Rollup merge of #127472 - Zalathar:block-and-unit, r=fmease

MIR building: Stop using `unpack!` for `BlockAnd<()>`

This is a subset of #127416, containing only the parts related to `BlockAnd<()>`.

The first patch removes the non-assigning form of the `unpack!` macro, because it is frustratingly inconsistent with the main form. We can replace it with an ordinary method that discards the `()` and returns the block.

The second patch then finds all of the remaining code that was using `unpack!` with `BlockAnd<()>`, and updates it to use that new method instead.

---

Changes since original review of #127416:
- Renamed `fn unpack_block` → `fn into_block`
- Removed `fn unpack_discard`, replacing it with `let _: BlockAnd<()> = ...` (2 occurrences)
- Tweaked `arm_end_blocks` to unpack earlier and build `Vec<BasicBlock>` instead of `Vec<BlockAnd<()>>`
This commit is contained in:
Matthias Krüger 2024-07-17 16:22:28 +02:00 committed by GitHub
commit c98487e3be
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8 changed files with 86 additions and 73 deletions

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@ -71,11 +71,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
StmtKind::Expr { scope, expr } => {
this.block_context.push(BlockFrame::Statement { ignores_expr_result: true });
let si = (*scope, source_info);
unpack!(
block = this.in_scope(si, LintLevel::Inherited, |this| {
block = this
.in_scope(si, LintLevel::Inherited, |this| {
this.stmt_expr(block, *expr, Some(*scope))
})
);
.into_block();
}
StmtKind::Let {
remainder_scope,
@ -166,14 +166,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let dummy_place = this.temp(this.tcx.types.never, else_block_span);
let failure_entry = this.cfg.start_new_block();
let failure_block;
unpack!(
failure_block = this.ast_block(
failure_block = this
.ast_block(
dummy_place,
failure_entry,
*else_block,
this.source_info(else_block_span),
)
);
.into_block();
this.cfg.terminate(
failure_block,
this.source_info(else_block_span),
@ -267,8 +267,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let initializer_span = this.thir[init].span;
let scope = (*init_scope, source_info);
unpack!(
block = this.in_scope(scope, *lint_level, |this| {
block = this
.in_scope(scope, *lint_level, |this| {
this.declare_bindings(
visibility_scope,
remainder_span,
@ -279,10 +279,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
this.expr_into_pattern(block, &pattern, init)
// irrefutable pattern
})
)
.into_block();
} else {
let scope = (*init_scope, source_info);
unpack!(this.in_scope(scope, *lint_level, |this| {
let _: BlockAnd<()> = this.in_scope(scope, *lint_level, |this| {
this.declare_bindings(
visibility_scope,
remainder_span,
@ -291,7 +291,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
None,
);
block.unit()
}));
});
debug!("ast_block_stmts: pattern={:?}", pattern);
this.visit_primary_bindings(
@ -333,7 +333,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
this.block_context
.push(BlockFrame::TailExpr { tail_result_is_ignored, span: expr.span });
unpack!(block = this.expr_into_dest(destination, block, expr_id));
block = this.expr_into_dest(destination, block, expr_id).into_block();
let popped = this.block_context.pop();
assert!(popped.is_some_and(|bf| bf.is_tail_expr()));
@ -355,7 +355,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// Finally, we pop all the let scopes before exiting out from the scope of block
// itself.
for scope in let_scope_stack.into_iter().rev() {
unpack!(block = this.pop_scope((*scope, source_info), block));
block = this.pop_scope((*scope, source_info), block).into_block();
}
// Restore the original source scope.
this.source_scope = outer_source_scope;

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@ -185,13 +185,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
this.cfg.push_assign(block, source_info, Place::from(result), box_);
// initialize the box contents:
unpack!(
block = this.expr_into_dest(
this.tcx.mk_place_deref(Place::from(result)),
block,
value,
)
);
block = this
.expr_into_dest(this.tcx.mk_place_deref(Place::from(result)), block, value)
.into_block();
block.and(Rvalue::Use(Operand::Move(Place::from(result))))
}
ExprKind::Cast { source } => {
@ -486,7 +482,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
block.and(Rvalue::Aggregate(result, operands))
}
ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => {
block = unpack!(this.stmt_expr(block, expr_id, None));
block = this.stmt_expr(block, expr_id, None).into_block();
block.and(Rvalue::Use(Operand::Constant(Box::new(ConstOperand {
span: expr_span,
user_ty: None,

