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Auto merge of #102906 - nbdd0121:mir, r=wesleywiser,tmiasko

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Refactor unwind in MIR

This makes unwinding from current `Option<BasicBlock>` into
```rust
enum UnwindAction {
	Continue,
	Cleanup(BasicBlock),
	Unreachable,
	Terminate,
}
```

cc `@JakobDegen` `@RalfJung` `@Amanieu`
This commit is contained in:
bors 2023-04-07 10:31:14 +00:00
commit da14081468
294 changed files with 1225 additions and 933 deletions
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10
compiler/rustc_const_eval/src/const_eval/machine.rs
View file

@ -23,7 +23,7 @@ use rustc_target::spec::abi::Abi as CallAbi;
use crate::interpret::{
self, compile_time_machine, AllocId, ConstAllocation, FnVal, Frame, ImmTy, InterpCx,
InterpResult, OpTy, PlaceTy, Pointer, Scalar, StackPopUnwind,
InterpResult, OpTy, PlaceTy, Pointer, Scalar,
};
use super::error::*;
@ -271,7 +271,7 @@ impl<'mir, 'tcx: 'mir> CompileTimeEvalContext<'mir, 'tcx> {
/* with_caller_location = */ false,
dest,
ret,
StackPopUnwind::NotAllowed,
mir::UnwindAction::Unreachable,
)?;
Ok(ControlFlow::Break(()))
} else {
@ -401,7 +401,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
args: &[OpTy<'tcx>],
dest: &PlaceTy<'tcx>,
ret: Option<mir::BasicBlock>,
_unwind: StackPopUnwind, // unwinding is not supported in consts
_unwind: mir::UnwindAction, // unwinding is not supported in consts
) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>> {
debug!("find_mir_or_eval_fn: {:?}", instance);
@ -450,7 +450,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
args: &[OpTy<'tcx>],
dest: &PlaceTy<'tcx, Self::Provenance>,
target: Option<mir::BasicBlock>,
_unwind: StackPopUnwind,
_unwind: mir::UnwindAction,
) -> InterpResult<'tcx> {
// Shared intrinsics.
if ecx.emulate_intrinsic(instance, args, dest, target)? {
@ -526,7 +526,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
fn assert_panic(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
msg: &AssertMessage<'tcx>,
_unwind: Option<mir::BasicBlock>,
_unwind: mir::UnwindAction,
) -> InterpResult<'tcx> {
use rustc_middle::mir::AssertKind::*;
// Convert `AssertKind<Operand>` to `AssertKind<Scalar>`.

29
compiler/rustc_const_eval/src/interpret/eval_context.rs
View file

@ -139,17 +139,6 @@ pub struct FrameInfo<'tcx> {
pub lint_root: Option<hir::HirId>,
}
/// Unwind information.
#[derive(Clone, Copy, Eq, PartialEq, Debug)]
pub enum StackPopUnwind {
/// The cleanup block.
Cleanup(mir::BasicBlock),
/// No cleanup needs to be done.
Skip,
/// Unwinding is not allowed (UB).
NotAllowed,
}
#[derive(Clone, Copy, Eq, PartialEq, Debug)] // Miri debug-prints these
pub enum StackPopCleanup {
/// Jump to the next block in the caller, or cause UB if None (that's a function
@ -157,7 +146,7 @@ pub enum StackPopCleanup {
/// we can validate it at that layout.
/// `ret` stores the block we jump to on a normal return, while `unwind`
/// stores the block used for cleanup during unwinding.
Goto { ret: Option<mir::BasicBlock>, unwind: StackPopUnwind },
Goto { ret: Option<mir::BasicBlock>, unwind: mir::UnwindAction },
/// The root frame of the stack: nowhere else to jump to.
/// `cleanup` says whether locals are deallocated. Static computation
/// wants them leaked to intern what they need (and just throw away
@ -735,18 +724,22 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
/// *Unwind* to the given `target` basic block.
/// Do *not* use for returning! Use `return_to_block` instead.
///
/// If `target` is `StackPopUnwind::Skip`, that indicates the function does not need cleanup
/// If `target` is `UnwindAction::Continue`, that indicates the function does not need cleanup
/// during unwinding, and we will just keep propagating that upwards.
///
/// If `target` is `StackPopUnwind::NotAllowed`, that indicates the function does not allow
/// If `target` is `UnwindAction::Unreachable`, that indicates the function does not allow
/// unwinding, and doing so is UB.
pub fn unwind_to_block(&mut self, target: StackPopUnwind) -> InterpResult<'tcx> {
pub fn unwind_to_block(&mut self, target: mir::UnwindAction) -> InterpResult<'tcx> {
self.frame_mut().loc = match target {
StackPopUnwind::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
StackPopUnwind::Skip => Right(self.frame_mut().body.span),
StackPopUnwind::NotAllowed => {
mir::UnwindAction::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
mir::UnwindAction::Continue => Right(self.frame_mut().body.span),
mir::UnwindAction::Unreachable => {
throw_ub_format!("unwinding past a stack frame that does not allow unwinding")
}
mir::UnwindAction::Terminate => {
self.frame_mut().loc = Right(self.frame_mut().body.span);
M::abort(self, "panic in a function that cannot unwind".to_owned())?;
}
};
Ok(())
}

