rustc_typeck to rustc_hir_analysis

compiler/rustc_hir_analysis/src/check/intrinsicck.rs

@@ -0,0 +1,531 @@
+use rustc_ast::InlineAsmTemplatePiece;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::struct_span_err;
+use rustc_hir as hir;
+use rustc_index::vec::Idx;
+use rustc_middle::ty::layout::{LayoutError, SizeSkeleton};
+use rustc_middle::ty::{self, Article, FloatTy, IntTy, Ty, TyCtxt, TypeVisitable, UintTy};
+use rustc_session::lint;
+use rustc_span::{Span, Symbol, DUMMY_SP};
+use rustc_target::abi::{Pointer, VariantIdx};
+use rustc_target::asm::{InlineAsmReg, InlineAsmRegClass, InlineAsmRegOrRegClass, InlineAsmType};
+
+use super::FnCtxt;
+
+/// If the type is `Option<T>`, it will return `T`, otherwise
+/// the type itself. Works on most `Option`-like types.
+fn unpack_option_like<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
+    let ty::Adt(def, substs) = *ty.kind() else { return ty };
+
+    if def.variants().len() == 2 && !def.repr().c() && def.repr().int.is_none() {
+        let data_idx;
+
+        let one = VariantIdx::new(1);
+        let zero = VariantIdx::new(0);
+
+        if def.variant(zero).fields.is_empty() {
+            data_idx = one;
+        } else if def.variant(one).fields.is_empty() {
+            data_idx = zero;
+        } else {
+            return ty;
+        }
+
+        if def.variant(data_idx).fields.len() == 1 {
+            return def.variant(data_idx).fields[0].ty(tcx, substs);
+        }
+    }
+
+    ty
+}
+
+impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+    pub fn check_transmute(&self, span: Span, from: Ty<'tcx>, to: Ty<'tcx>) {
+        let convert = |ty: Ty<'tcx>| {
+            let ty = self.resolve_vars_if_possible(ty);
+            let ty = self.tcx.normalize_erasing_regions(self.param_env, ty);
+            (SizeSkeleton::compute(ty, self.tcx, self.param_env), ty)
+        };
+        let (sk_from, from) = convert(from);
+        let (sk_to, to) = convert(to);
+
+        // Check for same size using the skeletons.
+        if let (Ok(sk_from), Ok(sk_to)) = (sk_from, sk_to) {
+            if sk_from.same_size(sk_to) {
+                return;
+            }
+
+            // Special-case transmuting from `typeof(function)` and
+            // `Option<typeof(function)>` to present a clearer error.
+            let from = unpack_option_like(self.tcx, from);
+            if let (&ty::FnDef(..), SizeSkeleton::Known(size_to)) = (from.kind(), sk_to) && size_to == Pointer.size(&self.tcx) {
+                struct_span_err!(self.tcx.sess, span, E0591, "can't transmute zero-sized type")
+                    .note(&format!("source type: {from}"))
+                    .note(&format!("target type: {to}"))
+                    .help("cast with `as` to a pointer instead")
+                    .emit();
+                return;
+            }
+        }
+
+        // Try to display a sensible error with as much information as possible.
