756 lines
32 KiB
Rust
756 lines
32 KiB
Rust
use rustc_hir as hir;
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use rustc_hir::lang_items::LangItem;
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use rustc_middle::query::Providers;
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use rustc_middle::ty::layout::{
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fn_can_unwind, FnAbiError, HasParamEnv, HasTyCtxt, LayoutCx, LayoutOf, TyAndLayout,
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};
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use rustc_middle::ty::{self, InstanceDef, Ty, TyCtxt};
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use rustc_session::config::OptLevel;
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use rustc_span::def_id::DefId;
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use rustc_target::abi::call::{
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ArgAbi, ArgAttribute, ArgAttributes, ArgExtension, Conv, FnAbi, PassMode, Reg, RegKind,
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RiscvInterruptKind,
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};
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use rustc_target::abi::*;
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use rustc_target::spec::abi::Abi as SpecAbi;
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use std::iter;
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pub(crate) fn provide(providers: &mut Providers) {
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*providers = Providers { fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
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}
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// NOTE(eddyb) this is private to avoid using it from outside of
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// `fn_abi_of_instance` - any other uses are either too high-level
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// for `Instance` (e.g. typeck would use `Ty::fn_sig` instead),
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// or should go through `FnAbi` instead, to avoid losing any
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// adjustments `fn_abi_of_instance` might be performing.
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#[tracing::instrument(level = "debug", skip(tcx, param_env))]
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fn fn_sig_for_fn_abi<'tcx>(
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tcx: TyCtxt<'tcx>,
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instance: ty::Instance<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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) -> ty::PolyFnSig<'tcx> {
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if let InstanceDef::ThreadLocalShim(..) = instance.def {
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return ty::Binder::dummy(tcx.mk_fn_sig(
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[],
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tcx.thread_local_ptr_ty(instance.def_id()),
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false,
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hir::Unsafety::Normal,
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rustc_target::spec::abi::Abi::Unadjusted,
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));
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}
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let ty = instance.ty(tcx, param_env);
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match *ty.kind() {
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ty::FnDef(..) => {
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// HACK(davidtwco,eddyb): This is a workaround for polymorphization considering
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// parameters unused if they show up in the signature, but not in the `mir::Body`
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// (i.e. due to being inside a projection that got normalized, see
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// `tests/ui/polymorphization/normalized_sig_types.rs`), and codegen not keeping
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// track of a polymorphization `ParamEnv` to allow normalizing later.
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//
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// We normalize the `fn_sig` again after substituting at a later point.
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let mut sig = match *ty.kind() {
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ty::FnDef(def_id, args) => tcx
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.fn_sig(def_id)
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.map_bound(|fn_sig| {
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tcx.normalize_erasing_regions(tcx.param_env(def_id), fn_sig)
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})
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.instantiate(tcx, args),
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_ => unreachable!(),
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};
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if let ty::InstanceDef::VTableShim(..) = instance.def {
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// Modify `fn(self, ...)` to `fn(self: *mut Self, ...)`.
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sig = sig.map_bound(|mut sig| {
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let mut inputs_and_output = sig.inputs_and_output.to_vec();
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inputs_and_output[0] = Ty::new_mut_ptr(tcx, inputs_and_output[0]);
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sig.inputs_and_output = tcx.mk_type_list(&inputs_and_output);
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sig
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});
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}
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sig
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}
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ty::Closure(def_id, args) => {
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let sig = args.as_closure().sig();
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let bound_vars = tcx.mk_bound_variable_kinds_from_iter(
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sig.bound_vars().iter().chain(iter::once(ty::BoundVariableKind::Region(ty::BrEnv))),
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);
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let br = ty::BoundRegion {
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var: ty::BoundVar::from_usize(bound_vars.len() - 1),
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kind: ty::BoundRegionKind::BrEnv,
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};
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let env_region = ty::Region::new_bound(tcx, ty::INNERMOST, br);
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let env_ty = tcx.closure_env_ty(def_id, args, env_region).unwrap();
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let sig = sig.skip_binder();
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ty::Binder::bind_with_vars(
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tcx.mk_fn_sig(
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iter::once(env_ty).chain(sig.inputs().iter().cloned()),
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sig.output(),
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sig.c_variadic,
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sig.unsafety,
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sig.abi,
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),
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bound_vars,
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)
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}
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ty::Coroutine(did, args, _) => {
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let coroutine_kind = tcx.coroutine_kind(did).unwrap();
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let sig = args.as_coroutine().sig();
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let bound_vars = tcx.mk_bound_variable_kinds_from_iter(iter::once(
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ty::BoundVariableKind::Region(ty::BrEnv),
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));
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let br = ty::BoundRegion {
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var: ty::BoundVar::from_usize(bound_vars.len() - 1),
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kind: ty::BoundRegionKind::BrEnv,
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};
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let env_ty = Ty::new_mut_ref(tcx, ty::Region::new_bound(tcx, ty::INNERMOST, br), ty);
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let pin_did = tcx.require_lang_item(LangItem::Pin, None);
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let pin_adt_ref = tcx.adt_def(pin_did);
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let pin_args = tcx.mk_args(&[env_ty.into()]);
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let env_ty = match coroutine_kind {
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hir::CoroutineKind::Gen(_) => {
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// Iterator::next doesn't accept a pinned argument,
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// unlike for all other coroutine kinds.