14
compiler/rustc_const_eval/src/interpret/machine.rs
View file

@ -18,7 +18,7 @@ use crate::const_eval::CheckAlignment;
use super::{
AllocBytes, AllocId, AllocRange, Allocation, ConstAllocation, Frame, ImmTy, InterpCx,
InterpResult, MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar, StackPopUnwind,
InterpResult, MemoryKind, OpTy, Operand, PlaceTy, Pointer, Provenance, Scalar,
};
/// Data returned by Machine::stack_pop,
@ -185,7 +185,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
args: &[OpTy<'tcx, Self::Provenance>],
destination: &PlaceTy<'tcx, Self::Provenance>,
target: Option<mir::BasicBlock>,
unwind: StackPopUnwind,
unwind: mir::UnwindAction,
) -> InterpResult<'tcx, Option<(&'mir mir::Body<'tcx>, ty::Instance<'tcx>)>>;
/// Execute `fn_val`. It is the hook's responsibility to advance the instruction
@ -197,7 +197,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
args: &[OpTy<'tcx, Self::Provenance>],
destination: &PlaceTy<'tcx, Self::Provenance>,
target: Option<mir::BasicBlock>,
unwind: StackPopUnwind,
unwind: mir::UnwindAction,
) -> InterpResult<'tcx>;
/// Directly process an intrinsic without pushing a stack frame. It is the hook's
@ -208,17 +208,17 @@ pub trait Machine<'mir, 'tcx>: Sized {
args: &[OpTy<'tcx, Self::Provenance>],
destination: &PlaceTy<'tcx, Self::Provenance>,
target: Option<mir::BasicBlock>,
unwind: StackPopUnwind,
unwind: mir::UnwindAction,
) -> InterpResult<'tcx>;
/// Called to evaluate `Assert` MIR terminators that trigger a panic.
fn assert_panic(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
msg: &mir::AssertMessage<'tcx>,
unwind: Option<mir::BasicBlock>,
unwind: mir::UnwindAction,
) -> InterpResult<'tcx>;
/// Called to evaluate `Abort` MIR terminator.
/// Called to abort evaluation.
fn abort(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _msg: String) -> InterpResult<'tcx, !> {
throw_unsup_format!("aborting execution is not supported")
}
@ -487,7 +487,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
_args: &[OpTy<$tcx>],
_destination: &PlaceTy<$tcx, Self::Provenance>,
_target: Option<mir::BasicBlock>,
_unwind: StackPopUnwind,
_unwind: mir::UnwindAction,
) -> InterpResult<$tcx> {
match fn_val {}
}

4
compiler/rustc_const_eval/src/interpret/mod.rs
View file

@ -20,9 +20,7 @@ mod visitor;
pub use rustc_middle::mir::interpret::*; // have all the `interpret` symbols in one place: here
pub use self::eval_context::{
Frame, FrameInfo, InterpCx, LocalState, LocalValue, StackPopCleanup, StackPopUnwind,
};
pub use self::eval_context::{Frame, FrameInfo, InterpCx, LocalState, LocalValue, StackPopCleanup};
pub use self::intern::{intern_const_alloc_recursive, InternKind};
pub use self::machine::{compile_time_machine, AllocMap, Machine, MayLeak, StackPopJump};
pub use self::memory::{AllocKind, AllocRef, AllocRefMut, FnVal, Memory, MemoryKind};

