| //! Manages calling a concrete function (with known MIR body) with argument passing, |
| //! and returning the return value to the caller. |
| use std::assert_matches::assert_matches; |
| use std::borrow::Cow; |
| |
| use either::{Left, Right}; |
| use rustc_middle::ty::layout::{FnAbiOf, IntegerExt, LayoutOf, TyAndLayout}; |
| use rustc_middle::ty::{self, AdtDef, Instance, Ty}; |
| use rustc_middle::{bug, mir, span_bug}; |
| use rustc_span::sym; |
| use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode}; |
| use rustc_target::abi::{self, FieldIdx, Integer}; |
| use rustc_target::spec::abi::Abi; |
| use tracing::{info, instrument, trace}; |
| |
| use super::{ |
| CtfeProvenance, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy, |
| Projectable, Provenance, ReturnAction, Scalar, StackPopCleanup, StackPopInfo, interp_ok, |
| throw_ub, throw_ub_custom, throw_unsup_format, |
| }; |
| use crate::fluent_generated as fluent; |
| |
| /// An argument passed to a function. |
| #[derive(Clone, Debug)] |
| pub enum FnArg<'tcx, Prov: Provenance = CtfeProvenance> { |
| /// 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(MPlaceTy<'tcx, Prov>), |
| } |
| |
| impl<'tcx, Prov: Provenance> FnArg<'tcx, Prov> { |
| pub fn layout(&self) -> &TyAndLayout<'tcx> { |
| match self { |
| FnArg::Copy(op) => &op.layout, |
| FnArg::InPlace(mplace) => &mplace.layout, |
| } |
| } |
| } |
| |
| impl<'tcx, M: Machine<'tcx>> InterpCx<'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>) -> OpTy<'tcx, M::Provenance> { |
| match arg { |
| FnArg::Copy(op) => op.clone(), |
| FnArg::InPlace(mplace) => mplace.clone().into(), |
| } |
| } |
| |
| /// 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>], |
| ) -> Vec<OpTy<'tcx, M::Provenance>> { |
| args.iter().map(|fn_arg| self.copy_fn_arg(fn_arg)).collect() |
| } |
| |
| /// Helper function for argument untupling. |
| pub(super) fn fn_arg_field( |
| &self, |
| arg: &FnArg<'tcx, M::Provenance>, |
| field: usize, |
| ) -> InterpResult<'tcx, FnArg<'tcx, M::Provenance>> { |
| interp_ok(match arg { |
| FnArg::Copy(op) => FnArg::Copy(self.project_field(op, field)?), |
| FnArg::InPlace(mplace) => FnArg::InPlace(self.project_field(mplace, field)?), |
| }) |
| } |
| |
| /// 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 or if this is `Result` wrapping a 1-ZST and |
| // another type. |
| let ty::Adt(def, args) = layout.ty.kind() else { |
| // Not an ADT, so definitely no NPO. |
| return interp_ok(layout); |
| }; |
| let inner = if self.tcx.is_diagnostic_item(sym::Option, def.did()) { |
| // The wrapped type is the only arg. |
| self.layout_of(args[0].as_type().unwrap())? |
| } else if self.tcx.is_diagnostic_item(sym::Result, def.did()) { |
| // We want to extract which (if any) of the args is not a 1-ZST. |
| let lhs = self.layout_of(args[0].as_type().unwrap())?; |
| let rhs = self.layout_of(args[1].as_type().unwrap())?; |
| if lhs.is_1zst() { |
| rhs |
| } else if rhs.is_1zst() { |
| lhs |
| } else { |
| return interp_ok(layout); // no NPO |
| } |
| } else { |
| return interp_ok(layout); // no NPO |
| }; |
| |
| // 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 types so that we don't miss that attribute in the check below! |
| def.is_struct() && !is_npo(def) |
| }); |
| interp_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 interp_ok(true); |
| } |
| // 1-ZST are compatible with all 1-ZST (and with nothing else). |
| if caller.is_1zst() || callee.is_1zst() { |
| return interp_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 interp_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>`. |
| interp_ok(Some(match ty.kind() { |
| ty::Ref(_, ty, _) => *ty, |
| ty::RawPtr(ty, _) => *ty, |
| // We only accept `Box` with the default allocator. |
| _ if ty.is_box_global(*self.tcx) => ty.expect_boxed_ty(), |
