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use std::borrow::Cow;
use either::Either;
use rustc_ast::ast::InlineAsmOptions;
use rustc_middle::{
mir,
ty::{
self,
layout::{FnAbiOf, IntegerExt, LayoutOf, TyAndLayout},
AdtDef, Instance, Ty,
},
};
use rustc_span::sym;
use rustc_target::abi::{self, FieldIdx};
use rustc_target::abi::{
call::{ArgAbi, FnAbi, PassMode},
Integer,
};
use rustc_target::spec::abi::Abi;
use super::{
AllocId, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy, Projectable,
Provenance, Scalar, StackPopCleanup,
};
use crate::fluent_generated as fluent;
/// An argment passed to a function.
#[derive(Clone, Debug)]
pub enum FnArg<'tcx, Prov: Provenance = AllocId> {
/// Pass a copy of the given operand.
Copy(OpTy<'tcx, Prov>),
/// Allow for the argument to be passed in-place: destroy the value originally stored at that place and
/// make the place inaccessible for the duration of the function call.
InPlace(PlaceTy<'tcx, Prov>),
}
impl<'tcx, Prov: Provenance> FnArg<'tcx, Prov> {
pub fn layout(&self) -> &TyAndLayout<'tcx> {
match self {
FnArg::Copy(op) => &op.layout,
FnArg::InPlace(place) => &place.layout,
}
}
}
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// Make a copy of the given fn_arg. Any `InPlace` are degenerated to copies, no protection of the
/// original memory occurs.
pub fn copy_fn_arg(
&self,
arg: &FnArg<'tcx, M::Provenance>,
) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
match arg {
FnArg::Copy(op) => Ok(op.clone()),
FnArg::InPlace(place) => self.place_to_op(&place),
}
}
/// Make a copy of the given fn_args. Any `InPlace` are degenerated to copies, no protection of the
/// original memory occurs.
pub fn copy_fn_args(
&self,
args: &[FnArg<'tcx, M::Provenance>],
) -> InterpResult<'tcx, Vec<OpTy<'tcx, M::Provenance>>> {
args.iter().map(|fn_arg| self.copy_fn_arg(fn_arg)).collect()
}
pub fn fn_arg_field(
&self,
arg: &FnArg<'tcx, M::Provenance>,
field: usize,
) -> InterpResult<'tcx, FnArg<'tcx, M::Provenance>> {
Ok(match arg {
FnArg::Copy(op) => FnArg::Copy(self.project_field(op, field)?),
FnArg::InPlace(place) => FnArg::InPlace(self.project_field(place, field)?),
})
}
pub(super) fn eval_terminator(
&mut self,
terminator: &mir::Terminator<'tcx>,
) -> InterpResult<'tcx> {
use rustc_middle::mir::TerminatorKind::*;
match terminator.kind {
Return => {
self.pop_stack_frame(/* unwinding */ false)?
}
Goto { target } => self.go_to_block(target),
SwitchInt { ref discr, ref targets } => {
let discr = self.read_immediate(&self.eval_operand(discr, None)?)?;
trace!("SwitchInt({:?})", *discr);
// Branch to the `otherwise` case by default, if no match is found.
let mut target_block = targets.otherwise();
for (const_int, target) in targets.iter() {
// Compare using MIR BinOp::Eq, to also support pointer values.
// (Avoiding `self.binary_op` as that does some redundant layout computation.)
