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Fix memory leak in undo_fixed_column for big numbers

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The undo_fixed_column struct is region-allocated via trail_stack, so its
destructor is never called. When m_fixed_val contains a big number (one
that doesn't fit in a small int), the heap-allocated memory for the mpq
numerator/denominator was never freed.

Fix by calling m_fixed_val.reset() in undo() to explicitly free the
heap memory before the region deallocates the struct.

Verified with macOS leaks tool:
- Before: 126 leaks (6048 bytes) on convert-jpg2gif-query-1584.smt2
- After: 0 leaks on normal completion, 10 leaks on timeout (unfinished trail)
This commit is contained in:
Lev Nachmanson 2026-01-24 08:16:08 -10:00 • committed by Nikolaj Bjorner
parent 392a26b619
commit 6bce4c2b81
1 changed files with 4 additions and 1 deletions
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5
src/math/lp/dioph_eq.cpp
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@ -654,13 +654,16 @@ namespace lp {
struct undo_fixed_column : public trail { struct undo_fixed_column : public trail {
imp& m_imp; imp& m_imp;
unsigned m_j; // the column that has been added unsigned m_j; // the column that has been added
const mpq m_fixed_val; mpq m_fixed_val; // not const: needs to be reset in undo() to free heap memory
undo_fixed_column(imp& s, unsigned j) : m_imp(s), m_j(j), m_fixed_val(s.lra.get_lower_bound(j).x) { undo_fixed_column(imp& s, unsigned j) : m_imp(s), m_j(j), m_fixed_val(s.lra.get_lower_bound(j).x) {
SASSERT(s.lra.column_is_fixed(j)); SASSERT(s.lra.column_is_fixed(j));
} }
void undo() override { void undo() override {
m_imp.add_changed_column(m_j); m_imp.add_changed_column(m_j);
// Free heap-allocated memory in m_fixed_val since this struct is region-allocated
// and its destructor won't be called
m_fixed_val.reset();
} }
}; };