwrapfn),
648 // Avoid all the Rust generation stuff and just generate raw
651 // We want to generate code like this:
655 // foo0(&r, NULL, i);
659 if llvm::LLVMCountBasicBlocks(llwrapfn) != 0 {
660 ccx.sess().bug("wrapping a function inside non-empty wrapper, most likely cause is \
661 multiple functions being wrapped");
664 let ptr = "the block\0".as_ptr();
665 let the_block = llvm::LLVMAppendBasicBlockInContext(ccx.llcx(), llwrapfn,
668 let builder = ccx.builder();
669 builder.position_at_end(the_block);
671 // Array for the arguments we will pass to the rust function.
672 let mut llrust_args = Vec::new();
673 let mut next_foreign_arg_counter: c_uint = 0;
674 let mut next_foreign_arg = |pad: bool| -> c_uint {
675 next_foreign_arg_counter += if pad {
680 next_foreign_arg_counter - 1
683 // If there is an out pointer on the foreign function
684 let foreign_outptr = {
685 if tys.fn_ty.ret_ty.is_indirect() {
686 Some(get_param(llwrapfn, next_foreign_arg(false)))
692 let rustfn_ty = Type::from_ref(llvm::LLVMTypeOf(llrustfn)).element_type();
693 let mut rust_param_tys = rustfn_ty.func_params().into_iter();
694 // Push Rust return pointer, using null if it will be unused.
695 let rust_uses_outptr = match tys.fn_sig.output {
696 ty::FnConverging(ret_ty) => type_of::return_uses_outptr(ccx, ret_ty),
697 ty::FnDiverging => false
699 let return_alloca: Option<ValueRef>;
700 let llrust_ret_ty = if rust_uses_outptr {
701 rust_param_tys.next().expect("Missing return type!").element_type()
703 rustfn_ty.return_type()
705 if rust_uses_outptr {
706 // Rust expects to use an outpointer. If the foreign fn
707 // also uses an outpointer, we can reuse it, but the types
708 // may vary, so cast first to the Rust type. If the
709 // foreign fn does NOT use an outpointer, we will have to
710 // alloca some scratch space on the stack.
711 match foreign_outptr {
712 Some(llforeign_outptr) => {
713 debug!("out pointer, foreign={}",
714 ccx.tn().val_to_string(llforeign_outptr));
716 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
717 debug!("out pointer, foreign={} (casted)",
718 ccx.tn().val_to_string(llrust_retptr));
719 llrust_args.push(llrust_retptr);
720 return_alloca = None;
724 let slot = builder.alloca(llrust_ret_ty, "return_alloca");
725 debug!("out pointer, \
729 ccx.tn().val_to_string(slot),
730 ccx.tn().type_to_string(llrust_ret_ty),
732 llrust_args.push(slot);
733 return_alloca = Some(slot);
737 // Rust does not expect an outpointer. If the foreign fn
738 // does use an outpointer, then we will do a store of the
739 // value that the Rust fn returns.
740 return_alloca = None;
743 // Build up the arguments to the call to the rust function.
744 // Careful to adapt for cases where the native convention uses
745 // a pointer and Rust does not or vice versa.
746 for i in 0..tys.fn_sig.inputs.len() {
747 let rust_ty = tys.fn_sig.inputs[i];
748 let rust_indirect = type_of::arg_is_indirect(ccx, rust_ty);
749 let llty = rust_param_tys.next().expect("Not enough parameter types!");
750 let llrust_ty = if rust_indirect {
755 let llforeign_arg_ty = tys.fn_ty.arg_tys[i];
756 let foreign_indirect = llforeign_arg_ty.is_indirect();
758 if llforeign_arg_ty.is_ignore() {
759 debug!("skipping ignored arg #{}", i);
760 llrust_args.push(C_undef(llrust_ty));
765 let foreign_index = next_foreign_arg(llforeign_arg_ty.pad.is_some());
766 let mut llforeign_arg = get_param(llwrapfn, foreign_index);
768 debug!("llforeign_arg {}{}: {}", "#",
769 i, ccx.tn().val_to_string(llforeign_arg));
770 debug!("rust_indirect = {}, foreign_indirect = {}",
771 rust_indirect, foreign_indirect);
773 // Ensure that the foreign argument is indirect (by
774 // pointer). It makes adapting types easier, since we can
775 // always just bitcast pointers.