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env_ty
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}
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hir::CoroutineKind::Async(_) | hir::CoroutineKind::Coroutine => {
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Ty::new_adt(tcx, pin_adt_ref, pin_args)
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}
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};
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// The `FnSig` and the `ret_ty` here is for a coroutines main
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// `Coroutine::resume(...) -> CoroutineState` function in case we
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// have an ordinary coroutine, the `Future::poll(...) -> Poll`
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// function in case this is a special coroutine backing an async construct
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// or the `Iterator::next(...) -> Option` function in case this is a
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// special coroutine backing a gen construct.
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let (resume_ty, ret_ty) = match coroutine_kind {
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hir::CoroutineKind::Async(_) => {
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// The signature should be `Future::poll(_, &mut Context<'_>) -> Poll<Output>`
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assert_eq!(sig.yield_ty, tcx.types.unit);
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let poll_did = tcx.require_lang_item(LangItem::Poll, None);
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let poll_adt_ref = tcx.adt_def(poll_did);
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let poll_args = tcx.mk_args(&[sig.return_ty.into()]);
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let ret_ty = Ty::new_adt(tcx, poll_adt_ref, poll_args);
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// We have to replace the `ResumeTy` that is used for type and borrow checking
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// with `&mut Context<'_>` which is used in codegen.
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#[cfg(debug_assertions)]
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{
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if let ty::Adt(resume_ty_adt, _) = sig.resume_ty.kind() {
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let expected_adt =
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tcx.adt_def(tcx.require_lang_item(LangItem::ResumeTy, None));
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assert_eq!(*resume_ty_adt, expected_adt);
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} else {
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panic!("expected `ResumeTy`, found `{:?}`", sig.resume_ty);
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};
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}
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let context_mut_ref = Ty::new_task_context(tcx);
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(Some(context_mut_ref), ret_ty)
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}
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hir::CoroutineKind::Gen(_) => {
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// The signature should be `Iterator::next(_) -> Option<Yield>`
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let option_did = tcx.require_lang_item(LangItem::Option, None);
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let option_adt_ref = tcx.adt_def(option_did);
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let option_args = tcx.mk_args(&[sig.yield_ty.into()]);
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let ret_ty = Ty::new_adt(tcx, option_adt_ref, option_args);
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assert_eq!(sig.return_ty, tcx.types.unit);
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assert_eq!(sig.resume_ty, tcx.types.unit);
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(None, ret_ty)
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}
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hir::CoroutineKind::Coroutine => {
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// The signature should be `Coroutine::resume(_, Resume) -> CoroutineState<Yield, Return>`
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let state_did = tcx.require_lang_item(LangItem::CoroutineState, None);
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let state_adt_ref = tcx.adt_def(state_did);
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let state_args = tcx.mk_args(&[sig.yield_ty.into(), sig.return_ty.into()]);
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let ret_ty = Ty::new_adt(tcx, state_adt_ref, state_args);
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(Some(sig.resume_ty), ret_ty)
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}
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};
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let fn_sig = if let Some(resume_ty) = resume_ty {
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tcx.mk_fn_sig(
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[env_ty, resume_ty],
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ret_ty,
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false,
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hir::Unsafety::Normal,
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rustc_target::spec::abi::Abi::Rust,
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)
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} else {
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// `Iterator::next` doesn't have a `resume` argument.
