lib/builtins/comparetf2.c

//===-- lib/comparetf2.c - Quad-precision comparisons -------------*- 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
//
//===----------------------------------------------------------------------===//
//
// // This file implements the following soft-float comparison routines:
//
//   __eqtf2   __getf2   __unordtf2
//   __letf2   __gttf2
//   __lttf2
//   __netf2
//
// The semantics of the routines grouped in each column are identical, so there
// is a single implementation for each, and wrappers to provide the other names.
//
// The main routines behave as follows:
//
//   __letf2(a,b) returns -1 if a < b
//                         0 if a == b
//                         1 if a > b
//                         1 if either a or b is NaN
//
//   __getf2(a,b) returns -1 if a < b
//                         0 if a == b
//                         1 if a > b
//                        -1 if either a or b is NaN
//
//   __unordtf2(a,b) returns 0 if both a and b are numbers
//                           1 if either a or b is NaN
//
// Note that __letf2( ) and __getf2( ) are identical except in their handling of
// NaN values.
//
//===----------------------------------------------------------------------===//

#define QUAD_PRECISION
#include "fp_lib.h"

#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
enum LE_RESULT { LE_LESS = -1, LE_EQUAL = 0, LE_GREATER = 1, LE_UNORDERED = 1 };

COMPILER_RT_ABI enum LE_RESULT __letf2(fp_t a, fp_t b) {

  const srep_t aInt = toRep(a);
  const srep_t bInt = toRep(b);
  const rep_t aAbs = aInt & absMask;
  const rep_t bAbs = bInt & absMask;

  // If either a or b is NaN, they are unordered.
  if (aAbs > infRep || bAbs > infRep)
    return LE_UNORDERED;

  // If a and b are both zeros, they are equal.
  if ((aAbs | bAbs) == 0)
    return LE_EQUAL;

  // If at least one of a and b is positive, we get the same result comparing
  // a and b as signed integers as we would with a floating-point compare.
  if ((aInt & bInt) >= 0) {
    if (aInt < bInt)
      return LE_LESS;
    else if (aInt == bInt)
      return LE_EQUAL;
    else
      return LE_GREATER;
  } else {
    // Otherwise, both are negative, so we need to flip the sense of the
    // comparison to get the correct result.  (This assumes a twos- or ones-
    // complement integer representation; if integers are represented in a
    // sign-magnitude representation, then this flip is incorrect).
    if (aInt > bInt)
      return LE_LESS;
    else if (aInt == bInt)
      return LE_EQUAL;
    else
      return LE_GREATER;
  }
}

#if defined(__ELF__)
// Alias for libgcc compatibility
COMPILER_RT_ALIAS(__letf2, __cmptf2)
#endif
COMPILER_RT_ALIAS(__letf2, __eqtf2)
COMPILER_RT_ALIAS(__letf2, __lttf2)
COMPILER_RT_ALIAS(__letf2, __netf2)

enum GE_RESULT {
  GE_LESS = -1,
  GE_EQUAL = 0,
  GE_GREATER = 1,
  GE_UNORDERED = -1 // Note: different from LE_UNORDERED
};

COMPILER_RT_ABI enum GE_RESULT __getf2(fp_t a, fp_t b) {

  const srep_t aInt = toRep(a);
  const srep_t bInt = toRep(b);
  const rep_t aAbs = aInt & absMask;
  const rep_t bAbs = bInt & absMask;

  if (aAbs > infRep || bAbs > infRep)
    return GE_UNORDERED;
  if ((aAbs | bAbs) == 0)
    return GE_EQUAL;
  if ((aInt & bInt) >= 0) {
    if (aInt < bInt)
      return GE_LESS;
    else if (aInt == bInt)
      return GE_EQUAL;
    else
      return GE_GREATER;
  } else {
    if (aInt > bInt)
      return GE_LESS;
    else if (aInt == bInt)
      return GE_EQUAL;
    else
      return GE_GREATER;
  }
}

COMPILER_RT_ALIAS(__getf2, __gttf2)

COMPILER_RT_ABI int __unordtf2(fp_t a, fp_t b) {
  const rep_t aAbs = toRep(a) & absMask;
  const rep_t bAbs = toRep(b) & absMask;
  return aAbs > infRep || bAbs > infRep;
}

#endif