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use branch numbers to detect branch subsumption

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This commit is contained in:
Mark Thom
2025-12-09 23:14:24 -08:00
parent 16dc10ee96
commit 9089f9ddb4
6 changed files with 218 additions and 181 deletions
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64
src/debray_allocator.rs
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@@ -1,6 +1,6 @@
use crate::allocator::*;
use crate::codegen::SubsumedBranchHits;
use crate::forms::{GenContext, Level};
use crate::forms::{BranchNumber, GenContext, Level};
use crate::instructions::*;
use crate::machine::disjuncts::VarData;
use crate::parser::ast::*;
@@ -24,24 +24,26 @@ pub struct BranchOccurrences {
pub shallow_safety: BitSet<usize>, // unset means safe, set means unsafe (after the branch merge)
pub deep_safety: BitSet<usize>,
pub num_branches: usize,
pub current_branch: usize,
pub current_branch_idx: usize,
pub current_branch_num: BranchNumber,
pub subsumed_hits: SubsumedBranchHits,
}
impl BranchOccurrences {
fn new(num_branches: usize) -> Self {
fn new(current_branch_num: BranchNumber, num_branches: usize) -> Self {
Self {
hits: BranchHits::with_hasher(FxBuildHasher::default()),
shallow_safety: BitSet::default(),
deep_safety: BitSet::default(),
num_branches,
current_branch: 0,
current_branch_idx: 0,
current_branch_num,
subsumed_hits: SubsumedBranchHits::with_hasher(FxBuildHasher::default()),
}
}
pub(crate) fn add_branch_occurrence(&mut self, var_num: usize) {
debug_assert!(self.current_branch < self.num_branches);
debug_assert!(self.current_branch_idx < self.num_branches);
let num_branches = self.num_branches;
let entry = self
@@ -49,7 +51,7 @@ impl BranchOccurrences {
.entry(var_num)
.or_insert_with(|| BitVec::repeat(false, num_branches));
entry.set(self.current_branch, true);
entry.set(self.current_branch_idx, true);
self.subsumed_hits.insert(var_num);
}
}
@@ -76,19 +78,6 @@ impl DerefMut for BranchStack {
}
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,
@@ -97,7 +86,7 @@ impl BranchStack {
match safety {
VarSafetyStatus::Needed => false,
VarSafetyStatus::LocallyUnneeded(planter_branch) => {
self.branch_subsumes(planter_branch, branch)
planter_branch.branch_num.has_as_subbranch(&branch.branch_num)
}
VarSafetyStatus::GloballyUnneeded => true,
}
@@ -109,27 +98,26 @@ impl BranchStack {
}
}
pub(crate) fn add_branch_stack(&mut self, num_branches: usize) {
self.push(BranchOccurrences::new(num_branches));
pub(crate) fn add_branch_stack(&mut self, branch_num: BranchNumber, num_branches: usize) {
self.push(BranchOccurrences::new(branch_num, num_branches));
}
pub(crate) fn current_branch_designator(&self) -> BranchDesignator {
let branch_stack_num = self.len();
let branch_num = self
.last()
.map(|occurrences| occurrences.current_branch)
.unwrap_or(0);
.map(|occurrences| occurrences.current_branch_num.clone())
.unwrap_or_else(|| BranchNumber::default());
BranchDesignator {
branch_stack_num,
branch_num,
}
}
#[inline]
pub(crate) fn incr_current_branch(&mut self) {
pub(crate) fn incr_current_branch(&mut self, branch_num: BranchNumber) {
let branch_occurrences = self.last_mut().unwrap();
branch_occurrences.current_branch += 1;
branch_occurrences.current_branch_idx += 1;
branch_occurrences.current_branch_num = branch_num;
}
#[inline]
@@ -235,12 +223,12 @@ impl DebrayAllocator {
VarAlloc::Perm(_, allocation) => {
let shallow_safety = VarSafetyStatus::needed_if(
shallow_safety.contains(var_num),
branch_designator,
&branch_designator,
);
let deep_safety = VarSafetyStatus::needed_if(
deep_safety.contains(var_num),
branch_designator,
&branch_designator,
);
if running_count < num_occurrences {
@@ -531,11 +519,11 @@ impl DebrayAllocator {
..
},
) => {
*deep_safety = VarSafetyStatus::unneeded(branch_designator);
*shallow_safety = VarSafetyStatus::unneeded(branch_designator);
*deep_safety = VarSafetyStatus::unneeded(&branch_designator);
*shallow_safety = VarSafetyStatus::unneeded(&branch_designator);
}
VarAlloc::Temp { safety, .. } => {
*safety = VarSafetyStatus::unneeded(branch_designator);
*safety = VarSafetyStatus::unneeded(&branch_designator);
}
_ => {
unreachable!()
@@ -557,8 +545,8 @@ impl DebrayAllocator {
) => {
// GetVariable in head chunk is considered safe.
if lvl == Level::Deep {
*deep_safety = VarSafetyStatus::unneeded(branch_designator);
*shallow_safety = VarSafetyStatus::unneeded(branch_designator);
*deep_safety = VarSafetyStatus::unneeded(&branch_designator);
*shallow_safety = VarSafetyStatus::unneeded(&branch_designator);
} else if term_loc == GenContext::Head {
*shallow_safety = VarSafetyStatus::GloballyUnneeded;
} else if let Some(&temp_var_num) = self.shallow_temp_mappings.get(&self.arg_c) {
@@ -605,7 +593,7 @@ impl DebrayAllocator {
{
Target::argument_to_value(r, arg_c)
} else {
*shallow_safety = VarSafetyStatus::unneeded(branch_designator);
*shallow_safety = VarSafetyStatus::unneeded(&branch_designator);
Target::unsafe_argument_to_value(r, arg_c)
}
}
@@ -640,7 +628,7 @@ impl DebrayAllocator {
{
Target::subterm_to_value(r)
} else {
*deep_safety = VarSafetyStatus::unneeded(branch_designator);
*deep_safety = VarSafetyStatus::unneeded(&branch_designator);
Target::unsafe_subterm_to_value(r)
}
}
@@ -651,7 +639,7 @@ impl DebrayAllocator {
{
Target::subterm_to_value(r)
} else {
*safety = VarSafetyStatus::unneeded(branch_designator);
*safety = VarSafetyStatus::unneeded(&branch_designator);
Target::unsafe_subterm_to_value(r)
}
}