776 if !foreign_indirect {
777 llforeign_arg = if rust_ty.is_bool() {
778 let lltemp = builder.alloca(Type::bool(ccx), "");
779 builder.store(builder.zext(llforeign_arg, Type::bool(ccx)), lltemp);
782 let lltemp = builder.alloca(val_ty(llforeign_arg), "");
783 builder.store(llforeign_arg, lltemp);
788 // If the types in the ABI and the Rust types don't match,
789 // bitcast the llforeign_arg pointer so it matches the types
791 if llforeign_arg_ty.cast.is_some() && !type_is_fat_ptr(ccx.tcx(), rust_ty){
792 assert!(!foreign_indirect);
793 llforeign_arg = builder.bitcast(llforeign_arg, llrust_ty.ptr_to());
796 let llrust_arg = if rust_indirect || type_is_fat_ptr(ccx.tcx(), rust_ty) {
799 if rust_ty.is_bool() {
800 let tmp = builder.load_range_assert(llforeign_arg, 0, 2, llvm::False);
801 builder.trunc(tmp, Type::i1(ccx))
802 } else if type_of::type_of(ccx, rust_ty).is_aggregate() {
803 // We want to pass small aggregates as immediate values, but using an aggregate
804 // LLVM type for this leads to bad optimizations, so its arg type is an
805 // appropriately sized integer and we have to convert it
806 let tmp = builder.bitcast(llforeign_arg,
807 type_of::arg_type_of(ccx, rust_ty).ptr_to());
808 let load = builder.load(tmp);
809 llvm::LLVMSetAlignment(load, type_of::align_of(ccx, rust_ty));
812 builder.load(llforeign_arg)
816 debug!("llrust_arg {}{}: {}", "#",
817 i, ccx.tn().val_to_string(llrust_arg));
818 if type_is_fat_ptr(ccx.tcx(), rust_ty) {
819 let next_llrust_ty = rust_param_tys.next().expect("Not enough parameter types!");
820 llrust_args.push(builder.load(builder.bitcast(builder.gepi(
821 llrust_arg, &[0, abi::FAT_PTR_ADDR]), llrust_ty.ptr_to())));
822 llrust_args.push(builder.load(builder.bitcast(builder.gepi(
823 llrust_arg, &[0, abi::FAT_PTR_EXTRA]), next_llrust_ty.ptr_to())));
825 llrust_args.push(llrust_arg);
829 // Perform the call itself
830 debug!("calling llrustfn = {}, t = {:?}",
831 ccx.tn().val_to_string(llrustfn), t);
832 let attributes = attributes::from_fn_type(ccx, t);
833 let llrust_ret_val = builder.call(llrustfn, &llrust_args, Some(attributes));
835 // Get the return value where the foreign fn expects it.
836 let llforeign_ret_ty = match tys.fn_ty.ret_ty.cast {
838 None => tys.fn_ty.ret_ty.ty
840 match foreign_outptr {
841 None if !tys.llsig.ret_def => {
842 // Function returns `()` or `bot`, which in Rust is the LLVM
843 // type "{}" but in foreign ABIs is "Void".
847 None if rust_uses_outptr => {
848 // Rust uses an outpointer, but the foreign ABI does not. Load.
849 let llrust_outptr = return_alloca.unwrap();
850 let llforeign_outptr_casted =
851 builder.bitcast(llrust_outptr, llforeign_ret_ty.ptr_to());
852 let llforeign_retval = builder.load(llforeign_outptr_casted);
853 builder.ret(llforeign_retval);
856 None if llforeign_ret_ty != llrust_ret_ty => {
857 // Neither ABI uses an outpointer, but the types don't
858 // quite match. Must cast. Probably we should try and
859 // examine the types and use a concrete llvm cast, but
860 // right now we just use a temp memory location and
861 // bitcast the pointer, which is the same thing the
862 // old wrappers used to do.
863 let lltemp = builder.alloca(llforeign_ret_ty, "");
864 let lltemp_casted = builder.bitcast(lltemp, llrust_ret_ty.ptr_to());
865 builder.store(llrust_ret_val, lltemp_casted);
866 let llforeign_retval = builder.load(lltemp);
867 builder.ret(llforeign_retval);
871 // Neither ABI uses an outpointer, and the types
872 // match. Easy peasy.
