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mark cells that are about to be iterated in the stackful iterator (#1418)

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This commit is contained in:
Mark Thom
2022-04-12 22:51:20 -06:00
parent d644a3996e
commit d8cf0f320d
1 changed files with 72 additions and 43 deletions
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117
src/heap_iter.rs
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@@ -10,6 +10,49 @@ use modular_bitfield::prelude::*;
use std::ops::Deref;
use std::vec::Vec;
#[derive(BitfieldSpecifier, Clone, Copy, Debug, PartialEq, Eq)]
#[bits = 2]
enum IterStackLocTag {
Iterable,
Marked,
PendingMark,
}
#[bitfield]
#[repr(u64)]
#[derive(Clone, Copy, Debug)]
pub struct IterStackLoc {
value: B62,
tag: IterStackLocTag,
}
impl IterStackLoc {
#[inline]
pub fn iterable_heap_loc(h: usize) -> Self {
IterStackLoc::new().with_tag(IterStackLocTag::Iterable).with_value(h as u64)
}
#[inline]
pub fn mark_heap_loc(h: usize) -> Self {
IterStackLoc::new().with_tag(IterStackLocTag::Marked).with_value(h as u64)
}
#[inline]
pub fn pending_mark_heap_loc(h: usize) -> Self {
IterStackLoc::new().with_tag(IterStackLocTag::PendingMark).with_value(h as u64)
}
#[inline]
pub fn is_marked(self) -> bool {
self.tag() == IterStackLocTag::Marked
}
#[inline]
pub fn is_pending_mark(self) -> bool {
self.tag() == IterStackLocTag::PendingMark
}
}
#[inline]
fn forward_if_referent_marked(heap: &mut [HeapCellValue], h: usize) {
read_heap_cell!(heap[h],
@@ -26,26 +69,6 @@ fn forward_if_referent_marked(heap: &mut [HeapCellValue], h: usize) {
)
}
#[bitfield]
#[repr(u64)]
#[derive(Clone, Copy, Debug)]
pub struct IterStackLoc {
value: B63,
m: bool,
}
impl IterStackLoc {
#[inline]
pub fn iterable_heap_loc(h: usize) -> Self {
IterStackLoc::new().with_m(false).with_value(h as u64)
}
#[inline]
pub fn mark_heap_loc(h: usize) -> Self {
IterStackLoc::new().with_m(true).with_value(h as u64)
}
}
#[derive(Debug)]
pub struct StackfulPreOrderHeapIter<'a> {
pub heap: &'a mut Vec<HeapCellValue>,
@@ -87,7 +110,7 @@ impl<'a> StackfulPreOrderHeapIter<'a> {
#[inline]
pub fn stack_last(&self) -> Option<usize> {
for h in self.stack.iter().rev() {
let is_readable_marked = h.m();
let is_readable_marked = h.is_marked();
let h = h.value() as usize;
let cell = self.heap[h];
@@ -111,7 +134,7 @@ impl<'a> StackfulPreOrderHeapIter<'a> {
#[inline]
pub fn pop_stack(&mut self) -> Option<HeapCellValue> {
while let Some(h) = self.stack.pop() {
let is_readable_marked = h.m();
let is_readable_marked = h.is_marked();
let h = h.value() as usize;
self.h = h;
@@ -139,7 +162,17 @@ impl<'a> StackfulPreOrderHeapIter<'a> {
fn follow(&mut self) -> Option<HeapCellValue> {
while let Some(h) = self.stack.pop() {
let is_readable_marked = h.m();
if h.is_pending_mark() {
let h = h.value() as usize;
self.push_if_unmarked(h);
self.stack.push(IterStackLoc::mark_heap_loc(h));
forward_if_referent_marked(&mut self.heap, h);
continue;
}
let is_readable_marked = h.is_marked();
let h = h.value() as usize;
self.h = h;
@@ -155,22 +188,21 @@ impl<'a> StackfulPreOrderHeapIter<'a> {
}
read_heap_cell!(*cell,
(HeapCellValueTag::Str, vh) => {
self.stack.push(IterStackLoc::iterable_heap_loc(vh));
(HeapCellValueTag::Str | HeapCellValueTag::PStrLoc, vh) => {
self.push_if_unmarked(vh);
self.stack.push(IterStackLoc::mark_heap_loc(vh));
}
(HeapCellValueTag::Lis, vh) => {
self.push_if_unmarked(vh);
self.push_if_unmarked(vh + 1);
self.stack.push(IterStackLoc::mark_heap_loc(vh + 1));
forward_if_referent_marked(&mut self.heap, vh + 1);
self.stack.push(IterStackLoc::pending_mark_heap_loc(vh + 1));
self.stack.push(IterStackLoc::mark_heap_loc(vh));
forward_if_referent_marked(&mut self.heap, vh);
return Some(self.heap[h]);
}
(HeapCellValueTag::AttrVar | HeapCellValueTag::PStrLoc | HeapCellValueTag::Var, vh) => {
(HeapCellValueTag::AttrVar | HeapCellValueTag::Var, vh) => {
self.push_if_unmarked(vh);
self.stack.push(IterStackLoc::mark_heap_loc(vh));
forward_if_referent_marked(&mut self.heap, vh);
@@ -190,17 +222,14 @@ impl<'a> StackfulPreOrderHeapIter<'a> {
return Some(self.heap[h]);
}
(HeapCellValueTag::Atom, (_name, arity)) => {
for h in (h + 2 .. h + arity + 1).rev() {
self.stack.push(IterStackLoc::pending_mark_heap_loc(h));
}
if arity > 0 {
self.push_if_unmarked(h);
for h in h + 1 .. h + arity + 1 {
self.push_if_unmarked(h);
}
}
for h in (h + 1 .. h + arity + 1).rev() {
self.stack.push(IterStackLoc::mark_heap_loc(h));
forward_if_referent_marked(&mut self.heap, h);
self.push_if_unmarked(h+1);
self.stack.push(IterStackLoc::mark_heap_loc(h+1));
forward_if_referent_marked(&mut self.heap, h+1);
}
return Some(self.heap[h]);
@@ -1313,7 +1342,7 @@ mod tests {
.extend(functor!(f_atom, [atom(a_atom), atom(b_atom)]));
{
let mut iter = StackfulPreOrderHeapIter::new(&mut wam.machine_st.heap, heap_loc_as_cell!(0));
let mut iter = StackfulPreOrderHeapIter::new(&mut wam.machine_st.heap, str_loc_as_cell!(0));
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
@@ -1344,7 +1373,7 @@ mod tests {
));
for _ in 0..20 {
let mut iter = StackfulPreOrderHeapIter::new(&mut wam.machine_st.heap, heap_loc_as_cell!(0));
let mut iter = StackfulPreOrderHeapIter::new(&mut wam.machine_st.heap, str_loc_as_cell!(0));
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
@@ -1830,7 +1859,7 @@ mod tests {
.extend(functor!(f_atom, [atom(a_atom), atom(b_atom)]));
{
let mut iter = stackful_post_order_iter(&mut wam.machine_st.heap, heap_loc_as_cell!(0));
let mut iter = stackful_post_order_iter(&mut wam.machine_st.heap, str_loc_as_cell!(0));
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),
@@ -1861,7 +1890,7 @@ mod tests {
));
for _ in 0..20 { // 0000 {
let mut iter = stackful_post_order_iter(&mut wam.machine_st.heap, heap_loc_as_cell!(0));
let mut iter = stackful_post_order_iter(&mut wam.machine_st.heap, str_loc_as_cell!(0));
assert_eq!(
unmark_cell_bits!(iter.next().unwrap()),