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;
16 use trans::attributes;
17 use trans::base::{llvm_linkage_by_name, push_ctxt};
22 use trans::debuginfo::DebugLoc;
26 use trans::monomorphize;
27 use trans::type_::Type;
28 use trans::type_of::*;
31 use middle::ty::{self, Ty};
32 use middle::subst::Substs;
39 use syntax::codemap::Span;
40 use syntax::parse::token::{InternedString, special_idents};
43 use rustc_front::print::pprust;
46 ///////////////////////////////////////////////////////////////////////////
49 struct ForeignTypes<'tcx> {
50 /// Rust signature of the function
51 fn_sig: ty::FnSig<'tcx>,
53 /// Adapter object for handling native ABI rules (trust me, you
54 /// don't want to know)
57 /// LLVM types that will appear on the foreign function
61 struct LlvmSignature {
62 // LLVM versions of the types of this function's arguments.
63 llarg_tys: Vec<Type> ,
65 // LLVM version of the type that this function returns. Note that
66 // this *may not be* the declared return type of the foreign
67 // function, because the foreign function may opt to return via an
71 /// True if there is a return value (not bottom, not unit)
76 ///////////////////////////////////////////////////////////////////////////
77 // Calls to external functions
79 pub fn llvm_calling_convention(ccx: &CrateContext,
80 abi: Abi) -> CallConv {
81 use syntax::abi::Abi::*;
82 match ccx.sess().target.target.adjust_abi(abi) {
84 // Intrinsics are emitted at the call site
85 ccx.sess().bug("asked to register intrinsic fn");
87 PlatformIntrinsic => {
88 // Intrinsics are emitted at the call site
89 ccx.sess().bug("asked to register platform intrinsic fn");
93 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
94 ccx.sess().unimpl("foreign functions with Rust ABI");
98 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
99 ccx.sess().unimpl("foreign functions with RustCall ABI");
102 // It's the ABI's job to select this, not us.
103 System => ccx.sess().bug("system abi should be selected elsewhere"),
105 Stdcall => llvm::X86StdcallCallConv,
106 Fastcall => llvm::X86FastcallCallConv,
107 Vectorcall => llvm::X86_VectorCall,
108 C => llvm::CCallConv,
109 Win64 => llvm::X86_64_Win64,
111 // These API constants ought to be more specific...
112 Cdecl => llvm::CCallConv,
113 Aapcs => llvm::CCallConv,
117 pub fn register_static(ccx: &CrateContext,
118 foreign_item: &hir::ForeignItem) -> ValueRef {
119 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
120 let llty = type_of::type_of(ccx, ty);
122 let ident = link_name(foreign_item);
123 match attr::first_attr_value_str_by_name(&foreign_item.attrs,
125 // If this is a static with a linkage specified, then we need to handle
126 // it a little specially. The typesystem prevents things like &T and
127 // extern "C" fn() from being non-null, so we can't just declare a
128 // static and call it a day. Some linkages (like weak) will make it such
129 // that the static actually has a null value.
131 let linkage = match llvm_linkage_by_name(&name) {
132 Some(linkage) => linkage,
134 ccx.sess().span_fatal(foreign_item.span,
135 "invalid linkage specified");
138 let llty2 = match ty.sty {
139 ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty),
141 ccx.sess().span_fatal(foreign_item.span,
142 "must have type `*T` or `*mut T`");
146 // Declare a symbol `foo` with the desired linkage.
147 let g1 = declare::declare_global(ccx, &ident[..], llty2);
148 llvm::SetLinkage(g1, linkage);
150 // Declare an internal global `extern_with_linkage_foo` which
151 // is initialized with the address of `foo`. If `foo` is
152 // discarded during linking (for example, if `foo` has weak
153 // linkage and there are no definitions), then
154 // `extern_with_linkage_foo` will instead be initialized to
156 let mut real_name = "_rust_extern_with_linkage_".to_string();
157 real_name.push_str(&ident);
158 let g2 = declare::define_global(ccx, &real_name[..], llty).unwrap_or_else(||{
159 ccx.sess().span_fatal(foreign_item.span,
160 &format!("symbol `{}` is already defined", ident))
162 llvm::SetLinkage(g2, llvm::InternalLinkage);
163 llvm::LLVMSetInitializer(g2, g1);
167 None => // Generate an external declaration.
168 declare::declare_global(ccx, &ident[..], llty),
172 // only use this for foreign function ABIs and glue, use `get_extern_rust_fn` for Rust functions
173 pub fn get_extern_fn(ccx: &CrateContext,
174 externs: &mut ExternMap,
180 match externs.get(name) {
181 Some(n) => return *n,
184 let f = declare::declare_fn(ccx, name, cc, ty, ty::FnConverging(output));
185 externs.insert(name.to_string(), f);
189 /// Registers a foreign function found in a library. Just adds a LLVM global.
