blob: 57e40e168fa48e0b281541ee9beaef7ce7293f95 [file] [log] [blame]
use std::borrow::Cow;
use rustc_ast::ast::InlineAsmOptions;
use rustc_middle::ty::layout::{FnAbiOf, LayoutOf};
use rustc_middle::ty::Instance;
use rustc_middle::{
mir,
ty::{self, Ty},
};
use rustc_target::abi;
use rustc_target::abi::call::{ArgAbi, ArgAttribute, ArgAttributes, FnAbi, PassMode};
use rustc_target::spec::abi::Abi;
use super::{
FnVal, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemoryKind, OpTy, Operand,
PlaceTy, Scalar, StackPopCleanup, StackPopUnwind,
};
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
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, switch_ty } => {
let discr = self.read_immediate(&self.eval_operand(discr, None)?)?;
trace!("SwitchInt({:?})", *discr);
assert_eq!(discr.layout.ty, switch_ty);
// 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
.overflowing_binary_op(
mir::BinOp::Eq,
&discr,
&ImmTy::from_uint(const_int, discr.layout),
)?
.0;
if res.to_bool()? {
target_block = target;
break;
}
}
self.go_to_block(target_block);
}
Call {
ref func,
ref args,
destination,
target,
ref cleanup,
from_hir_call: _,
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_operands(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(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, substs) => {
let instance =
self.resolve(ty::WithOptConstParam::unknown(def_id), substs)?;
(
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,
match (cleanup, fn_abi.can_unwind) {
(Some(cleanup), true) => StackPopUnwind::Cleanup(*cleanup),
(None, true) => StackPopUnwind::Skip,
(_, false) => StackPopUnwind::NotAllowed,
},
)?;
// 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 } => {
let place = self.eval_place(place)?;
let ty = place.layout.ty;
trace!("TerminatorKind::drop: {:?}, type {}", place, ty);
let instance = Instance::resolve_drop_in_place(*self.tcx, ty);
self.drop_in_place(&place, instance, target, unwind)?;
}
Assert { ref cond, expected, ref msg, target, cleanup } => {
let cond_val = self.read_scalar(&self.eval_operand(cond, None)?)?.to_bool()?;
if expected == cond_val {
self.go_to_block(target);
} else {
M::assert_panic(self, msg, cleanup)?;
}
}
Abort => {
M::abort(self, "the program aborted execution".to_owned())?;
}
// 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
Resume => {
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.
DropAndReplace { .. }
| 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_format!("returned from noreturn inline assembly");
}
self.go_to_block(
destination
.expect("InlineAsm terminators without noreturn must have a destination"),
)
}
}
Ok(())
}
fn check_argument_compat(
caller_abi: &ArgAbi<'tcx, Ty<'tcx>>,
callee_abi: &ArgAbi<'tcx, Ty<'tcx>>,
) -> bool {
// Heuristic for type comparison.
let layout_compat = || {
if caller_abi.layout.ty == callee_abi.layout.ty {
// No question
return true;
}
if caller_abi.layout.is_unsized() || callee_abi.layout.is_unsized() {
// No, no, no. We require the types to *exactly* match for unsized arguments. If
// these are somehow unsized "in a different way" (say, `dyn Trait` vs `[i32]`),
// then who knows what happens.
return false;
}
if caller_abi.layout.size != callee_abi.layout.size
|| caller_abi.layout.align.abi != callee_abi.layout.align.abi
{
// This cannot go well...
return false;
}
// The rest *should* be okay, but we are extra conservative.
match (caller_abi.layout.abi, callee_abi.layout.abi) {
// Different valid ranges are okay (once we enforce validity,
// that will take care to make it UB to leave the range, just
// like for transmute).
(abi::Abi::Scalar(caller), abi::Abi::Scalar(callee)) => {
caller.primitive() == callee.primitive()
}
(
abi::Abi::ScalarPair(caller1, caller2),
abi::Abi::ScalarPair(callee1, callee2),
) => {
caller1.primitive() == callee1.primitive()
&& caller2.primitive() == callee2.primitive()
}
// Be conservative
_ => false,
}
};
// When comparing the PassMode, we have to be smart about comparing the attributes.
let arg_attr_compat = |a1: &ArgAttributes, a2: &ArgAttributes| {
// There's only one regular attribute that matters for the call ABI: InReg.
// Everything else is things like noalias, dereferenceable, nonnull, ...