let res = self.wrapping_binary_op(
mir::BinOp::Eq,
&discr,
&ImmTy::from_uint(const_int, discr.layout),
)?;
if res.to_scalar().to_bool()? {
target_block = target;
break;
}
}
self.go_to_block(target_block);
}
Call {
ref func,
ref args,
destination,
target,
unwind,
call_source: _,
fn_span: _,
} => {
let old_stack = self.frame_idx();
let old_loc = self.frame().loc;
let func = self.eval_operand(func, None)?;
let args = self.eval_fn_call_arguments(args)?;
let fn_sig_binder = func.layout.ty.fn_sig(*self.tcx);
let fn_sig =
self.tcx.normalize_erasing_late_bound_regions(self.param_env, fn_sig_binder);
let extra_args = &args[fn_sig.inputs().len()..];
let extra_args =
self.tcx.mk_type_list_from_iter(extra_args.iter().map(|arg| arg.layout().ty));
let (fn_val, fn_abi, with_caller_location) = match *func.layout.ty.kind() {
ty::FnPtr(_sig) => {
let fn_ptr = self.read_pointer(&func)?;
let fn_val = self.get_ptr_fn(fn_ptr)?;
(fn_val, self.fn_abi_of_fn_ptr(fn_sig_binder, extra_args)?, false)
}
ty::FnDef(def_id, args) => {
let instance = self.resolve(def_id, args)?;
(
FnVal::Instance(instance),
self.fn_abi_of_instance(instance, extra_args)?,
instance.def.requires_caller_location(*self.tcx),
)
}
_ => span_bug!(
terminator.source_info.span,
"invalid callee of type {}",
func.layout.ty
),
};
let destination = self.eval_place(destination)?;
self.eval_fn_call(
fn_val,
(fn_sig.abi, fn_abi),
&args,
with_caller_location,
&destination,
target,
if fn_abi.can_unwind { unwind } else { mir::UnwindAction::Unreachable },
)?;
// Sanity-check that `eval_fn_call` either pushed a new frame or
// did a jump to another block.
if self.frame_idx() == old_stack && self.frame().loc == old_loc {
span_bug!(terminator.source_info.span, "evaluating this call made no progress");
}
}
Drop { place, target, unwind, replace: _ } => {
let frame = self.frame();
let ty = place.ty(&frame.body.local_decls, *self.tcx).ty;
let ty = self.subst_from_frame_and_normalize_erasing_regions(frame, ty)?;
let instance = Instance::resolve_drop_in_place(*self.tcx, ty);
if let ty::InstanceDef::DropGlue(_, None) = instance.def {
// This is the branch we enter if and only if the dropped type has no drop glue
// whatsoever. This can happen as a result of monomorphizing a drop of a
// generic. In order to make sure that generic and non-generic code behaves
// roughly the same (and in keeping with Mir semantics) we do nothing here.
self.go_to_block(target);
return Ok(());
}
let place = self.eval_place(place)?;
trace!("TerminatorKind::drop: {:?}, type {}", place, ty);
self.drop_in_place(&place, instance, target, unwind)?;
}
Assert { ref cond, expected, ref msg, target, unwind } => {
let ignored =
M::ignore_optional_overflow_checks(self) && msg.is_optional_overflow_check();
let cond_val = self.read_scalar(&self.eval_operand(cond, None)?)?.to_bool()?;
if ignored || expected == cond_val {
self.go_to_block(target);
} else {
M::assert_panic(self, msg, unwind)?;
}
}
UnwindTerminate(reason) => {
M::unwind_terminate(self, reason)?;
}
// When we encounter Resume, we've finished unwinding
// cleanup for the current stack frame. We pop it in order
// to continue unwinding the next frame
UnwindResume => {
trace!("unwinding: resuming from cleanup");
// By definition, a Resume terminator means
// that we're unwinding
self.pop_stack_frame(/* unwinding */ true)?;
return Ok(());
}
// It is UB to ever encounter this.
Unreachable => throw_ub!(Unreachable),
// These should never occur for MIR we actually run.
FalseEdge { .. } | FalseUnwind { .. } | Yield { .. } | GeneratorDrop => span_bug!(
terminator.source_info.span,
"{:#?} should have been eliminated by MIR pass",
terminator.kind
),
InlineAsm { template, ref operands, options, destination, .. } => {
M::eval_inline_asm(self, template, operands, options)?;
if options.contains(InlineAsmOptions::NORETURN) {
throw_ub_custom!(fluent::const_eval_noreturn_asm_returned);
}
self.go_to_block(
destination
.expect("InlineAsm terminators without noreturn must have a destination"),
)
}
}
Ok(())
}
/// Evaluate the arguments of a function call
pub(super) fn eval_fn_call_arguments(
&self,
ops: &[mir::Operand<'tcx>],
) -> InterpResult<'tcx, Vec<FnArg<'tcx, M::Provenance>>> {
ops.iter()
.map(|op| {
Ok(match op {
mir::Operand::Move(place) => FnArg::InPlace(self.eval_place(*place)?),
_ => FnArg::Copy(self.eval_operand(op, None)?),
})
})
.collect()
}
/// Find the wrapped inner type of a transparent wrapper.
/// Must not be called on 1-ZST (as they don't have a uniquely defined "wrapped field").
