9a7cc6c32f
Rollup of 7 pull requests Successful merges: - #106347 (More accurate spans for arg removal suggestion) - #108057 (Prevent some attributes from being merged with others on reexports) - #108090 (`if $c:expr { Some($r:expr) } else { None }` =>> `$c.then(|| $r)`) - #108092 (note issue for feature(packed_bundled_libs)) - #108099 (use chars instead of strings where applicable) - #108115 (Do not ICE on unmet trait alias bounds) - #108125 (Add new people to the compiletest review rotation) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
572 lines
24 KiB
Rust
572 lines
24 KiB
Rust
use rustc_hir as hir;
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use rustc_hir::lang_items::LangItem;
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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, 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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};
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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 fn provide(providers: &mut ty::query::Providers) {
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*providers = ty::query::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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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, substs) => 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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.subst(tcx, substs),
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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] = tcx.mk_mut_ptr(inputs_and_output[0]);
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sig.inputs_and_output = tcx.intern_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, substs) => {
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let sig = substs.as_closure().sig();
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let bound_vars = tcx.mk_bound_variable_kinds(
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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 = tcx.mk_re_late_bound(ty::INNERMOST, br);
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let env_ty = tcx.closure_env_ty(def_id, substs, 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::Generator(did, substs, _) => {
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let sig = substs.as_generator().poly_sig();
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let bound_vars = tcx.mk_bound_variable_kinds(
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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_ty = tcx.mk_mut_ref(tcx.mk_re_late_bound(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_substs = tcx.intern_substs(&[env_ty.into()]);
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let env_ty = tcx.mk_adt(pin_adt_ref, pin_substs);
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let sig = sig.skip_binder();
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// The `FnSig` and the `ret_ty` here is for a generators main
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// `Generator::resume(...) -> GeneratorState` function in case we
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// have an ordinary generator, or the `Future::poll(...) -> Poll`
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// function in case this is a special generator backing an async construct.
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let (resume_ty, ret_ty) = if tcx.generator_is_async(did) {
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// The signature should be `Future::poll(_, &mut Context<'_>) -> Poll<Output>`
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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_substs = tcx.intern_substs(&[sig.return_ty.into()]);
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let ret_ty = tcx.mk_adt(poll_adt_ref, poll_substs);
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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 = tcx.mk_task_context();
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(context_mut_ref, ret_ty)
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} else {
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// The signature should be `Generator::resume(_, Resume) -> GeneratorState<Yield, Return>`
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let state_did = tcx.require_lang_item(LangItem::GeneratorState, None);
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let state_adt_ref = tcx.adt_def(state_did);
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let state_substs = tcx.intern_substs(&[sig.yield_ty.into(), sig.return_ty.into()]);
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let ret_ty = tcx.mk_adt(state_adt_ref, state_substs);
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(sig.resume_ty, ret_ty)
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};
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ty::Binder::bind_with_vars(
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tcx.mk_fn_sig(
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[env_ty, resume_ty].iter(),
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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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bound_vars,
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)
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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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RustCold => Conv::RustCold,
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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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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>>, 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>>, 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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) {
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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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if !valid_range.contains(0) {
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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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if let Some(kind) = pointee.safe {
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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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// FIXME(eddyb) perhaps group the signature/type-containing (or all of them?)
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// arguments of this method, into a separate `struct`.
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#[tracing::instrument(level = "debug", skip(cx, caller_location, fn_def_id, force_thin_self_ptr))]
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fn fn_abi_new_uncached<'tcx>(
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cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
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sig: ty::PolyFnSig<'tcx>,
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extra_args: &[Ty<'tcx>],
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caller_location: Option<Ty<'tcx>>,
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fn_def_id: Option<DefId>,
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// FIXME(eddyb) replace this with something typed, like an `enum`.
