rust/compiler/rustc_passes/src/naked_functions.rs

305 lines
10 KiB
Rust

//! Checks validity of naked functions.
use rustc_ast::InlineAsmOptions;
use rustc_hir as hir;
use rustc_hir::def::DefKind;
use rustc_hir::def_id::{LocalDefId, LocalModDefId};
use rustc_hir::intravisit::Visitor;
use rustc_hir::{ExprKind, HirIdSet, InlineAsmOperand, StmtKind};
use rustc_middle::hir::nested_filter::OnlyBodies;
use rustc_middle::query::Providers;
use rustc_middle::ty::TyCtxt;
use rustc_session::lint::builtin::UNDEFINED_NAKED_FUNCTION_ABI;
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_target::spec::abi::Abi;
use crate::errors::{
NakedAsmOutsideNakedFn, NakedFunctionsAsmBlock, NakedFunctionsAsmOptions,
NakedFunctionsMustUseNoreturn, NakedFunctionsOperands, NoPatterns, ParamsNotAllowed,
UndefinedNakedFunctionAbi,
};
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { check_mod_naked_functions, ..*providers };
}
fn check_mod_naked_functions(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
let items = tcx.hir_module_items(module_def_id);
for def_id in items.definitions() {
if !matches!(tcx.def_kind(def_id), DefKind::Fn | DefKind::AssocFn) {
continue;
}
let (fn_header, body_id) = match tcx.hir_node_by_def_id(def_id) {
hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, _, body_id), .. })
| hir::Node::TraitItem(hir::TraitItem {
kind: hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)),
..
})
| hir::Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Fn(sig, body_id),
..
}) => (sig.header, *body_id),
_ => continue,
};
let body = tcx.hir().body(body_id);
if tcx.has_attr(def_id, sym::naked) {
check_abi(tcx, def_id, fn_header.abi);
check_no_patterns(tcx, body.params);
check_no_parameters_use(tcx, body);
check_asm(tcx, def_id, body);
} else {
// `naked_asm!` is not allowed outside of functions marked as `#[naked]`
let mut visitor = CheckNakedAsmInNakedFn { tcx };
visitor.visit_body(body);
}
}
}
/// Checks that function uses non-Rust ABI.
fn check_abi(tcx: TyCtxt<'_>, def_id: LocalDefId, abi: Abi) {
if abi == Abi::Rust {
let hir_id = tcx.local_def_id_to_hir_id(def_id);
let span = tcx.def_span(def_id);
tcx.emit_node_span_lint(
UNDEFINED_NAKED_FUNCTION_ABI,
hir_id,
span,
UndefinedNakedFunctionAbi,
);
}
}
/// Checks that parameters don't use patterns. Mirrors the checks for function declarations.
fn check_no_patterns(tcx: TyCtxt<'_>, params: &[hir::Param<'_>]) {
for param in params {
match param.pat.kind {
hir::PatKind::Wild | hir::PatKind::Binding(hir::BindingMode::NONE, _, _, None) => {}
_ => {
tcx.dcx().emit_err(NoPatterns { span: param.pat.span });
}
}
}
}
/// Checks that function parameters aren't used in the function body.
fn check_no_parameters_use<'tcx>(tcx: TyCtxt<'tcx>, body: &'tcx hir::Body<'tcx>) {
let mut params = HirIdSet::default();
for param in body.params {
param.pat.each_binding(|_binding_mode, hir_id, _span, _ident| {
params.insert(hir_id);
});
}
CheckParameters { tcx, params }.visit_body(body);
}
struct CheckParameters<'tcx> {
tcx: TyCtxt<'tcx>,
params: HirIdSet,
}
impl<'tcx> Visitor<'tcx> for CheckParameters<'tcx> {
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
if let hir::ExprKind::Path(hir::QPath::Resolved(
_,
hir::Path { res: hir::def::Res::Local(var_hir_id), .. },
)) = expr.kind
{
if self.params.contains(var_hir_id) {
self.tcx.dcx().emit_err(ParamsNotAllowed { span: expr.span });
return;
}
}
hir::intravisit::walk_expr(self, expr);
}
}
/// Checks that function body contains a single inline assembly block.
fn check_asm<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId, body: &'tcx hir::Body<'tcx>) {
let mut this = CheckInlineAssembly { tcx, items: Vec::new() };
this.visit_body(body);
if let [(ItemKind::Asm | ItemKind::Err, _)] = this.items[..] {
// Ok.
