Skip to content

Commit 73ff6c9

Browse files
tmiaskotmiasko
committed
Custom MIR: Support cleanup blocks
Cleanup blocks are declared with `bb (cleanup) = { ... }`. `Call` and `Drop` terminators take an additional argument describing the unwind action, which is one of the following: * `UnwindContinue()` * `UnwindUnreachable()` * `UnwindTerminate(reason)`, where reason is `Abi` or `InCleanup` * `UnwindCleanup(block)` Also support resume and terminate terminators: * `Resume()` * `Terminate(reason)`
1 parent 91bbdd9 commit 73ff6c9

36 files changed

+316
-83
lines changed

‎compiler/rustc_mir_build/src/build/custom/parse.rs‎

Lines changed: 29 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,10 @@ macro_rules! parse_by_kind {
3030
@call($name:literal, $args:ident) => $call_expr:expr,
3131
)*
3232
$(
33-
$pat:pat => $expr:expr,
33+
@variant($adt:literal, $variant:literal) => $variant_expr:expr,
34+
)*
35+
$(
36+
$pat:pat $(if $guard:expr)? => $expr:expr,
3437
)*
3538
) => {{
3639
let expr_id = $self.preparse($expr_id);
@@ -49,7 +52,13 @@ macro_rules! parse_by_kind {
4952
} => $call_expr,
5053
)*
5154
$(
52-
$pat => $expr,
55+
ExprKind::Adt(box AdtExpr { adt_def, variant_index, .. }) if {
56+
$self.tcx.is_diagnostic_item(rustc_span::Symbol::intern($adt), adt_def.did()) &&
57+
adt_def.variants()[*variant_index].name == rustc_span::Symbol::intern($variant)
58+
} => $variant_expr,
59+
)*
60+
$(
61+
$pat $(if $guard)? => $expr,
5362
)*
5463
#[allow(unreachable_patterns)]
5564
_ => return Err($self.expr_error(expr_id, $expected))
@@ -172,7 +181,8 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
172181
ExprKind::Block { block } => &self.thir[*block].stmts,
173182
);
174183
for (i, block_def) in block_defs.iter().enumerate() {
175-
let block = self.parse_block_def(self.statement_as_expr(*block_def)?)?;
184+
let is_cleanup = self.body.basic_blocks_mut()[BasicBlock::from_usize(i)].is_cleanup;
185+
let block = self.parse_block_def(self.statement_as_expr(*block_def)?, is_cleanup)?;
176186
self.body.basic_blocks_mut()[BasicBlock::from_usize(i)] = block;
177187
}
178188

@@ -181,8 +191,9 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
181191

182192
fn parse_block_decls(&mut self, stmts: impl Iterator<Item = StmtId>) -> PResult<()> {
183193
for stmt in stmts {
184-
let (var, _, _) = self.parse_let_statement(stmt)?;
185-
let data = BasicBlockData::new(None);
194+
let (var, _, _, initializer) = self.parse_let_statement(stmt)?;
195+
let mut data = BasicBlockData::new(None);
196+
data.is_cleanup = initializer.is_some();
186197
let block = self.body.basic_blocks_mut().push(data);
187198
self.block_map.insert(var, block);
188199
}
@@ -195,7 +206,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
195206
self.local_map.insert(ret_var, Local::from_u32(0));
196207

197208
for stmt in stmts {
198-
let (var, ty, span) = self.parse_let_statement(stmt)?;
209+
let (var, ty, span, _) = self.parse_let_statement(stmt)?;
199210
let decl = LocalDecl::new(ty, span);
200211
let local = self.body.local_decls.push(decl);
201212
self.local_map.insert(var, local);
@@ -251,15 +262,17 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
251262
Ok(())
252263
}
253264

254-
fn parse_let_statement(&mut self, stmt_id: StmtId) -> PResult<(LocalVarId, Ty<'tcx>, Span)> {
255-
let pattern = match &self.thir[stmt_id].kind {
256-
StmtKind::Let { pattern, .. } => pattern,
257-
StmtKind::Expr { expr, .. } => {
258-
return Err(self.expr_error(*expr, "let statement"));
265+
fn parse_let_statement(
266+
&mut self,
267+
stmt_id: StmtId,
268+
) -> PResult<(LocalVarId, Ty<'tcx>, Span, Option<ExprId>)> {
269+
match &self.thir[stmt_id].kind {
270+
StmtKind::Let { pattern, initializer, .. } => {
271+
let (var, ty, span) = self.parse_var(pattern)?;
272+
Ok((var, ty, span, *initializer))
259273
}
260-
};
261-
262-
self.parse_var(pattern)
274+
StmtKind::Expr { expr, .. } => Err(self.expr_error(*expr, "let statement")),
275+
}
263276
}
264277