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tcx.mk_fn_sig(
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[env_ty],
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ret_ty,
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false,
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hir::Unsafety::Normal,
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rustc_target::spec::abi::Abi::Rust,
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)
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};
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ty::Binder::bind_with_vars(fn_sig, bound_vars)
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}
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_ => bug!("unexpected type {:?} in Instance::fn_sig", ty),
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}
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}
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#[inline]
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fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
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use rustc_target::spec::abi::Abi::*;
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match tcx.sess.target.adjust_abi(abi) {
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RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::Rust,
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// This is intentionally not using `Conv::Cold`, as that has to preserve
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// even SIMD registers, which is generally not a good trade-off.
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RustCold => Conv::PreserveMost,
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// It's the ABI's job to select this, not ours.
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System { .. } => bug!("system abi should be selected elsewhere"),
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EfiApi => bug!("eficall abi should be selected elsewhere"),
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Stdcall { .. } => Conv::X86Stdcall,
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Fastcall { .. } => Conv::X86Fastcall,
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Vectorcall { .. } => Conv::X86VectorCall,
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Thiscall { .. } => Conv::X86ThisCall,
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C { .. } => Conv::C,
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Unadjusted => Conv::C,
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Win64 { .. } => Conv::X86_64Win64,
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SysV64 { .. } => Conv::X86_64SysV,
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Aapcs { .. } => Conv::ArmAapcs,
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CCmseNonSecureCall => Conv::CCmseNonSecureCall,
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PtxKernel => Conv::PtxKernel,
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Msp430Interrupt => Conv::Msp430Intr,
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X86Interrupt => Conv::X86Intr,
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AmdGpuKernel => Conv::AmdGpuKernel,
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AvrInterrupt => Conv::AvrInterrupt,
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AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
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RiscvInterruptM => Conv::RiscvInterrupt { kind: RiscvInterruptKind::Machine },
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RiscvInterruptS => Conv::RiscvInterrupt { kind: RiscvInterruptKind::Supervisor },
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Wasm => Conv::C,
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// These API constants ought to be more specific...
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Cdecl { .. } => Conv::C,
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}
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}
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fn fn_abi_of_fn_ptr<'tcx>(
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tcx: TyCtxt<'tcx>,
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query: ty::ParamEnvAnd<'tcx, (ty::PolyFnSig<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
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) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, &'tcx FnAbiError<'tcx>> {
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let (param_env, (sig, extra_args)) = query.into_parts();
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let cx = LayoutCx { tcx, param_env };
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fn_abi_new_uncached(&cx, sig, extra_args, None, None, false)
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}
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fn fn_abi_of_instance<'tcx>(
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tcx: TyCtxt<'tcx>,
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query: ty::ParamEnvAnd<'tcx, (ty::Instance<'tcx>, &'tcx ty::List<Ty<'tcx>>)>,
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) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, &'tcx FnAbiError<'tcx>> {
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let (param_env, (instance, extra_args)) = query.into_parts();
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let sig = fn_sig_for_fn_abi(tcx, instance, param_env);
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let caller_location =
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instance.def.requires_caller_location(tcx).then(|| tcx.caller_location_ty());
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fn_abi_new_uncached(
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&LayoutCx { tcx, param_env },
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sig,
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extra_args,
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caller_location,
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Some(instance.def_id()),
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matches!(instance.def, ty::InstanceDef::Virtual(..)),
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)
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}
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// Handle safe Rust thin and fat pointers.
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fn adjust_for_rust_scalar<'tcx>(
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cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
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attrs: &mut ArgAttributes,
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scalar: Scalar,
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layout: TyAndLayout<'tcx>,
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offset: Size,
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is_return: bool,
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drop_target_pointee: Option<Ty<'tcx>>,
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) {
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// Booleans are always a noundef i1 that needs to be zero-extended.
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if scalar.is_bool() {
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attrs.ext(ArgExtension::Zext);
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attrs.set(ArgAttribute::NoUndef);
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return;
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}
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if !scalar.is_uninit_valid() {
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attrs.set(ArgAttribute::NoUndef);
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}
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// Only pointer types handled below.