} else {
let mut must_show_error = false;
let mut has_asm = false;
let mut has_err = false;
let mut multiple_asms = vec![];
let mut non_asms = vec![];
for &(kind, span) in &this.items {
match kind {
ItemKind::Asm if has_asm => {
must_show_error = true;
multiple_asms.push(span);
}
ItemKind::Asm => has_asm = true,
ItemKind::NonAsm => {
must_show_error = true;
non_asms.push(span);
}
ItemKind::Err => has_err = true,
}
}
// If the naked function only contains a single asm block and a non-zero number of
// errors, then don't show an additional error. This allows for appending/prepending
// `compile_error!("...")` statements and reduces error noise.
if must_show_error || !has_err {
tcx.dcx().emit_err(NakedFunctionsAsmBlock {
span: tcx.def_span(def_id),
multiple_asms,
non_asms,
});
}
}
}
struct CheckInlineAssembly<'tcx> {
tcx: TyCtxt<'tcx>,
items: Vec<(ItemKind, Span)>,
}
#[derive(Copy, Clone)]
enum ItemKind {
Asm,
NonAsm,
Err,
}
impl<'tcx> CheckInlineAssembly<'tcx> {
fn check_expr(&mut self, expr: &'tcx hir::Expr<'tcx>, span: Span) {
match expr.kind {
ExprKind::ConstBlock(..)
| ExprKind::Array(..)
| ExprKind::Call(..)
| ExprKind::MethodCall(..)
| ExprKind::Tup(..)
| ExprKind::Binary(..)
| ExprKind::Unary(..)
| ExprKind::Lit(..)
| ExprKind::Cast(..)
| ExprKind::Type(..)
| ExprKind::Loop(..)
| ExprKind::Match(..)
| ExprKind::If(..)
| ExprKind::Closure { .. }
| ExprKind::Assign(..)
| ExprKind::AssignOp(..)
| ExprKind::Field(..)
| ExprKind::Index(..)
| ExprKind::Path(..)
| ExprKind::AddrOf(..)
| ExprKind::Let(..)
| ExprKind::Break(..)
| ExprKind::Continue(..)
| ExprKind::Ret(..)
| ExprKind::OffsetOf(..)
| ExprKind::Become(..)
| ExprKind::Struct(..)
| ExprKind::Repeat(..)
| ExprKind::Yield(..) => {
self.items.push((ItemKind::NonAsm, span));
}
ExprKind::InlineAsm(asm) => {
self.items.push((ItemKind::Asm, span));
self.check_inline_asm(asm, span);
}
ExprKind::DropTemps(..) | ExprKind::Block(..) => {
hir::intravisit::walk_expr(self, expr);
}
ExprKind::Err(_) => {
self.items.push((ItemKind::Err, span));
}
}
}
fn check_inline_asm(&self, asm: &'tcx hir::InlineAsm<'tcx>, span: Span) {
let unsupported_operands: Vec<Span> = asm
.operands
.iter()
.filter_map(|&(ref op, op_sp)| match op {
InlineAsmOperand::Const { .. }
| InlineAsmOperand::SymFn { .. }
| InlineAsmOperand::SymStatic { .. } => None,
InlineAsmOperand::In { .. }
| InlineAsmOperand::Out { .. }
| InlineAsmOperand::InOut { .. }
| InlineAsmOperand::SplitInOut { .. }
| InlineAsmOperand::Label { .. } => Some(op_sp),
})
.collect();
if !unsupported_operands.is_empty() {
self.tcx.dcx().emit_err(NakedFunctionsOperands { unsupported_operands });
}
let unsupported_options = asm.options.difference(InlineAsmOptions::NAKED_OPTIONS);
if !unsupported_options.is_empty() {
self.tcx.dcx().emit_err(NakedFunctionsAsmOptions {
span,
unsupported_options: unsupported_options
.human_readable_names()
.into_iter()
.map(|name| format!("`{name}`"))
.collect::<Vec<_>>()
.join(", "),
});
}
if !asm.options.contains(InlineAsmOptions::NORETURN) {
let last_span = asm
.operands
.last()
.map_or_else(|| asm.template_strs.last().unwrap().2, |op| op.1)
.shrink_to_hi();
self.tcx.dcx().emit_err(NakedFunctionsMustUseNoreturn { span, last_span });
}
}
}
impl<'tcx> Visitor<'tcx> for CheckInlineAssembly<'tcx> {
fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
match stmt.kind {
StmtKind::Item(..) => {}
StmtKind::Let(..) => {
self.items.push((ItemKind::NonAsm, stmt.span));
}
StmtKind::Expr(expr) | StmtKind::Semi(expr) => {
self.check_expr(expr, stmt.span);
}
}
}
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
self.check_expr(expr, expr.span);
}
}
struct CheckNakedAsmInNakedFn<'tcx> {
tcx: TyCtxt<'tcx>,
}
impl<'tcx> Visitor<'tcx> for CheckNakedAsmInNakedFn<'tcx> {
type NestedFilter = OnlyBodies;
fn nested_visit_map(&mut self) -> Self::Map {
self.tcx.hir()
}
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
if let ExprKind::InlineAsm(inline_asm) = expr.kind {
if let rustc_ast::AsmMacro::NakedAsm = inline_asm.asm_macro {
self.tcx.dcx().emit_err(NakedAsmOutsideNakedFn { span: expr.span });
}
}
hir::intravisit::walk_expr(self, expr);
}
}