///
/// We work with `TyAndLayout` here since that makes it much easier to iterate over all fields.
fn unfold_transparent(
&self,
layout: TyAndLayout<'tcx>,
may_unfold: impl Fn(AdtDef<'tcx>) -> bool,
) -> TyAndLayout<'tcx> {
match layout.ty.kind() {
ty::Adt(adt_def, _) if adt_def.repr().transparent() && may_unfold(*adt_def) => {
assert!(!adt_def.is_enum());
// Find the non-1-ZST field, and recurse.
let (_, field) = layout.non_1zst_field(self).unwrap();
self.unfold_transparent(field, may_unfold)
}
// Not a transparent type, no further unfolding.
_ => layout,
}
}
/// Unwrap types that are guaranteed a null-pointer-optimization
fn unfold_npo(&self, layout: TyAndLayout<'tcx>) -> InterpResult<'tcx, TyAndLayout<'tcx>> {
// Check if this is `Option` wrapping some type.
let inner = match layout.ty.kind() {
ty::Adt(def, args) if self.tcx.is_diagnostic_item(sym::Option, def.did()) => {
args[0].as_type().unwrap()
}
_ => {
// Not an `Option`.
return Ok(layout);
}
};
let inner = self.layout_of(inner)?;
// Check if the inner type is one of the NPO-guaranteed ones.
// For that we first unpeel transparent *structs* (but not unions).
let is_npo = |def: AdtDef<'tcx>| {
self.tcx.has_attr(def.did(), sym::rustc_nonnull_optimization_guaranteed)
};
let inner = self.unfold_transparent(inner, /* may_unfold */ |def| {
// Stop at NPO tpyes so that we don't miss that attribute in the check below!
def.is_struct() && !is_npo(def)
});
Ok(match inner.ty.kind() {
ty::Ref(..) | ty::FnPtr(..) => {
// Option<&T> behaves like &T, and same for fn()
inner
}
ty::Adt(def, _) if is_npo(*def) => {
// Once we found a `nonnull_optimization_guaranteed` type, further strip off
// newtype structs from it to find the underlying ABI type.
self.unfold_transparent(inner, /* may_unfold */ |def| def.is_struct())
}
_ => {
// Everything else we do not unfold.
layout
}
})
}
/// Check if these two layouts look like they are fn-ABI-compatible.
/// (We also compare the `PassMode`, so this doesn't have to check everything. But it turns out
/// that only checking the `PassMode` is insufficient.)
fn layout_compat(
&self,
caller: TyAndLayout<'tcx>,
callee: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, bool> {
// Fast path: equal types are definitely compatible.
if caller.ty == callee.ty {
return Ok(true);
}
// 1-ZST are compatible with all 1-ZST (and with nothing else).
if caller.is_1zst() || callee.is_1zst() {
return Ok(caller.is_1zst() && callee.is_1zst());
}
// Unfold newtypes and NPO optimizations.
let unfold = |layout: TyAndLayout<'tcx>| {
self.unfold_npo(self.unfold_transparent(layout, /* may_unfold */ |_def| true))
};
let caller = unfold(caller)?;
let callee = unfold(callee)?;
// Now see if these inner types are compatible.
// Compatible pointer types. For thin pointers, we have to accept even non-`repr(transparent)`
// things as compatible due to `DispatchFromDyn`. For instance, `Rc<i32>` and `*mut i32`
// must be compatible. So we just accept everything with Pointer ABI as compatible,
// even if this will accept some code that is not stably guaranteed to work.
// This also handles function pointers.
let thin_pointer = |layout: TyAndLayout<'tcx>| match layout.abi {
abi::Abi::Scalar(s) => match s.primitive() {
abi::Primitive::Pointer(addr_space) => Some(addr_space),
_ => None,
},
_ => None,
};
if let (Some(caller), Some(callee)) = (thin_pointer(caller), thin_pointer(callee)) {
return Ok(caller == callee);
}
// For wide pointers we have to get the pointee type.
let pointee_ty = |ty: Ty<'tcx>| -> InterpResult<'tcx, Option<Ty<'tcx>>> {
// We cannot use `builtin_deref` here since we need to reject `Box<T, MyAlloc>`.
Ok(Some(match ty.kind() {
ty::Ref(_, ty, _) => *ty,
ty::RawPtr(mt) => mt.ty,
// We should only accept `Box` with the default allocator.
