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Rollup merge of #143528 - RalfJung:stack-pop-cleanup, r=oli-obk
interpret: rename StackPopCleanup The name `StackPopCleanup` stopped making sense a long time ago IMO -- in the common case, it has nothing to do with "cleanup", and everything with where the program should jump next. If we didn't have unwinding this would be just the return block, but given that we do have unwinding I figured maybe "continuation" would be a good name. This comes up in [continuation-passing style](https://en.wikipedia.org/wiki/Continuation-passing_style) and refers to where the program will *continue* when a function is done. So from a PL perspective it is the most fitting term I think -- but it may be too jargony. r? `@oli-obk` what do you think?
2 parents 02aa4ff + 7775166 commit eed5594

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10 files changed

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‎compiler/rustc_const_eval/src/const_eval/eval_queries.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -19,7 +19,7 @@ use super::{CanAccessMutGlobal, CompileTimeInterpCx, CompileTimeMachine};
1919
use crate::const_eval::CheckAlignment;
2020
use crate::interpret::{
2121
CtfeValidationMode, GlobalId, Immediate, InternKind, InternResult, InterpCx, InterpErrorKind,
22-
InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking, StackPopCleanup, create_static_alloc,
22+
InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking, ReturnContinuation, create_static_alloc,
2323
intern_const_alloc_recursive, interp_ok, throw_exhaust,
2424
};
2525
use crate::{CTRL_C_RECEIVED, errors};
@@ -76,7 +76,7 @@ fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
7676
cid.instance,
7777
body,
7878
&ret.clone().into(),
79-
StackPopCleanup::Root { cleanup: false },
79+
ReturnContinuation::Stop { cleanup: false },
8080
)?;
8181
ecx.storage_live_for_always_live_locals()?;
8282

‎compiler/rustc_const_eval/src/interpret/call.rs

Lines changed: 18 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@ use tracing::{info, instrument, trace};
1515

1616
use super::{
1717
CtfeProvenance, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy,
18-
Projectable, Provenance, ReturnAction, Scalar, StackPopCleanup, StackPopInfo, interp_ok,
18+
Projectable, Provenance, ReturnAction, ReturnContinuation, Scalar, StackPopInfo, interp_ok,
1919
throw_ub, throw_ub_custom, throw_unsup_format,
2020
};
2121
use crate::fluent_generated as fluent;
@@ -340,7 +340,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
340340
args: &[FnArg<'tcx, M::Provenance>],
341341
with_caller_location: bool,
342342
destination: &PlaceTy<'tcx, M::Provenance>,
343-
mut stack_pop: StackPopCleanup,
343+
mut cont: ReturnContinuation,
344344
) -> InterpResult<'tcx> {
345345
// Compute callee information.
346346
// FIXME: for variadic support, do we have to somehow determine callee's extra_args?
@@ -365,15 +365,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
365365

366366
if !callee_fn_abi.can_unwind {
367367
// The callee cannot unwind, so force the `Unreachable` unwind handling.
368-
match &mut stack_pop {
369-
StackPopCleanup::Root { .. } => {}
370-
StackPopCleanup::Goto { unwind, .. } => {
368+
match &mut cont {
369+
ReturnContinuation::Stop { .. } => {}
370+
ReturnContinuation::Goto { unwind, .. } => {
371371
*unwind = mir::UnwindAction::Unreachable;
372372
}
373373
}
374374
}
375375

376-
self.push_stack_frame_raw(instance, body, destination, stack_pop)?;
376+
self.push_stack_frame_raw(instance, body, destination, cont)?;
377377

378378
// If an error is raised here, pop the frame again to get an accurate backtrace.
379379
// To this end, we wrap it all in a `try` block.
@@ -617,7 +617,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
617617
&args,
618618
with_caller_location,
619619
destination,
620-
StackPopCleanup::Goto { ret: target, unwind },
620+
ReturnContinuation::Goto { ret: target, unwind },
621621
)
622622
}
623623
// `InstanceKind::Virtual` does not have callable MIR. Calls to `Virtual` instances must be
@@ -755,16 +755,16 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
755755
// Note that we are using `pop_stack_frame_raw` and not `return_from_current_stack_frame`,
756756
// as the latter "executes" the goto to the return block, but we don't want to,
757757
// only the tail called function should return to the current return block.
758-
let StackPopInfo { return_action, return_to_block, return_place } = self
759-
.pop_stack_frame_raw(false, |_this, _return_place| {
758+
let StackPopInfo { return_action, return_cont, return_place } =
759+
self.pop_stack_frame_raw(false, |_this, _return_place| {
760760
// This function's return value is just discarded, the tail-callee will fill in the return place instead.
761761
interp_ok(())
762762
})?;
763763