190 pub fn register_foreign_item_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
191 abi: Abi, fty: Ty<'tcx>,
193 attrs: &[ast::Attribute])-> ValueRef {
194 debug!("register_foreign_item_fn(abi={:?}, \
201 let cc = llvm_calling_convention(ccx, abi);
203 // Register the function as a C extern fn
204 let tys = foreign_types_for_fn_ty(ccx, fty);
206 // Make sure the calling convention is right for variadic functions
207 // (should've been caught if not in typeck)
208 if tys.fn_sig.variadic {
209 assert!(cc == llvm::CCallConv);
212 // Create the LLVM value for the C extern fn
213 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
215 let llfn = get_extern_fn(ccx, &mut *ccx.externs().borrow_mut(), name, cc, llfn_ty, fty);
216 attributes::unwind(llfn, false);
217 add_argument_attributes(&tys, llfn);
218 attributes::from_fn_attrs(ccx, attrs, llfn);
222 /// Prepares a call to a native function. This requires adapting
223 /// from the Rust argument passing rules to the native rules.
227 /// - `callee_ty`: Rust type for the function we are calling
228 /// - `llfn`: the function pointer we are calling
229 /// - `llretptr`: where to store the return value of the function
230 /// - `llargs_rust`: a list of the argument values, prepared
231 /// as they would be if calling a Rust function
232 /// - `passed_arg_tys`: Rust type for the arguments. Normally we
233 /// can derive these from callee_ty but in the case of variadic
234 /// functions passed_arg_tys will include the Rust type of all
235 /// the arguments including the ones not specified in the fn's signature.
236 pub fn trans_native_call<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
240 llargs_rust: &[ValueRef],
241 passed_arg_tys: Vec<Ty<'tcx>>,
242 call_debug_loc: DebugLoc)
247 debug!("trans_native_call(callee_ty={:?}, \
251 ccx.tn().val_to_string(llfn),
252 ccx.tn().val_to_string(llretptr));
254 let (fn_abi, fn_sig) = match callee_ty.sty {
255 ty::TyBareFn(_, ref fn_ty) => (fn_ty.abi, &fn_ty.sig),
256 _ => ccx.sess().bug("trans_native_call called on non-function type")
258 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
259 let fn_sig = infer::normalize_associated_type(ccx.tcx(), &fn_sig);
260 let llsig = foreign_signature(ccx, &fn_sig, &passed_arg_tys[..]);
261 let fn_type = cabi::compute_abi_info(ccx,
266 let arg_tys: &[cabi::ArgType] = &fn_type.arg_tys;
268 let mut llargs_foreign = Vec::new();
270 // If the foreign ABI expects return value by pointer, supply the
271 // pointer that Rust gave us. Sometimes we have to bitcast
272 // because foreign fns return slightly different (but equivalent)
273 // views on the same type (e.g., i64 in place of {i32,i32}).
274 if fn_type.ret_ty.is_indirect() {
275 match fn_type.ret_ty.cast {
278 BitCast(bcx, llretptr, ty.ptr_to());
279 llargs_foreign.push(llcastedretptr);
282 llargs_foreign.push(llretptr);
288 for (i, arg_ty) in arg_tys.iter().enumerate() {
289 let mut llarg_rust = llargs_rust[i + offset];
291 if arg_ty.is_ignore() {
295 // Does Rust pass this argument by pointer?
296 let rust_indirect = type_of::arg_is_indirect(ccx, passed_arg_tys[i]);
298 debug!("argument {}, llarg_rust={}, rust_indirect={}, arg_ty={}",
300 ccx.tn().val_to_string(llarg_rust),
302 ccx.tn().type_to_string(arg_ty.ty));
304 // Ensure that we always have the Rust value indirectly,
305 // because it makes bitcasting easier.