+        let skeleton_string = |ty: Ty<'tcx>, sk| match sk {
+            Ok(SizeSkeleton::Known(size)) => format!("{} bits", size.bits()),
+            Ok(SizeSkeleton::Pointer { tail, .. }) => format!("pointer to `{tail}`"),
+            Err(LayoutError::Unknown(bad)) => {
+                if bad == ty {
+                    "this type does not have a fixed size".to_owned()
+                } else {
+                    format!("size can vary because of {bad}")
+                }
+            }
+            Err(err) => err.to_string(),
+        };
+
+        let mut err = struct_span_err!(
+            self.tcx.sess,
+            span,
+            E0512,
+            "cannot transmute between types of different sizes, \
+                                        or dependently-sized types"
+        );
+        if from == to {
+            err.note(&format!("`{from}` does not have a fixed size"));
+        } else {
+            err.note(&format!("source type: `{}` ({})", from, skeleton_string(from, sk_from)))
+                .note(&format!("target type: `{}` ({})", to, skeleton_string(to, sk_to)));
+        }
+        err.emit();
+    }
+}
+
+pub struct InlineAsmCtxt<'a, 'tcx> {
+    tcx: TyCtxt<'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
+    get_operand_ty: Box<dyn Fn(&'tcx hir::Expr<'tcx>) -> Ty<'tcx> + 'a>,
+}
+
+impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
+    pub fn new_global_asm(tcx: TyCtxt<'tcx>) -> Self {
+        InlineAsmCtxt {
+            tcx,
+            param_env: ty::ParamEnv::empty(),
+            get_operand_ty: Box::new(|e| bug!("asm operand in global asm: {e:?}")),
+        }
+    }
+
+    pub fn new_in_fn(
+        tcx: TyCtxt<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+        get_operand_ty: impl Fn(&'tcx hir::Expr<'tcx>) -> Ty<'tcx> + 'a,
+    ) -> Self {
+        InlineAsmCtxt { tcx, param_env, get_operand_ty: Box::new(get_operand_ty) }
+    }
+
+    // FIXME(compiler-errors): This could use `<$ty as Pointee>::Metadata == ()`
+    fn is_thin_ptr_ty(&self, ty: Ty<'tcx>) -> bool {
+        // Type still may have region variables, but `Sized` does not depend
+        // on those, so just erase them before querying.
+        if ty.is_sized(self.tcx.at(DUMMY_SP), self.param_env) {
+            return true;
+        }
+        if let ty::Foreign(..) = ty.kind() {
+            return true;
+        }
+        false
+    }
+
+    fn check_asm_operand_type(
+        &self,
+        idx: usize,
+        reg: InlineAsmRegOrRegClass,
+        expr: &'tcx hir::Expr<'tcx>,
+        template: &[InlineAsmTemplatePiece],
+        is_input: bool,
+        tied_input: Option<(&'tcx hir::Expr<'tcx>, Option<InlineAsmType>)>,
+        target_features: &FxHashSet<Symbol>,
+    ) -> Option<InlineAsmType> {
+        let ty = (self.get_operand_ty)(expr);
+        if ty.has_infer_types_or_consts() {
+            bug!("inference variable in asm operand ty: {:?} {:?}", expr, ty);
+        }
+        let asm_ty_isize = match self.tcx.sess.target.pointer_width {
+            16 => InlineAsmType::I16,
+            32 => InlineAsmType::I32,
+            64 => InlineAsmType::I64,
+            _ => unreachable!(),
+        };
+
+        let asm_ty = match *ty.kind() {
+            // `!` is allowed for input but not for output (issue #87802)
+            ty::Never if is_input => return None,
+            ty::Error(_) => return None,
+            ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Some(InlineAsmType::I8),
+            ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => Some(InlineAsmType::I16),
+            ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => Some(InlineAsmType::I32),
+            ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => Some(InlineAsmType::I64),
+            ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => Some(InlineAsmType::I128),
+            ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => Some(asm_ty_isize),
+            ty::Float(FloatTy::F32) => Some(InlineAsmType::F32),
+            ty::Float(FloatTy::F64) => Some(InlineAsmType::F64),
+            ty::FnPtr(_) => Some(asm_ty_isize),
+            ty::RawPtr(ty::TypeAndMut { ty, mutbl: _ }) if self.is_thin_ptr_ty(ty) => {
+                Some(asm_ty_isize)
+            }
+            ty::Adt(adt, substs) if adt.repr().simd() => {
+                let fields = &adt.non_enum_variant().fields;
+                let elem_ty = fields[0].ty(self.tcx, substs);
+                match elem_ty.kind() {
+                    ty::Never | ty::Error(_) => return None,
+                    ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => {
+                        Some(InlineAsmType::VecI8(fields.len() as u64))
+                    }
+                    ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => {
+                        Some(InlineAsmType::VecI16(fields.len() as u64))
+                    }
+                    ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => {
+                        Some(InlineAsmType::VecI32(fields.len() as u64))
+                    }
