src/compiler-rt/lib/builtins/comparedf2.c

   1 //===-- lib/comparedf2.c - Double-precision comparisons -----------*- C -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is dual licensed under the MIT and the University of Illinois Open
   6 // Source Licenses. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // // This file implements the following soft-float comparison routines:
  11 //
  12 //   __eqdf2   __gedf2   __unorddf2
  13 //   __ledf2   __gtdf2
  14 //   __ltdf2
  15 //   __nedf2
  16 //
  17 // The semantics of the routines grouped in each column are identical, so there
  18 // is a single implementation for each, and wrappers to provide the other names.
  19 //
  20 // The main routines behave as follows:
  21 //
  22 //   __ledf2(a,b) returns -1 if a < b
  23 //                         0 if a == b
  24 //                         1 if a > b
  25 //                         1 if either a or b is NaN
  26 //
  27 //   __gedf2(a,b) returns -1 if a < b
  28 //                         0 if a == b
  29 //                         1 if a > b
  30 //                        -1 if either a or b is NaN
  31 //
  32 //   __unorddf2(a,b) returns 0 if both a and b are numbers
  33 //                           1 if either a or b is NaN
  34 //
  35 // Note that __ledf2( ) and __gedf2( ) are identical except in their handling of
  36 // NaN values.
  37 //
  38 //===----------------------------------------------------------------------===//
  39
  40 #define DOUBLE_PRECISION
  41 #include "fp_lib.h"
  42
  43 enum LE_RESULT {
  44     LE_LESS      = -1,
  45     LE_EQUAL     =  0,
  46     LE_GREATER   =  1,
  47     LE_UNORDERED =  1
  48 };
  49
  50 COMPILER_RT_ABI enum LE_RESULT
  51 __ledf2(fp_t a, fp_t b) {
  52
  53     const srep_t aInt = toRep(a);
  54     const srep_t bInt = toRep(b);
  55     const rep_t aAbs = aInt & absMask;
  56     const rep_t bAbs = bInt & absMask;
  57
  58     // If either a or b is NaN, they are unordered.
  59     if (aAbs > infRep || bAbs > infRep) return LE_UNORDERED;
  60
  61     // If a and b are both zeros, they are equal.
  62     if ((aAbs | bAbs) == 0) return LE_EQUAL;
  63
  64     // If at least one of a and b is positive, we get the same result comparing
  65     // a and b as signed integers as we would with a floating-point compare.
  66     if ((aInt & bInt) >= 0) {
  67         if (aInt < bInt) return LE_LESS;
  68         else if (aInt == bInt) return LE_EQUAL;
  69         else return LE_GREATER;
  70     }
  71
  72     // Otherwise, both are negative, so we need to flip the sense of the
  73     // comparison to get the correct result.  (This assumes a twos- or ones-
  74     // complement integer representation; if integers are represented in a
  75     // sign-magnitude representation, then this flip is incorrect).
  76     else {
  77         if (aInt > bInt) return LE_LESS;
  78         else if (aInt == bInt) return LE_EQUAL;
  79         else return LE_GREATER;
  80     }
  81 }
  82
  83 #if defined(__ELF__)
  84 // Alias for libgcc compatibility
  85 FNALIAS(__cmpdf2, __ledf2);
  86 #endif
  87
  88 enum GE_RESULT {
  89     GE_LESS      = -1,
  90     GE_EQUAL     =  0,
  91     GE_GREATER   =  1,
  92     GE_UNORDERED = -1   // Note: different from LE_UNORDERED
  93 };
  94
  95 COMPILER_RT_ABI enum GE_RESULT
  96 __gedf2(fp_t a, fp_t b) {
  97
  98     const srep_t aInt = toRep(a);
  99     const srep_t bInt = toRep(b);
 100     const rep_t aAbs = aInt & absMask;
 101     const rep_t bAbs = bInt & absMask;
 102
 103     if (aAbs > infRep || bAbs > infRep) return GE_UNORDERED;
 104     if ((aAbs | bAbs) == 0) return GE_EQUAL;
 105     if ((aInt & bInt) >= 0) {
 106         if (aInt < bInt) return GE_LESS;
 107         else if (aInt == bInt) return GE_EQUAL;
 108         else return GE_GREATER;
 109     } else {
 110         if (aInt > bInt) return GE_LESS;
 111         else if (aInt == bInt) return GE_EQUAL;
 112         else return GE_GREATER;
 113     }
 114 }
 115
 116 ARM_EABI_FNALIAS(dcmpun, unorddf2)
 117
 118 COMPILER_RT_ABI int
 119 __unorddf2(fp_t a, fp_t b) {
 120     const rep_t aAbs = toRep(a) & absMask;
 121     const rep_t bAbs = toRep(b) & absMask;
 122     return aAbs > infRep || bAbs > infRep;
 123 }
 124
 125 // The following are alternative names for the preceding routines.
 126
 127 COMPILER_RT_ABI enum LE_RESULT
 128 __eqdf2(fp_t a, fp_t b) {
 129     return __ledf2(a, b);
 130 }
 131
 132 COMPILER_RT_ABI enum LE_RESULT
 133 __ltdf2(fp_t a, fp_t b) {
 134     return __ledf2(a, b);
 135 }
 136
 137 COMPILER_RT_ABI enum LE_RESULT
 138 __nedf2(fp_t a, fp_t b) {
 139     return __ledf2(a, b);
 140 }
 141
 142 COMPILER_RT_ABI enum GE_RESULT
 143 __gtdf2(fp_t a, fp_t b) {
 144     return __gedf2(a, b);
 145 }
 146