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@ -112,7 +112,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
}
unpack!(block = this.expr_into_dest(temp_place, block, expr_id));
block = this.expr_into_dest(temp_place, block, expr_id).into_block();
if let Some(temp_lifetime) = temp_lifetime {
this.schedule_drop(expr_span, temp_lifetime, temp, DropKind::Value);

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@ -82,13 +82,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// Lower the condition, and have it branch into `then` and `else` blocks.
let (then_block, else_block) =
this.in_if_then_scope(condition_scope, then_span, |this| {
let then_blk = unpack!(this.then_else_break(
block,
cond,
Some(condition_scope), // Temp scope
source_info,
DeclareLetBindings::Yes, // Declare `let` bindings normally
));
let then_blk = this
.then_else_break(
block,
cond,
Some(condition_scope), // Temp scope
source_info,
DeclareLetBindings::Yes, // Declare `let` bindings normally
)
.into_block();
// Lower the `then` arm into its block.
this.expr_into_dest(destination, then_blk, then)
@ -105,7 +107,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// If there is an `else` arm, lower it into `else_blk`.
if let Some(else_expr) = else_opt {
unpack!(else_blk = this.expr_into_dest(destination, else_blk, else_expr));
else_blk = this.expr_into_dest(destination, else_blk, else_expr).into_block();
} else {
// There is no `else` arm, so we know both arms have type `()`.
// Generate the implicit `else {}` by assigning unit.
@ -187,7 +189,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
const_: Const::from_bool(this.tcx, constant),
},
);
let mut rhs_block = unpack!(this.expr_into_dest(destination, continuation, rhs));
let mut rhs_block =
this.expr_into_dest(destination, continuation, rhs).into_block();
// Instrument the lowered RHS's value for condition coverage.
// (Does nothing if condition coverage is not enabled.)
this.visit_coverage_standalone_condition(rhs, destination, &mut rhs_block);
@ -230,7 +233,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// introduce a unit temporary as the destination for the loop body.
let tmp = this.get_unit_temp();
// Execute the body, branching back to the test.
let body_block_end = unpack!(this.expr_into_dest(tmp, body_block, body));
let body_block_end = this.expr_into_dest(tmp, body_block, body).into_block();
this.cfg.goto(body_block_end, source_info, loop_block);
// Loops are only exited by `break` expressions.
@ -462,7 +465,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
targets.push(target);
let tmp = this.get_unit_temp();
let target = unpack!(this.ast_block(tmp, target, block, source_info));
let target =
this.ast_block(tmp, target, block, source_info).into_block();
this.cfg.terminate(
target,
source_info,
@ -502,7 +506,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
// These cases don't actually need a destination
ExprKind::Assign { .. } | ExprKind::AssignOp { .. } => {
unpack!(block = this.stmt_expr(block, expr_id, None));
block = this.stmt_expr(block, expr_id, None).into_block();
this.cfg.push_assign_unit(block, source_info, destination, this.tcx);
block.unit()
}
@ -511,7 +515,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
| ExprKind::Break { .. }
| ExprKind::Return { .. }
| ExprKind::Become { .. } => {
unpack!(block = this.stmt_expr(block, expr_id, None));
block = this.stmt_expr(block, expr_id, None).into_block();
// No assign, as these have type `!`.
block.unit()
}

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@ -44,7 +44,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
if lhs_expr.ty.needs_drop(this.tcx, this.param_env) {
let rhs = unpack!(block = this.as_local_rvalue(block, rhs));
let lhs = unpack!(block = this.as_place(block, lhs));
unpack!(block = this.build_drop_and_replace(block, lhs_expr.span, lhs, rhs));
block =
this.build_drop_and_replace(block, lhs_expr.span, lhs, rhs).into_block();
} else {
let rhs = unpack!(block = this.as_local_rvalue(block, rhs));
let lhs = unpack!(block = this.as_place(block, lhs));

