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::*;
30 use middle::ty::{self, Ty};
31 use middle::subst::Substs;
32 use rustc::front::map as hir_map;
36 use syntax::abi::{Cdecl, Aapcs, C, Win64, Abi};
37 use syntax::abi::{PlatformIntrinsic, RustIntrinsic, Rust, RustCall, Stdcall, Fastcall, System};
38 use syntax::codemap::Span;
39 use syntax::parse::token::{InternedString, special_idents};
42 use rustc_front::print::pprust;
43 use rustc_front::attr;
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 match ccx.sess().target.target.adjust_abi(abi) {
83 // Intrinsics are emitted at the call site
84 ccx.sess().bug("asked to register intrinsic fn");
86 PlatformIntrinsic => {
87 // Intrinsics are emitted at the call site
88 ccx.sess().bug("asked to register platform intrinsic fn");
92 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
93 ccx.sess().unimpl("foreign functions with Rust ABI");
97 // FIXME(#3678) Implement linking to foreign fns with Rust ABI
98 ccx.sess().unimpl("foreign functions with RustCall ABI");
101 // It's the ABI's job to select this, not us.
102 System => ccx.sess().bug("system abi should be selected elsewhere"),
104 Stdcall => llvm::X86StdcallCallConv,
105 Fastcall => llvm::X86FastcallCallConv,
106 C => llvm::CCallConv,
107 Win64 => llvm::X86_64_Win64,
109 // These API constants ought to be more specific...
110 Cdecl => llvm::CCallConv,
111 Aapcs => llvm::CCallConv,
115 pub fn register_static(ccx: &CrateContext,
116 foreign_item: &hir::ForeignItem) -> ValueRef {
117 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
118 let llty = type_of::type_of(ccx, ty);
120 let ident = link_name(foreign_item);
121 match attr::first_attr_value_str_by_name(&foreign_item.attrs,
123 // If this is a static with a linkage specified, then we need to handle
124 // it a little specially. The typesystem prevents things like &T and
125 // extern "C" fn() from being non-null, so we can't just declare a
126 // static and call it a day. Some linkages (like weak) will make it such
127 // that the static actually has a null value.
129 let linkage = match llvm_linkage_by_name(&name) {
130 Some(linkage) => linkage,
132 ccx.sess().span_fatal(foreign_item.span,
133 "invalid linkage specified");
136 let llty2 = match ty.sty {
137 ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty),
139 ccx.sess().span_fatal(foreign_item.span,
140 "must have type `*T` or `*mut T`");
144 // Declare a symbol `foo` with the desired linkage.
145 let g1 = declare::declare_global(ccx, &ident[..], llty2);
146 llvm::SetLinkage(g1, linkage);
148 // Declare an internal global `extern_with_linkage_foo` which
149 // is initialized with the address of `foo`. If `foo` is
150 // discarded during linking (for example, if `foo` has weak
151 // linkage and there are no definitions), then
152 // `extern_with_linkage_foo` will instead be initialized to
154 let mut real_name = "_rust_extern_with_linkage_".to_string();
155 real_name.push_str(&ident);
156 let g2 = declare::define_global(ccx, &real_name[..], llty).unwrap_or_else(||{
157 ccx.sess().span_fatal(foreign_item.span,
158 &format!("symbol `{}` is already defined", ident))
160 llvm::SetLinkage(g2, llvm::InternalLinkage);
161 llvm::LLVMSetInitializer(g2, g1);
165 None => // Generate an external declaration.
166 declare::declare_global(ccx, &ident[..], llty),
170 // only use this for foreign function ABIs and glue, use `get_extern_rust_fn` for Rust functions
171 pub fn get_extern_fn(ccx: &CrateContext,
172 externs: &mut ExternMap,
178 match externs.get(name) {
179 Some(n) => return *n,
182 let f = declare::declare_fn(ccx, name, cc, ty, ty::FnConverging(output));
183 externs.insert(name.to_string(), f);
187 /// Registers a foreign function found in a library. Just adds a LLVM global.
