1 use rustc_ast::InlineAsmTemplatePiece;
2 use rustc_data_structures::stable_set::FxHashSet;
3 use rustc_errors::struct_span_err;
5 use rustc_index::vec::Idx;
6 use rustc_middle::ty::layout::{LayoutError, SizeSkeleton};
7 use rustc_middle::ty::{self, FloatTy, InferTy, IntTy, Ty, TyCtxt, TypeFoldable, UintTy};
8 use rustc_session::lint;
9 use rustc_span::{Span, Symbol, DUMMY_SP};
10 use rustc_target::abi::{Pointer, VariantIdx};
11 use rustc_target::asm::{InlineAsmReg, InlineAsmRegClass, InlineAsmRegOrRegClass, InlineAsmType};
15 /// If the type is `Option<T>`, it will return `T`, otherwise
16 /// the type itself. Works on most `Option`-like types.
17 fn unpack_option_like<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
18 let ty::Adt(def, substs) = *ty.kind() else { return ty };
20 if def.variants().len() == 2 && !def.repr().c() && def.repr().int.is_none() {
23 let one = VariantIdx::new(1);
24 let zero = VariantIdx::new(0);
26 if def.variant(zero).fields.is_empty() {
28 } else if def.variant(one).fields.is_empty() {
34 if def.variant(data_idx).fields.len() == 1 {
35 return def.variant(data_idx).fields[0].ty(tcx, substs);
42 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
43 pub fn check_transmute(&self, span: Span, from: Ty<'tcx>, to: Ty<'tcx>) {
44 let convert = |ty: Ty<'tcx>| {
45 let ty = self.resolve_vars_if_possible(ty);
46 let ty = self.tcx.normalize_erasing_regions(self.param_env, ty);
47 (SizeSkeleton::compute(ty, self.tcx, self.param_env), ty)
49 let (sk_from, from) = convert(from);
50 let (sk_to, to) = convert(to);
52 // Check for same size using the skeletons.
53 if let (Ok(sk_from), Ok(sk_to)) = (sk_from, sk_to) {
54 if sk_from.same_size(sk_to) {
58 // Special-case transmuting from `typeof(function)` and
59 // `Option<typeof(function)>` to present a clearer error.
60 let from = unpack_option_like(self.tcx, from);
61 if let (&ty::FnDef(..), SizeSkeleton::Known(size_to)) = (from.kind(), sk_to) && size_to == Pointer.size(&self.tcx) {
62 struct_span_err!(self.tcx.sess, span, E0591, "can't transmute zero-sized type")
63 .note(&format!("source type: {from}"))
64 .note(&format!("target type: {to}"))
65 .help("cast with `as` to a pointer instead")
71 // Try to display a sensible error with as much information as possible.
72 let skeleton_string = |ty: Ty<'tcx>, sk| match sk {
73 Ok(SizeSkeleton::Known(size)) => format!("{} bits", size.bits()),
74 Ok(SizeSkeleton::Pointer { tail, .. }) => format!("pointer to `{tail}`"),
75 Err(LayoutError::Unknown(bad)) => {
77 "this type does not have a fixed size".to_owned()
79 format!("size can vary because of {bad}")
82 Err(err) => err.to_string(),
85 let mut err = struct_span_err!(
89 "cannot transmute between types of different sizes, \
90 or dependently-sized types"
93 err.note(&format!("`{from}` does not have a fixed size"));
95 err.note(&format!("source type: `{}` ({})", from, skeleton_string(from, sk_from)))
96 .note(&format!("target type: `{}` ({})", to, skeleton_string(to, sk_to)));
101 fn is_thin_ptr_ty(&self, ty: Ty<'tcx>) -> bool {
102 if ty.is_sized(self.tcx.at(DUMMY_SP), self.param_env) {
105 if let ty::Foreign(..) = ty.kind() {
111 fn check_asm_operand_type(
114 reg: InlineAsmRegOrRegClass,
115 expr: &hir::Expr<'tcx>,
116 template: &[InlineAsmTemplatePiece],
118 tied_input: Option<(&hir::Expr<'tcx>, Option<InlineAsmType>)>,
119 target_features: &FxHashSet<Symbol>,
120 ) -> Option<InlineAsmType> {
121 // Check the type against the allowed types for inline asm.