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let Scalar::Initialized { value: Pointer(_), valid_range } = scalar else { return };
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// Set `nonnull` if the validity range excludes zero, or for the argument to `drop_in_place`,
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// which must be nonnull per its documented safety requirements.
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if !valid_range.contains(0) || drop_target_pointee.is_some() {
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attrs.set(ArgAttribute::NonNull);
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}
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if let Some(pointee) = layout.pointee_info_at(&cx, offset) {
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let kind = if let Some(kind) = pointee.safe {
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Some(kind)
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} else if let Some(pointee) = drop_target_pointee {
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// The argument to `drop_in_place` is semantically equivalent to a mutable reference.
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Some(PointerKind::MutableRef { unpin: pointee.is_unpin(cx.tcx, cx.param_env()) })
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} else {
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None
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};
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if let Some(kind) = kind {
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attrs.pointee_align = Some(pointee.align);
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// `Box` are not necessarily dereferenceable for the entire duration of the function as
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// they can be deallocated at any time. Same for non-frozen shared references (see
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// <https://github.com/rust-lang/rust/pull/98017>), and for mutable references to
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// potentially self-referential types (see
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// <https://github.com/rust-lang/unsafe-code-guidelines/issues/381>). If LLVM had a way
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// to say "dereferenceable on entry" we could use it here.
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attrs.pointee_size = match kind {
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PointerKind::Box { .. }
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| PointerKind::SharedRef { frozen: false }
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| PointerKind::MutableRef { unpin: false } => Size::ZERO,
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PointerKind::SharedRef { frozen: true }
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| PointerKind::MutableRef { unpin: true } => pointee.size,
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};
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// The aliasing rules for `Box<T>` are still not decided, but currently we emit
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// `noalias` for it. This can be turned off using an unstable flag.
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// See https://github.com/rust-lang/unsafe-code-guidelines/issues/326
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let noalias_for_box = cx.tcx.sess.opts.unstable_opts.box_noalias;
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// LLVM prior to version 12 had known miscompiles in the presence of noalias attributes
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// (see #54878), so it was conditionally disabled, but we don't support earlier
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// versions at all anymore. We still support turning it off using -Zmutable-noalias.
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let noalias_mut_ref = cx.tcx.sess.opts.unstable_opts.mutable_noalias;
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// `&T` where `T` contains no `UnsafeCell<U>` is immutable, and can be marked as both
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// `readonly` and `noalias`, as LLVM's definition of `noalias` is based solely on memory
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// dependencies rather than pointer equality. However this only applies to arguments,
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// not return values.
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//
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// `&mut T` and `Box<T>` where `T: Unpin` are unique and hence `noalias`.
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let no_alias = match kind {
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PointerKind::SharedRef { frozen } => frozen,
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PointerKind::MutableRef { unpin } => unpin && noalias_mut_ref,
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PointerKind::Box { unpin } => unpin && noalias_for_box,
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};
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// We can never add `noalias` in return position; that LLVM attribute has some very surprising semantics
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// (see <https://github.com/rust-lang/unsafe-code-guidelines/issues/385#issuecomment-1368055745>).
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if no_alias && !is_return {
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attrs.set(ArgAttribute::NoAlias);
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}
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if matches!(kind, PointerKind::SharedRef { frozen: true }) && !is_return {
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attrs.set(ArgAttribute::ReadOnly);
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}
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}
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}
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}
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/// Ensure that the ABI makes basic sense.
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fn fn_abi_sanity_check<'tcx>(
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cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
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fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
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spec_abi: SpecAbi,
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) {
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fn fn_arg_sanity_check<'tcx>(
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cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
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fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
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spec_abi: SpecAbi,
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arg: &ArgAbi<'tcx, Ty<'tcx>>,
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) {
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match &arg.mode {
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PassMode::Ignore => {}
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PassMode::Direct(_) => {
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// Here the Rust type is used to determine the actual ABI, so we have to be very
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// careful. Scalar/ScalarPair is fine, since backends will generally use
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// `layout.abi` and ignore everything else. We should just reject `Aggregate`
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// entirely here, but some targets need to be fixed first.
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if matches!(arg.layout.abi, Abi::Aggregate { .. }) {
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// For an unsized type we'd only pass the sized prefix, so there is no universe
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// in which we ever want to allow this.
