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CFI: Support self_cell-like recursion
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Current `transform_ty` attempts to avoid cycles when normalizing
`#[repr(transparent)]` types to their interior, but runs afoul of this
pattern used in `self_cell`:

```
struct X<T> {
  x: u8,
  p: PhantomData<T>,
}

 #[repr(transparent)]
struct Y(X<Y>);
```

When attempting to normalize Y, it will still cycle indefinitely. By
using a types-visited list, this will instead get expanded exactly
one layer deep to X<Y>, and then stop, not attempting to normalize `Y`
any further.
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@maurer
maurer committed Mar 22, 2024
1 parent 85e449a commit dec36c3
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Showing 3 changed files with 94 additions and 25 deletions.
70 changes: 45 additions & 25 deletions compiler/rustc_symbol_mangling/src/typeid/typeid_itanium_cxx_abi.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -178,14 +178,14 @@ fn encode_fnsig<'tcx>(
// Encode the return type
let transform_ty_options = TransformTyOptions::from_bits(options.bits())
.unwrap_or_else(|| bug!("encode_fnsig: invalid option(s) `{:?}`", options.bits()));
let ty = transform_ty(tcx, fn_sig.output(), transform_ty_options);
let ty = transform_ty(tcx, fn_sig.output(), &mut Vec::new(), transform_ty_options);
s.push_str(&encode_ty(tcx, ty, dict, encode_ty_options));

// Encode the parameter types
let tys = fn_sig.inputs();
if !tys.is_empty() {
for ty in tys {
let ty = transform_ty(tcx, *ty, transform_ty_options);
let ty = transform_ty(tcx, *ty, &mut Vec::new(), transform_ty_options);
s.push_str(&encode_ty(tcx, ty, dict, encode_ty_options));
}

Expand Down Expand Up @@ -767,11 +767,12 @@ fn transform_predicates<'tcx>(
fn transform_args<'tcx>(
tcx: TyCtxt<'tcx>,
args: GenericArgsRef<'tcx>,
parents: &mut Vec<Ty<'tcx>>,
options: TransformTyOptions,
) -> GenericArgsRef<'tcx> {
let args = args.iter().map(|arg| match arg.unpack() {
GenericArgKind::Type(ty) if ty.is_c_void(tcx) => Ty::new_unit(tcx).into(),
GenericArgKind::Type(ty) => transform_ty(tcx, ty, options).into(),
GenericArgKind::Type(ty) => transform_ty(tcx, ty, parents, options).into(),
_ => arg,
});
tcx.mk_args_from_iter(args)
Expand All @@ -781,9 +782,12 @@ fn transform_args<'tcx>(
// c_void types into unit types unconditionally, generalizes pointers if
// TransformTyOptions::GENERALIZE_POINTERS option is set, and normalizes integers if
// TransformTyOptions::NORMALIZE_INTEGERS option is set.
fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptions) -> Ty<'tcx> {
let mut ty = ty;

fn transform_ty<'tcx>(
tcx: TyCtxt<'tcx>,
mut ty: Ty<'tcx>,
parents: &mut Vec<Ty<'tcx>>,
options: TransformTyOptions,
) -> Ty<'tcx> {
match ty.kind() {
ty::Float(..) | ty::Str | ty::Never | ty::Foreign(..) | ty::CoroutineWitness(..) => {}

Expand Down Expand Up @@ -843,17 +847,20 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
_ if ty.is_unit() => {}

ty::Tuple(tys) => {
ty = Ty::new_tup_from_iter(tcx, tys.iter().map(|ty| transform_ty(tcx, ty, options)));
ty = Ty::new_tup_from_iter(
tcx,
tys.iter().map(|ty| transform_ty(tcx, ty, parents, options)),
);
}

ty::Array(ty0, len) => {
let len = len.eval_target_usize(tcx, ty::ParamEnv::reveal_all());

ty = Ty::new_array(tcx, transform_ty(tcx, *ty0, options), len);
ty = Ty::new_array(tcx, transform_ty(tcx, *ty0, parents, options), len);
}

ty::Slice(ty0) => {
ty = Ty::new_slice(tcx, transform_ty(tcx, *ty0, options));
ty = Ty::new_slice(tcx, transform_ty(tcx, *ty0, parents, options));
}

ty::Adt(adt_def, args) => {
Expand All @@ -862,7 +869,8 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
} else if options.contains(TransformTyOptions::GENERALIZE_REPR_C) && adt_def.repr().c()
{
ty = Ty::new_adt(tcx, *adt_def, ty::List::empty());
} else if adt_def.repr().transparent() && adt_def.is_struct() {
} else if adt_def.repr().transparent() && adt_def.is_struct() && !parents.contains(&ty)
{
// Don't transform repr(transparent) types with an user-defined CFI encoding to
// preserve the user-defined CFI encoding.
if let Some(_) = tcx.get_attr(adt_def.did(), sym::cfi_encoding) {
Expand All @@ -881,38 +889,48 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
// Generalize any repr(transparent) user-defined type that is either a pointer
// or reference, and either references itself or any other type that contains or
// references itself, to avoid a reference cycle.