122 let ty = self.typeck_results.borrow().expr_ty_adjusted(expr);
123 let ty = self.resolve_vars_if_possible(ty);
124 let asm_ty_isize = match self.tcx.sess.target.pointer_width {
125 16 => InlineAsmType::I16,
126 32 => InlineAsmType::I32,
127 64 => InlineAsmType::I64,
130 let asm_ty = match *ty.kind() {
131 // `!` is allowed for input but not for output (issue #87802)
132 ty::Never if is_input => return None,
133 ty::Error(_) => return None,
134 ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Some(InlineAsmType::I8),
135 ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => Some(InlineAsmType::I16),
136 // Somewhat of a hack: fallback in the presence of errors does not actually
137 // fall back to i32, but to ty::Error. For integer inference variables this
138 // means that they don't get any fallback and stay as `{integer}`.
139 // Since compilation can't succeed anyway, it's fine to use this to avoid printing
140 // "cannot use value of type `{integer}`", even though that would absolutely
141 // work due due i32 fallback if the current function had no other errors.
142 ty::Infer(InferTy::IntVar(_)) => {
143 assert!(self.is_tainted_by_errors());
144 Some(InlineAsmType::I32)
146 ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => Some(InlineAsmType::I32),
147 ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => Some(InlineAsmType::I64),
148 ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => Some(InlineAsmType::I128),
149 ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(asm_ty_isize),
150 ty::Infer(InferTy::FloatVar(_)) => {
151 assert!(self.is_tainted_by_errors());
152 Some(InlineAsmType::F32)
154 ty::Float(FloatTy::F32) => Some(InlineAsmType::F32),
155 ty::Float(FloatTy::F64) => Some(InlineAsmType::F64),
156 ty::FnPtr(_) => Some(asm_ty_isize),
157 ty::RawPtr(ty::TypeAndMut { ty, mutbl: _ }) if self.is_thin_ptr_ty(ty) => {
160 ty::Adt(adt, substs) if adt.repr().simd() => {
161 let fields = &adt.non_enum_variant().fields;
162 let elem_ty = fields[0].ty(self.tcx, substs);
163 match elem_ty.kind() {
164 ty::Never | ty::Error(_) => return None,
165 ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => {
166 Some(InlineAsmType::VecI8(fields.len() as u64))
168 ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => {
169 Some(InlineAsmType::VecI16(fields.len() as u64))
171 ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => {
172 Some(InlineAsmType::VecI32(fields.len() as u64))
174 ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => {
175 Some(InlineAsmType::VecI64(fields.len() as u64))
177 ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => {
178 Some(InlineAsmType::VecI128(fields.len() as u64))
180 ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => {
181 Some(match self.tcx.sess.target.pointer_width {
182 16 => InlineAsmType::VecI16(fields.len() as u64),
183 32 => InlineAsmType::VecI32(fields.len() as u64),
184 64 => InlineAsmType::VecI64(fields.len() as u64),
188 ty::Float(FloatTy::F32) => Some(InlineAsmType::VecF32(fields.len() as u64)),
189 ty::Float(FloatTy::F64) => Some(InlineAsmType::VecF64(fields.len() as u64)),
195 let Some(asm_ty) = asm_ty else {
196 let msg = &format!("cannot use value of type `{ty}` for inline assembly");
197 let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
199 "only integers, floats, SIMD vectors, pointers and function pointers \
200 can be used as arguments for inline assembly",
206 if ty.has_infer_types_or_consts() {
207 assert!(self.is_tainted_by_errors());
211 // Check that the type implements Copy. The only case where this can
212 // possibly fail is for SIMD types which don't #[derive(Copy)].