34
compiler/rustc_const_eval/src/interpret/terminator.rs
View file

@ -13,7 +13,7 @@ use rustc_target::spec::abi::Abi;
use super::{
FnVal, ImmTy, Immediate, InterpCx, InterpResult, MPlaceTy, Machine, MemoryKind, OpTy, Operand,
PlaceTy, Scalar, StackPopCleanup, StackPopUnwind,
PlaceTy, Scalar, StackPopCleanup,
};
impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@ -60,7 +60,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
ref args,
destination,
target,
ref cleanup,
unwind,
from_hir_call: _,
fn_span: _,
} => {
@ -106,11 +106,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
with_caller_location,
&destination,
target,
match (cleanup, fn_abi.can_unwind) {
(Some(cleanup), true) => StackPopUnwind::Cleanup(*cleanup),
(None, true) => StackPopUnwind::Skip,
(_, false) => StackPopUnwind::NotAllowed,
},
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.
@ -137,19 +133,20 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
self.drop_in_place(&place, instance, target, unwind)?;
}
Assert { ref cond, expected, ref msg, target, cleanup } => {
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, cleanup)?;
M::assert_panic(self, msg, unwind)?;
}
}
Abort => {
M::abort(self, "the program aborted execution".to_owned())?;
Terminate => {
// FIXME: maybe should call `panic_no_unwind` lang item instead.
M::abort(self, "panic in a function that cannot unwind".to_owned())?;
}
// When we encounter Resume, we've finished unwinding
@ -351,7 +348,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
with_caller_location: bool,
destination: &PlaceTy<'tcx, M::Provenance>,
target: Option<mir::BasicBlock>,
mut unwind: StackPopUnwind,
mut unwind: mir::UnwindAction,
) -> InterpResult<'tcx> {
trace!("eval_fn_call: {:#?}", fn_val);
@ -410,9 +407,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
}
if !matches!(unwind, StackPopUnwind::NotAllowed) && !callee_fn_abi.can_unwind {
// The callee cannot unwind.
unwind = StackPopUnwind::NotAllowed;
if !callee_fn_abi.can_unwind {
// The callee cannot unwind, so force the `Unreachable` unwind handling.
unwind = mir::UnwindAction::Unreachable;
}
self.push_stack_frame(
@ -676,7 +673,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
place: &PlaceTy<'tcx, M::Provenance>,
instance: ty::Instance<'tcx>,
target: mir::BasicBlock,
unwind: Option<mir::BasicBlock>,
unwind: mir::UnwindAction,
) -> 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
@ -717,10 +714,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
false,
&ret.into(),
Some(target),
match unwind {
Some(cleanup) => StackPopUnwind::Cleanup(cleanup),
None => StackPopUnwind::Skip,
},
unwind,
)
}
}

4
compiler/rustc_const_eval/src/transform/check_consts/check.rs
View file

@ -1031,9 +1031,9 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
self.check_op(ops::Generator(hir::GeneratorKind::Gen))
}
TerminatorKind::Abort => {
TerminatorKind::Terminate => {
// Cleanup blocks are skipped for const checking (see `visit_basic_block_data`).
span_bug!(self.span, "`Abort` terminator outside of cleanup block")
span_bug!(self.span, "`Terminate` terminator outside of cleanup block")
}
TerminatorKind::Assert { .. }

2
compiler/rustc_const_eval/src/transform/check_consts/post_drop_elaboration.rs
View file

@ -104,7 +104,7 @@ impl<'tcx> Visitor<'tcx> for CheckLiveDrops<'_, 'tcx> {
}
}
mir::TerminatorKind::Abort
mir::TerminatorKind::Terminate
| mir::TerminatorKind::Call { .. }
| mir::TerminatorKind::Assert { .. }
| mir::TerminatorKind::FalseEdge { .. }

2
compiler/rustc_const_eval/src/transform/promote_consts.rs
View file

@ -807,7 +807,7 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
kind: TerminatorKind::Call {
func,
args,
cleanup: None,
unwind: UnwindAction::Continue,
destination: Place::from(new_temp),
target: Some(new_target),
from_hir_call,