+                    ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => {
+                        Some(InlineAsmType::VecI64(fields.len() as u64))
+                    }
+                    ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => {
+                        Some(InlineAsmType::VecI128(fields.len() as u64))
+                    }
+                    ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => {
+                        Some(match self.tcx.sess.target.pointer_width {
+                            16 => InlineAsmType::VecI16(fields.len() as u64),
+                            32 => InlineAsmType::VecI32(fields.len() as u64),
+                            64 => InlineAsmType::VecI64(fields.len() as u64),
+                            _ => unreachable!(),
+                        })
+                    }
+                    ty::Float(FloatTy::F32) => Some(InlineAsmType::VecF32(fields.len() as u64)),
+                    ty::Float(FloatTy::F64) => Some(InlineAsmType::VecF64(fields.len() as u64)),
+                    _ => None,
+                }
+            }
+            ty::Infer(_) => unreachable!(),
+            _ => None,
+        };
+        let Some(asm_ty) = asm_ty else {
+            let msg = &format!("cannot use value of type `{ty}` for inline assembly");
+            let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
+            err.note(
+                "only integers, floats, SIMD vectors, pointers and function pointers \
+                 can be used as arguments for inline assembly",
+            );
+            err.emit();
+            return None;
+        };
+
+        // Check that the type implements Copy. The only case where this can
+        // possibly fail is for SIMD types which don't #[derive(Copy)].
+        if !ty.is_copy_modulo_regions(self.tcx.at(expr.span), self.param_env) {
+            let msg = "arguments for inline assembly must be copyable";
+            let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
+            err.note(&format!("`{ty}` does not implement the Copy trait"));
+            err.emit();
+        }
+
+        // Ideally we wouldn't need to do this, but LLVM's register allocator
+        // really doesn't like it when tied operands have different types.
+        //
+        // This is purely an LLVM limitation, but we have to live with it since
+        // there is no way to hide this with implicit conversions.
+        //
+        // For the purposes of this check we only look at the `InlineAsmType`,
+        // which means that pointers and integers are treated as identical (modulo
+        // size).
+        if let Some((in_expr, Some(in_asm_ty))) = tied_input {
+            if in_asm_ty != asm_ty {
+                let msg = "incompatible types for asm inout argument";
+                let mut err = self.tcx.sess.struct_span_err(vec![in_expr.span, expr.span], msg);
+
+                let in_expr_ty = (self.get_operand_ty)(in_expr);
+                err.span_label(in_expr.span, &format!("type `{in_expr_ty}`"));
+                err.span_label(expr.span, &format!("type `{ty}`"));
+                err.note(
+                    "asm inout arguments must have the same type, \
+                    unless they are both pointers or integers of the same size",
+                );
+                err.emit();
+            }
+
+            // All of the later checks have already been done on the input, so
+            // let's not emit errors and warnings twice.
+            return Some(asm_ty);
+        }
+
+        // Check the type against the list of types supported by the selected
+        // register class.
+        let asm_arch = self.tcx.sess.asm_arch.unwrap();
+        let reg_class = reg.reg_class();
+        let supported_tys = reg_class.supported_types(asm_arch);
+        let Some((_, feature)) = supported_tys.iter().find(|&&(t, _)| t == asm_ty) else {
+            let msg = &format!("type `{ty}` cannot be used with this register class");
+            let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
+            let supported_tys: Vec<_> =
+                supported_tys.iter().map(|(t, _)| t.to_string()).collect();
+            err.note(&format!(
+                "register class `{}` supports these types: {}",
+                reg_class.name(),
+                supported_tys.join(", "),
+            ));
+            if let Some(suggest) = reg_class.suggest_class(asm_arch, asm_ty) {
+                err.help(&format!(
+                    "consider using the `{}` register class instead",
+                    suggest.name()
+                ));
+            }
+            err.emit();
+            return Some(asm_ty);
+        };
+
+        // Check whether the selected type requires a target feature. Note that
+        // this is different from the feature check we did earlier. While the
+        // previous check checked that this register class is usable at all
+        // with the currently enabled features, some types may only be usable
+        // with a register class when a certain feature is enabled. We check
+        // this here since it depends on the results of typeck.
