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use rustc_ast::{ast, attr, MetaItemKind, NestedMetaItem};
use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::codes::*;
use rustc_errors::{struct_span_code_err, DiagMessage, SubdiagMessage};
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
use rustc_hir::{lang_items, LangItem};
use rustc_middle::middle::codegen_fn_attrs::{
CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry, TargetFeature,
};
use rustc_middle::mir::mono::Linkage;
use rustc_middle::query::Providers;
use rustc_middle::ty::{self as ty, TyCtxt};
use rustc_session::lint;
use rustc_session::parse::feature_err;
use rustc_span::symbol::Ident;
use rustc_span::{sym, Span};
use rustc_target::abi::VariantIdx;
use rustc_target::spec::{abi, SanitizerSet};
use crate::errors;
use crate::target_features::{check_target_feature_trait_unsafe, from_target_feature};
fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
use rustc_middle::mir::mono::Linkage::*;
// Use the names from src/llvm/docs/LangRef.rst here. Most types are only
// applicable to variable declarations and may not really make sense for
// Rust code in the first place but allow them anyway and trust that the
// user knows what they're doing. Who knows, unanticipated use cases may pop
// up in the future.
//
// ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
// and don't have to be, LLVM treats them as no-ops.
match name {
"appending" => Appending,
"available_externally" => AvailableExternally,
"common" => Common,
"extern_weak" => ExternalWeak,
"external" => External,
"internal" => Internal,
"linkonce" => LinkOnceAny,
"linkonce_odr" => LinkOnceODR,
"private" => Private,
"weak" => WeakAny,
"weak_odr" => WeakODR,
_ => tcx.dcx().span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
}
}
fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
if cfg!(debug_assertions) {
let def_kind = tcx.def_kind(did);
assert!(
def_kind.has_codegen_attrs(),
"unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
);
}
let attrs = tcx.hir().attrs(tcx.local_def_id_to_hir_id(did));
let mut codegen_fn_attrs = CodegenFnAttrs::new();
if tcx.should_inherit_track_caller(did) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
}
// When `no_builtins` is applied at the crate level, we should add the
// `no-builtins` attribute to each function to ensure it takes effect in LTO.
let crate_attrs = tcx.hir().attrs(rustc_hir::CRATE_HIR_ID);
let no_builtins = attr::contains_name(crate_attrs, sym::no_builtins);
if no_builtins {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_BUILTINS;
}
let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
let mut inline_span = None;
let mut link_ordinal_span = None;
let mut no_sanitize_span = None;
let fn_sig_outer = || {
use DefKind::*;
let def_kind = tcx.def_kind(did);
if let Fn | AssocFn | Variant | Ctor(..) = def_kind { Some(tcx.fn_sig(did)) } else { None }
};
for attr in attrs.iter() {
// In some cases, attribute are only valid on functions, but it's the `check_attr`
// pass that check that they aren't used anywhere else, rather this module.
// In these cases, we bail from performing further checks that are only meaningful for
// functions (such as calling `fn_sig`, which ICEs if given a non-function). We also
// report a delayed bug, just in case `check_attr` isn't doing its job.