188 pub fn register_foreign_item_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
189 abi: Abi, fty: Ty<'tcx>,
191 attrs: &[hir::Attribute])-> ValueRef {
192 debug!("register_foreign_item_fn(abi={:?}, \
199 let cc = llvm_calling_convention(ccx, abi);
201 // Register the function as a C extern fn
202 let tys = foreign_types_for_fn_ty(ccx, fty);
204 // Make sure the calling convention is right for variadic functions
205 // (should've been caught if not in typeck)
206 if tys.fn_sig.variadic {
207 assert!(cc == llvm::CCallConv);
210 // Create the LLVM value for the C extern fn
211 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
213 let llfn = get_extern_fn(ccx, &mut *ccx.externs().borrow_mut(), name, cc, llfn_ty, fty);
214 add_argument_attributes(&tys, llfn);
215 attributes::from_fn_attrs(ccx, attrs, llfn);
219 /// Prepares a call to a native function. This requires adapting
220 /// from the Rust argument passing rules to the native rules.
224 /// - `callee_ty`: Rust type for the function we are calling
225 /// - `llfn`: the function pointer we are calling
226 /// - `llretptr`: where to store the return value of the function
227 /// - `llargs_rust`: a list of the argument values, prepared
228 /// as they would be if calling a Rust function
229 /// - `passed_arg_tys`: Rust type for the arguments. Normally we
230 /// can derive these from callee_ty but in the case of variadic
231 /// functions passed_arg_tys will include the Rust type of all
232 /// the arguments including the ones not specified in the fn's signature.
233 pub fn trans_native_call<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
237 llargs_rust: &[ValueRef],
238 passed_arg_tys: Vec<Ty<'tcx>>,
239 call_debug_loc: DebugLoc)
244 debug!("trans_native_call(callee_ty={:?}, \
248 ccx.tn().val_to_string(llfn),
249 ccx.tn().val_to_string(llretptr));
251 let (fn_abi, fn_sig) = match callee_ty.sty {
252 ty::TyBareFn(_, ref fn_ty) => (fn_ty.abi, &fn_ty.sig),
253 _ => ccx.sess().bug("trans_native_call called on non-function type")
255 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
256 let llsig = foreign_signature(ccx, &fn_sig, &passed_arg_tys[..]);
257 let fn_type = cabi::compute_abi_info(ccx,
262 let arg_tys: &[cabi::ArgType] = &fn_type.arg_tys;
264 let mut llargs_foreign = Vec::new();
266 // If the foreign ABI expects return value by pointer, supply the
267 // pointer that Rust gave us. Sometimes we have to bitcast
268 // because foreign fns return slightly different (but equivalent)
269 // views on the same type (e.g., i64 in place of {i32,i32}).
270 if fn_type.ret_ty.is_indirect() {
271 match fn_type.ret_ty.cast {
274 BitCast(bcx, llretptr, ty.ptr_to());
275 llargs_foreign.push(llcastedretptr);
278 llargs_foreign.push(llretptr);
284 for (i, arg_ty) in arg_tys.iter().enumerate() {
285 let mut llarg_rust = llargs_rust[i + offset];
287 if arg_ty.is_ignore() {
291 // Does Rust pass this argument by pointer?
292 let rust_indirect = type_of::arg_is_indirect(ccx, passed_arg_tys[i]);
294 debug!("argument {}, llarg_rust={}, rust_indirect={}, arg_ty={}",
296 ccx.tn().val_to_string(llarg_rust),
298 ccx.tn().type_to_string(arg_ty.ty));
300 // Ensure that we always have the Rust value indirectly,
301 // because it makes bitcasting easier.
303 let scratch = base::alloc_ty(bcx, passed_arg_tys[i], "__arg");
304 if type_is_fat_ptr(ccx.tcx(), passed_arg_tys[i]) {
305 Store(bcx, llargs_rust[i + offset], expr::get_dataptr(bcx, scratch));
306 Store(bcx, llargs_rust[i + offset + 1], expr::get_meta(bcx, scratch));
309 base::store_ty(bcx, llarg_rust, scratch, passed_arg_tys[i]);
311 llarg_rust = scratch;
314 debug!("llarg_rust={} (after indirection)",
315 ccx.tn().val_to_string(llarg_rust));
317 // Check whether we need to do any casting
319 Some(ty) => llarg_rust = BitCast(bcx, llarg_rust, ty.ptr_to()),
323 debug!("llarg_rust={} (after casting)",
324 ccx.tn().val_to_string(llarg_rust));
326 // Finally, load the value if needed for the foreign ABI
327 let foreign_indirect = arg_ty.is_indirect();
328 let llarg_foreign = if foreign_indirect {
331 if passed_arg_tys[i].is_bool() {
332 let val = LoadRangeAssert(bcx, llarg_rust, 0, 2, llvm::False);
333 Trunc(bcx, val, Type::i1(bcx.ccx()))
335 Load(bcx, llarg_rust)
339 debug!("argument {}, llarg_foreign={}",
340 i, ccx.tn().val_to_string(llarg_foreign));
342 // fill padding with undef value
344 Some(ty) => llargs_foreign.push(C_undef(ty)),
347 llargs_foreign.push(llarg_foreign);
350 let cc = llvm_calling_convention(ccx, fn_abi);
352 // A function pointer is called without the declaration available, so we have to apply
353 // any attributes with ABI implications directly to the call instruction.
