[Mlir-commits] [mlir] [MLIR][Presburger] Definitions for basic functions related to cones (PR #76650)

[Kunwar Grover]

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@@ -0,0 +1,66 @@
+//===- QuasiPolynomial.cpp - Barvinok's Algorithm ---------------*- 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/Barvinok.h"
+
+using namespace mlir;
+using namespace presburger;
+using namespace mlir::presburger::detail;
+
+// Assuming that the input cone is pointed at the origin,
+// converts it to its dual in V-representation.
+// Essentially we just remove the all-zeroes constant column.
+ConeV mlir::presburger::detail::getDual(ConeH cone) {
+  unsigned numIneq = cone.getNumInequalities();
+  unsigned numVar = cone.getNumCols() - 1;
+  ConeV dual(numIneq, numVar, 0, 0);
+  // Assuming that an inequality of the form
+  // a1*x1 + ... + an*xn + b ≥ 0
+  // is represented as a row [a1, ..., an, b]
+  // and that b = 0.
+
+  for (unsigned i = 0; i < numIneq; i++) {
+    assert(cone.atIneq(i, numVar) == 0 &&
+           "H-representation of cone is not centred at the origin!");
+    for (unsigned j = 0; j < numVar; j++) {
+      dual.at(i, j) = cone.atIneq(i, j);
+    }
+  }
+
+  // Now dual is of the form [ [a1, ..., an] , ... ]
+  // which is the V-representation of the dual.
+  return dual;
+}
+
+// Converts a cone in V-representation to the H-representation
+// of its dual, pointed at the origin (not at the original vertex).
+// Essentially adds a column consisting only of zeroes to the end.
+ConeH mlir::presburger::detail::getDual(ConeV cone) {
+  unsigned rows = cone.getNumRows();
+  unsigned columns = cone.getNumColumns();
+  ConeH dual = defineHRep(columns);
+  // Add a new column (for constants) at the end.
+  // This will be initialized to zero.
+  cone.insertColumn(columns);
+
+  for (unsigned i = 0; i < rows; i++)
+    dual.addInequality(cone.getRow(i));
+
+  // Now dual is of the form [ [a1, ..., an, 0] , ... ]
+  // which is the H-representation of the dual.
+  return dual;
+}
+
+// Find the index of a cone in V-representation.
+// If there are more rays than variables, return 0.
----------------
Groverkss wrote:

This seems like a usage detaol than an implementation detail. This should be in the header file, not here.

https://github.com/llvm/llvm-project/pull/76650