ceph/src/erasure-code/jerasure/jerasure/m4/ax_gcc_x86_cpuid.m4

   1 # ===========================================================================
   2 #     http://www.gnu.org/software/autoconf-archive/ax_gcc_x86_cpuid.html
   3 # ===========================================================================
   4 #
   5 # SYNOPSIS
   6 #
   7 #   AX_GCC_X86_CPUID(OP)
   8 #
   9 # DESCRIPTION
  10 #
  11 #   On Pentium and later x86 processors, with gcc or a compiler that has a
  12 #   compatible syntax for inline assembly instructions, run a small program
  13 #   that executes the cpuid instruction with input OP. This can be used to
  14 #   detect the CPU type.
  15 #
  16 #   On output, the values of the eax, ebx, ecx, and edx registers are stored
  17 #   as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
  18 #   ax_cv_gcc_x86_cpuid_OP.
  19 #
  20 #   If the cpuid instruction fails (because you are running a
  21 #   cross-compiler, or because you are not using gcc, or because you are on
  22 #   a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
  23 #   is set to the string "unknown".
  24 #
  25 #   This macro mainly exists to be used in AX_GCC_ARCHFLAG.
  26 #
  27 # LICENSE
  28 #
  29 #   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
  30 #   Copyright (c) 2008 Matteo Frigo
  31 #
  32 #   This program is free software: you can redistribute it and/or modify it
  33 #   under the terms of the GNU General Public License as published by the
  34 #   Free Software Foundation, either version 3 of the License, or (at your
  35 #   option) any later version.
  36 #
  37 #   This program is distributed in the hope that it will be useful, but
  38 #   WITHOUT ANY WARRANTY; without even the implied warranty of
  39 #   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
  40 #   Public License for more details.
  41 #
  42 #   You should have received a copy of the GNU General Public License along
  43 #   with this program. If not, see <http://www.gnu.org/licenses/>.
  44 #
  45 #   As a special exception, the respective Autoconf Macro's copyright owner
  46 #   gives unlimited permission to copy, distribute and modify the configure
  47 #   scripts that are the output of Autoconf when processing the Macro. You
  48 #   need not follow the terms of the GNU General Public License when using
  49 #   or distributing such scripts, even though portions of the text of the
  50 #   Macro appear in them. The GNU General Public License (GPL) does govern
  51 #   all other use of the material that constitutes the Autoconf Macro.
  52 #
  53 #   This special exception to the GPL applies to versions of the Autoconf
  54 #   Macro released by the Autoconf Archive. When you make and distribute a
  55 #   modified version of the Autoconf Macro, you may extend this special
  56 #   exception to the GPL to apply to your modified version as well.
  57
  58 #serial 7
  59
  60 AC_DEFUN([AX_GCC_X86_CPUID],
  61 [AC_REQUIRE([AC_PROG_CC])
  62 AC_LANG_PUSH([C])
  63 AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
  64  [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
  65      int op = $1, eax, ebx, ecx, edx;
  66      FILE *f;
  67       __asm__("cpuid"
  68         : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
  69         : "a" (op));
  70      f = fopen("conftest_cpuid", "w"); if (!f) return 1;
  71      fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
  72      fclose(f);
  73      return 0;
  74 ])],
  75      [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
  76      [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
  77      [ax_cv_gcc_x86_cpuid_$1=unknown])])
  78 AC_LANG_POP([C])
  79 ])