// If the self reference is not through a pointer, for example, due
// to using `PhantomData`, need to skip normalizing it if we hit it again.
parents.push(ty);
if ty0.is_any_ptr() && ty0.contains(ty) {
ty = transform_ty(
tcx,
ty0,
parents,
options | TransformTyOptions::GENERALIZE_POINTERS,
);
} else {
ty = transform_ty(tcx, ty0, options);
ty = transform_ty(tcx, ty0, parents, options);
}
parents.pop();
} else {
// Transform repr(transparent) types without non-ZST field into ()
ty = Ty::new_unit(tcx);
}
} else {
ty = Ty::new_adt(tcx, *adt_def, transform_args(tcx, args, options));
ty = Ty::new_adt(tcx, *adt_def, transform_args(tcx, args, parents, options));
}
}

ty::FnDef(def_id, args) => {
ty = Ty::new_fn_def(tcx, *def_id, transform_args(tcx, args, options));
ty = Ty::new_fn_def(tcx, *def_id, transform_args(tcx, args, parents, options));
}

ty::Closure(def_id, args) => {
ty = Ty::new_closure(tcx, *def_id, transform_args(tcx, args, options));
ty = Ty::new_closure(tcx, *def_id, transform_args(tcx, args, parents, options));
}

ty::CoroutineClosure(def_id, args) => {
ty = Ty::new_coroutine_closure(tcx, *def_id, transform_args(tcx, args, options));
ty = Ty::new_coroutine_closure(
tcx,
*def_id,
transform_args(tcx, args, parents, options),
);
}

ty::Coroutine(def_id, args) => {
ty = Ty::new_coroutine(tcx, *def_id, transform_args(tcx, args, options));
ty = Ty::new_coroutine(tcx, *def_id, transform_args(tcx, args, parents, options));
}

ty::Ref(region, ty0, ..) => {
Expand All @@ -924,9 +942,9 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
}
} else {
if ty.is_mutable_ptr() {
ty = Ty::new_mut_ref(tcx, *region, transform_ty(tcx, *ty0, options));
ty = Ty::new_mut_ref(tcx, *region, transform_ty(tcx, *ty0, parents, options));
} else {
ty = Ty::new_imm_ref(tcx, *region, transform_ty(tcx, *ty0, options));
ty = Ty::new_imm_ref(tcx, *region, transform_ty(tcx, *ty0, parents, options));
}
}
}
Expand All @@ -940,9 +958,9 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
}
} else {
if ty.is_mutable_ptr() {
ty = Ty::new_mut_ptr(tcx, transform_ty(tcx, *ptr_ty, options));
ty = Ty::new_mut_ptr(tcx, transform_ty(tcx, *ptr_ty, parents, options));
} else {
ty = Ty::new_imm_ptr(tcx, transform_ty(tcx, *ptr_ty, options));
ty = Ty::new_imm_ptr(tcx, transform_ty(tcx, *ptr_ty, parents, options));
}
}
}
Expand All @@ -955,9 +973,9 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
.skip_binder()
.inputs()
.iter()
.map(|ty| transform_ty(tcx, *ty, options))
.map(|ty| transform_ty(tcx, *ty, parents, options))
.collect();
let output = transform_ty(tcx, fn_sig.skip_binder().output(), options);
let output = transform_ty(tcx, fn_sig.skip_binder().output(), parents, options);
ty = Ty::new_fn_ptr(
tcx,
ty::Binder::bind_with_vars(
Expand Down Expand Up @@ -987,6 +1005,7 @@ fn transform_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, options: TransformTyOptio
ty = transform_ty(
tcx,
tcx.normalize_erasing_regions(ty::ParamEnv::reveal_all(), ty),
parents,
options,
);
}
Expand Down Expand Up @@ -1037,7 +1056,7 @@ pub fn typeid_for_fnabi<'tcx>(
// Encode the return type
let transform_ty_options = TransformTyOptions::from_bits(options.bits())
.unwrap_or_else(|| bug!("typeid_for_fnabi: invalid option(s) `{:?}`", options.bits()));
let ty = transform_ty(tcx, fn_abi.ret.layout.ty, transform_ty_options);
let ty = transform_ty(tcx, fn_abi.ret.layout.ty, &mut Vec::new(), transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));