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@ -122,8 +122,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
match expr.kind {
ExprKind::LogicalOp { op: op @ LogicalOp::And, lhs, rhs } => {
this.visit_coverage_branch_operation(op, expr_span);
let lhs_then_block = unpack!(this.then_else_break_inner(block, lhs, args));
let rhs_then_block = unpack!(this.then_else_break_inner(lhs_then_block, rhs, args));
let lhs_then_block = this.then_else_break_inner(block, lhs, args).into_block();
let rhs_then_block =
this.then_else_break_inner(lhs_then_block, rhs, args).into_block();
rhs_then_block.unit()
}
ExprKind::LogicalOp { op: op @ LogicalOp::Or, lhs, rhs } => {
@ -140,14 +141,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
},
)
});
let rhs_success_block = unpack!(this.then_else_break_inner(
failure_block,
rhs,
ThenElseArgs {
declare_let_bindings: DeclareLetBindings::LetNotPermitted,
..args
},
));
let rhs_success_block = this
.then_else_break_inner(
failure_block,
rhs,
ThenElseArgs {
declare_let_bindings: DeclareLetBindings::LetNotPermitted,
..args
},
)
.into_block();
// Make the LHS and RHS success arms converge to a common block.
// (We can't just make LHS goto RHS, because `rhs_success_block`
@ -452,7 +455,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
outer_source_info: SourceInfo,
fake_borrow_temps: Vec<(Place<'tcx>, Local, FakeBorrowKind)>,
) -> BlockAnd<()> {
let arm_end_blocks: Vec<_> = arm_candidates
let arm_end_blocks: Vec<BasicBlock> = arm_candidates
.into_iter()
.map(|(arm, candidate)| {
debug!("lowering arm {:?}\ncandidate = {:?}", arm, candidate);
@ -503,6 +506,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
this.expr_into_dest(destination, arm_block, arm.body)
})
.into_block()
})
.collect();
@ -513,10 +517,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
outer_source_info.span.with_lo(outer_source_info.span.hi() - BytePos::from_usize(1)),
);
for arm_block in arm_end_blocks {
let block = &self.cfg.basic_blocks[arm_block.0];
let block = &self.cfg.basic_blocks[arm_block];
let last_location = block.statements.last().map(|s| s.source_info);
self.cfg.goto(unpack!(arm_block), last_location.unwrap_or(end_brace), end_block);
self.cfg.goto(arm_block, last_location.unwrap_or(end_brace), end_block);
}
self.source_scope = outer_source_info.scope;
@ -622,7 +626,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
OutsideGuard,
ScheduleDrops::Yes,
);
unpack!(block = self.expr_into_dest(place, block, initializer_id));
block = self.expr_into_dest(place, block, initializer_id).into_block();
// Inject a fake read, see comments on `FakeReadCause::ForLet`.
let source_info = self.source_info(irrefutable_pat.span);
@ -661,7 +665,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
OutsideGuard,
ScheduleDrops::Yes,
);
unpack!(block = self.expr_into_dest(place, block, initializer_id));
block = self.expr_into_dest(place, block, initializer_id).into_block();
// Inject a fake read, see comments on `FakeReadCause::ForLet`.
let pattern_source_info = self.source_info(irrefutable_pat.span);