// (This also applies to pointee_size, pointee_align.)
if a1.regular.contains(ArgAttribute::InReg) != a2.regular.contains(ArgAttribute::InReg)
{
return false;
}
// We also compare the sign extension mode -- this could let the callee make assumptions
// about bits that conceptually were not even passed.
if a1.arg_ext != a2.arg_ext {
return false;
}
return true;
};
let mode_compat = || match (&caller_abi.mode, &callee_abi.mode) {
(PassMode::Ignore, PassMode::Ignore) => true,
(PassMode::Direct(a1), PassMode::Direct(a2)) => arg_attr_compat(a1, a2),
(PassMode::Pair(a1, b1), PassMode::Pair(a2, b2)) => {
arg_attr_compat(a1, a2) && arg_attr_compat(b1, b2)
}
(PassMode::Cast(c1, pad1), PassMode::Cast(c2, pad2)) => c1 == c2 && pad1 == pad2,
(
PassMode::Indirect { attrs: a1, extra_attrs: None, on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: None, on_stack: s2 },
) => arg_attr_compat(a1, a2) && s1 == s2,
(
PassMode::Indirect { attrs: a1, extra_attrs: Some(e1), on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: Some(e2), on_stack: s2 },
) => arg_attr_compat(a1, a2) && arg_attr_compat(e1, e2) && s1 == s2,
_ => false,
};
if layout_compat() && mode_compat() {
return true;
}
trace!(
"check_argument_compat: incompatible ABIs:\ncaller: {:?}\ncallee: {:?}",
caller_abi,
callee_abi
);
return 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 OpTy<'tcx, M::Provenance>, &'y ArgAbi<'tcx, Ty<'tcx>>),
>,
callee_abi: &ArgAbi<'tcx, Ty<'tcx>>,
callee_arg: &PlaceTy<'tcx, M::Provenance>,
) -> InterpResult<'tcx>
where
'tcx: 'x,
'tcx: 'y,
{
if matches!(callee_abi.mode, PassMode::Ignore) {
// This one is skipped.
return Ok(());
}
// Find next caller arg.
let (caller_arg, caller_abi) = caller_args.next().ok_or_else(|| {
err_ub_format!("calling a function with fewer arguments than it requires")
})?;
// Now, check
if !Self::check_argument_compat(caller_abi, callee_abi) {
throw_ub_format!(
"calling a function with argument of type {:?} passing data of type {:?}",
callee_arg.layout.ty,
caller_arg.layout.ty
)
}
// Special handling for unsized parameters.
if caller_arg.layout.is_unsized() {
// `check_argument_compat` ensures that both have the same type, so we know they will use the metadata the same way.
assert_eq!(caller_arg.layout.ty, callee_arg.layout.ty);
// We have to properly pre-allocate the memory for the callee.
// So let's tear down some wrappers.
// This all has to be in memory, there are no immediate unsized values.
let src = caller_arg.assert_mem_place();
// The destination cannot be one of these "spread args".
let (dest_frame, dest_local) = callee_arg.assert_local();
// We are just initializing things, so there can't be anything here yet.
assert!(matches!(
*self.local_to_op(&self.stack()[dest_frame], dest_local, None)?,
Operand::Immediate(Immediate::Uninit)
));
// Allocate enough memory to hold `src`.
let Some((size, align)) = self.size_and_align_of_mplace(&src)? else {
span_bug!(self.cur_span(), "unsized fn arg with `extern` type tail should not be allowed")
};
let ptr = self.allocate_ptr(size, align, MemoryKind::Stack)?;
let dest_place =
MPlaceTy::from_aligned_ptr_with_meta(ptr.into(), callee_arg.layout, src.meta);
// Update the local to be that new place.
*M::access_local_mut(self, dest_frame, dest_local)? = Operand::Indirect(*dest_place);
}
// 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, callee_arg, /*allow_transmute*/ true)
}
/// 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: &[OpTy<'tcx, M::Provenance>],
with_caller_location: bool,
destination: &PlaceTy<'tcx, M::Provenance>,
target: Option<mir::BasicBlock>,
mut unwind: StackPopUnwind,
) -> 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));
// caller_fn_abi is not relevant here, we interpret the arguments directly for each intrinsic.
M::call_intrinsic(self, instance, args, destination, target, unwind)
}
ty::InstanceDef::VTableShim(..)
| ty::InstanceDef::ReifyShim(..)
| ty::InstanceDef::ClosureOnceShim { .. }
| ty::InstanceDef::FnPtrShim(..)
| ty::InstanceDef::DropGlue(..)
| ty::InstanceDef::CloneShim(..)
| 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_format!(
"calling a function with calling convention {:?} using calling convention {:?}",
callee_fn_abi.conv,
caller_fn_abi.conv
)
}
}
if !matches!(unwind, StackPopUnwind::NotAllowed) && !callee_fn_abi.can_unwind {
// The callee cannot unwind.
unwind = StackPopUnwind::NotAllowed;
}
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, format!("{:?}", **arg)))
.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<'_, [OpTy<'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.operand_field(untuple_arg, i)),
)
.collect::<InterpResult<'_, Vec<OpTy<'tcx, M::Provenance>>>>(
)?,
)
} 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 ZSTs.