354 let mut attrs = llvm::AttrBuilder::new();
356 // Add attributes that are always applicable, independent of the concrete foreign ABI
357 if fn_type.ret_ty.is_indirect() {
358 let llret_sz = machine::llsize_of_real(ccx, fn_type.ret_ty.ty);
360 // The outptr can be noalias and nocapture because it's entirely
361 // invisible to the program. We also know it's nonnull as well
362 // as how many bytes we can dereference
363 attrs.arg(1, llvm::Attribute::NoAlias)
364 .arg(1, llvm::Attribute::NoCapture)
365 .arg(1, llvm::DereferenceableAttribute(llret_sz));
368 // Add attributes that depend on the concrete foreign ABI
369 let mut arg_idx = if fn_type.ret_ty.is_indirect() { 1 } else { 0 };
370 match fn_type.ret_ty.attr {
371 Some(attr) => { attrs.arg(arg_idx, attr); },
376 for arg_ty in &fn_type.arg_tys {
377 if arg_ty.is_ignore() {
381 if arg_ty.pad.is_some() { arg_idx += 1; }
383 if let Some(attr) = arg_ty.attr {
384 attrs.arg(arg_idx, attr);
390 let llforeign_retval = CallWithConv(bcx,
397 // If the function we just called does not use an outpointer,
398 // store the result into the rust outpointer. Cast the outpointer
399 // type to match because some ABIs will use a different type than
400 // the Rust type. e.g., a {u32,u32} struct could be returned as
402 if llsig.ret_def && !fn_type.ret_ty.is_indirect() {
403 let llrust_ret_ty = llsig.llret_ty;
404 let llforeign_ret_ty = match fn_type.ret_ty.cast {
406 None => fn_type.ret_ty.ty
409 debug!("llretptr={}", ccx.tn().val_to_string(llretptr));
410 debug!("llforeign_retval={}", ccx.tn().val_to_string(llforeign_retval));
411 debug!("llrust_ret_ty={}", ccx.tn().type_to_string(llrust_ret_ty));
412 debug!("llforeign_ret_ty={}", ccx.tn().type_to_string(llforeign_ret_ty));
414 if llrust_ret_ty == llforeign_ret_ty {
415 match fn_sig.output {
416 ty::FnConverging(result_ty) => {
417 base::store_ty(bcx, llforeign_retval, llretptr, result_ty)
419 ty::FnDiverging => {}
422 // The actual return type is a struct, but the ABI
423 // adaptation code has cast it into some scalar type. The
424 // code that follows is the only reliable way I have
425 // found to do a transform like i64 -> {i32,i32}.
426 // Basically we dump the data onto the stack then memcpy it.
428 // Other approaches I tried:
429 // - Casting rust ret pointer to the foreign type and using Store
430 // is (a) unsafe if size of foreign type > size of rust type and
431 // (b) runs afoul of strict aliasing rules, yielding invalid
432 // assembly under -O (specifically, the store gets removed).
433 // - Truncating foreign type to correct integral type and then
434 // bitcasting to the struct type yields invalid cast errors.