307 let scratch = base::alloc_ty(bcx, passed_arg_tys[i], "__arg");
308 if type_is_fat_ptr(ccx.tcx(), passed_arg_tys[i]) {
309 Store(bcx, llargs_rust[i + offset], expr::get_dataptr(bcx, scratch));
310 Store(bcx, llargs_rust[i + offset + 1], expr::get_meta(bcx, scratch));
313 base::store_ty(bcx, llarg_rust, scratch, passed_arg_tys[i]);
315 llarg_rust = scratch;
318 debug!("llarg_rust={} (after indirection)",
319 ccx.tn().val_to_string(llarg_rust));
321 // Check whether we need to do any casting
323 Some(ty) => llarg_rust = BitCast(bcx, llarg_rust, ty.ptr_to()),
327 debug!("llarg_rust={} (after casting)",
328 ccx.tn().val_to_string(llarg_rust));
330 // Finally, load the value if needed for the foreign ABI
331 let foreign_indirect = arg_ty.is_indirect();
332 let llarg_foreign = if foreign_indirect {
335 if passed_arg_tys[i].is_bool() {
336 let val = LoadRangeAssert(bcx, llarg_rust, 0, 2, llvm::False);
337 Trunc(bcx, val, Type::i1(bcx.ccx()))
339 Load(bcx, llarg_rust)
343 debug!("argument {}, llarg_foreign={}",
344 i, ccx.tn().val_to_string(llarg_foreign));
346 // fill padding with undef value
348 Some(ty) => llargs_foreign.push(C_undef(ty)),
351 llargs_foreign.push(llarg_foreign);
354 let cc = llvm_calling_convention(ccx, fn_abi);
356 // A function pointer is called without the declaration available, so we have to apply
357 // any attributes with ABI implications directly to the call instruction.
358 let mut attrs = llvm::AttrBuilder::new();
360 // Add attributes that are always applicable, independent of the concrete foreign ABI
361 if fn_type.ret_ty.is_indirect() {
362 let llret_sz = machine::llsize_of_real(ccx, fn_type.ret_ty.ty);
364 // The outptr can be noalias and nocapture because it's entirely
365 // invisible to the program. We also know it's nonnull as well
366 // as how many bytes we can dereference
367 attrs.arg(1, llvm::Attribute::NoAlias)
368 .arg(1, llvm::Attribute::NoCapture)
369 .arg(1, llvm::DereferenceableAttribute(llret_sz));
372 // Add attributes that depend on the concrete foreign ABI
373 let mut arg_idx = if fn_type.ret_ty.is_indirect() { 1 } else { 0 };
374 match fn_type.ret_ty.attr {
375 Some(attr) => { attrs.arg(arg_idx, attr); },
380 for arg_ty in &fn_type.arg_tys {
381 if arg_ty.is_ignore() {
385 if arg_ty.pad.is_some() { arg_idx += 1; }
387 if let Some(attr) = arg_ty.attr {
388 attrs.arg(arg_idx, attr);
394 let llforeign_retval = CallWithConv(bcx,
401 // If the function we just called does not use an outpointer,
402 // store the result into the rust outpointer. Cast the outpointer
403 // type to match because some ABIs will use a different type than
404 // the Rust type. e.g., a {u32,u32} struct could be returned as
406 if llsig.ret_def && !fn_type.ret_ty.is_indirect() {
407 let llrust_ret_ty = llsig.llret_ty;
408 let llforeign_ret_ty = match fn_type.ret_ty.cast {
410 None => fn_type.ret_ty.ty
413 debug!("llretptr={}", ccx.tn().val_to_string(llretptr));
414 debug!("llforeign_retval={}", ccx.tn().val_to_string(llforeign_retval));
415 debug!("llrust_ret_ty={}", ccx.tn().type_to_string(llrust_ret_ty));
416 debug!("llforeign_ret_ty={}", ccx.tn().type_to_string(llforeign_ret_ty));
418 if llrust_ret_ty == llforeign_ret_ty {
419 match fn_sig.output {
420 ty::FnConverging(result_ty) => {
421 base::store_ty(bcx, llforeign_retval, llretptr, result_ty)
423 ty::FnDiverging => {}
426 // The actual return type is a struct, but the ABI
427 // adaptation code has cast it into some scalar type. The
428 // code that follows is the only reliable way I have
429 // found to do a transform like i64 -> {i32,i32}.
