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correct copying of cyclic lists in copier.rs

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This commit is contained in:
Mark Thom
2019-12-02 17:06:12 -04:00
parent 406d3520f1
commit fc8e55c582
1 changed files with 30 additions and 9 deletions
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25
src/prolog/machine/copier.rs
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@@ -51,13 +51,16 @@ impl<T: CopierTarget> CopyTermState<T> {
} }
fn copied_list(&mut self, addr: usize) -> bool { fn copied_list(&mut self, addr: usize) -> bool {
if let HeapCellValue::Addr(Addr::Lis(addr)) = self.target[addr].clone() { match self.target[addr].clone() {
HeapCellValue::Addr(Addr::Lis(addr)) | HeapCellValue::Addr(Addr::HeapCell(addr)) => {
if addr >= self.old_h { if addr >= self.old_h {
*self.value_at_scan() = HeapCellValue::Addr(Addr::Lis(addr)); *self.value_at_scan() = HeapCellValue::Addr(Addr::Lis(addr));
self.scan += 1; self.scan += 1;
return true; return true;
} }
} }
_ => {}
};
false false
} }
@@ -71,13 +74,31 @@ impl<T: CopierTarget> CopyTermState<T> {
*self.value_at_scan() = HeapCellValue::Addr(Addr::Lis(threshold)); *self.value_at_scan() = HeapCellValue::Addr(Addr::Lis(threshold));
let hcv = self.target[addr].clone(); let hcv = self.target[addr].clone();
let ra = hcv.as_addr(threshold);
let rd = self.target.store(self.target.deref(ra));
self.target.push(hcv); self.target.push(hcv);
let hcv = self.target[addr + 1].clone(); let hcv = self.target[addr + 1].clone();
self.target.push(hcv); self.target.push(hcv);
match rd.clone() {
Addr::AttrVar(h) | Addr::HeapCell(h) if h >= self.old_h => {
self.target[threshold] = HeapCellValue::Addr(rd)
}
ra @ Addr::AttrVar(_) | ra @ Addr::HeapCell(..) | ra @ Addr::StackCell(..) => {
if ra == rd {
self.reinstantiate_var(ra, threshold);
} else {
self.target[threshold] = HeapCellValue::Addr(ra);
}
}
_ => {
self.trail.push((Ref::HeapCell(addr), self.target[addr].clone())); self.trail.push((Ref::HeapCell(addr), self.target[addr].clone()));
self.target[addr] = HeapCellValue::Addr(Addr::Lis(threshold)); self.target[addr] = HeapCellValue::Addr(Addr::Lis(threshold))
}
};
self.scan += 1; self.scan += 1;
} }