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assert!(
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arg.layout.is_sized(),
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"`PassMode::Direct` for unsized type in ABI: {:#?}",
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fn_abi
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);
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// This really shouldn't happen even for sized aggregates, since
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// `immediate_llvm_type` will use `layout.fields` to turn this Rust type into an
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// LLVM type. This means all sorts of Rust type details leak into the ABI.
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// However wasm sadly *does* currently use this mode so we have to allow it --
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// but we absolutely shouldn't let any more targets do that.
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// (Also see <https://github.com/rust-lang/rust/issues/115666>.)
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//
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// The unstable abi `PtxKernel` also uses Direct for now.
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// It needs to switch to something else before stabilization can happen.
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// (See issue: https://github.com/rust-lang/rust/issues/117271)
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assert!(
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matches!(&*cx.tcx.sess.target.arch, "wasm32" | "wasm64")
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|| matches!(spec_abi, SpecAbi::PtxKernel | SpecAbi::Unadjusted),
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r#"`PassMode::Direct` for aggregates only allowed for "unadjusted" and "ptx-kernel" functions and on wasm\nProblematic type: {:#?}"#,
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arg.layout,
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);
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}
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}
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PassMode::Pair(_, _) => {
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// Similar to `Direct`, we need to make sure that backends use `layout.abi` and
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// ignore the rest of the layout.
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assert!(
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matches!(arg.layout.abi, Abi::ScalarPair(..)),
|
|
"PassMode::Pair for type {}",
|
|
arg.layout.ty
|
|
);
|
|
}
|
|
PassMode::Cast { .. } => {
|
|
// `Cast` means "transmute to `CastType`"; that only makes sense for sized types.
|
|
assert!(arg.layout.is_sized());
|
|
}
|
|
PassMode::Indirect { meta_attrs: None, .. } => {
|
|
// No metadata, must be sized.
|
|
// Conceptually, unsized arguments must be copied around, which requires dynamically
|
|
// determining their size, which we cannot do without metadata. Consult
|
|
// t-opsem before removing this check.
|
|
assert!(arg.layout.is_sized());
|
|
}
|
|
PassMode::Indirect { meta_attrs: Some(_), on_stack, .. } => {
|
|
// With metadata. Must be unsized and not on the stack.
|
|
assert!(arg.layout.is_unsized() && !on_stack);
|
|
// Also, must not be `extern` type.
|
|
let tail = cx.tcx.struct_tail_with_normalize(arg.layout.ty, |ty| ty, || {});
|
|
if matches!(tail.kind(), ty::Foreign(..)) {
|
|
// These types do not have metadata, so having `meta_attrs` is bogus.
|
|
// Conceptually, unsized arguments must be copied around, which requires dynamically
|
|
// determining their size. Therefore, we cannot allow `extern` types here. Consult
|
|
// t-opsem before removing this check.
|
|
panic!("unsized arguments must not be `extern` types");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
for arg in fn_abi.args.iter() {
|
|
fn_arg_sanity_check(cx, fn_abi, spec_abi, arg);
|
|
}
|
|
fn_arg_sanity_check(cx, fn_abi, spec_abi, &fn_abi.ret);
|
|
}
|
|
|
|
// FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
|
|
// arguments of this method, into a separate `struct`.
|
|
#[tracing::instrument(level = "debug", skip(cx, caller_location, fn_def_id, force_thin_self_ptr))]
|
|
fn fn_abi_new_uncached<'tcx>(
|
|
cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
|
|
sig: ty::PolyFnSig<'tcx>,
|
|
extra_args: &[Ty<'tcx>],
|
|
caller_location: Option<Ty<'tcx>>,
|
|
fn_def_id: Option<DefId>,
|
|
// FIXME(eddyb) replace this with something typed, like an `enum`.