430 // Basically we dump the data onto the stack then memcpy it.
432 // Other approaches I tried:
433 // - Casting rust ret pointer to the foreign type and using Store
434 // is (a) unsafe if size of foreign type > size of rust type and
435 // (b) runs afoul of strict aliasing rules, yielding invalid
436 // assembly under -O (specifically, the store gets removed).
437 // - Truncating foreign type to correct integral type and then
438 // bitcasting to the struct type yields invalid cast errors.
439 let llscratch = base::alloca(bcx, llforeign_ret_ty, "__cast");
440 base::call_lifetime_start(bcx, llscratch);
441 Store(bcx, llforeign_retval, llscratch);
442 let llscratch_i8 = BitCast(bcx, llscratch, Type::i8(ccx).ptr_to());
443 let llretptr_i8 = BitCast(bcx, llretptr, Type::i8(ccx).ptr_to());
444 let llrust_size = machine::llsize_of_store(ccx, llrust_ret_ty);
445 let llforeign_align = machine::llalign_of_min(ccx, llforeign_ret_ty);
446 let llrust_align = machine::llalign_of_min(ccx, llrust_ret_ty);
447 let llalign = cmp::min(llforeign_align, llrust_align);
448 debug!("llrust_size={}", llrust_size);
449 base::call_memcpy(bcx, llretptr_i8, llscratch_i8,
450 C_uint(ccx, llrust_size), llalign as u32);
451 base::call_lifetime_end(bcx, llscratch);
458 // feature gate SIMD types in FFI, since I (huonw) am not sure the
459 // ABIs are handled at all correctly.
460 fn gate_simd_ffi(tcx: &ty::ctxt, decl: &hir::FnDecl, ty: &ty::BareFnTy) {
461 if !tcx.sess.features.borrow().simd_ffi {
462 let check = |ast_ty: &hir::Ty, ty: ty::Ty| {
464 tcx.sess.struct_span_err(ast_ty.span,
465 &format!("use of SIMD type `{}` in FFI is highly experimental and \
466 may result in invalid code",
467 pprust::ty_to_string(ast_ty)))
468 .fileline_help(ast_ty.span,
469 "add #![feature(simd_ffi)] to the crate attributes to enable")
474 for (input, ty) in decl.inputs.iter().zip(&sig.inputs) {
475 check(&input.ty, *ty)
477 if let hir::Return(ref ty) = decl.output {
478 check(&ty, sig.output.unwrap())
483 pub fn trans_foreign_mod(ccx: &CrateContext, foreign_mod: &hir::ForeignMod) {
484 let _icx = push_ctxt("foreign::trans_foreign_mod");
485 for foreign_item in &foreign_mod.items {
486 let lname = link_name(foreign_item);
488 if let hir::ForeignItemFn(ref decl, _) = foreign_item.node {
489 match foreign_mod.abi {
490 Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic => {}
492 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
494 ty::TyBareFn(_, bft) => gate_simd_ffi(ccx.tcx(), &decl, bft),
495 _ => ccx.tcx().sess.span_bug(foreign_item.span,
496 "foreign fn's sty isn't a bare_fn_ty?")
499 register_foreign_item_fn(ccx, abi, ty, &lname, &foreign_item.attrs);
500 // Unlike for other items, we shouldn't call
501 // `base::update_linkage` here. Foreign items have
502 // special linkage requirements, which are handled
503 // inside `foreign::register_*`.
508 ccx.item_symbols().borrow_mut().insert(foreign_item.id,
513 ///////////////////////////////////////////////////////////////////////////
514 // Rust functions with foreign ABIs
516 // These are normal Rust functions defined with foreign ABIs. For
517 // now, and perhaps forever, we translate these using a "layer of
518 // indirection". That is, given a Rust declaration like:
520 // extern "C" fn foo(i: u32) -> u32 { ... }
522 // we will generate a function like:
526 // foo0(&r, NULL, i);
531 // void foo0(uint32_t *r, void *env, uint32_t i) { ... }
533 // Here the (internal) `foo0` function follows the Rust ABI as normal,
534 // where the `foo` function follows the C ABI. We rely on LLVM to
535 // inline the one into the other. Of course we could just generate the
536 // correct code in the first place, but this is much simpler.
