libgcc/config/rs6000/_powikf2.c

   1 /* Copyright (C) 1989-2024 Free Software Foundation, Inc.
   2
   3 This file is part of GCC.
   4
   5 GCC is free software; you can redistribute it and/or modify it under
   6 the terms of the GNU General Public License as published by the Free
   7 Software Foundation; either version 3, or (at your option) any later
   8 version.
   9
  10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13 for 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 "soft-fp.h"
  25 #include "quad-float128.h"
  26
  27 /* __powikf3 can be compiled 3 different ways:
  28
  29    1) If the assembler does not have support for the IEEE 128-bit insns
  30    (xsaddqp, etc.) it is just compiled as __powikf2.
  31
  32    2) If the assembler has IEEE 128-bit floating point support, and __powikf2
  33    is not previously defined, it is defined as __powikf2_sw.
  34
  35    3) If the assembler has IEEE 128-bit floating point support, and __powikf2
  36    is included by _powikf2-hw.c, which defines __powikf2 as __powikf2_hw.  The
  37    __powikf2_hw.c is compiled with -mcpu=power9 and it automatically uses the
  38    IEEE 128-bit instructions.
  39
  40    For #2/#3, float128-ifunc.c defines an ifunc function for __powikf2, that
  41    will use the software version on power7/power8 systems, and the hardware
  42    version on power9 systems.
  43
  44    The code is cloned from the code in libgcc2.c (which handles the standard
  45    SF, DF, TF, and XF types).  */
  46
  47 #if defined(FLOAT128_HW_INSNS) && !defined(__powikf2)
  48 #define __powikf2 __powikf2_sw
  49 #endif
  50
  51 TFtype
  52 __powikf2 (TFtype x, SItype_ppc m)
  53 {
  54   unsigned int n = m < 0 ? -m : m;
  55   TFtype y = n % 2 ? x : 1;
  56   while (n >>= 1)
  57     {
  58       x = x * x;
  59       if (n % 2)
  60         y = y * x;
  61     }
  62   return m < 0 ? 1/y : y;
  63 }