873 builder.ret(llrust_ret_val);
876 Some(llforeign_outptr) if !rust_uses_outptr => {
877 // Foreign ABI requires an out pointer, but Rust doesn't.
878 // Store Rust return value.
879 let llforeign_outptr_casted =
880 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
881 builder.store(llrust_ret_val, llforeign_outptr_casted);
886 // Both ABIs use outpointers. Easy peasy.
893 ///////////////////////////////////////////////////////////////////////////
894 // General ABI Support
896 // This code is kind of a confused mess and needs to be reworked given
897 // the massive simplifications that have occurred.
899 pub fn link_name(i: &ast::ForeignItem) -> InternedString {
900 match attr::first_attr_value_str_by_name(&i.attrs, "link_name") {
901 Some(ln) => ln.clone(),
902 None => match weak_lang_items::link_name(&i.attrs) {
904 None => i.ident.name.as_str(),
909 /// The ForeignSignature is the LLVM types of the arguments/return type of a function. Note that
910 /// these LLVM types are not quite the same as the LLVM types would be for a native Rust function
911 /// because foreign functions just plain ignore modes. They also don't pass aggregate values by
912 /// pointer like we do.
913 fn foreign_signature<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
914 fn_sig: &ty::FnSig<'tcx>,
915 arg_tys: &[Ty<'tcx>])
917 let llarg_tys = arg_tys.iter().map(|&arg| foreign_arg_type_of(ccx, arg)).collect();
918 let (llret_ty, ret_def) = match fn_sig.output {
919 ty::FnConverging(ret_ty) =>
920 (type_of::foreign_arg_type_of(ccx, ret_ty), !return_type_is_void(ccx, ret_ty)),
922 (Type::nil(ccx), false)
925 llarg_tys: llarg_tys,
931 fn foreign_types_for_id<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
932 id: ast::NodeId) -> ForeignTypes<'tcx> {
933 foreign_types_for_fn_ty(ccx, ccx.tcx().node_id_to_type(id))
936 fn foreign_types_for_fn_ty<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
937 ty: Ty<'tcx>) -> ForeignTypes<'tcx> {
938 let fn_sig = match ty.sty {
939 ty::TyBareFn(_, ref fn_ty) => &fn_ty.sig,
940 _ => ccx.sess().bug("foreign_types_for_fn_ty called on non-function type")
942 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
943 let llsig = foreign_signature(ccx, &fn_sig, &fn_sig.inputs);
944 let fn_ty = cabi::compute_abi_info(ccx,
948 debug!("foreign_types_for_fn_ty(\
954 ccx.tn().types_to_str(&llsig.llarg_tys),
955 ccx.tn().type_to_string(llsig.llret_ty),
956 ccx.tn().types_to_str(&fn_ty.arg_tys.iter().map(|t| t.ty).collect::<Vec<_>>()),
957 ccx.tn().type_to_string(fn_ty.ret_ty.ty),
967 fn lltype_for_fn_from_foreign_types(ccx: &CrateContext, tys: &ForeignTypes) -> Type {
968 let mut llargument_tys = Vec::new();
970 let ret_ty = tys.fn_ty.ret_ty;
971 let llreturn_ty = if ret_ty.is_indirect() {
972 llargument_tys.push(ret_ty.ty.ptr_to());
981 for &arg_ty in &tys.fn_ty.arg_tys {
982 if arg_ty.is_ignore() {
987 Some(ty) => llargument_tys.push(ty),
991 let llarg_ty = if arg_ty.is_indirect() {
1000 llargument_tys.push(llarg_ty);
1003 if tys.fn_sig.variadic {
1004 Type::variadic_func(&llargument_tys, &llreturn_ty)
1006 Type::func(&llargument_tys[..], &llreturn_ty)
1010 pub fn lltype_for_foreign_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
1011 ty: Ty<'tcx>) -> Type {
1012 lltype_for_fn_from_foreign_types(ccx, &foreign_types_for_fn_ty(ccx, ty))
1015 fn add_argument_attributes(tys: &ForeignTypes,
1017 let mut i = if tys.fn_ty.ret_ty.is_indirect() {
1023 match tys.fn_ty.ret_ty.attr {
1024 Some(attr) => unsafe {
1025 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);
1032 for &arg_ty in &tys.fn_ty.arg_tys {
1033 if arg_ty.is_ignore() {
1037 if arg_ty.pad.is_some() { i += 1; }
1040 Some(attr) => unsafe {
1041 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);