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folkertdevfolkertdev
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refactor break_scope 
1 parent ddfb32b commit 0a48c4c

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2 files changed

+155
-169
lines changed

2 files changed

+155
-169
lines changed

‎compiler/rustc_mir_build/src/builder/expr/stmt.rs

+3-6
Original file line numberDiff line numberDiff line change
@@ -92,12 +92,9 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
9292
ExprKind::Break { label, value } => {
9393
this.break_scope(block, value, BreakableTarget::Break(label), source_info)
9494
}
95-
ExprKind::ConstContinue { label, value } => this.break_scope(
96-
block,
97-
Some(value),
98-
BreakableTarget::ConstContinue(label),
99-
source_info,
100-
),
95+
ExprKind::ConstContinue { label, value } => {
96+
this.break_const_continuable_scope(block, value, label, source_info)
97+
}
10198
ExprKind::Return { value } => {
10299
this.break_scope(block, value, BreakableTarget::Return, source_info)
103100
}

‎compiler/rustc_mir_build/src/builder/scope.rs

+152-163
Original file line numberDiff line numberDiff line change
@@ -206,7 +206,6 @@ struct IfThenScope {
206206
pub(crate) enum BreakableTarget {
207207
Continue(region::Scope),
208208
Break(region::Scope),
209-
ConstContinue(region::Scope),
210209
Return,
211210
}
212211