538 pub fn decl_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
542 let tys = foreign_types_for_fn_ty(ccx, t);
543 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
544 let cconv = match t.sty {
545 ty::TyBareFn(_, ref fn_ty) => {
546 llvm_calling_convention(ccx, fn_ty.abi)
548 _ => panic!("expected bare fn in decl_rust_fn_with_foreign_abi")
550 let llfn = declare::declare_fn(ccx, name, cconv, llfn_ty,
551 ty::FnConverging(ccx.tcx().mk_nil()));
552 add_argument_attributes(&tys, llfn);
553 debug!("decl_rust_fn_with_foreign_abi(llfn_ty={}, llfn={})",
554 ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
558 pub fn register_rust_fn_with_foreign_abi(ccx: &CrateContext,
561 node_id: ast::NodeId)
563 let _icx = push_ctxt("foreign::register_foreign_fn");
565 let t = ccx.tcx().node_id_to_type(node_id);
566 let cconv = match t.sty {
567 ty::TyBareFn(_, ref fn_ty) => {
568 llvm_calling_convention(ccx, fn_ty.abi)
570 _ => panic!("expected bare fn in register_rust_fn_with_foreign_abi")
572 let tys = foreign_types_for_fn_ty(ccx, t);
573 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
574 let llfn = base::register_fn_llvmty(ccx, sp, sym, node_id, cconv, llfn_ty);
575 add_argument_attributes(&tys, llfn);
576 debug!("register_rust_fn_with_foreign_abi(node_id={}, llfn_ty={}, llfn={})",
577 node_id, ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
581 pub fn trans_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
584 attrs: &[ast::Attribute],
586 param_substs: &'tcx Substs<'tcx>,
588 hash: Option<&str>) {
589 let _icx = push_ctxt("foreign::build_foreign_fn");
591 let fnty = ccx.tcx().node_id_to_type(id);
592 let mty = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &fnty);
593 let tys = foreign_types_for_fn_ty(ccx, mty);
595 unsafe { // unsafe because we call LLVM operations
596 // Build up the Rust function (`foo0` above).
597 let llrustfn = build_rust_fn(ccx, decl, body, param_substs, attrs, id, hash);
599 // Build up the foreign wrapper (`foo` above).
600 return build_wrap_fn(ccx, llrustfn, llwrapfn, &tys, mty);
603 fn build_rust_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
606 param_substs: &'tcx Substs<'tcx>,
607 attrs: &[ast::Attribute],
612 let _icx = push_ctxt("foreign::foreign::build_rust_fn");
614 let t = tcx.node_id_to_type(id);
615 let t = monomorphize::apply_param_substs(tcx, param_substs, &t);
618 tcx.map.def_path_from_id(id)
620 .map(|e| e.data.as_interned_str())
621 .chain(once(special_idents::clownshoe_abi.name.as_str()));
622 let ps = link::mangle(path, hash);
624 // Compute the type that the function would have if it were just a
625 // normal Rust function. This will be the type of the wrappee fn.
627 ty::TyBareFn(_, ref f) => {
628 assert!(f.abi != Abi::Rust);
629 assert!(f.abi != Abi::RustIntrinsic);
630 assert!(f.abi != Abi::PlatformIntrinsic);
633 ccx.sess().bug(&format!("build_rust_fn: extern fn {} has ty {:?}, \
634 expected a bare fn ty",
635 ccx.tcx().map.path_to_string(id),
640 debug!("build_rust_fn: path={} id={} t={:?}",
641 ccx.tcx().map.path_to_string(id),
644 let llfn = declare::define_internal_rust_fn(ccx, &ps, t);
645 attributes::from_fn_attrs(ccx, attrs, llfn);
646 base::trans_fn(ccx, decl, body, llfn, param_substs, id, attrs);
650 unsafe fn build_wrap_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
653 tys: &ForeignTypes<'tcx>,
655 let _icx = push_ctxt(
656 "foreign::trans_rust_fn_with_foreign_abi::build_wrap_fn");
658 debug!("build_wrap_fn(llrustfn={}, llwrapfn={}, t={:?})",
659 ccx.tn().val_to_string(llrustfn),
660 ccx.tn().val_to_string(llwrapfn),
663 // Avoid all the Rust generation stuff and just generate raw
666 // We want to generate code like this:
670 // foo0(&r, NULL, i);
674 if llvm::LLVMCountBasicBlocks(llwrapfn) != 0 {
675 ccx.sess().bug("wrapping a function inside non-empty wrapper, most likely cause is \
676 multiple functions being wrapped");
679 let ptr = "the block\0".as_ptr();
680 let the_block = llvm::LLVMAppendBasicBlockInContext(ccx.llcx(), llwrapfn,
683 let builder = ccx.builder();
684 builder.position_at_end(the_block);
686 // Array for the arguments we will pass to the rust function.