// It's hard to test for that though so we accept every 1-ZST allocator.
ty::Adt(def, args)
if def.is_box()
&& self.layout_of(args[1].expect_ty()).is_ok_and(|l| l.is_1zst()) =>
{
args[0].expect_ty()
}
_ => return Ok(None),
}))
};
if let (Some(caller), Some(callee)) = (pointee_ty(caller.ty)?, pointee_ty(callee.ty)?) {
// This is okay if they have the same metadata type.
let meta_ty = |ty: Ty<'tcx>| {
let (meta, only_if_sized) = ty.ptr_metadata_ty(*self.tcx, |ty| ty);
assert!(
!only_if_sized,
"there should be no more 'maybe has that metadata' types during interpretation"
);
meta
};
return Ok(meta_ty(caller) == meta_ty(callee));
}
// Compatible integer types (in particular, usize vs ptr-sized-u32/u64).
let int_ty = |ty: Ty<'tcx>| {
Some(match ty.kind() {
ty::Int(ity) => (Integer::from_int_ty(&self.tcx, *ity), /* signed */ true),
ty::Uint(uty) => (Integer::from_uint_ty(&self.tcx, *uty), /* signed */ false),
_ => return None,
})
};
if let (Some(caller), Some(callee)) = (int_ty(caller.ty), int_ty(callee.ty)) {
// This is okay if they are the same integer type.
return Ok(caller == callee);
}
// Fall back to exact equality.
// FIXME: We are missing the rules for "repr(C) wrapping compatible types".
Ok(caller == callee)
}
fn check_argument_compat(
&self,
caller_abi: &ArgAbi<'tcx, Ty<'tcx>>,
callee_abi: &ArgAbi<'tcx, Ty<'tcx>>,
) -> InterpResult<'tcx, bool> {
// We do not want to accept things as ABI-compatible that just "happen to be" compatible on the current target,
// so we implement a type-based check that reflects the guaranteed rules for ABI compatibility.
if self.layout_compat(caller_abi.layout, callee_abi.layout)? {
// Ensure that our checks imply actual ABI compatibility for this concrete call.
assert!(caller_abi.eq_abi(&callee_abi));
return Ok(true);
} else {
trace!(
"check_argument_compat: incompatible ABIs:\ncaller: {:?}\ncallee: {:?}",
caller_abi,
callee_abi
);
return Ok(false);
}
}
/// Initialize a single callee argument, checking the types for compatibility.
fn pass_argument<'x, 'y>(
&mut self,
caller_args: &mut impl Iterator<
Item = (&'x FnArg<'tcx, M::Provenance>, &'y ArgAbi<'tcx, Ty<'tcx>>),
>,
callee_abi: &ArgAbi<'tcx, Ty<'tcx>>,
callee_arg: &mir::Place<'tcx>,
callee_ty: Ty<'tcx>,
already_live: bool,
) -> InterpResult<'tcx>
where
'tcx: 'x,
'tcx: 'y,
{
assert_eq!(callee_ty, callee_abi.layout.ty);
if matches!(callee_abi.mode, PassMode::Ignore) {
// This one is skipped. Still must be made live though!
if !already_live {
self.storage_live(callee_arg.as_local().unwrap())?;
}
return Ok(());
}
// Find next caller arg.
let Some((caller_arg, caller_abi)) = caller_args.next() else {
throw_ub_custom!(fluent::const_eval_not_enough_caller_args);
};
assert_eq!(caller_arg.layout().layout, caller_abi.layout.layout);
// Sadly we cannot assert that `caller_arg.layout().ty` and `caller_abi.layout.ty` are
// equal; in closures the types sometimes differ. We just hope that `caller_abi` is the
// right type to print to the user.
// Check compatibility
if !self.check_argument_compat(caller_abi, callee_abi)? {
throw_ub!(AbiMismatchArgument {
caller_ty: caller_abi.layout.ty,
callee_ty: callee_abi.layout.ty
});
}
// We work with a copy of the argument for now; if this is in-place argument passing, we
// will later protect the source it comes from. This means the callee cannot observe if we
// did in-place of by-copy argument passing, except for pointer equality tests.
let caller_arg_copy = self.copy_fn_arg(&caller_arg)?;
if !already_live {
let local = callee_arg.as_local().unwrap();
let meta = caller_arg_copy.meta();
// `check_argument_compat` ensures that if metadata is needed, both have the same type,
// so we know they will use the metadata the same way.
assert!(!meta.has_meta() || caller_arg_copy.layout.ty == callee_ty);
self.storage_live_dyn(local, meta)?;
}
// Now we can finally actually evaluate the callee place.
let callee_arg = self.eval_place(*callee_arg)?;
// We allow some transmutes here.
