[clang-tools-extra] [MLIR][Presburger] Implement matrix inverse (PR #67382)

[Arjun P via cfe-commits]

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@@ -241,6 +245,32 @@ class IntMatrix : public Matrix<MPInt>
   /// Returns the GCD of the columns of the specified row.
   MPInt normalizeRow(unsigned row);
 
+  // Return the integer inverse of the matrix, leaving the calling object
+  // unmodified.
+  std::optional<IntMatrix> integerInverse();
+};
+
+// An inherited class for rational matrices, with no new data attributes.
+// This class is for functionality that only applies to matrices of fractions.
+class FracMatrix : public Matrix<Fraction> {
+public:
+  FracMatrix(unsigned rows, unsigned columns, unsigned reservedRows = 0,
+             unsigned reservedColumns = 0)
+      : Matrix<Fraction>(rows, columns, reservedRows, reservedColumns){};
+
+  FracMatrix(Matrix<Fraction> m)
+      : Matrix<Fraction>(m.getNumRows(), m.getNumColumns(),
+                         m.getNumReservedRows(), m.getNumReservedColumns()) {
+    for (unsigned i = 0; i < m.getNumRows(); i++)
+      for (unsigned j = 0; j < m.getNumColumns(); j++)
+        at(i, j) = m(i, j);
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Superty wrote:

`: Matrix<Fraction(m)`?

https://github.com/llvm/llvm-project/pull/67382