--- /dev/null
+use crate::parser::ast::*;
+
+use crate::forms::*;
+use crate::instructions::*;
+use crate::iterators::*;
+
+use indexmap::{IndexMap, IndexSet};
+
+use std::cell::Cell;
+use std::collections::BTreeSet;
+use std::mem::swap;
+use std::rc::Rc;
+use std::vec::Vec;
+
+// labeled with chunk numbers.
+#[derive(Debug)]
+pub(crate) enum VarStatus {
+ Perm(usize),
+ Temp(usize, TempVarData), // Perm(chunk_num) | Temp(chunk_num, _)
+}
+
+pub(crate) type OccurrenceSet = BTreeSet<(GenContext, usize)>;
+
+// Perm: 0 initially, a stack register once processed.
+// Temp: labeled with chunk_num and temp offset (unassigned if 0).
+#[derive(Debug)]
+pub(crate) enum VarData {
+ Perm(usize),
+ Temp(usize, usize, TempVarData),
+}
+
+impl VarData {
+ pub(crate) fn as_reg_type(&self) -> RegType {
+ match self {
+ &VarData::Temp(_, r, _) => RegType::Temp(r),
+ &VarData::Perm(r) => RegType::Perm(r),
+ }
+ }
+}
+
+#[derive(Debug)]
+pub(crate) struct TempVarData {
+ pub(crate) last_term_arity: usize,
+ pub(crate) use_set: OccurrenceSet,
+ pub(crate) no_use_set: BTreeSet<usize>,
+ pub(crate) conflict_set: BTreeSet<usize>,
+}
+
+impl TempVarData {
+ pub(crate) fn new(last_term_arity: usize) -> Self {
+ TempVarData {
+ last_term_arity: last_term_arity,
+ use_set: BTreeSet::new(),
+ no_use_set: BTreeSet::new(),
+ conflict_set: BTreeSet::new(),
+ }
+ }
+
+ pub(crate) fn uses_reg(&self, reg: usize) -> bool {
+ for &(_, nreg) in self.use_set.iter() {
+ if reg == nreg {
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ pub(crate) fn populate_conflict_set(&mut self) {
+ if self.last_term_arity > 0 {
+ let arity = self.last_term_arity;
+ let mut conflict_set: BTreeSet<usize> = (1..arity).collect();
+
+ for &(_, reg) in self.use_set.iter() {
+ conflict_set.remove(®);
+ }
+
+ self.conflict_set = conflict_set;
+ }
+ }
+}
+
+type VariableFixture<'a> = (VarStatus, Vec<&'a Cell<VarReg>>);
+
+#[derive(Debug)]
+pub(crate) struct VariableFixtures<'a> {
+ perm_vars: IndexMap<Rc<String>, VariableFixture<'a>>,
+ last_chunk_temp_vars: IndexSet<Rc<String>>,
+}
+
+impl<'a> VariableFixtures<'a> {
+ pub(crate) fn new() -> Self {
+ VariableFixtures {
+ perm_vars: IndexMap::new(),
+ last_chunk_temp_vars: IndexSet::new(),
+ }
+ }
+
+ pub(crate) fn insert(&mut self, var: Rc<String>, vs: VariableFixture<'a>) {
+ self.perm_vars.insert(var, vs);
+ }
+
+ pub(crate) fn insert_last_chunk_temp_var(&mut self, var: Rc<String>) {
+ self.last_chunk_temp_vars.insert(var);
+ }
+
+ // computes no_use and conflict sets for all temp vars.
+ pub(crate) fn populate_restricting_sets(&mut self) {
+ // three stages:
+ // 1. move the use sets of each variable to a local IndexMap, use_set
+ // (iterate mutably, swap mutable refs).
+ // 2. drain use_set. For each use set of U, add into the
+ // no-use sets of appropriate variables T =/= U.
+ // 3. Move the use sets back to their original locations in the fixture.
+ // Compute the conflict set of u.
+
+ // 1.
+ let mut use_sets: IndexMap<Rc<String>, OccurrenceSet> = IndexMap::new();
+
+ for (var, &mut (ref mut var_status, _)) in self.iter_mut() {
+ if let &mut VarStatus::Temp(_, ref mut var_data) = var_status {
+ let mut use_set = OccurrenceSet::new();
+
+ swap(&mut var_data.use_set, &mut use_set);
+ use_sets.insert((*var).clone(), use_set);
+ }
+ }
+
+ for (u, use_set) in use_sets.drain(..) {
+ // 2.
+ for &(term_loc, reg) in use_set.iter() {
+ if let GenContext::Last(cn_u) = term_loc {
+ for (ref t, &mut (ref mut var_status, _)) in self.iter_mut() {
+ if let &mut VarStatus::Temp(cn_t, ref mut t_data) = var_status {
+ if cn_u == cn_t && *u != ***t {
+ if !t_data.uses_reg(reg) {
+ t_data.no_use_set.insert(reg);
+ }
+ }
+ }
+ }
+ }
+ }
+
+ // 3.