+        //
+        // Also note that this check isn't run when the operand type is never
+        // (!). In that case we still need the earlier check to verify that the
+        // register class is usable at all.
+        if let Some(feature) = feature {
+            if !target_features.contains(&feature) {
+                let msg = &format!("`{}` target feature is not enabled", feature);
+                let mut err = self.tcx.sess.struct_span_err(expr.span, msg);
+                err.note(&format!(
+                    "this is required to use type `{}` with register class `{}`",
+                    ty,
+                    reg_class.name(),
+                ));
+                err.emit();
+                return Some(asm_ty);
+            }
+        }
+
+        // Check whether a modifier is suggested for using this type.
+        if let Some((suggested_modifier, suggested_result)) =
+            reg_class.suggest_modifier(asm_arch, asm_ty)
+        {
+            // Search for any use of this operand without a modifier and emit
+            // the suggestion for them.
+            let mut spans = vec![];
+            for piece in template {
+                if let &InlineAsmTemplatePiece::Placeholder { operand_idx, modifier, span } = piece
+                {
+                    if operand_idx == idx && modifier.is_none() {
+                        spans.push(span);
+                    }
+                }
+            }
+            if !spans.is_empty() {
+                let (default_modifier, default_result) =
+                    reg_class.default_modifier(asm_arch).unwrap();
+                self.tcx.struct_span_lint_hir(
+                    lint::builtin::ASM_SUB_REGISTER,
+                    expr.hir_id,
+                    spans,
+                    |lint| {
+                        let msg = "formatting may not be suitable for sub-register argument";
+                        let mut err = lint.build(msg);
+                        err.span_label(expr.span, "for this argument");
+                        err.help(&format!(
+                            "use `{{{idx}:{suggested_modifier}}}` to have the register formatted as `{suggested_result}`",
+                        ));
+                        err.help(&format!(
+                            "or use `{{{idx}:{default_modifier}}}` to keep the default formatting of `{default_result}`",
+                        ));
+                        err.emit();
+                    },
+                );
+            }
+        }
+
+        Some(asm_ty)
+    }
+
+    pub fn check_asm(&self, asm: &hir::InlineAsm<'tcx>, enclosing_id: hir::HirId) {
+        let hir = self.tcx.hir();
+        let enclosing_def_id = hir.local_def_id(enclosing_id).to_def_id();
+        let target_features = self.tcx.asm_target_features(enclosing_def_id);
+        let Some(asm_arch) = self.tcx.sess.asm_arch else {
+            self.tcx.sess.delay_span_bug(DUMMY_SP, "target architecture does not support asm");
+            return;
+        };
+        for (idx, (op, op_sp)) in asm.operands.iter().enumerate() {
+            // Validate register classes against currently enabled target
+            // features. We check that at least one type is available for
+            // the enabled features.
+            //
+            // We ignore target feature requirements for clobbers: if the
+            // feature is disabled then the compiler doesn't care what we
+            // do with the registers.
+            //
+            // Note that this is only possible for explicit register
+            // operands, which cannot be used in the asm string.
+            if let Some(reg) = op.reg() {
+                // Some explicit registers cannot be used depending on the
+                // target. Reject those here.
+                if let InlineAsmRegOrRegClass::Reg(reg) = reg {
+                    if let InlineAsmReg::Err = reg {
+                        // `validate` will panic on `Err`, as an error must
+                        // already have been reported.
