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dnl Additional copyrights may follow
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dnl


AC_DEFUN([PRTE_CHECK_GCC_ATOMIC_BUILTINS], [
  if test -z "$prte_cv_have___atomic" ; then
    AC_MSG_CHECKING([for 32-bit GCC built-in atomics])
    AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <stdint.h>
]],[[
uint32_t tmp, old = 0;
uint64_t tmp64, old64 = 0;
__atomic_thread_fence(__ATOMIC_SEQ_CST);
__atomic_compare_exchange_n(&tmp, &old, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED);
__atomic_add_fetch(&tmp, 1, __ATOMIC_RELAXED);
__atomic_compare_exchange_n(&tmp64, &old64, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED);
__atomic_add_fetch(&tmp64, 1, __ATOMIC_RELAXED);]])],
        [prte_cv_have___atomic=yes],
        [prte_cv_have___atomic=no])
    AC_MSG_RESULT([$prte_cv_have___atomic])

    if test "$prte_cv_have___atomic" = "yes" ; then
      AC_MSG_CHECKING([for 64-bit GCC built-in atomics])
      AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <stdint.h>
]],[[
uint64_t tmp64, old64 = 0;
__atomic_compare_exchange_n(&tmp64, &old64, 1, 0, __ATOMIC_RELAXED, __ATOMIC_RELAXED);
__atomic_add_fetch(&tmp64, 1, __ATOMIC_RELAXED);]])],
            [prte_cv_have___atomic_64=yes],
            [prte_cv_have___atomic_64=no])
      AC_MSG_RESULT([$prte_cv_have___atomic_64])
      if test "$prte_cv_have___atomic_64" = "yes" ; then
        AC_MSG_CHECKING([if 64-bit GCC built-in atomics are lock-free])
        AC_RUN_IFELSE([AC_LANG_PROGRAM([], [if (!__atomic_is_lock_free (8, 0)) { return 1; }])],
              [AC_MSG_RESULT([yes])],
              [AC_MSG_RESULT([no])
               prte_cv_have___atomic_64=no],
              [AC_MSG_RESULT([cannot test -- assume yes (cross compiling)])])
      fi
    else
      prte_cv_have___atomic_64=no
    fi
  fi
])

dnl #################################################################
dnl
dnl PRTE_CONFIG_ASM()
dnl
dnl DEFINE PRTE_ATOMIC_C11 if C11 atomics should be used
dnl DEFINE PRTE_ATOMIC_GCC_BUILTIN if gcc builtin atomics should be used
dnl DEFINE PRTE_ATOMIC_X86_64 if we're on an x86_64 platform
dnl
dnl #################################################################
AC_DEFUN([PRTE_CONFIG_ASM],[
    AC_REQUIRE([PRTE_SETUP_CC])

    AC_ARG_ENABLE([c11-atomics],[AS_HELP_STRING([--enable-c11-atomics],
                  [Enable use of C11 atomics if available (default: enabled)])])
    AC_ARG_ENABLE([builtin-atomics],
      [AS_HELP_STRING([--enable-builtin-atomics],
         [Enable use of GCC built-in atomics (default: autodetect)])])

    prte_atomic_c11=0
    prte_atomic_gcc_builtin=0

    PRTE_CHECK_GCC_ATOMIC_BUILTINS
    if test "x$enable_c11_atomics" != "xno" && test "$prte_cv_c11_supported" = "yes" ; then
        prte_atomic_style="c11"
        prte_atomic_c11=1
    elif test "x$enable_c11_atomics" = "xyes"; then
        AC_MSG_WARN([C11 atomics were requested but are not supported])
        AC_MSG_ERROR([Cannot continue])
    elif test "$enable_builtin_atomics" != "no" && test "$prte_cv_have___atomic" = "yes" ; then
        prte_atomic_style="gcc"
        prte_atomic_gcc_builtin=1
    elif test "$enable_builtin_atomics" = "yes" ; then
        AC_MSG_WARN([GCC built-in atomics requested but not found.])
        AC_MSG_ERROR([Cannot continue])
    else
        AC_MSG_WARN([Neither C11 nor the built-in atomics are available,])
        AC_MSG_WARN([either because they were disabled on the configure])
        AC_MSG_WARN([command line or they were not found. PRRTE requires])
        AC_MSG_WARN([atomic support, so either a compiler with C11 atomics])
        AC_MSG_WARN([must be used OR the built-in atomics must not be disabled.])
        AC_MSG_ERROR([Cannot continue])
    fi

    AC_MSG_CHECKING([for x86_64 architecture])
    case "${host}" in
    x86_64-*x32|i?86-*|x86_64*|amd64*)
        AC_MSG_RESULT([yes])
        AC_DEFINE([PRTE_ATOMIC_X86_64], [1], [whether building on x86_64 platform])
        ;;
    *)
        AC_MSG_RESULT([no])
        ;;
    esac

    AC_MSG_CHECKING([for atomics style])
    AC_MSG_RESULT([$prte_atomic_style])

    AC_DEFINE_UNQUOTED([PRTE_ATOMIC_C11], [$prte_atomic_c11],
        [Use C11 style atomics])

    AC_DEFINE_UNQUOTED([PRTE_ATOMIC_GCC_BUILTIN], [$prte_atomic_gcc_builtin],
        [Use GCC builtin style atomics])
])dnl