let mut callee_args_abis = callee_fn_abi.args.iter();
for local in body.args_iter() {
let dest = self.eval_place(mir::Place::from(local))?;
if Some(local) == body.spread_arg {
// Must be a tuple
for i in 0..dest.layout.fields.count() {
let dest = self.place_field(&dest, i)?;
let callee_abi = callee_args_abis.next().unwrap();
self.pass_argument(&mut caller_args, callee_abi, &dest)?;
}
} else {
// Normal argument
let callee_abi = callee_args_abis.next().unwrap();
self.pass_argument(&mut caller_args, callee_abi, &dest)?;
}
}
// 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_format!("calling a function with more arguments than it expected")
}
// Don't forget to check the return type!
if !Self::check_argument_compat(&caller_fn_abi.ret, &callee_fn_abi.ret) {
throw_ub_format!(
"calling a function with return type {:?} passing \
return place of type {:?}",
callee_fn_abi.ret.layout.ty,
caller_fn_abi.ret.layout.ty,
)
}
};
match res {
Err(err) => {
self.stack_mut().pop();
Err(err)
}
Ok(()) => Ok(()),
}
}
// cannot use the shim here, because that will only result in infinite recursion
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.
let mut receiver = args[0].clone();
let receiver_place = loop {
match receiver.layout.ty.kind() {
ty::Ref(..) | ty::RawPtr(..) => break self.deref_operand(&receiver)?,
ty::Dynamic(..) => break receiver.assert_mem_place(), // no immediate unsized values
_ => {
// Not there yet, search for the only non-ZST field.
let mut non_zst_field = None;
for i in 0..receiver.layout.fields.count() {
let field = self.operand_field(&receiver, i)?;
let zst =
field.layout.is_zst() && field.layout.align.abi.bytes() == 1;
if !zst {
assert!(
non_zst_field.is_none(),
"multiple non-ZST fields in dyn receiver type {}",
receiver.layout.ty
);
non_zst_field = Some(field);
}
}
receiver = non_zst_field.unwrap_or_else(|| {
panic!(
"no non-ZST fields in dyn receiver type {}",
receiver.layout.ty
)
});
}
}
};
// Obtain the underlying trait we are working on.
let receiver_tail = self
.tcx
.struct_tail_erasing_lifetimes(receiver_place.layout.ty, self.param_env);
let ty::Dynamic(data, ..) = receiver_tail.kind() else {
span_bug!(self.cur_span(), "dynamic call on non-`dyn` type {}", receiver_tail)
};
// 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_format!(
"`dyn` call on a pointer whose vtable does not match its type"
);
}
// 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 {
throw_ub_format!("`dyn` call trying to call something that is not a method")
};
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.substs);
assert_eq!(
receiver_tail,
virtual_trait_ref.self_ty(),
"mismatch in underlying dyn trait computation within Miri and MIR building",
);
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.substs.rebase_onto(tcx, trait_def_id, concrete_trait_ref.substs),
)
.unwrap();
assert_eq!(fn_inst, concrete_method);
}
// `*mut receiver_place.layout.ty` is almost the layout that we
// want for args[0]: We have to project to field 0 because we want
// a thin pointer.
assert!(receiver_place.layout.is_unsized());
let receiver_ptr_ty = self.tcx.mk_mut_ptr(receiver_place.layout.ty);
let this_receiver_ptr = self.layout_of(receiver_ptr_ty)?.field(self, 0);
// Adjust receiver argument.
args[0] = OpTy::from(ImmTy::from_immediate(
Scalar::from_maybe_pointer(receiver_place.ptr, self).into(),
this_receiver_ptr,
));
trace!("Patched receiver operand to {:#?}", args[0]);
// 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 drop_in_place(
&mut self,
place: &PlaceTy<'tcx, M::Provenance>,
instance: ty::Instance<'tcx>,
target: mir::BasicBlock,
unwind: Option<mir::BasicBlock>,
) -> InterpResult<'tcx> {
trace!("drop_in_place: {:?},\n {:?}, {:?}", *place, place.layout.ty, 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 (instance, place) = match place.layout.ty.kind() {
ty::Dynamic(..) => {
// Dropping a trait object. Need to find actual drop fn.
let place = self.unpack_dyn_trait(&place)?;
let instance = ty::Instance::resolve_drop_in_place(*self.tcx, place.layout.ty);
(instance, place)
}
_ => (instance, place),
};
let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty())?;
let arg = ImmTy::from_immediate(
place.to_ref(self),
self.layout_of(self.tcx.mk_mut_ptr(place.layout.ty))?,
);
let ret = MPlaceTy::fake_alloc_zst(self.layout_of(self.tcx.types.unit)?);
self.eval_fn_call(
FnVal::Instance(instance),
(Abi::Rust, fn_abi),
&[arg.into()],
false,
&ret.into(),
Some(target),
match unwind {
Some(cleanup) => StackPopUnwind::Cleanup(cleanup),
None => StackPopUnwind::Skip,
},
)
}
}