53
compiler/rustc_const_eval/src/transform/validate.rs
View file

@ -10,7 +10,7 @@ use rustc_middle::mir::{
traversal, BasicBlock, BinOp, Body, BorrowKind, CastKind, CopyNonOverlapping, Local, Location,
MirPass, MirPhase, NonDivergingIntrinsic, Operand, Place, PlaceElem, PlaceRef, ProjectionElem,
RetagKind, RuntimePhase, Rvalue, SourceScope, Statement, StatementKind, Terminator,
TerminatorKind, UnOp, VarDebugInfo, VarDebugInfoContents, START_BLOCK,
TerminatorKind, UnOp, UnwindAction, VarDebugInfo, VarDebugInfoContents, START_BLOCK,
};
use rustc_middle::ty::{self, InstanceDef, ParamEnv, Ty, TyCtxt, TypeVisitableExt};
use rustc_mir_dataflow::impls::MaybeStorageLive;
@ -232,6 +232,24 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
}
}
fn check_unwind_edge(&mut self, location: Location, unwind: UnwindAction) {
let is_cleanup = self.body.basic_blocks[location.block].is_cleanup;
match unwind {
UnwindAction::Cleanup(unwind) => {
if is_cleanup {
self.fail(location, "unwind on cleanup block");
}
self.check_edge(location, unwind, EdgeKind::Unwind);
}
UnwindAction::Continue => {
if is_cleanup {
self.fail(location, "unwind on cleanup block");
}
}
UnwindAction::Unreachable | UnwindAction::Terminate => (),
}
}
/// Check if src can be assigned into dest.
/// This is not precise, it will accept some incorrect assignments.
fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
@ -902,11 +920,9 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
}
TerminatorKind::Drop { target, unwind, .. } => {
self.check_edge(location, *target, EdgeKind::Normal);
if let Some(unwind) = unwind {
self.check_edge(location, *unwind, EdgeKind::Unwind);
}
self.check_unwind_edge(location, *unwind);
}
TerminatorKind::Call { func, args, destination, target, cleanup, .. } => {
TerminatorKind::Call { func, args, destination, target, unwind, .. } => {
let func_ty = func.ty(&self.body.local_decls, self.tcx);
match func_ty.kind() {
ty::FnPtr(..) | ty::FnDef(..) => {}
@ -918,9 +934,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
if let Some(target) = target {
self.check_edge(location, *target, EdgeKind::Normal);
}
if let Some(cleanup) = cleanup {
self.check_edge(location, *cleanup, EdgeKind::Unwind);
}
self.check_unwind_edge(location, *unwind);
// The call destination place and Operand::Move place used as an argument might be
// passed by a reference to the callee. Consequently they must be non-overlapping.
@ -946,7 +960,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
}
TerminatorKind::Assert { cond, target, cleanup, .. } => {
TerminatorKind::Assert { cond, target, unwind, .. } => {
let cond_ty = cond.ty(&self.body.local_decls, self.tcx);
if cond_ty != self.tcx.types.bool {
self.fail(
@ -958,9 +972,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
self.check_edge(location, *target, EdgeKind::Normal);
if let Some(cleanup) = cleanup {
self.check_edge(location, *cleanup, EdgeKind::Unwind);
}
self.check_unwind_edge(location, *unwind);
}
TerminatorKind::Yield { resume, drop, .. } => {
if self.body.generator.is_none() {
@ -992,17 +1004,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
self.check_edge(location, *real_target, EdgeKind::Normal);
if let Some(unwind) = unwind {
self.check_edge(location, *unwind, EdgeKind::Unwind);
}
self.check_unwind_edge(location, *unwind);
}
TerminatorKind::InlineAsm { destination, cleanup, .. } => {
TerminatorKind::InlineAsm { destination, unwind, .. } => {
if let Some(destination) = destination {
self.check_edge(location, *destination, EdgeKind::Normal);
}
if let Some(cleanup) = cleanup {
self.check_edge(location, *cleanup, EdgeKind::Unwind);
}
self.check_unwind_edge(location, *unwind);
}
TerminatorKind::GeneratorDrop => {
if self.body.generator.is_none() {
@ -1015,10 +1023,13 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
);
}
}
TerminatorKind::Resume | TerminatorKind::Abort => {
TerminatorKind::Resume | TerminatorKind::Terminate => {
let bb = location.block;
if !self.body.basic_blocks[bb].is_cleanup {
self.fail(location, "Cannot `Resume` or `Abort` from non-cleanup basic block")
self.fail(
location,
"Cannot `Resume` or `Terminate` from non-cleanup basic block",
)
}
}
TerminatorKind::Return => {