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Use external stack in borrowck DFS #18255

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Oct 6, 2024
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Use external stack in borrowck DFS #18255

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125 changes: 67 additions & 58 deletions crates/hir-ty/src/mir/borrowck.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -386,82 +386,91 @@ fn ever_initialized_map(
fn dfs(
db: &dyn HirDatabase,
body: &MirBody,
b: BasicBlockId,
l: LocalId,
stack: &mut Vec<BasicBlockId>,
result: &mut ArenaMap<BasicBlockId, ArenaMap<LocalId, bool>>,
) {
let mut is_ever_initialized = result[b][l]; // It must be filled, as we use it as mark for dfs
let block = &body.basic_blocks[b];
for statement in &block.statements {
match &statement.kind {
StatementKind::Assign(p, _) => {
if p.projection.lookup(&body.projection_store).is_empty() && p.local == l {
is_ever_initialized = true;
while let Some(b) = stack.pop() {
let mut is_ever_initialized = result[b][l]; // It must be filled, as we use it as mark for dfs
let block = &body.basic_blocks[b];
for statement in &block.statements {
match &statement.kind {
StatementKind::Assign(p, _) => {
if p.projection.lookup(&body.projection_store).is_empty() && p.local == l {
is_ever_initialized = true;
}
}
}
StatementKind::StorageDead(p) => {
if *p == l {
is_ever_initialized = false;
StatementKind::StorageDead(p) => {
if *p == l {
is_ever_initialized = false;
}
}
StatementKind::Deinit(_)
| StatementKind::FakeRead(_)
| StatementKind::Nop
| StatementKind::StorageLive(_) => (),
}
StatementKind::Deinit(_)
| StatementKind::FakeRead(_)
| StatementKind::Nop
| StatementKind::StorageLive(_) => (),
}
}
let Some(terminator) = &block.terminator else {
never!(
"Terminator should be none only in construction.\nThe body:\n{}",
body.pretty_print(db)
);
return;
};
let mut process = |target, is_ever_initialized| {
if !result[target].contains_idx(l) || !result[target][l] && is_ever_initialized {
result[target].insert(l, is_ever_initialized);
dfs(db, body, target, l, result);
}
};
match &terminator.kind {
TerminatorKind::Goto { target } => process(*target, is_ever_initialized),
TerminatorKind::SwitchInt { targets, .. } => {
targets.all_targets().iter().for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::UnwindResume
| TerminatorKind::Abort
| TerminatorKind::Return
| TerminatorKind::Unreachable => (),
TerminatorKind::Call { target, cleanup, destination, .. } => {
if destination.projection.lookup(&body.projection_store).is_empty()
&& destination.local == l
{
is_ever_initialized = true;
let Some(terminator) = &block.terminator else {
never!(
"Terminator should be none only in construction.\nThe body:\n{}",
body.pretty_print(db)
);
return;
};
let mut process = |target, is_ever_initialized| {
if !result[target].contains_idx(l) || !result[target][l] && is_ever_initialized {
result[target].insert(l, is_ever_initialized);
stack.push(target);
}
};
match &terminator.kind {
TerminatorKind::Goto { target } => process(*target, is_ever_initialized),
TerminatorKind::SwitchInt { targets, .. } => {
targets.all_targets().iter().for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::UnwindResume
| TerminatorKind::Abort
| TerminatorKind::Return
| TerminatorKind::Unreachable => (),
TerminatorKind::Call { target, cleanup, destination, .. } => {
if destination.projection.lookup(&body.projection_store).is_empty()
&& destination.local == l
{
is_ever_initialized = true;
}
target.iter().chain(cleanup).for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::Drop { target, unwind, place: _ } => {
iter::once(target)
.chain(unwind)
.for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::DropAndReplace { .. }
| TerminatorKind::Assert { .. }
| TerminatorKind::Yield { .. }
| TerminatorKind::CoroutineDrop
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. } => {
never!("We don't emit these MIR terminators yet");
}
target.iter().chain(cleanup).for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::Drop { target, unwind, place: _ } => {
iter::once(target).chain(unwind).for_each(|&it| process(it, is_ever_initialized));
}
TerminatorKind::DropAndReplace { .. }
| TerminatorKind::Assert { .. }
| TerminatorKind::Yield { .. }
| TerminatorKind::CoroutineDrop
| TerminatorKind::FalseEdge { .. }
| TerminatorKind::FalseUnwind { .. } => {
never!("We don't emit these MIR terminators yet");
}
}
}
let mut stack = Vec::new();
for &l in &body.param_locals {
result[body.start_block].insert(l, true);
dfs(db, body, body.start_block, l, &mut result);
stack.clear();
stack.push(body.start_block);
dfs(db, body, l, &mut stack, &mut result);
}
for l in body.locals.iter().map(|it| it.0) {
db.unwind_if_cancelled();
if !result[body.start_block].contains_idx(l) {
result[body.start_block].insert(l, false);
dfs(db, body, body.start_block, l, &mut result);
stack.clear();
stack.push(body.start_block);
dfs(db, body, l, &mut stack, &mut result);
}
}
result
Expand Down