// Encode the parameter types
Expand All @@ -1049,7 +1068,7 @@ pub fn typeid_for_fnabi<'tcx>(
let mut pushed_arg = false;
for arg in fn_abi.args.iter().filter(|arg| arg.mode != PassMode::Ignore) {
pushed_arg = true;
let ty = transform_ty(tcx, arg.layout.ty, transform_ty_options);
let ty = transform_ty(tcx, arg.layout.ty, &mut Vec::new(), transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
}
if !pushed_arg {
Expand All @@ -1062,7 +1081,8 @@ pub fn typeid_for_fnabi<'tcx>(
if fn_abi.args[n].mode == PassMode::Ignore {
continue;
}
let ty = transform_ty(tcx, fn_abi.args[n].layout.ty, transform_ty_options);
let ty =
transform_ty(tcx, fn_abi.args[n].layout.ty, &mut Vec::new(), transform_ty_options);
typeid.push_str(&encode_ty(tcx, ty, &mut dict, encode_ty_options));
}

Expand Down
16 changes: 16 additions & 0 deletions tests/codegen/sanitizer/cfi/emit-type-metadata-id-itanium-cxx-abi-repr-transparent-types.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,12 @@ pub struct Bar(i32);
#[repr(transparent)]
pub struct Type3<T>(T);

// repr(transparent) wrapper which engages in self-reference
#[repr(transparent)]
pub struct Type4(Type4Helper<Type4>);
#[repr(transparent)]
pub struct Type4Helper<T>(*mut T);

pub fn foo1(_: Type1) { }
// CHECK: define{{.*}}4foo1{{.*}}!type ![[TYPE1:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
pub fn foo2(_: Type1, _: Type1) { }
Expand All @@ -52,6 +58,13 @@ pub fn foo8(_: Type3<Bar>, _: Type3<Bar>) { }
// CHECK: define{{.*}}4foo8{{.*}}!type ![[TYPE8:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
pub fn foo9(_: Type3<Bar>, _: Type3<Bar>, _: Type3<Bar>) { }
// CHECK: define{{.*}}4foo9{{.*}}!type ![[TYPE9:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
pub fn foo10(_: Type4) { }
// CHECK: define{{.*}}5foo10{{.*}}!type ![[TYPE10:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
pub fn foo11(_: Type4, _: Type4) { }
// CHECK: define{{.*}}5foo11{{.*}}!type ![[TYPE11:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}
pub fn foo12(_: Type4, _: Type4, _: Type4) { }
// CHECK: define{{.*}}5foo12{{.*}}!type ![[TYPE12:[0-9]+]] !type !{{[0-9]+}} !type !{{[0-9]+}} !type !{{[0-9]+}}


// CHECK: ![[TYPE1]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}3FooE"}
// CHECK: ![[TYPE2]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}3FooS_E"}
Expand All @@ -62,3 +75,6 @@ pub fn foo9(_: Type3<Bar>, _: Type3<Bar>, _: Type3<Bar>) { }
// CHECK: ![[TYPE7]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}3BarE"}
// CHECK: ![[TYPE8]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}3BarS_E"}
// CHECK: ![[TYPE9]] = !{i64 0, !"_ZTSFvu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}3BarS_S_E"}
// CHECK: ![[TYPE10]] = !{i64 0, !"_ZTSFvPu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}5Type4E"}
// CHECK: ![[TYPE11]] = !{i64 0, !"_ZTSFvPu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}5Type4S0_E"}
// CHECK: ![[TYPE12]] = !{i64 0, !"_ZTSFvPu{{[0-9]+}}NtC{{[[:print:]]+}}_{{[[:print:]]+}}5Type4S0_S0_E"}
33 changes: 33 additions & 0 deletions tests/ui/sanitizer/cfi-self-ref.rs
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
// Check that encoding self-referential types works with #[repr(transparent)]

//@ needs-sanitizer-cfi
// FIXME(#122848) Remove only-linux once OSX CFI binaries work
//@ only-linux
//@ compile-flags: --crate-type=bin -Cprefer-dynamic=off -Clto -Zsanitizer=cfi
//@ compile-flags: -C target-feature=-crt-static -C codegen-units=1 -C opt-level=0
//@ run-pass

use std::marker::PhantomData;

struct X<T> {
_x: u8,
p: PhantomData<T>,
}

#[repr(transparent)]
struct Y(X<Y>);

trait Fooable {
fn foo(&self, y: Y);
}

struct Bar;

impl Fooable for Bar {
fn foo(&self, _: Y) {}
}

fn main() {
let x = &Bar as &dyn Fooable;
x.foo(Y(X {_x: 0, p: PhantomData}));
}

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