let fn_sig = || {
let sig = fn_sig_outer();
if sig.is_none() {
tcx.dcx()
.span_delayed_bug(attr.span, "this attribute can only be applied to functions");
}
sig
};
let Some(Ident { name, .. }) = attr.ident() else {
continue;
};
match name {
sym::cold => codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD,
sym::rustc_allocator => codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR,
sym::ffi_pure => codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE,
sym::ffi_const => codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST,
sym::rustc_nounwind => codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND,
sym::rustc_reallocator => codegen_fn_attrs.flags |= CodegenFnAttrFlags::REALLOCATOR,
sym::rustc_deallocator => codegen_fn_attrs.flags |= CodegenFnAttrFlags::DEALLOCATOR,
sym::rustc_allocator_zeroed => {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED
}
sym::naked => codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED,
sym::no_mangle => {
if tcx.opt_item_name(did.to_def_id()).is_some() {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE
} else {
tcx.dcx()
.struct_span_err(
attr.span,
format!(
"`#[no_mangle]` cannot be used on {} {} as it has no name",
tcx.def_descr_article(did.to_def_id()),
tcx.def_descr(did.to_def_id()),
),
)
.emit();
}
}
sym::rustc_std_internal_symbol => {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL
}
sym::used => {
let inner = attr.meta_item_list();
match inner.as_deref() {
Some([item]) if item.has_name(sym::linker) => {
if !tcx.features().used_with_arg {
feature_err(
&tcx.sess,
sym::used_with_arg,
attr.span,
"`#[used(linker)]` is currently unstable",
)
.emit();
}
codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
}
Some([item]) if item.has_name(sym::compiler) => {
if !tcx.features().used_with_arg {
feature_err(
&tcx.sess,
sym::used_with_arg,
attr.span,
"`#[used(compiler)]` is currently unstable",
)
.emit();
}
codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
}
Some(_) => {
tcx.dcx().emit_err(errors::ExpectedUsedSymbol { span: attr.span });
}
None => {
// Unfortunately, unconditionally using `llvm.used` causes
// issues in handling `.init_array` with the gold linker,
// but using `llvm.compiler.used` caused a nontrivial amount
// of unintentional ecosystem breakage -- particularly on
// Mach-O targets.
//
// As a result, we emit `llvm.compiler.used` only on ELF
// targets. This is somewhat ad-hoc, but actually follows
// our pre-LLVM 13 behavior (prior to the ecosystem
// breakage), and seems to match `clang`'s behavior as well
// (both before and after LLVM 13), possibly because they
// have similar compatibility concerns to us. See
// https://github.com/rust-lang/rust/issues/47384#issuecomment-1019080146
// and following comments for some discussion of this, as
// well as the comments in `rustc_codegen_llvm` where these
// flags are handled.
//
// Anyway, to be clear: this is still up in the air
// somewhat, and is subject to change in the future (which
// is a good thing, because this would ideally be a bit
// more firmed up).
let is_like_elf = !(tcx.sess.target.is_like_osx
|| tcx.sess.target.is_like_windows
|| tcx.sess.target.is_like_wasm);
codegen_fn_attrs.flags |= if is_like_elf {
CodegenFnAttrFlags::USED
} else {
CodegenFnAttrFlags::USED_LINKER
};
}
}
}
sym::cmse_nonsecure_entry => {
if let Some(fn_sig) = fn_sig()
&& !matches!(fn_sig.skip_binder().abi(), abi::Abi::C { .. })
{
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0776,
"`#[cmse_nonsecure_entry]` requires C ABI"
)
.emit();
}
if !tcx.sess.target.llvm_target.contains("thumbv8m") {
struct_span_code_err!(tcx.dcx(), attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
.emit();
}
codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY
}
sym::thread_local => codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL,
sym::track_caller => {
let is_closure = tcx.is_closure_like(did.to_def_id());
if !is_closure
&& let Some(fn_sig) = fn_sig()
&& fn_sig.skip_binder().abi() != abi::Abi::Rust
{
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0737,
"`#[track_caller]` requires Rust ABI"
)
.emit();
}
if is_closure
&& !tcx.features().closure_track_caller
&& !attr.span.allows_unstable(sym::closure_track_caller)
{
feature_err(
&tcx.sess,
sym::closure_track_caller,
attr.span,
"`#[track_caller]` on closures is currently unstable",
)
.emit();
}
codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER
}
sym::export_name => {
if let Some(s) = attr.value_str() {
if s.as_str().contains('\0') {
// `#[export_name = ...]` will be converted to a null-terminated string,
// so it may not contain any null characters.
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0648,
"`export_name` may not contain null characters"
)
.emit();
}
codegen_fn_attrs.export_name = Some(s);
}
}
sym::target_feature => {
if !tcx.is_closure_like(did.to_def_id())
&& let Some(fn_sig) = fn_sig()
&& fn_sig.skip_binder().safety() == hir::Safety::Safe
{
if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
// The `#[target_feature]` attribute is allowed on
// WebAssembly targets on all functions, including safe
// ones. Other targets require that `#[target_feature]` is
// only applied to unsafe functions (pending the
// `target_feature_11` feature) because on most targets
// execution of instructions that are not supported is
// considered undefined behavior. For WebAssembly which is a
// 100% safe target at execution time it's not possible to
// execute undefined instructions, and even if a future
// feature was added in some form for this it would be a
// deterministic trap. There is no undefined behavior when
// executing WebAssembly so `#[target_feature]` is allowed
// on safe functions (but again, only for WebAssembly)
//
// Note that this is also allowed if `actually_rustdoc` so
// if a target is documenting some wasm-specific code then
// it's not spuriously denied.
