2 use rustc_hir::lang_items::LangItem;
3 use rustc_middle::ty::layout::{
4 fn_can_unwind, FnAbiError, HasParamEnv, HasTyCtxt, LayoutCx, LayoutOf, TyAndLayout,
6 use rustc_middle::ty::{self, Ty, TyCtxt};
7 use rustc_span::def_id::DefId;
8 use rustc_target::abi::call::{
9 ArgAbi, ArgAttribute, ArgAttributes, ArgExtension, Conv, FnAbi, PassMode, Reg, RegKind,
11 use rustc_target::abi::*;
12 use rustc_target::spec::abi::Abi as SpecAbi;
16 pub fn provide(providers: &mut ty::query::Providers) {
17 *providers = ty::query::Providers { fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
20 // NOTE(eddyb) this is private to avoid using it from outside of
21 // `fn_abi_of_instance` - any other uses are either too high-level
22 // for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
23 // or should go through `FnAbi` instead, to avoid losing any
24 // adjustments `fn_abi_of_instance` might be performing.
25 #[tracing::instrument(level = "debug", skip(tcx, param_env))]
26 fn fn_sig_for_fn_abi<'tcx>(
28 instance: ty::Instance<'tcx>,
29 param_env: ty::ParamEnv<'tcx>,
30 ) -> ty::PolyFnSig<'tcx> {
31 let ty = instance.ty(tcx, param_env);
34 // HACK(davidtwco,eddyb): This is a workaround for polymorphization considering
35 // parameters unused if they show up in the signature, but not in the `mir::Body`
36 // (i.e. due to being inside a projection that got normalized, see
37 // `src/test/ui/polymorphization/normalized_sig_types.rs`), and codegen not keeping
38 // track of a polymorphization `ParamEnv` to allow normalizing later.
40 // We normalize the `fn_sig` again after substituting at a later point.
41 let mut sig = match *ty.kind() {
42 ty::FnDef(def_id, substs) => tcx
45 tcx.normalize_erasing_regions(tcx.param_env(def_id), fn_sig)
51 if let ty::InstanceDef::VTableShim(..) = instance.def {
52 // Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`.
53 sig = sig.map_bound(|mut sig| {
54 let mut inputs_and_output = sig.inputs_and_output.to_vec();
55 inputs_and_output[0] = tcx.mk_mut_ptr(inputs_and_output[0]);
56 sig.inputs_and_output = tcx.intern_type_list(&inputs_and_output);
62 ty::Closure(def_id, substs) => {
63 let sig = substs.as_closure().sig();
65 let bound_vars = tcx.mk_bound_variable_kinds(
66 sig.bound_vars().iter().chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
68 let br = ty::BoundRegion {
69 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
70 kind: ty::BoundRegionKind::BrEnv,
72 let env_region = ty::ReLateBound(ty::INNERMOST, br);
73 let env_ty = tcx.closure_env_ty(def_id, substs, env_region).unwrap();
75 let sig = sig.skip_binder();
76 ty::Binder::bind_with_vars(
78 iter::once(env_ty).chain(sig.inputs().iter().cloned()),
87 ty::Generator(_, substs, _) => {
88 let sig = substs.as_generator().poly_sig();
90 let bound_vars = tcx.mk_bound_variable_kinds(
91 sig.bound_vars().iter().chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
93 let br = ty::BoundRegion {
94 var: ty::BoundVar::from_usize(bound_vars.len() - 1),
95 kind: ty::BoundRegionKind::BrEnv,
97 let env_region = ty::ReLateBound(ty::INNERMOST, br);
98 let env_ty = tcx.mk_mut_ref(tcx.mk_region(env_region), ty);
100 let pin_did = tcx.require_lang_item(LangItem::Pin, None);
101 let pin_adt_ref = tcx.adt_def(pin_did);
102 let pin_substs = tcx.intern_substs(&[env_ty.into()]);
103 let env_ty = tcx.mk_adt(pin_adt_ref, pin_substs);
105 let sig = sig.skip_binder();
106 let state_did = tcx.require_lang_item(LangItem::GeneratorState, None);
107 let state_adt_ref = tcx.adt_def(state_did);
108 let state_substs = tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]);
109 let ret_ty = tcx.mk_adt(state_adt_ref, state_substs);
110 ty::Binder::bind_with_vars(
112 [env_ty, sig.resume_ty].iter(),
115 hir::Unsafety::Normal,
116 rustc_target::spec::abi::Abi::Rust,
121 _ => bug!("unexpected type {:?} in Instance::fn_sig", ty),
126 fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
127 use rustc_target::spec::abi::Abi::*;
128 match tcx.sess.target.adjust_abi(abi) {
129 RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust,
130 RustCold => Conv::RustCold,
132 // It's the ABI's job to select this, not ours.
