ZIPT review identified two hot-path inefficiencies in `euf_sgraph`:
`drop_left`/`drop_right` were implemented as repeated single-token drops
(`O(count × depth)`), and `classify` performed redundant string checks.
This change aligns behavior with the intended tree-navigation approach
while keeping semantics unchanged.
- **Algorithmic update: `drop_left` / `drop_right`**
- Replaced iterative `drop_first`/`drop_last` loops with direct
recursion over concat children.
- New logic drops across subtree boundaries using child lengths,
reducing work to tree depth (`O(depth)`).
- **Classification cleanup: `classify`**
- Collapsed double `is_string` probing into a single `is_string(e, s)`
call.
- Preserves existing kind mapping (`empty` vs non-empty string constant
handling).
- **Focused test coverage extension**
- Added boundary checks in `test_sgraph_drop` for `drop_left(..., 1)`
and `drop_right(..., 1)` on a 4-token concat tree.
```cpp
snode* sgraph::drop_left(snode* n, unsigned count) {
if (count == 0 || n->is_empty()) return n;
if (count >= n->length()) return mk_empty_seq(n->get_sort());
SASSERT(n->is_concat());
unsigned left_len = n->arg(0)->length();
if (count < left_len)
return mk_concat(drop_left(n->arg(0), count), n->arg(1));
return drop_left(n->arg(1), count - left_len);
}
```
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
`euf_seq_plugin` was applying several regex concat simplifications
against raw child enodes instead of canonical e-graph roots, so rules
could silently miss after merges. It also merged loop bounds with
unchecked unsigned addition, allowing overflowed bounds.
- **Root-canonical checks in simplification rules**
- Use `get_root()` for nullable/full-seq absorption checks.
- Update `same_star_body` to test `is_star` on roots and compare rooted
star bodies.
- Evaluate extended star rules (`v*.v*.c` / `c.v*.v*`) against concat
roots, not syntactic children.
- **Safe loop merge arithmetic**
- Gate loop merging on overflow-safe bound addition checks before
constructing merged `re.loop`.
- **Re-simplify concats affected by child merges**
- In `propagate_merge`, re-run `propagate_simplify` for tracked concat
nodes whose left/right child root is in the merged class, not only
concats in the class itself.
- **Regression coverage in `src/test/euf_seq_plugin.cpp`**
- Added focused tests for:
- star merge firing after child-to-star merge,
- extended star rule using root concat shape,
- nullable absorption via merged roots,
- loop-merge non-application on overflow.
```cpp
// before: structural check on non-canonical enode
if (is_concat(b, b1, b2) && same_star_body(a, b1))
// after: structural check on canonical representative
if (is_concat(b->get_root(), b1, b2) && same_star_body(a, b1))
```
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
While working on https://github.com/Z3Prover/z3/pull/9405, I noticed
that euf_mam.cpp code was slightly out of sync with mam.cpp and did some
redundant work.
Co-authored-by: Can Cebeci <t-cancebeci@microsoft.com>
- only the internalizer performs closure conversion
- theory_array treats propagation of lambdas similar to stores
- ho_matcher treats top-level flex patterns as first-order
- pattern-inference fix to handle quantifiers (lambdas) in patterns that are computed
* Compute term generations based on minimal match
* Tidy up get_*_f_app
* Update euf_mam to the minimum generation number among matches
* Update euf_mam.cpp
* Move the UNREACHABLE() test to smt_mam.cpp
* Enforce stickiness of max-generation
* Add current generation tracking to bind structure
* Fix build error
---------
Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com>