435 let llscratch = base::alloca(bcx, llforeign_ret_ty, "__cast");
436 base::call_lifetime_start(bcx, llscratch);
437 Store(bcx, llforeign_retval, llscratch);
438 let llscratch_i8 = BitCast(bcx, llscratch, Type::i8(ccx).ptr_to());
439 let llretptr_i8 = BitCast(bcx, llretptr, Type::i8(ccx).ptr_to());
440 let llrust_size = machine::llsize_of_store(ccx, llrust_ret_ty);
441 let llforeign_align = machine::llalign_of_min(ccx, llforeign_ret_ty);
442 let llrust_align = machine::llalign_of_min(ccx, llrust_ret_ty);
443 let llalign = cmp::min(llforeign_align, llrust_align);
444 debug!("llrust_size={}", llrust_size);
445 base::call_memcpy(bcx, llretptr_i8, llscratch_i8,
446 C_uint(ccx, llrust_size), llalign as u32);
447 base::call_lifetime_end(bcx, llscratch);
454 // feature gate SIMD types in FFI, since I (huonw) am not sure the
455 // ABIs are handled at all correctly.
456 fn gate_simd_ffi(tcx: &ty::ctxt, decl: &hir::FnDecl, ty: &ty::BareFnTy) {
457 if !tcx.sess.features.borrow().simd_ffi {
458 let check = |ast_ty: &hir::Ty, ty: ty::Ty| {
460 tcx.sess.span_err(ast_ty.span,
461 &format!("use of SIMD type `{}` in FFI is highly experimental and \
462 may result in invalid code",
463 pprust::ty_to_string(ast_ty)));
464 tcx.sess.fileline_help(ast_ty.span,
465 "add #![feature(simd_ffi)] to the crate attributes to enable");
469 for (input, ty) in decl.inputs.iter().zip(&sig.inputs) {
470 check(&*input.ty, *ty)
472 if let hir::Return(ref ty) = decl.output {
473 check(&**ty, sig.output.unwrap())
478 pub fn trans_foreign_mod(ccx: &CrateContext, foreign_mod: &hir::ForeignMod) {
479 let _icx = push_ctxt("foreign::trans_foreign_mod");
480 for foreign_item in &foreign_mod.items {
481 let lname = link_name(&**foreign_item);
483 if let hir::ForeignItemFn(ref decl, _) = foreign_item.node {
484 match foreign_mod.abi {
485 Rust | RustIntrinsic | PlatformIntrinsic => {}
487 let ty = ccx.tcx().node_id_to_type(foreign_item.id);
489 ty::TyBareFn(_, bft) => gate_simd_ffi(ccx.tcx(), &**decl, bft),
490 _ => ccx.tcx().sess.span_bug(foreign_item.span,
491 "foreign fn's sty isn't a bare_fn_ty?")
494 register_foreign_item_fn(ccx, abi, ty, &lname, &foreign_item.attrs);
495 // Unlike for other items, we shouldn't call
496 // `base::update_linkage` here. Foreign items have
497 // special linkage requirements, which are handled
498 // inside `foreign::register_*`.
503 ccx.item_symbols().borrow_mut().insert(foreign_item.id,
508 ///////////////////////////////////////////////////////////////////////////
509 // Rust functions with foreign ABIs
511 // These are normal Rust functions defined with foreign ABIs. For
512 // now, and perhaps forever, we translate these using a "layer of
513 // indirection". That is, given a Rust declaration like:
515 // extern "C" fn foo(i: u32) -> u32 { ... }
517 // we will generate a function like:
521 // foo0(&r, NULL, i);
526 // void foo0(uint32_t *r, void *env, uint32_t i) { ... }
528 // Here the (internal) `foo0` function follows the Rust ABI as normal,
529 // where the `foo` function follows the C ABI. We rely on LLVM to
530 // inline the one into the other. Of course we could just generate the
531 // correct code in the first place, but this is much simpler.