133 System { .. } => bug!("system abi should be selected elsewhere"),
134 EfiApi => bug!("eficall abi should be selected elsewhere"),
136 Stdcall { .. } => Conv::X86Stdcall,
137 Fastcall { .. } => Conv::X86Fastcall,
138 Vectorcall { .. } => Conv::X86VectorCall,
139 Thiscall { .. } => Conv::X86ThisCall,
141 Unadjusted => Conv::C,
142 Win64 { .. } => Conv::X86_64Win64,
143 SysV64 { .. } => Conv::X86_64SysV,
144 Aapcs { .. } => Conv::ArmAapcs,
145 CCmseNonSecureCall => Conv::CCmseNonSecureCall,
146 PtxKernel => Conv::PtxKernel,
147 Msp430Interrupt => Conv::Msp430Intr,
148 X86Interrupt => Conv::X86Intr,
149 AmdGpuKernel => Conv::AmdGpuKernel,
150 AvrInterrupt => Conv::AvrInterrupt,
151 AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
154 // These API constants ought to be more specific...
155 Cdecl { .. } => Conv::C,
159 fn fn_abi_of_fn_ptr<'tcx>(
161 query: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
162 ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
163 let (param_env, (sig, extra_args)) = query.into_parts();
165 let cx = LayoutCx { tcx, param_env };
166 fn_abi_new_uncached(&cx, sig, extra_args, None, None, false)
169 fn fn_abi_of_instance<'tcx>(
171 query: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
172 ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
173 let (param_env, (instance, extra_args)) = query.into_parts();
175 let sig = fn_sig_for_fn_abi(tcx, instance, param_env);
177 let caller_location = if instance.def.requires_caller_location(tcx) {
178 Some(tcx.caller_location_ty())
184 &LayoutCx { tcx, param_env },
188 Some(instance.def_id()),
189 matches!(instance.def, ty::InstanceDef::Virtual(..)),
193 // Handle safe Rust thin and fat pointers.
194 fn adjust_for_rust_scalar<'tcx>(
195 cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
196 attrs: &mut ArgAttributes,
198 layout: TyAndLayout<'tcx>,
202 // Booleans are always a noundef i1 that needs to be zero-extended.
203 if scalar.is_bool() {
204 attrs.ext(ArgExtension::Zext);
205 attrs.set(ArgAttribute::NoUndef);
209 // Scalars which have invalid values cannot be undef.
210 if !scalar.is_always_valid(&cx) {
211 attrs.set(ArgAttribute::NoUndef);
214 // Only pointer types handled below.
215 let Scalar::Initialized { value: Pointer, valid_range} = scalar else { return };
217 if !valid_range.contains(0) {
218 attrs.set(ArgAttribute::NonNull);
221 if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
222 if let Some(kind) = pointee.safe {
223 attrs.pointee_align = Some(pointee.align);
225 // `Box` (`UniqueBorrowed`) are not necessarily dereferenceable
226 // for the entire duration of the function as they can be deallocated
227 // at any time. Same for shared mutable references. If LLVM had a
228 // way to say "dereferenceable on entry" we could use it here.
229 attrs.pointee_size = match kind {
230 PointerKind::UniqueBorrowed
231 | PointerKind::UniqueBorrowedPinned
232 | PointerKind::Frozen => pointee.size,
233 PointerKind::SharedMutable | PointerKind::UniqueOwned => Size::ZERO,
236 // `Box`, `&T`, and `&mut T` cannot be undef.
237 // Note that this only applies to the value of the pointer itself;
238 // this attribute doesn't make it UB for the pointed-to data to be undef.
239 attrs.set(ArgAttribute::NoUndef);
241 // The aliasing rules for `Box<T>` are still not decided, but currently we emit
242 // `noalias` for it. This can be turned off using an unstable flag.
