libatomic/config/x86/fenv.c

   1 /* Copyright (C) 2013-2023 Free Software Foundation, Inc.
   2
   3    This file is part of the GNU Atomic Library (libatomic).
   4
   5    Libatomic is free software; you can redistribute it and/or modify it
   6    under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    Libatomic is distributed in the hope that it will be useful, but WITHOUT ANY
  11    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  12    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13    more details.
  14
  15    Under Section 7 of GPL version 3, you are granted additional
  16    permissions described in the GCC Runtime Library Exception, version
  17    3.1, as published by the Free Software Foundation.
  18
  19    You should have received a copy of the GNU General Public License and
  20    a copy of the GCC Runtime Library Exception along with this program;
  21    see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22    <http://www.gnu.org/licenses/>.  */
  23
  24 #include "libatomic_i.h"
  25
  26 #define FE_INVALID      0x01
  27 #define FE_DENORM       0x02
  28 #define FE_DIVBYZERO    0x04
  29 #define FE_OVERFLOW     0x08
  30 #define FE_UNDERFLOW    0x10
  31 #define FE_INEXACT      0x20
  32
  33 struct fenv
  34 {
  35   unsigned short int __control_word;
  36   unsigned short int __unused1;
  37   unsigned short int __status_word;
  38   unsigned short int __unused2;
  39   unsigned short int __tags;
  40   unsigned short int __unused3;
  41   unsigned int __eip;
  42   unsigned short int __cs_selector;
  43   unsigned int __opcode:11;
  44   unsigned int __unused4:5;
  45   unsigned int __data_offset;
  46   unsigned short int __data_selector;
  47   unsigned short int __unused5;
  48 } __attribute__ ((gcc_struct));
  49
  50 #ifdef __SSE_MATH__
  51 # define __math_force_eval_div(x, y) \
  52   do { asm ("" : "+x" (x)); asm volatile ("" : : "x" (x / y)); } while (0)
  53 #else
  54 # define __math_force_eval_div(x, y) \
  55   do { asm ("" : "+t" (x)); asm volatile ("" : : "f" (x / y)); } while (0)
  56 #endif
  57
  58 /* Raise the supported floating-point exceptions from EXCEPTS.  Other
  59    bits in EXCEPTS are ignored.  */
  60
  61 void
  62 __atomic_feraiseexcept (int excepts)
  63 {
  64   struct fenv temp;
  65
  66   if (excepts & FE_INVALID)
  67     {
  68       float f = 0.0f;
  69       __math_force_eval_div (f, f);
  70     }
  71   if (excepts & FE_DENORM)
  72     {
  73       asm volatile ("fnstenv\t%0" : "=m" (temp));
  74       temp.__status_word |= FE_DENORM;
  75       asm volatile ("fldenv\t%0" : : "m" (temp));
  76       asm volatile ("fwait");
  77     }
  78   if (excepts & FE_DIVBYZERO)
  79     {
  80       float f = 1.0f, g = 0.0f;
  81       __math_force_eval_div (f, g);
  82     }
  83   if (excepts & FE_OVERFLOW)
  84     {
  85       asm volatile ("fnstenv\t%0" : "=m" (temp));
  86       temp.__status_word |= FE_OVERFLOW;
  87       asm volatile ("fldenv\t%0" : : "m" (temp));
  88       asm volatile ("fwait");
  89     }
  90   if (excepts & FE_UNDERFLOW)
  91     {
  92       asm volatile ("fnstenv\t%0" : "=m" (temp));
  93       temp.__status_word |= FE_UNDERFLOW;
  94       asm volatile ("fldenv\t%0" : : "m" (temp));
  95       asm volatile ("fwait");
  96     }
  97   if (excepts & FE_INEXACT)
  98     {
  99       float f = 1.0f, g = 3.0f;
 100       __math_force_eval_div (f, g);
 101     }
 102 }