| _ => return interp_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>| { |
| // Even if `ty` is normalized, the search for the unsized tail will project |
| // to fields, which can yield non-normalized types. So we need to provide a |
| // normalization function. |
| let normalize = |ty| self.tcx.normalize_erasing_regions(self.param_env, ty); |
| ty.ptr_metadata_ty(*self.tcx, normalize) |
| }; |
| return interp_ok(meta_ty(caller) == meta_ty(callee)); |
| } |
| |
| // Compatible integer types (in particular, usize vs ptr-sized-u32/u64). |
| // `char` counts as `u32.` |
| 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), |
| ty::Char => (Integer::I32, /* 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 interp_ok(caller == callee); |
| } |
| |
| // Fall back to exact equality. |
| interp_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. |
| // (This can fail e.g. if `#[rustc_nonnull_optimization_guaranteed]` is used incorrectly.) |
| assert!(caller_abi.eq_abi(callee_abi)); |
| interp_ok(true) |
| } else { |
| trace!( |
| "check_argument_compat: incompatible ABIs:\ncaller: {:?}\ncallee: {:?}", |
| caller_abi, callee_abi |
| ); |
| interp_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 interp_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_allow_transmute(&caller_arg_copy, &callee_arg)?; |
| // If this was an in-place pass, protect the place it comes from for the duration of the call. |
| if let FnArg::InPlace(mplace) = caller_arg { |
| M::protect_in_place_function_argument(self, mplace)?; |
| } |
| interp_ok(()) |
| } |
| |
| /// The main entry point for creating a new stack frame: performs ABI checks and initializes |
| /// arguments. |
| #[instrument(skip(self), level = "trace")] |
| pub fn init_stack_frame( |
| &mut self, |
| instance: Instance<'tcx>, |
| body: &'tcx mir::Body<'tcx>, |
| caller_fn_abi: &FnAbi<'tcx, Ty<'tcx>>, |
| args: &[FnArg<'tcx, M::Provenance>], |
| with_caller_location: bool, |
| destination: &MPlaceTy<'tcx, M::Provenance>, |
| mut stack_pop: StackPopCleanup, |
| ) -> InterpResult<'tcx> { |
| // Compute callee information. |
| // 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 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. |
| M::check_fn_target_features(self, instance)?; |
| |
| if !callee_fn_abi.can_unwind { |
| // The callee cannot unwind, so force the `Unreachable` unwind handling. |
| match &mut stack_pop { |
| StackPopCleanup::Root { .. } => {} |
| StackPopCleanup::Goto { unwind, .. } => { |
| *unwind = mir::UnwindAction::Unreachable; |
| } |
| } |
| } |
| |
| self.push_stack_frame_raw(instance, body, destination, stack_pop)?; |
| |
| // 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_fn_abi, |
| args.iter() |
| .map(|arg| (arg.layout().ty, match arg { |
| FnArg::Copy(op) => format!("copy({op:?})"), |
| FnArg::InPlace(mplace) => format!("in-place({mplace:?})"), |
| })) |
| .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. |
| |
| // The "where they come from" part is easy, we expect the caller to do any special handling |
| // that might be required here (e.g. for untupling). |
| // If `with_caller_location` is set we pretend there is an extra argument (that |
| // we will not pass; our `caller_location` intrinsic implementation walks the stack instead). |
| assert_eq!( |
| 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 = 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 instantiation we need to get the |
| // type, but the result gets cached so this avoids calling the instantiation |
| // 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 |
| }); |
| } |
| |
| // Protect return place for in-place return value passing. |
| 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()?; |
| }; |
| res.inspect_err(|_| { |
| // Don't show the incomplete stack frame in the error stacktrace. |
| self.stack_mut().pop(); |