|
|
force_thin_self_ptr: bool,
|
|
) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, &'tcx FnAbiError<'tcx>> {
|
|
let sig = cx.tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
|
|
|
|
let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
|
|
|
|
let mut inputs = sig.inputs();
|
|
let extra_args = if sig.abi == RustCall {
|
|
assert!(!sig.c_variadic && extra_args.is_empty());
|
|
|
|
if let Some(input) = sig.inputs().last() {
|
|
if let ty::Tuple(tupled_arguments) = input.kind() {
|
|
inputs = &sig.inputs()[0..sig.inputs().len() - 1];
|
|
tupled_arguments
|
|
} else {
|
|
bug!(
|
|
"argument to function with \"rust-call\" ABI \
|
|
is not a tuple"
|
|
);
|
|
}
|
|
} else {
|
|
bug!(
|
|
"argument to function with \"rust-call\" ABI \
|
|
is not a tuple"
|
|
);
|
|
}
|
|
} else {
|
|
assert!(sig.c_variadic || extra_args.is_empty());
|
|
extra_args
|
|
};
|
|
|
|
let target = &cx.tcx.sess.target;
|
|
let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl" | "uclibc");
|
|
let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
|
|
let linux_s390x_gnu_like =
|
|
target.os == "linux" && target.arch == "s390x" && target_env_gnu_like;
|
|
let linux_sparc64_gnu_like =
|
|
target.os == "linux" && target.arch == "sparc64" && target_env_gnu_like;
|
|
let linux_powerpc_gnu_like =
|
|
target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
|
|
use SpecAbi::*;
|
|
let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
|
|
|
|
let is_drop_in_place =
|
|
fn_def_id.is_some() && fn_def_id == cx.tcx.lang_items().drop_in_place_fn();
|
|
|
|
let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, &'tcx FnAbiError<'tcx>> {
|
|
let span = tracing::debug_span!("arg_of");
|
|
let _entered = span.enter();
|
|
let is_return = arg_idx.is_none();
|
|
let is_drop_target = is_drop_in_place && arg_idx == Some(0);
|
|
let drop_target_pointee = is_drop_target.then(|| match ty.kind() {
|
|
ty::RawPtr(ty::TypeAndMut { ty, .. }) => *ty,
|
|
_ => bug!("argument to drop_in_place is not a raw ptr: {:?}", ty),
|
|
});
|
|
|
|
let layout =
|
|
cx.layout_of(ty).map_err(|err| &*cx.tcx.arena.alloc(FnAbiError::Layout(*err)))?;
|
|
let layout = if force_thin_self_ptr && arg_idx == Some(0) {
|
|
// Don't pass the vtable, it's not an argument of the virtual fn.
|
|
// Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
|
|
// or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
|
|
make_thin_self_ptr(cx, layout)
|
|
} else {
|
|
layout
|
|
};
|
|
|
|
let mut arg = ArgAbi::new(cx, layout, |layout, scalar, offset| {
|
|
let mut attrs = ArgAttributes::new();
|
|
adjust_for_rust_scalar(
|
|
*cx,
|
|
&mut attrs,
|
|
scalar,
|
|
*layout,
|
|
offset,
|
|
is_return,
|
|
drop_target_pointee,
|
|
);
|
|
attrs
|
|
});
|
|
|
|
if arg.layout.is_zst() {
|
|
// For some forsaken reason, x86_64-pc-windows-gnu
|
|
// doesn't ignore zero-sized struct arguments.
|
|
// The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl,uclibc}.
|
|
if is_return
|
|
|| rust_abi
|
|
|| (!win_x64_gnu
|
|
&& !linux_s390x_gnu_like
|
|
&& !linux_sparc64_gnu_like
|
|
&& !linux_powerpc_gnu_like)
|
|
{
|
|
arg.mode = PassMode::Ignore;
|
|
}
|
|
}
|
|
|
|
Ok(arg)
|
|
};
|
|
|
|
let mut fn_abi = FnAbi {
|
|
ret: arg_of(sig.output(), None)?,
|
|
args: inputs
|
|
.iter()
|
|
.copied()
|
|
.chain(extra_args.iter().copied())
|
|
.chain(caller_location)
|
|
.enumerate()
|
|
.map(|(i, ty)| arg_of(ty, Some(i)))
|
|
.collect::<Result<_, _>>()?,
|
|
c_variadic: sig.c_variadic,
|
|
fixed_count: inputs.len() as u32,
|
|
conv,
|
|
can_unwind: fn_can_unwind(cx.tcx(), fn_def_id, sig.abi),
|
|
};
|
|
fn_abi_adjust_for_abi(cx, &mut fn_abi, sig.abi, fn_def_id)?;
|
|
debug!("fn_abi_new_uncached = {:?}", fn_abi);
|
|
fn_abi_sanity_check(cx, &fn_abi, sig.abi);
|
|
Ok(cx.tcx.arena.alloc(fn_abi))
|
|
}
|
|
|
|
#[tracing::instrument(level = "trace", skip(cx))]
|
|
fn fn_abi_adjust_for_abi<'tcx>(
|
|
cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
|
|
fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
|
|
abi: SpecAbi,
|
|
fn_def_id: Option<DefId>,
|
|
) -> Result<(), &'tcx FnAbiError<'tcx>> {
|
|
if abi == SpecAbi::Unadjusted {
|
|
// The "unadjusted" ABI passes aggregates in "direct" mode. That's fragile but needed for
|
|
// some LLVM intrinsics.