764764
assert_eq!(return_action, ReturnAction::Normal);
765765

766766
// Take the "stack pop cleanup" info, and use that to initiate the next call.
767-
let StackPopCleanup::Goto { ret, unwind } = return_to_block else {
767+
let ReturnContinuation::Goto { ret, unwind } = return_cont else {
768768
bug!("can't tailcall as root");
769769
};
770770

@@ -896,23 +896,23 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
896896
// Normal return, figure out where to jump.
897897
if unwinding {
898898
// Follow the unwind edge.
899-
match stack_pop_info.return_to_block {
900-
StackPopCleanup::Goto { unwind, .. } => {
899+
match stack_pop_info.return_cont {
900+
ReturnContinuation::Goto { unwind, .. } => {
901901
// This must be the very last thing that happens, since it can in fact push a new stack frame.
902902
self.unwind_to_block(unwind)
903903
}
904-
StackPopCleanup::Root { .. } => {
905-
panic!("encountered StackPopCleanup::Root when unwinding!")
904+
ReturnContinuation::Stop { .. } => {
905+
panic!("encountered ReturnContinuation::Stop when unwinding!")
906906
}
907907
}
908908
} else {
909909
// Follow the normal return edge.
910-
match stack_pop_info.return_to_block {
911-
StackPopCleanup::Goto { ret, .. } => self.return_to_block(ret),
912-
StackPopCleanup::Root { .. } => {
910+
match stack_pop_info.return_cont {
911+
ReturnContinuation::Goto { ret, .. } => self.return_to_block(ret),
912+
ReturnContinuation::Stop { .. } => {
913913
assert!(
914914
self.stack().is_empty(),
915-
"only the bottommost frame can have StackPopCleanup::Root"
915+
"only the bottommost frame can have ReturnContinuation::Stop"
916916
);
917917
interp_ok(())
918918
}

‎compiler/rustc_const_eval/src/interpret/mod.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,7 @@ pub use self::operand::{ImmTy, Immediate, OpTy};
3636
pub use self::place::{MPlaceTy, MemPlaceMeta, PlaceTy, Writeable};
3737
use self::place::{MemPlace, Place};
3838
pub use self::projection::{OffsetMode, Projectable};
39-
pub use self::stack::{Frame, FrameInfo, LocalState, StackPopCleanup, StackPopInfo};
39+
pub use self::stack::{Frame, FrameInfo, LocalState, ReturnContinuation, StackPopInfo};
4040
pub(crate) use self::util::create_static_alloc;
4141
pub use self::validity::{CtfeValidationMode, RangeSet, RefTracking};
4242
pub use self::visitor::ValueVisitor;

‎compiler/rustc_const_eval/src/interpret/stack.rs

Lines changed: 19 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -72,8 +72,8 @@ pub struct Frame<'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
7272
////////////////////////////////////////////////////////////////////////////////
7373
// Return place and locals
7474
////////////////////////////////////////////////////////////////////////////////
75-
/// Work to perform when returning from this function.
76-
return_to_block: StackPopCleanup,
75+
/// Where to continue when returning from this function.
76+
return_cont: ReturnContinuation,
7777

7878
/// The location where the result of the current stack frame should be written to,
7979
/// and its layout in the caller. This place is to be interpreted relative to the
@@ -106,19 +106,19 @@ pub struct Frame<'tcx, Prov: Provenance = CtfeProvenance, Extra = ()> {
106106
pub(super) loc: Either<mir::Location, Span>,
107107
}
108108

109+
/// Where and how to continue when returning/unwinding from the current function.
109110
#[derive(Clone, Copy, Eq, PartialEq, Debug)] // Miri debug-prints these
110-
pub enum StackPopCleanup {
111+
pub enum ReturnContinuation {
111112
/// Jump to the next block in the caller, or cause UB if None (that's a function
112-
/// that may never return). Also store layout of return place so
113-
/// we can validate it at that layout.
113+
/// that may never return).
114114
/// `ret` stores the block we jump to on a normal return, while `unwind`
115115
/// stores the block used for cleanup during unwinding.
116116
Goto { ret: Option<mir::BasicBlock>, unwind: mir::UnwindAction },
117-
/// The root frame of the stack: nowhere else to jump to.
117+
/// The root frame of the stack: nowhere else to jump to, so we stop.
118118
/// `cleanup` says whether locals are deallocated. Static computation
119119
/// wants them leaked to intern what they need (and just throw away
120120
/// the entire `ecx` when it is done).
121-
Root { cleanup: bool },
121+
Stop { cleanup: bool },
122122
}
123123

