[Mlir-commits] [mlir] [MLIR][Presburger] Generating functions and quasi-polynomials for Barvinok's algorithm (PR #75702)

[Arjun P]

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+//===- QuasiPolynomial.cpp - Quasipolynomial Class --------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Analysis/Presburger/QuasiPolynomial.h"
+#include "mlir/Analysis/Presburger/Fraction.h"
+#include "mlir/Analysis/Presburger/IntegerRelation.h"
+#include "mlir/Analysis/Presburger/Matrix.h"
+#include "mlir/Analysis/Presburger/PresburgerSpace.h"
+#include "mlir/Analysis/Presburger/Utils.h"
+#include "mlir/Support/LogicalResult.h"
+#include <optional>
+
+using namespace mlir;
+using namespace presburger;
+
+QuasiPolynomial::QuasiPolynomial(
+    unsigned numParam, SmallVector<Fraction> coeffs,
+    std::vector<std::vector<SmallVector<Fraction>>> aff)
+    : numParam(numParam), coefficients(coeffs), affine(aff) {
+  // Find the first term which involves some affine function.
+  for (const std::vector<SmallVector<Fraction>> &term : affine) {
+    if (term.size() == 0)
+      continue;
+    // The number of elements in the affine function is
+    // one more than the number of parameters.
+    assert(term[0].size() - 1 == numParam &&
+           "dimensionality of affine functions does not match number of "
+           "parameters!");
+  }
+}
+
+// Find the number of parameters involved in the polynomial.
+unsigned QuasiPolynomial::getNumParams() { return numParam; }
+
+SmallVector<Fraction> QuasiPolynomial::getCoefficients() {
+  return coefficients;
+}
+
+std::vector<std::vector<SmallVector<Fraction>>> QuasiPolynomial::getAffine() {
+  return affine;
+}
+
+// Removes terms which evaluate to zero from the expression.
+QuasiPolynomial QuasiPolynomial::simplify() {
+  SmallVector<Fraction> newCoeffs({});
+  std::vector<std::vector<SmallVector<Fraction>>> newAffine({});
+  for (unsigned i = 0, e = coefficients.size(); i < e; i++) {
+    // A term is zero if its coefficient is zero, or
+    if (coefficients[i] == Fraction(0, 1) ||
+        // if any of the affine functions in the product
+        llvm::any_of(affine[i], [](SmallVector<Fraction> affine_ij) {
----------------
Superty wrote:

please use references `const SmallVector<Fraction> &affine_ij`, `const &Fraction f` here and below otherwise by default you're copying everything which is slower

https://github.com/llvm/llvm-project/pull/75702