| }) |
| } |
| |
| /// Initiate a call to 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(super) fn init_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: &MPlaceTy<'tcx, M::Provenance>, |
| target: Option<mir::BasicBlock>, |
| unwind: mir::UnwindAction, |
| ) -> InterpResult<'tcx> { |
| trace!("init_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::InstanceKind::Intrinsic(def_id) => { |
| assert!(self.tcx.intrinsic(def_id).is_some()); |
| // FIXME: Should `InPlace` arguments be reset to uninit? |
| if let Some(fallback) = M::call_intrinsic( |
| self, |
| instance, |
| &self.copy_fn_args(args), |
| destination, |
| target, |
| unwind, |
| )? { |
| assert!(!self.tcx.intrinsic(fallback.def_id()).unwrap().must_be_overridden); |
| assert_matches!(fallback.def, ty::InstanceKind::Item(_)); |
| return self.init_fn_call( |
| FnVal::Instance(fallback), |
| (caller_abi, caller_fn_abi), |
| args, |
| with_caller_location, |
| destination, |
| target, |
| unwind, |
| ); |
| } else { |
| interp_ok(()) |
| } |
| } |
| ty::InstanceKind::VTableShim(..) |
| | ty::InstanceKind::ReifyShim(..) |
| | ty::InstanceKind::ClosureOnceShim { .. } |
| | ty::InstanceKind::ConstructCoroutineInClosureShim { .. } |
| | ty::InstanceKind::FnPtrShim(..) |
| | ty::InstanceKind::DropGlue(..) |
| | ty::InstanceKind::CloneShim(..) |
| | ty::InstanceKind::FnPtrAddrShim(..) |
| | ty::InstanceKind::ThreadLocalShim(..) |
| | ty::InstanceKind::AsyncDropGlueCtorShim(..) |
| | ty::InstanceKind::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 interp_ok(()); |
| }; |
| |
| // Special handling for the closure ABI: untuple the last argument. |
| let args: Cow<'_, [FnArg<'tcx, M::Provenance>]> = |
| if caller_abi == Abi::RustCall && !args.is_empty() { |
| // Untuple |
| let (untuple_arg, args) = args.split_last().unwrap(); |
| trace!("init_fn_call: Will pass last argument by untupling"); |
| Cow::from( |
| args.iter() |
| .map(|a| interp_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) |
| }; |
| |
| self.init_stack_frame( |
| instance, |
| body, |
| caller_fn_abi, |
| &args, |
| with_caller_location, |
| destination, |
| StackPopCleanup::Goto { ret: target, unwind }, |
| ) |
| } |
| // `InstanceKind::Virtual` does not have callable MIR. Calls to `Virtual` instances must be |
| // codegen'd / interpreted as virtual calls through the vtable. |
| ty::InstanceKind::Virtual(def_id, idx) => { |
| let mut args = args.to_vec(); |
| // We have to implement all "dyn-compatible 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 (trait_, dyn_ty, adjusted_recv) = if let ty::Dynamic(data, _, ty::DynStar) = |
| receiver_place.layout.ty.kind() |
| { |
| let recv = self.unpack_dyn_star(&receiver_place, data)?; |
| |
| (data.principal(), recv.layout.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_for_codegen(receiver_place.layout.ty, self.param_env); |
| let ty::Dynamic(receiver_trait, _, 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 = self.get_ptr_vtable_ty(vptr, Some(receiver_trait))?; |
| |
| // 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. |
| (receiver_trait.principal(), dyn_ty, receiver_place.ptr()) |
| }; |
| |
| // Now determine the actual method to call. Usually we use the easy way of just |
| // looking up the method at index `idx`. |
| let vtable_entries = self.vtable_entries(trait_, dyn_ty); |
| let Some(ty::VtblEntry::Method(fn_inst)) = vtable_entries.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:#?}"); |
| // We can also do the lookup based on `def_id` and `dyn_ty`, and check that that |
| // produces the same result. |
| 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::expect_resolve_for_vtable( |
| tcx, |
| self.param_env, |
| def_id, |
| instance.args.rebase_onto(tcx, trait_def_id, concrete_trait_ref.args), |
| self.cur_span(), |
| ); |