+ match self.get_mut(u).unwrap() {
+ &mut (VarStatus::Temp(_, ref mut u_data), _) => {
+ u_data.use_set = use_set;
+ u_data.populate_conflict_set();
+ }
+ _ => {}
+ };
+ }
+ }
+
+ fn get_mut(&mut self, u: Rc<String>) -> Option<&mut VariableFixture<'a>> {
+ self.perm_vars.get_mut(&u)
+ }
+
+ fn iter_mut(&mut self) -> indexmap::map::IterMut<Rc<String>, VariableFixture<'a>> {
+ self.perm_vars.iter_mut()
+ }
+
+ fn record_temp_info(&mut self, tvd: &mut TempVarData, arg_c: usize, term_loc: GenContext) {
+ match term_loc {
+ GenContext::Head | GenContext::Last(_) => {
+ tvd.use_set.insert((term_loc, arg_c));
+ }
+ _ => {}
+ };
+ }
+
+ pub(crate) fn vars_above_threshold(&self, index: usize) -> usize {
+ let mut var_count = 0;
+
+ for &(ref var_status, _) in self.values() {
+ if let &VarStatus::Perm(i) = var_status {
+ if i > index {
+ var_count += 1;
+ }
+ }
+ }
+
+ var_count
+ }
+
+ pub(crate) fn mark_vars_in_chunk<I>(&mut self, iter: I, lt_arity: usize, term_loc: GenContext)
+ where
+ I: Iterator<Item = TermRef<'a>>,
+ {
+ let chunk_num = term_loc.chunk_num();
+ let mut arg_c = 1;
+
+ for term_ref in iter {
+ if let &TermRef::Var(lvl, cell, ref var) = &term_ref {
+ let mut status = self.perm_vars.swap_remove(var).unwrap_or((
+ VarStatus::Temp(chunk_num, TempVarData::new(lt_arity)),
+ Vec::new(),
+ ));
+
+ status.1.push(cell);
+
+ match status.0 {
+ VarStatus::Temp(cn, ref mut tvd) if cn == chunk_num => {
+ if let Level::Shallow = lvl {
+ self.record_temp_info(tvd, arg_c, term_loc);
+ }
+ }
+ _ => status.0 = VarStatus::Perm(chunk_num),
+ };
+
+ self.perm_vars.insert(var.clone(), status);
+ }
+
+ if let Level::Shallow = term_ref.level() {
+ arg_c += 1;
+ }
+ }
+ }
+
+ pub(crate) fn into_iter(self) -> indexmap::map::IntoIter<Rc<String>, VariableFixture<'a>> {
+ self.perm_vars.into_iter()
+ }
+
+ fn values(&self) -> indexmap::map::Values<Rc<String>, VariableFixture<'a>> {
+ self.perm_vars.values()
+ }
+
+ pub(crate) fn size(&self) -> usize {
+ self.perm_vars.len()
+ }
+
+ pub(crate) fn set_perm_vals(&self, has_deep_cuts: bool) {
+ let mut values_vec: Vec<_> = self
+ .values()
+ .filter_map(|ref v| match &v.0 {
+ &VarStatus::Perm(i) => Some((i, &v.1)),
+ _ => None,
+ })
+ .collect();
+
+ values_vec.sort_by_key(|ref v| v.0);
+
+ let offset = has_deep_cuts as usize;
+
+ for (i, (_, cells)) in values_vec.into_iter().rev().enumerate() {
+ for cell in cells {
+ cell.set(VarReg::Norm(RegType::Perm(i + 1 + offset)));
+ }
+ }
+ }
+}
+
+#[derive(Debug)]
+pub(crate) struct UnsafeVarMarker {
+ pub(crate) unsafe_perm_vars: IndexMap<usize, usize>,
+ pub(crate) unsafe_temp_vars: IndexSet<usize>,
+ pub(crate) safe_perm_vars: IndexSet<usize>,
+ pub(crate) safe_temp_vars: IndexSet<usize>,
+ pub(crate) temp_vars_to_perm_vars: IndexMap<usize, usize>,
+ pub(crate) perm_vars_to_temp_vars: IndexMap<usize, usize>,
+}
+
+impl UnsafeVarMarker {
+ pub(crate) fn new() -> Self {
+ UnsafeVarMarker {
+ unsafe_perm_vars: IndexMap::new(),
+ unsafe_temp_vars: IndexSet::new(),
+ safe_perm_vars: IndexSet::new(),
+ safe_temp_vars: IndexSet::new(),
+ temp_vars_to_perm_vars: IndexMap::new(),
+ perm_vars_to_temp_vars: IndexMap::new(),
+ }
+ }
+
+ pub(crate) fn from_fact_vars(safe_vars: IndexSet<RegType>) -> Self {
+ let mut unsafe_var_marker = Self::new();
+
+ for r in safe_vars {
+ unsafe_var_marker.mark_var_as_safe(r);
+ }
+
+ unsafe_var_marker
+ }
+
+ fn mark_var_as_safe(&mut self, r: RegType) {
+ match r {
+ RegType::Temp(t) => {
+ self.safe_temp_vars.insert(t);
+ }
+ RegType::Perm(p) => {
+ self.safe_perm_vars.insert(p);
+ }
+ };
+ }
+
+ fn mark_var_as_unsafe(&mut self, r: RegType, phase: usize) {
+ match r {
+ RegType::Temp(t) => {
+ self.unsafe_temp_vars.insert(t);
+ }
+ RegType::Perm(p) => {
+ self.unsafe_perm_vars.insert(p, phase);
+ }
+ }
+ }
+
+ // returns true if the instruction at *query_instr cannot be
+ // changed by mark_unsafe_vars.