687 let mut llrust_args = Vec::new();
688 let mut next_foreign_arg_counter: c_uint = 0;
689 let mut next_foreign_arg = |pad: bool| -> c_uint {
690 next_foreign_arg_counter += if pad {
695 next_foreign_arg_counter - 1
698 // If there is an out pointer on the foreign function
699 let foreign_outptr = {
700 if tys.fn_ty.ret_ty.is_indirect() {
701 Some(get_param(llwrapfn, next_foreign_arg(false)))
707 let rustfn_ty = Type::from_ref(llvm::LLVMTypeOf(llrustfn)).element_type();
708 let mut rust_param_tys = rustfn_ty.func_params().into_iter();
709 // Push Rust return pointer, using null if it will be unused.
710 let rust_uses_outptr = match tys.fn_sig.output {
711 ty::FnConverging(ret_ty) => type_of::return_uses_outptr(ccx, ret_ty),
712 ty::FnDiverging => false
714 let return_alloca: Option<ValueRef>;
715 let llrust_ret_ty = if rust_uses_outptr {
716 rust_param_tys.next().expect("Missing return type!").element_type()
718 rustfn_ty.return_type()
720 if rust_uses_outptr {
721 // Rust expects to use an outpointer. If the foreign fn
722 // also uses an outpointer, we can reuse it, but the types
723 // may vary, so cast first to the Rust type. If the
724 // foreign fn does NOT use an outpointer, we will have to
725 // alloca some scratch space on the stack.
726 match foreign_outptr {
727 Some(llforeign_outptr) => {
728 debug!("out pointer, foreign={}",
729 ccx.tn().val_to_string(llforeign_outptr));
731 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
732 debug!("out pointer, foreign={} (casted)",
733 ccx.tn().val_to_string(llrust_retptr));
734 llrust_args.push(llrust_retptr);
735 return_alloca = None;
739 let slot = builder.alloca(llrust_ret_ty, "return_alloca");
740 debug!("out pointer, \
744 ccx.tn().val_to_string(slot),
745 ccx.tn().type_to_string(llrust_ret_ty),
747 llrust_args.push(slot);
748 return_alloca = Some(slot);
752 // Rust does not expect an outpointer. If the foreign fn
753 // does use an outpointer, then we will do a store of the
754 // value that the Rust fn returns.
755 return_alloca = None;
758 // Build up the arguments to the call to the rust function.
759 // Careful to adapt for cases where the native convention uses
760 // a pointer and Rust does not or vice versa.
761 for i in 0..tys.fn_sig.inputs.len() {
762 let rust_ty = tys.fn_sig.inputs[i];
763 let rust_indirect = type_of::arg_is_indirect(ccx, rust_ty);
764 let llty = rust_param_tys.next().expect("Not enough parameter types!");
765 let llrust_ty = if rust_indirect {
770 let llforeign_arg_ty = tys.fn_ty.arg_tys[i];
771 let foreign_indirect = llforeign_arg_ty.is_indirect();
773 if llforeign_arg_ty.is_ignore() {
774 debug!("skipping ignored arg #{}", i);
775 llrust_args.push(C_undef(llrust_ty));
780 let foreign_index = next_foreign_arg(llforeign_arg_ty.pad.is_some());
781 let mut llforeign_arg = get_param(llwrapfn, foreign_index);
783 debug!("llforeign_arg {}{}: {}", "#",
784 i, ccx.tn().val_to_string(llforeign_arg));
785 debug!("rust_indirect = {}, foreign_indirect = {}",
786 rust_indirect, foreign_indirect);
788 // Ensure that the foreign argument is indirect (by
789 // pointer). It makes adapting types easier, since we can
790 // always just bitcast pointers.