124124
/// Return type of [`InterpCx::pop_stack_frame_raw`].
@@ -127,8 +127,8 @@ pub struct StackPopInfo<'tcx, Prov: Provenance> {
127127
/// stack frame.
128128
pub return_action: ReturnAction,
129129

130-
/// [`return_to_block`](Frame::return_to_block) of the popped stack frame.
131-
pub return_to_block: StackPopCleanup,
130+
/// [`return_cont`](Frame::return_cont) of the popped stack frame.
131+
pub return_cont: ReturnContinuation,
132132

133133
/// [`return_place`](Frame::return_place) of the popped stack frame.
134134
pub return_place: PlaceTy<'tcx, Prov>,
@@ -255,7 +255,7 @@ impl<'tcx, Prov: Provenance> Frame<'tcx, Prov> {
255255
Frame {
256256
body: self.body,
257257
instance: self.instance,
258-
return_to_block: self.return_to_block,
258+
return_cont: self.return_cont,
259259
return_place: self.return_place,
260260
locals: self.locals,
261261
loc: self.loc,
@@ -350,20 +350,20 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
350350
/// the arguments or local variables.
351351
///
352352
/// The high-level version of this is `init_stack_frame`.
353-
#[instrument(skip(self, body, return_place, return_to_block), level = "debug")]
353+
#[instrument(skip(self, body, return_place, return_cont), level = "debug")]
354354
pub(crate) fn push_stack_frame_raw(
355355
&mut self,
356356
instance: ty::Instance<'tcx>,
357357
body: &'tcx mir::Body<'tcx>,
358358
return_place: &PlaceTy<'tcx, M::Provenance>,
359-
return_to_block: StackPopCleanup,
359+
return_cont: ReturnContinuation,
360360
) -> InterpResult<'tcx> {
361361
trace!("body: {:#?}", body);
362362

363363
// We can push a `Root` frame if and only if the stack is empty.
364364
debug_assert_eq!(
365365
self.stack().is_empty(),
366-
matches!(return_to_block, StackPopCleanup::Root { .. })
366+
matches!(return_cont, ReturnContinuation::Stop { .. })
367367
);
368368

369369
// First push a stack frame so we have access to `instantiate_from_current_frame` and other
@@ -373,7 +373,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
373373
let pre_frame = Frame {
374374
body,
375375
loc: Right(body.span), // Span used for errors caused during preamble.
376-
return_to_block,
376+
return_cont,
377377
return_place: return_place.clone(),
378378
locals,
379379
instance,
@@ -429,15 +429,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
429429
copy_ret_val(self, &frame.return_place)?;
430430
}
431431

432-
let return_to_block = frame.return_to_block;
432+
let return_cont = frame.return_cont;
433433
let return_place = frame.return_place.clone();
434434

435435
// Cleanup: deallocate locals.
436436
// Usually we want to clean up (deallocate locals), but in a few rare cases we don't.
437437
// We do this while the frame is still on the stack, so errors point to the callee.
438-
let cleanup = match return_to_block {
439-
StackPopCleanup::Goto { .. } => true,
440-
StackPopCleanup::Root { cleanup, .. } => cleanup,
438+
let cleanup = match return_cont {
439+
ReturnContinuation::Goto { .. } => true,
440+
ReturnContinuation::Stop { cleanup, .. } => cleanup,
441441
};
442442

443443
let return_action = if cleanup {
@@ -455,7 +455,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
455455
ReturnAction::NoCleanup
456456
};
457457

458-
interp_ok(StackPopInfo { return_action, return_to_block, return_place })
458+
interp_ok(StackPopInfo { return_action, return_cont, return_place })
459459
}
460460

461461
/// In the current stack frame, mark all locals as live that are not arguments and don't have

‎src/tools/miri/src/concurrency/thread.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -894,7 +894,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
894894
start_abi,
895895
&[func_arg],
896896
Some(&ret_place),
897-
StackPopCleanup::Root { cleanup: true },
897+
ReturnContinuation::Stop { cleanup: true },
898898
)?;
899899

900900
// Restore the old active thread frame.

‎src/tools/miri/src/eval.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -436,7 +436,7 @@ pub fn create_ecx<'tcx>(
436436
ImmTy::from_uint(sigpipe, ecx.machine.layouts.u8),
437437
],
438438
Some(&ret_place),
439-
StackPopCleanup::Root { cleanup: true },
439+
ReturnContinuation::Stop { cleanup: true },
440440
)?;
441441
}
442442
MiriEntryFnType::MiriStart => {
@@ -445,7 +445,7 @@ pub fn create_ecx<'tcx>(
445445
ExternAbi::Rust,
446446
&[argc, argv],
447447
Some(&ret_place),
448-
StackPopCleanup::Root { cleanup: true },
448+
ReturnContinuation::Stop { cleanup: true },
449449
)?;
450450
}
451451
}

