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Remove unnecessary uses of ObligationForest::scratch.

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They don't help performance at all, and just complicate things.
This commit is contained in:
Nicholas Nethercote 2019-09-24 19:00:42 +10:00
parent ea726501e1
commit 22943ee27c
1 changed files with 8 additions and 12 deletions
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20
src/librustc_data_structures/obligation_forest/mod.rs
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@ -151,9 +151,8 @@ pub struct ObligationForest<O: ForestObligation> {
/// comments in `process_obligation` for details.
active_cache: FxHashMap<O::Predicate, usize>,
/// A scratch vector reused in various operations, to avoid allocating new
/// vectors.
scratch: RefCell<Vec<usize>>,
/// A vector reused in compress(), to avoid allocating new vectors.
node_rewrites: RefCell<Vec<usize>>,
obligation_tree_id_generator: ObligationTreeIdGenerator,
@ -275,7 +274,7 @@ impl<O: ForestObligation> ObligationForest<O> {
nodes: vec![],
done_cache: Default::default(),
active_cache: Default::default(),
scratch: RefCell::new(vec![]),
node_rewrites: RefCell::new(vec![]),
obligation_tree_id_generator: (0..).map(ObligationTreeId),
error_cache: Default::default(),
}
@ -472,8 +471,7 @@ impl<O: ForestObligation> ObligationForest<O> {
fn process_cycles<P>(&self, processor: &mut P)
where P: ObligationProcessor<Obligation=O>
{
let mut stack = self.scratch.replace(vec![]);
debug_assert!(stack.is_empty());
let mut stack = vec![];
debug!("process_cycles()");
@ -493,7 +491,6 @@ impl<O: ForestObligation> ObligationForest<O> {
debug!("process_cycles: complete");
debug_assert!(stack.is_empty());
self.scratch.replace(stack);
}
fn find_cycles_from_node<P>(&self, stack: &mut Vec<usize>, processor: &mut P, index: usize)
@ -533,7 +530,7 @@ impl<O: ForestObligation> ObligationForest<O> {
/// Returns a vector of obligations for `p` and all of its
/// ancestors, putting them into the error state in the process.
fn error_at(&self, mut index: usize) -> Vec<O> {
let mut error_stack = self.scratch.replace(vec![]);
let mut error_stack: Vec<usize> = vec![];
let mut trace = vec![];
loop {
@ -562,7 +559,6 @@ impl<O: ForestObligation> ObligationForest<O> {
error_stack.extend(node.dependents.iter());
}
self.scratch.replace(error_stack);
trace
}
@ -617,7 +613,7 @@ impl<O: ForestObligation> ObligationForest<O> {
#[inline(never)]
fn compress(&mut self, do_completed: DoCompleted) -> Option<Vec<O>> {
let nodes_len = self.nodes.len();
let mut node_rewrites: Vec<_> = self.scratch.replace(vec![]);
let mut node_rewrites: Vec<_> = self.node_rewrites.replace(vec![]);
node_rewrites.extend(0..nodes_len);
let mut dead_nodes = 0;
@ -667,7 +663,7 @@ impl<O: ForestObligation> ObligationForest<O> {
// No compression needed.
if dead_nodes == 0 {
node_rewrites.truncate(0);
self.scratch.replace(node_rewrites);
self.node_rewrites.replace(node_rewrites);
return if do_completed == DoCompleted::Yes { Some(vec![]) } else { None };
}
@ -690,7 +686,7 @@ impl<O: ForestObligation> ObligationForest<O> {
self.apply_rewrites(&node_rewrites);
node_rewrites.truncate(0);
self.scratch.replace(node_rewrites);
self.node_rewrites.replace(node_rewrites);
successful
}