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@ -403,6 +403,15 @@ enum NeedsTemporary {
#[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
struct BlockAnd<T>(BasicBlock, T);
impl BlockAnd<()> {
/// Unpacks `BlockAnd<()>` into a [`BasicBlock`].
#[must_use]
fn into_block(self) -> BasicBlock {
let Self(block, ()) = self;
block
}
}
trait BlockAndExtension {
fn and<T>(self, v: T) -> BlockAnd<T>;
fn unit(self) -> BlockAnd<()>;
@ -426,11 +435,6 @@ macro_rules! unpack {
$x = b;
v
}};
($c:expr) => {{
let BlockAnd(b, ()) = $c;
b
}};
}
///////////////////////////////////////////////////////////////////////////
@ -516,21 +520,22 @@ fn construct_fn<'tcx>(
region::Scope { id: body.id().hir_id.local_id, data: region::ScopeData::Arguments };
let source_info = builder.source_info(span);
let call_site_s = (call_site_scope, source_info);
unpack!(builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
let _: BlockAnd<()> = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
let arg_scope_s = (arg_scope, source_info);
// Attribute epilogue to function's closing brace
let fn_end = span_with_body.shrink_to_hi();
let return_block =
unpack!(builder.in_breakable_scope(None, Place::return_place(), fn_end, |builder| {
let return_block = builder
.in_breakable_scope(None, Place::return_place(), fn_end, |builder| {
Some(builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
builder.args_and_body(START_BLOCK, arguments, arg_scope, expr)
}))
}));
})
.into_block();
let source_info = builder.source_info(fn_end);
builder.cfg.terminate(return_block, source_info, TerminatorKind::Return);
builder.build_drop_trees();
return_block.unit()
}));
});
let mut body = builder.finish();
@ -579,7 +584,7 @@ fn construct_const<'a, 'tcx>(
Builder::new(thir, infcx, def, hir_id, span, 0, const_ty, const_ty_span, None);
let mut block = START_BLOCK;
unpack!(block = builder.expr_into_dest(Place::return_place(), block, expr));
block = builder.expr_into_dest(Place::return_place(), block, expr).into_block();
let source_info = builder.source_info(span);
builder.cfg.terminate(block, source_info, TerminatorKind::Return);
@ -961,7 +966,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
Some((Some(&place), span)),
);
let place_builder = PlaceBuilder::from(local);
unpack!(block = self.place_into_pattern(block, pat, place_builder, false));
block = self.place_into_pattern(block, pat, place_builder, false).into_block();
}
}
self.source_scope = original_source_scope;

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@ -510,12 +510,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let target = self.cfg.start_new_block();
let source_info = self.source_info(span);
self.cfg.terminate(
unpack!(normal_block),
normal_block.into_block(),
source_info,
TerminatorKind::Goto { target },
);
self.cfg.terminate(
unpack!(exit_block),
exit_block.into_block(),
source_info,
TerminatorKind::Goto { target },
);
@ -552,14 +552,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let scope = IfThenScope { region_scope, else_drops: DropTree::new() };
let previous_scope = mem::replace(&mut self.scopes.if_then_scope, Some(scope));
let then_block = unpack!(f(self));
let then_block = f(self).into_block();
let if_then_scope = mem::replace(&mut self.scopes.if_then_scope, previous_scope).unwrap();
assert!(if_then_scope.region_scope == region_scope);
let else_block = self
.build_exit_tree(if_then_scope.else_drops, region_scope, span, None)
.map_or_else(|| self.cfg.start_new_block(), |else_block_and| unpack!(else_block_and));
let else_block =
self.build_exit_tree(if_then_scope.else_drops, region_scope, span, None).map_or_else(
|| self.cfg.start_new_block(),
|else_block_and| else_block_and.into_block(),
);
(then_block, else_block)
}
@ -585,7 +587,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
self.push_scope(region_scope);
let mut block;
let rv = unpack!(block = f(self));
unpack!(block = self.pop_scope(region_scope, block));
block = self.pop_scope(region_scope, block).into_block();
self.source_scope = source_scope;
debug!(?block);
block.and(rv)
@ -657,7 +659,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
(Some(destination), Some(value)) => {
debug!("stmt_expr Break val block_context.push(SubExpr)");
self.block_context.push(BlockFrame::SubExpr);
unpack!(block = self.expr_into_dest(destination, block, value));
block = self.expr_into_dest(destination, block, value).into_block();
self.block_context.pop();
}
(Some(destination), None) => {
@ -838,7 +840,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let unwind_to = if needs_cleanup { self.diverge_cleanup() } else { DropIdx::MAX };
let scope = self.scopes.scopes.last().expect("leave_top_scope called with no scopes");
unpack!(build_scope_drops(
build_scope_drops(
&mut self.cfg,
&mut self.scopes.unwind_drops,
scope,
@ -846,7 +848,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
unwind_to,
is_coroutine && needs_cleanup,
self.arg_count,
))
)
.into_block()
}
/// Possibly creates a new source scope if `current_root` and `parent_root`