+                        continue;
+                    }
+                    if let Err(msg) = reg.validate(
+                        asm_arch,
+                        self.tcx.sess.relocation_model(),
+                        &target_features,
+                        &self.tcx.sess.target,
+                        op.is_clobber(),
+                    ) {
+                        let msg = format!("cannot use register `{}`: {}", reg.name(), msg);
+                        self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
+                        continue;
+                    }
+                }
+
+                if !op.is_clobber() {
+                    let mut missing_required_features = vec![];
+                    let reg_class = reg.reg_class();
+                    if let InlineAsmRegClass::Err = reg_class {
+                        continue;
+                    }
+                    for &(_, feature) in reg_class.supported_types(asm_arch) {
+                        match feature {
+                            Some(feature) => {
+                                if target_features.contains(&feature) {
+                                    missing_required_features.clear();
+                                    break;
+                                } else {
+                                    missing_required_features.push(feature);
+                                }
+                            }
+                            None => {
+                                missing_required_features.clear();
+                                break;
+                            }
+                        }
+                    }
+
+                    // We are sorting primitive strs here and can use unstable sort here
+                    missing_required_features.sort_unstable();
+                    missing_required_features.dedup();
+                    match &missing_required_features[..] {
+                        [] => {}
+                        [feature] => {
+                            let msg = format!(
+                                "register class `{}` requires the `{}` target feature",
+                                reg_class.name(),
+                                feature
+                            );
+                            self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
+                            // register isn't enabled, don't do more checks
+                            continue;
+                        }
+                        features => {
+                            let msg = format!(
+                                "register class `{}` requires at least one of the following target features: {}",
+                                reg_class.name(),
+                                features
+                                    .iter()
+                                    .map(|f| f.as_str())
+                                    .intersperse(", ")
+                                    .collect::<String>(),
+                            );
+                            self.tcx.sess.struct_span_err(*op_sp, &msg).emit();
+                            // register isn't enabled, don't do more checks
+                            continue;
+                        }
+                    }
+                }
+            }
+
+            match *op {
+                hir::InlineAsmOperand::In { reg, ref expr } => {
+                    self.check_asm_operand_type(
+                        idx,
+                        reg,
+                        expr,
+                        asm.template,
+                        true,
+                        None,
+                        &target_features,
+                    );
+                }
+                hir::InlineAsmOperand::Out { reg, late: _, ref expr } => {
+                    if let Some(expr) = expr {
+                        self.check_asm_operand_type(
+                            idx,
+                            reg,
+                            expr,
+                            asm.template,
+                            false,
+                            None,
+                            &target_features,
+                        );
+                    }
+                }
+                hir::InlineAsmOperand::InOut { reg, late: _, ref expr } => {
+                    self.check_asm_operand_type(
+                        idx,
+                        reg,
+                        expr,
+                        asm.template,
+                        false,
+                        None,
+                        &target_features,
+                    );
+                }
+                hir::InlineAsmOperand::SplitInOut { reg, late: _, ref in_expr, ref out_expr } => {
+                    let in_ty = self.check_asm_operand_type(
+                        idx,
+                        reg,
+                        in_expr,
+                        asm.template,
+                        true,
+                        None,
+                        &target_features,
+                    );
+                    if let Some(out_expr) = out_expr {
+                        self.check_asm_operand_type(
+                            idx,
+                            reg,
+                            out_expr,
+                            asm.template,
+                            false,
+                            Some((in_expr, in_ty)),
+                            &target_features,
+                        );
+                    }
+                }
+                // No special checking is needed for these:
+                // - Typeck has checked that Const operands are integers.
+                // - AST lowering guarantees that SymStatic points to a static.
+                hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymStatic { .. } => {}
+                // Check that sym actually points to a function. Later passes
+                // depend on this.
+                hir::InlineAsmOperand::SymFn { anon_const } => {
+                    let ty = self.tcx.typeck_body(anon_const.body).node_type(anon_const.hir_id);
+                    match ty.kind() {
+                        ty::Never | ty::Error(_) => {}
+                        ty::FnDef(..) => {}
+                        _ => {
+                            let mut err =
+                                self.tcx.sess.struct_span_err(*op_sp, "invalid `sym` operand");
+                            err.span_label(
+                                self.tcx.hir().span(anon_const.body.hir_id),
+                                &format!("is {} `{}`", ty.kind().article(), ty),
+                            );
+                            err.help("`sym` operands must refer to either a function or a static");
+                            err.emit();
+                        }
+                    };
+                }
+            }
+        }
+    }
+}