791 if !foreign_indirect {
792 llforeign_arg = if rust_ty.is_bool() {
793 let lltemp = builder.alloca(Type::bool(ccx), "");
794 builder.store(builder.zext(llforeign_arg, Type::bool(ccx)), lltemp);
797 let lltemp = builder.alloca(val_ty(llforeign_arg), "");
798 builder.store(llforeign_arg, lltemp);
803 // If the types in the ABI and the Rust types don't match,
804 // bitcast the llforeign_arg pointer so it matches the types
806 if llforeign_arg_ty.cast.is_some() && !type_is_fat_ptr(ccx.tcx(), rust_ty){
807 assert!(!foreign_indirect);
808 llforeign_arg = builder.bitcast(llforeign_arg, llrust_ty.ptr_to());
811 let llrust_arg = if rust_indirect || type_is_fat_ptr(ccx.tcx(), rust_ty) {
814 if rust_ty.is_bool() {
815 let tmp = builder.load_range_assert(llforeign_arg, 0, 2, llvm::False);
816 builder.trunc(tmp, Type::i1(ccx))
817 } else if type_of::type_of(ccx, rust_ty).is_aggregate() {
818 // We want to pass small aggregates as immediate values, but using an aggregate
819 // LLVM type for this leads to bad optimizations, so its arg type is an
820 // appropriately sized integer and we have to convert it
821 let tmp = builder.bitcast(llforeign_arg,
822 type_of::arg_type_of(ccx, rust_ty).ptr_to());
823 let load = builder.load(tmp);
824 llvm::LLVMSetAlignment(load, type_of::align_of(ccx, rust_ty));
827 builder.load(llforeign_arg)
831 debug!("llrust_arg {}{}: {}", "#",
832 i, ccx.tn().val_to_string(llrust_arg));
833 if type_is_fat_ptr(ccx.tcx(), rust_ty) {
834 let next_llrust_ty = rust_param_tys.next().expect("Not enough parameter types!");
835 llrust_args.push(builder.load(builder.bitcast(builder.struct_gep(
836 llrust_arg, abi::FAT_PTR_ADDR), llrust_ty.ptr_to())));
837 llrust_args.push(builder.load(builder.bitcast(builder.struct_gep(
838 llrust_arg, abi::FAT_PTR_EXTRA), next_llrust_ty.ptr_to())));
840 llrust_args.push(llrust_arg);
844 // Perform the call itself
845 debug!("calling llrustfn = {}, t = {:?}",
846 ccx.tn().val_to_string(llrustfn), t);
847 let attributes = attributes::from_fn_type(ccx, t);
848 let llrust_ret_val = builder.call(llrustfn, &llrust_args,
849 None, Some(attributes));
851 // Get the return value where the foreign fn expects it.
852 let llforeign_ret_ty = match tys.fn_ty.ret_ty.cast {
854 None => tys.fn_ty.ret_ty.ty
856 match foreign_outptr {
857 None if !tys.llsig.ret_def => {
858 // Function returns `()` or `bot`, which in Rust is the LLVM
859 // type "{}" but in foreign ABIs is "Void".
863 None if rust_uses_outptr => {
864 // Rust uses an outpointer, but the foreign ABI does not. Load.
865 let llrust_outptr = return_alloca.unwrap();
866 let llforeign_outptr_casted =
867 builder.bitcast(llrust_outptr, llforeign_ret_ty.ptr_to());
868 let llforeign_retval = builder.load(llforeign_outptr_casted);
869 builder.ret(llforeign_retval);
872 None if llforeign_ret_ty != llrust_ret_ty => {
873 // Neither ABI uses an outpointer, but the types don't
874 // quite match. Must cast. Probably we should try and
875 // examine the types and use a concrete llvm cast, but
876 // right now we just use a temp memory location and
877 // bitcast the pointer, which is the same thing the
878 // old wrappers used to do.
879 let lltemp = builder.alloca(llforeign_ret_ty, "");
880 let lltemp_casted = builder.bitcast(lltemp, llrust_ret_ty.ptr_to());
881 builder.store(llrust_ret_val, lltemp_casted);
882 let llforeign_retval = builder.load(lltemp);
883 builder.ret(llforeign_retval);
887 // Neither ABI uses an outpointer, and the types
888 // match. Easy peasy.