+ fn mark_safe_vars(&mut self, query_instr: &Instruction) -> bool {
+ match query_instr {
+ &Instruction::PutVariable(r @ RegType::Temp(_), _) |
+ &Instruction::SetVariable(r) => {
+ self.mark_var_as_safe(r);
+ true
+ }
+ &Instruction::PutVariable(RegType::Perm(p), t) => {
+ self.temp_vars_to_perm_vars.insert(t, p);
+ true
+ }
+ &Instruction::CallIs(RegType::Temp(t), ..) => {
+ if let Some(p) = self.temp_vars_to_perm_vars.get(&t) {
+ self.mark_var_as_safe(RegType::Perm(*p));
+ }
+
+ true
+ }
+ _ => false,
+ }
+ }
+
+ fn mark_phase(&mut self, query_instr: &Instruction, phase: usize) {
+ match query_instr {
+ &Instruction::PutValue(r @ RegType::Perm(_), _) |
+ &Instruction::SetValue(r) => {
+ self.mark_var_as_unsafe(r, phase);
+ }
+ _ => {}
+ }
+ }
+
+ fn mark_unsafe_perm_vars(&mut self, query_instr: &mut Instruction, phase: usize) {
+ match query_instr {
+ &mut Instruction::PutValue(RegType::Perm(p), arg)
+ if !self.safe_perm_vars.contains(&p) => {
+ if let Some(ph) = self.unsafe_perm_vars.swap_remove(&p) {
+ if ph == phase {
+ *query_instr = Instruction::PutUnsafeValue(p, arg);
+ self.perm_vars_to_temp_vars.insert(p, arg);
+ } else {
+ self.unsafe_perm_vars.insert(p, ph);
+ }
+ }
+ }
+ &mut Instruction::SetValue(r @ RegType::Perm(p)) =>
+ if let Some(t) = self.perm_vars_to_temp_vars.get(&p) {
+ *query_instr = Instruction::SetValue(RegType::Temp(*t));
+ } else {
+ *query_instr = Instruction::SetLocalValue(r);
+
+ self.safe_perm_vars.insert(p);
+ self.unsafe_perm_vars.remove(&p);
+ }
+ _ => {}
+ }
+ }
+
+ fn mark_unsafe_temp_vars(&mut self, query_instr: &mut Instruction) {
+ match query_instr {
+ &mut Instruction::SetValue(r @ RegType::Temp(t))
+ if !self.safe_temp_vars.contains(&t) => {
+ *query_instr = Instruction::SetLocalValue(r);
+
+ self.safe_temp_vars.insert(t);
+ self.unsafe_temp_vars.remove(&t);
+ }
+ _ => {
+ }
+ }
+ }
+
+ fn clear_temp_vars(&mut self) {
+ self.safe_temp_vars.clear();
+ self.unsafe_temp_vars.clear();
+ self.temp_vars_to_perm_vars.clear();
+ }
+
+ pub(crate) fn mark_unsafe_instrs(&mut self, code: &mut Code) {
+ if code.is_empty() {
+ return;
+ }
+
+ let mut code_index = 0;
+
+ for phase in 0.. {
+ while code[code_index].is_query_instr() {
+ let query_instr = &mut code[code_index];
+
+ if !self.mark_safe_vars(query_instr) {
+ self.mark_phase(query_instr, phase);
+ self.mark_unsafe_temp_vars(query_instr);
+ }
+
+ code_index += 1;
+ }
+
+ while code_index < code.len() && !code[code_index].is_query_instr() {
+ self.mark_safe_vars(&code[code_index]);
+ code_index += 1;
+ }
+
+ self.clear_temp_vars();
+
+ if code_index >= code.len() {
+ break;
+ }
+ }
+
+ code_index = 0;
+
+ for phase in 0.. {
+ while code[code_index].is_query_instr() {
+ let query_instr = &mut code[code_index];
+ self.mark_unsafe_perm_vars(query_instr, phase);
+ code_index += 1;
+ }
+
+ // ensure phase->instruction assignments match those of
+ // the previous for loop.
+ while code_index < code.len() && !code[code_index].is_query_instr() {
+ code_index += 1;
+ }
+
+ if code_index >= code.len() {
+ break;
+ }
+ }
+ }
+}
projects / scryer-prolog.git / commitdiff