// FIXME: Depending on the PassMode, this should reset some padding to uninitialized. (This
// is true for all `copy_op`, but there are a lot of special cases for argument passing
// specifically.)
self.copy_op(&caller_arg_copy, &callee_arg, /*allow_transmute*/ true)?;
// If this was an in-place pass, protect the place it comes from for the duration of the call.
if let FnArg::InPlace(place) = caller_arg {
M::protect_in_place_function_argument(self, place)?;
}
Ok(())
}
/// Call this function -- pushing the stack frame and initializing the arguments.
///
/// `caller_fn_abi` is used to determine if all the arguments are passed the proper way.
/// However, we also need `caller_abi` to determine if we need to do untupling of arguments.
///
/// `with_caller_location` indicates whether the caller passed a caller location. Miri
/// implements caller locations without argument passing, but to match `FnAbi` we need to know
/// when those arguments are present.
pub(crate) fn eval_fn_call(
&mut self,
fn_val: FnVal<'tcx, M::ExtraFnVal>,
(caller_abi, caller_fn_abi): (Abi, &FnAbi<'tcx, Ty<'tcx>>),
args: &[FnArg<'tcx, M::Provenance>],
with_caller_location: bool,
destination: &PlaceTy<'tcx, M::Provenance>,
target: Option<mir::BasicBlock>,
mut unwind: mir::UnwindAction,
) -> InterpResult<'tcx> {
trace!("eval_fn_call: {:#?}", fn_val);
let instance = match fn_val {
FnVal::Instance(instance) => instance,
FnVal::Other(extra) => {
return M::call_extra_fn(
self,
extra,
caller_abi,
args,
destination,
target,
unwind,
);
}
};
match instance.def {
ty::InstanceDef::Intrinsic(def_id) => {
assert!(self.tcx.is_intrinsic(def_id));
// FIXME: Should `InPlace` arguments be reset to uninit?
M::call_intrinsic(
self,
instance,
&self.copy_fn_args(args)?,
destination,
target,
unwind,
)
}
ty::InstanceDef::VTableShim(..)
| ty::InstanceDef::ReifyShim(..)
| ty::InstanceDef::ClosureOnceShim { .. }
| ty::InstanceDef::FnPtrShim(..)
| ty::InstanceDef::DropGlue(..)
| ty::InstanceDef::CloneShim(..)
| ty::InstanceDef::FnPtrAddrShim(..)
| ty::InstanceDef::ThreadLocalShim(..)
| ty::InstanceDef::Item(_) => {
// We need MIR for this fn
let Some((body, instance)) = M::find_mir_or_eval_fn(
self,
instance,
caller_abi,
args,
destination,
target,
unwind,
)?
else {
return Ok(());
};
// Compute callee information using the `instance` returned by
// `find_mir_or_eval_fn`.
// FIXME: for variadic support, do we have to somehow determine callee's extra_args?
let callee_fn_abi = self.fn_abi_of_instance(instance, ty::List::empty())?;
if callee_fn_abi.c_variadic || caller_fn_abi.c_variadic {
throw_unsup_format!("calling a c-variadic function is not supported");
}
if M::enforce_abi(self) {
if caller_fn_abi.conv != callee_fn_abi.conv {
throw_ub_custom!(
fluent::const_eval_incompatible_calling_conventions,
callee_conv = format!("{:?}", callee_fn_abi.conv),
caller_conv = format!("{:?}", caller_fn_abi.conv),
)
}
}
// Check that all target features required by the callee (i.e., from
// the attribute `#[target_feature(enable = ...)]`) are enabled at
// compile time.
self.check_fn_target_features(instance)?;
if !callee_fn_abi.can_unwind {
// The callee cannot unwind, so force the `Unreachable` unwind handling.
unwind = mir::UnwindAction::Unreachable;
}
self.push_stack_frame(
instance,
body,
destination,
StackPopCleanup::Goto { ret: target, unwind },
)?;
// If an error is raised here, pop the frame again to get an accurate backtrace.