//
// This exception needs to be kept in sync with allowing
// `#[target_feature]` on `main` and `start`.
} else if !tcx.features().target_feature_11 {
feature_err(
&tcx.sess,
sym::target_feature_11,
attr.span,
"`#[target_feature(..)]` can only be applied to `unsafe` functions",
)
.with_span_label(tcx.def_span(did), "not an `unsafe` function")
.emit();
} else {
check_target_feature_trait_unsafe(tcx, did, attr.span);
}
}
from_target_feature(
tcx,
attr,
supported_target_features,
&mut codegen_fn_attrs.target_features,
);
}
sym::linkage => {
if let Some(val) = attr.value_str() {
let linkage = Some(linkage_by_name(tcx, did, val.as_str()));
if tcx.is_foreign_item(did) {
codegen_fn_attrs.import_linkage = linkage;
if tcx.is_mutable_static(did.into()) {
let mut diag = tcx.dcx().struct_span_err(
attr.span,
"extern mutable statics are not allowed with `#[linkage]`",
);
diag.note(
"marking the extern static mutable would allow changing which symbol \
the static references rather than make the target of the symbol \
mutable",
);
diag.emit();
}
} else {
codegen_fn_attrs.linkage = linkage;
}
}
}
sym::link_section => {
if let Some(val) = attr.value_str() {
if val.as_str().bytes().any(|b| b == 0) {
let msg = format!("illegal null byte in link_section value: `{val}`");
tcx.dcx().span_err(attr.span, msg);
} else {
codegen_fn_attrs.link_section = Some(val);
}
}
}
sym::link_name => codegen_fn_attrs.link_name = attr.value_str(),
sym::link_ordinal => {
link_ordinal_span = Some(attr.span);
if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
codegen_fn_attrs.link_ordinal = ordinal;
}
}
sym::no_sanitize => {
no_sanitize_span = Some(attr.span);
if let Some(list) = attr.meta_item_list() {
for item in list.iter() {
match item.name_or_empty() {
sym::address => {
codegen_fn_attrs.no_sanitize |=
SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS
}
sym::cfi => codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI,
sym::kcfi => codegen_fn_attrs.no_sanitize |= SanitizerSet::KCFI,
sym::memory => codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY,
sym::memtag => codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG,
sym::shadow_call_stack => {
codegen_fn_attrs.no_sanitize |= SanitizerSet::SHADOWCALLSTACK
}
sym::thread => codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD,
sym::hwaddress => {
codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS
}
_ => {
tcx.dcx().emit_err(errors::InvalidNoSanitize { span: item.span() });
}
}
}
}
}
sym::instruction_set => {
codegen_fn_attrs.instruction_set =
attr.meta_item_list().and_then(|l| match &l[..] {
[NestedMetaItem::MetaItem(set)] => {
let segments =
set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
match segments.as_slice() {
[sym::arm, sym::a32] | [sym::arm, sym::t32] => {
if !tcx.sess.target.has_thumb_interworking {
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0779,
"target does not support `#[instruction_set]`"
)
.emit();
None
} else if segments[1] == sym::a32 {
Some(InstructionSetAttr::ArmA32)
} else if segments[1] == sym::t32 {
Some(InstructionSetAttr::ArmT32)
} else {
unreachable!()
}
}
_ => {
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0779,
"invalid instruction set specified",
)
.emit();
None
}
}
}
[] => {
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0778,
"`#[instruction_set]` requires an argument"
)
.emit();
None
}
_ => {
struct_span_code_err!(
tcx.dcx(),
attr.span,
E0779,
"cannot specify more than one instruction set"
)
.emit();
None
}
})
}
sym::repr => {
codegen_fn_attrs.alignment = if let Some(items) = attr.meta_item_list()