265278
fn parse_var(&mut self, mut pat: &Pat<'tcx>) -> PResult<(LocalVarId, Ty<'tcx>, Span)> {
@@ -281,12 +294,13 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
281294
}
282295
}
283296

284-
fn parse_block_def(&self, expr_id: ExprId) -> PResult<BasicBlockData<'tcx>> {
297+
fn parse_block_def(&self, expr_id: ExprId, is_cleanup: bool) -> PResult<BasicBlockData<'tcx>> {
285298
let block = parse_by_kind!(self, expr_id, _, "basic block",
286299
ExprKind::Block { block } => &self.thir[*block],
287300
);
288301

289302
let mut data = BasicBlockData::new(None);
303+
data.is_cleanup = is_cleanup;
290304
for stmt_id in &*block.stmts {
291305
let stmt = self.statement_as_expr(*stmt_id)?;
292306
let span = self.thir[stmt].span;

‎compiler/rustc_mir_build/src/build/custom/parse/instruction.rs‎

Lines changed: 37 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -52,11 +52,17 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
5252
@call("mir_unreachable", _args) => {
5353
Ok(TerminatorKind::Unreachable)
5454
},
55+
@call("mir_resume", _args) => {
56+
Ok(TerminatorKind::UnwindResume)
57+
},
58+
@call("mir_terminate", args) => {
59+
Ok(TerminatorKind::UnwindTerminate(self.parse_unwind_terminate_reason(args[0])?))
60+
},
5561
@call("mir_drop", args) => {
5662
Ok(TerminatorKind::Drop {
5763
place: self.parse_place(args[0])?,
5864
target: self.parse_block(args[1])?,
59-
unwind: UnwindAction::Continue,
65+
unwind: self.parse_unwind_action(args[2])?,
6066
replace: false,
6167
})
6268
},
@@ -70,6 +76,34 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
7076
)
7177
}
7278

79+
fn parse_unwind_terminate_reason(&self, expr_id: ExprId) -> PResult<UnwindTerminateReason> {
80+
parse_by_kind!(self, expr_id, _, "unwind terminate reason",
81+
@variant("mir_unwind_terminate_reason", "Abi") => {
82+
Ok(UnwindTerminateReason::Abi)
83+
},
84+
@variant("mir_unwind_terminate_reason", "InCleanup") => {
85+
Ok(UnwindTerminateReason::InCleanup)
86+
},
87+
)
88+
}
89+
90+
fn parse_unwind_action(&self, expr_id: ExprId) -> PResult<UnwindAction> {
91+
parse_by_kind!(self, expr_id, _, "unwind action",
92+
@call("mir_unwind_continue", _args) => {
93+
Ok(UnwindAction::Continue)
94+
},
95+
@call("mir_unwind_unreachable", _args) => {
96+
Ok(UnwindAction::Unreachable)
97+
},
98+
@call("mir_unwind_terminate", args) => {
99+
Ok(UnwindAction::Terminate(self.parse_unwind_terminate_reason(args[0])?))
100+
},
101+
@call("mir_unwind_cleanup", args) => {
102+
Ok(UnwindAction::Cleanup(self.parse_block(args[0])?))
103+
},
104+
)
105+
}
106+
73107
fn parse_match(&self, arms: &[ArmId], span: Span) -> PResult<SwitchTargets> {
74108
let Some((otherwise, rest)) = arms.split_last() else {
75109
return Err(ParseError {
@@ -113,6 +147,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
113147
);
114148
let destination = self.parse_place(destination)?;
115149
let target = self.parse_block(args[1])?;
150+
let unwind = self.parse_unwind_action(args[2])?;
116151

117152
parse_by_kind!(self, call, _, "function call",
118153
ExprKind::Call { fun, args, from_hir_call, fn_span, .. } => {
@@ -126,7 +161,7 @@ impl<'tcx, 'body> ParseCtxt<'tcx, 'body> {
126161
args,
127162
destination,
128163
target: Some(target),
129-
unwind: UnwindAction::Continue,
164+
unwind,
130165
call_source: if *from_hir_call { CallSource::Normal } else {
131166
CallSource::OverloadedOperator
132167
},