// To this end, we wrap it all in a `try` block.
let res: InterpResult<'tcx> = try {
trace!(
"caller ABI: {:?}, args: {:#?}",
caller_abi,
args.iter()
.map(|arg| (
arg.layout().ty,
match arg {
FnArg::Copy(op) => format!("copy({:?})", *op),
FnArg::InPlace(place) => format!("in-place({:?})", *place),
}
))
.collect::<Vec<_>>()
);
trace!(
"spread_arg: {:?}, locals: {:#?}",
body.spread_arg,
body.args_iter()
.map(|local| (
local,
self.layout_of_local(self.frame(), local, None).unwrap().ty
))
.collect::<Vec<_>>()
);
// In principle, we have two iterators: Where the arguments come from, and where
// they go to.
// For where they come from: If the ABI is RustCall, we untuple the
// last incoming argument. These two iterators do not have the same type,
// so to keep the code paths uniform we accept an allocation
// (for RustCall ABI only).
let caller_args: Cow<'_, [FnArg<'tcx, M::Provenance>]> =
if caller_abi == Abi::RustCall && !args.is_empty() {
// Untuple
let (untuple_arg, args) = args.split_last().unwrap();
trace!("eval_fn_call: Will pass last argument by untupling");
Cow::from(
args.iter()
.map(|a| Ok(a.clone()))
.chain(
(0..untuple_arg.layout().fields.count())
.map(|i| self.fn_arg_field(untuple_arg, i)),
)
.collect::<InterpResult<'_, Vec<_>>>()?,
)
} else {
// Plain arg passing
Cow::from(args)
};
// If `with_caller_location` is set we pretend there is an extra argument (that
// we will not pass).
assert_eq!(
caller_args.len() + if with_caller_location { 1 } else { 0 },
caller_fn_abi.args.len(),
"mismatch between caller ABI and caller arguments",
);
let mut caller_args = caller_args
.iter()
.zip(caller_fn_abi.args.iter())
.filter(|arg_and_abi| !matches!(arg_and_abi.1.mode, PassMode::Ignore));
// Now we have to spread them out across the callee's locals,
// taking into account the `spread_arg`. If we could write
// this is a single iterator (that handles `spread_arg`), then
// `pass_argument` would be the loop body. It takes care to
// not advance `caller_iter` for ignored arguments.
let mut callee_args_abis = callee_fn_abi.args.iter();
for local in body.args_iter() {
// Construct the destination place for this argument. At this point all
// locals are still dead, so we cannot construct a `PlaceTy`.
let dest = mir::Place::from(local);
// `layout_of_local` does more than just the substitution we need to get the
// type, but the result gets cached so this avoids calling the substitution
// query *again* the next time this local is accessed.
let ty = self.layout_of_local(self.frame(), local, None)?.ty;
if Some(local) == body.spread_arg {
// Make the local live once, then fill in the value field by field.
self.storage_live(local)?;
// Must be a tuple
let ty::Tuple(fields) = ty.kind() else {
span_bug!(self.cur_span(), "non-tuple type for `spread_arg`: {ty}")
};
for (i, field_ty) in fields.iter().enumerate() {
let dest = dest.project_deeper(
&[mir::ProjectionElem::Field(
FieldIdx::from_usize(i),
field_ty,
)],
*self.tcx,
);
let callee_abi = callee_args_abis.next().unwrap();
self.pass_argument(
&mut caller_args,
callee_abi,
&dest,
field_ty,
/* already_live */ true,
)?;
}
} else {
// Normal argument. Cannot mark it as live yet, it might be unsized!
let callee_abi = callee_args_abis.next().unwrap();
self.pass_argument(
&mut caller_args,
callee_abi,
&dest,
ty,
/* already_live */ false,
)?;
}
}
// If the callee needs a caller location, pretend we consume one more argument from the ABI.
if instance.def.requires_caller_location(*self.tcx) {
callee_args_abis.next().unwrap();
}
// Now we should have no more caller args or callee arg ABIs
assert!(
callee_args_abis.next().is_none(),
"mismatch between callee ABI and callee body arguments"
);
if caller_args.next().is_some() {
throw_ub_custom!(fluent::const_eval_too_many_caller_args);
}
// Don't forget to check the return type!
if !self.check_argument_compat(&caller_fn_abi.ret, &callee_fn_abi.ret)? {
throw_ub!(AbiMismatchReturn {
caller_ty: caller_fn_abi.ret.layout.ty,
callee_ty: callee_fn_abi.ret.layout.ty
});
}
// Ensure the return place is aligned and dereferenceable, and protect it for
// in-place return value passing.
if let Either::Left(mplace) = destination.as_mplace_or_local() {
self.check_mplace(&mplace)?;
} else {
// Nothing to do for locals, they are always properly allocated and aligned.