|
|
fn unadjust<'tcx>(arg: &mut ArgAbi<'tcx, Ty<'tcx>>) {
|
|
// This still uses `PassMode::Pair` for ScalarPair types. That's unlikely to be intended,
|
|
// but who knows what breaks if we change this now.
|
|
if matches!(arg.layout.abi, Abi::Aggregate { .. }) {
|
|
assert!(
|
|
arg.layout.abi.is_sized(),
|
|
"'unadjusted' ABI does not support unsized arguments"
|
|
);
|
|
}
|
|
arg.make_direct_deprecated();
|
|
}
|
|
|
|
unadjust(&mut fn_abi.ret);
|
|
for arg in fn_abi.args.iter_mut() {
|
|
unadjust(arg);
|
|
}
|
|
return Ok(());
|
|
}
|
|
|
|
if abi == SpecAbi::Rust
|
|
|| abi == SpecAbi::RustCall
|
|
|| abi == SpecAbi::RustIntrinsic
|
|
|| abi == SpecAbi::PlatformIntrinsic
|
|
{
|
|
// Look up the deduced parameter attributes for this function, if we have its def ID and
|
|
// we're optimizing in non-incremental mode. We'll tag its parameters with those attributes
|
|
// as appropriate.
|
|
let deduced_param_attrs = if cx.tcx.sess.opts.optimize != OptLevel::No
|
|
&& cx.tcx.sess.opts.incremental.is_none()
|
|
{
|
|
fn_def_id.map(|fn_def_id| cx.tcx.deduced_param_attrs(fn_def_id)).unwrap_or_default()
|
|
} else {
|
|
&[]
|
|
};
|
|
|
|
let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>, arg_idx: Option<usize>| {
|
|
if arg.is_ignore() {
|
|
return;
|
|
}
|
|
|
|
match arg.layout.abi {
|
|
Abi::Aggregate { .. } => {}
|
|
|
|
// This is a fun case! The gist of what this is doing is
|
|
// that we want callers and callees to always agree on the
|
|
// ABI of how they pass SIMD arguments. If we were to *not*
|
|
// make these arguments indirect then they'd be immediates
|
|
// in LLVM, which means that they'd used whatever the
|
|
// appropriate ABI is for the callee and the caller. That
|
|
// means, for example, if the caller doesn't have AVX
|
|
// enabled but the callee does, then passing an AVX argument
|
|
// across this boundary would cause corrupt data to show up.
|
|
//
|
|
// This problem is fixed by unconditionally passing SIMD
|
|
// arguments through memory between callers and callees
|
|
// which should get them all to agree on ABI regardless of
|
|
// target feature sets. Some more information about this
|
|
// issue can be found in #44367.
|
|
//
|
|
// Note that the platform intrinsic ABI is exempt here as
|
|
// that's how we connect up to LLVM and it's unstable
|
|
// anyway, we control all calls to it in libstd.
|
|
Abi::Vector { .. }
|
|
if abi != SpecAbi::PlatformIntrinsic
|
|
&& cx.tcx.sess.target.simd_types_indirect =>
|
|
{
|
|
arg.make_indirect();
|
|
return;
|
|
}
|
|
|
|
_ => return,
|
|
}
|
|
// Compute `Aggregate` ABI.