‎library/backtrace‎

Submodule backtrace updated 31 files

‎library/core/src/intrinsics/mir.rs‎

Lines changed: 43 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -110,15 +110,15 @@
110110
//! let popped;
111111
//!
112112
//! {
113-
//! Call(_unused = Vec::push(v, value), pop)
113+
//! Call(_unused = Vec::push(v, value), pop, UnwindContinue())
114114
//! }
115115
//!
116116
//! pop = {
117-
//! Call(popped = Vec::pop(v), drop)
117+
//! Call(popped = Vec::pop(v), drop, UnwindContinue())
118118
//! }
119119
//!
120120
//! drop = {
121-
//! Drop(popped, ret)
121+
//! Drop(popped, ret, UnwindContinue())
122122
//! }
123123
//!
124124
//! ret = {
@@ -238,10 +238,6 @@
238238
//!
239239
//! #### Terminators
240240
//!
241-
//! Custom MIR does not currently support cleanup blocks or non-trivial unwind paths. As such, there
242-
//! are no resume and abort terminators, and terminators that might unwind do not have any way to
243-
//! indicate the unwind block.
244-
//!
245241
//! - [`Goto`], [`Return`], [`Unreachable`] and [`Drop`](Drop()) have associated functions.
246242
//! - `match some_int_operand` becomes a `SwitchInt`. Each arm should be `literal => basic_block`
247243
//! - The exception is the last arm, which must be `_ => basic_block` and corresponds to the
@@ -262,6 +258,18 @@
262258
/// All terminators will have this type as a return type. It helps achieve some type safety.
263259
pub struct BasicBlock;
264260

261+
/// The reason we are terminating the process during unwinding.
262+
#[rustc_diagnostic_item = "mir_unwind_terminate_reason"]
263+
pub enum UnwindTerminateReason {
264+
/// Unwinding is just not possible given the ABI of this function.
265+
Abi,
266+
/// We were already cleaning up for an ongoing unwind, and a *second*, *nested* unwind was
267+
/// triggered by the drop glue.
268+
InCleanup,
269+
}
270+
271+
pub use UnwindTerminateReason::*;
272+
265273
macro_rules! define {
266274
($name:literal, $( #[ $meta:meta ] )* fn $($sig:tt)*) => {
267275
#[rustc_diagnostic_item = $name]
@@ -270,12 +278,17 @@ macro_rules! define {
270278
pub fn $($sig)* { panic!() }
271279
}
272280
}
273-
274281
define!("mir_return", fn Return() -> BasicBlock);
275282
define!("mir_goto", fn Goto(destination: BasicBlock) -> BasicBlock);
276283
define!("mir_unreachable", fn Unreachable() -> BasicBlock);
277-
define!("mir_drop", fn Drop<T>(place: T, goto: BasicBlock));
278-
define!("mir_call", fn Call(call: (), goto: BasicBlock));
284+
define!("mir_resume", fn Resume());
285+
define!("mir_terminate", fn Terminate(reason: UnwindTerminateReason));
286+
define!("mir_drop", fn Drop<T, U>(place: T, goto: BasicBlock, unwind_action: U));
287+
define!("mir_call", fn Call<U>(call: (), goto: BasicBlock, unwind_action: U));
288+
define!("mir_unwind_continue", fn UnwindContinue());
289+
define!("mir_unwind_unreachable", fn UnwindUnreachable() -> BasicBlock);
290+
define!("mir_unwind_terminate", fn UnwindTerminate(reason: UnwindTerminate));
291+
define!("mir_unwind_cleanup", fn UnwindCleanup(goto: BasicBlock));
279292
define!("mir_storage_live", fn StorageLive<T>(local: T));
280293
define!("mir_storage_dead", fn StorageDead<T>(local: T));
281294
define!("mir_deinit", fn Deinit<T>(place: T));
@@ -382,16 +395,15 @@ pub macro mir {
382395
}
383396

