305 lines
9.4 KiB
Rust
305 lines
9.4 KiB
Rust
use prolog::ast::*;
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use std::cell::Cell;
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use std::collections::{BTreeMap, BTreeSet, HashMap};
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use std::collections::btree_map::{IntoIter, IterMut, Values};
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use std::mem::swap;
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use std::vec::Vec;
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pub type OccurrenceSet = BTreeSet<(GenContext, usize)>;
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pub type HeapVarDict<'a> = HashMap<&'a Var, Addr>;
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pub type AllocVarDict<'a> = HashMap<&'a Var, VarData>;
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pub struct TempVarData {
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last_term_arity: usize,
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pub use_set: OccurrenceSet,
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pub no_use_set: BTreeSet<usize>,
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pub conflict_set: BTreeSet<usize>
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}
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// labeled with chunk numbers.
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pub enum VarStatus {
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Perm(usize), Temp(usize, TempVarData) // Perm(chunk_num) | Temp(chunk_num, _)
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}
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// Perm: 0 initially, a stack register once processed.
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// Temp: labeled with chunk_num and temp offset (unassigned if 0), arg (0 if unassigned).
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pub enum VarData {
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Perm(usize), Temp(usize, usize, TempVarData)
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}
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impl VarData {
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pub fn as_reg_type(&self) -> RegType {
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match self {
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&VarData::Temp(_, r, _) => RegType::Temp(r),
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&VarData::Perm(r) => RegType::Perm(r)
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}
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}
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}
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impl TempVarData {
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fn new(last_term_arity: usize) -> Self {
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TempVarData {
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last_term_arity: last_term_arity,
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use_set: BTreeSet::new(),
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no_use_set: BTreeSet::new(),
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conflict_set: BTreeSet::new()
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}
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}
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fn uses_reg(&self, reg: usize) -> bool {
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for &(_, nreg) in self.use_set.iter() {
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if reg == nreg {
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return true;
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}
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}
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return false;
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}
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fn populate_conflict_set(&mut self) {
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if self.last_term_arity > 0 {
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let arity = self.last_term_arity;
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let mut conflict_set : BTreeSet<usize> = (1..arity).collect();
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for &(_, reg) in self.use_set.iter() {
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conflict_set.remove(®);
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}
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self.conflict_set = conflict_set;
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}
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}
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}
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type VariableFixture<'a> = (VarStatus, Vec<&'a Cell<VarReg>>);
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pub struct VariableFixtures<'a>(BTreeMap<&'a Var, VariableFixture<'a>>);
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impl<'a> VariableFixtures<'a>
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{
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pub fn new() -> Self {
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VariableFixtures(BTreeMap::new())
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}
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pub fn insert(&mut self, var: &'a Var, vs: VariableFixture<'a>) {
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self.0.insert(var, vs);
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}
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// computes no_use and conflict sets for all temp vars.
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pub fn populate_restricting_sets(&mut self)
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{
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// three stages:
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// 1. move the use sets of each variable to a local HashMap, use_set
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// (iterate mutably, swap mutable refs).
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// 2. drain use_set. For each use set of U, add into the
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// no-use sets of appropriate variables T /= U.
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// 3. Move the use sets back to their original locations in the fixture.
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// Compute the conflict set of u.
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// 1.
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let mut use_sets : HashMap<&'a Var, OccurrenceSet> = HashMap::new();
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for (ref var, &mut (ref mut var_status, _)) in self.iter_mut() {
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if let &mut VarStatus::Temp(_, ref mut var_data) = var_status {
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let mut use_set = OccurrenceSet::new();
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swap(&mut var_data.use_set, &mut use_set);
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use_sets.insert(var, use_set);
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}
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}
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for (u, use_set) in use_sets.drain() {
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// 2.
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for &(term_loc, reg) in use_set.iter() {
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if let GenContext::Last(cn_u) = term_loc {
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for (ref t, &mut (ref mut var_status, _)) in self.iter_mut() {
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if let &mut VarStatus::Temp(cn_t, ref mut t_data) = var_status {
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if cn_u == cn_t && *u != ***t {
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if !t_data.uses_reg(reg) {
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t_data.no_use_set.insert(reg);
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}
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}
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}
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}
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}
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}
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// 3.