213 if !ty.is_copy_modulo_regions(self.tcx.at(DUMMY_SP), self.param_env) {
214 let msg = "arguments for inline assembly must be copyable";
215 let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
216 err.note(&format!("`{ty}` does not implement the Copy trait"));
220 // Ideally we wouldn't need to do this, but LLVM's register allocator
221 // really doesn't like it when tied operands have different types.
223 // This is purely an LLVM limitation, but we have to live with it since
224 // there is no way to hide this with implicit conversions.
226 // For the purposes of this check we only look at the `InlineAsmType`,
227 // which means that pointers and integers are treated as identical (modulo
229 if let Some((in_expr, Some(in_asm_ty))) = tied_input {
230 if in_asm_ty != asm_ty {
231 let msg = "incompatible types for asm inout argument";
232 let mut err = self.tcx.sess.struct_span_err(vec![in_expr.span, expr.span], msg);
234 let in_expr_ty = self.typeck_results.borrow().expr_ty_adjusted(in_expr);
235 let in_expr_ty = self.resolve_vars_if_possible(in_expr_ty);
236 err.span_label(in_expr.span, &format!("type `{in_expr_ty}`"));
237 err.span_label(expr.span, &format!("type `{ty}`"));
239 "asm inout arguments must have the same type, \
240 unless they are both pointers or integers of the same size",
245 // All of the later checks have already been done on the input, so
246 // let's not emit errors and warnings twice.
250 // Check the type against the list of types supported by the selected
252 let asm_arch = self.tcx.sess.asm_arch.unwrap();
253 let reg_class = reg.reg_class();
254 let supported_tys = reg_class.supported_types(asm_arch);
255 let Some((_, feature)) = supported_tys.iter().find(|&&(t, _)| t == asm_ty) else {
256 let msg = &format!("type `{ty}` cannot be used with this register class");
257 let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
258 let supported_tys: Vec<_> =
259 supported_tys.iter().map(|(t, _)| t.to_string()).collect();
261 "register class `{}` supports these types: {}",
263 supported_tys.join(", "),
265 if let Some(suggest) = reg_class.suggest_class(asm_arch, asm_ty) {
267 "consider using the `{}` register class instead",
275 // Check whether the selected type requires a target feature. Note that
276 // this is different from the feature check we did earlier. While the
277 // previous check checked that this register class is usable at all
278 // with the currently enabled features, some types may only be usable
279 // with a register class when a certain feature is enabled. We check
280 // this here since it depends on the results of typeck.
282 // Also note that this check isn't run when the operand type is never
283 // (!). In that case we still need the earlier check to verify that the
284 // register class is usable at all.
285 if let Some(feature) = feature {
286 if !target_features.contains(&feature) {
287 let msg = &format!("`{}` target feature is not enabled", feature);
288 let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
290 "this is required to use type `{}` with register class `{}`",
299 // Check whether a modifier is suggested for using this type.
300 if let Some((suggested_modifier, suggested_result)) =
301 reg_class.suggest_modifier(asm_arch, asm_ty)
303 // Search for any use of this operand without a modifier and emit
304 // the suggestion for them.