533 pub fn decl_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
537 let tys = foreign_types_for_fn_ty(ccx, t);
538 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
539 let cconv = match t.sty {
540 ty::TyBareFn(_, ref fn_ty) => {
541 llvm_calling_convention(ccx, fn_ty.abi)
543 _ => panic!("expected bare fn in decl_rust_fn_with_foreign_abi")
545 let llfn = declare::declare_fn(ccx, name, cconv, llfn_ty,
546 ty::FnConverging(ccx.tcx().mk_nil()));
547 add_argument_attributes(&tys, llfn);
548 debug!("decl_rust_fn_with_foreign_abi(llfn_ty={}, llfn={})",
549 ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
553 pub fn register_rust_fn_with_foreign_abi(ccx: &CrateContext,
556 node_id: ast::NodeId)
558 let _icx = push_ctxt("foreign::register_foreign_fn");
560 let tys = foreign_types_for_id(ccx, node_id);
561 let llfn_ty = lltype_for_fn_from_foreign_types(ccx, &tys);
562 let t = ccx.tcx().node_id_to_type(node_id);
563 let cconv = match t.sty {
564 ty::TyBareFn(_, ref fn_ty) => {
565 llvm_calling_convention(ccx, fn_ty.abi)
567 _ => panic!("expected bare fn in register_rust_fn_with_foreign_abi")
569 let llfn = base::register_fn_llvmty(ccx, sp, sym, node_id, cconv, llfn_ty);
570 add_argument_attributes(&tys, llfn);
571 debug!("register_rust_fn_with_foreign_abi(node_id={}, llfn_ty={}, llfn={})",
572 node_id, ccx.tn().type_to_string(llfn_ty), ccx.tn().val_to_string(llfn));
576 pub fn trans_rust_fn_with_foreign_abi<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
579 attrs: &[hir::Attribute],
581 param_substs: &'tcx Substs<'tcx>,
583 hash: Option<&str>) {
584 let _icx = push_ctxt("foreign::build_foreign_fn");
586 let fnty = ccx.tcx().node_id_to_type(id);
587 let mty = monomorphize::apply_param_substs(ccx.tcx(), param_substs, &fnty);
588 let tys = foreign_types_for_fn_ty(ccx, mty);
590 unsafe { // unsafe because we call LLVM operations
591 // Build up the Rust function (`foo0` above).
592 let llrustfn = build_rust_fn(ccx, decl, body, param_substs, attrs, id, hash);
594 // Build up the foreign wrapper (`foo` above).
595 return build_wrap_fn(ccx, llrustfn, llwrapfn, &tys, mty);
598 fn build_rust_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
601 param_substs: &'tcx Substs<'tcx>,
602 attrs: &[hir::Attribute],
607 let _icx = push_ctxt("foreign::foreign::build_rust_fn");
609 let t = tcx.node_id_to_type(id);
610 let t = monomorphize::apply_param_substs(tcx, param_substs, &t);
612 let ps = ccx.tcx().map.with_path(id, |path| {
613 let abi = Some(hir_map::PathName(special_idents::clownshoe_abi.name));
614 link::mangle(path.chain(abi), hash)
617 // Compute the type that the function would have if it were just a
618 // normal Rust function. This will be the type of the wrappee fn.
620 ty::TyBareFn(_, ref f) => {
621 assert!(f.abi != Rust && f.abi != RustIntrinsic && f.abi != PlatformIntrinsic);
624 ccx.sess().bug(&format!("build_rust_fn: extern fn {} has ty {:?}, \
625 expected a bare fn ty",
626 ccx.tcx().map.path_to_string(id),
631 debug!("build_rust_fn: path={} id={} t={:?}",
632 ccx.tcx().map.path_to_string(id),
635 let llfn = declare::define_internal_rust_fn(ccx, &ps, t);
636 attributes::from_fn_attrs(ccx, attrs, llfn);
637 base::trans_fn(ccx, decl, body, llfn, param_substs, id, &[]);
641 unsafe fn build_wrap_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
644 tys: &ForeignTypes<'tcx>,
646 let _icx = push_ctxt(
647 "foreign::trans_rust_fn_with_foreign_abi::build_wrap_fn");
649 debug!("build_wrap_fn(llrustfn={}, llwrapfn={}, t={:?})",
650 ccx.tn().val_to_string(llrustfn),
651 ccx.tn().val_to_string(llwrapfn),
654 // Avoid all the Rust generation stuff and just generate raw
657 // We want to generate code like this:
661 // foo0(&r, NULL, i);
665 if llvm::LLVMCountBasicBlocks(llwrapfn) != 0 {
666 ccx.sess().bug("wrapping a function inside non-empty wrapper, most likely cause is \
667 multiple functions being wrapped");
670 let ptr = "the block\0".as_ptr();
671 let the_block = llvm::LLVMAppendBasicBlockInContext(ccx.llcx(), llwrapfn,
674 let builder = ccx.builder();
675 builder.position_at_end(the_block);
677 // Array for the arguments we will pass to the rust function.