384397
$(
385-
$block_name:ident = {
398+
$block_name:ident $(($block_cleanup:ident))? = {
386399
$($block:tt)*
387400
}
388401
)*
389402
) => {{
390403
// First, we declare all basic blocks.
391-
$(
392-
let $block_name: ::core::intrinsics::mir::BasicBlock;
393-
)*
394-
404+
__internal_declare_basic_blocks!($(
405+
$block_name $(($block_cleanup))?
406+
)*);
395407
{
396408
// Now all locals
397409
#[allow(non_snake_case)]
@@ -585,3 +597,19 @@ pub macro __internal_remove_let {
585597
}
586598
},
587599
}
600+
601+
/// Helper macro that declares the basic blocks.
602+
///
603+
/// The cleanup block are distinguished by an initializer.
604+
#[doc(hidden)]
605+
pub macro __internal_declare_basic_blocks {
606+
() => {},
607+
($name:ident (cleanup) $($rest:tt)*) => {
608+
let $name = ::core::intrinsics::mir::BasicBlock;
609+
__internal_declare_basic_blocks!($($rest)*)
610+
},
611+
($name:ident $($rest:tt)*) => {
612+
let $name : ::core::intrinsics::mir::BasicBlock;
613+
__internal_declare_basic_blocks!($($rest)*)
614+
},
615+
}

‎src/tools/miri/tests/fail/function_calls/arg_inplace_mutate.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@ fn main() {
1414
let ptr = std::ptr::addr_of_mut!(non_copy);
1515
// Inside `callee`, the first argument and `*ptr` are basically
1616
// aliasing places!
17-
Call(_unit = callee(Move(*ptr), ptr), after_call)
17+
Call(_unit = callee(Move(*ptr), ptr), after_call, UnwindContinue())
1818
}
1919
after_call = {
2020
Return()

‎src/tools/miri/tests/fail/function_calls/arg_inplace_mutate.stack.stderr‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -27,8 +27,8 @@ LL | unsafe { ptr.write(S(0)) };
2727
note: inside `main`
2828
--> $DIR/arg_inplace_mutate.rs:LL:CC
2929
|
30-
LL | Call(_unit = callee(Move(*ptr), ptr), after_call)
31-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
30+
LL | Call(_unit = callee(Move(*ptr), ptr), after_call, UnwindContinue())
31+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3232
= note: this error originates in the macro `::core::intrinsics::mir::__internal_remove_let` which comes from the expansion of the macro `mir` (in Nightly builds, run with -Z macro-backtrace for more info)
3333

3434
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

‎src/tools/miri/tests/fail/function_calls/arg_inplace_mutate.tree.stderr‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -35,8 +35,8 @@ LL | unsafe { ptr.write(S(0)) };
3535
note: inside `main`
3636
--> $DIR/arg_inplace_mutate.rs:LL:CC
3737
|
38-
LL | Call(_unit = callee(Move(*ptr), ptr), after_call)
39-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
38+
LL | Call(_unit = callee(Move(*ptr), ptr), after_call, UnwindContinue())
39+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
4040
= note: this error originates in the macro `::core::intrinsics::mir::__internal_remove_let` which comes from the expansion of the macro `mir` (in Nightly builds, run with -Z macro-backtrace for more info)
4141

4242
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

‎src/tools/miri/tests/fail/function_calls/arg_inplace_observe_after.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@ fn main() {
1111
{
1212
let non_copy = S(42);
1313
// This could change `non_copy` in-place
14-
Call(_unit = change_arg(Move(non_copy)), after_call)
14+
Call(_unit = change_arg(Move(non_copy)), after_call, UnwindContinue())
1515
}
1616
after_call = {
1717
// So now we must not be allowed to observe non-copy again.

‎src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.none.stderr‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -11,8 +11,8 @@ LL | unsafe { ptr.read() };
1111
note: inside `main`
1212
--> $DIR/arg_inplace_observe_during.rs:LL:CC
1313
|
14-
LL | Call(_unit = change_arg(Move(*ptr), ptr), after_call)
15-
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
14+
LL | Call(_unit = change_arg(Move(*ptr), ptr), after_call, UnwindContinue())
15+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1616

1717
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
1818

‎src/tools/miri/tests/fail/function_calls/arg_inplace_observe_during.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@ fn main() {
1414
let non_copy = S(42);
1515
let ptr = std::ptr::addr_of_mut!(non_copy);
1616
// This could change `non_copy` in-place
17-
Call(_unit = change_arg(Move(*ptr), ptr), after_call)
17+
Call(_unit = change_arg(Move(*ptr), ptr), after_call, UnwindContinue())
1818
}
1919
after_call = {
2020
Return()

0 commit comments

Comments
 (0)