| 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_recv, 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.init_fn_call( |
| FnVal::Instance(fn_inst), |
| (caller_abi, &caller_fn_abi), |
| &args, |
| with_caller_location, |
| destination, |
| target, |
| unwind, |
| ) |
| } |
| } |
| } |
| |
| /// Initiate a tail call to this function -- popping the current stack frame, pushing the new |
| /// stack frame and initializing the arguments. |
| pub(super) fn init_fn_tail_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, |
| ) -> InterpResult<'tcx> { |
| trace!("init_fn_tail_call: {:#?}", fn_val); |
| |
| // This is the "canonical" implementation of tails calls, |
| // a pop of the current stack frame, followed by a normal call |
| // which pushes a new stack frame, with the return address from |
| // the popped stack frame. |
| // |
| // Note that we are using `pop_stack_frame_raw` and not `return_from_current_stack_frame`, |
| // as the latter "executes" the goto to the return block, but we don't want to, |
| // only the tail called function should return to the current return block. |
| M::before_stack_pop(self, self.frame())?; |
| |
| let StackPopInfo { return_action, return_to_block, return_place } = |
| self.pop_stack_frame_raw(false)?; |
| |
| assert_eq!(return_action, ReturnAction::Normal); |
| |
| // Take the "stack pop cleanup" info, and use that to initiate the next call. |
| let StackPopCleanup::Goto { ret, unwind } = return_to_block else { |
| bug!("can't tailcall as root"); |
| }; |
| |
| // FIXME(explicit_tail_calls): |
| // we should check if both caller&callee can/n't unwind, |
| // see <https://github.com/rust-lang/rust/pull/113128#issuecomment-1614979803> |
| |
| self.init_fn_call( |
| fn_val, |
| (caller_abi, caller_fn_abi), |
| args, |
| with_caller_location, |
| &return_place, |
| ret, |
| unwind, |
| ) |
| } |
| |
| pub(super) fn init_drop_in_place_call( |
| &mut self, |
| place: &PlaceTy<'tcx, M::Provenance>, |
| instance: ty::Instance<'tcx>, |
| target: mir::BasicBlock, |
| unwind: mir::UnwindAction, |
| ) -> InterpResult<'tcx> { |
| trace!("init_drop_in_place_call: {:?},\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)?; |
| |
| // We behave a bit different from codegen here. |
| // Codegen creates an `InstanceKind::Virtual` with index 0 (the slot of the drop method) and |
| // then dispatches that to the normal call machinery. However, our call machinery currently |
| // only supports calling `VtblEntry::Method`; it would choke on a `MetadataDropInPlace`. So |
| // instead we do the virtual call stuff ourselves. It's easier here than in `eval_fn_call` |
| // since we can just get a place of the underlying type and use `mplace_to_ref`. |
| let place = match place.layout.ty.kind() { |
| ty::Dynamic(data, _, ty::Dyn) => { |
| // Dropping a trait object. Need to find actual drop fn. |
| self.unpack_dyn_trait(&place, data)? |
| } |
| ty::Dynamic(data, _, ty::DynStar) => { |
| // Dropping a `dyn*`. Need to find actual drop fn. |
| self.unpack_dyn_star(&place, data)? |
| } |
| _ => { |
| 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.init_fn_call( |
| FnVal::Instance(instance), |
| (Abi::Rust, fn_abi), |
| &[FnArg::Copy(arg.into())], |
| false, |
| &ret, |
| Some(target), |
| unwind, |
| ) |
| } |
| |
| /// Pops the current frame from the stack, copies the return value to the caller, deallocates |
| /// the memory for allocated locals, and jumps to an appropriate place. |
| /// |
| /// If `unwinding` is `false`, then we are performing a normal return |
| /// from a function. In this case, we jump back into the frame of the caller, |
| /// and continue execution as normal. |
| /// |
| /// If `unwinding` is `true`, then we are in the middle of a panic, |
| /// and need to unwind this frame. In this case, we jump to the |