678 let mut llrust_args = Vec::new();
679 let mut next_foreign_arg_counter: c_uint = 0;
680 let mut next_foreign_arg = |pad: bool| -> c_uint {
681 next_foreign_arg_counter += if pad {
686 next_foreign_arg_counter - 1
689 // If there is an out pointer on the foreign function
690 let foreign_outptr = {
691 if tys.fn_ty.ret_ty.is_indirect() {
692 Some(get_param(llwrapfn, next_foreign_arg(false)))
698 let rustfn_ty = Type::from_ref(llvm::LLVMTypeOf(llrustfn)).element_type();
699 let mut rust_param_tys = rustfn_ty.func_params().into_iter();
700 // Push Rust return pointer, using null if it will be unused.
701 let rust_uses_outptr = match tys.fn_sig.output {
702 ty::FnConverging(ret_ty) => type_of::return_uses_outptr(ccx, ret_ty),
703 ty::FnDiverging => false
705 let return_alloca: Option<ValueRef>;
706 let llrust_ret_ty = if rust_uses_outptr {
707 rust_param_tys.next().expect("Missing return type!").element_type()
709 rustfn_ty.return_type()
711 if rust_uses_outptr {
712 // Rust expects to use an outpointer. If the foreign fn
713 // also uses an outpointer, we can reuse it, but the types
714 // may vary, so cast first to the Rust type. If the
715 // foreign fn does NOT use an outpointer, we will have to
716 // alloca some scratch space on the stack.
717 match foreign_outptr {
718 Some(llforeign_outptr) => {
719 debug!("out pointer, foreign={}",
720 ccx.tn().val_to_string(llforeign_outptr));
722 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
723 debug!("out pointer, foreign={} (casted)",
724 ccx.tn().val_to_string(llrust_retptr));
725 llrust_args.push(llrust_retptr);
726 return_alloca = None;
730 let slot = builder.alloca(llrust_ret_ty, "return_alloca");
731 debug!("out pointer, \
735 ccx.tn().val_to_string(slot),
736 ccx.tn().type_to_string(llrust_ret_ty),
738 llrust_args.push(slot);
739 return_alloca = Some(slot);
743 // Rust does not expect an outpointer. If the foreign fn
744 // does use an outpointer, then we will do a store of the
745 // value that the Rust fn returns.
746 return_alloca = None;
749 // Build up the arguments to the call to the rust function.
750 // Careful to adapt for cases where the native convention uses
751 // a pointer and Rust does not or vice versa.
752 for i in 0..tys.fn_sig.inputs.len() {
753 let rust_ty = tys.fn_sig.inputs[i];
754 let rust_indirect = type_of::arg_is_indirect(ccx, rust_ty);
755 let llty = rust_param_tys.next().expect("Not enough parameter types!");
756 let llrust_ty = if rust_indirect {
761 let llforeign_arg_ty = tys.fn_ty.arg_tys[i];
762 let foreign_indirect = llforeign_arg_ty.is_indirect();
764 if llforeign_arg_ty.is_ignore() {
765 debug!("skipping ignored arg #{}", i);
766 llrust_args.push(C_undef(llrust_ty));
771 let foreign_index = next_foreign_arg(llforeign_arg_ty.pad.is_some());
772 let mut llforeign_arg = get_param(llwrapfn, foreign_index);
774 debug!("llforeign_arg {}{}: {}", "#",
775 i, ccx.tn().val_to_string(llforeign_arg));
776 debug!("rust_indirect = {}, foreign_indirect = {}",
777 rust_indirect, foreign_indirect);
779 // Ensure that the foreign argument is indirect (by
780 // pointer). It makes adapting types easier, since we can
781 // always just bitcast pointers.