@@ -750,168 +749,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
750749
let break_index = get_scope_index(scope);
751750
(break_index, None)
752751
}
753-
BreakableTarget::ConstContinue(scope) => {
754-
let Some(value) = value else {
755-
span_bug!(span, "#[const_continue] must break with a value")
756-
};
757-
758-
// A break can only break out of a scope, so the value should be a scope
759-
let rustc_middle::thir::ExprKind::Scope { value, .. } = self.thir[value].kind
760-
else {
761-
span_bug!(span, "break value must be a scope")
762-
};
763-
764-
let break_index = self
765-
.scopes
766-
.const_continuable_scopes
767-
.iter()
768-
.rposition(|const_continuable_scope| {
769-
const_continuable_scope.region_scope == scope
770-
})
771-
.unwrap_or_else(|| {
772-
span_bug!(span, "no enclosing const-continuable scope found")
773-
});
774-
775-
let scope = &self.scopes.const_continuable_scopes[break_index];
776-
777-
let state_ty = self.local_decls[scope.state_place.as_local().unwrap()].ty;
778-
let discriminant_ty = match state_ty {
779-
ty if ty.is_enum() => ty.discriminant_ty(self.tcx),
780-
ty if ty.is_integral() => ty,
781-
_ => todo!(),
782-
};
783-
784-
let rvalue = match state_ty {
785-
ty if ty.is_enum() => Rvalue::Discriminant(scope.state_place),
786-
ty if ty.is_integral() => Rvalue::Use(Operand::Copy(scope.state_place)),
787-
_ => todo!(),
788-
};
789-
790-
// the PatCtxt is normally used in pattern exhaustiveness checking, but reused here
791-
// because it performs normalization and const evaluation.
792-
let dropless_arena = rustc_arena::DroplessArena::default();
793-
let typeck_results = self.tcx.typeck(self.def_id);
794-
let cx = RustcPatCtxt {
795-
tcx: self.tcx,
796-
typeck_results,
797-
module: self.tcx.parent_module(self.hir_id).to_def_id(),
798-
// FIXME(#132279): We're in a body, should handle opaques.
799-
typing_env: rustc_middle::ty::TypingEnv::non_body_analysis(
800-
self.tcx,
801-
self.def_id,
802-
),
803-
dropless_arena: &dropless_arena,
804-
match_lint_level: self.hir_id,
805-
whole_match_span: Some(rustc_span::Span::default()),
806-
scrut_span: rustc_span::Span::default(),
807-
refutable: true,
808-
known_valid_scrutinee: true,
809-
};
810-
811-
let Some(real_target) =
812-
self.static_pattern_match(&cx, value, &*scope.arms, &scope.built_match_tree)
813-
else {
814-
self.tcx.dcx().emit_fatal(ConstContinueUnknownJumpTarget { span })
815-
};
816-
817-
self.block_context.push(BlockFrame::SubExpr);
818-
let state_place = scope.state_place;
819-
block = self.expr_into_dest(state_place, block, value).into_block();
820-
self.block_context.pop();
821-
822-
let discr = self.temp(discriminant_ty, source_info.span);
823-
let scope_index = self.scopes.scope_index(
824-
self.scopes.const_continuable_scopes[break_index].region_scope,
825-
span,
826-
);
827-
let scope = &mut self.scopes.const_continuable_scopes[break_index];
828-
self.cfg.push_assign(block, source_info, discr, rvalue);
829-
let drop_and_continue_block = self.cfg.start_new_block();
830-
let imaginary_target = self.cfg.start_new_block();
831-
self.cfg.terminate(
832-
block,
833-
source_info,
834-
TerminatorKind::FalseEdge {
835-
real_target: drop_and_continue_block,
836-
imaginary_target,
837-
},
838-
);
839-
840-
let drops = &mut scope.break_drops;
841-
842-
let drop_idx = self.scopes.scopes[scope_index + 1..]
843-
.iter()
844-
.flat_map(|scope| &scope.drops)
845-
.fold(ROOT_NODE, |drop_idx, &drop| drops.add_drop(drop, drop_idx));
846-
847-
drops.add_entry_point(imaginary_target, drop_idx);
848-
849-
self.cfg.terminate(imaginary_target, source_info, TerminatorKind::UnwindResume);
850-
851-
// FIXME add to drop tree for loop_head
852-
853-
let region_scope = scope.region_scope;
854-
let scope_index = self.scopes.scope_index(region_scope, span);
855-
let mut drops = DropTree::new();
856-
857-
let drop_idx = self.scopes.scopes[scope_index + 1..]
858-
.iter()
859-
.flat_map(|scope| &scope.drops)
860-
.fold(ROOT_NODE, |drop_idx, &drop| drops.add_drop(drop, drop_idx));
861-
862-
drops.add_entry_point(drop_and_continue_block, drop_idx);
863-
864-
// `build_drop_trees` doesn't have access to our source_info, so we
865-
// create a dummy terminator now. `TerminatorKind::UnwindResume` is used
866-
// because MIR type checking will panic if it hasn't been overwritten.
867-
// (See `<ExitScopes as DropTreeBuilder>::link_entry_point`.)
868-
self.cfg.terminate(
869-
drop_and_continue_block,
870-
source_info,
871-
TerminatorKind::UnwindResume,
872-
);
873-
874-
{
875-
let this = &mut *self;
876-
let blocks = drops.build_mir::<ExitScopes>(&mut this.cfg, Some(real_target));
877-
//let is_coroutine = this.coroutine.is_some();
878-
879-
/*// Link the exit drop tree to unwind drop tree.
880-
if drops.drops.iter().any(|drop_node| drop_node.data.kind == DropKind::Value) {
881-
let unwind_target = this.diverge_cleanup_target(region_scope, span);
882-
let mut unwind_indices = IndexVec::from_elem_n(unwind_target, 1);
883-
for (drop_idx, drop_node) in drops.drops.iter_enumerated().skip(1) {
884-
match drop_node.data.kind {
885-
DropKind::Storage | DropKind::ForLint => {
886-
if is_coroutine {
887-
let unwind_drop = this.scopes.unwind_drops.add_drop(
888-
drop_node.data,
889-
unwind_indices[drop_node.next],
890-
);
891-
unwind_indices.push(unwind_drop);
892-
} else {
893-
unwind_indices.push(unwind_indices[drop_node.next]);
894-
}
895-
}
896-
DropKind::Value => {
897-
let unwind_drop = this
898-
.scopes
899-
.unwind_drops
900-
.add_drop(drop_node.data, unwind_indices[drop_node.next]);
901-
this.scopes.unwind_drops.add_entry_point(
902-
blocks[drop_idx].unwrap(),
903-
unwind_indices[drop_node.next],
904-
);
905-
unwind_indices.push(unwind_drop);
906-
}
907-
}
908-
}
909-
}*/
910-
blocks[ROOT_NODE].map(BasicBlock::unit)
911-
};
912-
913-
return self.cfg.start_new_block().unit();
914-
}
915752
};
916753