&& let [item] = items.as_slice()
&& let Some((sym::align, literal)) = item.singleton_lit_list()
{
rustc_attr::parse_alignment(&literal.kind)
.map_err(|msg| {
struct_span_code_err!(
tcx.dcx(),
literal.span,
E0589,
"invalid `repr(align)` attribute: {}",
msg
)
.emit();
})
.ok()
} else {
None
};
}
sym::patchable_function_entry => {
codegen_fn_attrs.patchable_function_entry = attr.meta_item_list().and_then(|l| {
let mut prefix = None;
let mut entry = None;
for item in l {
let Some(meta_item) = item.meta_item() else {
tcx.dcx().span_err(item.span(), "expected name value pair");
continue;
};
let Some(name_value_lit) = meta_item.name_value_literal() else {
tcx.dcx().span_err(item.span(), "expected name value pair");
continue;
};
fn emit_error_with_label(
tcx: TyCtxt<'_>,
span: Span,
error: impl Into<DiagMessage>,
label: impl Into<SubdiagMessage>,
) {
let mut err: rustc_errors::Diag<'_, _> =
tcx.dcx().struct_span_err(span, error);
err.span_label(span, label);
err.emit();
}
let attrib_to_write = match meta_item.name_or_empty() {
sym::prefix_nops => &mut prefix,
sym::entry_nops => &mut entry,
_ => {
emit_error_with_label(
tcx,
item.span(),
"unexpected parameter name",
format!("expected {} or {}", sym::prefix_nops, sym::entry_nops),
);
continue;
}
};
let rustc_ast::LitKind::Int(val, _) = name_value_lit.kind else {
emit_error_with_label(
tcx,
name_value_lit.span,
"invalid literal value",
"value must be an integer between `0` and `255`",
);
continue;
};
let Ok(val) = val.get().try_into() else {
emit_error_with_label(
tcx,
name_value_lit.span,
"integer value out of range",
"value must be between `0` and `255`",
);
continue;
};
*attrib_to_write = Some(val);
}
if let (None, None) = (prefix, entry) {
tcx.dcx().span_err(attr.span, "must specify at least one parameter");
}
Some(PatchableFunctionEntry::from_prefix_and_entry(
prefix.unwrap_or(0),
entry.unwrap_or(0),
))
})
}
_ => {}
}
}
codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
if !attr.has_name(sym::inline) {
return ia;
}
match attr.meta_kind() {
Some(MetaItemKind::Word) => InlineAttr::Hint,
Some(MetaItemKind::List(ref items)) => {
inline_span = Some(attr.span);
if items.len() != 1 {
struct_span_code_err!(tcx.dcx(), attr.span, E0534, "expected one argument")
.emit();
InlineAttr::None
} else if list_contains_name(items, sym::always) {
InlineAttr::Always
} else if list_contains_name(items, sym::never) {
InlineAttr::Never
} else {
struct_span_code_err!(tcx.dcx(), items[0].span(), E0535, "invalid argument")
.with_help("valid inline arguments are `always` and `never`")
.emit();
InlineAttr::None
}
}
Some(MetaItemKind::NameValue(_)) => ia,
None => ia,
}
});
codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
if !attr.has_name(sym::optimize) {
return ia;
}
let err = |sp, s| struct_span_code_err!(tcx.dcx(), sp, E0722, "{}", s).emit();
match attr.meta_kind() {
Some(MetaItemKind::Word) => {
err(attr.span, "expected one argument");
ia
}
Some(MetaItemKind::List(ref items)) => {
inline_span = Some(attr.span);
if items.len() != 1 {
err(attr.span, "expected one argument");
OptimizeAttr::None
} else if list_contains_name(items, sym::size) {
OptimizeAttr::Size
} else if list_contains_name(items, sym::speed) {
OptimizeAttr::Speed
} else {
err(items[0].span(), "invalid argument");
OptimizeAttr::None
}
}
Some(MetaItemKind::NameValue(_)) => ia,
None => ia,
}
});
// #73631: closures inherit `#[target_feature]` annotations
//
// If this closure is marked `#[inline(always)]`, simply skip adding `#[target_feature]`.