305 let mut spans = vec![];
306 for piece in template {
307 if let &InlineAsmTemplatePiece::Placeholder { operand_idx, modifier, span } = piece
309 if operand_idx == idx && modifier.is_none() {
314 if !spans.is_empty() {
315 let (default_modifier, default_result) =
316 reg_class.default_modifier(asm_arch).unwrap();
317 self.tcx.struct_span_lint_hir(
318 lint::builtin::ASM_SUB_REGISTER,
322 let msg = "formatting may not be suitable for sub-register argument";
323 let mut err = lint.build(msg);
324 err.span_label(expr.span, "for this argument");
326 "use the `{suggested_modifier}` modifier to have the register formatted as `{suggested_result}`",
329 "or use the `{default_modifier}` modifier to keep the default formatting of `{default_result}`",
340 pub fn check_asm(&self, asm: &hir::InlineAsm<'tcx>, enclosing_id: hir::HirId) {
341 let hir = self.tcx.hir();
342 let enclosing_def_id = hir.local_def_id(enclosing_id).to_def_id();
343 let target_features = self.tcx.asm_target_features(enclosing_def_id);
344 let Some(asm_arch) = self.tcx.sess.asm_arch else {
345 self.tcx.sess.delay_span_bug(DUMMY_SP, "target architecture does not support asm");
348 for (idx, (op, op_sp)) in asm.operands.iter().enumerate() {
349 // Validate register classes against currently enabled target
350 // features. We check that at least one type is available for
351 // the enabled features.
353 // We ignore target feature requirements for clobbers: if the
354 // feature is disabled then the compiler doesn't care what we
355 // do with the registers.
357 // Note that this is only possible for explicit register
358 // operands, which cannot be used in the asm string.
359 if let Some(reg) = op.reg() {
360 // Some explicit registers cannot be used depending on the
361 // target. Reject those here.
362 if let InlineAsmRegOrRegClass::Reg(reg) = reg {
363 if let InlineAsmReg::Err = reg {
364 // `validate` will panic on `Err`, as an error must
365 // already have been reported.
368 if let Err(msg) = reg.validate(
370 self.tcx.sess.relocation_model(),
372 &self.tcx.sess.target,
375 let msg = format!("cannot use register `{}`: {}", reg.name(), msg);
376 self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
381 if !op.is_clobber() {
382 let mut missing_required_features = vec![];
383 let reg_class = reg.reg_class();
384 if let InlineAsmRegClass::Err = reg_class {
387 for &(_, feature) in reg_class.supported_types(asm_arch) {
390 if target_features.contains(&feature) {
391 missing_required_features.clear();
394 missing_required_features.push(feature);
398 missing_required_features.clear();
404 // We are sorting primitive strs here and can use unstable sort here
405 missing_required_features.sort_unstable();
406 missing_required_features.dedup();
407 match &missing_required_features[..] {
411 "register class `{}` requires the `{}` target feature",
415 self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
416 // register isn't enabled, don't do more checks
421 "register class `{}` requires at least one of the following target features: {}",
427 .collect::<String>(),
429 self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
430 // register isn't enabled, don't do more checks
438 hir::InlineAsmOperand::In { reg, ref expr } => {
439 self.check_asm_operand_type(
449 hir::InlineAsmOperand::Out { reg, late: _, ref expr } => {
450 if let Some(expr) = expr {
451 self.check_asm_operand_type(
462 hir::InlineAsmOperand::InOut { reg, late: _, ref expr } => {
463 self.check_asm_operand_type(
473 hir::InlineAsmOperand::SplitInOut { reg, late: _, ref in_expr, ref out_expr } => {
474 let in_ty = self.check_asm_operand_type(
483 if let Some(out_expr) = out_expr {
484 self.check_asm_operand_type(
490 Some((in_expr, in_ty)),
495 // No special checking is needed for these:
496 // - Typeck has checked that Const operands are integers.
497 // - AST lowering guarantees that SymStatic points to a static.
498 hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymStatic { .. } => {}
499 // Check that sym actually points to a function. Later passes
501 hir::InlineAsmOperand::SymFn { anon_const } => {
502 let ty = self.tcx.typeck_body(anon_const.body).node_type(anon_const.hir_id);
504 ty::Never | ty::Error(_) => {}
508 self.tcx.sess.struct_span_err(*op_sp, "invalid `sym` operand");
510 self.tcx.hir().span(anon_const.body.hir_id),
511 &format!("is {} `{}`", ty.kind().article(), ty),
513 err.help("`sym` operands must refer to either a function or a static");