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force_thin_self_ptr: bool,
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) -> Result<&'tcx FnAbi<'tcx, Ty<'tcx>>, FnAbiError<'tcx>> {
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let sig = cx.tcx.normalize_erasing_late_bound_regions(cx.param_env, sig);
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let conv = conv_from_spec_abi(cx.tcx(), sig.abi);
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let mut inputs = sig.inputs();
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let extra_args = if sig.abi == RustCall {
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assert!(!sig.c_variadic && extra_args.is_empty());
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if let Some(input) = sig.inputs().last() {
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if let ty::Tuple(tupled_arguments) = input.kind() {
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inputs = &sig.inputs()[0..sig.inputs().len() - 1];
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tupled_arguments
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} else {
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bug!(
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"argument to function with \"rust-call\" ABI \
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is not a tuple"
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);
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}
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} else {
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bug!(
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"argument to function with \"rust-call\" ABI \
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is not a tuple"
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);
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}
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} else {
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assert!(sig.c_variadic || extra_args.is_empty());
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extra_args
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};
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let target = &cx.tcx.sess.target;
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let target_env_gnu_like = matches!(&target.env[..], "gnu" | "musl" | "uclibc");
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let win_x64_gnu = target.os == "windows" && target.arch == "x86_64" && target.env == "gnu";
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let linux_s390x_gnu_like =
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target.os == "linux" && target.arch == "s390x" && target_env_gnu_like;
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let linux_sparc64_gnu_like =
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target.os == "linux" && target.arch == "sparc64" && target_env_gnu_like;
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let linux_powerpc_gnu_like =
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target.os == "linux" && target.arch == "powerpc" && target_env_gnu_like;
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use SpecAbi::*;
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let rust_abi = matches!(sig.abi, RustIntrinsic | PlatformIntrinsic | Rust | RustCall);
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let arg_of = |ty: Ty<'tcx>, arg_idx: Option<usize>| -> Result<_, FnAbiError<'tcx>> {
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let span = tracing::debug_span!("arg_of");
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let _entered = span.enter();
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let is_return = arg_idx.is_none();
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let layout = cx.layout_of(ty)?;
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let layout = if force_thin_self_ptr && arg_idx == Some(0) {
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// Don't pass the vtable, it's not an argument of the virtual fn.
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// Instead, pass just the data pointer, but give it the type `*const/mut dyn Trait`
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// or `&/&mut dyn Trait` because this is special-cased elsewhere in codegen
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make_thin_self_ptr(cx, layout)
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} else {
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layout
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};
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let mut arg = ArgAbi::new(cx, layout, |layout, scalar, offset| {
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let mut attrs = ArgAttributes::new();
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adjust_for_rust_scalar(*cx, &mut attrs, scalar, *layout, offset, is_return);
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attrs
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});
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if arg.layout.is_zst() {
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// For some forsaken reason, x86_64-pc-windows-gnu
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// doesn't ignore zero-sized struct arguments.
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// The same is true for {s390x,sparc64,powerpc}-unknown-linux-{gnu,musl,uclibc}.
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if is_return
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|| rust_abi
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|| (!win_x64_gnu
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&& !linux_s390x_gnu_like
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&& !linux_sparc64_gnu_like
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&& !linux_powerpc_gnu_like)
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{
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arg.mode = PassMode::Ignore;
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}
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}
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Ok(arg)
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};
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let mut fn_abi = FnAbi {
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ret: arg_of(sig.output(), None)?,
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args: inputs
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.iter()
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.copied()
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.chain(extra_args.iter().copied())
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.chain(caller_location)
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.enumerate()
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.map(|(i, ty)| arg_of(ty, Some(i)))
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.collect::<Result<_, _>>()?,
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c_variadic: sig.c_variadic,
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fixed_count: inputs.len() as u32,
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conv,
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can_unwind: fn_can_unwind(cx.tcx(), fn_def_id, sig.abi),
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};
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fn_abi_adjust_for_abi(cx, &mut fn_abi, sig.abi, fn_def_id)?;
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debug!("fn_abi_new_uncached = {:?}", fn_abi);
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Ok(cx.tcx.arena.alloc(fn_abi))
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}
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#[tracing::instrument(level = "trace", skip(cx))]
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fn fn_abi_adjust_for_abi<'tcx>(
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cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
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fn_abi: &mut FnAbi<'tcx, Ty<'tcx>>,
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abi: SpecAbi,
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fn_def_id: Option<DefId>,
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) -> Result<(), FnAbiError<'tcx>> {
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if abi == SpecAbi::Unadjusted {
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return Ok(());
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}
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if abi == SpecAbi::Rust
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|| abi == SpecAbi::RustCall
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|| abi == SpecAbi::RustIntrinsic
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|| abi == SpecAbi::PlatformIntrinsic
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{
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// Look up the deduced parameter attributes for this function, if we have its def ID and
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// we're optimizing in non-incremental mode. We'll tag its parameters with those attributes
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// as appropriate.
