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fix branch subsumption bug (#1840, #1841)

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Mark
2023-06-24 10:59:29 -06:00
parent 2ec45b7413
commit 9f209dadd9
3 changed files with 116 additions and 72 deletions
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154
src/debray_allocator.rs
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@@ -14,6 +14,7 @@ use indexmap::IndexMap;
use std::cell::Cell;
use std::collections::VecDeque;
use std::ops::{Deref, DerefMut};
pub type BranchHits = IndexMap<usize, BitVec, FxBuildHasher>; // key: var_num, value: branch arm occurrences.
@@ -41,24 +42,51 @@ impl BranchOccurrences {
}
#[derive(Debug)]
pub(crate) struct DebrayAllocator {
pub(crate) var_data: VarData, // var_data replaces bindings.
pub(crate) branch_stack: Vec<BranchOccurrences>,
pub(crate) in_tail_position: bool,
// bindings: IndexMap<usize, VarWitness, FxBuildHasher>, // VarNum -> VarWitness
arg_c: usize,
temp_lb: usize,
perm_lb: usize,
arity: usize, // 0 if not at head.
shallow_temp_mappings: IndexMap<usize, usize, FxBuildHasher>,
in_use: BitSet<usize>, // deep and non-var allocations
temp_free_list: Vec<usize>,
perm_free_list: VecDeque<(usize, usize)>, // chunk_num, var_num
pub(crate) struct BranchStack {
stack: Vec<BranchOccurrences>,
}
impl DebrayAllocator {
impl Deref for BranchStack {
type Target = Vec<BranchOccurrences>;
#[inline]
fn deref(&self) -> &Self::Target {
&self.stack
}
}
impl DerefMut for BranchStack {
#[inline]
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.stack
}
}
impl BranchStack {
fn branch_subsumes(&self, branch: &BranchDesignator, sub_branch: &BranchDesignator) -> bool {
if branch.branch_stack_num < sub_branch.branch_stack_num {
if branch.branch_stack_num == 0 {
true
} else {
let idx = branch.branch_stack_num - 1;
self[idx].current_branch == branch.branch_num
}
} else {
branch == sub_branch
}
}
fn safety_unneeded_in_branch(&self, safety: &VarSafetyStatus, branch: &BranchDesignator) -> bool {
match safety {
VarSafetyStatus::Needed => false,
VarSafetyStatus::LocallyUnneeded(planter_branch) =>
self.branch_subsumes(planter_branch, branch),
VarSafetyStatus::GloballyUnneeded => true,
}
}
pub(crate) fn add_branch_occurrence(&mut self, var_num: usize) {
if let Some(occurrences) = self.branch_stack.last_mut() {
if let Some(occurrences) = self.last_mut() {
debug_assert!(occurrences.current_branch < occurrences.num_branches);
let num_branches = occurrences.num_branches;
@@ -72,32 +100,70 @@ impl DebrayAllocator {
}
pub(crate) fn add_branch_stack(&mut self, num_branches: usize) {
self.branch_stack.push(BranchOccurrences::new(num_branches));
self.push(BranchOccurrences::new(num_branches));
}
pub(crate) fn current_branch_designator(&self) -> BranchDesignator {
let num_branches = self.branch_stack.len();
let current_branch = self.branch_stack.last()
let branch_stack_num = self.len();
let branch_num = self.last()
.map(|occurrences| occurrences.current_branch)
.unwrap_or(0);
BranchDesignator((num_branches, current_branch))
BranchDesignator { branch_stack_num, branch_num }
}
pub(crate) fn add_branch(&mut self) {
let branch_designator = self.current_branch_designator();
let branch_occurrences = self.branch_stack.last_mut().unwrap();
#[inline]
pub(crate) fn incr_current_branch(&mut self) {
let branch_occurrences = self.last_mut().unwrap();
branch_occurrences.current_branch += 1;
}
for var_num in branch_occurrences.subsumed_hits.drain(..) {
#[inline]
pub(crate) fn drain_branches(&mut self, depth: usize) -> std::vec::Drain<BranchOccurrences> {
let start_idx = self.len() - depth;
self.drain(start_idx ..)
}
}
#[derive(Debug)]
pub(crate) struct DebrayAllocator {
pub(crate) var_data: VarData, // var_data replaces bindings.
pub(crate) branch_stack: BranchStack,
pub(crate) in_tail_position: bool,
arg_c: usize,
temp_lb: usize,
perm_lb: usize,
arity: usize, // 0 if not at head.
shallow_temp_mappings: IndexMap<usize, usize, FxBuildHasher>,
in_use: BitSet<usize>, // deep and non-var allocations
temp_free_list: Vec<usize>,
perm_free_list: VecDeque<(usize, usize)>, // chunk_num, var_num
}
impl DebrayAllocator {
pub(crate) fn add_branch(&mut self) {
let branch_designator = self.branch_stack.current_branch_designator();
let subsumed_hits = {
let branch_occurrences = self.branch_stack.last_mut().unwrap();
std::mem::replace(
&mut branch_occurrences.subsumed_hits,
SubsumedBranchHits::with_hasher(FxBuildHasher::default()),
)
};
for var_num in subsumed_hits {
match &mut self.var_data.records[var_num].allocation {
VarAlloc::Perm(_, ref mut allocation) => {
match allocation {
PermVarAllocation::Done { shallow_safety, deep_safety, .. } => {
if !shallow_safety.is_unneeded(branch_designator) {
if !self.branch_stack.safety_unneeded_in_branch(shallow_safety, &branch_designator) {
let branch_occurrences = self.branch_stack.last_mut().unwrap();
branch_occurrences.shallow_safety.insert(var_num);
}
if !deep_safety.is_unneeded(branch_designator) {
if !self.branch_stack.safety_unneeded_in_branch(deep_safety, &branch_designator) {
let branch_occurrences = self.branch_stack.last_mut().unwrap();
branch_occurrences.deep_safety.insert(var_num);
}
}
@@ -113,20 +179,8 @@ impl DebrayAllocator {
}
}
#[inline]
pub(crate) fn incr_current_branch(&mut self) {
let branch_occurrences = self.branch_stack.last_mut().unwrap();
branch_occurrences.current_branch += 1;
}
#[inline]
pub(crate) fn drain_branches(&mut self, depth: usize) -> std::vec::Drain<BranchOccurrences> {
let start_idx = self.branch_stack.len() - depth;
self.branch_stack.drain(start_idx ..)
