[clang] [llvm] [clang][dataflow] Make `CNFFormula` externally accessible. (PR #92401)

[Stanislav Gatev via llvm-commits]

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@@ -0,0 +1,180 @@
+//===- CNFFormula.h ---------------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+//  A representation of a boolean formula in 3-CNF.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_CNFFORMULA_H
+#define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_CNFFORMULA_H
+
+#include <cstdint>
+#include <vector>
+
+#include "clang/Analysis/FlowSensitive/Formula.h"
+
+namespace clang {
+namespace dataflow {
+
+/// Boolean variables are represented as positive integers.
+using Variable = uint32_t;
+
+/// A null boolean variable is used as a placeholder in various data structures
+/// and algorithms.
+constexpr Variable NullVar = 0;
+
+/// Literals are represented as positive integers. Specifically, for a boolean
+/// variable `V` that is represented as the positive integer `I`, the positive
+/// literal `V` is represented as the integer `2*I` and the negative literal
+/// `!V` is represented as the integer `2*I+1`.
+using Literal = uint32_t;
+
+/// A null literal is used as a placeholder in various data structures and
+/// algorithms.
+constexpr Literal NullLit = 0;
+
+/// Clause identifiers are represented as positive integers.
+using ClauseID = uint32_t;
+
+/// A null clause identifier is used as a placeholder in various data structures
+/// and algorithms.
+constexpr ClauseID NullClause = 0;
+
+/// Returns the positive literal `V`.
+inline constexpr Literal posLit(Variable V) { return 2 * V; }
+
+/// Returns whether `L` is a positive literal.
+inline constexpr bool isPosLit(Literal L) { return 0 == (L & 1); }
+
+/// Returns whether `L` is a negative literal.
+inline constexpr bool isNegLit(Literal L) { return 1 == (L & 1); }
+
+/// Returns the negative literal `!V`.
+inline constexpr Literal negLit(Variable V) { return 2 * V + 1; }
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sgatev wrote:

Nit: I suggest moving this below `posLit` so that the two constructor functions are next to each other.

https://github.com/llvm/llvm-project/pull/92401