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Fix a bug with caching ids in the HIR lowering with nested lowered nodes

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Blocks #30884
This commit is contained in:
Nick Cameron 2016-01-20 15:34:52 +13:00
parent 08886499cf
commit 7ffd408d86
1 changed files with 61 additions and 52 deletions
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113
src/librustc_front/lowering.rs
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@ -87,7 +87,8 @@ pub struct LoweringContext<'a> {
cached_id: Cell<u32>,
// Keep track of gensym'ed idents.
gensym_cache: RefCell<HashMap<(NodeId, &'static str), hir::Ident>>,
// A copy of cached_id, but is also set to an id while it is being cached.
// A copy of cached_id, but is also set to an id while a node is lowered for
// the first time.
gensym_key: Cell<u32>,
}
@ -114,32 +115,79 @@ impl<'a, 'hir> LoweringContext<'a> {
}
fn next_id(&self) -> NodeId {
let cached = self.cached_id.get();
if cached == 0 {
let cached_id = self.cached_id.get();
if cached_id == 0 {
return self.id_assigner.next_node_id();
}
self.cached_id.set(cached + 1);
cached
self.cached_id.set(cached_id + 1);
cached_id
}
fn str_to_ident(&self, s: &'static str) -> hir::Ident {
let cached_id = self.gensym_key.get();
if cached_id == 0 {
let gensym_key = self.gensym_key.get();
if gensym_key == 0 {
return hir::Ident::from_name(token::gensym(s));
}
let cached = self.gensym_cache.borrow().contains_key(&(cached_id, s));
let cached = self.gensym_cache.borrow().contains_key(&(gensym_key, s));
if cached {
self.gensym_cache.borrow()[&(cached_id, s)]
self.gensym_cache.borrow()[&(gensym_key, s)]
} else {
let result = hir::Ident::from_name(token::gensym(s));
self.gensym_cache.borrow_mut().insert((cached_id, s), result);
self.gensym_cache.borrow_mut().insert((gensym_key, s), result);
result
}
}
}
// Utility fn for setting and unsetting the cached id.
fn cache_ids<'a, OP, R>(lctx: &LoweringContext, expr_id: NodeId, op: OP) -> R
where OP: FnOnce(&LoweringContext) -> R
{
// Only reset the id if it was previously 0, i.e., was not cached.
// If it was cached, we are in a nested node, but our id count will
// still count towards the parent's count.
let reset_cached_id = lctx.cached_id.get() == 0;
// We always reset gensym_key so that if we use the same name in a nested
// node and after that node, they get different values.
let old_gensym_key = lctx.gensym_key.get();
{
let id_cache: &mut HashMap<_, _> = &mut lctx.id_cache.borrow_mut();
if id_cache.contains_key(&expr_id) {
let cached_id = lctx.cached_id.get();
if cached_id == 0 {
// We're entering a node where we need to track ids, but are not
// yet tracking.
lctx.cached_id.set(id_cache[&expr_id]);
} else {
// We're already tracking - check that the tracked id is the same
// as the expected id.
assert!(cached_id == id_cache[&expr_id], "id mismatch");
}
lctx.gensym_key.set(id_cache[&expr_id]);
} else {
// We've never lowered this node before, remember it for next time.
let next_id = lctx.id_assigner.peek_node_id();
id_cache.insert(expr_id, next_id);
lctx.gensym_key.set(next_id);
// self.cached_id is not set when we lower a node for the first time,
// only on re-lowering.
}
}
let result = op(lctx);
if reset_cached_id {
lctx.cached_id.set(0);
}
lctx.gensym_key.set(old_gensym_key);
result
}
pub fn lower_ident(_lctx: &LoweringContext, ident: Ident) -> hir::Ident {
hir::Ident {
name: mtwt::resolve(ident),
@ -918,47 +966,6 @@ pub fn lower_pat(lctx: &LoweringContext, p: &Pat) -> P<hir::Pat> {
})
}
// Utility fn for setting and unsetting the cached id.
fn cache_ids<'a, OP, R>(lctx: &LoweringContext, expr_id: NodeId, op: OP) -> R
where OP: FnOnce(&LoweringContext) -> R
{
// Only reset the id if it was previously 0, i.e., was not cached.
// If it was cached, we are in a nested node, but our id count will
// still count towards the parent's count.
let reset_cached_id = lctx.cached_id.get() == 0;
{
let id_cache: &mut HashMap<_, _> = &mut lctx.id_cache.borrow_mut();
if id_cache.contains_key(&expr_id) {
let cached_id = lctx.cached_id.get();
if cached_id == 0 {
// We're entering a node where we need to track ids, but are not
// yet tracking.
lctx.cached_id.set(id_cache[&expr_id]);
lctx.gensym_key.set(id_cache[&expr_id]);
} else {
// We're already tracking - check that the tracked id is the same
// as the expected id.
assert!(cached_id == id_cache[&expr_id], "id mismatch");
}
} else {
let next_id = lctx.id_assigner.peek_node_id();
id_cache.insert(expr_id, next_id);
lctx.gensym_key.set(next_id);
}
}
let result = op(lctx);
if reset_cached_id {
lctx.cached_id.set(0);
lctx.gensym_key.set(0);
}
result
}
pub fn lower_expr(lctx: &LoweringContext, e: &Expr) -> P<hir::Expr> {
P(hir::Expr {
id: e.id,
@ -1935,7 +1942,9 @@ mod test {
let ast_while_let = assigner.fold_expr(ast_while_let);
let ast_for = quote_expr!(&cx,
for i in 0..10 {
foo(i);
for j in 0..10 {
foo(i, j);
}
});
let ast_for = assigner.fold_expr(ast_for);
let ast_in = quote_expr!(&cx, in HEAP { foo() });