4 use rustc::ty::Instance;
5 use rustc::ty::layout::{self, TyLayout, LayoutOf};
6 use syntax::source_map::Span;
7 use rustc_target::spec::abi::Abi;
9 use rustc::mir::interpret::{InterpResult, PointerArithmetic, InterpError, Scalar};
11 InterpretCx, Machine, Immediate, OpTy, ImmTy, PlaceTy, MPlaceTy, StackPopCleanup
14 impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpretCx<'mir, 'tcx, M> {
16 pub fn goto_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
17 if let Some(target) = target {
18 self.frame_mut().block = target;
19 self.frame_mut().stmt = 0;
26 pub(super) fn eval_terminator(
28 terminator: &mir::Terminator<'tcx>,
29 ) -> InterpResult<'tcx> {
30 use rustc::mir::TerminatorKind::*;
31 match terminator.kind {
33 self.frame().return_place.map(|r| self.dump_place(*r));
34 self.pop_stack_frame()?
37 Goto { target } => self.goto_block(Some(target))?,
45 let discr = self.read_immediate(self.eval_operand(discr, None)?)?;
46 trace!("SwitchInt({:?})", *discr);
48 // Branch to the `otherwise` case by default, if no match is found.
49 let mut target_block = targets[targets.len() - 1];
51 for (index, &const_int) in values.iter().enumerate() {
52 // Compare using binary_op, to also support pointer values
53 let const_int = Scalar::from_uint(const_int, discr.layout.size);
54 let (res, _) = self.binary_op(mir::BinOp::Eq,
56 ImmTy::from_scalar(const_int, discr.layout),
59 target_block = targets[index];
64 self.goto_block(Some(target_block))?;
73 let (dest, ret) = match *destination {
74 Some((ref lv, target)) => (Some(self.eval_place(lv)?), Some(target)),
78 let func = self.eval_operand(func, None)?;
79 let (fn_def, abi) = match func.layout.ty.sty {
81 let caller_abi = sig.abi();
82 let fn_ptr = self.force_ptr(self.read_scalar(func)?.not_undef()?)?;
83 let instance = self.memory.get_fn(fn_ptr)?;
84 (instance, caller_abi)
86 ty::FnDef(def_id, substs) => {
87 let sig = func.layout.ty.fn_sig(*self.tcx);
88 (self.resolve(def_id, substs)?, sig.abi())
91 let msg = format!("can't handle callee of type {:?}", func.layout.ty);
92 return err!(Unimplemented(msg));
95 let args = self.eval_operands(args)?;
98 terminator.source_info.span,
111 // FIXME(CTFE): forbid drop in const eval
112 let place = self.eval_place(location)?;
113 let ty = place.layout.ty;
114 trace!("TerminatorKind::drop: {:?}, type {}", location, ty);
116 let instance = Instance::resolve_drop_in_place(*self.tcx, ty);
120 terminator.source_info.span,
132 let cond_val = self.read_immediate(self.eval_operand(cond, None)?)?
133 .to_scalar()?.to_bool()?;
134 if expected == cond_val {
135 self.goto_block(Some(target))?;
137 // Compute error message
138 use rustc::mir::interpret::InterpError::*;
140 BoundsCheck { ref len, ref index } => {
141 let len = self.read_immediate(self.eval_operand(len, None)?)
142 .expect("can't eval len").to_scalar()?
143 .to_bits(self.memory().pointer_size())? as u64;
144 let index = self.read_immediate(self.eval_operand(index, None)?)
145 .expect("can't eval index").to_scalar()?
146 .to_bits(self.memory().pointer_size())? as u64;
147 err!(BoundsCheck { len, index })
149 Overflow(op) => Err(Overflow(op).into()),
150 OverflowNeg => Err(OverflowNeg.into()),
151 DivisionByZero => Err(DivisionByZero.into()),
152 RemainderByZero => Err(RemainderByZero.into()),
153 GeneratorResumedAfterReturn |
154 GeneratorResumedAfterPanic => unimplemented!(),
162 DropAndReplace { .. } |
164 Abort => unimplemented!("{:#?}", terminator.kind),
165 FalseEdges { .. } => bug!("should have been eliminated by\
166 `simplify_branches` mir pass"),
167 FalseUnwind { .. } => bug!("should have been eliminated by\
168 `simplify_branches` mir pass"),
169 Unreachable => return err!(Unreachable),
175 fn check_argument_compat(
177 caller: TyLayout<'tcx>,
178 callee: TyLayout<'tcx>,
180 if caller.ty == callee.ty {
185 // Don't risk anything
189 match (&caller.abi, &callee.abi) {
190 // Different valid ranges are okay (once we enforce validity,
191 // that will take care to make it UB to leave the range, just
192 // like for transmute).