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let deduced_param_attrs = if cx.tcx.sess.opts.optimize != OptLevel::No
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&& cx.tcx.sess.opts.incremental.is_none()
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{
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fn_def_id.map(|fn_def_id| cx.tcx.deduced_param_attrs(fn_def_id)).unwrap_or_default()
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} else {
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&[]
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};
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let fixup = |arg: &mut ArgAbi<'tcx, Ty<'tcx>>, arg_idx: Option<usize>| {
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if arg.is_ignore() {
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return;
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}
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match arg.layout.abi {
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Abi::Aggregate { .. } => {}
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// This is a fun case! The gist of what this is doing is
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// that we want callers and callees to always agree on the
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// ABI of how they pass SIMD arguments. If we were to *not*
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// make these arguments indirect then they'd be immediates
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// in LLVM, which means that they'd used whatever the
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// appropriate ABI is for the callee and the caller. That
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// means, for example, if the caller doesn't have AVX
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// enabled but the callee does, then passing an AVX argument
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// across this boundary would cause corrupt data to show up.
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//
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// This problem is fixed by unconditionally passing SIMD
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// arguments through memory between callers and callees
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// which should get them all to agree on ABI regardless of
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// target feature sets. Some more information about this
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// issue can be found in #44367.
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//
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// Note that the platform intrinsic ABI is exempt here as
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// that's how we connect up to LLVM and it's unstable
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// anyway, we control all calls to it in libstd.
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Abi::Vector { .. }
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if abi != SpecAbi::PlatformIntrinsic
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&& cx.tcx.sess.target.simd_types_indirect =>
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{
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arg.make_indirect();
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return;
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}
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_ => return,
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}
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let size = arg.layout.size;
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if arg.layout.is_unsized() || size > Pointer(AddressSpace::DATA).size(cx) {
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arg.make_indirect();
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} else {
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// We want to pass small aggregates as immediates, but using
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// a LLVM aggregate type for this leads to bad optimizations,
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// so we pick an appropriately sized integer type instead.
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arg.cast_to(Reg { kind: RegKind::Integer, size });
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}
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// If we deduced that this parameter was read-only, add that to the attribute list now.
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//
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// The `readonly` parameter only applies to pointers, so we can only do this if the
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// argument was passed indirectly. (If the argument is passed directly, it's an SSA
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// value, so it's implicitly immutable.)
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if let (Some(arg_idx), &mut PassMode::Indirect { ref mut attrs, .. }) =
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(arg_idx, &mut arg.mode)
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{
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// The `deduced_param_attrs` list could be empty if this is a type of function
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// we can't deduce any parameters for, so make sure the argument index is in
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// bounds.
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if let Some(deduced_param_attrs) = deduced_param_attrs.get(arg_idx) {
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if deduced_param_attrs.read_only {
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attrs.regular.insert(ArgAttribute::ReadOnly);
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debug!("added deduced read-only attribute");
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}
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}
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}
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};
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fixup(&mut fn_abi.ret, None);
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for (arg_idx, arg) in fn_abi.args.iter_mut().enumerate() {
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fixup(arg, Some(arg_idx));
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}
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} else {
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fn_abi.adjust_for_foreign_abi(cx, abi)?;
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}
|
|
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Ok(())
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}
|
|
|
|
#[tracing::instrument(level = "debug", skip(cx))]
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fn make_thin_self_ptr<'tcx>(
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cx: &(impl HasTyCtxt<'tcx> + HasParamEnv<'tcx>),
|
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layout: TyAndLayout<'tcx>,
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|
) -> TyAndLayout<'tcx> {
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|
let tcx = cx.tcx();
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let fat_pointer_ty = if layout.is_unsized() {
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// unsized `self` is passed as a pointer to `self`
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// FIXME (mikeyhew) change this to use &own if it is ever added to the language
|
|
tcx.mk_mut_ptr(layout.ty)
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} else {
|
|
match layout.abi {
|
|
Abi::ScalarPair(..) | Abi::Scalar(..) => (),
|
|
_ => bug!("receiver type has unsupported layout: {:?}", layout),
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|
}
|
|
|
|
// 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;
|
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'descend_newtypes: while !fat_pointer_layout.ty.is_unsafe_ptr()
|
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&& !fat_pointer_layout.ty.is_region_ptr()
|
|
{
|
|
for i in 0..fat_pointer_layout.fields.count() {
|
|
let field_layout = fat_pointer_layout.field(cx, i);
|
|
|
|
if !field_layout.is_zst() {
|
|
fat_pointer_layout = field_layout;
|
|
continue 'descend_newtypes;
|
|
}
|
|
}
|
|
|
|
bug!("receiver has no non-zero-sized fields {:?}", fat_pointer_layout);
|
|
}
|
|
|
|
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 = tcx.mk_mut_ptr(tcx.mk_unit());
|
|
|
|
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()
|
|
}
|
|
}
|