| /// `cleanup` block for the function, which is responsible for running |
| /// `Drop` impls for any locals that have been initialized at this point. |
| /// The cleanup block ends with a special `Resume` terminator, which will |
| /// cause us to continue unwinding. |
| #[instrument(skip(self), level = "trace")] |
| pub(super) fn return_from_current_stack_frame( |
| &mut self, |
| unwinding: bool, |
| ) -> InterpResult<'tcx> { |
| info!( |
| "popping stack frame ({})", |
| if unwinding { "during unwinding" } else { "returning from function" } |
| ); |
| |
| // Check `unwinding`. |
| assert_eq!(unwinding, match self.frame().loc { |
| Left(loc) => self.body().basic_blocks[loc.block].is_cleanup, |
| Right(_) => true, |
| }); |
| if unwinding && self.frame_idx() == 0 { |
| throw_ub_custom!(fluent::const_eval_unwind_past_top); |
| } |
| |
| M::before_stack_pop(self, self.frame())?; |
| |
| // Copy return value. Must of course happen *before* we deallocate the locals. |
| // Must be *after* `before_stack_pop` as otherwise the return place might still be protected. |
| let copy_ret_result = if !unwinding { |
| let op = self |
| .local_to_op(mir::RETURN_PLACE, None) |
| .expect("return place should always be live"); |
| let dest = self.frame().return_place.clone(); |
| let res = if self.stack().len() == 1 { |
| // The initializer of constants and statics will get validated separately |
| // after the constant has been fully evaluated. While we could fall back to the default |
| // code path, that will cause -Zenforce-validity to cycle on static initializers. |
| // Reading from a static's memory is not allowed during its evaluation, and will always |
| // trigger a cycle error. Validation must read from the memory of the current item. |
| // For Miri this means we do not validate the root frame return value, |
| // but Miri anyway calls `read_target_isize` on that so separate validation |
| // is not needed. |
| self.copy_op_no_dest_validation(&op, &dest) |
| } else { |
| self.copy_op_allow_transmute(&op, &dest) |
| }; |
| trace!("return value: {:?}", self.dump_place(&dest.into())); |
| // We delay actually short-circuiting on this error until *after* the stack frame is |
| // popped, since we want this error to be attributed to the caller, whose type defines |
| // this transmute. |
| res |
| } else { |
| interp_ok(()) |
| }; |
| |
| // All right, now it is time to actually pop the frame. |
| // An error here takes precedence over the copy error. |
| let (stack_pop_info, ()) = self.pop_stack_frame_raw(unwinding).and(copy_ret_result)?; |
| |
| match stack_pop_info.return_action { |
| ReturnAction::Normal => {} |
| ReturnAction::NoJump => { |
| // The hook already did everything. |
| return interp_ok(()); |
| } |
| ReturnAction::NoCleanup => { |
| // If we are not doing cleanup, also skip everything else. |
| assert!(self.stack().is_empty(), "only the topmost frame should ever be leaked"); |
| assert!(!unwinding, "tried to skip cleanup during unwinding"); |
| // Skip machine hook. |
| return interp_ok(()); |
| } |
| } |
| |
| // Normal return, figure out where to jump. |
| if unwinding { |
| // Follow the unwind edge. |
| match stack_pop_info.return_to_block { |
| StackPopCleanup::Goto { unwind, .. } => { |
| // This must be the very last thing that happens, since it can in fact push a new stack frame. |
| self.unwind_to_block(unwind) |
| } |
| StackPopCleanup::Root { .. } => { |
| panic!("encountered StackPopCleanup::Root when unwinding!") |
| } |
| } |
| } else { |
| // Follow the normal return edge. |
| match stack_pop_info.return_to_block { |
| StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret), |
| StackPopCleanup::Root { .. } => { |
| assert!( |
| self.stack().is_empty(), |
| "only the bottommost frame can have StackPopCleanup::Root" |
| ); |
| interp_ok(()) |
| } |
| } |
| } |
| } |
| } |