193 (layout::Abi::Scalar(ref caller), layout::Abi::Scalar(ref callee)) =>
194 caller.value == callee.value,
195 (layout::Abi::ScalarPair(ref caller1, ref caller2),
196 layout::Abi::ScalarPair(ref callee1, ref callee2)) =>
197 caller1.value == callee1.value && caller2.value == callee2.value,
203 /// Pass a single argument, checking the types for compatibility.
207 caller_arg: &mut impl Iterator<Item=OpTy<'tcx, M::PointerTag>>,
208 callee_arg: PlaceTy<'tcx, M::PointerTag>,
209 ) -> InterpResult<'tcx> {
210 if rust_abi && callee_arg.layout.is_zst() {
212 trace!("Skipping callee ZST");
215 let caller_arg = caller_arg.next()
216 .ok_or_else(|| InterpError::FunctionArgCountMismatch)?;
218 debug_assert!(!caller_arg.layout.is_zst(), "ZSTs must have been already filtered out");
221 if !Self::check_argument_compat(rust_abi, caller_arg.layout, callee_arg.layout) {
222 return err!(FunctionArgMismatch(caller_arg.layout.ty, callee_arg.layout.ty));
224 // We allow some transmutes here
225 self.copy_op_transmute(caller_arg, callee_arg)
228 /// Call this function -- pushing the stack frame and initializing the arguments.
231 instance: ty::Instance<'tcx>,
234 args: &[OpTy<'tcx, M::PointerTag>],
235 dest: Option<PlaceTy<'tcx, M::PointerTag>>,
236 ret: Option<mir::BasicBlock>,
237 ) -> InterpResult<'tcx> {
238 trace!("eval_fn_call: {:#?}", instance);
241 ty::InstanceDef::Intrinsic(..) => {
242 if caller_abi != Abi::RustIntrinsic {
243 return err!(FunctionAbiMismatch(caller_abi, Abi::RustIntrinsic));
245 // The intrinsic itself cannot diverge, so if we got here without a return
246 // place... (can happen e.g., for transmute returning `!`)
247 let dest = match dest {
249 None => return err!(Unreachable)
251 M::call_intrinsic(self, instance, args, dest)?;
252 // No stack frame gets pushed, the main loop will just act as if the
254 self.goto_block(ret)?;
255 self.dump_place(*dest);
258 ty::InstanceDef::VtableShim(..) |
259 ty::InstanceDef::ClosureOnceShim { .. } |
260 ty::InstanceDef::FnPtrShim(..) |
261 ty::InstanceDef::DropGlue(..) |
262 ty::InstanceDef::CloneShim(..) |
263 ty::InstanceDef::Item(_) => {
267 let instance_ty = instance.ty(*self.tcx);
268 match instance_ty.sty {
270 instance_ty.fn_sig(*self.tcx).abi(),
271 ty::Closure(..) => Abi::RustCall,
272 ty::Generator(..) => Abi::Rust,
273 _ => bug!("unexpected callee ty: {:?}", instance_ty),
276 // Rust and RustCall are compatible
277 let normalize_abi = |abi| if abi == Abi::RustCall { Abi::Rust } else { abi };
278 if normalize_abi(caller_abi) != normalize_abi(callee_abi) {
279 return err!(FunctionAbiMismatch(caller_abi, callee_abi));
283 // We need MIR for this fn
284 let body = match M::find_fn(self, instance, args, dest, ret)? {
286 None => return Ok(()),
289 self.push_stack_frame(
294 StackPopCleanup::Goto(ret),
297 // We want to pop this frame again in case there was an error, to put
298 // the blame in the right location. Until the 2018 edition is used in
299 // the compiler, we have to do this with an immediately invoked function.
302 "caller ABI: {:?}, args: {:#?}",
305 .map(|arg| (arg.layout.ty, format!("{:?}", **arg)))
309 "spread_arg: {:?}, locals: {:#?}",
313 (local, self.layout_of_local(self.frame(), local, None).unwrap().ty)
318 // Figure out how to pass which arguments.
319 // The Rust ABI is special: ZST get skipped.
320 let rust_abi = match caller_abi {
321 Abi::Rust | Abi::RustCall => true,
324 // We have two iterators: Where the arguments come from,
325 // and where they go to.
327 // For where they come from: If the ABI is RustCall, we untuple the
328 // last incoming argument. These two iterators do not have the same type,
329 // so to keep the code paths uniform we accept an allocation
330 // (for RustCall ABI only).
331 let caller_args : Cow<'_, [OpTy<'tcx, M::PointerTag>]> =
332 if caller_abi == Abi::RustCall && !args.is_empty() {
334 let (&untuple_arg, args) = args.split_last().unwrap();
335 trace!("eval_fn_call: Will pass last argument by untupling");
336 Cow::from(args.iter().map(|&a| Ok(a))
337 .chain((0..untuple_arg.layout.fields.count()).into_iter()
338 .map(|i| self.operand_field(untuple_arg, i as u64))
340 .collect::<InterpResult<'_, Vec<OpTy<'tcx, M::PointerTag>>>>()?)