782 if !foreign_indirect {
783 llforeign_arg = if rust_ty.is_bool() {
784 let lltemp = builder.alloca(Type::bool(ccx), "");
785 builder.store(builder.zext(llforeign_arg, Type::bool(ccx)), lltemp);
788 let lltemp = builder.alloca(val_ty(llforeign_arg), "");
789 builder.store(llforeign_arg, lltemp);
794 // If the types in the ABI and the Rust types don't match,
795 // bitcast the llforeign_arg pointer so it matches the types
797 if llforeign_arg_ty.cast.is_some() && !type_is_fat_ptr(ccx.tcx(), rust_ty){
798 assert!(!foreign_indirect);
799 llforeign_arg = builder.bitcast(llforeign_arg, llrust_ty.ptr_to());
802 let llrust_arg = if rust_indirect || type_is_fat_ptr(ccx.tcx(), rust_ty) {
805 if rust_ty.is_bool() {
806 let tmp = builder.load_range_assert(llforeign_arg, 0, 2, llvm::False);
807 builder.trunc(tmp, Type::i1(ccx))
808 } else if type_of::type_of(ccx, rust_ty).is_aggregate() {
809 // We want to pass small aggregates as immediate values, but using an aggregate
810 // LLVM type for this leads to bad optimizations, so its arg type is an
811 // appropriately sized integer and we have to convert it
812 let tmp = builder.bitcast(llforeign_arg,
813 type_of::arg_type_of(ccx, rust_ty).ptr_to());
814 let load = builder.load(tmp);
815 llvm::LLVMSetAlignment(load, type_of::align_of(ccx, rust_ty));
818 builder.load(llforeign_arg)
822 debug!("llrust_arg {}{}: {}", "#",
823 i, ccx.tn().val_to_string(llrust_arg));
824 if type_is_fat_ptr(ccx.tcx(), rust_ty) {
825 let next_llrust_ty = rust_param_tys.next().expect("Not enough parameter types!");
826 llrust_args.push(builder.load(builder.bitcast(builder.struct_gep(
827 llrust_arg, abi::FAT_PTR_ADDR), llrust_ty.ptr_to())));
828 llrust_args.push(builder.load(builder.bitcast(builder.struct_gep(
829 llrust_arg, abi::FAT_PTR_EXTRA), next_llrust_ty.ptr_to())));
831 llrust_args.push(llrust_arg);
835 // Perform the call itself
836 debug!("calling llrustfn = {}, t = {:?}",
837 ccx.tn().val_to_string(llrustfn), t);
838 let attributes = attributes::from_fn_type(ccx, t);
839 let llrust_ret_val = builder.call(llrustfn, &llrust_args, Some(attributes));
841 // Get the return value where the foreign fn expects it.
842 let llforeign_ret_ty = match tys.fn_ty.ret_ty.cast {
844 None => tys.fn_ty.ret_ty.ty
846 match foreign_outptr {
847 None if !tys.llsig.ret_def => {
848 // Function returns `()` or `bot`, which in Rust is the LLVM
849 // type "{}" but in foreign ABIs is "Void".
853 None if rust_uses_outptr => {
854 // Rust uses an outpointer, but the foreign ABI does not. Load.
855 let llrust_outptr = return_alloca.unwrap();
856 let llforeign_outptr_casted =
857 builder.bitcast(llrust_outptr, llforeign_ret_ty.ptr_to());
858 let llforeign_retval = builder.load(llforeign_outptr_casted);
859 builder.ret(llforeign_retval);
862 None if llforeign_ret_ty != llrust_ret_ty => {
863 // Neither ABI uses an outpointer, but the types don't
864 // quite match. Must cast. Probably we should try and
865 // examine the types and use a concrete llvm cast, but
866 // right now we just use a temp memory location and
867 // bitcast the pointer, which is the same thing the
868 // old wrappers used to do.
869 let lltemp = builder.alloca(llforeign_ret_ty, "");
870 let lltemp_casted = builder.bitcast(lltemp, llrust_ret_ty.ptr_to());
871 builder.store(llrust_ret_val, lltemp_casted);
872 let llforeign_retval = builder.load(lltemp);
873 builder.ret(llforeign_retval);
877 // Neither ABI uses an outpointer, and the types
878 // match. Easy peasy.
879 builder.ret(llrust_ret_val);
882 Some(llforeign_outptr) if !rust_uses_outptr => {
883 // Foreign ABI requires an out pointer, but Rust doesn't.
884 // Store Rust return value.
885 let llforeign_outptr_casted =
886 builder.bitcast(llforeign_outptr, llrust_ret_ty.ptr_to());
887 builder.store(llrust_ret_val, llforeign_outptr_casted);
892 // Both ABIs use outpointers. Easy peasy.