}
pub(crate) fn pop_branch(&mut self, depth: usize, subsumed_hits: SubsumedBranchHits) {
let removed_branches = self.drain_branches(depth);
let removed_branches = self.branch_stack.drain_branches(depth);
let (deep_safety, shallow_safety) = removed_branches
.into_iter()
@@ -138,7 +192,7 @@ impl DebrayAllocator {
(deep_safety, shallow_safety)
});
let branch_designator = self.current_branch_designator();
let branch_designator = self.branch_stack.current_branch_designator();
let (deep_safety, shallow_safety) = match self.branch_stack.last_mut() {
Some(latest_branch) => {
@@ -176,7 +230,7 @@ impl DebrayAllocator {
if self.branch_stack.len() > 0 {
for var_num in subsumed_hits {
self.add_branch_occurrence(var_num);
self.branch_stack.add_branch_occurrence(var_num);
}
}
}
@@ -452,7 +506,7 @@ impl DebrayAllocator {
}
pub(crate) fn mark_safe_var_unconditionally(&mut self, var_num: usize) {
let branch_designator = self.current_branch_designator();
let branch_designator = self.branch_stack.current_branch_designator();
match &mut self.var_data.records[var_num].allocation {
VarAlloc::Perm(_, PermVarAllocation::Done { deep_safety, shallow_safety, .. }) => {
@@ -467,7 +521,7 @@ impl DebrayAllocator {
}
fn mark_safe_var(&mut self, var_num: usize, lvl: Level, term_loc: GenContext) {
let branch_designator = self.current_branch_designator();
let branch_designator = self.branch_stack.current_branch_designator();
match &mut self.var_data.records[var_num].allocation {
VarAlloc::Perm(_, PermVarAllocation::Done { deep_safety, shallow_safety, .. }) => {
@@ -503,11 +557,11 @@ impl DebrayAllocator {
r: RegType,
arg_c: usize,
) -> Instruction {
let branch_designator = self.current_branch_designator();
let branch_designator = self.branch_stack.current_branch_designator();
match &mut self.var_data.records[var_num].allocation {
VarAlloc::Perm(_, PermVarAllocation::Done { ref mut shallow_safety, .. }) => {
if !self.in_tail_position || shallow_safety.is_unneeded(branch_designator) {
if !self.in_tail_position || self.branch_stack.safety_unneeded_in_branch(shallow_safety, &branch_designator) {
Target::argument_to_value(r, arg_c)
} else {
*shallow_safety = VarSafetyStatus::unneeded(branch_designator);
@@ -515,7 +569,7 @@ impl DebrayAllocator {
}
}
VarAlloc::Temp { ref mut safety, .. } => {
if safety.is_unneeded(branch_designator) {
if self.branch_stack.safety_unneeded_in_branch(safety, &branch_designator) {
Target::argument_to_value(r, arg_c)
} else {
*safety = VarSafetyStatus::GloballyUnneeded;
@@ -533,11 +587,11 @@ impl DebrayAllocator {
var_num: usize,
r: RegType,
) -> Instruction {
let branch_designator = self.current_branch_designator();
let branch_designator = self.branch_stack.current_branch_designator();
match &mut self.var_data.records[var_num].allocation {
VarAlloc::Perm(_, PermVarAllocation::Done { ref mut deep_safety, .. }) => {
if deep_safety.is_unneeded(branch_designator) {
if self.branch_stack.safety_unneeded_in_branch(deep_safety, &branch_designator) {
Target::subterm_to_value(r)
} else {
*deep_safety = VarSafetyStatus::unneeded(branch_designator);
@@ -545,7 +599,7 @@ impl DebrayAllocator {
}
}
VarAlloc::Temp { ref mut safety, .. } => {
if safety.is_unneeded(branch_designator) {
if self.branch_stack.safety_unneeded_in_branch(safety, &branch_designator) {
Target::subterm_to_value(r)
} else {
*safety = VarSafetyStatus::unneeded(branch_designator);
@@ -572,7 +626,7 @@ impl Allocator for DebrayAllocator {
in_use: BitSet::default(),
temp_free_list: vec![],
perm_free_list: VecDeque::new(),
branch_stack: vec![],
branch_stack: BranchStack { stack: vec![] }
}
}
@@ -720,7 +774,7 @@ impl Allocator for DebrayAllocator {
if !r.is_perm() {
self.shallow_temp_mappings.insert(o, var_num);
} else if r.is_perm() && is_new_var {
self.add_branch_occurrence(var_num);
self.branch_stack.add_branch_occurrence(var_num);
}
let record = &mut self.var_data.records[var_num];