889 builder.ret(llrust_ret_val);
892 Some(llforeign_outptr) if !rust_uses_outptr => {
893 // Foreign ABI requires an out pointer, but Rust doesn't.
894 // Store Rust return value.
895 let llforeign_outptr_casted =
896 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
897 builder.store(llrust_ret_val, llforeign_outptr_casted);
902 // Both ABIs use outpointers. Easy peasy.
909 ///////////////////////////////////////////////////////////////////////////
910 // General ABI Support
912 // This code is kind of a confused mess and needs to be reworked given
913 // the massive simplifications that have occurred.
915 pub fn link_name(i: &hir::ForeignItem) -> InternedString {
916 match attr::first_attr_value_str_by_name(&i.attrs, "link_name") {
917 Some(ln) => ln.clone(),
918 None => match weak_lang_items::link_name(&i.attrs) {
920 None => i.name.as_str(),
925 /// The ForeignSignature is the LLVM types of the arguments/return type of a function. Note that
926 /// these LLVM types are not quite the same as the LLVM types would be for a native Rust function
927 /// because foreign functions just plain ignore modes. They also don't pass aggregate values by
928 /// pointer like we do.
929 fn foreign_signature<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
930 fn_sig: &ty::FnSig<'tcx>,
931 arg_tys: &[Ty<'tcx>])
933 let llarg_tys = arg_tys.iter().map(|&arg| foreign_arg_type_of(ccx, arg)).collect();
934 let (llret_ty, ret_def) = match fn_sig.output {
935 ty::FnConverging(ret_ty) =>
936 (type_of::foreign_arg_type_of(ccx, ret_ty), !return_type_is_void(ccx, ret_ty)),
938 (Type::nil(ccx), false)
941 llarg_tys: llarg_tys,
947 fn foreign_types_for_fn_ty<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
948 ty: Ty<'tcx>) -> ForeignTypes<'tcx> {
949 let fn_sig = match ty.sty {
950 ty::TyBareFn(_, ref fn_ty) => &fn_ty.sig,
951 _ => ccx.sess().bug("foreign_types_for_fn_ty called on non-function type")
953 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
954 let fn_sig = infer::normalize_associated_type(ccx.tcx(), &fn_sig);
955 let llsig = foreign_signature(ccx, &fn_sig, &fn_sig.inputs);
956 let fn_ty = cabi::compute_abi_info(ccx,
960 debug!("foreign_types_for_fn_ty(\
966 ccx.tn().types_to_str(&llsig.llarg_tys),
967 ccx.tn().type_to_string(llsig.llret_ty),
968 ccx.tn().types_to_str(&fn_ty.arg_tys.iter().map(|t| t.ty).collect::<Vec<_>>()),
969 ccx.tn().type_to_string(fn_ty.ret_ty.ty),
979 fn lltype_for_fn_from_foreign_types(ccx: &CrateContext, tys: &ForeignTypes) -> Type {
980 let mut llargument_tys = Vec::new();
982 let ret_ty = tys.fn_ty.ret_ty;
983 let llreturn_ty = if ret_ty.is_indirect() {
984 llargument_tys.push(ret_ty.ty.ptr_to());
993 for &arg_ty in &tys.fn_ty.arg_tys {
994 if arg_ty.is_ignore() {
999 Some(ty) => llargument_tys.push(ty),
1003 let llarg_ty = if arg_ty.is_indirect() {
1012 llargument_tys.push(llarg_ty);
1015 if tys.fn_sig.variadic {
1016 Type::variadic_func(&llargument_tys, &llreturn_ty)
1018 Type::func(&llargument_tys[..], &llreturn_ty)
1022 pub fn lltype_for_foreign_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
1023 ty: Ty<'tcx>) -> Type {
1024 lltype_for_fn_from_foreign_types(ccx, &foreign_types_for_fn_ty(ccx, ty))
1027 fn add_argument_attributes(tys: &ForeignTypes,
1029 let mut i = if tys.fn_ty.ret_ty.is_indirect() {
1035 match tys.fn_ty.ret_ty.attr {
1036 Some(attr) => unsafe {
1037 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);
1044 for &arg_ty in &tys.fn_ty.arg_tys {
1045 if arg_ty.is_ignore() {
1049 if arg_ty.pad.is_some() { i += 1; }
1052 Some(attr) => unsafe {
1053 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);