917754
match (destination, value) {
@@ -972,6 +809,158 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
972809
self.cfg.start_new_block().unit()
973810
}
974811

812+
/// Sets up the drops for jumping from `block` to `scope`.
813+
pub(crate) fn break_const_continuable_scope(
814+
&mut self,
815+
mut block: BasicBlock,
816+
value: ExprId,
817+
scope: region::Scope,
818+
source_info: SourceInfo,
819+
) -> BlockAnd<()> {
820+
let span = source_info.span;
821+
822+
// A break can only break out of a scope, so the value should be a scope.
823+
let rustc_middle::thir::ExprKind::Scope { value, .. } = self.thir[value].kind else {
824+
span_bug!(span, "break value must be a scope")
825+
};
826+
827+
let break_index = self
828+
.scopes
829+
.const_continuable_scopes
830+
.iter()
831+
.rposition(|const_continuable_scope| const_continuable_scope.region_scope == scope)
832+
.unwrap_or_else(|| span_bug!(span, "no enclosing const-continuable scope found"));
833+
834+
let scope = &self.scopes.const_continuable_scopes[break_index];
835+
836+
let state_ty = self.local_decls[scope.state_place.as_local().unwrap()].ty;
837+
let discriminant_ty = match state_ty {
838+
ty if ty.is_enum() => ty.discriminant_ty(self.tcx),
839+
ty if ty.is_integral() => ty,
840+
_ => todo!(),
841+
};
842+
843+
let rvalue = match state_ty {
844+
ty if ty.is_enum() => Rvalue::Discriminant(scope.state_place),
845+
ty if ty.is_integral() => Rvalue::Use(Operand::Copy(scope.state_place)),
846+
_ => todo!(),
847+
};
848+
849+
// the PatCtxt is normally used in pattern exhaustiveness checking, but reused here
850+
// because it performs normalization and const evaluation.
851+
let dropless_arena = rustc_arena::DroplessArena::default();
852+
let typeck_results = self.tcx.typeck(self.def_id);
853+
let cx = RustcPatCtxt {
854+
tcx: self.tcx,
855+
typeck_results,
856+
module: self.tcx.parent_module(self.hir_id).to_def_id(),
857+
// FIXME(#132279): We're in a body, should handle opaques.
858+
typing_env: rustc_middle::ty::TypingEnv::non_body_analysis(self.tcx, self.def_id),
859+
dropless_arena: &dropless_arena,
860+
match_lint_level: self.hir_id,
861+
whole_match_span: Some(rustc_span::Span::default()),
862+
scrut_span: rustc_span::Span::default(),
863+
refutable: true,
864+
known_valid_scrutinee: true,
865+
};
866+
867+
let Some(real_target) =
868+
self.static_pattern_match(&cx, value, &*scope.arms, &scope.built_match_tree)
869+
else {
870+
self.tcx.dcx().emit_fatal(ConstContinueUnknownJumpTarget { span })
871+
};
872+
873+
self.block_context.push(BlockFrame::SubExpr);
874+
let state_place = scope.state_place;
875+
block = self.expr_into_dest(state_place, block, value).into_block();
876+
self.block_context.pop();
877+
878+
let discr = self.temp(discriminant_ty, source_info.span);
879+
let scope_index = self
880+
.scopes
881+
.scope_index(self.scopes.const_continuable_scopes[break_index].region_scope, span);
882+
let scope = &mut self.scopes.const_continuable_scopes[break_index];
883+
self.cfg.push_assign(block, source_info, discr, rvalue);