899 ///////////////////////////////////////////////////////////////////////////
900 // General ABI Support
902 // This code is kind of a confused mess and needs to be reworked given
903 // the massive simplifications that have occurred.
905 pub fn link_name(i: &hir::ForeignItem) -> InternedString {
906 match attr::first_attr_value_str_by_name(&i.attrs, "link_name") {
907 Some(ln) => ln.clone(),
908 None => match weak_lang_items::link_name(&i.attrs) {
910 None => i.ident.name.as_str(),
915 /// The ForeignSignature is the LLVM types of the arguments/return type of a function. Note that
916 /// these LLVM types are not quite the same as the LLVM types would be for a native Rust function
917 /// because foreign functions just plain ignore modes. They also don't pass aggregate values by
918 /// pointer like we do.
919 fn foreign_signature<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
920 fn_sig: &ty::FnSig<'tcx>,
921 arg_tys: &[Ty<'tcx>])
923 let llarg_tys = arg_tys.iter().map(|&arg| foreign_arg_type_of(ccx, arg)).collect();
924 let (llret_ty, ret_def) = match fn_sig.output {
925 ty::FnConverging(ret_ty) =>
926 (type_of::foreign_arg_type_of(ccx, ret_ty), !return_type_is_void(ccx, ret_ty)),
928 (Type::nil(ccx), false)
931 llarg_tys: llarg_tys,
937 fn foreign_types_for_id<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
938 id: ast::NodeId) -> ForeignTypes<'tcx> {
939 foreign_types_for_fn_ty(ccx, ccx.tcx().node_id_to_type(id))
942 fn foreign_types_for_fn_ty<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
943 ty: Ty<'tcx>) -> ForeignTypes<'tcx> {
944 let fn_sig = match ty.sty {
945 ty::TyBareFn(_, ref fn_ty) => &fn_ty.sig,
946 _ => ccx.sess().bug("foreign_types_for_fn_ty called on non-function type")
948 let fn_sig = ccx.tcx().erase_late_bound_regions(fn_sig);
949 let llsig = foreign_signature(ccx, &fn_sig, &fn_sig.inputs);
950 let fn_ty = cabi::compute_abi_info(ccx,
954 debug!("foreign_types_for_fn_ty(\
960 ccx.tn().types_to_str(&llsig.llarg_tys),
961 ccx.tn().type_to_string(llsig.llret_ty),
962 ccx.tn().types_to_str(&fn_ty.arg_tys.iter().map(|t| t.ty).collect::<Vec<_>>()),
963 ccx.tn().type_to_string(fn_ty.ret_ty.ty),
973 fn lltype_for_fn_from_foreign_types(ccx: &CrateContext, tys: &ForeignTypes) -> Type {
974 let mut llargument_tys = Vec::new();
976 let ret_ty = tys.fn_ty.ret_ty;
977 let llreturn_ty = if ret_ty.is_indirect() {
978 llargument_tys.push(ret_ty.ty.ptr_to());
987 for &arg_ty in &tys.fn_ty.arg_tys {
988 if arg_ty.is_ignore() {
993 Some(ty) => llargument_tys.push(ty),
997 let llarg_ty = if arg_ty.is_indirect() {
1006 llargument_tys.push(llarg_ty);
1009 if tys.fn_sig.variadic {
1010 Type::variadic_func(&llargument_tys, &llreturn_ty)
1012 Type::func(&llargument_tys[..], &llreturn_ty)
1016 pub fn lltype_for_foreign_fn<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
1017 ty: Ty<'tcx>) -> Type {
1018 lltype_for_fn_from_foreign_types(ccx, &foreign_types_for_fn_ty(ccx, ty))
1021 fn add_argument_attributes(tys: &ForeignTypes,
1023 let mut i = if tys.fn_ty.ret_ty.is_indirect() {
1029 match tys.fn_ty.ret_ty.attr {
1030 Some(attr) => unsafe {
1031 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);
1038 for &arg_ty in &tys.fn_ty.arg_tys {
1039 if arg_ty.is_ignore() {
1043 if arg_ty.pad.is_some() { i += 1; }
1046 Some(attr) => unsafe {
1047 llvm::LLVMAddFunctionAttribute(llfn, i as c_uint, attr.bits() as u64);