//
// At this point, `unsafe` has already been checked and `#[target_feature]` only affects codegen.
// Emitting both `#[inline(always)]` and `#[target_feature]` can potentially result in an
// ICE, because LLVM errors when the function fails to be inlined due to a target feature
// mismatch.
//
// Using `#[inline(always)]` implies that this closure will most likely be inlined into
// its parent function, which effectively inherits the features anyway. Boxing this closure
// would result in this closure being compiled without the inherited target features, but this
// is probably a poor usage of `#[inline(always)]` and easily avoided by not using the attribute.
if tcx.features().target_feature_11
&& tcx.is_closure_like(did.to_def_id())
&& codegen_fn_attrs.inline != InlineAttr::Always
{
let owner_id = tcx.parent(did.to_def_id());
if tcx.def_kind(owner_id).has_codegen_attrs() {
codegen_fn_attrs
.target_features
.extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied());
}
}
if let Some(sig) = fn_sig_outer() {
// Collect target features from types reachable from arguments.
// We define a type as "reachable" if:
// - it is a function argument
// - it is a field of a reachable struct
// - there is a reachable reference to it
// FIXME(struct_target_features): we may want to cache the result of this computation.
let mut visited_types = FxHashSet::default();
let mut reachable_types: Vec<_> = sig.skip_binder().inputs().skip_binder().to_owned();
let mut additional_tf = vec![];
while let Some(ty) = reachable_types.pop() {
if visited_types.contains(&ty) {
continue;
}
visited_types.insert(ty);
match ty.kind() {
ty::Alias(..) => {
if let Ok(t) =
tcx.try_normalize_erasing_regions(tcx.param_env(did.to_def_id()), ty)
{
reachable_types.push(t)
}
}
ty::Ref(_, inner, _) => reachable_types.push(*inner),
ty::Tuple(tys) => reachable_types.extend(tys.iter()),
ty::Adt(adt_def, args) => {
additional_tf.extend_from_slice(tcx.struct_target_features(adt_def.did()));
// This only recurses into structs as i.e. an Option<TargetFeature> is an ADT
// that doesn't actually always contain a TargetFeature.
if adt_def.is_struct() {
reachable_types.extend(
adt_def
.variant(VariantIdx::from_usize(0))
.fields
.iter()
.map(|field| field.ty(tcx, args)),
);
}
}
ty::Bool
| ty::Char
| ty::Int(..)
| ty::Uint(..)
| ty::Float(..)
| ty::Foreign(..)
| ty::Str
| ty::Array(..)
| ty::Pat(..)
| ty::Slice(..)
| ty::RawPtr(..)
| ty::FnDef(..)
| ty::FnPtr(..)
| ty::Dynamic(..)
| ty::Closure(..)
| ty::CoroutineClosure(..)
| ty::Coroutine(..)
| ty::CoroutineWitness(..)
| ty::Never
| ty::Param(..)
| ty::Bound(..)
| ty::Placeholder(..)
| ty::Infer(..)
| ty::Error(..) => (),
}
}
// FIXME(struct_target_features): is this really necessary?
if !additional_tf.is_empty() && sig.skip_binder().abi() != abi::Abi::Rust {
tcx.dcx().span_err(
tcx.hir().span(tcx.local_def_id_to_hir_id(did)),
"cannot use a struct with target features in a function with non-Rust ABI",
);
}
if !additional_tf.is_empty() && codegen_fn_attrs.inline == InlineAttr::Always {
tcx.dcx().span_err(
tcx.hir().span(tcx.local_def_id_to_hir_id(did)),
"cannot use a struct with target features in a #[inline(always)] function",
);
}
codegen_fn_attrs
.target_features
.extend(additional_tf.iter().map(|tf| TargetFeature { implied: true, ..*tf }));
}
// If a function uses non-default target_features it can't be inlined into general
// purpose functions as they wouldn't have the right target features
// enabled. For that reason we also forbid #[inline(always)] as it can't be
// respected.
