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Try to use __builtin_ffsl if ffsl is unavailable.

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Some platforms (like those using Newlib) don't have ffs/ffsl.  This
commit adds a check to configure.ac for __builtin_ffsl if ffsl isn't
found.  __builtin_ffsl performs the same function as ffsl, and has the
added benefit of being available on any platform utilizing
Gcc-compatible compiler.

This change does not address the used of ffs in the MALLOCX_ARENA()
macro.
This commit is contained in:
Richard Diamond
2014-05-28 21:37:02 -05:00
committed by Jason Evans
parent 0b5c92213f
commit 9c3a10fdf6
9 changed files with 71 additions and 17 deletions
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30
configure.ac
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@@ -1109,9 +1109,11 @@ elif test "x${force_tls}" = "x1" ; then
fi
dnl ============================================================================
dnl Check for ffsl(3), and fail if not found. This function exists on all
dnl platforms that jemalloc currently has a chance of functioning on without
dnl modification.
dnl Check for ffsl(3), then __builtin_ffsl(), and fail if neither are found.
dnl One of those two functions should (theoretically) exist on all platforms
dnl that jemalloc currently has a chance of functioning on without modification.
dnl We additionally assume ffs() or __builtin_ffs() are defined if
dnl ffsl() or __builtin_ffsl() are defined, respectively.
JE_COMPILABLE([a program using ffsl], [
#include <stdio.h>
#include <strings.h>
@@ -1122,8 +1124,26 @@ JE_COMPILABLE([a program using ffsl], [
printf("%d\n", rv);
}
], [je_cv_function_ffsl])
if test "x${je_cv_function_ffsl}" != "xyes" ; then
AC_MSG_ERROR([Cannot build without ffsl(3)])
if test "x${je_cv_function_ffsl}" == "xyes" ; then
AC_DEFINE([JEMALLOC_INTERNAL_FFSL], [ffsl])
AC_DEFINE([JEMALLOC_INTERNAL_FFS], [ffs])
else
JE_COMPILABLE([a program using __builtin_ffsl], [
#include <stdio.h>
#include <strings.h>
#include <string.h>
], [
{
int rv = __builtin_ffsl(0x08);
printf("%d\n", rv);
}
], [je_cv_gcc_builtin_ffsl])
if test "x${je_cv_gcc_builtin_ffsl}" == "xyes" ; then
AC_DEFINE([JEMALLOC_INTERNAL_FFSL], [__builtin_ffsl])
AC_DEFINE([JEMALLOC_INTERNAL_FFS], [__builtin_ffs])
else
AC_MSG_ERROR([Cannot build without ffsl(3) or __builtin_ffsl()])
fi
fi
dnl ============================================================================