|
|
|
|
let is_indirect_not_on_stack =
|
|
matches!(arg.mode, PassMode::Indirect { on_stack: false, .. });
|
|
assert!(is_indirect_not_on_stack, "{:?}", arg);
|
|
|
|
let size = arg.layout.size;
|
|
if !arg.layout.is_unsized() && size <= Pointer(AddressSpace::DATA).size(cx) {
|
|
// We want to pass small aggregates as immediates, but using
|
|
// an LLVM aggregate type for this leads to bad optimizations,
|
|
// so we pick an appropriately sized integer type instead.
|
|
arg.cast_to(Reg { kind: RegKind::Integer, size });
|
|
}
|
|
|
|
// If we deduced that this parameter was read-only, add that to the attribute list now.
|
|
//
|
|
// The `readonly` parameter only applies to pointers, so we can only do this if the
|
|
// argument was passed indirectly. (If the argument is passed directly, it's an SSA
|
|
// value, so it's implicitly immutable.)
|
|
if let (Some(arg_idx), &mut PassMode::Indirect { ref mut attrs, .. }) =
|
|
(arg_idx, &mut arg.mode)
|
|
{
|
|
// The `deduced_param_attrs` list could be empty if this is a type of function
|
|
// we can't deduce any parameters for, so make sure the argument index is in
|
|
// bounds.
|
|
if let Some(deduced_param_attrs) = deduced_param_attrs.get(arg_idx) {
|
|
if deduced_param_attrs.read_only {
|
|
attrs.regular.insert(ArgAttribute::ReadOnly);
|
|
debug!("added deduced read-only attribute");
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
fixup(&mut fn_abi.ret, None);
|
|
for (arg_idx, arg) in fn_abi.args.iter_mut().enumerate() {
|
|
fixup(arg, Some(arg_idx));
|
|
}
|
|
} else {
|
|
fn_abi
|
|
.adjust_for_foreign_abi(cx, abi)
|
|
.map_err(|err| &*cx.tcx.arena.alloc(FnAbiError::AdjustForForeignAbi(err)))?;
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
#[tracing::instrument(level = "debug", skip(cx))]
|
|
fn make_thin_self_ptr<'tcx>(
|
|
cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>),
|
|
layout: TyAndLayout<'tcx>,
|
|
) -> TyAndLayout<'tcx> {
|
|
let tcx = cx.tcx();
|
|
let fat_pointer_ty = if layout.is_unsized() {
|
|
// unsized `self` is passed as a pointer to `self`
|
|
// FIXME (mikeyhew) change this to use &own if it is ever added to the language
|
|
Ty::new_mut_ptr(tcx, layout.ty)
|
|
} else {
|
|
match layout.abi {
|
|
Abi::ScalarPair(..) | Abi::Scalar(..) => (),
|
|
_ => bug!("receiver type has unsupported layout: {:?}", layout),
|
|
}
|
|
|
|
// In the case of Rc<Self>, we need to explicitly pass a *mut RcBox<Self>
|
|
// with a Scalar (not ScalarPair) ABI. This is a hack that is understood
|
|
// elsewhere in the compiler as a method on a `dyn Trait`.
|
|
// To get the type `*mut RcBox<Self>`, we just keep unwrapping newtypes until we
|
|
// get a built-in pointer type
|
|
let mut fat_pointer_layout = layout;
|
|
while !fat_pointer_layout.ty.is_unsafe_ptr() && !fat_pointer_layout.ty.is_ref() {
|
|
fat_pointer_layout = fat_pointer_layout
|
|
.non_1zst_field(cx)
|
|
.expect("not exactly one non-1-ZST field in a `DispatchFromDyn` type")
|
|
.1
|
|
}
|
|
|
|
fat_pointer_layout.ty
|
|
};
|
|
|
|
// we now have a type like `*mut RcBox<dyn Trait>`
|
|
// change its layout to that of `*mut ()`, a thin pointer, but keep the same type
|
|
// this is understood as a special case elsewhere in the compiler
|
|
let unit_ptr_ty = Ty::new_mut_ptr(tcx, Ty::new_unit(tcx));
|
|
|
|
TyAndLayout {
|
|
ty: fat_pointer_ty,
|
|
|
|
// NOTE(eddyb) using an empty `ParamEnv`, and `unwrap`-ing the `Result`
|
|
// should always work because the type is always `*mut ()`.
|
|
..tcx.layout_of(ty::ParamEnv::reveal_all().and(unit_ptr_ty)).unwrap()
|
|
}
|
|
}
|