if !codegen_fn_attrs.target_features.is_empty() {
if codegen_fn_attrs.inline == InlineAttr::Always {
if let Some(span) = inline_span {
tcx.dcx().span_err(
span,
"cannot use `#[inline(always)]` with \
`#[target_feature]`",
);
}
}
}
if !codegen_fn_attrs.no_sanitize.is_empty() {
if codegen_fn_attrs.inline == InlineAttr::Always {
if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
let hir_id = tcx.local_def_id_to_hir_id(did);
tcx.node_span_lint(
lint::builtin::INLINE_NO_SANITIZE,
hir_id,
no_sanitize_span,
|lint| {
lint.primary_message("`no_sanitize` will have no effect after inlining");
lint.span_note(inline_span, "inlining requested here");
},
)
}
}
}
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {
codegen_fn_attrs.inline = InlineAttr::Never;
}
// Weak lang items have the same semantics as "std internal" symbols in the
// sense that they're preserved through all our LTO passes and only
// strippable by the linker.
//
// Additionally weak lang items have predetermined symbol names.
if WEAK_LANG_ITEMS.iter().any(|&l| tcx.lang_items().get(l) == Some(did.to_def_id())) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
}
if let Some((name, _)) = lang_items::extract(attrs)
&& let Some(lang_item) = LangItem::from_name(name)
&& let Some(link_name) = lang_item.link_name()
{
codegen_fn_attrs.export_name = Some(link_name);
codegen_fn_attrs.link_name = Some(link_name);
}
check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
// Internal symbols to the standard library all have no_mangle semantics in
// that they have defined symbol names present in the function name. This
// also applies to weak symbols where they all have known symbol names.
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
}
// Any linkage to LLVM intrinsics for now forcibly marks them all as never
// unwinds since LLVM sometimes can't handle codegen which `invoke`s
// intrinsic functions.
if let Some(name) = &codegen_fn_attrs.link_name {
if name.as_str().starts_with("llvm.") {
codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
}
}
codegen_fn_attrs
}
/// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
/// applied to the method prototype.
fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
if let Some(impl_item) = tcx.opt_associated_item(def_id)
&& let ty::AssocItemContainer::ImplContainer = impl_item.container
&& let Some(trait_item) = impl_item.trait_item_def_id
{
return tcx.codegen_fn_attrs(trait_item).flags.intersects(CodegenFnAttrFlags::TRACK_CALLER);
}
false
}
fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
use rustc_ast::{LitIntType, LitKind, MetaItemLit};
let meta_item_list = attr.meta_item_list();
let meta_item_list = meta_item_list.as_deref();
let sole_meta_list = match meta_item_list {
Some([item]) => item.lit(),
Some(_) => {
tcx.dcx().emit_err(errors::InvalidLinkOrdinalNargs { span: attr.span });
return None;
}
_ => None,
};
if let Some(MetaItemLit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) =
sole_meta_list
{
// According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
// the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
// in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
// to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
//
// FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
// both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
// a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
// for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
// library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
// if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
// about LINK.EXE failing.)
if *ordinal <= u16::MAX as u128 {
Some(ordinal.get() as u16)
} else {
let msg = format!("ordinal value in `link_ordinal` is too large: `{ordinal}`");
tcx.dcx()
.struct_span_err(attr.span, msg)
.with_note("the value may not exceed `u16::MAX`")
.emit();
None
}
} else {
tcx.dcx().emit_err(errors::InvalidLinkOrdinalFormat { span: attr.span });
None
}
}
fn check_link_name_xor_ordinal(
tcx: TyCtxt<'_>,
codegen_fn_attrs: &CodegenFnAttrs,
inline_span: Option<Span>,
) {
if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
return;
}
let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
if let Some(span) = inline_span {
tcx.dcx().span_err(span, msg);
} else {
tcx.dcx().err(msg);
}
}
fn struct_target_features(tcx: TyCtxt<'_>, def_id: LocalDefId) -> &[TargetFeature] {
let mut features = vec![];
let supported_features = tcx.supported_target_features(LOCAL_CRATE);
for attr in tcx.get_attrs(def_id, sym::target_feature) {
from_target_feature(tcx, attr, supported_features, &mut features);
}
tcx.arena.alloc_slice(&features)
}
pub fn provide(providers: &mut Providers) {
*providers = Providers {
codegen_fn_attrs,
should_inherit_track_caller,
struct_target_features,
..*providers
};
}