path: root/include/llvm/ADT/APInt.h

//===-- llvm/ADT/APInt.h - For Arbitrary Precision Integer -----*- C++ -*--===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a class to represent arbitrary precision integral
// constant values and operations on them.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_APINT_H
#define LLVM_APINT_H

#include "llvm/Support/DataTypes.h"
#include <cassert>
#include <string>

#define COMPILE_TIME_ASSERT(cond) extern int CTAssert[(cond) ? 1 : -1]

namespace llvm {
  class Serializer;
  class Deserializer;
  class FoldingSetNodeID;
  
  /* An unsigned host type used as a single part of a multi-part
     bignum.  */
  typedef uint64_t integerPart;

  const unsigned int host_char_bit = 8;
  const unsigned int integerPartWidth = host_char_bit * sizeof(integerPart);

//===----------------------------------------------------------------------===//
//                              APInt Class
//===----------------------------------------------------------------------===//

/// APInt - This class represents arbitrary precision constant integral values.
/// It is a functional replacement for common case unsigned integer type like 
/// "unsigned", "unsigned long" or "uint64_t", but also allows non-byte-width 
/// integer sizes and large integer value types such as 3-bits, 15-bits, or more
/// than 64-bits of precision. APInt provides a variety of arithmetic operators 
/// and methods to manipulate integer values of any bit-width. It supports both
/// the typical integer arithmetic and comparison operations as well as bitwise
/// manipulation.
///
/// The class has several invariants worth noting:
///   * All bit, byte, and word positions are zero-based.
///   * Once the bit width is set, it doesn't change except by the Truncate, 
///     SignExtend, or ZeroExtend operations.
///   * All binary operators must be on APInt instances of the same bit width.
///     Attempting to use these operators on instances with different bit 
///     widths will yield an assertion.
///   * The value is stored canonically as an unsigned value. For operations
///     where it makes a difference, there are both signed and unsigned variants
///     of the operation. For example, sdiv and udiv. However, because the bit
///     widths must be the same, operations such as Mul and Add produce the same
///     results regardless of whether the values are interpreted as signed or
///     not.
///   * In general, the class tries to follow the style of computation that LLVM
///     uses in its IR. This simplifies its use for LLVM.
///
/// @brief Class for arbitrary precision integers.
class APInt {

  uint32_t BitWidth;      ///< The number of bits in this APInt.

  /// This union is used to store the integer value. When the
  /// integer bit-width <= 64, it uses VAL, otherwise it uses pVal.
  union {
    uint64_t VAL;    ///< Used to store the <= 64 bits integer value.
    uint64_t *pVal;  ///< Used to store the >64 bits integer value.
  };

  /// This enum is used to hold the constants we needed for APInt.
  enum {
    APINT_BITS_PER_WORD = sizeof(uint64_t) * 8, ///< Bits in a word
    APINT_WORD_SIZE = sizeof(uint64_t)          ///< Byte size of a word
  };

  /// This constructor is used only internally for speed of construction of
  /// temporaries. It is unsafe for general use so it is not public.
  /// @brief Fast internal constructor
  APInt(uint64_t* val, uint32_t bits) : </