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use rustc_ast::InlineAsmTemplatePiece;
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir as hir;
use rustc_middle::ty::{self, Article, FloatTy, IntTy, Ty, TyCtxt, TypeVisitableExt, UintTy};
use rustc_session::lint;
use rustc_span::def_id::LocalDefId;
use rustc_span::{Symbol, DUMMY_SP};
use rustc_target::abi::FieldIdx;
use rustc_target::asm::{InlineAsmReg, InlineAsmRegClass, InlineAsmRegOrRegClass, InlineAsmType};
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, self.param_env) {
return true;
}
if let ty::Foreign(..) = ty.kind() {
return true;
}
false
}
fn get_asm_ty(&self, ty: Ty<'tcx>) -> Option<InlineAsmType> {
let asm_ty_isize = match self.tcx.sess.target.pointer_width {
16 => InlineAsmType::I16,
32 => InlineAsmType::I32,
64 => InlineAsmType::I64,
_ => unreachable!(),
};
match *ty.kind() {
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, args) if adt.repr().simd() => {
let fields = &adt.non_enum_variant().fields;
let elem_ty = fields[FieldIdx::from_u32(0)].ty(self.tcx, args);
let (size, ty) = match elem_ty.kind() {
ty::Array(ty, len) => {
if let Some(len) =
len.try_eval_target_usize(self.tcx, self.tcx.param_env(adt.did()))
{
(len, *ty)
} else {
return None;
}
}
_ => (fields.len() as u64, elem_ty),
};
match ty.kind() {
ty::Int(IntTy::I8) | ty::Uint(UintTy::U8) => Some(InlineAsmType::VecI8(size)),
ty::Int(IntTy::I16) | ty::Uint(UintTy::U16) => {
Some(InlineAsmType::VecI16(size))
}
ty::Int(IntTy::I32) | ty::Uint(UintTy::U32) => {
Some(InlineAsmType::VecI32(size))
}
ty::Int(IntTy::I64) | ty::Uint(UintTy::U64) => {
Some(InlineAsmType::VecI64(size))
}
ty::Int(IntTy::I128) | ty::Uint(UintTy::U128) => {
Some(InlineAsmType::VecI128(size))
}
ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => {
Some(match self.tcx.sess.target.pointer_width {
16 => InlineAsmType::VecI16(size),
32 => InlineAsmType::VecI32(size),
64 => InlineAsmType::VecI64(size),
_ => unreachable!(),
})
}
ty::Float(FloatTy::F32) => Some(InlineAsmType::VecF32(size)),
ty::Float(FloatTy::F64) => Some(InlineAsmType::VecF64(size)),
_ => None,
}
}
ty::Infer(_) => unreachable!(),
_ => None,
}
}
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: &FxIndexSet<Symbol>,
) -> Option<InlineAsmType> {
let ty = (self.get_operand_ty)(expr);
if ty.has_non_region_infer() {
bug!("inference variable in asm operand ty: {:?} {:?}", expr, ty);
}
let asm_ty = match *ty.kind() {
// `!` is allowed for input but not for output (issue #87802)
ty::Never if is_input => return None,
_ if ty.references_error() => return None,
ty::Adt(adt, args) if Some(adt.did()) == self.tcx.lang_items().maybe_uninit() => {
let fields = &adt.non_enum_variant().fields;
let ty = fields[FieldIdx::from_u32(1)].ty(self.tcx, args);
let ty::Adt(ty, args) = ty.kind() else { unreachable!() };
assert!(ty.is_manually_drop());
let fields = &ty.non_enum_variant().fields;
let ty = fields[FieldIdx::from_u32(0)].ty(self.tcx, args);
self.get_asm_ty(ty)
}
_ => self.get_asm_ty(ty),
};
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, 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!("`{feature}` target feature is not enabled");
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,
"formatting may not be suitable for sub-register argument",
|lint| {
lint.span_label(expr.span, "for this argument");
lint.help(format!(
"use `{{{idx}:{suggested_modifier}}}` to have the register formatted as `{suggested_result}`",
));
lint.help(format!(
"or use `{{{idx}:{default_modifier}}}` to keep the default formatting of `{default_result}`",
));
lint
},
);
}
}
Some(asm_ty)
}
pub fn check_asm(&self, asm: &hir::InlineAsm<'tcx>, enclosing_id: LocalDefId) {
let target_features = self.tcx.asm_target_features(enclosing_id.to_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, expr } => {
self.check_asm_operand_type(
idx,
reg,
expr,
asm.template,
true,
None,
&target_features,
);
}
hir::InlineAsmOperand::Out { reg, late: _, 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: _, expr } => {
self.check_asm_operand_type(
idx,
reg,
expr,
asm.template,
false,
None,
&target_features,
);
}
hir::InlineAsmOperand::SplitInOut { reg, late: _, in_expr, 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.type_of(anon_const.def_id).instantiate_identity();
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.def_span(anon_const.def_id),
format!("is {} `{}`", ty.kind().article(), ty),
);
err.help("`sym` operands must refer to either a function or a static");
err.emit();
}
};
}
}
}
}
}