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match self.get_mut(u) {
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Some(&mut (VarStatus::Temp(_, ref mut u_data), _)) => {
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u_data.use_set = use_set;
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u_data.populate_conflict_set();
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},
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_ => {}
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};
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}
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}
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fn get_mut(&mut self, u: &'a Var) -> Option<&mut VariableFixture<'a>> {
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self.0.get_mut(u)
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}
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fn iter_mut(&mut self) -> IterMut<&'a Var, VariableFixture<'a>> {
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self.0.iter_mut()
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}
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fn record_temp_info(&mut self,
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tvd: &mut TempVarData,
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arg_c: usize,
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term_loc: GenContext)
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{
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match term_loc {
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GenContext::Head | GenContext::Last(_) => {
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tvd.use_set.insert((term_loc, arg_c));
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},
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_ => {}
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};
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}
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pub fn vars_above_threshold(&self, index: usize) -> usize
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{
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let mut var_count = 0;
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for &(ref var_status, _) in self.values() {
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if let &VarStatus::Perm(i) = var_status {
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if i > index {
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var_count += 1;
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}
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}
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}
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var_count
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}
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pub fn mark_vars_in_chunk(&mut self,
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term: &'a Term,
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last_term_arity: usize,
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chunk_num: usize,
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term_loc: GenContext)
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{
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let mut arg_c = 1;
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for term_ref in term.breadth_first_iter() {
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if let TermRef::Var(lvl, cell, var) = term_ref {
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let mut status = self.0.remove(var)
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.unwrap_or((VarStatus::Temp(chunk_num, TempVarData::new(last_term_arity)),
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Vec::new()));
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status.1.push(cell);
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match status.0 {
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VarStatus::Temp(cn, ref mut tvd) if cn == chunk_num => {
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if let Level::Shallow = lvl {
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self.record_temp_info(tvd, arg_c, term_loc);
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}
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},
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_ => status.0 = VarStatus::Perm(chunk_num)
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};
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self.0.insert(var, status);
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}
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if let Level::Shallow = term_ref.level() {
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arg_c += 1;
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}
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}
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}
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pub fn into_iter(self) -> IntoIter<&'a Var, VariableFixture<'a>> {
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self.0.into_iter()
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}
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fn values(&self) -> Values<&'a Var, VariableFixture<'a>> {
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self.0.values()
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}
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pub fn set_perm_vals(&self, has_deep_cuts: bool)
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{
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let mut values_vec : Vec<_> = self.values()
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.filter_map(|ref v| {
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match &v.0 {
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&VarStatus::Perm(i) => Some((i, &v.1)),
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_ => None
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}
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})
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.collect();
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values_vec.sort_by_key(|ref v| v.0);
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let offset = has_deep_cuts as usize;
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for (i, (_, cells)) in values_vec.into_iter().rev().enumerate() {
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for cell in cells {
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cell.set(VarReg::Norm(RegType::Perm(i + 1 + offset)));
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}
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}
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}
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fn mark_unsafe_vars(&self, unsafe_vars: &mut HashMap<RegType, bool>, query: &mut CompiledQuery)
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{
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for query_instr in query.iter_mut() {
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match query_instr {
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&mut QueryInstruction::PutValue(RegType::Perm(i), arg) =>
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if let Some(found) = unsafe_vars.get_mut(&RegType::Perm(i)) {
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if !*found {
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*found = true;
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*query_instr = QueryInstruction::PutUnsafeValue(i, arg);
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}
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},
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&mut QueryInstruction::SetVariable(reg)
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| &mut QueryInstruction::PutVariable(reg, _) =>
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if let Some(found) = unsafe_vars.get_mut(®) {
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*found = true;
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},
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&mut QueryInstruction::SetValue(reg) =>
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if let Some(found) = unsafe_vars.get_mut(®) {
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if !*found {
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*found = true;
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*query_instr = QueryInstruction::SetLocalValue(reg);
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}
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},
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_ => {}
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};
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}
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}
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fn record_unsafe_vars(&self, unsafe_vars: &mut HashMap<RegType, bool>) {
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for &(_, ref cb) in self.values() {
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match cb.first() {
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Some(index) => {
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unsafe_vars.insert(index.get().norm(), false);
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},
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None => {}
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};
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}
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}
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fn mark_head_vars_as_safe(&self, head: &Term, unsafe_vars: &mut HashMap<RegType, bool>)
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{
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for term_ref in head.breadth_first_iter() {
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match term_ref {
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TermRef::Var(_, cell, _) => {
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unsafe_vars.remove(&cell.get().norm());
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},
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_ => {}
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};
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}
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}
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pub fn mark_unsafe_vars_in_query(&self, query: &mut CompiledQuery) {
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let mut unsafe_vars = HashMap::new();
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self.record_unsafe_vars(&mut unsafe_vars);
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self.mark_unsafe_vars(&mut unsafe_vars, query);
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}
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pub fn mark_unsafe_vars_in_rule(&self, head: &Term, query: &mut CompiledQuery)
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{
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let mut unsafe_vars = HashMap::new();
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self.record_unsafe_vars(&mut unsafe_vars);
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self.mark_head_vars_as_safe(head, &mut unsafe_vars);
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self.mark_unsafe_vars(&mut unsafe_vars, query);
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}
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}
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