‎src/tools/miri/src/helpers.rs

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -444,7 +444,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
444444
caller_abi: ExternAbi,
445445
args: &[ImmTy<'tcx>],
446446
dest: Option<&MPlaceTy<'tcx>>,
447-
stack_pop: StackPopCleanup,
447+
cont: ReturnContinuation,
448448
) -> InterpResult<'tcx> {
449449
let this = self.eval_context_mut();
450450

@@ -472,7 +472,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
472472
&args.iter().map(|a| FnArg::Copy(a.clone().into())).collect::<Vec<_>>(),
473473
/*with_caller_location*/ false,
474474
&dest.into(),
475-
stack_pop,
475+
cont,
476476
)
477477
}
478478

‎src/tools/miri/src/machine.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1199,7 +1199,7 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> {
11991199
ExternAbi::Rust,
12001200
&[],
12011201
None,
1202-
StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
1202+
ReturnContinuation::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
12031203
)?;
12041204
interp_ok(())
12051205
}

‎src/tools/miri/src/shims/panic.rs

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -92,7 +92,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
9292
&[data.clone()],
9393
None,
9494
// Directly return to caller.
95-
StackPopCleanup::Goto { ret, unwind: mir::UnwindAction::Continue },
95+
ReturnContinuation::Goto { ret, unwind: mir::UnwindAction::Continue },
9696
)?;
9797

9898
// We ourselves will return `0`, eventually (will be overwritten if we catch a panic).
@@ -143,7 +143,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
143143
&[catch_unwind.data, payload],
144144
None,
145145
// Directly return to caller of `catch_unwind`.
146-
StackPopCleanup::Goto {
146+
ReturnContinuation::Goto {
147147
ret: catch_unwind.ret,
148148
// `catch_fn` must not unwind.
149149
unwind: mir::UnwindAction::Unreachable,
@@ -172,7 +172,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
172172
ExternAbi::Rust,
173173
&[this.mplace_to_ref(&msg)?],
174174
None,
175-
StackPopCleanup::Goto { ret: None, unwind },
175+
ReturnContinuation::Goto { ret: None, unwind },
176176
)
177177
}
178178

@@ -191,7 +191,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
191191
ExternAbi::Rust,
192192
&[this.mplace_to_ref(&msg)?],
193193
None,
194-
StackPopCleanup::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
194+
ReturnContinuation::Goto { ret: None, unwind: mir::UnwindAction::Unreachable },
195195
)
196196
}
197197

@@ -220,7 +220,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
220220
ExternAbi::Rust,
221221
&[index, len],
222222
None,
223-
StackPopCleanup::Goto { ret: None, unwind },
223+
ReturnContinuation::Goto { ret: None, unwind },
224224
)?;
225225
}
226226
MisalignedPointerDereference { required, found } => {
@@ -241,7 +241,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
241241
ExternAbi::Rust,
242242
&[required, found],
243243
None,
244-
StackPopCleanup::Goto { ret: None, unwind },
244+
ReturnContinuation::Goto { ret: None, unwind },
245245
)?;
246246
}
247247

@@ -254,7 +254,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
254254
ExternAbi::Rust,
255255
&[],
256256
None,
257-
StackPopCleanup::Goto { ret: None, unwind },
257+
ReturnContinuation::Goto { ret: None, unwind },
258258
)?;
259259
}
260260
}

‎src/tools/miri/src/shims/tls.rs

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -325,7 +325,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
325325
ExternAbi::System { unwind: false },
326326
&[null_ptr.clone(), ImmTy::from_scalar(reason, this.machine.layouts.u32), null_ptr],
327327
None,
328-
StackPopCleanup::Root { cleanup: true },
328+
ReturnContinuation::Stop { cleanup: true },
329329
)?;
330330
interp_ok(())
331331
}
@@ -346,7 +346,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
346346
ExternAbi::C { unwind: false },
347347
&[ImmTy::from_scalar(data, this.machine.layouts.mut_raw_ptr)],
348348
None,
349-
StackPopCleanup::Root { cleanup: true },
349+
ReturnContinuation::Stop { cleanup: true },
350350
)?;
351351

352352
return interp_ok(Poll::Pending);
@@ -383,7 +383,7 @@ trait EvalContextPrivExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
383383
ExternAbi::C { unwind: false },
384384
&[ImmTy::from_scalar(ptr, this.machine.layouts.mut_raw_ptr)],
385385
None,
386-
StackPopCleanup::Root { cleanup: true },
386+
ReturnContinuation::Stop { cleanup: true },
387387
)?;
388388

389389
return interp_ok(Poll::Pending);

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