243 // See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
244 let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias.unwrap_or(true);
246 // `&mut` pointer parameters never alias other parameters,
247 // or mutable global data
249 // `&T` where `T` contains no `UnsafeCell<U>` is immutable,
250 // and can be marked as both `readonly` and `noalias`, as
251 // LLVM's definition of `noalias` is based solely on memory
252 // dependencies rather than pointer equality
254 // Due to past miscompiles in LLVM, we apply a separate NoAliasMutRef attribute
255 // for UniqueBorrowed arguments, so that the codegen backend can decide whether
256 // or not to actually emit the attribute. It can also be controlled with the
257 // `-Zmutable-noalias` debugging option.
258 let no_alias = match kind {
259 PointerKind::SharedMutable
260 | PointerKind::UniqueBorrowed
261 | PointerKind::UniqueBorrowedPinned => false,
262 PointerKind::UniqueOwned => noalias_for_box,
263 PointerKind::Frozen => !is_return,
266 attrs.set(ArgAttribute::NoAlias);
269 if kind == PointerKind::Frozen && !is_return {
270 attrs.set(ArgAttribute::ReadOnly);
273 if kind == PointerKind::UniqueBorrowed && !is_return {
274 attrs.set(ArgAttribute::NoAliasMutRef);
280 // FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
281 // arguments of this method, into a separate `struct`.
282 #[tracing::instrument(level = "debug", skip(cx, caller_location, fn_def_id, force_thin_self_ptr))]
283 fn fn_abi_new_uncached<'tcx>(
284 cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
285 sig: ty::PolyFnSig<'tcx>,
286 extra_args: &[Ty<'tcx>],
287 caller_location: Option<Ty<'tcx>>,
288 fn_def_id: Option<DefId>,
289 // FIXME(eddyb) replace this with something typed, like an `enum`.
290 force_thin_self_ptr: bool,
291 ) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
292 let sig = cx.tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
294 let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
296 let mut inputs = sig.inputs();
297 let extra_args = if sig.abi == RustCall {
298 assert!(!sig.c_variadic && extra_args.is_empty());
300 if let Some(input) = sig.inputs().last() {
301 if let ty::Tuple(tupled_arguments) = input.kind() {
302 inputs = &sig.inputs()[0..sig.inputs().len() - 1];
306 "argument to function with \"rust-call\" ABI \
312 "argument to function with \"rust-call\" ABI \
317 assert!(sig.c_variadic || extra_args.is_empty());
321 let target = &cx.tcx.sess.target;
322 let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl" | "uclibc");
323 let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
324 let linux_s390x_gnu_like =
325 target.os == "linux" && target.arch == "s390x" && target_env_gnu_like;
326 let linux_sparc64_gnu_like =
327 target.os == "linux" && target.arch == "sparc64" && target_env_gnu_like;
328 let linux_powerpc_gnu_like =
329 target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
331 let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
333 let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
334 let span = tracing::debug_span!("arg_of");
335 let _entered = span.enter();
336 let is_return = arg_idx.is_none();
338 let layout = cx.layout_of(ty)?;
339 let layout = if force_thin_self_ptr && arg_idx == Some(0) {
340 // Don't pass the vtable, it's not an argument of the virtual fn.
341 // Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
342 // or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
343 make_thin_self_ptr(cx, layout)
348 let mut arg = ArgAbi::new(cx, layout, |layout, scalar, offset| {
349 let mut attrs = ArgAttributes::new();
350 adjust_for_rust_scalar(*cx, &mut attrs, scalar, *layout, offset, is_return);
354 if arg.layout.is_zst() {
355 // For some forsaken reason, x86_64-pc-windows-gnu
356 // doesn't ignore zero-sized struct arguments.
357 // The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl,uclibc}.