884+
let drop_and_continue_block = self.cfg.start_new_block();
885+
let imaginary_target = self.cfg.start_new_block();
886+
self.cfg.terminate(
887+
block,
888+
source_info,
889+
TerminatorKind::FalseEdge { real_target: drop_and_continue_block, imaginary_target },
890+
);
891+
892+
let drops = &mut scope.break_drops;
893+
894+
let drop_idx = self.scopes.scopes[scope_index + 1..]
895+
.iter()
896+
.flat_map(|scope| &scope.drops)
897+
.fold(ROOT_NODE, |drop_idx, &drop| drops.add_drop(drop, drop_idx));
898+
899+
drops.add_entry_point(imaginary_target, drop_idx);
900+
901+
self.cfg.terminate(imaginary_target, source_info, TerminatorKind::UnwindResume);
902+
903+
// FIXME add to drop tree for loop_head
904+
905+
let region_scope = scope.region_scope;
906+
let scope_index = self.scopes.scope_index(region_scope, span);
907+
let mut drops = DropTree::new();
908+
909+
let drop_idx = self.scopes.scopes[scope_index + 1..]
910+
.iter()
911+
.flat_map(|scope| &scope.drops)
912+
.fold(ROOT_NODE, |drop_idx, &drop| drops.add_drop(drop, drop_idx));
913+
914+
drops.add_entry_point(drop_and_continue_block, drop_idx);
915+
916+
// `build_drop_trees` doesn't have access to our source_info, so we
917+
// create a dummy terminator now. `TerminatorKind::UnwindResume` is used
918+
// because MIR type checking will panic if it hasn't been overwritten.
919+
// (See `<ExitScopes as DropTreeBuilder>::link_entry_point`.)
920+
self.cfg.terminate(drop_and_continue_block, source_info, TerminatorKind::UnwindResume);
921+
922+
{
923+
let this = &mut *self;
924+
let blocks = drops.build_mir::<ExitScopes>(&mut this.cfg, Some(real_target));
925+
//let is_coroutine = this.coroutine.is_some();
926+
927+
/*// Link the exit drop tree to unwind drop tree.
928+
if drops.drops.iter().any(|drop_node| drop_node.data.kind == DropKind::Value) {
929+
let unwind_target = this.diverge_cleanup_target(region_scope, span);
930+
let mut unwind_indices = IndexVec::from_elem_n(unwind_target, 1);
931+
for (drop_idx, drop_node) in drops.drops.iter_enumerated().skip(1) {
932+
match drop_node.data.kind {
933+
DropKind::Storage | DropKind::ForLint => {
934+
if is_coroutine {
935+
let unwind_drop = this.scopes.unwind_drops.add_drop(
936+
drop_node.data,
937+
unwind_indices[drop_node.next],
938+
);
939+
unwind_indices.push(unwind_drop);
940+
} else {
941+
unwind_indices.push(unwind_indices[drop_node.next]);
942+
}
943+
}
944+
DropKind::Value => {
945+
let unwind_drop = this
946+
.scopes
947+
.unwind_drops
948+
.add_drop(drop_node.data, unwind_indices[drop_node.next]);
949+
this.scopes.unwind_drops.add_entry_point(
950+
blocks[drop_idx].unwrap(),
951+
unwind_indices[drop_node.next],
952+
);
953+
unwind_indices.push(unwind_drop);
954+
}
955+
}
956+
}
957+
}*/
958+
blocks[ROOT_NODE].map(BasicBlock::unit)
959+
};
960+
961+
return self.cfg.start_new_block().unit();
962+
}
963+
975964
/// Sets up the drops for breaking from `block` due to an `if` condition
976965
/// that turned out to be false.
977966
///

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