346 let mut caller_iter = caller_args.iter()
347 .filter(|op| !rust_abi || !op.layout.is_zst())
350 // Now we have to spread them out across the callee's locals,
351 // taking into account the `spread_arg`. If we could write
352 // this is a single iterator (that handles `spread_arg`), then
353 // `pass_argument` would be the loop body. It takes care to
354 // not advance `caller_iter` for ZSTs.
355 let mut locals_iter = body.args_iter();
356 while let Some(local) = locals_iter.next() {
357 let dest = self.eval_place(
358 &mir::Place::Base(mir::PlaceBase::Local(local))
360 if Some(local) == body.spread_arg {
362 for i in 0..dest.layout.fields.count() {
363 let dest = self.place_field(dest, i as u64)?;
364 self.pass_argument(rust_abi, &mut caller_iter, dest)?;
368 self.pass_argument(rust_abi, &mut caller_iter, dest)?;
371 // Now we should have no more caller args
372 if caller_iter.next().is_some() {
373 trace!("Caller has passed too many args");
374 return err!(FunctionArgCountMismatch);
376 // Don't forget to check the return type!
377 if let Some(caller_ret) = dest {
378 let callee_ret = self.eval_place(
379 &mir::Place::RETURN_PLACE
381 if !Self::check_argument_compat(
386 return err!(FunctionRetMismatch(
387 caller_ret.layout.ty, callee_ret.layout.ty
392 self.layout_of_local(self.frame(), mir::RETURN_PLACE, None)?;
393 if !callee_layout.abi.is_uninhabited() {
394 return err!(FunctionRetMismatch(
395 self.tcx.types.never, callee_layout.ty
409 // cannot use the shim here, because that will only result in infinite recursion
410 ty::InstanceDef::Virtual(_, idx) => {
411 let mut args = args.to_vec();
412 let ptr_size = self.pointer_size();
413 // We have to implement all "object safe receivers". Currently we
414 // support built-in pointers (&, &mut, Box) as well as unsized-self. We do
415 // not yet support custom self types.
416 // Also see librustc_codegen_llvm/abi.rs and librustc_codegen_llvm/mir/block.rs.
417 let receiver_place = match args[0].layout.ty.builtin_deref(true) {
420 self.deref_operand(args[0])?
424 args[0].to_mem_place()
427 // Find and consult vtable
428 let vtable = receiver_place.vtable();
429 let vtable_slot = vtable.ptr_offset(ptr_size * (idx as u64 + 3), self)?;
430 let vtable_slot = self.memory.check_ptr_access(
433 self.tcx.data_layout.pointer_align.abi,
434 )?.expect("cannot be a ZST");
435 let fn_ptr = self.memory.get(vtable_slot.alloc_id)?
436 .read_ptr_sized(self, vtable_slot)?.to_ptr()?;
437 let instance = self.memory.get_fn(fn_ptr)?;
439 // `*mut receiver_place.layout.ty` is almost the layout that we
440 // want for args[0]: We have to project to field 0 because we want
442 assert!(receiver_place.layout.is_unsized());
443 let receiver_ptr_ty = self.tcx.mk_mut_ptr(receiver_place.layout.ty);
444 let this_receiver_ptr = self.layout_of(receiver_ptr_ty)?.field(self, 0)?;
445 // Adjust receiver argument.
446 args[0] = OpTy::from(ImmTy {
447 layout: this_receiver_ptr,
448 imm: Immediate::Scalar(receiver_place.ptr.into())
450 trace!("Patched self operand to {:#?}", args[0]);
451 // recurse with concrete function
452 self.eval_fn_call(instance, span, caller_abi, &args, dest, ret)
459 place: PlaceTy<'tcx, M::PointerTag>,
460 instance: ty::Instance<'tcx>,
462 target: mir::BasicBlock,
463 ) -> InterpResult<'tcx> {
464 trace!("drop_in_place: {:?},\n {:?}, {:?}", *place, place.layout.ty, instance);
465 // We take the address of the object. This may well be unaligned, which is fine
466 // for us here. However, unaligned accesses will probably make the actual drop
467 // implementation fail -- a problem shared by rustc.
468 let place = self.force_allocation(place)?;
470 let (instance, place) = match place.layout.ty.sty {
472 // Dropping a trait object.
473 self.unpack_dyn_trait(place)?
475 _ => (instance, place),
480 layout: self.layout_of(self.tcx.mk_mut_ptr(place.layout.ty))?,
483 let ty = self.tcx.mk_unit(); // return type is ()
484 let dest = MPlaceTy::dangling(self.layout_of(ty)?, self);