361 && !linux_s390x_gnu_like
362 && !linux_sparc64_gnu_like
363 && !linux_powerpc_gnu_like)
365 arg.mode = PassMode::Ignore;
372 let mut fn_abi = FnAbi {
373 ret: arg_of(sig.output(), None)?,
377 .chain(extra_args.iter().copied())
378 .chain(caller_location)
380 .map(|(i, ty)| arg_of(ty, Some(i)))
381 .collect::<Result<_, _>>()?,
382 c_variadic: sig.c_variadic,
383 fixed_count: inputs.len() as u32,
385 can_unwind: fn_can_unwind(cx.tcx(), fn_def_id, sig.abi),
387 fn_abi_adjust_for_abi(cx, &mut fn_abi, sig.abi)?;
388 debug!("fn_abi_new_uncached = {:?}", fn_abi);
389 Ok(cx.tcx.arena.alloc(fn_abi))
392 #[tracing::instrument(level = "trace", skip(cx))]
393 fn fn_abi_adjust_for_abi<'tcx>(
394 cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
395 fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
397 ) -> Result<(), FnAbiError<'tcx>> {
398 if abi == SpecAbi::Unadjusted {
402 if abi == SpecAbi::Rust
403 || abi == SpecAbi::RustCall
404 || abi == SpecAbi::RustIntrinsic
405 || abi == SpecAbi::PlatformIntrinsic
407 let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>| {
412 match arg.layout.abi {
413 Abi::Aggregate { .. } => {}
415 // This is a fun case! The gist of what this is doing is
416 // that we want callers and callees to always agree on the
417 // ABI of how they pass SIMD arguments. If we were to *not*
418 // make these arguments indirect then they'd be immediates
419 // in LLVM, which means that they'd used whatever the
420 // appropriate ABI is for the callee and the caller. That
421 // means, for example, if the caller doesn't have AVX
422 // enabled but the callee does, then passing an AVX argument
423 // across this boundary would cause corrupt data to show up.
425 // This problem is fixed by unconditionally passing SIMD
426 // arguments through memory between callers and callees
427 // which should get them all to agree on ABI regardless of
428 // target feature sets. Some more information about this
429 // issue can be found in #44367.
431 // Note that the platform intrinsic ABI is exempt here as
432 // that's how we connect up to LLVM and it's unstable
433 // anyway, we control all calls to it in libstd.
435 if abi != SpecAbi::PlatformIntrinsic
436 && cx.tcx.sess.target.simd_types_indirect =>
445 let size = arg.layout.size;
446 if arg.layout.is_unsized() || size > Pointer.size(cx) {
449 // We want to pass small aggregates as immediates, but using
450 // a LLVM aggregate type for this leads to bad optimizations,
451 // so we pick an appropriately sized integer type instead.
452 arg.cast_to(Reg { kind: RegKind::Integer, size });
455 fixup(&mut fn_abi.ret);
456 for arg in fn_abi.args.iter_mut() {
460 fn_abi.adjust_for_foreign_abi(cx, abi)?;
466 #[tracing::instrument(level = "debug", skip(cx))]
467 fn make_thin_self_ptr<'tcx>(
468 cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>),
469 layout: TyAndLayout<'tcx>,
470 ) -> TyAndLayout<'tcx> {
472 let fat_pointer_ty = if layout.is_unsized() {
473 // unsized `self` is passed as a pointer to `self`
474 // FIXME (mikeyhew) change this to use &own if it is ever added to the language
475 tcx.mk_mut_ptr(layout.ty)
478 Abi::ScalarPair(..) | Abi::Scalar(..) => (),
479 _ => bug!("receiver type has unsupported layout: {:?}", layout),
482 // In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
483 // with a Scalar (not ScalarPair) ABI. This is a hack that is understood
484 // elsewhere in the compiler as a method on a `dyn Trait`.
485 // To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
486 // get a built-in pointer type
487 let mut fat_pointer_layout = layout;
488 'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
489 && !fat_pointer_layout.ty.is_region_ptr()
491 for i in 0..fat_pointer_layout.fields.count() {
492 let field_layout = fat_pointer_layout.field(cx, i);
494 if !field_layout.is_zst() {
495 fat_pointer_layout = field_layout;
496 continue 'descend_newtypes;
500 bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
503 fat_pointer_layout.ty
506 // we now have a type like `*mut RcBox<dyn Trait>`
507 // change its layout to that of `*mut ()`, a thin pointer, but keep the same type
508 // this is understood as a special case elsewhere in the compiler
509 let unit_ptr_ty = tcx.mk_mut_ptr(tcx.mk_unit());
514 // NOTE(eddyb) using an empty `ParamEnv`, and `unwrap`-ing the `Result`
515 // should always work because the type is always `*mut ()`.
516 ..tcx.layout_of(ty::ParamEnv::reveal_all().and(unit_ptr_ty)).unwrap()