}
M::protect_in_place_function_argument(self, destination)?;
// Don't forget to mark "initially live" locals as live.
self.storage_live_for_always_live_locals()?;
};
match res {
Err(err) => {
self.stack_mut().pop();
Err(err)
}
Ok(()) => Ok(()),
}
}
// `InstanceDef::Virtual` does not have callable MIR. Calls to `Virtual` instances must be
// codegen'd / interpreted as virtual calls through the vtable.
ty::InstanceDef::Virtual(def_id, idx) => {
let mut args = args.to_vec();
// We have to implement all "object safe receivers". So we have to go search for a
// pointer or `dyn Trait` type, but it could be wrapped in newtypes. So recursively
// unwrap those newtypes until we are there.
// An `InPlace` does nothing here, we keep the original receiver intact. We can't
// really pass the argument in-place anyway, and we are constructing a new
// `Immediate` receiver.
let mut receiver = self.copy_fn_arg(&args[0])?;
let receiver_place = loop {
match receiver.layout.ty.kind() {
ty::Ref(..) | ty::RawPtr(..) => {
// We do *not* use `deref_pointer` here: we don't want to conceptually
// create a place that must be dereferenceable, since the receiver might
// be a raw pointer and (for `*const dyn Trait`) we don't need to
// actually access memory to resolve this method.
// Also see <https://github.com/rust-lang/miri/issues/2786>.
let val = self.read_immediate(&receiver)?;
break self.ref_to_mplace(&val)?;
}
ty::Dynamic(.., ty::Dyn) => break receiver.assert_mem_place(), // no immediate unsized values
ty::Dynamic(.., ty::DynStar) => {
// Not clear how to handle this, so far we assume the receiver is always a pointer.
span_bug!(
self.cur_span(),
"by-value calls on a `dyn*`... are those a thing?"
);
}
_ => {
// Not there yet, search for the only non-ZST field.
// (The rules for `DispatchFromDyn` ensure there's exactly one such field.)
let (idx, _) = receiver.layout.non_1zst_field(self).expect(
"not exactly one non-1-ZST field in a `DispatchFromDyn` type",
);
receiver = self.project_field(&receiver, idx)?;
}
}
};
// Obtain the underlying trait we are working on, and the adjusted receiver argument.
let (vptr, dyn_ty, adjusted_receiver) = if let ty::Dynamic(data, _, ty::DynStar) =
receiver_place.layout.ty.kind()
{
let (recv, vptr) = self.unpack_dyn_star(&receiver_place)?;
let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
if dyn_trait != data.principal() {
throw_ub_custom!(fluent::const_eval_dyn_star_call_vtable_mismatch);
}
(vptr, dyn_ty, recv.ptr())
} else {
// Doesn't have to be a `dyn Trait`, but the unsized tail must be `dyn Trait`.
// (For that reason we also cannot use `unpack_dyn_trait`.)
let receiver_tail = self
.tcx
.struct_tail_erasing_lifetimes(receiver_place.layout.ty, self.param_env);
let ty::Dynamic(data, _, ty::Dyn) = receiver_tail.kind() else {
span_bug!(
self.cur_span(),
"dynamic call on non-`dyn` type {}",
receiver_tail
)
};
assert!(receiver_place.layout.is_unsized());
// Get the required information from the vtable.
let vptr = receiver_place.meta().unwrap_meta().to_pointer(self)?;
let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
if dyn_trait != data.principal() {
throw_ub_custom!(fluent::const_eval_dyn_call_vtable_mismatch);
}
// It might be surprising that we use a pointer as the receiver even if this
// is a by-val case; this works because by-val passing of an unsized `dyn
// Trait` to a function is actually desugared to a pointer.
(vptr, dyn_ty, receiver_place.ptr())
};
// Now determine the actual method to call. We can do that in two different ways and
// compare them to ensure everything fits.
let Some(ty::VtblEntry::Method(fn_inst)) =
self.get_vtable_entries(vptr)?.get(idx).copied()
else {
// FIXME(fee1-dead) these could be variants of the UB info enum instead of this
throw_ub_custom!(fluent::const_eval_dyn_call_not_a_method);
};
trace!("Virtual call dispatches to {fn_inst:#?}");
if cfg!(debug_assertions) {
let tcx = *self.tcx;
let trait_def_id = tcx.trait_of_item(def_id).unwrap();
let virtual_trait_ref =
ty::TraitRef::from_method(tcx, trait_def_id, instance.args);
let existential_trait_ref =
ty::ExistentialTraitRef::erase_self_ty(tcx, virtual_trait_ref);
let concrete_trait_ref = existential_trait_ref.with_self_ty(tcx, dyn_ty);
let concrete_method = Instance::resolve_for_vtable(
tcx,
self.param_env,
def_id,
instance.args.rebase_onto(tcx, trait_def_id, concrete_trait_ref.args),
)
.unwrap();
assert_eq!(fn_inst, concrete_method);
}
// Adjust receiver argument. Layout can be any (thin) ptr.
let receiver_ty = Ty::new_mut_ptr(self.tcx.tcx, dyn_ty);
args[0] = FnArg::Copy(
ImmTy::from_immediate(
Scalar::from_maybe_pointer(adjusted_receiver, self).into(),
self.layout_of(receiver_ty)?,
)
.into(),
);
trace!("Patched receiver operand to {:#?}", args[0]);
// Need to also adjust the type in the ABI. Strangely, the layout there is actually
// already fine! Just the type is bogus. This is due to what `force_thin_self_ptr`
// does in `fn_abi_new_uncached`; supposedly, codegen relies on having the bogus
// type, so we just patch this up locally.
let mut caller_fn_abi = caller_fn_abi.clone();
caller_fn_abi.args[0].layout.ty = receiver_ty;
// recurse with concrete function
self.eval_fn_call(
FnVal::Instance(fn_inst),
(caller_abi, &caller_fn_abi),
&args,
with_caller_location,
destination,
target,
unwind,
)
}
}
}
fn check_fn_target_features(&self, instance: ty::Instance<'tcx>) -> InterpResult<'tcx, ()> {
let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
if attrs
.target_features
.iter()
.any(|feature| !self.tcx.sess.target_features.contains(feature))
{
throw_ub_custom!(
fluent::const_eval_unavailable_target_features_for_fn,
unavailable_feats = attrs
.target_features
.iter()
.filter(|&feature| !self.tcx.sess.target_features.contains(feature))
.fold(String::new(), |mut s, feature| {
if !s.is_empty() {
s.push_str(", ");
}
s.push_str(feature.as_str());
s
}),
);
}
Ok(())
}
fn drop_in_place(
&mut self,
place: &PlaceTy<'tcx, M::Provenance>,
instance: ty::Instance<'tcx>,
target: mir::BasicBlock,
unwind: mir::UnwindAction,
) -> InterpResult<'tcx> {
trace!("drop_in_place: {:?},\n instance={:?}", place, instance);
// We take the address of the object. This may well be unaligned, which is fine
// for us here. However, unaligned accesses will probably make the actual drop
// implementation fail -- a problem shared by rustc.
let place = self.force_allocation(place)?;
let place = match place.layout.ty.kind() {
ty::Dynamic(_, _, ty::Dyn) => {
// Dropping a trait object. Need to find actual drop fn.
self.unpack_dyn_trait(&place)?.0
}
ty::Dynamic(_, _, ty::DynStar) => {
// Dropping a `dyn*`. Need to find actual drop fn.
self.unpack_dyn_star(&place)?.0
}
_ => {
debug_assert_eq!(
instance,
ty::Instance::resolve_drop_in_place(*self.tcx, place.layout.ty)
);
place
}
};
let instance = ty::Instance::resolve_drop_in_place(*self.tcx, place.layout.ty);
let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty())?;
let arg = self.mplace_to_ref(&place)?;
let ret = MPlaceTy::fake_alloc_zst(self.layout_of(self.tcx.types.unit)?);
self.eval_fn_call(
FnVal::Instance(instance),
(Abi::Rust, fn_abi),
&[FnArg::Copy(arg.into())],
false,
&ret.into(),
Some(target),
unwind,
)
}
}